1
|
Geng Z, Wang J, Cao G, Tan C, Li L, Qiu J. Differential impact of heat and hypoxia on dynamic oxygen uptake and deoxyhemoglobin parameters during incremental exhaustive exercise. Front Physiol 2024; 14:1247659. [PMID: 38260100 PMCID: PMC10801013 DOI: 10.3389/fphys.2023.1247659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 12/13/2023] [Indexed: 01/24/2024] Open
Abstract
Purpose: This study aims to explore the relationship between the dynamic changes in oxygen uptake (V ˙ O 2 ) and deoxyhemoglobin (HHb) and peripheral fatigue in athletes during incremental exhaustive exercise under different environmental conditions, including high temperature and humidity environment, hypoxic environment, and normal conditions. Methods: 12 male modern pentathlon athletes were recruited and performed incremental exhaustive exercise in three different environments: normal condition (23°C, 45%RH, FiO2 = 21.0%, CON), high temperature and humidity environment (35°C, 70%RH, FiO2 = 21.0%, HOT), and hypoxic environment (23°C, 45%RH, FiO2 = 15.6%, HYP). Gas metabolism data of the athletes were collected, and muscle oxygen saturation (SmO2) and total hemoglobin content in the vastus lateralis muscles (VL) were measured to calculate the deoxyhemoglobin content. Linear and nonlinear function models were used to fit the characteristic parameters of V ˙ O 2 and HHb changes. Results: The results showed that compared to the CON, V ˙ O 2 , V ˙ CO 2 , and exercise time were decreased in the HOT and HYP (p < 0.05). Δ E V ˙ O 2 and OUES were reduced in the HOT and HYP compared to the CON (p < 0.05). The Gas exchange threshold in the CON corresponded to higher V ˙ O 2 than in the HYP and HOT (p < 0.05). Δ E V ˙ O 2 - 1 was reduced in the HOT compared to the HYP (p < 0.05). ΔEHHb was higher in the HOT compared to the CON (p < 0.05). ΔEHHb-1 was increased in the HYP compared to the CON (p < 0.05). There was a negative correlation between ΔEHHb and corresponding V ˙ O 2 max in the HOT (r = -0.655, p < 0.05), and a negative correlation between ΔEHHb-1 and corresponding V ˙ O 2 max in the HYP (r = -0.606, p < 0.05). Conclusion: Incremental exhaustive exercise in hypoxic environment and high temperature and humidity environments inhibits gas exchange and oxygen supply to skeletal muscle tissue in athletes. For athletes, the accelerated deoxygenation response of skeletal muscles during incremental exhaustive exercise in high temperature and humidity environments, as well as the excessive deoxygenation response before BP of deoxyhemoglobin in hypoxic environment, may be contributing factors to peripheral fatigue under different environmental conditions.
Collapse
Affiliation(s)
- Zhizhong Geng
- School of Sports and Health, Shanghai University of Sport, Shanghai, China
| | - Jinhao Wang
- Shanghai Research Institute of Sports Science, Shanghai, China
| | - Guohuan Cao
- Shanghai Research Institute of Sports Science, Shanghai, China
| | - Chenhao Tan
- Shanghai Research Institute of Sports Science, Shanghai, China
| | - Longji Li
- School of Sports and Health, Shanghai University of Sport, Shanghai, China
| | - Jun Qiu
- Shanghai Research Institute of Sports Science, Shanghai, China
| |
Collapse
|
2
|
BALDASSARRE GIOVANNI, AZZINI VALERIA, ZUCCARELLI LUCREZIA, DEGANO CRISTINA, GRANIERO FRANCESCO, PLETT GLORIA, FLOREANI MIRCO, LAZZER STEFANO, MOS LUCIO, GRASSI BRUNO. In Cardiac Patients β-Blockers Attenuate the Decrease in Work Rate during Exercise at a Constant Submaximal Heart Rate. Med Sci Sports Exerc 2023; 55:1995-2001. [PMID: 37257085 PMCID: PMC10581439 DOI: 10.1249/mss.0000000000003230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
PURPOSE Exercise prescription based on fixed heart rate (HR) values is not associated with a specific work rate (WR) during prolonged exercise. This phenomenon has never been evaluated in cardiac patients and might be associated with a slow component of HR kinetics and β-adrenergic activity. The aims were to quantify, in cardiac patients, the WR decrease at a fixed HR and to test if it would be attenuated by β-blockers. METHODS Seventeen patients with coronary artery disease in stable conditions (69 ± 9 yr) were divided into two groups according to the presence (BB) or absence (no-BB) of a therapy with β-blockers, and performed on a cycle ergometer: an incremental exercise (INCR) and a 15-min "HR CLAMPED " exercise, in which WR was continuously adjusted to maintain a constant HR, corresponding to the gas exchange threshold +15%. HR was determined by the ECG signal, and pulmonary gas exchange was assessed breath-by-breath. RESULTS During INCR, HR peak was lower in BB versus no-BB ( P < 0.05), whereas no differences were observed for other variables. During HR CLAMPED , the decrease in WR needed to maintain HR constant was less pronounced in BB versus no-BB (-16% ± 10% vs -27 ± 10, P = 0.04) and was accompanied by a decreased V̇O 2 only in no-BB (-13% ± 6%, P < 0.001). CONCLUSIONS The decrease in WR during a 15-min exercise at a fixed HR (slightly higher than that at gas exchange threshold) was attenuated in BB, suggesting a potential role by β-adrenergic stimulation. The phenomenon may represent, also in this population, a sign of impaired exercise tolerance and interferes with aerobic exercise prescription.
Collapse
Affiliation(s)
| | - VALERIA AZZINI
- Department of Medicine, University of Udine, Udine, ITALY
- Department of Cardiology, San Daniele del Friuli Hospital, San Daniele del Friuli, ITALY
| | | | | | - FRANCESCO GRANIERO
- Physical Exercise Prescription Center, Gemona del Friuli Hospital, Gemona del Friuli, ITALY
| | - GLORIA PLETT
- Department of Medicine, University of Udine, Udine, ITALY
| | - MIRCO FLOREANI
- Department of Medicine, University of Udine, Udine, ITALY
- Physical Exercise Prescription Center, Gemona del Friuli Hospital, Gemona del Friuli, ITALY
- School of Sport Sciences, University of Udine, Udine, ITALY
| | - STEFANO LAZZER
- Department of Medicine, University of Udine, Udine, ITALY
- Physical Exercise Prescription Center, Gemona del Friuli Hospital, Gemona del Friuli, ITALY
- School of Sport Sciences, University of Udine, Udine, ITALY
| | - LUCIO MOS
- Department of Cardiology, San Daniele del Friuli Hospital, San Daniele del Friuli, ITALY
| | - BRUNO GRASSI
- Department of Medicine, University of Udine, Udine, ITALY
| |
Collapse
|
3
|
Love LK, Hodgson MD, Keir DA, Kowalchuk JM. The effect of increasing work rate amplitudes from a common metabolic baseline on the kinetic response of V̇o 2p, blood flow, and muscle deoxygenation. J Appl Physiol (1985) 2023; 135:584-600. [PMID: 37439241 DOI: 10.1152/japplphysiol.00566.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 06/29/2023] [Accepted: 07/06/2023] [Indexed: 07/14/2023] Open
Abstract
A step-transition in external work rate (WR) increases pulmonary O2 uptake (V̇o2p) in a monoexponential fashion. Although the rate of this increase, quantified by the time constant (τ), has frequently been shown to be similar between multiple different WR amplitudes (ΔWR), the adjustment of O2 delivery to the muscle (via blood flow; BF), a potential regulator of V̇o2p kinetics, has not been extensively studied. To investigate the role of BF on V̇o2p kinetics, 10 participants performed step-transitions on a knee-extension ergometer from a common baseline WR (3 W) to: 24, 33, 45, 54, and 66 W. Each transition lasted 8 min and was repeated four to six times. Volume turbinometry and mass spectrometry, Doppler ultrasound, and near-infrared spectroscopy were used to measure V̇o2p, BF, and muscle deoxygenation (deoxy[Hb + Mb]), respectively. Similar transitions were ensemble-averaged, and phase II V̇o2p, BF, and deoxy[Hb + Mb] were fit with a monoexponential nonlinear least squares regression equation. With increasing ΔWR, τV̇o2p became larger at the higher ΔWRs (P < 0.05), while τBF did not change significantly, and the mean response time (MRT) of deoxy[Hb + Mb] became smaller. These findings that V̇o2p kinetics become slower with increasing ΔWR, while BF kinetics are not influenced by ΔWR, suggest that O2 delivery could not limit V̇o2p in this situation. However, the speeding of deoxy[Hb + Mb] kinetics with increasing ΔWR does imply that the O2 delivery-to-O2 utilization of the microvasculature decreases at higher ΔWRs. This suggests that the contribution of O2 delivery and O2 extraction to V̇O2 in the muscle changes with increasing ΔWR.NEW & NOTEWORTHY A step increase in work rate produces a monoexponential increase in V̇o2p and blood flow to a new steady-state. We found that step transitions from a common metabolic baseline to increasing work rate amplitudes produced a slowing of V̇o2p kinetics, no change in blood flow kinetics, and a speeding of muscle deoxygenation kinetics. As work rate amplitude increased, the ratio of blood flow to V̇o2p became smaller, while the amplitude of muscle deoxygenation became greater. The gain in vascular conductance became smaller, while kinetics tended to become slower at higher work rate amplitudes.
Collapse
Affiliation(s)
- Lorenzo K Love
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario, Canada
- Department of Kinesiology and Physical Education, Redeemer University, Ancaster, Ontario, Canada
| | - Michael D Hodgson
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario, Canada
| | - Daniel A Keir
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario, Canada
- Toronto General Research Institute, Toronto General Hospital, Toronto, Ontario, Canada
| | - John M Kowalchuk
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Ontario, Canada
- Department of Kinesiology and Physical Education, Redeemer University, Ancaster, Ontario, Canada
| |
Collapse
|
4
|
Korzeniewski B. Sensitivity of V̇O2max, critical power and V̇O2 on-kinetics to O2 concentration/delivery and other factors in skeletal muscle. Respir Physiol Neurobiol 2023; 307:103977. [DOI: 10.1016/j.resp.2022.103977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/29/2022] [Accepted: 10/03/2022] [Indexed: 11/07/2022]
|
5
|
KATO T, MUROGA S, YAMASHIRO SM, MATSUMOTO T. Effect of 3% CO2 inhalation on pulmonary gas exchange kinetics during constant work-rate exercise. GAZZETTA MEDICA ITALIANA ARCHIVIO PER LE SCIENZE MEDICHE 2022. [DOI: 10.23736/s0393-3660.20.04529-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
6
|
Baldassarre G, Zuccarelli L, Manferdelli G, Manfredini V, Marzorati M, Pilotto A, Porcelli S, Rasica L, Šimunič B, Pišot R, Narici M, Grassi B. Decrease in work rate in order to keep a constant heart rate: biomarker of exercise intolerance following a 10-day bed rest. J Appl Physiol (1985) 2022; 132:1569-1579. [PMID: 35511721 DOI: 10.1152/japplphysiol.00052.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Aerobic exercise prescription is often set at specific heart rate (HR) values. Previous studies demonstrated that during exercise carried out at a HR slightly above that corresponding to the gas exchange threshold (GET), work rate (WR) has to decrease in order to maintain HR constant. We hypothesized a greater WR decrease at a fixed HR following simulated microgravity/inactivity (bed rest, BR). Ten male volunteers (23±5 yr) were tested before (PRE) and after (POST) a 10-day horizontal BR, and performed on a cycle ergometer: a) incremental exercise; b) 15-min HRCLAMPED exercise, in which WR was continuously adjusted to maintain a constant HR, corresponding to that at 120% of GET determined in PRE; c) two moderate-intensity constant WR (MOD) exercises. Breath-by-breath VO2, HR and other variables were determined. After BR, VO2peak and GET significantly decreased, by about 10%. During HRCLAMPED (145±11 b∙min-1), the decrease in WR needed to maintain a constant HR was greater in POST vs. PRE (-39±10 vs. -29±14%, p<0.01). In 6 subjects the decreased WR switched from the heavy- to the moderate-intensity domain. The decrease in WR during HRCLAMPED, in PRE vs. POST, was significantly correlated with the VO2peak decrease (R2=0.52; p=0.02). A greater amplitude of the slow component of the HR kinetics was observed during MOD following BR. Exercise at a fixed HR is not associated with a specific WR or WR domain; the problem, affecting exercise evaluation and prescription, is greater following BR. The WR decrease during HRCLAMPED is a biomarker of exercise intolerance following BR.
Collapse
Affiliation(s)
| | | | - Giorgio Manferdelli
- Institute of Biomedical Technologies, National Research Council, Segrate, Italy
| | | | - Mauro Marzorati
- Institute of Biomedical Technologies, National Research Council, Segrate, Italy
| | - Andrea Pilotto
- Department of Medicine, University of Udine, Udine, Italy.,Institute of Biomedical Technologies, National Research Council, Segrate, Italy
| | - Simone Porcelli
- Institute of Biomedical Technologies, National Research Council, Segrate, Italy.,Department of Molecular Medicine, University of Pavia, Italy
| | - Letizia Rasica
- Institute of Biomedical Technologies, National Research Council, Segrate, Italy
| | - Boštjan Šimunič
- Institute for Kinesiology Research, Science and Research Center, Koper, Slovenia
| | - Rado Pišot
- Institute for Kinesiology Research, Science and Research Center, Koper, Slovenia
| | - Marco Narici
- Department of Biomedical Sciences, University of Padova, Italy
| | - Bruno Grassi
- Department of Medicine, University of Udine, Udine, Italy
| |
Collapse
|
7
|
A century of exercise physiology: key concepts on coupling respiratory oxygen flow to muscle energy demand during exercise. Eur J Appl Physiol 2022; 122:1317-1365. [PMID: 35217911 PMCID: PMC9132876 DOI: 10.1007/s00421-022-04901-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 01/25/2022] [Indexed: 12/26/2022]
Abstract
After a short historical account, and a discussion of Hill and Meyerhof’s theory of the energetics of muscular exercise, we analyse steady-state rest and exercise as the condition wherein coupling of respiration to metabolism is most perfect. The quantitative relationships show that the homeostatic equilibrium, centred around arterial pH of 7.4 and arterial carbon dioxide partial pressure of 40 mmHg, is attained when the ratio of alveolar ventilation to carbon dioxide flow (\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$${\dot{V}}_{A}/{\dot{V}}_{R}{CO}_{2}$$\end{document}V˙A/V˙RCO2) is − 21.6. Several combinations, exploited during exercise, of pertinent respiratory variables are compatible with this equilibrium, allowing adjustment of oxygen flow to oxygen demand without its alteration. During exercise transients, the balance is broken, but the coupling of respiration to metabolism is preserved when, as during moderate exercise, the respiratory system responds faster than the metabolic pathways. At higher exercise intensities, early blood lactate accumulation suggests that the coupling of respiration to metabolism is transiently broken, to be re-established when, at steady state, blood lactate stabilizes at higher levels than resting. In the severe exercise domain, coupling cannot be re-established, so that anaerobic lactic metabolism also contributes to sustain energy demand, lactate concentration goes up and arterial pH falls continuously. The \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$${\dot{V}}_{A}/{\dot{V}}_{R}{CO}_{2}$$\end{document}V˙A/V˙RCO2 decreases below − 21.6, because of ensuing hyperventilation, while lactate keeps being accumulated, so that exercise is rapidly interrupted. The most extreme rupture of the homeostatic equilibrium occurs during breath-holding, because oxygen flow from ambient air to mitochondria is interrupted. No coupling at all is possible between respiration and metabolism in this case.
Collapse
|
8
|
Zuccarelli L, Sartorio A, DE Micheli R, Tringali G, Grassi B. Obese Patients Decrease Work Rate in Order to Keep a Constant Target Heart Rate. Med Sci Sports Exerc 2021; 53:986-993. [PMID: 33148969 DOI: 10.1249/mss.0000000000002551] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE "Slow components" of heart rate (HR) kinetics, occurring also during moderate-intensity constant work rate exercise, represent a problem for exercise prescription at fixed HR values. This problem, described in young healthy subjects, could be more pronounced in obese patients. METHODS Sixteen male obese patients (age, 22 ± 7 yr; body mass, 127 ± 19 kg; body mass index, 41.6 ± 3.9 kg·m-2) were tested before (PRE) and after (POST) a 3-wk multidisciplinary body mass reduction program, entailing moderate-intensity exercise. They performed on a cycle ergometer an incremental exercise to voluntary exhaustion (to determine peak pulmonary oxygen uptake (V˙O2peak) and gas exchange threshold (GET)) and constant work rate exercises: moderate-intensity (MODERATE; 80% of GET determined in PRE), heavy-intensity (HEAVY; 120% of GET determined in PRE), and "HRCLAMPED" exercise, in which work rate was continuously adjusted to maintain a constant HR corresponding to that at 120% of GET. Breath-by-breath V˙O2 and HR were determined. RESULTS V˙O2peak and GET (expressed as a percent of V˙O2peak) were not significantly different in PRE versus POST. In POST versus PRE, the HR slow component disappeared (MODERATE) or was reduced (HEAVY). In PRE, work rate had to decrease by ~20% over a 15-min task in order to keep HR constant; this decrease was significantly smaller (~5%) in POST. CONCLUSIONS In obese patients, a 3-wk multidisciplinary body mass reduction intervention i) increased exercise tolerance by eliminating (during MODERATE) or by reducing (during HEAVY) the slow component of HR kinetics, and ii) facilitated exercise prescription by allowing to translate a fixed submaximal HR value into a work rate slightly above GET.
Collapse
Affiliation(s)
| | | | - Roberta DE Micheli
- Experimental Laboratory for Auxo-endocrinological Research, Istituto Auxologico Italiano, IRCCS, Milan and Piancavallo (VB), ITALY
| | - Gabriella Tringali
- Experimental Laboratory for Auxo-endocrinological Research, Istituto Auxologico Italiano, IRCCS, Milan and Piancavallo (VB), ITALY
| | - Bruno Grassi
- Department of Medicine, University of Udine, Udine, ITALY
| |
Collapse
|
9
|
Reduction of Oxygen Saturation and Increase of Heart Rate in Hospital Workers Wearing Face Mask during Routine Shift. JOURNAL OF RESEARCH IN APPLIED AND BASIC MEDICAL SCIENCES 2021. [DOI: 10.52547/rabms.7.1.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
|
10
|
Sousa AC, Millet GP, Viana J, Milheiro J, Reis V. Effects of Normobaric Hypoxia on Matched-severe Exercise and Power-duration Relationship. Int J Sports Med 2021; 42:708-715. [PMID: 33461230 DOI: 10.1055/a-1236-3953] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We investigated the effects of hypoxia on matched-severe intensity exercise and on the parameters of the power-duration relationship. Fifteen trained subjects performed in both normoxia and normobaric hypoxia (FiO2=0.13, ~3000 m) a maximal incremental test, a 3 min all-out test (3AOT) and a transition from rest to an exercise performed to exhaustion (Tlim) at the same relative intensity (80%∆). Respiratory and pulmonary gas-exchange variables were continuously measured (K5, Cosmed, Italy). Tlim test's V̇O2 kinetics was calculated using a two-component exponential model. V̇O2max (44.1±5.1 vs. 58.7±6.4 ml.kg-1.min-1, p<0.001) was decreased in hypoxia. In Tlim, time-to-exhaustion sustained was similar (454±130 vs. 484±169 s) despite that V̇O2 kinetics was slower (τ1: 31.1±5.8 vs. 21.6±4.7 s, p<0.001) and the amplitude of the V̇O2 slow component lower (12.4±5.4 vs. 20.2±5.7 ml.kg-1.min-1, p<0.05) in hypoxia. CP was reduced (225±35 vs. 270±49 W, p<0.001) but W' was unchanged (11.3±2.9 vs. 11.4±2.7 kJ) in hypoxia. The changes in CP/V̇O2max were positively correlated with changes in W' (r = 0.58, p<0.05). The lower oxygen availability had an impact on aerobic related physiological parameters, but exercise tolerance is similar between hypoxia and normoxia when the relative intensity is matched despite a slower V̇O2 kinetics in hypoxia.
Collapse
Affiliation(s)
- Ana Catarina Sousa
- Research Center in Sports Sciences, Health Sciences and Human Development, CIDESD, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal.,University Institute of Maia, ISMAI, Maia, Portugal
| | - Gregoire P Millet
- ISSUL, University of Lausanne, Institute of Sport Sciences and Physical Education (ISSEP), Lausanne, Switzerland
| | - João Viana
- Research Center in Sports Sciences, Health Sciences and Human Development, CIDESD, University Institute of Maia, ISMAI, Maia, Portugal
| | | | - Vítor Reis
- CMEP - Exercise Medical Center, Porto, Portugal
| |
Collapse
|
11
|
Hedge ET, Hughson RL. Frequency domain analysis to extract dynamic response characteristics for oxygen uptake during transitions to moderate- and heavy-intensity exercises. J Appl Physiol (1985) 2020; 129:1422-1430. [PMID: 33054659 DOI: 10.1152/japplphysiol.00503.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
At the onset of an exercise transition, exponential modeling to calculate a time constant (τ) is the conventional method to analyze pulmonary oxygen uptake (V̇O2p) kinetics for moderate and heavy exercises. A new frequency domain analysis technique, mean normalized gain (MNG), has been used to analyze V̇O2p kinetics during moderate exercise, but has not been evaluated for its ability to detect differences in kinetics between moderate and heavy exercises. This study tested the hypothesis that MNG would detect smaller amplitude V̇O2p responses in the heavy-exercise domain compared with moderate-exercise domain. Eight young healthy adults (3 female; age: 27 ± 6 yr; peak V̇O2p: 43 ± 6 mL·min-1·kg-1; means ± SD) performed three bouts of pseudorandom binary sequence (PRBS) exercise for frequency analysis, with the work rate (WR) changing between 25 W and 90% ventilatory threshold (VT; L → MPRBS), 25 W and 50% of the difference between VT and peak V̇O2p (Δ50%; L → HPRBS), and VT to Δ50% (VT → HPRBS). Step exercise tests with equivalent changes in WR to the PRBS tests were performed to facilitate the comparison between MNG and τ. MNG was the highest for L → MPRBS (59 ± 7%), then L → HPRBS (52 ± 6%), and the lowest for VT → HPRBS (38 ± 7%, F(2,14) = 129.755, P < 0.001) exercise conditions indicating slower kinetics with increasing exercise intensity that correlated strongly in repeated measures with τ from step transitions (rrm = -0.893). These results indicate that frequency domain analysis and MNG reliably detect differences in V̇O2p kinetics observed across exercise intensity domains.NEW & NOTEWORTHY Mean normalized gain is able to detect differences in V̇O2p kinetics between moderate-, heavy-, and heavy-intensity exercises from a raised WR within the same individuals. This new method of kinetic analysis may be advantageous compared with conventional V̇O2p curve fitting, as it is less sensitive to breath-by-breath noise, it can provide useful information from a single exercise testing session, and it can be applied to nonconstant work rate exercise situations.
Collapse
Affiliation(s)
- Eric T Hedge
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada.,Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Richard L Hughson
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada.,Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| |
Collapse
|
12
|
Loeppky JA, Salgado RM, Sheard AC, Kuethe DO, Mermier CM. Variations in exercise ventilation in hypoxia will affect oxygen uptake. Physiol Int 2020; 107:431-443. [PMID: 33021952 DOI: 10.1556/2060.2020.00031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 07/03/2020] [Indexed: 11/19/2022]
Abstract
Reports of VO2 response differences between normoxia and hypoxia during incremental exercise do not agree. In this study VO2 and VE were obtained from 15-s averages at identical work rates during continuous incremental cycle exercise in 8 subjects under ambient pressure (633 mmHg ≈1,600 m) and during duplicate tests in acute hypobaric hypoxia (455 mmHg ≈4,350 m), ranging from 49 to 100% of VO2 peak in hypoxia and 42-87% of VO2 peak in normoxia. The average VO2 was 96 mL/min (619 mL) lower at 455 mmHg (n.s. P = 0.15) during ramp exercises. Individual response points were better described by polynomial than linear equations (mL/min/W). The VE was greater in hypoxia, with marked individual variation in the differences which correlated significantly and directly with the VO2 difference between 455 mmHg and 633 mmHg (P = 0.002), likely related to work of breathing (Wb). The greater VE at 455 mmHg resulted from a greater breathing frequency. When a subject's hypoxic ventilatory response is high, the extra work of breathing reduces mechanical efficiency (E). Mean ∆E calculated from individual linear slopes was 27.7 and 30.3% at 633 and 455 mmHg, respectively (n.s.). Gross efficiency (GE) calculated from mean VO2 and work rate and correcting for Wb from a VE-VO2 relationship reported previously, gave corresponding values of 20.6 and 21.8 (P = 0.05). Individual variation in VE among individuals overshadows average trends, as also apparent from other reports comparing hypoxia and normoxia during progressive exercise and must be considered in such studies.
Collapse
Affiliation(s)
- J A Loeppky
- 1Department of Health, Exercise and Sports Sciences, University of New Mexico, Albuquerque, NM 87131, Canada.,2Research Section, VA Medical Center, Albuquerque, NM 87108, Canada
| | - R M Salgado
- 3United States Army Research, Institute of Environmental Medicine, Thermal and Mountain Medicine Division, Natick, MA 01760, USA
| | - A C Sheard
- 4School of Kinesiology and Nutritional Science, California State University, Los Angeles, CA 90032, USA
| | - D O Kuethe
- 5New Mexico Resonance, Albuquerque, NM 87106, Canada
| | - C M Mermier
- 6Department of Health, Exercise and Sports Sciences, University of New Mexico, Albuquerque, NM 87131, Canada
| |
Collapse
|
13
|
Zuccarelli L, do Nascimento Salvador PC, Del Torto A, Fiorentino R, Grassi B. Skeletal muscle V̇o2 kinetics by the NIRS repeated occlusions method during the recovery from cycle ergometer exercise. J Appl Physiol (1985) 2020; 128:534-544. [DOI: 10.1152/japplphysiol.00580.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Near-infrared spectroscopy (NIRS) has been utilized as a noninvasive method to evaluate skeletal muscle mitochondrial function in humans, by calculating muscle V̇o2 (V̇o2 m) recovery (off-) kinetics following short light-intensity plantar flexion exercise. The aim of the present study was to determine V̇o2 m off- kinetics following standard cycle ergometer exercise of different intensities. Fifteen young physically active healthy men performed an incremental exercise (INCR) up to exhaustion and two repetitions of constant work-rate (CWR) exercises at 80% of gas exchange threshold (GET; MODERATE) and at 40% of the difference between GET and peak pulmonary V̇o2 (V̇o2 p; HEAVY). V̇o2 p and vastus lateralis muscle fractional O2 extraction by NIRS (Δ[deoxy(Hb+Mb)]) were recorded continuously. Transient arterial occlusions were carried out at rest and during the recovery for V̇o2 m calculation. All subjects tolerated the repeated occlusions protocol without problems. The quality of the monoexponential fitting for V̇o2 m off-kinetics analysis was excellent (0.93≤ r2≤0.99). According to interclass correlation coefficient, the test-retest reliability was moderate to good. V̇o2 m values at the onset of recovery were ~27, ~38, and ~35 times higher (in MODERATE, HEAVY, and INCR, respectively) than at rest. The time constants (τ) of V̇o2 m off-kinetics were lower ( P < 0.001) following MODERATE (29.1 ± 6.8 s) vs. HEAVY (40.8 ± 10.9) or INCR (42.9 ± 10.9), suggesting an exercise intensity dependency of V̇o2 m off-kinetics. Only following MODERATE the V̇o2 m off-kinetics were faster than the V̇o2 p off-kinetics. V̇o2 m off-kinetics, determined noninvasively by the NIRS repeated occlusions technique, can be utilized as a functional evaluation tool of skeletal muscle oxidative metabolism also following conventional cycle ergometer exercise. NEW & NOTEWORTHY This is the first study in which muscle V̇o2 recovery kinetics, determined noninvasively by near-infrared spectroscopy (NIRS) by utilizing the repeated occlusions method, was applied following standard cycle ergometer exercise of different intensities. The results demonstrate that muscle V̇o2 recovery kinetics, determined noninvasively by the NIRS repeated occlusions technique, can be utilized as a functional evaluation tool of skeletal muscle oxidative metabolism also following conventional cycle ergometer exercise, overcoming significant limitations associated with the traditionally proposed protocol.
Collapse
Affiliation(s)
| | | | | | | | - Bruno Grassi
- Department of Medicine, University of Udine, Udine, Italy
| |
Collapse
|
14
|
Hirai DM, Craig JC, Colburn TD, Eshima H, Kano Y, Musch TI, Poole DC. Skeletal muscle interstitial Po 2 kinetics during recovery from contractions. J Appl Physiol (1985) 2019; 127:930-939. [PMID: 31369325 DOI: 10.1152/japplphysiol.00297.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The oxygen partial pressure in the interstitial space (Po2 is) drives O2 into the myocyte via diffusion, thus supporting oxidative phosphorylation. Although crucial for metabolic recovery and the capacity to perform repetitive tasks, the time course of skeletal muscle Po2 is during recovery from contractions remains unknown. We tested the hypothesis that Po2 is would recover to resting values and display considerable on-off asymmetry (fast on-, slow off-kinetics), reflective of asymmetric capillary hemodynamics. Microvascular Po2 (Po2 mv) was also evaluated to test the hypothesis that a significant transcapillary gradient (ΔPo2 = Po2 mv - Po2 is) would be sustained during recovery. Po2 mv and Po2 is (expressed in mmHg) were determined via phosphorescence quenching in the exposed rat spinotrapezius muscle during and after submaximal twitch contractions (n = 12). Po2 is rose exponentially (P < 0.05) from end-contraction (11.1 ± 5.1), such that the end-recovery value (17.9 ± 7.9) was not different from resting Po2 is (18.5 ± 8.1; P > 0.05). Po2 is off-kinetics were slower than on-kinetics (mean response time: 53.1 ± 38.3 versus 18.5 ± 7.3 s; P < 0.05). A significant transcapillary ΔPo2 observed at end-contraction (16.6 ± 7.4) was maintained throughout recovery (end-recovery: 18.8 ± 9.6; P > 0.05). Consistent with our hypotheses, muscle Po2 is recovered to resting values with slower off-kinetics compared with the on-transient in line with the on-off asymmetry for capillary hemodynamics. Maintenance of a substantial transcapillary ΔPo2 during recovery supports that the microvascular-interstitium interface provides considerable resistance to O2 transport. As dictated by Fick's law (V̇o2 = Do2 × ΔPo2), modulation of O2 flux (V̇o2) during recovery must be achieved via corresponding changes in effective diffusing capacity (Do2; mainly capillary red blood cell hemodynamics and distribution) in the face of unaltered ΔPo2.NEW & NOTEWORTHY Capillary blood-myocyte O2 flux (V̇o2) is determined by effective diffusing capacity (Do2; mainly erythrocyte hemodynamics and distribution) and microvascular-interstitial Po2 gradients (ΔPo2 = Po2 mv - Po2 is). We show that Po2 is demonstrates on-off asymmetry consistent with Po2 mv and erythrocyte kinetics during metabolic transitions. A substantial transcapillary ΔPo2 was preserved during recovery from contractions, indicative of considerable resistance to O2 diffusion at the microvascular-interstitium interface. This reveals that effective Do2 declines in step with V̇o2 during recovery, as per Fick's law.
Collapse
Affiliation(s)
- Daniel M Hirai
- Department of Health and Kinesiology, Purdue University, West Lafayette, Indiana.,Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Jesse C Craig
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas.,Department of Internal Medicine, University of Utah, Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Hiroaki Eshima
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Yutaka Kano
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| |
Collapse
|
15
|
Lunghi A, Brocherie F, Millet GP. Influence of Altitude on Elite Biathlon Performances. High Alt Med Biol 2019; 20:312-317. [PMID: 31199701 DOI: 10.1089/ham.2019.0008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Biathlon is a complex sport subjected to large performance variability. Among the environmental conditions (e.g., temperature, wind, snow conditions) susceptible to influence performance, altitude is likely a detrimental factor for skiing (i.e., due to decreased aerobic capacity) as well as for prone and/or-to a larger extent-standing shooting (i.e., due to altered postural control and increased ventilation) performances. The aim of the present study was therefore to analyze the influence of altitude on elite biathlon performance. The analysis comprised data extracted from the International Biathlon Union (IBU) website and included IBU World Cup, IBU Cup, IBU World Championships, and Olympic Winter Games events over 8 years from season 2009-2010 to 2016-2017. The research included sprint, individual, mass start, and pursuit competitions for both men and women (no relays). The event sites were divided into three different altitude ranges: <700, 700-1400, and >1400 m. Only the Top-30 of each race were recorded for both men and women, separately, and analyzed for skiing speed, prone, and standing shooting performances. The results show a detrimental effect of altitude (i.e., ∼3.0% between <700 and >1400 m) on shooting performance that was similar for men and women but without any statistical difference between prone and standing positions. Due to many other confounding factors not analyzed here (snow quality, course profile), the effect of altitude on skiing speed was unclear. Overall, as expected, elite biathlon performances are altered, even within the range of moderate altitudes of the IBU competitions (<1800 m).
Collapse
Affiliation(s)
- Alex Lunghi
- ISSUL, Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Franck Brocherie
- Laboratory Sport, Expertise and Performance (EA7370), Research Department, French Institute of Sport, Paris, France
| | - Grégoire P Millet
- ISSUL, Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| |
Collapse
|
16
|
Abstract
Pulmonary oxygen uptake ( V˙O2 ) kinetics, which describes the aerobic response to near instantaneous changes in metabolic demand, provides a valuable insight into the control and coordination of oxidative phosphorylation during exercise. Despite their applicability to the highly sporadic habitual physical activity and exercise patterns of children, relatively little is known regarding the influence of internal and external stimuli on the dynamic V˙O2 response. Although insufficient evidence is available during moderate-intensity exercise, an age-related slowing of the phase 2 time constant (τ) and augmentation of the V˙O2 slow component appears to manifest during heavy-intensity exercise, which may be related to changes in the muscle phosphate controllers of oxidative phosphorylation, muscle oxygen delivery and utilization, and/or muscle fiber type recruitment patterns. Similar to findings in adults, aerobic training is associated with a faster phase 2 τ and smaller V˙O2 slow component in youth, independent of age or maturity, indicative of an enhanced oxidative metabolism. However, a lack of longitudinal or intervention-based training studies limits our ability to attribute these changes to training per se. Further, methodologically rigorous studies are required to fully resolve the interaction(s) between age, sex, biological maturity, and external stimuli, such as exercise training and exercise intensity and the dynamic V˙O2 response at the onset and offset of exercise.
Collapse
|
17
|
SHARMA AVISHP, SAUNDERS PHILOU, GARVICAN-LEWIS LAURAA, CLARK BRAD, GORE CHRISTOPHERJ, THOMPSON KEVING, PÉRIARD JULIEND. Normobaric Hypoxia Reduces V˙O2 at Different Intensities in Highly Trained Runners. Med Sci Sports Exerc 2019; 51:174-182. [DOI: 10.1249/mss.0000000000001745] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
18
|
Physiological resolution of periodic breath holding during heavy-intensity Fartlek exercise. Eur J Appl Physiol 2018; 118:2627-2639. [DOI: 10.1007/s00421-018-3986-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 09/02/2018] [Indexed: 11/25/2022]
|
19
|
ZUCCARELLI LUCREZIA, PORCELLI SIMONE, RASICA LETIZIA, MARZORATI MAURO, GRASSI BRUNO. Comparison between Slow Components of HR and V˙O2 Kinetics: Functional Significance. Med Sci Sports Exerc 2018; 50:1649-1657. [DOI: 10.1249/mss.0000000000001612] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
20
|
Ebine N, Aoki T, Itoh M, Fukuoka Y. Differential kinetics of the cardiac, ventilatory, and gas exchange variables during walking under moderate hypoxia. PLoS One 2018; 13:e0200186. [PMID: 30044809 PMCID: PMC6059434 DOI: 10.1371/journal.pone.0200186] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 06/21/2018] [Indexed: 11/19/2022] Open
Abstract
We investigated the effects of moderate hypoxia (FiO2 = 15%) on different kinetics between pulmonary ventilation ( V˙E) and heart rate (HR) during treadmill walking. Breath-by-breath V˙E, oxygen uptake ( V˙O2), carbon dioxide output ( V˙CO2), and HR were measured in 13 healthy young adults. The treadmill speed was sinusoidally changed from 3 to 6 km·h-1 with four oscillation periods of 1, 2, 5, and 10 min. The amplitude (Amp), phase shift (PS) and mean values of these kinetics were obtained by harmonic analysis. The mean values of all of these responses during walking at a sinusoidally changing speed became greater under hypoxia compared to normoxia (FiO2 = 21%), indicating that moderate hypoxia could achieve an increased energy expenditure (increased V˙O2 and V˙CO2) and hyperventilation. The Amp values of the V˙E, V˙O2, and V˙CO2 kinetics were not significantly different between normoxia and hypoxia at most periods, although a significantly smaller Amp of the HR was observed at faster oscillation periods (1 or 2 min).The PS of the HR was significantly greater under hypoxia than normoxia at the 2, 5, and 10 min periods, whereas the PS of the V˙E, V˙O2, and V˙CO2 responses was not significantly different between normoxia and hypoxia at any period. These findings suggest that the lesser changes in Amp and PS in ventilatory and gas exchange kinetics during walking at a sinusoidally changing speed were remarkably different from a deceleration in HR kinetics under moderate hypoxia.
Collapse
Affiliation(s)
- Naoyuki Ebine
- Faculty of Health and Sports Sciences, Doshisha University, Tatara, Kyotanabe, Kyoto, Japan
| | - Tomoko Aoki
- Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Higashiku, Kumamoto, Japan
| | - Masahiro Itoh
- Department of Physiology, Kumamoto University Graduate School of Life Sciences, Chyoku, Kumamoto, Japan
| | - Yoshiyuki Fukuoka
- Faculty of Health and Sports Sciences, Doshisha University, Tatara, Kyotanabe, Kyoto, Japan
- Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Higashiku, Kumamoto, Japan
- * E-mail:
| |
Collapse
|
21
|
Koga S, Okushima D, Barstow TJ, Rossiter HB, Kondo N, Poole DC. Near-infrared spectroscopy of superficial and deep rectus femoris reveals markedly different exercise response to superficial vastus lateralis. Physiol Rep 2018; 5:5/17/e13402. [PMID: 28912130 PMCID: PMC5599862 DOI: 10.14814/phy2.13402] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 08/08/2017] [Accepted: 08/08/2017] [Indexed: 12/13/2022] Open
Abstract
To date our knowledge of skeletal muscle deoxygenation as measured by near-infrared spectroscopy (NIRS) is predicated almost exclusively on sampling of superficial muscle(s), most commonly the vastus lateralis (VL-s). Recently developed high power NIRS facilitates simultaneous sampling of deep (i.e., rectus femoris, RF-d) and superficial muscles of RF (RF-s) and VL-s. Because deeper muscle is more oxidative with greater capillarity and sustains higher blood flows than superficial muscle, we used time-resolved NIRS to test the hypotheses that, following exercise onset, the RF-d has slower deoxy[Hb+Mb] kinetics with reduced amplitude than superficial muscles. Thirteen participants performed cycle exercise transitions from unloaded to heavy work rates. Within the same muscle (RF-s vs. RF-d) deoxy[Hb+Mb] kinetics (mean response time, MRT) and amplitudes were not different. However, compared with the kinetics of VL-s, deoxy[Hb+Mb] of RF-s and RF-d were slower (MRT: RF-s, 51 ± 23; RF-d, 55 ± 29; VL-s, 18 ± 6 s; P < 0.05). Moreover, the amplitude of total[Hb+Mb] was greater for VL-s than both RF-s and RF-d (P < 0.05). Whereas pulmonary V˙O2 kinetics (i.e., on vs. off) were symmetrical in heavy exercise, there was a marked on-off asymmetry of deoxy[Hb+Mb] for all three sites i.e., MRT-off > MRT-on (P < 0.05). Collectively these data reveal profoundly different O2 transport strategies, with the RF-s and RF-d relying proportionately more on elevated perfusive and the VL-s on diffusive O2 transport. These disparate O2 transport strategies and their temporal profiles across muscles have previously been concealed within the "global" pulmonary V˙O2 response.
Collapse
Affiliation(s)
- Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Dai Okushima
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Thomas J Barstow
- Departments of Anatomy and Physiology, and Kinesiology, Kansas State University, Manhattan, Kansas
| | - Harry B Rossiter
- Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California.,Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Narihiko Kondo
- Applied Physiology Laboratory, Kobe University, Kobe, Japan
| | - David C Poole
- Departments of Anatomy and Physiology, and Kinesiology, Kansas State University, Manhattan, Kansas
| |
Collapse
|
22
|
Physiological Responses to Treadmill Running With Body Weight Support in Hypoxia Compared With Normoxia. J Sport Rehabil 2018; 27:224-229. [PMID: 28338405 DOI: 10.1123/jsr.2016-0210] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
CONTEXT Anecdotal reports suggest elite sports clubs combine lower-body positive-pressure rehabilitation with a hypoxic stimulus to maintain or increase physiological and metabolic strain, which are reduced during lower-body positive pressure. However, the effects of hypoxia on cardiovascular and metabolic response during lower-body positive-pressure rehabilitation are unknown. OBJECTIVE Evaluate the use of normobaric hypoxia as a means to increase physiological strain during body-weight-supported (BWS) running. DESIGN Crossover study. SETTING Controlled laboratory. PARTICIPANTS Seven familiarized males (mean (SD): age, 20 (1) y; height, 1.77 (0.05) m; mass, 69.4 (5.1) kg; hemoglobin, 15.2 (0.8) g·dL-1) completed a normoxic and hypoxic (fraction of inspired oxygen [O2] = 0.14) trial, during which they ran at 8 km·h-1 on an AlterG™ treadmill with 0%, 30%, and 60% BWS in a randomized order for 10 minutes interspersed with 5 minutes of recovery. MAIN OUTCOME MEASURES Arterial O2 saturation, heart rate, O2 delivery, and measurements of metabolic strain via indirect calorimetry. RESULTS Hypoxic exercise reduced hemoglobin O2 saturation and elevated heart rate at each level of BWS compared with normoxia. However, the reduction in hemoglobin O2 saturation was attenuated at 60% BWS compared with 0% and 30%, and consequently, O2 delivery was better maintained at 60% BWS. CONCLUSION Hypoxia is a practically useful means of increasing physiological strain during BWS rehabilitation. In light of the maintenance of hemoglobin O2 saturation and O2 delivery at increasing levels of BWS, fixed hemoglobin saturations rather than a fixed altitude are recommended to maintain an aerobic stimulus.
Collapse
|
23
|
Conceição MS, Gáspari AF, Ramkrapes APB, Junior EMM, Bertuzzi R, Cavaglieri CR, Chacon-Mikahil MPT. Anaerobic metabolism induces greater total energy expenditure during exercise with blood flow restriction. PLoS One 2018; 13:e0194776. [PMID: 29596452 PMCID: PMC5875813 DOI: 10.1371/journal.pone.0194776] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 03/11/2018] [Indexed: 11/18/2022] Open
Abstract
PURPOSE We investigated the energy system contributions and total energy expenditure during low intensity endurance exercise associated with blood flow restriction (LIE-BFR) and without blood flow restriction (LIE). METHODS Twelve males participated in a contra-balanced, cross-over design in which subjects completed a bout of low-intensity endurance exercise (30min cycling at 40% of [Formula: see text]) with or without BFR, separated by at least 72 hours of recovery. Blood lactate accumulation and oxygen uptake during and after exercise were used to estimate the anaerobic lactic metabolism, aerobic metabolism, and anaerobic alactic metabolism contributions, respectively. RESULTS There were significant increases in the anaerobic lactic metabolism (P = 0.008), aerobic metabolism (P = 0.020), and total energy expenditure (P = 0.008) in the LIE-BFR. No significant differences between conditions for the anaerobic alactic metabolism were found (P = 0.582). Plasma lactate concentration was significantly higher in the LIE-BFR at 15min and peak post-exercise (all P≤0.008). Heart rate was significantly higher in the LIE-BFR at 10, 15, 20, 25, and 30min during exercise, and 5, 10, and 15min after exercise (all P≤0.03). Ventilation was significantly higher in the LIE-BFR at 10, 15, and 20min during exercise (all P≤0.003). CONCLUSION Low-intensity endurance exercise performed with blood flow restriction increases the anaerobic lactic and aerobic metabolisms, total energy expenditure, and cardiorespiratory responses.
Collapse
Affiliation(s)
- Miguel S. Conceição
- Exercise Physiology Lab., School of Physical Education, University of Campinas–Campinas/Brazil
- School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
| | - Arthur F. Gáspari
- Exercise Physiology Lab., School of Physical Education, University of Campinas–Campinas/Brazil
- Endurance Sports Research Group (GEDAE-USP), School of Physical Education and Sport, University of São Paulo—São Paulo/Brazil
| | - Ana P. B. Ramkrapes
- Exercise Physiology Lab., School of Physical Education, University of Campinas–Campinas/Brazil
| | - Edson M. M. Junior
- Exercise Physiology Lab., School of Physical Education, University of Campinas–Campinas/Brazil
| | - Romulo Bertuzzi
- School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
- Endurance Sports Research Group (GEDAE-USP), School of Physical Education and Sport, University of São Paulo—São Paulo/Brazil
| | - Cláudia R. Cavaglieri
- Exercise Physiology Lab., School of Physical Education, University of Campinas–Campinas/Brazil
| | | |
Collapse
|
24
|
Mankowski RT, Niemeijer VM, Jansen JP, Spraakman L, Stam HJ, Praet SFE. Oxygen delivery is not a limiting factor during post-exercise recovery in healthy young adults. J Exerc Sci Fit 2018. [PMID: 29541131 PMCID: PMC5812842 DOI: 10.1016/j.jesf.2017.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Purpose It is still equivocal whether oxygen uptake recovery kinetics are limited by oxygen delivery and can be improved by supplementary oxygen. The present study aimed to investigate whether measurements of muscle and pulmonary oxygen uptake kinetics can be used to assess oxygen delivery limitations in healthy subjects. Methods Sixteen healthy young adults performed three sub-maximal exercise tests (6 min at 40% Wmax) under hypoxic (14%O2), normoxic (21%O2) and hyperoxic (35%O2) conditions on separate days in randomized order. Both Pulmonary VO2 and near infra red spectroscopy (NIRS) based Tissue Saturation Index (TSI) offset kinetics were calculated using mono-exponential curve fitting models. Results Time constant τ of VO2 offset kinetics under hypoxic (44.9 ± 7.3s) conditions were significantly larger than τ of the offset kinetics under normoxia (37.9 ± 8.2s, p = 0.02) and hyperoxia (37±6s, p = 0.04). TSI mean response time (MRT) of the offset kinetics under hypoxic conditions (25.5 ± 13s) was significantly slower than under normoxic (15 ± 7.7, p = 0.007) and hyperoxic (13 ± 7.3, p = 0.008) conditions. Conclusion The present study shows that there was no improvement in the oxygen uptake and muscle oxygenation recovery kinetics in healthy subjects under hyperoxic conditions. Slower TSI and VO2 recovery kinetics under hypoxic conditions indicate that both NIRS and spiro-ergometry are appropriate non-invasive measurement tools to assess the physiological response of a healthy individual to hypoxic exercise.
Collapse
Affiliation(s)
- Robert T Mankowski
- Subdivision MOVEFIT-Sports Medicine, Dept. of Rehabilitation Medicine, Erasmus University Medical Center, Wytemaweg 80, 3000 CA Rotterdam, The Netherlands.,Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA
| | - Victor M Niemeijer
- Department of Cardiology, Máxima Medical Centre, P.O. Box 7777, 5500 MB, Veldhoven, The Netherlands
| | - Jasper P Jansen
- Department of Cardiology, Máxima Medical Centre, P.O. Box 7777, 5500 MB, Veldhoven, The Netherlands.,Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Lotte Spraakman
- Subdivision MOVEFIT-Sports Medicine, Dept. of Rehabilitation Medicine, Erasmus University Medical Center, Wytemaweg 80, 3000 CA Rotterdam, The Netherlands
| | - Henk J Stam
- Subdivision MOVEFIT-Sports Medicine, Dept. of Rehabilitation Medicine, Erasmus University Medical Center, Wytemaweg 80, 3000 CA Rotterdam, The Netherlands
| | - Stephan F E Praet
- Subdivision MOVEFIT-Sports Medicine, Dept. of Rehabilitation Medicine, Erasmus University Medical Center, Wytemaweg 80, 3000 CA Rotterdam, The Netherlands.,Department of Sports Medicine, Australian Institute of Sport, Canberra, Australia
| |
Collapse
|
25
|
Slow V˙O 2 kinetics in acute hypoxia are not related to a hyperventilation-induced hypocapnia. Respir Physiol Neurobiol 2018; 251:41-49. [PMID: 29477729 DOI: 10.1016/j.resp.2018.02.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 02/01/2018] [Accepted: 02/16/2018] [Indexed: 11/21/2022]
Abstract
We examined whether slower pulmonary O2 uptake (V˙O2p) kinetics in hypoxia is a consequence of: a) hypoxia alone (lowered arterial O2 pressure), b) hyperventilation-induced hypocapnia (lowered arterial CO2 pressure), or c) a combination of both. Eleven participants performed 3-5 repetitions of step-changes in cycle ergometer power output from 20W to 80% lactate threshold in the following conditions: i) normoxia (CON; room air); ii) hypoxia (HX, inspired O2 = 12%; lowered end-tidal O2 pressure [PETO2] and end-tidal CO2 pressure [PETCO2]); iii) hyperventilation (HV; increased PETO2 and lowered PETCO2); and iv) normocapnic hypoxia (NC-HX; lowered PETO2 and PETCO2 matched to CON). Ventilation was increased (relative to CON) and matched between HX, HV, and NC-HX conditions. During each condition VO2p˙ was measured and phase II V˙O2p kinetics were modeled with a mono-exponential function. The V˙O2p time constant was different (p < 0.05) amongst all conditions: CON, 26 ± 11s; HV, 36 ± 14s; HX, 46 ± 14s; and NC-HX, 52 ± 13s. Hypocapnia may prevent further slowing of V˙O2p kinetics in hypoxic exercise.
Collapse
|
26
|
Black MI, Potter CR, Corbett J, Clark CCT, Draper SB. Maximal Oxygen Uptake Is Achieved in Hypoxia but Not Normoxia during an Exhaustive Severe Intensity Run. Front Physiol 2017; 8:96. [PMID: 28270770 PMCID: PMC5319197 DOI: 10.3389/fphys.2017.00096] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 02/06/2017] [Indexed: 01/01/2023] Open
Abstract
Highly aerobically trained individuals are unable to achieve maximal oxygen uptake (V˙O2max) during exhaustive running lasting ~2 min, instead V˙O2 plateaus below V˙O2max after ~1 min. Hypoxia offers the opportunity to study the (V˙O2) response to an exhaustive run relative to a hypoxia induced reduction in V˙O2max. The aim of this study was to explore whether there is a difference in the percentage of V˙O2max achieved (during a 2 min exhaustive run) in normoxia and hypoxia. Fourteen competitive middle distance runners (normoxic V˙O2max 67.0 ± 5.2 ml.kg−1.min−1) completed exhaustive treadmill ramp tests and constant work rate (CWR) tests in normoxia and hypoxia (FiO2 0.13). The V˙O2 data from the CWR tests were modeled using a single exponential function. End exercise normoxic CWR V˙O2 was less than normoxic V˙O2max (86 ± 6% ramp, P < 0.001). During the hypoxic CWR test, hypoxic V˙O2max was achieved (102 ± 8% ramp, P = 0.490). The phase II time constant was greater in hypoxia (12.7 ± 2.8 s) relative to normoxia (10.4 ± 2.6 s) (P = 0.029). The results demonstrate that highly aerobically trained individuals cannot achieve V˙O2max during exhaustive severe intensity treadmill running in normoxia, but can achieve the lower V˙O2max in hypoxia despite a slightly slower V˙O2 response.
Collapse
Affiliation(s)
- Matthew I Black
- School of Sport, Exercise and Health Sciences, Loughborough University Loughborough, UK
| | | | - Jo Corbett
- Department of Sport and Exercise Science, University of Portsmouth Portsmouth, UK
| | - Cain C T Clark
- HE Sport, University Centre, Hartpury College Gloucestershire, UK
| | - Stephen B Draper
- HE Sport, University Centre, Hartpury College Gloucestershire, UK
| |
Collapse
|
27
|
Niemeijer VM, Spee RF, Schoots T, Wijn PFF, Kemps HMC. Limitations of skeletal muscle oxygen delivery and utilization during moderate-intensity exercise in moderately impaired patients with chronic heart failure. Am J Physiol Heart Circ Physiol 2016; 311:H1530-H1539. [DOI: 10.1152/ajpheart.00474.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 09/28/2016] [Indexed: 11/22/2022]
Abstract
The extent and speed of transient skeletal muscle deoxygenation during exercise onset in patients with chronic heart failure (CHF) are related to impairments of local O2 delivery and utilization. This study examined the physiological background of submaximal exercise performance in 19 moderately impaired patients with CHF (Weber class A, B, and C) compared with 19 matched healthy control (HC) subjects by measuring skeletal muscle oxygenation (SmO2) changes during cycling exercise. All subjects performed two subsequent moderate-intensity 6-min exercise tests (bouts 1 and 2) with measurements of pulmonary oxygen uptake kinetics and SmO2 using near-infrared spatially resolved spectroscopy at the vastus lateralis for determination of absolute oxygenation values, amplitudes, kinetics (mean response time for onset), and deoxygenation overshoot characteristics. In CHF, deoxygenation kinetics were slower compared with HC (21.3 ± 5.3 s vs. 16.7 ± 4.4 s, P < 0.05, respectively). After priming exercise (i.e., during bout 2), deoxygenation kinetics were accelerated in CHF to values no longer different from HC (16.9 ± 4.6 s vs. 15.4 ± 4.2 s, P = 0.35). However, priming did not speed deoxygenation kinetics in CHF subjects with a deoxygenation overshoot, whereas it did reduce the incidence of the overshoot in this specific group ( P < 0.05). These results provide evidence for heterogeneity with respect to limitations of O2 delivery and utilization during moderate-intensity exercise in patients with CHF, with slowed deoxygenation kinetics indicating a predominant O2 utilization impairment and the presence of a deoxygenation overshoot, with a reduction after priming in a subgroup, indicating an initial O2 delivery to utilization mismatch.
Collapse
Affiliation(s)
- Victor M. Niemeijer
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven, the Netherlands; and
| | - Ruud F. Spee
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
| | - Thijs Schoots
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
| | - Pieter F. F. Wijn
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven, the Netherlands; and
- Department of Medical Physics, Máxima Medical Centre, Veldhoven, the Netherlands
| | - Hareld M. C. Kemps
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
| |
Collapse
|
28
|
Horiuchi M, Handa Y, Abe D, Fukuoka Y. Walking economy at simulated high altitude in human healthy young male lowlanders. Biol Open 2016; 5:1408-1414. [PMID: 27744292 PMCID: PMC5087691 DOI: 10.1242/bio.019810] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
We measured oxygen consumption during walking per unit distance (Cw) values for 12 human healthy young males at six speeds from 0.667 to 1.639 m s−1 (four min per stage) on a level gradient under normobaric normoxia, moderate hypoxia (15% O2), and severe hypoxia (11% O2). Muscle deoxygenation (HHb) was measured at the vastus lateralis muscle using near-infrared spectroscopy. Economical speed which can minimize the Cw in each individual was calculated from a U-shaped relationship. We found a significantly slower economical speed (ES) under severe hypoxia [1.237 (0.056) m s−1; mean (s.d.)] compared to normoxia [1.334 (0.070) m s−1] and moderate hypoxia [1.314 (0.070) m s−1, P<0.05 respectively] with no differences between normoxia and moderate hypoxia (P>0.05). HHb gradually increased with increasing speed under severe hypoxia, while it did not increase under normoxia and moderate hypoxia. Changes in HHb between standing baseline and the final minute at faster gait speeds were significantly related to individual ES (r=0.393 at 1.250 m s−1, r=0.376 at 1.444 m s−1, and r=0.409 at 1.639 m s−1, P<0.05, respectively). These results suggested that acute severe hypoxia slowed ES by ∼8%, but moderate hypoxia left ES unchanged. Summary: Acute severe hypoxia slowed the economical speed (ES) which can minimize energy cost of walking. Muscle O2 extraction may be one of the determining factors of an individual's ES.
Collapse
Affiliation(s)
- Masahiro Horiuchi
- Division of Human Environmental Science, Mt. Fuji Research Institute, Kami-yoshida 5597-1, Fuji-yoshida-city, Yamanashi 4030005, Japan
| | - Yoko Handa
- Division of Human Environmental Science, Mt. Fuji Research Institute, Kami-yoshida 5597-1, Fuji-yoshida-city, Yamanashi 4030005, Japan
| | - Daijiro Abe
- Center for Health and Sports Science, Kyushu Sangyo University, Matsukadai 2-3-1, Higashi-ku, Fukuoka-city, Fukuoka 8138503, Japan
| | - Yoshiyuki Fukuoka
- Faculty of Health and Sports Science, Doshisha University, Tatara 1-3, Kyotanabe, Kyoto 6100394, Japan
| |
Collapse
|
29
|
Álvarez-Herms J, Julià-Sánchez S, Corbi F, Pagès T, Viscor G. A program of circuit resistance training under hypobaric hypoxia conditions improves the anaerobic performance of athletes. Sci Sports 2016. [DOI: 10.1016/j.scispo.2015.08.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
30
|
Ciccone AB, Brown LE, Coburn JW, Galpin AJ. Effects of traditional vs. alternating whole-body strength training on squat performance. J Strength Cond Res 2015; 28:2569-77. [PMID: 24942175 DOI: 10.1519/jsc.0000000000000586] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Traditional strength training with 80% of 1 repetition maximum (1RM) uses 2- to 5-minute rest periods between sets. These long rest periods minimize decreases in volume and intensity but result in long workouts. Performing upper-body exercises during lower-body rest intervals may decrease workout duration but may affect workout performance. Therefore, the purpose of this study was to compare the effects of traditional vs. alternating whole-body strength training on squat performance. Twenty male (24 ± 2 years) volunteers performed 2 workouts. The traditional set (TS) workout consisted of 4 sets of squats (SQ) at 80% of 1RM on a force plate with 3-minute rest between sets. The alternating set (AS) workout also consisted of 4 sets of SQ at 80% of 1RM but with bench press, and bench pull exercises performed between squat sets 1, 2 and 3 with between-exercise rest of 50 seconds, resulting in approximately 3-minute rest between squat sets. Sets 1-3 were performed for 4 repetitions, whereas set 4 was performed to concentric failure. Total number of completed repetitions of the fourth squat set to failure was recorded. Peak ground reaction force (GRF), peak power (PP), and average power (AP) of every squat repetition were recorded and averaged for each set. There was no significant interaction for GRF, PP, or AP. However, volume-equated AP was greater during the TS condition (989 ± 183) than the AS condition (937 ± 176). During the fourth squat set, the TS condition resulted in more repetitions to failure (7.5 ± 2.2) than the AS condition (6.5 ± 2.2). Therefore, individuals who aim to optimize squat AP should refrain from performing more than 3 ASs per exercise. Likewise, those who aim to maximize squat repetitions to failure should refrain from performing upper-body multijoint exercises during squat rest intervals.
Collapse
Affiliation(s)
- Anthony B Ciccone
- Center for Sport Performance, Department of Kinesiology, California State University, Fullerton, California
| | | | | | | |
Collapse
|
31
|
Liu G, Liu X, Qin Z, Gu Z, Wang G, Shi W, Wen D, Yu L, Luo Y, Xiao H. Cardiovascular System Response to Carbon Dioxide and Exercise in Oxygen-Enriched Environment at 3800 m. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2015; 12:11781-96. [PMID: 26393634 PMCID: PMC4586707 DOI: 10.3390/ijerph120911781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 08/05/2015] [Accepted: 08/06/2015] [Indexed: 11/22/2022]
Abstract
Background: This study explores the responses of the cardiovascular system as humans exercise in an oxygen-enriched room at high altitude under various concentrations of CO2. Methods: The study utilized a hypobaric chamber set to the following specifications: 3800 m altitude with 25% O2 and different CO2 concentrations of 0.5% (C1), 3.0% (C2) and 5.0% (C3). Subjects exercised for 3 min three times, separated by 30 min resting periods in the above-mentioned conditions, at sea level (SL) and at 3800 m altitude (HA). The changes of heart rate variability, heart rate and blood pressure were analyzed. Results: Total power (TP) and high frequency power (HF) decreased notably during post-exercise at HA. HF increased prominently earlier the post-exercise period at 3800 m altitude with 25% O2 and 5.0% CO2 (C3), while low frequency power (LF) changed barely in all tests. The ratios of LF/HF were significantly higher during post-exercise in HA, and lower after high intensity exercise in C3. Heart rate and systolic blood pressure increased significantly in HA and C3. Conclusions: Parasympathetic activity dominated in cardiac autonomic modulation, and heart rate and blood pressure increased significantly after high intensity exercise in C3.
Collapse
Affiliation(s)
- Guohui Liu
- School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China.
| | - Xiaopeng Liu
- High Altitude Physiology Laboratory, Institute of Aviation Medicine, Air Force, Beijing 100142, China.
| | - Zhifeng Qin
- High Altitude Physiology Laboratory, Institute of Aviation Medicine, Air Force, Beijing 100142, China.
| | - Zhao Gu
- High Altitude Physiology Laboratory, Institute of Aviation Medicine, Air Force, Beijing 100142, China.
| | - Guiyou Wang
- High Altitude Physiology Laboratory, Institute of Aviation Medicine, Air Force, Beijing 100142, China.
| | - Weiru Shi
- High Altitude Physiology Laboratory, Institute of Aviation Medicine, Air Force, Beijing 100142, China.
| | - Dongqing Wen
- High Altitude Physiology Laboratory, Institute of Aviation Medicine, Air Force, Beijing 100142, China.
| | - Lihua Yu
- High Altitude Physiology Laboratory, Institute of Aviation Medicine, Air Force, Beijing 100142, China.
| | - Yongchang Luo
- High Altitude Physiology Laboratory, Institute of Aviation Medicine, Air Force, Beijing 100142, China.
| | - Huajun Xiao
- High Altitude Physiology Laboratory, Institute of Aviation Medicine, Air Force, Beijing 100142, China.
| |
Collapse
|
32
|
Chong JW, Dao DK, Salehizadeh SMA, McManus DD, Darling CE, Chon KH, Mendelson Y. Photoplethysmograph signal reconstruction based on a novel hybrid motion artifact detection-reduction approach. Part I: Motion and noise artifact detection. Ann Biomed Eng 2014; 42:2238-50. [PMID: 25092422 DOI: 10.1007/s10439-014-1080-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 07/25/2014] [Indexed: 11/30/2022]
Abstract
Motion and noise artifacts (MNA) are a serious obstacle in utilizing photoplethysmogram (PPG) signals for real-time monitoring of vital signs. We present a MNA detection method which can provide a clean vs. corrupted decision on each successive PPG segment. For motion artifact detection, we compute four time-domain parameters: (1) standard deviation of peak-to-peak intervals (2) standard deviation of peak-to-peak amplitudes (3) standard deviation of systolic and diastolic interval ratios, and (4) mean standard deviation of pulse shape. We have adopted a support vector machine (SVM) which takes these parameters from clean and corrupted PPG signals and builds a decision boundary to classify them. We apply several distinct features of the PPG data to enhance classification performance. The algorithm we developed was verified on PPG data segments recorded by simulation, laboratory-controlled and walking/stair-climbing experiments, respectively, and we compared several well-established MNA detection methods to our proposed algorithm. All compared detection algorithms were evaluated in terms of motion artifact detection accuracy, heart rate (HR) error, and oxygen saturation (SpO2) error. For laboratory controlled finger, forehead recorded PPG data and daily-activity movement data, our proposed algorithm gives 94.4, 93.4, and 93.7% accuracies, respectively. Significant reductions in HR and SpO2 errors (2.3 bpm and 2.7%) were noted when the artifacts that were identified by SVM-MNA were removed from the original signal than without (17.3 bpm and 5.4%). The accuracy and error values of our proposed method were significantly higher and lower, respectively, than all other detection methods. Another advantage of our method is its ability to provide highly accurate onset and offset detection times of MNAs. This capability is important for an automated approach to signal reconstruction of only those data points that need to be reconstructed, which is the subject of the companion paper to this article. Finally, our MNA detection algorithm is real-time realizable as the computational speed on the 7-s PPG data segment was found to be only 7 ms with a Matlab code.
Collapse
Affiliation(s)
- Jo Woon Chong
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA, 01609-2280, USA,
| | | | | | | | | | | | | |
Collapse
|
33
|
Abstract
Muscular exercise requires transitions to and from metabolic rates often exceeding an order of magnitude above resting and places prodigious demands on the oxidative machinery and O2-transport pathway. The science of kinetics seeks to characterize the dynamic profiles of the respiratory, cardiovascular, and muscular systems and their integration to resolve the essential control mechanisms of muscle energetics and oxidative function: a goal not feasible using the steady-state response. Essential features of the O2 uptake (VO2) kinetics response are highly conserved across the animal kingdom. For a given metabolic demand, fast VO2 kinetics mandates a smaller O2 deficit, less substrate-level phosphorylation and high exercise tolerance. By the same token, slow VO2 kinetics incurs a high O2 deficit, presents a greater challenge to homeostasis and presages poor exercise tolerance. Compelling evidence supports that, in healthy individuals walking, running, or cycling upright, VO2 kinetics control resides within the exercising muscle(s) and is therefore not dependent upon, or limited by, upstream O2-transport systems. However, disease, aging, and other imposed constraints may redistribute VO2 kinetics control more proximally within the O2-transport system. Greater understanding of VO2 kinetics control and, in particular, its relation to the plasticity of the O2-transport/utilization system is considered important for improving the human condition, not just in athletic populations, but crucially for patients suffering from pathologically slowed VO2 kinetics as well as the burgeoning elderly population.
Collapse
Affiliation(s)
- David C Poole
- Departments of Kinesiology, Anatomy, and Physiology, Kansas State University, Manhattan, Kansas, USA.
| | | |
Collapse
|
34
|
Bowen TS, Rossiter HB, Benson AP, Amano T, Kondo N, Kowalchuk JM, Koga S. Slowed oxygen uptake kinetics in hypoxia correlate with the transient peak and reduced spatial distribution of absolute skeletal muscle deoxygenation. Exp Physiol 2013; 98:1585-96. [DOI: 10.1113/expphysiol.2013.073270] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
35
|
Christensen PM, Nyberg M, Mortensen SP, Nielsen JJ, Secher NH, Damsgaard R, Hellsten Y, Bangsbo J. Leg oxygen uptake in the initial phase of intense exercise is slowed by a marked reduction in oxygen delivery. Am J Physiol Regul Integr Comp Physiol 2013; 305:R313-21. [PMID: 23720134 DOI: 10.1152/ajpregu.00048.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study examined whether a marked reduction in oxygen delivery, unlike findings in moderate-intensity exercise, would slow leg oxygen uptake (Vo2) kinetics during intense exercise (86 ± 3% of incremental test peak power). Seven healthy males (26 ± 1 years, means ± SE) performed one-legged knee-extensor exercise (60 ± 3 W) for 4 min in a control setting (CON) and with arterial infusion of N(G)-monomethyl-l-arginine and indomethacin in the working leg to reduce blood flow by inhibiting formation of nitric oxide and prostanoids (double blockade; DB). In DB leg blood flow (LBF) and oxygen delivery during the first minute of exercise were 25-50% lower (P < 0.01) compared with CON (LBF after 10 s: 1.1 ± 0.2 vs. 2.5 ± 0.3 l/min and 45 s: 2.7 ± 0.2 vs. 3.8 ± 0.4 l/min) and 15% lower (P < 0.05) after 2 min of exercise. Leg Vo2 in DB was attenuated (P < 0.05) during the first 2 min of exercise (10 s: 161 ± 26 vs. 288 ± 34 ml/min and 45 s: 459 ± 48 vs. 566 ± 81 ml/min) despite a higher (P < 0.01) oxygen extraction in DB. Net leg lactate release was the same in DB and CON. The present study shows that a marked reduction in oxygen delivery can limit the rise in Vo2 during the initial part of intense exercise. This is in contrast to previous observations during moderate-intensity exercise using the same DB procedure, which suggests that fast-twitch muscle fibers are more sensitive to a reduction in oxygen delivery than slow-twitch fibers.
Collapse
Affiliation(s)
- Peter M Christensen
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark
| | | | | | | | | | | | | | | |
Collapse
|
36
|
Lador F, Tam E, Adami A, Kenfack MA, Bringard A, Cautero M, Moia C, Morel DR, Capelli C, Ferretti G. Cardiac output, O2 delivery and kinetics during step exercise in acute normobaric hypoxia. Respir Physiol Neurobiol 2013; 186:206-13. [DOI: 10.1016/j.resp.2013.01.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 01/28/2013] [Accepted: 01/30/2013] [Indexed: 11/28/2022]
|
37
|
Zerbini L, Spencer MD, Grey TM, Murias JM, Kowalchuk JM, Schena F, Paterson DH. Effect of acute hypoxia on muscle blood flow, VO2p, and [HHb] kinetics during leg extension exercise in older men. Eur J Appl Physiol 2013; 113:1685-94. [DOI: 10.1007/s00421-013-2599-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 01/22/2013] [Indexed: 11/30/2022]
|
38
|
Christensen PM, Nordsborg NB, Nybo L, Mortensen SP, Sander M, Secher NH, Bangsbo J. Thigh oxygen uptake at the onset of intense exercise is not affected by a reduction in oxygen delivery caused by hypoxia. Am J Physiol Regul Integr Comp Physiol 2012; 303:R843-9. [DOI: 10.1152/ajpregu.00201.2012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In response to hypoxic breathing most studies report slower pulmonary oxygen uptake (V̇o2) kinetics at the onset of exercise, but it is not known if this relates to an actual slowing of the V̇o2 in the active muscles. The aim of the present study was to evaluate whether thigh V̇o2 is slowed at the onset of intense exercise during acute exposure to hypoxia. Six healthy male subjects (25.8 ± 1.4 yr, 79.8 ± 4.0 kg, means ± SE) performed intense (100 ± 6 watts) two-legged knee-extensor exercise for 2 min in normoxia (NOR) and hypoxia [fractional inspired oxygen concentration (FiO2) = 0.13; HYP]. Thigh V̇o2 was measured by frequent arterial and venous blood sampling and blood flow measurements. In arterial blood, oxygen content was reduced ( P < 0.05) from 191 ± 5 ml O2/l in NOR to 180 ± 5 ml O2/l in HYP, and oxygen pressure was reduced ( P < 0.001) from 111 ± 4 mmHg in NOR to 63 ± 4 mmHg in HYP. Thigh blood flow was the same in NOR and HYP, and thigh oxygen delivery was consequently reduced ( P < 0.05) in HYP, but femoral arterial-venous oxygen difference and thigh V̇o2 were similar in NOR and HYP. In addition, muscle lactate release was the same in NOR and HYP, and muscle lactate accumulation during the first 25 s of exercise determined from muscle biopsy sampling was also similar (0.35 ± 0.07 and 0.36 ± 0.07 mmol·kg dry wt−1·s−1 in NOR and HYP). Thus the increase in thigh V̇o2 was not attenuated at the onset of intense knee-extensor exercise despite a reduction in oxygen delivery and pressure.
Collapse
Affiliation(s)
| | | | - Lars Nybo
- Department of Exercise and Sport Sciences, University of Copenhagen, Denmark
| | | | - Mikael Sander
- The Copenhagen Muscle Research Center and Flight Medicine, Department of Cardiology, Rigshospitalet, Copenhagen, Denmark
| | - Niels H. Secher
- The Copenhagen Muscle Research Center, Department of Anesthesia, Rigshospitaliet, University of Copenhagen, Denmark
| | - Jens Bangsbo
- Department of Exercise and Sport Sciences, University of Copenhagen, Denmark
| |
Collapse
|
39
|
Jones AM, Krustrup P, Wilkerson DP, Berger NJ, Calbet JA, Bangsbo J. Influence of exercise intensity on skeletal muscle blood flow, O2 extraction and O2 uptake on-kinetics. J Physiol 2012; 590:4363-76. [PMID: 22711961 PMCID: PMC3473291 DOI: 10.1113/jphysiol.2012.233064] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 06/15/2012] [Indexed: 11/08/2022] Open
Abstract
Following the start of low-intensity exercise in healthy humans, it has been established that the kinetics of skeletal muscle O(2) delivery is faster than, and does not limit, the kinetics of muscle O(2) uptake (V(O(2)(m))). Direct data are lacking, however, on the question of whether O(2) delivery might limit (V(O(2)(m))) kinetics during high-intensity exercise. Using multiple exercise transitions to enhance confidence in parameter estimation, we therefore investigated the kinetics of, and inter-relationships between, muscle blood flow (Q(m)), a-(V(O(2))) difference and (V(O(2)(m))) following the onset of low-intensity (LI) and high-intensity (HI) exercise. Seven healthy males completed four 6 min bouts of LI and four 6 min bouts of HI single-legged knee-extension exercise. Blood was frequently drawn from the femoral artery and vein during exercise and Q(m), a-(V(O(2))) difference and (V(O(2)(m))) were calculated and subsequently modelled using non-linear regression techniques. For LI, the fundamental component mean response time (MRT(p)) for Q(m) kinetics was significantly shorter than (V(O(2)(m))) kinetics (mean ± SEM, 18 ± 4 vs. 30 ± 4 s; P < 0.05), whereas for HI, the MRT(p) for Q(m) and (V(O(2)(m))) was not significantly different (27 ± 5 vs. 29 ± 4 s, respectively). There was no difference in the MRT(p) for either Q(m) or (V(O(2)(m))) between the two exercise intensities; however, the MRT(p)for a-(V(O(2)) difference was significantly shorter for HI compared with LI (17 ± 3 vs. 28 ± 4 s; P < 0.05). Excess O(2), i.e. oxygen not taken up (Q(m) x (V(O(2))), was significantly elevated within the first 5 s of exercise and remained unaltered thereafter, with no differences between LI and HI. These results indicate that bulk O(2) delivery does not limit (V(O(2)(m))) kinetics following the onset of LI or HI knee-extension exercise.
Collapse
Affiliation(s)
- Andrew M Jones
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Heavitree Road, Exeter, UK.
| | | | | | | | | | | |
Collapse
|
40
|
Zerbini L, Brighenti A, Pellegrini B, Bortolan L, Antonetti T, Schena F. Effects of acute hypoxia on the oxygen uptake kinetics of older adults during cycling exercise. Appl Physiol Nutr Metab 2012; 37:744-52. [DOI: 10.1139/h2012-048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pulmonary oxygen uptake, heart rate (HR), and deoxyhemoglobin (HHb) kinetics were studied in a group of older adults exercising in hypoxic conditions. Fourteen healthy older adults (aged 66 ± 6 years) performed 4 exercise sessions that consisted of (i) an incremental test to exhaustion on a cycloergometer while breathing normoxic room air (fractional inspired oxygen (FiO2) = 20.9% O2); (ii) an incremental test to exhaustion on a cycloergometer while breathing hypoxic room air (FiO2 = 15% O2); (iii) 3 repeated square wave cycling exercises at moderate intensity while breathing normoxic room air; and (iv) 3 repeated square wave cycling exercises at moderate intensity while breathing hypoxic room air. During all exercise sessions, pulmonary gas exchange was measured breath-by-breath; HHb was determined on the vastus lateralis muscle by near-infrared spectroscopy; and HR was collected beat-by-beat. The pulomary oxygen uptake kinetics became slower in hypoxia (31 ± 9 s) than in normoxia (27 ± 7 s) because of an increased mismatching between O2 delivery to O2 utilization at the level of the muscle. The HR and HHb kinetics did not change between hypoxia and normoxia,
Collapse
Affiliation(s)
- Livio Zerbini
- CeRiSM, Centre of Sport Health and Mountain Via Matteo del Ben, 5/b, University of Verona, 38068 Rovereto, Italy
- Faculty of Exercise and Sport Science, University of Verona, Italy
| | - Alfredo Brighenti
- CeRiSM, Centre of Sport Health and Mountain Via Matteo del Ben, 5/b, University of Verona, 38068 Rovereto, Italy
- Faculty of Exercise and Sport Science, University of Verona, Italy
| | - Barbara Pellegrini
- CeRiSM, Centre of Sport Health and Mountain Via Matteo del Ben, 5/b, University of Verona, 38068 Rovereto, Italy
- Faculty of Exercise and Sport Science, University of Verona, Italy
| | - Lorenzo Bortolan
- CeRiSM, Centre of Sport Health and Mountain Via Matteo del Ben, 5/b, University of Verona, 38068 Rovereto, Italy
- Faculty of Exercise and Sport Science, University of Verona, Italy
| | - Tommaso Antonetti
- CeRiSM, Centre of Sport Health and Mountain Via Matteo del Ben, 5/b, University of Verona, 38068 Rovereto, Italy
- Faculty of Exercise and Sport Science, University of Verona, Italy
| | - Federico Schena
- CeRiSM, Centre of Sport Health and Mountain Via Matteo del Ben, 5/b, University of Verona, 38068 Rovereto, Italy
- Faculty of Exercise and Sport Science, University of Verona, Italy
| |
Collapse
|
41
|
McNarry MA, Kingsley MIC, Lewis MJ. Influence of exercise intensity on pulmonary oxygen uptake kinetics in young and late middle-aged adults. Am J Physiol Regul Integr Comp Physiol 2012; 303:R791-8. [PMID: 22855280 DOI: 10.1152/ajpregu.00203.2012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is unclear whether pulmonary oxygen uptake (Vo2) kinetics demonstrate linear, first-order behavior during supra gas exchange threshold exercise. Resolution of this issue is pertinent to the elucidation of the factors regulating oxygen uptake (Vo2) kinetics, with oxygen availability and utilization proposed as putative mediators. To reexamine this issue with the advantage of a relatively large sample size, 50 young (24 ± 4 yr) and 15 late middle-aged (54 ± 3 yr) participants completed repeated bouts of moderate and heavy exercise. Pulmonary gas exchange, heart rate (HR), and cardiac output (Q) variables were measured throughout. The phase II τ was slower during heavy exercise in both young (moderate: 22 ± 9; heavy: 29 ± 9 s; P ≤ 0.001) and middle-aged (moderate: 22 ± 9; heavy: 30 ± 8 s; P ≤ 0.001) individuals. The HR τ was slower during heavy exercise in young (moderate: 33 ± 10; heavy: 44 ± 15 s; P ≤ 0.05) and middle-aged (moderate: 30 ± 12; heavy: 50 ± 20 s; P ≤ 0.05) participants, and the Q τ showed a similar trend (young moderate: 21 ± 13; heavy: 28 ± 16 s; middle-aged moderate: 32 ± 13; heavy: 40 ± 15 s; P ≥ 0.05). There were no differences in primary component Vo2 kinetics between age groups, but the middle-aged group had a significantly reduced Vo2 slow component amplitude in both absolute (young: 0.25 ± 0.09; middle-aged: 0.11 ± 0.06 l/min; P ≤ 0.05) and relative terms (young: 15 ± 10; middle-aged: 9 ± 4%; P ≤ 0.05). Thus Vo2 kinetics do not demonstrate dynamic linearity during heavy intensity exercise. Speculatively, the slower phase II τ during heavy exercise might be attributable to reduced oxygen availability. Finally, the primary and slow components of Vo2 kinetics appear to be differentially influenced by middle age.
Collapse
Affiliation(s)
- Melitta A McNarry
- College of Engineering, Swansea Univ., Singleton Park, Swansea, SA2 8PP, UK.
| | | | | |
Collapse
|
42
|
Lefever J, Berckmans D, Aerts JM. Time-variant modelling of heart rate responses to exercise intensity during road cycling. Eur J Sport Sci 2012; 14 Suppl 1:S406-12. [PMID: 24444235 DOI: 10.1080/17461391.2012.708791] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The aim of this study was to determine if heart rate responses to training intensity during road cycling could be modelled with compact time-variant mathematical model structures. The model performance was evaluated in terms of model order (complexity), number of inputs and parameter estimation methods used (time-invariant vs. time-variant). Thirteen male cyclists performed two identical cycling tests of 27 km on the road. Uphill sections were introduced to induce dynamic variations in heart rate. The heart rate and training intensity, represented by power output and road inclination, were measured in real-time. Taking only power as system input allowed to explain the variations in heart rate in an accurate way R2 T = 0.86 ± 0.08, since adding the road inclination as an additional input did not significantly improve the modelling performance R2 T = 0.87 ± 0.08, P = 0.32. Furthermore, we demonstrated that models with first-order dynamics accurately describes the heart rate responses to power variations R2 T = 0.86 ± 0.08, but that more complex second-order model structures R2 T = 0.88 ± 0.08 were significantly better than the first-order model structures (P = 0.028). Finally, the heart rate dynamics appeared to be time-variant, since the time-variant model structures R2 T = 0.89 ± 0.07 were significantly better than the time-invariant model structures R2 T = 0.84 ± 0.08, P = 0.0002. So, compact time-variant second-order model structures could be used to model the heart rate response to training intensity as a basis for training optimisation.
Collapse
|
43
|
Castello-Simões V, Polaquini Simões R, Beltrame T, Bassi D, Maria Catai A, Arena R, Azambuja NC, do Nascimento Ortega J, Borghi-Silva A. Effects of aerobic exercise training on variability and heart rate kinetic during submaximal exercise after gastric bypass surgery--a randomized controlled trial. Disabil Rehabil 2012; 35:334-42. [PMID: 22725971 DOI: 10.3109/09638288.2012.694575] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND This study aimed to determine whether morbidly obese women have an alteration of heart rate (HR) kinetics and HR variability (HRV) during the 6-min walk test (6MWT) and if an aerobic exercise training can modify these indexes after gastric bypass surgery (GBS). DESIGN AND METHODS Nineteen morbidly obese women were randomized to a trained (TG) or control group and 12 women of eutrophic group (EG) were also evaluated. The obese women were tested on two occasions: 1 week before and 4 months after GBS through record of HR and R-R intervals during 6MWT for analysis HR kinetics. The TG underwent an aerobic exercise training program on a treadmill (1-h session, totaling 36 sessions over 12-week). RESULTS Both obese groups demonstrated a significant reduction of rMSSD and slower HR kinetics during the 6MWT when compared to the EG. In addition, only the TG demonstrated a significant improvement in HRV indexes, walking distance, faster time constant and mean response time of HR during 6MWT after training (p < 0.05). CONCLUSION Morbidly obese women have slower HR kinetics and altered cardiac modulation during submaximal exercise. However, aerobic exercise training can produce beneficial adaptations in HRV and faster HR kinetics following GBS.
Collapse
Affiliation(s)
- Viviane Castello-Simões
- Cardiopulmonary Physiotherapy Laboratory, Nucleus of Research in Physical Exercise, Federal University of São Carlos, São Carlos, São Paulo, Brazil.
| | | | | | | | | | | | | | | | | |
Collapse
|
44
|
De Roia G, Pogliaghi S, Adami A, Papadopoulou C, Capelli C. Effects of priming exercise on the speed of adjustment of muscle oxidative metabolism at the onset of moderate-intensity step transitions in older adults. Am J Physiol Regul Integr Comp Physiol 2012; 302:R1158-66. [DOI: 10.1152/ajpregu.00269.2011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aging is associated with a functional decline of the oxidative metabolism due to progressive limitations of both O2 delivery and utilization. Priming exercise (PE) increases the speed of adjustment of oxidative metabolism during successive moderate-intensity transitions. We tested the hypothesis that such improvement is due to a better matching of O2 delivery to utilization within the working muscles. In 21 healthy older adults (65.7 ± 5 yr), we measured contemporaneously noninvasive indexes of the overall speed of adjustment of the oxidative metabolism (i.e., pulmonary V̇o2 kinetics), of the bulk O2 delivery (i.e., cardiac output), and of the rate of muscle deoxygenation (i.e., deoxygenated hemoglobin, HHb) during moderate-intensity step transitions, either with (ModB) or without (ModA) prior PE. The local matching of O2 delivery to utilization was evaluated by the ΔHHb/ΔV̇o2 ratio index. The overall speed of adjustment of the V̇o2 kinetics was significantly increased in ModB compared with ModA ( P < 0.05). On the contrary, the kinetics of cardiac output was unaffected by PE. At the muscle level, ModB was associated with a significant reduction of the “overshoot” in the ΔHHb/ΔV̇o2 ratio compared with ModA ( P < 0.05), suggesting an improved O2 delivery. Our data are compatible with the hypothesis that, in older adults, PE, prior to moderate-intensity exercise, beneficially affects the speed of adjustment of oxidative metabolism due to an acute improvement of the local matching of O2 delivery to utilization.
Collapse
Affiliation(s)
- Gabriela De Roia
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, School of Human Movement Sciences, University of Verona, Italy; and
| | - Silvia Pogliaghi
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, School of Human Movement Sciences, University of Verona, Italy; and
| | - Alessandra Adami
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, School of Human Movement Sciences, University of Verona, Italy; and
- Department of Basic Neurosciences, School of Medicine, Geneva, Switzerland
| | - Christina Papadopoulou
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, School of Human Movement Sciences, University of Verona, Italy; and
| | - Carlo Capelli
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, School of Human Movement Sciences, University of Verona, Italy; and
| |
Collapse
|
45
|
Spencer MD, Murias JM, Grey TM, Paterson DH. Regulation of V̇o2 kinetics by O2 delivery: insights from acute hypoxia and heavy-intensity priming exercise in young men. J Appl Physiol (1985) 2012; 112:1023-32. [PMID: 22194321 DOI: 10.1152/japplphysiol.01215.2011] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study examined the separate and combined effects of acute hypoxia (Hypo) and heavy-intensity “priming” exercise (Hvy) on pulmonary O2 uptake (V̇o2p) kinetics during moderate-intensity exercise (Mod). Breath-by-breath V̇o2p and near-infrared spectroscopy-derived muscle deoxygenation {deoxyhemoglobin concentration [HHb]} were monitored continuously in 10 men (23 ± 4 yr) during repetitions of a Mod 1-Hvy-Mod 2 protocol, where each of the 6-min (Mod or Hvy) leg-cycling bouts was separated by 6 min at 20 W. Subjects were exposed to Hypo [fraction of inspired O2 (FiO2) = 15%, Mod 2 + Hypo] or “sham” (FiO2 = 20.9%, Mod 2-N) 2 min following Hvy in half of these repetitions; Mod was also performed in Hypo without Hvy (Mod 1 + Hypo). On-transient V̇o2p and [HHb] responses were modeled as a monoexponential. Data were scaled to a relative percentage of the response (0–100%), the signals were time-aligned, and the individual [HHb]-to-V̇o2 ratio was calculated. Compared with control (Mod 1), τV̇o2p and the O2 deficit (26 ± 7 s and 638 ± 144 ml, respectively) were reduced ( P < 0.05) in Mod 2-N (20 ± 5 s and 529 ± 196 ml) and increased ( P < 0.05) in Mod 1 + Hypo (34 ± 14 s and 783 ± 184 ml); in Mod 2 + Hypo, τV̇o2p was increased (30 ± 8 s, P < 0.05), yet O2 deficit was unaffected (643 ± 193 ml, P > 0.05). The modest “overshoot” in the [HHb]-to-V̇o2 ratio (reflecting an O2 delivery-to-utilization mismatch) in Mod 1 (1.06 ± 0.04) was abolished in Mod 2-N (1.00 ± 0.05), persisted in Mod 2 + Hypo (1.09 ± 0.07), and tended to increase in Mod 1 + Hypo (1.10 ± 0.09, P = 0.13). The present data do not support an “O2 delivery-independent” speeding of τV̇o2p following Hvy (or Hvy + Hypo); rather, this study suggests that local muscle O2 delivery likely governs the rate of adjustment of V̇o2 at τV̇o2p greater than ∼20 s.
Collapse
Affiliation(s)
- Matthew D. Spencer
- Canadian Centre for Activity and Aging and
- School of Kinesiology, University of Western Ontario, London, Ontario, Canada
| | - Juan M. Murias
- Canadian Centre for Activity and Aging and
- School of Kinesiology, University of Western Ontario, London, Ontario, Canada
| | - Tyler M. Grey
- School of Kinesiology, University of Western Ontario, London, Ontario, Canada
| | - Donald H. Paterson
- Canadian Centre for Activity and Aging and
- School of Kinesiology, University of Western Ontario, London, Ontario, Canada
| |
Collapse
|
46
|
Exercise intolerance at high altitude (5050m): Critical power and W′. Respir Physiol Neurobiol 2011; 177:333-41. [DOI: 10.1016/j.resp.2011.05.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 05/12/2011] [Accepted: 05/13/2011] [Indexed: 11/19/2022]
|
47
|
Oxygen uptake, cardiac output and muscle deoxygenation at the onset of moderate and supramaximal exercise in humans. Eur J Appl Physiol 2010; 111:1517-27. [DOI: 10.1007/s00421-010-1786-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Accepted: 12/12/2010] [Indexed: 10/18/2022]
|
48
|
Keyser RE, Rus V, Mikdashi JA, Handwerger BS. Exploratory study on oxygen consumption on-kinetics during treadmill walking in women with systemic lupus erythematosus. Arch Phys Med Rehabil 2010; 91:1402-9. [PMID: 20801259 DOI: 10.1016/j.apmr.2010.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 05/28/2010] [Accepted: 06/02/2010] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To determine whether oxygen consumption (V o(2)) on-kinetics differed between groups of women with systemic lupus erythematosus (SLE) and sedentary but otherwise healthy controls. DESIGN Exploratory case-control study. SETTING Medical school exercise physiology laboratory. PARTICIPANTS Convenience samples of women with SLE (n=12) and sedentary but otherwise healthy controls (n=10). INTERVENTION None. MAIN OUTCOME MEASURES V o(2) on-kinetics indices including time to steady state, rate constant, mean response time (MRT), transition constant, and oxygen deficit measured during bouts of treadmill walking at intensities of 3 and 5 metabolic equivalents (METs). RESULTS Time to steady state and oxygen deficit were increased and rate constant was decreased in the women with SLE compared with controls. At the 5-MET energy demand, the transition constant was lower and MRT was longer in the women with SLE than in controls. For a similar relative energy expenditure that was slightly lower than the anaerobic threshold, the transition constant was higher in controls than in women with SLE. CONCLUSION V o(2) on-kinetics was prolonged in women with SLE. The prolongation was concomitant with an increase in oxygen deficit and may underlie performance fatigability in women with SLE.
Collapse
|
49
|
Mendonca GV, Pereira FD, Fernhall B. Oxygen uptake kinetics during exercise in adults with Down syndrome. Eur J Appl Physiol 2010; 110:575-83. [PMID: 20559651 DOI: 10.1007/s00421-010-1540-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2010] [Indexed: 10/19/2022]
Abstract
Persons with Down syndrome (DS) have diminished submaximal and peak work capacity. This study evaluated the dynamic response of oxygen uptake at onset and recovery (VO(2) kinetics) of constant-load exercise (moderate intensity 45% VO(2peak)) in adults with DS. A total of 27 healthy participants aged 18-50 years performed graded treadmill exercise to assess peak VO(2): 14 with DS (9 males and 5 females) and 13 controls without disabilities (9 males and 4 females). Subjects also performed constant-load exercise tests at 45% VO(2peak) to determine VO(2) on-transient and VO(2) off-transient responses. Peak VO(2) was lower in participants with DS as compared to controls (DS 30.2 ± 7.1; controls 46.1 ± 9.6 mL kg(-1) min(-1), P < 0.05). In contrast, at 45% VO(2peak), the time constants for the VO(2) on-transients (DS 34.6 ± 9.1; controls 37.6 ± 9.0 s) and VO(2) off-transients (DS 36.5 ± 12.3; controls 37.7 ± 7.0 s) were not significantly different between the groups. Additionally, there were no differences between on-transient and off-transient time constants in participants with DS or controls. These data demonstrate that the VO(2) kinetics at onset and recovery of moderate intensity exercise is similar between adults with DS and controls. Therefore, the submaximal exercise performance of these individuals is not affected by slowed VO(2) kinetics.
Collapse
Affiliation(s)
- Goncalo V Mendonca
- Center of Human Performance CIPER, Estrada da Costa, Cruz Quebrada, Faculty of Human Kinetics, Technical University of Lisbon, Cruz Quebrada Dafundo, 1495-688 Lisbon, Portugal.
| | | | | |
Collapse
|
50
|
|