Effect of exercise intensity, duration and mode on post-exercise oxygen consumption

THE EFFECT OF HIGH-INTENSITY INTERVAL TRAINING ON POST-EXERCISE OXYGEN CONSUMPTION: A META-ANALYSIS

ABSTRACT Introduction: The objective of this study was to present a systematic review and meta-analysis to compare total excess post-exercise oxygen consumption (EPOC) for two training intervention models in healthy individuals, and the secondary objective was to understand whether oxygen consumption after exercise could really promote a meaningful help. Design: To design a meta-analysis review to compare two training intervention models (experimental: high-intensity interval training; and control: continuous moderate-intensity) and their effects on total EPOC in healthy individuals. Participants: Seventeen studies were considered to be of good methodological quality and with a low risk of bias. Methods: Literature searches were performed using the electronic databases with no restriction on year of publication. The keywords used were obtained by consulting Mesh Terms (PubMed) and DeCS (BIREME Health Science Descriptors). Results: The present study findings showed a tendency (random-effects model: 0.87, 95%-CI [0.35,1.38], I2=73%, p<0.01) to increase EPOC when measured following high-intensity interval training. Conclusions: Our study focused on the analysis of high- and moderate-intensity oxygen uptake results following exercise. Despite the growing popularity of high-intensity interval training, we found that the acute and chronic benefits remain limited. We understand that the lack of a standard protocol and standard training variables provides limited consensus to determine the magnitude of the EPOC. We suggest that longitudinal experimental studies may provide more robust conclusions. Another confounding factor in the studies investigated was the magnitude (time in minutes) of VO2 measurements when assessing EPOC. Measurement times ranged from 60 min to 720 min. Longitudinal studies and controlled experimental designs would facilitate more precise measurements and correct subject numbers would provide accurate effect sizes. Systematic reviewb of Level II studies.

The Influence of Physical Exercise Frequency and Intensity on Individual Entrepreneurial Behavior: Evidence from China

Physical exercise can benefit individuals' physical and mental health and also influence individuals' long-term behavioral choices. Doing exercise is particularly important given that physical exercise can impact individuals' cognitive abilities and positive emotional states, which may further impact entrepreneurial behavior. Therefore, understanding the relationship between exercise and entrepreneurial behavior is essential, because it can provide policy suggestions for popularizing athletic activities and boosting entrepreneurship. Consequently, the present study examined whether physical exercise could predict entrepreneurial behavior and the possible psychological mechanisms within this relationship. Based on the 2017 Chinese General Social Survey (CGSS2017), this study tested the hypotheses using the Probit and Tobit models. The results showed that individuals' physical exercise intensity and frequency positively affected their entrepreneurial behavior. In addition, five variables moderated the relationships between physical exercise and individual entrepreneurial behavior: urban-rural differences, education level, marital status, the existence of minor children, and age. Moreover, positive emotions and physical/mental health mediated the influence of physical exercise (exercise frequency and exercise intensity) on individual entrepreneurial behavior. Endogeneity explanations were ruled out by including instrumental variable, copula terms and adopting coarsened exact matching.

Noncontact Longitudinal Respiratory Rate Measurements in Healthy Adults Using Radar-Based Sleep Monitor (Somnofy): Validation Study

BACKGROUND

Respiratory rate (RR) is arguably the most important vital sign to detect clinical deterioration. Change in RR can also, for example, be associated with the onset of different diseases, opioid overdoses, intense workouts, or mood. However, unlike for most other vital parameters, an easy and accurate measuring method is lacking.

OBJECTIVE

This study aims to validate the radar-based sleep monitor, Somnofy, for measuring RRs and investigate whether events affecting RR can be detected from personalized baselines calculated from nightly averages.

METHODS

First, RRs from Somnofy for 37 healthy adults during full nights of sleep were extensively validated against respiratory inductance plethysmography. Then, the night-to-night consistency of a proposed filtered average RR was analyzed for 6 healthy participants in a pilot study in which they used Somnofy at home for 3 months.

RESULTS

Somnofy measured RR 84% of the time, with mean absolute error of 0.18 (SD 0.05) respirations per minute, and Bland-Altman 95% limits of agreement adjusted for repeated measurements ranged from -0.99 to 0.85. The accuracy and coverage were substantially higher in deep and light sleep than in rapid eye movement sleep and wake. The results were independent of age, sex, and BMI, but dependent on supine sleeping position for some radar orientations. For nightly filtered averages, the 95% limits of agreement ranged from -0.07 to -0.04 respirations per minute. In the longitudinal part of the study, the nightly average was consistent from night to night, and all substantial deviations coincided with self-reported illnesses.

CONCLUSIONS

RRs from Somnofy were more accurate than those from any other alternative method suitable for longitudinal measurements. Moreover, the nightly averages were consistent from night to night. Thus, several factors affecting RR should be detectable as anomalies from personalized baselines, enabling a range of applications. More studies are necessary to investigate its potential in children and older adults or in a clinical setting.

Variations in cost of transport and their ecological consequences: a review

Movement is essential in the ecology of most animals, and it typically consumes a large proportion of individual energy budgets. Environmental conditions modulate the energetic cost of movement (cost of transport, COT), and there are pronounced differences in COT between individuals within species and across species. Differences in morphology affect COT, but the physiological mechanisms underlying variation in COT remain unresolved. Candidates include mitochondrial efficiency and the efficiency of muscle contraction-relaxation dynamics. Animals can offset increased COT behaviourally by adjusting movement rate and habitat selection. Here, we review the theory underlying COT and the impact of environmental changes on COT. Increasing temperatures, in particular, increase COT and its variability between individuals. Thermal acclimation and exercise can affect COT, but this is not consistent across taxa. Anthropogenic pollutants can increase COT, although few chemical pollutants have been investigated. Ecologically, COT may modify the allocation of energy to different fitness-related functions, and thereby influence fitness of individuals, and the dynamics of animal groups and communities. Future research should consider the effects of multiple stressors on COT, including a broader range of pollutants, the underlying mechanisms of COT and experimental quantifications of potential COT-induced allocation trade-offs.

High-intensity interval training with or without chlorella vulgaris supplementation in obese and overweight women: effects on mitochondrial biogenesis, performance and body composition

The beneficial effects of high-intensity interval training (HIIT) and chlorella vulgaris (CV) on body composition and mitochondrial biogenesis have been shown in some mechanistic studies. This study aimed to determine the effects of CV and/or HIIT on mitochondrial biogenesis, performance and body composition among overweight/obese women. There was a significant reduction in the fat mass (FM) of the CV + HIIT group, as compared with the placebo group (P = 0·005). A marginal significant increase in body water (P = 0·050) and PPAR-γ coactivator-1α (P = 0·050) was also found only in the CV + HIIT group, as compared with the placebo. Relative (P < 0·001) and absolute (P < 0·001) VO_2max, as well as Bruce MET (P < 0·001), were significantly increased in the HIIT and HIIT + CV groups. Besides, the synergistic effect of CV and HIIT on the Bruce MET increment was found (interaction P-value = 0·029). No significant changes were observed in BMI, fat-free mass, visceral fat, silent information regulator 1 and fibroblast growth factor-21. In this randomised clinical trial, forty-six overweight/obese women were assigned to four groups including CV + HIIT and HIIT + placebo groups that received three capsules of CV (300 mg capsules, three times a day) or corn starch, in combination with three sessions/week of HIIT. CV and placebo groups only received 900 mg of CV or corn starch, daily, for 8 weeks. Biochemical assessments, performance assessment and body composition were obtained at the beginning and end of the intervention. HIIT may be, therefore, effective in improving mitochondrial biogenesis, performance and body composition in overweight/obese women.

Complex Network Model Reveals the Impact of Inspiratory Muscle Pre-Activation on Interactions among Physiological Responses and Muscle Oxygenation during Running and Passive Recovery

Simple Summary

Different warm-ups can be used to improve physical and sports performance. Among these strategies, we can include the pre-activation of the inspiratory muscles. Our study aimed to investigate this pre-activation model in high-intensity running performance and recovery using an integrative computational analysis called a complex network. The participants in this study underwent four sessions. The first and second sessions were performed to explain the procedures, characterize them and determine the individualized pre-activation intensity (40% of the maximum inspiratory pressure). Subsequently, on different days, the subjects were submitted to high-intensity tethered runs on a non-motorized treadmill with monitoring of the physiological responses during and after this effort. To understand the impacts of the pre-activation of inspiratory muscles on the organism, we studied the centrality metrics obtained by complex networks, which help in the interpretation of data in a more integrated way. Our results revealed that the graphs generated by this analysis were altered when inspiratory muscle pre-activation was applied, emphasizing muscle oxygenation responses in the leg and arm. Blood lactate also played an important role, especially after our inspiratory muscle strategy. Our findings confirm that the pre-activation of inspiratory muscles promotes modulations in the organism, better integrating physiological responses, which could increase performance and improve recovery.

Abstract

Although several studies have focused on the adaptations provided by inspiratory muscle (IM) training on physical demands, the warm-up or pre-activation (PA) of these muscles alone appears to generate positive effects on physiological responses and performance. This study aimed to understand the effects of inspiratory muscle pre-activation (IM_PA) on high-intensity running and passive recovery, as applied to active subjects. In an original and innovative investigation of the impacts of IM_PA on high-intensity running, we proposed the identification of the interactions among physical characteristics, physiological responses and muscle oxygenation in more and less active muscle to a running exercise using a complex network model. For this, fifteen male subjects were submitted to all-out 30 s tethered running efforts preceded or not preceded by IM_PA, composed of 2 × 15 repetitions (1 min interval between them) at 40% of the maximum individual inspiratory pressure using a respiratory exercise device. During running and recovery, we monitored the physiological responses (heart rate, blood lactate, oxygen saturation) and muscle oxygenation (in vastus lateralis and biceps brachii) by wearable near-infrared spectroscopy (NIRS). Thus, we investigated four scenarios: two in the tethered running exercise (with or without IM_PA) and two built into the recovery process (after the all-out 30 s), under the same conditions. Undirected weighted graphs were constructed, and four centrality metrics were analyzed (Degree, Betweenness, Eigenvector, and Pagerank). The IM_PA (40% of the maximum inspiratory pressure) was effective in increasing the peak and mean relative running power, and the analysis of the complex networks advanced the interpretation of the effects of physiological adjustments related to the IM_PA on exercise and recovery. Centrality metrics highlighted the nodes related to muscle oxygenation responses (in more and less active muscles) as significant to all scenarios, and systemic physiological responses mediated this impact, especially after IM_PA application. Our results suggest that this respiratory strategy enhances exercise, recovery and the multidimensional approach to understanding the effects of physiological adjustments on these conditions.

Accuracy of Tracking Devices' Ability to Assess Exercise Energy Expenditure in Professional Female Soccer Players: Implications for Quantifying Energy Availability

The purpose of the study was to assess the accuracy of commonly used GPS/accelerometer-based tracking devices in the estimation of exercise energy expenditure (EEE) during high-intensity intermittent exercise. A total of 13 female soccer players competing at the highest level in Norway (age 20.5 ± 4.3 years; height 168.4 ± 5.1 cm; weight 64.1 ± 5.3 kg; fat free mass 49.7 ± 4.2 kg) completed a single visit test protocol on an artificial grass surface. The test course consisted of walking, jogging, high-speed running, and sprinting, mimicking the physical requirements in soccer. Three commonly used tracking devices were compared against indirect calorimetry as the criterion measure to determine their accuracy in estimating the total energy expenditure. The anaerobic energy consumption (i.e., excess post-exercise oxygen consumption, EPOC) and resting time were examined as adjustment factors possibly improving accuracy. All three devices significantly underestimated the total energy consumption, as compared to the criterion measure (p = 0.022, p = 0.002, p = 0.017; absolute ICC = 0.39, 0.24 and 0.30, respectively), and showed a systematic pattern with increasing underestimation for higher energy consumption. Excluding EPOC from EEE reduced the bias substantially (all p's becoming non-significant; absolute ICC = 0.49, 0.54 and 0.49, respectively); however, bias was still present for all tracking devices. All GPS trackers were biased by showing a general tendency to underestimate the exercise energy consumption during high intensity intermittent exercising, which in addition showed a systematic pattern by over- or underestimation during lower or higher exercising intensity. Adjusting for EPOC reduced the bias and provided a more acceptable accuracy. For a more correct EEE estimation further calibration of these devices by the manufacturers is strongly advised by possibly addressing biases caused by EPOC.

Exercise duration: Independent effects on acute physiologic responses and the need for an individualized prescription

An individualization of exercise prescription is implemented mainly in terms of intensity but not for duration. To survey the need for an individualized exercise duration prescription, we investigated acute physiologic responses during constant‐load exercise of maximal duration (t_max) and determined so‐called duration thresholds. Differences between absolute (min) and relative terms (% t_max) of exercise duration were analyzed. Healthy young and trained male and female participants (n = 11) performed an incremental exercise test and one t_max constant‐load exercise test at a target intensity of 10% of maximal power output below the second lactate turn point (LTP₂). Blood lactate, heart rate, and spirometric data were measured during all tests. t_max was markedly different across subjects (69.6 ± 14.8 min; range: 40–90 min). However, distinct duration phases separated by duration thresholds (DTh) were found in most measured variables. These duration thresholds (except DTh1) were significantly related to t_max (DTh2: r² = 0.90, p < 0.0001; DTh3: r² = 0.98, p < 0.0001) and showed substantial interindividual differences if expressed in absolute terms (DTh2: 24.8 ± 6.0 min; DTh3: 47.4 ± 10.6 min) but not in relative terms (DTh2: 35.4 ± 2.7% t_max; DTh3: 67.9 ± 2.4% t_max). Our data showed that (1) maximal duration was individually different despite the same relative intensity, (2) duration thresholds that were related to t_max could be determined in most measured variables, and (3) duration thresholds were comparable between subjects if expressed in relative terms. We therefore conclude that duration needs to be concerned as an independent variable of exercise prescription.

The high-intensity interval training introduced in physical education lessons decrease systole in high blood pressure adolescents

Increased resting blood pressure (BP) is a risk factor for many health complications. The prevalence of elevated BP is growing among adolescents. There is a need to investigate effective ways of decreasing excessive blood pressure in this age group. The study aim was to determine the effect of 10-weeks High-Intensive Interval Training (HIIT)—Tabata protocol—introduced in physical education (PE) lessons on resting blood pressure in adolescents. The sample included 52 boys aged 16.23 ± 0.33 years body height176.74 ± 6.07 (m), body weight 65.42 ± 12.51 (kg), BMI 20.89 ± 3.53 (kg/m²) and 89 girls aged 16.12 ± 0.42 years, body height 164.38 ± 6.54 (m), body weight 56.71 ± 10.23 (kg), BMI 20.93 ± 3.08 (kg/m²) from secondary school. Based on resting BP, the fractions of boys and girls with normal BP and high BP were identified and divided into experimental (EG) and control (CG) groups. EG completed a 10-weeks HIIT program (three cycles of Tabata protocol) implemented in one PE lesson during a week. The duration of the effort was 14 min. The intensity was at 75–80% of maximal heart rate. Changes in systolic and diastolic BP after the experiment were examined. The results indicated the improvement in SBP in EG with high BP compared to the rest of the groups (average reduction of 12.77 mmHg; p < 0.0001). The EG normotensive had a statistically significant higher reduction of SBP comparing CG normotensive (average decrease of 1.81 mmHG; p = 0.0089). HIIT effectively decreases BP in adolescents. Implementing HIIT in PE lessons in secondary school is recommended to improve BP parameters.

Motivation and Eco-Attitudes among Night Runners during the COVID-19 Pandemic

Running surrounded by nature at night, often with limited contact with other people, is one of the safest physical activities during the COVID-19 pandemic. The aim of this article is to determine what motivates night recreational runners and to analyse the differences between men and women according to age, and also to see whether the fact of having had COVID-19 or not matters when it comes to athletes’ motivation behind participating in runs. Runners were also asked about participating in cities or out-of-town events in terms of verifying the cleanliness of the air before running, using masks or running in green areas. 233 individuals in total participated in this descriptive, quantitative, cross-sectional study. The questionnaire uses the division of motives used in the Marathon Motivation Scale (MOMS) and a number of additional questions on environmental factors. Overall, the main motivation that drives night-time runners is health orientation, weight concern, personal goal achievement, psychological coping, life meaning and self-esteem. The research also showed higher scores for health orientation, recognition, psychological coping, life meaning and self-esteem among runners who had had COVID-19 than runners who had not had the virus. In addition, respondents clearly indicated that night running makes it easier to fall asleep and improves the quality of sleep. Most runners rated their mental health as being good, did not run in the morning despite better air levels, did not choose running events outside the urban area and did not check the air quality index before running. Therefore, it will be important for coaches, event organisers and other professionals to consider athletes’ age, gender, whether they have had COVID-19 and runners’ approaches to eco-attitudes when trying to understand their reasons for participating in different sports or leisure events, especially those that focus on a priority in shaping environmental attitudes.

Virtual diabetic patient with physical activity dynamics

BACKGROUND AND OBJECTIVE

Diabetes is a disease of impaired blood glucose regulation due to the absence or insufficient secretion of insulin hormone or insulin resistance induced in the human body. In literature, the impact of exercise is considered in few models based on the minimal representation of glucose dynamics along with the assumption that no endogenous insulin is produced in the body. Hence these models are not capable of describing diabetic behavior which is independent of exogenous insulin. This type of diabetes, known as type-2, affects almost 90% of the total diabetes population. In this article, a constraint-based comprehensive physiological model of blood glucose dynamics is aimed to build for filling up the gap in the literature.

METHODS

For physiological comprehensiveness, the model is considered to consist of several compartments separately connected with a common compartment named 'plasma'. Plasma is the only accessible compartment and contains the state variables. Plasma variables are the integrated result of the net change in rates of metabolic processes and basal rates are influenced between two saturation constraints for an operating range of each plasma variable. The influence of a plasma variable on a metabolic rate is represented using a form of the hyperbolic tangent function. Validation is done by fitting the model with clinical experiments and continuous glucose monitoring data of a free-living environment.

RESULTS

The proposed model generates an average correlation coefficient of 0.85 ± 0.13 on all simulated responses with the target in the fitting experiments. Besides this, the model can produce a spectrum of metabolic effects of plasma variables for showing more insight into glucose metabolism.

CONCLUSIONS

A constraint-based comprehensive glucose regulation with exercise dynamics for modeling diabetes is pursued. The model doesn't consider age, gender, physical, and mental condition of the human body but can be applied in operation research by mathematical programming.

Acute Behavior of Oxygen Consumption, Lactate Concentrations, and Energy Expenditure During Resistance Training: Comparisons Among Three Intensities

Purpose: This study aimed to compare the oxygen consumption, lactate concentrations, and energy expenditure using three different intensities during the resistance training sessions.

Methods: A total of 15 men (22.9 ± 2.61 years) experienced in resistance training underwent 3 sessions composed of 8 exercises (chest press, pec deck, squat, lat pull-down, biceps curl, triceps extension, hamstring curl, and crunch machine), which were applied in the same order. The weight lifted differed among the sessions [high session: 6 sets of 5 repetitions at 90% of 1-repetition maximum (1-RM); intermediary session: 3 sets of 10 repetitions at 75% of 1-RM; and low session: 2 sets of 15 repetitions at 60% of 1-RM]. The oxygen consumption (VO₂)—during and after (excess post-exercise oxygen consumption (EPOC)) the session, blood lactate concentration, and energy expenditure (i.e., the sum of aerobic and anaerobic contributions, respectively) were assessed.

Results: The VO2 significantly decreased in the function of the weight lifting (F_(2.28) = 17.02; p < 0.01; ηG2 = 0.32). However, the aerobic contributions significantly increase in the function of the weight lifting (F_(2.28) = 79.18; p < 0.01; ηG2 = 0.75). The anaerobic contributions were not different among the sessions (p > 0.05; ηG2 < 0.01). Thus, the total energy expenditure during the session (kcal) significantly increased in the function of the weight lifting (F_(2.28) = 86.68; p < 0.01; ηG2 = 0.75). The energy expenditure expressed in time unit (kcal·min⁻¹) was higher in low session than in high session (F_(2.28) = 6.20; p < 0.01; ηG2 = 0.15).

Conclusion: The weight lifted during resistance training-induced different physiological responses, which induced higher energy expenditure per unit of time during the low session.

The active grandparent hypothesis: Physical activity and the evolution of extended human healthspans and lifespans

The proximate mechanisms by which physical activity (PA) slows senescence and decreases morbidity and mortality have been extensively documented. However, we lack an ultimate, evolutionary explanation for why lifelong PA, particularly during middle and older age, promotes health. As the growing worldwide epidemic of physical inactivity accelerates the prevalence of noncommunicable diseases among aging populations, integrating evolutionary and biomedical perspectives can foster new insights into how and why lifelong PA helps preserve health and extend lifespans. Building on previous life-history research, we assess the evidence that humans were selected not just to live several decades after they cease reproducing but also to be moderately physically active during those postreproductive years. We next review the longstanding hypothesis that PA promotes health by allocating energy away from potentially harmful overinvestments in fat storage and reproductive tissues and propose the novel hypothesis that PA also stimulates energy allocation toward repair and maintenance processes. We hypothesize that selection in humans for lifelong PA, including during postreproductive years to provision offspring, promoted selection for both energy allocation pathways which synergistically slow senescence and reduce vulnerability to many forms of chronic diseases. As a result, extended human healthspans and lifespans are both a cause and an effect of habitual PA, helping explain why lack of lifelong PA in humans can increase disease risk and reduce longevity.

Acute and chronic effects of high-intensity interval training (HIIT) on postexercise intramuscular lipid metabolism in rats

Recovery from exercise refers to the period between the end of a bout of exercise and the subsequent return to a resting or recovered state. It is a dynamic period in which many physiological changes occur. A large amount of research has evaluated the effect of training on intramuscular lipid metabolism. However, data are limited regarding intramuscular lipid metabolism during the recovery period. In this study, lipid metabolism-related proteins were examined after a single bout of exercise in a time-dependent way to explore the mechanism of how exercise induces intramuscular lipid metabolism adaptation. Firstly, all rats in the exercise group underwent a five-week training protocol (HIIT, five times/week), and then performed a more intense HIIT session after 72 h of the last-time five-week training. After that, rats were sampled in a time-dependent way, including 0 h, 6 h, 12 h, 24 h, 48 h, 72 h, and 96 h following the acute training session. Our results discovered that five weeks of HIIT increased the content of intramuscular triglyceride (IMTG) and enhanced the lipolytic and lipogenesis-related proteins in skeletal muscle. Furthermore, IMTG content decreased immediately post HIIT and gradually increased to baseline levels 48 h postexercise, continuing to over-recover up to 96 h postexercise. Following acute exercise, lipolytic-related proteins showed an initial increase (6-12 h) before decreasing during recovery. Conversely, lipogenesis-related proteins decreased following exercise (6-12 h), then increased in the recovery period. Based on the changes, we speculate that skeletal muscle is predominated by lipid oxidative at the first 12 h postexercise. After this period, lipid synthesis-related proteins increased, which may be the result of body recovery. Together, these results may provide insight into how the lipid metabolism-related signaling changes after chronic and acute HIIT and how protein levels lipid metabolism correlates to IMTG recovery.

Historical body temperature records as a population-level 'thermometer' of physical activity in the United States

Over the past two centuries profound technological and social changes have reduced overall levels of physical activity (PA). However, just how much population-level PA levels have declined since the Industrial Revolution is unknown because methods for measuring PA, such as accelerometry and the doubly labeled water technique, were developed only within the last few decades. Here, we show that historical records of resting body temperature (T_B) can serve as a 'thermometer' of population-level PA, enabling us to use the well-documented secular decline in T_B in the US¹ to approximate PA decline in the US since 1820. Using cross-sectional data relating T_B to resting metabolic rate (RMR) and RMR to PA, we estimate that RMR has declined by ∼6% and moderate to vigorous PA by ∼27 minutes per day since 1820 in the US.

Inclusion of sprints during moderate-intensity continuous exercise enhances post-exercise fat oxidation in young males

To assess the physiological demand of including high-intensity efforts during continuous exercise, we designed a randomized crossover study, where 12 physically active young males executed three different exercises in random order: FATmax - continuous exercise at the highest fat oxidation zone (FATmax); 2min-130% - FATmax interspersed by a 2-min bout at 130% of the maximal oxygen uptake associated intensity (iV̇O2max); and 20s:10s-170% - FATmax interspersed by four 20-s bouts at 170%iV̇O2max interpolated by 10s of passive recovery. We measured oxygen uptake (V̇O2), blood lactate concentration ([LAC]), respiratory exchange rate (RER), fat and carbohydrate (CHO) oxidation. For statistical analyses, repeated measures ANOVA was applied. Although no differences were found for average V̇O2 or carbohydrate oxidation rate, the post-exercise fat oxidation rate was 37.5% and 50% higher during 2min-130% and 20s:10s-170%, respectively, compared to FATmax, which also presented lower values of RER during exercise compared to 2min-130% and 20s:10s-170% (p<0.001 in both), and higher values post-exercise (p=0.04 and p=0.002, respectively). The [LAC] was higher during exercise when high-intensity bouts were applied (p<0.001 for both) and higher post-exercise on the intermittent one compared to FATmax (p=0.016). The inclusion of high-intensity efforts during moderate-intensity continuous exercise promoted higher physiological demand and post-exercise fat oxidation. Novelty bullets • The inclusion of 2-min efforts modifies continuous exercise demands • Maximal efforts can increase post-exercise fat oxidation • 2-min maximal efforts, continuous or intermittent, presents similar demands.

The Effect of Resistance Training in Healthy Adults on Body Fat Percentage, Fat Mass and Visceral Fat: A Systematic Review and Meta-Analysis

BACKGROUND

Resistance training is the gold standard exercise mode for accrual of lean muscle mass, but the isolated effect of resistance training on body fat is unknown.

OBJECTIVES

This systematic review and meta-analysis evaluated resistance training for body composition outcomes in healthy adults. Our primary outcome was body fat percentage; secondary outcomes were body fat mass and visceral fat.

DESIGN

Systematic review with meta-analysis.

DATA SOURCES

We searched five electronic databases up to January 2021.

ELIGIBILITY CRITERIA

We included randomised trials that compared full-body resistance training for at least 4 weeks to no-exercise control in healthy adults.

ANALYSIS

We assessed study quality with the TESTEX tool and conducted a random-effects meta-analysis, with a subgroup analysis based on measurement type (scan or non-scan) and sex (male or female), and a meta-regression for volume of resistance training and training components.

RESULTS

From 11,981 records, we included 58 studies in the review, with 54 providing data for a meta-analysis. Mean study quality was 9/15 (range 6-15). Compared to the control, resistance training reduced body fat percentage by - 1.46% (95% confidence interval - 1.78 to - 1.14, p < 0.0001), body fat mass by - 0.55 kg (95% confidence interval - 0.75 to - 0.34, p < 0.0001) and visceral fat by a standardised mean difference of - 0.49 (95% confidence interval - 0.87 to - 0.11, p = 0.0114). Measurement type was a significant moderator in body fat percentage and body fat mass, but sex was not. Training volume and training components were not associated with effect size. Resistance training reduces body fat percentage, body fat mass and visceral fat in healthy adults.

STUDY REGISTRATION

osf.io/hsk32.

Variations in Elite Female Soccer Players' Sleep, and Associations With Perceived Fatigue and Soccer Games

The current study investigated the associations between female perceived fatigue of elite soccer players and their sleep, and the associations between the sleep of players and soccer games. The sample included 29 female elite soccer players from the Norwegian national soccer team with a mean age of ~26 years. Perceived fatigue and sleep were monitored over a period of 124 consecutive days. In this period, 12.8 ± 3.9 soccer games per player took place. Sleep was monitored with an unobtrusive impulse radio ultra-wideband Doppler radar (Somnofy). Perceived fatigue was based on a self-report mobile phone application that detected daily experienced fatigue. Multilevel analyses of day-to-day associations showed that, first, increased perceived fatigue was associated with increased time in bed (3.6 ± 1.8 min, p = 0.037) and deep sleep (1.2 ± 0.6 min, p = 0.007). Increased rapid eye movement (REM) sleep was associated with subsequently decreased perceived fatigue (−0.21 ± 0.08 arbitrary units [AU], p = 0.008), and increased respiration rate in non-REM sleep was associated with subsequently increased fatigue (0.27 ± 0.09 AU, p = 0.002). Second, game night was associated with reduced time in bed (−1.0 h ± 8.4 min, p = <0.001), total sleep time (−55.2 ± 6.6 min, p = <0.001), time in sleep stages (light: −27.0 ± 5.4 min, p = <0.001; deep: −3.6 ± 1.2 min, p = 0.001; REM: −21.0 ± 3.0 min, p = <0.001), longer sleep-onset latency (3.0 ± 1.2 min, p = 0.013), and increased respiration rate in non-REM sleep (0.32 ± 0.08 respirations per min, p = <0.001), compared to the night before the game. The present findings show that deep and REM sleep and respiration rate in non-REM sleep are the key indicators of perceived fatigue in female elite soccer players. Moreover, sleep is disrupted during game night, likely due to the high physical and mental loads experienced during soccer games. Sleep normalizes during the first and second night after soccer games, likely preventing further negative performance-related consequences.

Effects of Exercise Mode on Postprandial Metabolism in Humans with Chronic Paraplegia

PURPOSE

The purpose of this study was to assess the acute effects of exercise mode and intensity on postprandial macronutrient metabolism.

METHODS

Ten healthy men age 39 ± 10 yr with chronic paraplegia (13.2 ± 8.8 yr, ASIA A-C) completed three isocaloric bouts of upper-body exercise and a resting control. After an overnight fast, participants completed circuit resistance exercise (CRE) first and the following conditions in a randomized order, separated by >48 h: i) control (CON), ~45-min seated rest; ii) moderate-intensity continuous exercise (MICE), ~40-min arm cranking at a resistance equivalent to ~30% peak power output (PPO); and iii) high-intensity interval exercise (HIIE), ~30 min arm cranking with resistance alternating every 2 min between 10% PPO and 70% PPO. After each condition, participants completed a mixed-meal tolerance test consisting of a 2510-kJ liquid meal (35% fat, 50% carbohydrate, 15% protein). Blood and expired gas samples were collected at baseline and regular intervals for 150 min after a meal.

RESULTS

An interaction (P < 0.001) was observed, with rates of lipid oxidation elevated above CON in HIIE until 60 min after a meal and in CRE at all postprandial time points up to 150 min after a meal. Postprandial blood glycerol was greater in MICE (P = 0.020) and CRE (P = 0.001) compared with CON. Furthermore, nonesterified fatty acid area under the curve had a moderate-to-strong effect in CRE versus MICE and HIIE (Cohen's d = -0.76 and -0.50, respectively).

CONCLUSIONS

In persons with paraplegia, high-intensity exercise increased postprandial energy expenditure independent of the energy cost of exercise. Furthermore, exercise combining resistance and endurance modes (CRE) showed the greater effect on postprandial lipid oxidation.

Innate antiviral defense demonstrates high energetic efficiency in a bony fish

Background

Viruses can impose energetic demands on organisms they infect, in part by hosts mounting resistance. Recognizing that oxygen uptake reliably indicates steady-state energy consumption in all vertebrates, we comprehensively evaluated oxygen uptake and select transcriptomic messaging in sockeye salmon challenged with either a virulent rhabdovirus (IHNV) or a low-virulent reovirus (PRV). We tested three hypotheses relating to the energetic costs of viral resistance and tolerance in this vertebrate system: (1) mounting resistance incurs a metabolic cost or limitation, (2) induction of the innate antiviral interferon system compromises homeostasis, and (3) antiviral defenses are weakened by acute stress.

Results

IHNV infections either produced mortality within 1–4 weeks or the survivors cleared infections within 1–9 weeks. Transcription of three interferon-stimulated genes (ISGs) was strongly correlated with IHNV load but not respiratory performance. Instead, early IHNV resistance was associated with a mean 19% (95% CI = 7–31%; p = 0.003) reduction in standard metabolic rate. The stress of exhaustive exercise did not increase IHNV transcript loads, but elevated host inflammatory transcriptional signaling up to sevenfold. For PRV, sockeye tolerated high-load systemic PRV blood infections. ISG transcription was transiently induced at peak PRV loads without associated morbidity, microscopic lesions, or major changes in aerobic or anaerobic respiratory performance, but some individuals with high-load blood infections experienced a transient, minor reduction in hemoglobin concentration and increased duration of excess post-exercise oxygen consumption.

Conclusions

Contrary to our first hypothesis, effective resistance against life-threatening rhabdovirus infections or tolerance to high-load reovirus infections incurred minimal metabolic costs to salmon. Even robust systemic activation of the interferon system did not levy an allostatic load sufficient to compromise host homeostasis or respiratory performance, rejecting our second hypothesis that this ancient innate vertebrate antiviral defense is itself energetically expensive. Lastly, an acute stress experienced during testing did not weaken host antiviral defenses sufficiently to promote viral replication; however, a possibility for disease intensification contingent upon underlying inflammation was indicated. These data cumulatively demonstrate that fundamental innate vertebrate defense strategies against potentially life-threatening viral exposure impose limited putative costs on concurrent aerobic or energetic demands of the organism.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-021-01069-2.

Oxyhemoglobin Concentration and Oxygen Uptake Signal During Recovery From Exhaustive Exercise in Healthy Subjects-Relationship With Aerobic Capacity

This proof of concept study is dedicated to the quantification of the short-term recovery phase of the muscle oxygenation and whole-body oxygen uptake kinetics following an exhaustive cycling protocol. Data of 15 healthy young participants (age 26.1 ± 2.8 years, peak oxygen uptake 54.1 ± 5.1 mL^∗min-1^∗kg-1) were recorded during 5 min cool down-cycling with a power output of 50 W on an electro-magnetically braked cycle ergometer. The oxygen uptake (VO₂) signal during recovery was modeled by exponential function. Using the model parameters, the time (T_1/2) needed to return VO₂ to 50% of VO_2peak was determined. The Hill’s model was used to analyze the kinetics of oxyhemoglobin concentration (Sm, %), non-invasively recorded by near-infrared spectroscopy (NIRS) over the M. vastus lateralis. Analysis of the Pearson correlation results in statistically significant negative relationships between T_1/2 and relative VO_2peak (r = −0.7). Relevant significant correlations were determined between constant defining the slope of VO₂ decrease (parameter B) and the duration of the anaerobic phase (r = −0.59), as well as between Hill’s coefficient and average median Sm_max for the final 2 min of recovery. The high correlation between traditional variables commonly used to represent the cardio-metabolic capacity and the parameters of fits from exponential and Hill models attests the validity of our approach. Thus, proposed descriptors, derived from non-invasive NIRS monitoring during recovery, seem to reflect aerobic capacity. However, the practical usefulness of such modeling for clinical or other vulnerable populations has to be explored in studies using alternative testing protocols.

An overview of cycling as active transportation and as benefit for health

Active transportation is defined as travelling on foot, by bicycle or other non-motorized means, sometimes in combination with other forms of public transportation, in contrast with the use of motor vehicles. The prevalence of sedentary lifestyle and physical inactivity is a growing epidemic in most developed countries that spread over the last three decades; active transportation may be a promising approach to increase physical activity and reduce the risk of non-communicable diseases improving cardiorespiratory fitness and cardiometabolic health. The health benefits of physical activity in reducing mortality and morbidity have been proved by several publications. Cardiorespiratory fitness can be improved by regular physical activity with an amelioration of insulin sensitivity, blood lipid profile, body composition, inflammation, and blood pressure. Active transportation as a daily physical activity is less expensive compared to motor vehicle use. The advantages are remarkable in terms of contrasting obesity and sedentary lifestyle, decrease motor traffic congestion and mitigate climate change. Massive investments in policies and interventions aimed to increase active transportation are not generally promoted and there are differences in the prevalence of active transportation in the daily routine among different areas. As in the literature several studies as randomized trials or observational studies have been published, with different end-points, in order to investigate if active commuting may be the right answer to improve cardiorespiratory fitness and cardiometabolic health, we aimed to review the available evidences of cycling as an active transportation and to consider its benefits on health.

The effects of breaking sedentary time with different intensity exercise bouts on energy metabolism: A randomized cross-over controlled trial

BACKGROUND AND AIMS

Breaking up sedentary periods, particularly with light activity, increases total energy expenditure (EE), and helps provide better glycemic control. However, the effects of activities of various intensities to interrupt prolonged sedentary time are unclear. The purpose of the present study was to examine potential differences in glycemic control and EE from breaking up sedentary time with short exercise bouts of different intensities.

METHODS AND RESULTS

Nine overweight/obesity young men underwent whole body indirect calorimetry at 19:00 on day 1 and stayed overnight. After awakening on day 2, they performed short duration jogging every 30 min over 8 h (16-time bouts in total) under 3 different conditions with the same running distance: (1) lactate threshold (LT) for 2 min, (2) 60% LT for 200 s, and (3) onset of blood lactate accumulation (OBLA) for 75 s. The 24-h EE and interstitial glucose concentration (from 8:00 to 19:00 on day 2) was continuously measured throughout the trials. The standard deviation during intervention and indexes of postprandial of the interstitial glucose concentration was significantly lower at LT and OBLA than at 60% LT (p < 0.05). The 24-h EE was not significantly different among conditions, but EE at OBLA during intervention was slightly but significantly higher than at 60% LT and LT.

CONCLUSION

Breaking up sedentary time with short-duration jogging at LT and with OBLA intensities may have better glycemic control and increased use of carbohydrate as a fuel, while short-duration a jogging at OBLA intensity may increase EE.

TRIAL REGISTRATION

UMIN000041361.

W' Reconstitution Accelerates More with Decreasing Intensity in the Heavy- versus the Moderate-Intensity Domain

INTRODUCTION

The purpose of this study was to investigate the effect of the recovery intensity domain on W' reconstitution. We used the W'BAL model as a framework and tested its predictive capabilities (W'PRED) across the different intensity domains.

METHODS

Twelve young men (51.7 ± 5.9 mL·kg-1·min-1) completed a ramp incremental test, three to five constant power output (PO) tests to determine critical power (CP) and W', and minimally two trials to verify the maximal lactate (La-) steady state. During four experimental trials, subjects performed two work bouts (WB1 and WB2) at P6 (i.e., PO that predicts exhaustion within 6 min) separated by a recovery interval at CP-10 W, Δgas exchange threshold (GET)-CP, GET, and 50% GET, respectively. WB1 was designed to deplete 75% W', and the recovery time varied to replenish 50% W'. WB2 was performed to exhaustion (W'ACT). W'PRED was compared with W'ACT to evaluate the accuracy of the W'BAL model. Excess postexercise oxygen consumption was calculated as the difference between the measured and the predicted oxygen uptake during recovery.

RESULTS

W'ACT averaged 49% ± 24%, 69% ± 24%, 81% ± 28%, and 93% ± 21% for CP-10 W, ΔGET-CP, GET, and 50% GET, respectively (P = 0.002). W'PRED overestimated W'ACT in CP-10 W (34% ± 32%, P = 0.004) and underestimated W'ACT in 50% GET (24% ± 28%, P = 0.013). Excess postexercise oxygen consumption was lowest in CP-10 W (P < 0.01) and higher in GET compared with ΔGET-CP (P = 0.01).

CONCLUSION

We demonstrated that W'PRED overestimated and underestimated W'ACT in the heavy- and moderate-intensity domain, respectively. Therefore, the practical applicability of a single recovery time constant, which only relies on the difference between the recovery PO and the CP, is questionable.

The Effects of Powered Exoskeleton Gait Training on Cardiovascular Function and Gait Performance: A Systematic Review

Patients with neurological impairments often experience physical deconditioning, resulting in reduced fitness and health. Powered exoskeleton training may be a successful method to combat physical deconditioning and its comorbidities, providing patients with a valuable and novel experience. This systematic review aimed to conduct a search of relevant literature, to examine the effects of powered exoskeleton training on cardiovascular function and gait performance. Two electronic database searches were performed (2 April 2020 to 12 February 2021) and manual reference list searches of relevant manuscripts were completed. Studies meeting the inclusion criteria were systematically reviewed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. n = 63 relevant titles were highlighed; two further titles were identified through manual reference list searches. Following analysis n = 23 studies were included. Data extraction details included; sample size, age, gender, injury, the exoskeleton used, intervention duration, weekly sessions, total sessions, session duration and outcome measures. Results indicated that exoskeleton gait training elevated energy expenditure greater than wheelchair propulsion and improved gait function. Patients exercised at a moderate-intensity. Powered exoskeletons may increase energy expenditure to a similar level as non-exoskeleton walking, which may improve cardiovascular function more effectively than wheelchair propulsion alone.

Metabolic Profile of Reciprocal Supersets in Young, Recreationally Active Women and Men

ABSTRACT

Realzola, RA, Mang, ZA, Millender, DJ, Beam, JR, Bellovary, BN, Wells, AD, Houck, JM, and Kravitz, L. Metabolic profile of reciprocal supersets in young, recreationally active females and males. J Strength Cond Res XX(X): 000-000, 2020-Reciprocal supersets (RSSs) are a time-efficient style of resistance exercise (RE) that consist of performing 2 consecutive exercises with opposing muscle groups while limiting rest times between them. Previous research in men indicates a RSS has an increased physiological response when compared with traditional RE (TRAD). No between-sex comparison of metabolic data for RSSs exists. The purpose of this study was to create a metabolic profile for RSSs in men and women. Eighteen resistance-trained individuals underwent 2 bouts of volume-load equated RE: RSS and TRAD. Reciprocal superset exercises were split into 3 clusters: (a) hexagonal bar deadlift superset with leg press, (b) chest press superset with seated row, and (c) overhead dumbbell press superset with latissimus dorsi pull-downs. The TRAD protocol, doing the same exercises, emulated hypertrophy emphasis training. Oxygen uptake (V[Combining Dot Above]O2), heart rate (HR), blood lactate ([BLa]), rate of perceived exertion (RPE), and excess post-exercise oxygen consumption (EPOC) were measured. Aerobic and anaerobic energy expenditure were estimated using V[Combining Dot Above]O2 and lactate, respectively. The level of significance set for this study was p ≤ 0.05. Regardless of sex, a RSS elicited significantly greater average V[Combining Dot Above]O2, HR, [BLa], RPE, and anaerobic and aerobic energy expenditures, and was completed in a shorter time compared with TRAD (p ≤ 0.05). When compared with women, men had significantly greater EPOC, average [BLa], and anaerobic and aerobic energy expenditures during RSSs (p ≤ 0.05). The average [BLa] and aerobic energy expenditure of the men were also significantly greater than the women during TRAD (p ≤ 0.05). This study suggests that a RSS is a metabolically demanding RE session that may elicit increases in musculoskeletal, cardiorespiratory, and physiological adaptations while decreasing the duration of exercise.

Estimation of Metabolic Energy Expenditure during Short Walking Bouts

Assessment of metabolic energy expenditure from indirect calorimetry is currently limited to sustained (>4 min) cyclic activities, because of steady-state requirements. This is problematic for patient populations who are unable to perform such sustained activities. Therefore, this study explores validity and reliability of a method estimating metabolic energy expenditure based on oxygen consumption (V̇O₂) during short walking bouts. Twelve able-bodied adults twice performed six treadmill walking trials (1, 2 and 6 min at 4 and 5 km/h), while V̇O₂ was measured. Total V̇O₂ was calculated by integrating net V̇O₂ over walking and recovery. Concurrent validity with steady-state V̇O₂ was assessed with Pearson's correlations. Test-retest reliability was assessed using intra-class correlation coefficients (ICC) and Bland-Altman analyses. Total V̇O₂ was strongly correlated with steady-state V̇O₂ (r=0.91-0.99), but consistently higher. Test-retest reliability of total V̇O₂ (ICC=0.65-0.92) was lower than or comparable to steady-state V̇O₂ (ICC=0.83-0.92), with lower reliability for shorter trials. Total V̇O₂ discriminated between gait speeds. Total oxygen uptake provides a useful measure to estimate metabolic load of short activities from oxygen consumption. Although estimates are less reliable than steady-state measurements, they can provide insight in the yet unknown metabolic demands of daily activities for patient populations unable to perform sustained activities.

High-Intensity Interval vs. Continuous Endurance Training: Preventive Effects on Hormonal Changes and Physiological Adaptations in Prediabetes Patients

ABSTRACT

Safarimosavi, S, Mohebbi, H, and Rohani, H. High-intensity interval vs. continuous endurance training: Preventive effects on hormonal changes and physiological adaptations in prediabetes patients. J Strength Cond Res 35(3): 731-738, 2021-The aim of this study was to examine the effects of a 12-week high-intensity interval training (HIIT) intervention, or an isocaloric continuous endurance training (CET) intervention on insulin resistance indices and change in irisin and preptin in patients with prediabetes. Thirty-two prediabetic male patients (age = 38.7 ± 4; body mass index = 26.9 ± 1.4 kg·m-2; and V̇o2peak = 2.49 ± 0.22 L·min-1) were randomly assigned into 3 training groups (N = 8). These groups were matched based on the required energy expenditure (EE) for completing each protocol: (a) HIIT (10 × 60 seconds at 90% peak oxygen uptake [V̇o2peak], 1: 1 work to recovery at 50 W), (b) CET at an intensity equivalent to maximal fat oxidation (Fatmax) (CETFAT) (pedaling for a duration that expends an equivalent EE to an HIIT session [E ≈ HIIT]), (c) CET at an intensity equivalent to anaerobic threshold (CETAT) (E ≈ HIIT), and (d) the control group (CON): continued to perform their daily activities. After intervention, blood glucose levels were significantly (p < 0.05) lower in the HIIT group compared with CETAT group. Exercise training improved the insulin resistance index by 35, 28, and 37% in CETFAT, CETAT, and HIIT groups, respectively. Irisin concentrations in the HIIT and CETAT groups was significantly (p < 0.05) decreased compared with the pre-training values. Also, HIIT and CETFAT resulted in significant (p < 0.05) changes in preptin concentration compared with baseline. This study demonstrated that both HIIT and CETFAT protocols had similar effects on the insulin resistance index of prediabetic patients. Also, the intensity and type of exercise were effective factors in changing irisin and preptin concentrations.

Estimating excess post-exercise oxygen consumption using multiple linear regression in healthy Korean adults: a pilot study

Purpose

This pilot study aimed to develop a regression model to estimate the excess post-exercise oxygen consumption (EPOC) of Korean adults using various easy-to-measure dependent variables.

Methods

The EPOC and dependent variables for its estimation (e.g., sex, age, height, weight, body mass index, fat-free mass [FFM], fat mass, % body fat, and heart rate_sum [HR_sum]) were measured in 75 healthy adults ( 31 males, 44 females). Statistical analysis was performed to develop an EPOC estimation regression model using the stepwise regression method.

Results

We confirmed that FFM and HR_sum were important variables in the EPOC regression models of various exercise types. The explanatory power and standard errors of estimates (SEE) for EPOC of each exercise type were as follows: the continuous exercise (CEx) regression model was 86.3% (R2) and 85.9% (adjusted R2), and the mean SEE was 11.73 kcal, interval exercise (IEx) regression model was 83.1% (R2) and 82.6% (adjusted R2), while the mean SEE was 13.68 kcal, and the accumulation of short-duration exercise (AEx) regression models was 91.3% (R2) and 91.0% (adjusted R2), while the mean SEE was 27.71 kcal. There was no significant difference between the measured EPOC using a metabolic gas analyzer and the predicted EPOC for each exercise type.

Conclusion

This pilot study developed a regression model to estimate EPOC in healthy Korean adults. The regression model was as follows: CEx = -37.128 + 1.003 × (FFM) + 0.016 × (HR_sum), IEx = -49.265 + 1.442 × (FFM) + 0.013 × (HR_sum), and AEx = -100.942 + 2.209 × (FFM) + 0.020 × (HR_sum).

Substrate metabolism during recovery from circuit resistance exercise in persons with spinal cord injury

INTRODUCTION

Whole body energy expenditure and lipid oxidation (Lox) are upregulated during and after exercise. Persons with spinal cord injury (SCI) generally have a blunted ability to utilize fat during exercise, but it is unknown if their substrate partitioning is affected during recovery from exercise.

PURPOSE

To determine the effect of a single session of upper body circuit resistance exercise (CRE) on energy expenditure and Lox during exercise recovery in persons with and without SCI.

METHODS

Twenty four persons (3 groups; 7 male and 1 female per group) without paralysis (neurologically intact; N) or with chronic (≥ 1 yr) paraplegia (P) or tetraplegia (T) participated. Energy expenditure and substrate partitioning were assessed via indirect calorimetry before, during, and three times after (up to 120 min after) a single session of CRE, or time-matched seated control (CON).

RESULTS

During CRE, all groups experienced a similar relative increase in oxygen consumption (49 ± 13, 55 ± 11, and 48 ± 15% VO_2peak for N, P, and T, respectively). The Post_0-120 energy expenditure was greater following CRE vs. CON (P < 0.01) and independent of injury characteristics (10.6, 22.6, and 14.3% higher than CON for N, P, and T; P = 0.21). The absolute increase in Lox above CON during recovery was similar for N, P, and T (5.74 ± 2.81, 6.62 ± 3.10, and 4.50 ± 3.91 g, respectively; P = 0.45).

CONCLUSIONS

Energy expenditure and lipid utilization was increased similarly following circuit exercise in persons without and with spinal cord injury in a manner independent of level of injury.

Rapid component of excess post-exercise oxygen consumption of children of different weight status after playing active video games

BACKGROUND

Excess post-exercise oxygen consumption (EPOC) of children could indicate the potential of an exercise therapy to treat or prevent obesity. However, EPOC as a result of playing active video games (AVG) has been poorly investigated. Therefore, we aimed to investigate the rapid component of EPOC of children with healthy weight and overweight/obesity (according to their BMI percentile) after playing AVGs that feature predominately upper body (UB) and whole-body (WB) movement.

METHODS

Twenty-one children with healthy weight (BMI percentile < 85%) and with overweight/obesity (BMI percentile ≥ 85%) randomly underwent two 10-min AVG sessions (UB and WB). The heart rate (HR), minute ventilation (VE), oxygen consumption (VO2) and carbon dioxide production (VCO2) were recorded during exercise and post-exercise recovery period. For the rapid component of EPOC in each AVG session, measurements were recorded every 15 s for 5-min of post-exercise recovery. The rate of perceived exertion (RPE) was also measured immediately before and after each AVG play.

RESULTS

Children with overweight/obesity had a higher average of absolute VE, VO2, and VCO2 than their healthy-weight counterparts (BMI percentile < 85%; n = 21) during post-exercise recovery. RPE, HR, and HR% were not different between the game sessions and weight groups. Children with overweight/obesity showed a higher absolute VO2 during EPOC than healthy-weight children in both game sessions, but relative VO2 was higher in healthy-weight children during EPOC. No differences were observed for EPOC between UB and WB sessions.

CONCLUSIONS

Children with overweight/obesity had a greater EPOC than healthy-weight children after AVG sessions in terms of absolute oxygen values, whereas healthy-weight children have higher EPOC considering relative VO2 when controlling for body mass. UB and WB AVGs induced a similar EPOC among children with healthy weight and overweight/obesity. As UB and WB AVGs induce the rapid component of EPOC in children regardless their weight status, AVGs could be used as an exercise method to treat and prevent child obesity.

Order of concentric and eccentric muscle actions affects metabolic responses

BACKGROUND

Resistance exercise provides an effective stimulus for improving the metabolic plasticity of skeletal muscle, and the type of acute muscle contraction plays an important role in determining specific responses and adaptations. The purpose of the current investigation was to examine the effect of contraction order on metabolic responses by comparing monophasic concentric and eccentric squats versus a protocol incorporating alternated concentric and eccentric repetitions.

METHODS

Twelve recreationally active men (21.1±1.1yr) performed three nearly identical squat protocols on separate days. Protocols varied only with contraction-type, including 4 sets × 10 reps concentric-only (CON), eccentric-only (ECC), and BOTH which alternated 5 concentric followed by 5 eccentric reps (CON-ECC; sets 1 and 3) and vice versa (ECC-CON; sets 2 and 4). The experimental trials were performed once weekly in a randomized, counter-balanced order, and expired gases were collected using a two-way non-rebreathing mask and oxygen consumption quantified with indirect calorimetry. Subjects raised (CON) and lowered (ECC) the load in 2s, and all sets (2 min) and repetitions (8 s) were separated by standardized rest intervals.

RESULTS

From the BOTH protocol, the increase in metabolic rate was significantly greater (P≤0.05) during squats performed with CON-ECC order (0.60±0.11 L·min^-1) compared to ECC-CON (0.44±0.07 L·min^-1), but excess postexercise oxygen consumption (EPOC) was opposite, with significantly greater metabolic rate during the 2-minute rest intervals after ECC-CON squats (0.46±0.09 L·min^-1) compared to CON-ECC (0.25±0.05 L·min^-1). Metabolic rates during and after squats were significantly greater (P≤0.05) with CON (0.63±0.09; 0.49±0.10 L·min-1) compared to ECC (0.34±0.04; 0.20±0.04 L·min-1), respectively.

CONCLUSIONS

These data present an interesting paradigm regarding the contraction-dependent metabolic responses to monophasic resistance exercise and suggest a greater EPOC following concentric versus eccentric muscle actions.

Physiological Exercise and Post-Exercise Effects of Inverse Sequences of Combined Bench-Step Aerobics and Resistance Exercise

The purpose of this study was to compare the effects of using inverse sequences of combined bench-step aerobics and resistance exercise on cardiorespiratory, hemodynamic and perceptual variables during exercise and one-hour post-exercise. The tested sequences were bench-step aerobics immediately before and immediately after resistance exercise. Thirteen apparently healthy and physically active women (age = 21.9 ± 6.1 years, body height = 160 ± 0.1 cm, body mass = 58.8 ± 7.5 kg, estimated fat mass = 17.2 ± 2.0% and estimated maximal oxygen uptake = 37.5 ± 2.6 mL∙kg-1∙min-1) performed a 20-minute bench-step aerobics routine, immediately before (STEP_RES) and after (RES_STEP) resistance exercise. Oxygen uptake and heart rate were continuously measured, systolic and diastolic blood pressure, body temperature and perceived exertion were measured at rest, immediately after each type of exercise and at 15, 30, 45 and 60 min after exercise. When resistance exercise was performed first (RES_STEP), oxygen uptake was higher (23.2 ± 3.9 vs. 20.5 ± 4.8 mL∙kg-1∙min-1), but the heart rate (164.5 ± 9.1 vs. 173.9 ± 11.7 bpm) and body temperature (36.5 ± 0.4 vs. 37.6 ± 0.6 ºC) were lower. In both sequences, the type of exercise performed first was pointed out with a lower perceived exertion or lower perceived intensity. Exercise and 60-min post-exercise blood pressure had a similar response in both sequences, and systolic blood pressure along with diastolic blood pressure were lower than pre-exercise from 30 min until 60 min post-exercise. The results suggest that the sequence affected oxygen uptake and perceived exertion during exercise and that this total workload, despite the sequence, promoted a post-exercise blood pressure decrease in normotensive participants.

Exercise Interventions Targeting Obesity in Persons With Spinal Cord Injury

Spinal cord injury (SCI) results in an array of cardiometabolic complications, with obesity being the most common component risk of cardiometabolic disease (CMD) in this population. Recent Consortium for Spinal Cord Medicine Clinical Practice Guidelines for CMD in SCI recommend physical exercise as a primary treatment strategy for the management of CMD in SCI. However, the high prevalence of obesity in SCI and the pleiotropic nature of this body habitus warrant strategies for tailoring exercise to specifically target obesity. In general, exercise for obesity management should aim primarily to induce a negative energy balance and secondarily to increase the use of fat as a fuel source. In persons with SCI, reductions in the muscle mass that can be recruited during activity limit the capacity for exercise to induce a calorie deficit. Furthermore, the available musculature exhibits a decreased oxidative capacity, limiting the utilization of fat during exercise. These constraints must be considered when designing exercise interventions for obesity management in SCI. Certain forms of exercise have a greater therapeutic potential in this population partly due to impacts on metabolism during recovery from exercise and at rest. In this article, we propose that exercise for obesity in SCI should target large muscle groups and aim to induce hypertrophy to increase total energy expenditure response to training. Furthermore, although carbohydrate reliance will be high during activity, certain forms of exercise might induce meaningful postexercise shifts in the use of fat as a fuel. General activity in this population is important for many components of health, but low energy cost of daily activities and limitations in upper body volitional exercise mean that exercise interventions targeting utilization and hypertrophy of large muscle groups will likely be required for obesity management.

Strength Training Reduces Fat Accumulation and Improves Blood Lipid Profile Even in the Absence of Skeletal Muscle Hypertrophy in High-Fat Diet-Induced Obese Condition

The aim was to investigate the effect of strength training on skeletal muscle morphology and metabolic adaptations in obese rats fed with unsaturated high-fat diet (HFD). The hypothesis was that strength training induces positive metabolic adaptations in obese rats despite impaired muscle hypertrophy. Male Wistar rats (n = 58) were randomized into two groups and fed a standard diet or a high-fat diet (HFD) containing 49.2% of fat. After induction and maintenance to obesity, the rats were divided into four groups: animals distributed in sedentary control (CS), control submitted to strength training protocol (CT), obese sedentary (ObS), and obese submitted to strength training protocol (ObT). The exercise protocol consisted of 10 weeks of training on a vertical ladder (three times a week) with a load attached to the animal’s tail. At the end of 10 weeks, strength training promoted positive changes in the body composition and metabolic parameters in obese animals. Specifically, ObT animals presented a reduction of 22.6% and 14.3% in body fat and adiposity index when compared to ObS, respectively. Furthermore, these rats had lower levels of triglycerides (ObT = 23.1 ± 9.5 vs. ObS = 30.4 ± 6.9 mg/dL) and leptin (ObT = 13.2 ± 7.2 vs. ObS = 20.5 ± 4.3 ng/mL). Training (ObT and CT) induced a greater strength gain when compared with the respective control groups. In addition, the weight of the flexor hallucis longus (FHL) muscle was higher in the ObT group than in the CT group, representing an increase of 26.1%. However, training did not promote hypertrophy as observed by a similar cross-sectional area of the FHL and plantar muscles. Based on these results, high-intensity strength training promoted an improvement of body composition and metabolic profile in obese rats that were fed a high-fat diet without skeletal muscle adaptations, becoming a relevant complementary strategy for the treatment of obesity.

Underlying mechanisms of oxygen uptake kinetics in chronic post-stroke individuals: A correlational, cross-sectional pilot study

Post-stroke individuals presented deleterious changes in skeletal muscle and in the cardiovascular system, which are related to reduced oxygen uptake ([Formula: see text]) and take longer to produce energy from oxygen-dependent sources at the onset of exercise (mean response time, MTRON) and during post-exercise recovery (MRTOFF). However, to the best of our knowledge, no previous study has investigated the potential mechanisms related to [Formula: see text] kinetics response (MRTON and MRTOFF) in post-stroke populations. The main objective of this study was to determine whether the MTRON and MRTOFF are related to: 1) body composition; 2) arterial compliance; 3) endothelial function; and 4) hematological and inflammatory profiles in chronic post-stroke individuals. Data on oxygen uptake ([Formula: see text]) were collected using a portable metabolic system (Oxycon Mobile®) during the six-minute walk test (6MWT). The time to achieve 63% of [Formula: see text] during a steady state (MTRON) and recovery (MRTOFF) were analyzed by the monoexponential model and corrected by a work rate (wMRTON and wMRTOFF) during 6MWT. Correlation analyses were made using Spearman's rank correlation coefficient (rs) and the bias-corrected and accelerated bootstrap method was used to estimate the 95% confidence intervals. Twenty-four post-stroke participants who were physically inactive took part in the study. The wMRTOFF was correlated with the following: skeletal muscle mass (rs = -0.46), skeletal muscle mass index (rs = -0.45), augmentation index (rs = 0.44), augmentation index normalized to a heart rate of 75 bpm (rs = 0.64), reflection magnitude (rs = 0.43), erythrocyte (rs = -0.61), hemoglobin (rs = -0.54), hematocrit (rs = -0.52) and high-sensitivity C-reactive protein (rs = 0.58), all p < 0.05. A greater amount of oxygen uptake during post-walking recovery is partially related to lower skeletal muscle mass, greater arterial stiffness, reduced number of erythrocytes and higher systemic inflammation in post-stroke individuals.

The Relationship Between Repeated-Sprint Ability, Aerobic Capacity, and Oxygen Uptake Recovery Kinetics in Female Soccer Athletes

This study investigated the relationship between repeated-sprint ability, aerobic capacity, and oxygen uptake kinetics during the transition between exercise and recovery (off-transient) in female athletes of an intermittent sport modality. Eighteen professional soccer players completed three tests: 1) a maximal incremental exercise test; 2) a constant speed time-to-exhaustion test; and 3) a repeated-sprint ability test consisting of six 40-m sprints with 20 s of passive recovery in-between. Correlations between time-to-exhaustion, repeated-sprint ability, and oxygen uptake kinetics were calculated afterwards. The level of significance was set at p < 0.05. A performance decrement during repeated-sprint ability was found to be related to: 1) time-to-exhaustion (e.g., exercise tolerance; r = -0.773, p < 0.001); 2) oxygen uptake recovery time (r = 0.601, p = 0.008); and 3) oxygen uptake mean response time of recovery (r = 0.722, p < 0.001). Moreover, the best sprint time (r = -0.601, p = 0.008) and the mean sprint time (r = -0.608, p = 0.007) were found to be related to maximal oxygen uptake. Collectively, these results reinforce the relation between oxygen uptake kinetics and the ability to maintain sprint performance in female athletes. These results may contribute to coaches and training staff of female soccer teams to focus on training and improve their athletes’ aerobic capacity and recovery capacity to improve intermittent exercise performance.

Metabolic reduction after long-duration flight is not related to fat-free mass loss or flight duration in a migratory passerine

Migratory birds catabolize large quantities of protein during long flights, resulting in dramatic reductions in organ and muscle mass. One of the many hypotheses to explain this phenomenon is that decrease in lean mass is associated with reduced resting metabolism, saving energy after flight during refueling. However, the relationship between lean body mass and resting metabolic rate remains unclear. Furthermore, the coupling of lean mass with resting metabolic rate and with peak metabolic rate before and after long-duration flight have not previously been explored. We flew migratory yellow-rumped warblers (Setophaga coronata) in a wind tunnel under one of two humidity regimes to manipulate the rate of lean mass loss in flight, decoupling flight duration from total lean mass loss. Before and after long-duration flights, we measured resting and peak metabolism, and also measured fat mass and lean body mass using quantitative magnetic resonance. Flight duration ranged from 28 min to 600 min, and birds flying under dehydrating conditions lost more fat-free mass than those flying under humid conditions. After flight, there was a 14% reduction in resting metabolism but no change in peak metabolism. Interestingly, the reduction in resting metabolism was unrelated to flight duration or to change in fat-free body mass, indicating that protein metabolism in flight is unlikely to have evolved as an energy-saving measure to aid stopover refueling, but metabolic reduction itself is likely to be beneficial to migratory birds arriving in novel habitats.

DOES THE NUMBER OF JOINTS INVOLVED IN EXERCISE PROMOTE CHANGES IN ENERGY EXPENDITURE?

ABSTRACT Introduction: The benefits of strength training (ST) include not only strength improvement but also favorable body composition changes, which has led to a considerable increase in the indication of this training method in overweight and obese individuals, and has made the investigation of outcomes attributed to different manipulations of ST variables an important task. However, acute metabolic responses related to energy expenditure (EE) associated with the manipulation of exercises which, in turn, are associated with the number of joints involved in movement, are still inconclusive. Objective: To verify the influence of the number of joints involved in movement on EE with equalized volume in ST at different intensities. Methods: This training program was held on alternate days, with a 48-hour interval between each session, and with two randomized protocols, as follows: multi joint protocol with four common exercises for ST participants compared to the single joint protocol with four exercises. Each protocol was evaluated at three training intensities (90%, 75% and 60% of 1-RM) according to the one-repetition maximum test. Results: Significant increases in EE were observed in the multi joint session as compared to the single joint session: 90% 1-RM multi joint 246.80 ± 26.17 kcal vs single joint 227.40 ± 24.54 kcal (∆ -7.86, 95% CI 7.33; 31.46; t 3.44; p <0.05); 75% 1-RM multi joint 124.13 ± 25.40 kcal vs single joint 111.80 ± 22.78 kcal (∆ -9.93, 95% CI 3.25; 21.41; t 2.91; p <0.05); 60% 1-RM multi joint 70.80 ± 6.28 kcal vs single joint 64.40 ± 6.72 kcal (∆-9.04, 95% CI 3.95; 8.84; t 5.60; p <0.05). Conclusion: Multi joint exercises may be a variable to consider when EE balance is the main target of the ST program. However, further studies are needed to supplement our findings. Level of evidence II; Diagnostic studies-Investigating a diagnostic test.

Acute metabolic responses after continuous or interval exercise in post-menopausal women with overweight or obesity

This pilot study compared the effects of acute high-intensity intermittent exercise (HIIE) and moderate-intensity continuous exercise (MICE) on post-exercise VO₂ , fat utilization, and 24-hours energy balance to understand the mechanism of higher fat mass reduction observed after high-intensity interval training in post-menopausal women with overweight/obesity. 12 fasted women (59.5 ± 5.8 years; BMI: 28.9 ± 3.9 kg·m^-2 ) completed three isoenergetic cycling exercise sessions in a counterbalanced, randomized order: (a) MICE [35 minutes at 60%-65% of peak heart rate, HR_max ], (b) HIIE 1 [60 × (8-s cycling-12-s recovery) at 80%-90% of HR_max ], and (c) HIIE 2 [10 × 1min at 80%-90% of HR_max  - 1-min recovery]. Then, VO₂ and fat utilization measured at rest and during the 2 hours post-exercise, enjoyment, perceived exertion, and appetite recorded during the session and energy intake (EI) and energy expenditure (EE) assessed over the next 24 hours were compared for the three modalities. Overall, fat utilization increased after exercise. No modality effect or time-modality interaction was observed concerning VO₂ and fat oxidation rate during the 2 hours post-exercise. The two exercise modalities did not induce specific EI and EE adaptations, but perceived appetite scores at 1 hour post-exercise were lower after HIIE 1 and HIIE 2 than MICE. Perceived exertion was higher during HIIE 1 and HIIE 2 than MICE, but enjoyment did not differ among modalities. The acute HIIE responses did not allow explaining the greater fat mass loss observed after regular high-intensity interval training in post-menopausal women with overweight/obesity. More studies are needed to understand the mechanisms involved in such adaptations.

Does Oxygen Uptake Before Physical Exercise Affect Tear Osmolarity?

Recently, it has been reported that tear osmolarity (Tosm) is correlated with plasma osmolarity and will increase during exertion. We aimed to assess whether inhaling oxygen-enriched air between exercises could significantly change the Tosm value. Thirty men aged 24.9 years were included in the study. A cycloergometer was used to perform the exercise protocol. We recorded the participants’ Tosm (mOsm/L), heart rate (HR, beats/minute), oxygen saturation, and blood pressure values. After the first exhaustive exercise (T1), participants inhaled oxygen in the experimental group and a placebo in the control group. After the second exercise (T2), another set of measurements was obtained. The Tosm value before exercise was 297.4 ± 1.21 and 296.53 ± 1.11 mOsm/L (p = 0.61718) and the HR was 72.6 ± 2.59 and 73 ± 2.59 beats/minute (p = 0.39949) in the study and the control group, respectively. At T1, Tosm was 303.67 ± 1.25 and 302.2 ± 1.25 mOsm/L (p = 0.41286) and the HR reached 178.04 ± 2.60 and 176.4 ± 2.60 beats/minute (p = 0.65832), respectively. At T2, Tosm in the study group reached 305.73 ± 0.86 mOsm/L (correlation with the use of oxygen: r = −0.3818), and in the control group, it was 308.4 ± 0.86 mOsm/L (p = 0.0373), while the HR reached 172.20 ± 2.53 beats/minute in the study group and 178.2 ± 2.53 beats/minute in the control group (p = 0.057). It was concluded that inhaling oxygen before and after exercise could increase the rate of recovery after exhaustive exercise.

Comparison of the 6-Min Propulsion and Arm Crank Ergometer Tests to Assess Aerobic Fitness in Manual Wheelchair Users With a Spinal Cord Injury

OBJECTIVE

The 6-Min Manual Wheelchair Propulsion Test is proposed to easily and rapidly assess aerobic fitness among long-term (≥3 mos) manual wheelchair users with spinal cord injury. However, aerobic responses to this test have not been established. This study aimed (1) to characterize aerobic responses during the 6-Min Manual Wheelchair Propulsion Test, (2) to establish parallel reliability between the 6-Min Manual Wheelchair Propulsion Test and the Maximal Arm Crank Ergometer Test, and (3) to quantify the strength of association between the total distance traveled during the 6-Min Manual Wheelchair Propulsion Test and peak oxygen consumption.

DESIGN

Twenty manual wheelchair users with a spinal cord injury completed both tests. Aerobic parameters were measured before, during, and after the tests. Main outcome measures were peak oxygen consumption and total distance traveled.

RESULTS

Progressive cardiorespiratory responses, consistent with guidelines for exercise testing, were observed during both tests. Similar peak oxygen consumption values were obtained during both tests (6-Min Manual Wheelchair Propulsion Test: 20.2 ± 4.9 ml/kg·min; Maximal Arm Crank Ergometer Test: 20.4 ± 5.0 ml/kg·min), were highly correlated (r = 0.92, P < 0.001), and had a good agreement (mean absolute difference = 0.21, 95% confidence interval = -0.70 to 1.11, P = 0.639). The peak oxygen consumption and total distance traveled (mean = 636.6 ± 56.9 m) during the 6-Min Manual Wheelchair Propulsion Test were highly correlated (r = 0.74, P < 0.001).

CONCLUSIONS

The 6-Min Manual Wheelchair Propulsion Test induces progressive aerobic responses consistent with guidelines for exercise testing and can be used to efficiently estimate aerobic fitness in manual wheelchair users with a spinal cord injury.

TO CLAIM CME CREDITS

Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME OBJECTIVES: Upon completion of this article, the reader should be able to: (1) Explain how to administer the Six-Minute Manual Wheelchair Propulsion Test in long-term manual wheelchair users with a spinal cord injury; (2) Contrast how the workload is developed between the Six-Minute Manual Wheelchair Propulsion Test and the Maximal Arm Crank Ergometry Test and recognize how these differences may affect physiological responses; and (3) Explain why caution is advised regarding the use of the Six-Minute Manual Wheelchair Propulsion Test if aiming to estimate aerobic fitness.

LEVEL

Advanced ACCREDITATION: The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

Physiological responses to moderate intensity continuous and high-intensity interval exercise in persons with paraplegia

STUDY DESIGN

Randomized crossover.

OBJECTIVES

To test differences in the duration and magnitude of physiological response to isocaloric moderate intensity continuous (MICE) and high-intensity interval exercise (HIIE) sessions in persons with spinal cord injury (SCI).

SETTING

Academic medical center in Miami, FL, USA.

METHODS

Ten adult men (mean ± s.d.; 39 ± 10 year old) with chronic (13.2 ± 8.8 year) paraplegia (T2-T10) completed a graded exercise test. Then, in a randomized order, participants completed MICE and HIIE for a cost of 120 kcal. MICE was performed at 24.6% PO_peak. During HIIE, exercise was completed in 2 min work and recovery phases at 70%:10% PO_peak.

RESULTS

MICE and HIIE were isocaloric (115.9 ± 21.8 and 116.6 ± 35.0 kcal, respectively; p = 0.903), but differed in duration (39.8 ± 4.6 vs 32.2 ± 6.2 min; p < 0.001) and average respiratory exchange ratio (RER; 0.90 ± 0.08 vs 1.01 ± 0.07; p = 0.002). During MICE, a workrate of 24.6 ± 6.7% PO_peak elicited a V̇O₂ of 53.1 ± 6.5% V̇O_2peak (10.1 ± 2.2 ml kg^-1 min^-1). During HIIE, a workrate at 70% PO_peak elicited 88.3 ± 6.7% V̇O_2peak (16.9 ± 4.2 ml kg^-1 min^-1), and 29.4 ± 7.7% of the session was spent at or above 80% V̇O_2peak. During HIIE working phase, RER declined from the first to last interval (1.08 ± 0.07 vs 0.98 ± 0.09; p < 0.001), reflecting an initially high but declining glycolytic rate.

CONCLUSIONS

Compared with MICE, HIIE imposed a greater physiological stimulus while requiring less time to achieve a target caloric expenditure. Thus, exercise intensity might be an important consideration in the tailoring of exercise prescription to address the cardiometabolic comorbidities of SCI.

Effect of intensive prior exercise on muscle fiber activation, oxygen uptake kinetics, and oxygen uptake plateau occurrence

Purpose

We tested the hypothesis that the described increase in oxygen uptake (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2)-plateau incidence following a heavy-severe prior exercise is caused by a steeper increase in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2 and muscle fiber activation in the submaximal intensity domain.

Methods

Twenty-one male participants performed a standard ramp test, a \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{{\text{2max}}}}$$\end{document}V˙O2max verification bout, an unprimed ramp test with an individualized ramp slope and a primed ramp test with the same ramp slope, which was preceded by an intensive exercise at 50% of the difference between gas exchange threshold and maximum workload. Muscle fiber activation was recorded from vastus lateralis, vastus medialis, and gastrocnemius medialis using a surface electromyography (EMG) device in a subgroup of 11 participants. Linear regression analyses were used to calculate the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2-(\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta \dot{V}{\text{O}}_{{2}} /\Delta P$$\end{document}ΔV˙O2/ΔP) and EMG-(∆RMS/∆P) ramp test kinetics.

Results

Twenty out of the 21 participants confirmed their \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{{\text{2max}}}}$$\end{document}V˙O2max in the verification bout. The \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2-plateau incidence in these participants did not differ between the unprimed (n = 8) and primed (n = 7) ramp test (p = 0.500). The \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta \dot{V}{\text{O}}_{{2}} /\Delta P$$\end{document}ΔV˙O2/ΔP was lower in the primed compared to the unprimed ramp test (9.40 ± 0.66 vs. 10.31 ± 0.67 ml min⁻¹ W⁻¹, p < 0.001), whereas the ∆RMS/∆P did not differ between the ramp tests (0.62 ± 0.15 vs. 0.66 ± 0.14% W⁻¹; p = 0.744).

Conclusion

These findings do not support previous studies, which reported an increase in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2-plateau incidence as well as steeper increases in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2 and muscle fiber activation in the submaximal intensity domain following a heavy-severe prior exercise.

Whole-Body Metabolism, Carbohydrate Utilization, and Caloric Energy Balance After Sport Concussion: A Pilot Study

BACKGROUND

Sport concussion (SC) causes an energy crisis in the brain by increasing energy demand, decreasing energy supply, and altering metabolic resources. Whole-body resting metabolic rate (RMR) is elevated after more severe brain injuries, but RMR changes are unknown after SC. The purpose of this study was to longitudinally examine energy-related changes in collegiate athletes after SC.

HYPOTHESIS

RMR and energy consumption will increase acutely after SC and will return to control levels with recovery.

STUDY DESIGN

Case-control study.

LEVEL OF EVIDENCE

Level 4.

METHODS

A total of 20 collegiate athletes with SC (mean age, 19.3 ± 1.08 years; mean height, 1.77 ± 0.11 m; mean weight, 79.6 ± 23.37 kg; 55% female) were compared with 20 matched controls (mean age, 20.8 ± 2.17 years; mean height, 1.77 ± 0.10 m; mean weight, 81.9 ± 23.45 kg; 55% female). RMR, percentage carbohydrate use (%CHO), and energy balance (EBal; ratio between caloric consumption and expenditure) were assessed 3 times: T₁, ≤72 hours after SC; T₂, 7 days after T₁; and T_F, after symptom resolution. A 2 × 2 × 3 (group × sex × time) multivariate analysis of variance assessed RMR, %CHO, and EBal. Changes in RMR, %CHO, and EBal (T₁ to T_F) were correlated with days to symptom-free and days to return to play in the concussed group.

RESULTS

Women reported being symptom-free (median, 6 days; range, 3-10 days) sooner than men (median, 11 days; range, 7-16 days). RMR and %CHO did not differ across time between groups or for group × sex interaction. SC participants had higher EBal than controls at T₁ (P = 0.016) and T₂ (P = 0.010). In men with SC, increasing %CHO over time correlated with days to symptom-free (r = 0.735 and P = 0.038, respectively) and days to return to play (r = 0.829 and P = 0.021, respectively).

CONCLUSION

Participants with SC were in energy surplus acutely after injury. Although women recovered more quickly than men, men had carbohydrate metabolism changes that correlated with recovery time.

CLINICAL RELEVANCE

This pilot study shows that male and female student-athletes may have differing physiologic responses to SC and that there may be a role for dietary intervention to improve clinical outcomes after SC.

Similar Energy Expenditure During BodyPump and Heavy Load Resistance Exercise in Overweight Women

Purpose

High-repetition, low-load resistance exercise in group class settings has gained popularity in recent years, with BodyPump as a prime example. For individuals using exercise for body-weight management, the energy expenditure during exercise is of interest. Therefore, we herein aimed to estimate the energy expenditure during a session of BodyPump and a time-matched session of heavy load resistance training in overweight women (BMI ≥ 25.0).

Methods

Eighteen women participated in the study (mean age 35.4 years ± 10.2, BMI 30.4 kg/m² ± 4.8), 10 exercising BodyPump (50–100 repetitions each muscle group) and eight performed a heavy load session (eight repetition maximum × three sets). The energy expenditure was assessed with indirect calorimetry during the sessions and for two intervals at rest during the recovery phase: 0–20 and 120–140 min after the sessions.

Results

The BodyPump group lifted significantly more loads than the heavy load group (19,485 kg ± 2258 vs 15,616 kg ± 2976, p = 0.006), while energy expenditure was similar with 302 kcal ± 67 and 289 kcal ± 69 in BodyPump and heavy load group, respectively (p = 0.69). With no group differences, the resting metabolic rate (RMR) was elevated with 15–22% 2 h after exercise.

Conclusion

Overweight women achieved an energy expenditure of approximately 300 kcal (4.7 kcal per min) during a single session of BodyPump, which was similar with the women performing a single session of heavy load resistance exercise.

Relationship between maximal incremental and high-intensity interval exercise performance in elite athletes

This descriptive study aimed to explore the physiological factors that determine tolerance to exertion during high-intensity interval effort. Forty-seven young women (15–28 years old) were enrolled: 23 athletes from Taiwan national or national reserve teams and 24 moderately active females. Each participant underwent a maximal incremental INC (modified Bruce protocol) cardiopulmonary exercise test on the first day and high-intensity interval testing (HIIT) on the second day, both performed on a treadmill. The HIIT protocol involved alternation between 1-min effort at 120% of the maximal speed, at the same slope reached at the end of the INC, and 1-min rest until volitional exhaustion. Gas exchange, heart rate (HR), and muscle oxygenation at the right vastus lateralis, measured by near-infrared spectroscopy, were continuously recorded. The number of repetitions completed (R_lim) by each participant was considered the HIIT tolerance index. The results showed a large difference in the R_lim (range, 2.6–12.0 repetitions) among the participants. Stepwise linear regression revealed that the variance in the R_lim within the cohort was related to the recovery rates of oxygen consumption (V˙O2), HR at the second minute after INC, and muscle tissue saturation index at exhaustion (R = 0.644). In addition, age was linearly correlated with R_lim (adjusted R = −0.518, p < 0.0001). In conclusion, the recovery rates for V˙O2 and HR after the incremental test, and muscle saturation index at exhaustion, were the major physiological factors related to HIIT performance. These findings provide insights into the role of the recovery phase after maximal INC exercise testing. Future research investigating a combination of INC and HIIT testing to determine training-induced performance improvement is warranted.

High-intensity exercise improves cognitive function and hippocampal brain-derived neurotrophic factor expression in obese mice maintained on high-fat diet

We wanted to find the intensity of exercise that could increase brain- derived neurotrophic factor (BDNF) expression and improve spatial learning and memory without dietary control. C57BL/6 mice were fed a 60% high-fat diet (HFD) for 6 weeks to induce obesity. Obesity-induced mice were exercised on a treadmill for 8 weeks at various exercise in-tensities: HFD-control (n=7), HFD-low-intensity exercise (HFD-LIE, n= 7, 12 m/min for 75 min), HFD-middle intensity exercise (HFD-MIE, n=7, 15 m/min for 60 min) and HFD-high-intensity exercise (HFD-HIE, n=7, 18 m/min for 50 min). One week before sacrificing mice, the Morris wa-ter maze test was performed, and the hippocampus was immediately removed after sacrifice. The expression levels of BDNF (encoded by the gene Bdnf) and tropomyosin receptor kinase B (TrkB) in the hippo-campus were analyzed by quantitative real-time reverse transcription- polymerase chain reaction and western blot. In the last probe test of the Morris water maze test, occupancy in the target quadrant was sig-nificantly higher in the HFD-HIE group (P<0.05) than in the other groups. In addition, mRNA expression from the Bdnf promoter region was found to be significantly higher in the HFD-HIE group than in the other groups (P<0.001). Although there were some differences in the levels of signifi-cance, the expression levels of both BDNF and TrkB were significantly higher in the HFD-HIE group than in the other groups. Therefore, rela-tively high-intensity aerobic exercise can resist the adverse effects of a high-fat diet on the brain without dietary control.