Effect of Acute Altitude Exposure on Anaerobic Threshold Assessed by a Novel Electrocardiogram-Based Method

Background: Acute altitude has a relevant impact on exercise physiology and performance. Therefore, the positive impact on the performance level is utilized as a training strategy in professional as well as recreational athletes. However, ventilatory thresholds (VTs) and lactate thresholds (LTs), as established performance measures, cannot be easily assessed at high altitudes. Therefore, a noninvasive, reliable, and cost-effective method is needed to facilitate and monitor training management at high altitudes. High Alt Med Biol. 25:94-99, 2024. Methods: In a cross-sectional setting, a total of 14 healthy recreational athletes performed a graded cycling exercise test at sea level (Munich, Germany: 512 m/949 mbar) and high altitude (Zugspitze: 2,650 m/715 mbar). Anaerobic thresholds (ATs) were assessed using a novel method based on beat-to-beat repolarization instability (dT) detected by Frank-lead electrocardiogram (ECG) monitoring. The ECG-based ATs (ATdT°) were compared to routine LTs assessed according to Dickhuth and Mader. Results: After acute altitude exposure, a decrease in AT was detected using a novel ECG-based method (ATdT°: 159.80 ± 52.21 W vs. 134.66 ± 34.91 W). AtdT° levels correlated significantly with LTDickhuth and LTMader, at baseline (rDickhuth/AtdT° = 0.979; p < 0.001) (rMader/AtdT° = 0.943; p < 0.001), and at high altitude (rDickhuth/AtdT° = 0.969; p < 0.001) (rMader/AtdT° = 0.942; p < 0.001). Conclusion: Assessment of ATdT is a reliable method to detect performance alterations at altitude. This novel method may facilitate the training management of athletes at high altitudes.

Do freedivers and spearfishermen differ in local muscle oxygen saturation and anaerobic power?

BACKGROUND

Freediving is defined as an activity where athletes repetitively dive and are exposed to long efforts with limited oxygen consumption. Therefore, anaerobic features are expected to be an important facet of diving performance. This study aimed to investigate differences in anaerobic capacity and local muscle oxygenation in spearfisherman and freedivers.

METHODS

The sample of participants included 17 male athletes (nine freedivers, and eight spearfishermen), with an average age of 37.0±8.8 years, training experience of 10.6±9.5 years, body mass of 82.5±9.5 kg and height of 184.2±5.7 cm. Anthropometric characteristics included: body mass, body height, seated height, and body fat percentage. Wingate anaerobic test was conducted, during which local muscle oxygenation was measured with a NIRS device (Moxy monitor). Wingate power outputs were measured (peak power [W/kg] and average power [W/kg]), together with muscle oxygenation variables (baseline oxygen saturation [%], desaturation slope [%/s], minimum oxygen saturation [%], half time recovery [s], and maximum oxygen saturation [%]).

RESULTS

The differences were not obtained between freedivers and spearfisherman in power outputs (peak power (9.24±2.08 spearfisherman; 10.68±1.04 freedivers; P=0.14); average power (6.85±0.95 spearfisherman; 7.44±0.60 freedivers; P=0.15) and muscle oxygenation parameters. However, analysis of effect size showed a moderate effect in training experience (0.71), PP (0.89), AP (0.75), Desat slope mVLR (0.66), half time recovery mVLR (0.90).

CONCLUSIONS

The non-existence of differences between freedivers and spearfishermen indicates similar training adaptations to the anaerobic demands. However, the results show relatively low anaerobic capacities of our divers that could serve as an incentive for the further development of these mechanisms.

Estimated standard values of aerobic capacity according to sex and age in a Japanese population: A scoping review

Aerobic capacity is a fitness measure reflecting the ability to sustain whole-body physical activity as fast and long as possible. Identifying the distribution of aerobic capacity in a population may help estimate their health status. This study aimed to estimate standard values of aerobic capacity (peak oxygen uptake [Formula: see text] and anaerobic threshold [AT]/kg) for the Japanese population stratified by sex and age using a meta-analysis. Moreover, the comparison of the estimated standard values of the Japanese with those of other populations was performed as a supplementary analysis. We systematically searched original articles on aerobic capacity in the Japanese population using PubMed, Ichushi-Web, and Google Scholar. We meta-analysed [Formula: see text] (total: 78,714, men: 54,614, women: 24,100) and AT (total: 4,042, men: 1,961, women: 2,081) data of healthy Japanese from 21 articles by sex and age. We also searched, collected and meta-analysed data from other populations. Means and 95% confidence intervals were calculated. The estimated standard values of [Formula: see text] (mL/kg/min) for Japanese men and women aged 4-9, 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, and 70-79 years were 47.6, 51.2, 43.2, 37.2, 34.5, 31.7, 28.6, and 26.3, and 42.0, 43.2, 33.6, 30.6, 27.4, 25.6, 23.4, and 23.1, respectively. The AT/kg (mL/kg/min) for Japanese men and women aged 20-29, 30-39, 40-49, 50-59, 60-69, and 70-79 years were 21.1, 18.3, 16.8, 15.9, 15.8, and 15.2, and 17.4, 17.0, 15.7, 15.0, 14.5, and 14.2, respectively. Herein, we presented the estimated standard values of aerobic capacity according to sex and age in a Japanese population. In conclusion, aerobic capacity declines with ageing after 20-29 years of age. Additionally, aerobic capacity is lower in the Japanese population than in other populations across a wide range of age groups. Standard value estimation by meta-analysis can be conducted in any country or region and for public health purposes.

Prediction of Relevant Training Control Parameters at Individual Anaerobic Threshold without Blood Lactate Measurement

BACKGROUND

Active exercise therapy plays an essential role in tackling the global burden of obesity. Optimizing recommendations in individual training therapy requires that the essential parameters heart rate HR(IAT) and work load (W/kg(IAT) at individual anaerobic threshold (IAT) are known. Performance diagnostics with blood lactate is one of the most established methods for these kinds of diagnostics, yet it is also time consuming and expensive.

METHODS

To establish a regression model which allows HR(IAT) and (W/kg(IAT) to be predicted without measuring blood lactate, a total of 1234 performance protocols with blood lactate in cycle ergometry were analyzed. Multiple linear regression analyses were performed to predict the essential parameters (HR(IAT)) (W/kg(IAT)) by using routine parameters for ergometry without blood lactate.

RESULTS

HR(IAT) can be predicted with an RMSE of 8.77 bpm (p < 0.001), R² = 0.799 (|R| = 0.798) without performing blood lactate diagnostics during cycle ergometry. In addition, it is possible to predict W/kg(IAT) with an RMSE (root mean square error) of 0.241 W/kg (p < 0.001), R² = 0.897 (|R| = 0.897).

CONCLUSIONS

It is possible to predict essential parameters for training management without measuring blood lactate. This model can easily be used in preventive medicine and results in an inexpensive yet better training management of the general population, which is essential for public health.

Exercise Performance in Adolescents With Fontan Physiology (from the Pediatric Heart Network Fontan Public Data Set)

In the pediatric population, exercise capacity differs between females and males and the gap widens through adolescence. However, specific age- and sex-based changes in adolescents with congenital heart disease and Fontan palliation have not been reported. The purpose of the current study is to identify age- and sex-specific changes in exercise performance at peak and ventilatory anaerobic threshold (AT) for adolescents with Fontan physiology. Retrospective review of the Pediatric Heart Network Fontan cross sectional study (Fontan 1) public use dataset. Comparisons were made for peak and AT exercise parameters for females and males at 2-year age intervals. In addition, normative values were generated by sex and age at 2-year intervals. χ² test was used for comparison for categorical variables. Changes in exercise parameters between age groups by sex were compared by ANOVA with post-hoc analysis. Exercise testing was performed in 411 patients. AT was reached in 317 subjects (40% female), of whom, 166 (43% female) reached peak exercise. Peak oxygen consumption decreased 32% through adolescence in females and did not have the typical increase through adolescence for males. Oxygen consumption at AT also decreased with age in both sexes. In conclusion, age- and sex-based exercise performance for adolescents with Fontan physiology are predictably low, but there are additional significant decreases through adolescence for this population, especially in females. We have established normative exercise values for several parameters for this population which will better identify at risk patients and allow for earlier intervention.

Relationship between the face scale for rating of perceived exertion and physiological parameters in older adults and patients with atrial fibrillation

BACKGROUND

The Borg scale is used to determine exercise intensity in rehabilitation but can be difficult for older adults to understand. By contrast, face scale that are used to evaluate pain are much easier to understand thanks to the inclusion of illustrations. On the other hand, the prevalence of atrial fibrillation (AF) increases with age. This study aimed to determine the validity of the face scale for rating perceived exertion (RPE-face scale) in older adults and patients with AF during cardiopulmonary exercise test. Furthermore, the relationship between face scale and anaerobic threshold (AT) was also investigated.

METHODS

A total of 90 patients with sinus rhythm (SR) (74 men, 16 women) and 22 with AF were enrolled. Participants' responses were recorded using the RPE-face scale and compared with exercise intensity, heart rate, oxygen uptake, and minute ventilation during the exercise test. We determined the AT by the V-slope method.

RESULTS

Correlations between RPE-face scale and physiological parameters were significantly positive for men with SR and women with SR and AF. However, differences in the correlation coefficient between age and SR or AF were not statistically significant. The cutoff value for AT of the RPE-face scale was "4," showing high sensitivity and specificity.

CONCLUSIONS

The RPE-face scale can be used to determine the intensity of physical exercise, unaffected by age, gender, SR, or AF.

Laminar flow ventilation system to prevent airborne infection during exercise in the COVID-19 crisis: A single-center observational study

Particulate generation occurs during exercise-induced exhalation, and research on this topic is scarce. Moreover, infection-control measures are inadequately implemented to avoid particulate generation. A laminar airflow ventilation system (LFVS) was developed to remove respiratory droplets released during treadmill exercise. This study aimed to investigate the relationship between the number of aerosols during training on a treadmill and exercise intensity and to elucidate the effect of the LFVS on aerosol removal during anaerobic exercise. In this single-center observational study, the exercise tests were performed on a treadmill at Running Science Lab in Japan on 20 healthy subjects (age: 29±12 years, men: 80%). The subjects had a broad spectrum of aerobic capacities and fitness levels, including athletes, and had no comorbidities. All of them received no medication. The exercise intensity was increased by 1-km/h increments until the heart rate reached 85% of the expected maximum rate and then maintained for 10 min. The first 10 subjects were analyzed to examine whether exercise increased the concentration of airborne particulates in the exhaled air. For the remaining 10 subjects, the LFVS was activated during constant-load exercise to compare the number of respiratory droplets before and after LFVS use. During exercise, a steady amount of particulates before the lactate threshold (LT) was followed by a significant and gradual increase in respiratory droplets after the LT, particularly during anaerobic exercise. Furthermore, respiratory droplets ≥0.3 μm significantly decreased after using LFVS (2120800±759700 vs. 560 ± 170, p<0.001). The amount of respiratory droplets significantly increased after LT. The LFVS enabled a significant decrease in respiratory droplets during anaerobic exercise in healthy subjects. This study's findings will aid in exercising safely during this pandemic.

High-Intensity 10-s Work: 5-s Recovery Intermittent Training Improves Anaerobic and Aerobic Performances

Purpose and Methods: To compare the effects of a set of 12-30 min, maximal effort, constant load cycle bouts (HICT) to 12 short work: shorter rest (10 s: 5 s) interval sessions (INT) of similar duration and effort, performed on alternate days over 4 weeks, on performance and V̇O₂ l^.min^-1. INT sessions consisted of repeated cycles of 10 s work followed by 5 s of recovery for 30 min. Fourteen male athletes (83 kg ± 6, 24year ± 2) were randomly assigned to HICT (n = 7) or INT (n = 7) training. Pre- and post-power output (PO), V̇O₂ and V̇O_2peak, during 60s, 3 min, and ramp (RAMP) tests were collected Results: Between group comparisons showed increased mean PO, pre- to post-INT training (p = .026) over the last min of the 3-min test whereas PO post-HICT training declined. INT showed greater training effects on the 60 s test than HCIT (INT 506 ± 45 to 535 ± 55 W; p = .002, Cd = .57; HCIT 513 ± 78 to 548 ± 83 W; p = .02, Cd = 27). RAMP peak PO and V̇O_2peak increased within both groups (INT 341 ± 63 to 370 ± 48 W, p = .002, Cd = 0.52; HICT 332 ± 45 to 353 ± 44 W, p = .006, Cd = .53; 3.73 ± 0.68 to 4.06 ± 0.63 L·min^-1, p = .001, Cd = .50; 3.75 ± 0.62 to 4.09 ± 0.52 L·min^-1, p = .002, Cd = .59). Conclusion(s): These results show that utilizing this novel short work: shorter rest (10 s: 5 s) interval training paradigm will elicit better performances in moderate duration performances compared to continuous training of the same duration, effort, and frequency.

Exercise intensity prescription in cancer survivors: ventilatory and lactate thresholds are useful submaximal alternatives to VO2peak

PURPOSE

Most studies with cancer survivors use percentages of peak oxygen uptake (VO2peak) for intensity prescription. Lactate or ventilatory thresholds might be useful submaximal alternatives, but this has never been investigated. Therefore, we aimed at comparing three training sessions prescribed using %VO2peak (reference), lactate thresholds, and ventilatory thresholds in terms of meeting the vigorous-intensity zone, physiological, and psychological responses.

METHODS

Twenty breast (58 ± 10 years) and 20 prostate cancer survivors (68 ± 6 years), 3.6 ± 2.4 months after primary therapy, completed a maximal cardiopulmonary exercise test and three vigorous training sessions in randomized order: 38 min of cycling at 70% VO2peak (M-VO2peak), 97% of individual anaerobic lactate threshold (M-IAT), and 67% between ventilatory thresholds 1 and 2 (M-VT). Heart rate (HR), blood lactate concentration (bLa), perceived exertion, and enjoyment were assessed.

RESULTS

Cancer survivors exercised at 75 ± 23, 85 ± 18, and 79 ± 19 W during M-VO2peak, M-IAT, and M-VT (p > .05). Sessions could not be completed in 3, 8, and 6 cases. Session completers showed HR of 82 ± 7, 83 ± 9, and 84 ± 8 %HRpeak and bLa of 3.7 ± 1.9, 3.9 ± 0.9, and 3.9 ± 1.5 mmol·l-1, which was not different between sessions (p > .05). However, variance in bLa was lower in M-IAT compared to M-VO2peak (p = .001) and to M-VT (p = .022).

CONCLUSION

All intensity prescription methods on average met the targeted intensity zone. Metabolic response was most homogeneous when using lactate thresholds.

IMPLICATIONS FOR CANCER SURVIVORS

Submaximal thresholds are at least as useful as VO2peak for intensity prescription in cancer survivors. Overall, slightly lower percentages should be chosen to improve durability of the training sessions.

Hyperglycaemia is associated with impaired muscle signalling and aerobic adaptation to exercise

Increased aerobic exercise capacity, as a result of exercise training, has important health benefits. However, some individuals are resistant to improvements in exercise capacity, probably due to undetermined genetic and environmental factors. Here, we show that exercise-induced improvements in aerobic capacity are blunted and aerobic remodelling of skeletal muscle is impaired in several animal models associated with chronic hyperglycaemia. Our data point to chronic hyperglycaemia as a potential negative regulator of aerobic adaptation, in part, via glucose-mediated modifications of the extracellular matrix, impaired vascularization and aberrant mechanical signalling in muscle. We also observe low exercise capacity and enhanced c-Jun N-terminal kinase activation in response to exercise in humans with impaired glucose tolerance. Our work indicates that current shifts in dietary and metabolic health, associated with increasing incidence of hyperglycaemia, might impair muscular and organismal adaptations to exercise training, including aerobic capacity as one of its key health outcomes.

Effects of Aerobic and Anaerobic Fatigue Exercises on Postural Control and Recovery Time in Female Soccer Players

Sixteen female soccer players (age = 20.19 ± 1.52 years; body mass = 56.52 ± 4.95 kg; body height = 164.81 ± 4.21 cm) with no history of lower extremity injury participated in the study. The Biodex SD Balance system was used to determine the non-dominant single-leg stability. In anaerobic exercise, each subject performed four maximal cycling efforts against a resistance equivalent to 0.075 kg/body mass for 30 s with three-minute rest intervals. In aerobic exercise, subjects performed the Bruce protocol on a motorized treadmill. After each exercise, subjects subsequently performed a single-leg stability test and then repeated the same test for four times with five-minute passive rest periods. In accordance with the results, it was found that the impairment observed right after the aerobic loading was higher (p < 0.001) compared to the anaerobic one. However, the time-related deterioration in both aerobic and anaerobic loadings was similar. The B-pre value was lower than B_post and B₅ (p < 0.01) and B₁₀ (p < 0.05) in both conditions. Subjects could reach the initial balance level at B₁₅ after aerobic and anaerobic loadings. The lactate level did not reach resting value even after 20 min of both fatigue protocols. Although the fatigue after aerobic and aerobic exercise negatively affects a single-leg dynamic balance level, single leg balance ability returns to the baseline status after 10 min of passive recovery duration.

Application of stepper in cardiopulmonary exercise test for patients with hemiplegia

A method to perform exercise testing for patients with hemiplegia is unavailable though over half of them have cardio-pulmonary disorders. We aimed to assess the reliability and validity of using a stepper in cardiopulmonary exercise testing (CPET) in this population.14 stroke patients with hemiplegia who failed to ride the stationary bike were included. Exclusion criteria included manual muscle strength ≦1 in the lower extremity, and conventional contraindications of CPET. They underwent CPET twice by using a stepper to evaluate test-retest reliability and validity. Additionally, 10 healthy participants underwent CPET twice on the cycle ergometer and stepper respectively.In the test-retest, the ratio of two-time difference to mean was 5.0, 3, 11.3 and 12.0% on average for peak oxygen consumption, peak heart rate (HR), anaerobic threshold and minute ventilation - carbonic dioxide production slope respectively. Cronbach's alpha coefficient of peak oxygen consumption and anaerobic threshold were 0.992 and 0.919. In the stepper exercise testing of the hemiplegic participants, the ratio of peak HR to age-predicted maximal HR was 75% on average. Peak respiratory exchange ratio (mean ± standard deviation = 1.17 ± 0.08) was not different from that of healthy controls (1.21 ± 0.09). Notably, VO2 trajectory in relation to work rate is nonlinear and different in the rest-retest.This is the first research to study CPET variables in detail using stepper in patients with hemiplegia. CPET variables associated with peak are valid and reliable; nonetheless, those with sub-maximum are not. The study provides a method to do exercise testing for the patients with hemiplegia and its notice in application.

Healthy active older adults have enhanced K+ channel-dependent endothelial vasodilatory mechanisms

Microvascular endothelial dysfunction, a precursor to atherosclerotic cardiovascular disease, increases with aging. Endothelium-derived hyperpolarizing factors (EDHFs), which act through K+ channels, regulate blood flow and are important to vascular health. It is unclear how EDHFs change with healthy aging. To evaluate microvascular endothelial reliance on K+ channel-mediated dilation as a function of age in healthy humans. Microvascular function was assessed using intradermal microdialysis in healthy younger (Y; n = 7; 3 M/4 W; 26 ± 1 yr) and older adults (O; n = 12; 5 M/7 W; 64 ± 2 yr) matched for V̇o2peak (Y: 39.0 ± 3.8, O: 37.6 ± 3.1 mL·kg-1·min-1). Participants underwent graded local infusions of: the K+ channel activator Na2S (10-6 to 10-1 M), acetylcholine (ACh, 10-10 to 10-1 M), ACh + the K+ channel inhibitor tetraethylammonium (TEA; 25 or 50 mM), and ACh + the nitric oxide synthase-inhibitor l-NAME (15 mM). Red blood cell flux was measured with laser-Doppler flowmetry and used to calculate cutaneous vascular conductance (CVC; flux/mean arterial pressure) as a percentage of each site-specific maximum (%CVCmax, 43°C+28 mM sodium nitroprusside). The %CVCmax response to Na2S was higher in older adults (mean, O: 51.7 ± 3.9% vs. Y: 36.1 ± 5.3%; P = 0.03). %CVCmax was lower in the ACh+TEA vs. the ACh site starting at 10-5 M (ACh: 34.0 ± 5.7% vs. ACh+TEA: 19.4 ± 4.5%; P = 0.002) in older and at 10-4 M (ACh: 54.5 ± 9.4% vs. ACh+TEA: 31.2 ± 6.7%; P = 0.0002) in younger adults. %CVCmax was lower in the ACh+l-NAME vs. the ACh site in both groups starting at 10-4 M ACh (Y: P < 0.001; O: P = 0.02). Healthy active older adults have enhanced K+ channel-dependent endothelial vasodilatory mechanisms, suggesting increased responsiveness to EDHFs with age.

Effect of an Eleven-Day Altitude Training Program on Aerobic and Anaerobic Performance in Adolescent Runners

Background and Objectives: We evaluated the effect of an eleven-day altitude training camp on aerobic and anaerobic fitness in trained adolescent runners. Materials and Methods: Twenty adolescent (14–18 yrs) middle- and long-distance runners (11 males and 9 females; 16.7 ± 0.8 yrs), with at least two years of self-reported consistent run training, participated in this study. Eight of the subjects (4 females/4 males) constituted the control group, whereas twelve subjects (5 females/7 males) took part in a structured eleven-day altitude training camp, and training load was matched between groups. Primary variables of interest included changes in aerobic (VO₂max) and anaerobic (30 s Wingate test) power. We also explored the relationships between running velocity and blood lactate levels before and after the altitude training camp. Results: Following 11 days of altitude training, desirable changes (p < 0.01) in VO₂max (+13.6%), peak relative work rate (+9.6%), and running velocity at various blood lactate concentrations (+5.9%–9.6%) were observed. Meanwhile, changes in Wingate anaerobic power (+5.1%) were statistically insignificant (p > 0.05). Conclusions: Short duration altitude appears to yield meaningful improvements in aerobic but not anaerobic power in trained adolescent endurance runners.

Performance of cardiopulmonary exercise testing for the prediction of post-operative complications in non cardiopulmonary surgery: A systematic review

INTRODUCTION

Cardiopulmonary exercise testing (CPET) is widely used within the United Kingdom for preoperative risk stratification. Despite this, CPET's performance in predicting adverse events has not been systematically evaluated within the framework of classifier performance.

METHODS

After prospective registration on PROSPERO (CRD42018095508) we systematically identified studies where CPET was used to aid in the prognostication of mortality, cardiorespiratory complications, and unplanned intensive care unit (ICU) admission in individuals undergoing non-cardiopulmonary surgery. For all included studies we extracted or calculated measures of predictive performance whilst identifying and critiquing predictive models encompassing CPET derived variables.

RESULTS

We identified 36 studies for qualitative review, from 27 of which measures of classifier performance could be calculated. We found studies to be highly heterogeneous in methodology and quality with high potential for bias and confounding. We found seven studies that presented risk prediction models for outcomes of interest. Of these, only four studies outlined a clear process of model development; assessment of discrimination and calibration were performed in only two and only one study undertook internal validation. No scores were externally validated. Systematically identified and calculated measures of test performance for CPET demonstrated mixed performance. Data was most complete for anaerobic threshold (AT) based predictions: calculated sensitivities ranged from 20-100% when used for predicting risk of mortality with high negative predictive values (96-100%). In contrast, positive predictive value (PPV) was poor (2.9-42.1%). PPV appeared to be generally higher for cardiorespiratory complications, with similar sensitivities. Similar patterns were seen for the association of Peak VO2 (sensitivity 85.7-100%, PPV 2.7-5.9%) and VE/VCO2 (Sensitivity 27.8%-100%, PPV 3.4-7.1%) with mortality.

CONCLUSIONS

In general CPET's 'rule-out' capability appears better than its ability to 'rule-in' complications. Poor PPV may reflect the frequency of complications in studied populations. Our calculated estimates of classifier performance suggest the need for a balanced interpretation of the pros and cons of CPET guided pre-operative risk stratification.

Acute fatigue affects reaction times and reaction consistency in Mixed Martial Arts fighters

Mixed Martial Arts (MMA) is a multielement combat sport where fighters need to quickly react to an opponent’s movements under fatigued conditions. Research indicates that fast reaction time is important in many sports, but the effect of fatigue has shown negative, null, or even positive influences on reaction time. However, few studies have been conducted in a controlled setting, especially using MMA figthers, whose matches are frequently resolved in a split-second. Therefore, this study investigated whether acute neuromuscular fatigue affects reaction and movement times, and their consistency in MMA fighters (N = 45). Before and after an upper-body Wingate test, a simple visual reaction time task was completed. Results showed a significant negative effect of fatigue on the reaction times and their consistency, with longer reactions (1.5% change) and lower consistency (14.7% change) after the Wingate test. Further, greater amounts of fatigue during the Wingate test seemed to negatively affect the consistency of post-Wingate movement time. Due to cumulative fatigue and the dynamic nature of MMA, our data indicate that not only the decrements in aerobic and anaerobic power likely affect a fighter’s performance, but their reaction time and motor time may also be compromised during a fight.

Polarized and Pyramidal Training Intensity Distribution: Relationship with a Half-Ironman Distance Triathlon Competition

The purpose of the present study was to relate the training intensity distribution with performance in a Half-Ironman distance triathlon competition. A total of 18 recreational-level triathletes were divided into two training groups according to their training intensity distribution: Polarized (POL) and Pyramidal (PYR). Prior to the specific training period of the study, subjects performed a ramp-protocol test, running and cycling to determine ventilatory thresholds (VT) through gas-exchange analysis. For swimming, subjects performed an 800-metre test to establish their training zones. Training was quantified based on the cumulative time spent in 3 intensity zones: zone 1 (low intensity, <VT1), zone 2 (moderate intensity, VT1-VT2) and zone 3 (high intensity >VT2). POL competed 84.5%/4.2%/11.3% and PYR 77.9%/18.8%/3.3% of total training time for zones 1,2 and 3 respectively. The goal of the training period was a half Ironman distance triathlon. Training time in zone 2 inversely correlated with swimming and cycling race time in POL and with running and total race time in PYR. Power at VT2 on bike and speed at VT2 as well as maximum aerobic power and speed in the physiological post test inversely correlated with bike and run segment respectively and with total race time. These results suggest that training time in zone 2 was related with better performance on a Half-Ironman race in amateur triathletes. Future experimental research is needed to clarify the importance of training intensity distribution regarding performance.

Lactate Equivalent for Maximal Lactate Steady State Determination in Soccer

Purpose: The association between an overlooked classical Lactate Threshold (LT), named "Minimum Lactate Equivalent" (LE_min), with Maximal Lactate Steady State (MLSS) has been recently described with good MLSS prediction results in endurance-trained runners. This study aimed to determine the applicability of LE_min to predict MLSS in lower aerobic-conditioned individuals compared to well-established blood lactate-related thresholds (BLTs). Method: Fifteen soccer players [velocity at MLSS (MLSS_V) 13.2 ± 1.0 km·h^-1; coefficient of variation (CV) 7.6%] conducted a submaximal discontinuous incremental running test to determine BLTs and 3-6 constant velocity running tests to determine MLSS_V. Results: LE_min did not differ from conventional LTs (p > .05) and was 24% lower than MLSS (p < .001; ES: 3.26). Among LTs, LE_min best predicted MLSS_V (r = 0.83; p < .001; SEE = 0.59 km·h^-1). There was no statistical difference between MLSS and estimated MLSS using LE_min prediction formula (p = .99; ES: 0.001). Mean bias and limits of agreement were 0.00 ± 0.58 km·h^-1 and ±1.13 km·h^-1, respectively. LE_min best predicted MLSS_V (r = 0.92; p < .001; SEE = 0.54 km·h^-1) in the pooled data of soccer players and endurance-trained runners of the previous study (n = 28; MLSS_V range 11.2-16.5 km·h^-1; CV 9.8%). Conclusion: Results support LE_min to be one of the best single predictors of MLSS. This study is the sole study providing specific operational regression equations to estimate the impractical gold standard MLSS_V in soccer players by means of a BLT measured during a submaximal single-session test.

Effects of the Menstrual Cycle on Running Economy: Oxygen Cost Versus Caloric Cost

Purpose: This study investigated the effects of the menstrual cycle on running economy (RE). Method: Eleven eumenorrheic female athletes (mean age: 21.18 ± 3.65 years, height: 170.2 ± 6.6 cm, VO₂max: 49.25 ± 9.15 mL·kg^-1·min^-1, and menstrual cycle: 29.8 ± 0.98 days) were tested for anthropometric variables, physiological responses (oxygen consumption [VO₂], blood lactate [LA], heart rate [HR], and respiratory exchange ratio [RER]) at rest and while running. The RE was measured at speeds of 75%, 85%, and 95% of the lactate threshold at 3.5 mmol·L^-1 during the follicular (FP) and luteal phases (LP) of the menstrual cycle. The RE was evaluated as oxygen consumption (mL·kg·min^-1 [O_{2C_}min], mL·kg^-1·km^-1 [O_{2C_}km]) and caloric unit cost (kcal·kg^-1·km^-1 [E_C]) during both phases. Results: There were no significant differences in body composition or resting physiological measurements between the LP and FP (p > .05). Physiological responses measured during RE tests were similar in both phases (p > .05). The RE measured as O_{2C_}min, O_{2C_}km, and E_C was significantly lower during the LP than during the FP (p < .05). The RE defined as O_{2C_} min significantly increased with speed (p < .05), but RE defined as O_{2C_}km and E_C was unaffected by speed increment (p > .05). Conclusions: The RE is better in the LP than the FP and is independent of running speed when RE is evaluated as O_{2C_}km and E_C. The menstrual cycle had no effect on body composition and physiological variables measured at rest.

Individualized Accelerometer Activity Cut-Points for the Measurement of Relative Physical Activity Intensity Levels

Purpose: The aim of this study was to compare the widely used accelerometer activity cut-points derived from the absolute moderate intensity recommendation (3‒6 METs), with relative intensity cut-points according to maximal cardiorespiratory fitness (46%‒63% V˙O2max ) and to individual lactate thresholds (LT1 and LT2) in postmenopausal women. Method: Thirty postmenopausal women performed several exercise tests with measures of heart rate, blood lactate, accelerometer activity counts and oxygen consumption. Individual regressions were developed to derive the accelerometer activity counts at absolute and relative moderate intensity recommendations and at individual LTs. Results: The activity counts calculated at the lower moderate intensity boundary were lower for the absolute 3 METs threshold (2026 ± 808 ct·min^-1) compared to relative 46 % V˙O2max intensity threshold (p < .01, ES: 1.95) and LT1 (p < .01, ES: 2.27), which corresponded to 4.6 ± 0.7 METs. The activity counts at the upper moderate intensity boundary were higher for LT2 (7249 ± 2499 ct·min^-1) compared to the absolute 6 METs threshold (p < .01, ES: 0.72) and relative 63% V˙O2max intensity threshold (p < .01, ES: 0.55). The interindividual variability in activity counts at relative intensity thresholds was high (CV = 30-34%), and was largely explained by cardiorespiratory fitness level (R² = ~ 50%). Conclusion: Individually tailored (relative to V˙O2max or submaximal LTs) rather than fixed accelerometer intensity cut-points derived from the classic absolute moderate physical activity intensity (3-6 METs) would result in a more accurate measurement of an individual´s activity levels and reduce the risk of overestimating or underestimating physical activity.

The characterization of the transit through the anaerobic threshold based on relationships between RR and QRS cardiac intervals

This paper aims to develop a novel computational technique for the detection of the transit through the anaerobic threshold. This technique uses only cardiac intervals derived from the electrocardiogram and is based on algebraic relationships between RR and QRS intervals. Electrocardiograms are measured during the load and the recovery processes. Algebraic relationships between cardiac intervals are used not only to identify the anaerobic threshold but also to characterise individual features of the person during the transit through the threshold. The ratio between carbon dioxide and oxygen in the exhaled air is used to validate the results. The algebraic relationship between cardiac intervals serves as a stand-alone indicator for both the determination of the anaerobic threshold and the characterization of the performance of the person during the load and the recovery processes.

Prediction of the Wingate anaerobic mechanical power outputs from a maximal incremental cardiopulmonary exercise stress test using machine-learning approach

The Wingate Anaerobic Test (WAnT) is a short-term maximal intensity cycle ergometer test, which provides anaerobic mechanical power output variables. Despite the physiological significance of the variables extracted from the WAnT, the test is very intense, and generally applies for athletes. Our goal, in this paper, was to develop a new approach to predict the anaerobic mechanical power outputs using maximal incremental cardiopulmonary exercise stress test (CPET). We hypothesized that maximal incremental exercise stress test hold hidden information about the anaerobic components, which can be directly translated into mechanical power outputs. We therefore designed a computational model that included aerobic variables (features), and used a new computational \ predictive algorithm, which enabled the prediction of the anaerobic mechanical power outputs. We analyzed the chosen predicted features using clustering on a network. For peak power (PP) and mean power (MP) outputs, the equations included six features and four features, respectively. The combination of these features produced a prediction model of r = 0.94 and r = 0.9, respectively, on the validation set between the real and predicted PP/MP values (P< 0.001). The newly predictive model allows the accurate prediction of the anaerobic mechanical power outputs at high accuracy. The assessment of additional tests is desired for the development of a robust application for athletes, older individuals, and/or non-healthy populations.

The cardiopulmonary exercise test grey zone; optimising fitness stratification by application of critical difference

BACKGROUND

Cardiorespiratory fitness can inform patient care, although to what extent natural variation in CRF influences clinical practice remains to be established. We calculated natural variation for cardiopulmonary exercise test (CPET) metrics, which may have implications for fitness stratification.

METHODS

In a two-armed experiment, critical difference comprising analytical imprecision and biological variation was calculated for cardiorespiratory fitness and thus defined the magnitude of change required to claim a clinically meaningful change. This metric was retrospectively applied to 213 patients scheduled for colorectal surgery. These patients underwent CPET and the potential for misclassification of fitness was calculated. We created a model with boundaries inclusive of natural variation [critical difference applied to oxygen uptake at anaerobic threshold (V˙O2-AT): 11 ml O2 kg-1 min-1, peak oxygen uptake (V˙O2 peak): 16 ml O2 kg-1 min-1, and ventilatory equivalent for carbon dioxide at AT (V̇E/V̇CO2-AT): 36].

RESULTS

The critical difference for V˙O2-AT, V˙O2 peak, and V˙E/V˙CO2-AT was 19%, 13%, and 10%, respectively, resulting in false negative and false positive rates of up to 28% and 32% for unfit patients. Our model identified boundaries for unfit and fit patients: AT <9.2 and ≥13.6 ml O2 kg-1 min-1, V˙O2 peak <14.2 and ≥18.3 ml kg-1 min-1, V˙E/V˙CO2-AT ≥40.1 and <32.7, between which an area of indeterminate-fitness was established. With natural variation considered, up to 60% of patients presented with indeterminate-fitness.

CONCLUSIONS

These findings support a reappraisal of current clinical interpretation of cardiorespiratory fitness highlighting the potential for incorrect fitness stratification when natural variation is not accounted for.

Advances of the reverse lactate threshold test: Non-invasive proposal based on heart rate and effect of previous cycling experience

Our first aim was to compare the anaerobic threshold (AnT) determined by the incremental protocol with the reverse lactate threshold test (RLT), investigating the previous cycling experience effect. Secondarily, an alternative RLT application based on heart rate was proposed. Two groups (12 per group-according to cycling experience) were evaluated on cycle ergometer. The incremental protocol started at 25 W with increments of 25 W at each 3 minutes, and the AnT was calculated by bissegmentation, onset of blood lactate concentration and maximal deviation methods. The RLT was applied in two phases: a) lactate priming segment; and b) reverse segment; the AnT (AnTRLT) was calculated based on a second order polynomial function. The AnT from the RLT was calculated based on the heart rate (AnTRLT-HR) by the second order polynomial function. In regard of the Study 1, most of statistical procedures converged for similarity between the AnT determined from the bissegmentation method and AnTRLT. For 83% of non-experienced and 75% of experienced subjects the bias was 4% and 2%, respectively. In Study 2, no difference was found between the AnTRLT and AnTRLT-HR. For 83% of non-experienced and 91% of experienced subjects, the bias between AnTRLT and AnTRLT-HR was similar (i.e. 6%). In summary, the AnT determined by the incremental protocol and RLT are consistent. The AnT can be determined during the RLT via heart rate, improving its applicability. However, future studies are required to improve the agreement between variables.

Effect of sodium bicarbonate on prolonged running performance: A randomized, double-blind, cross-over study

BACKGROUND

The ability to sustain intense exercise seems to be partially limited by the body's capability to counteract decreases in both intra- and extracellular pH. While the influence of an enhanced buffering capacity via sodium bicarbonate (BICA) on short-term, high-intensity exercise performance has been repeatedly investigated, studies on prolonged endurance performances are comparatively rare, especially for running. The aim of the following study was to assess the ergogenic effects of an oral BICA substitution upon exhaustive intensive endurance running performance.

METHOD

In a double-blind randomized cross-over study, 18 trained runners (VO2peak: 61.2 ± 6.4 ml•min-1•kg-1) performed two exhaustive graded exercise tests and two constant load tests (30 main at 95% individual anaerobic threshold (IAT) followed by 110% IAT until exhaustion) after ingestion of either sodium bicarbonate (BICA) (0.3 g/kg) or placebo (4 g NaCl) diluted in 700 ml of water. Time to exhaustion (TTE) in the constant load test was defined as the main outcome measure. Throughout each test respiratory gas exchange measurements were conducted as well as determinations of heart rate, blood gases and blood lactate concentration.

RESULTS

TTE in the constant load test did not differ significantly between BICA and placebo conditions (BICA: 39.6 ± 5.6 min, placebo: 39.3 ± 5.6 min; p = 0.78). While pH in the placebo test dropped to a slightly acidotic value two minutes after cessation of exercise (7.34 ± 0.05) the value in the BICA trial remained within the normal range (7.41 ± 0.06) (p < 0.001). In contrast, maximum running speed (Vmax) in the exhaustive graded exercise test was significantly higher with BICA (17.4 ± 1.0 km/h) compared to placebo (17.1 ± 1.0 km/h) (p = 0.009). The numerical difference in maximum oxygen consumption (VO2peak) failed to reach statistical significance (BICA: 61.2 ± 6.4 ml•min-1•kg-1, placebo: 59.8 ± 6.4 ml•min-1•kg-1; p = 0.31). Maximum blood lactate was significantly higher with BICA compared to the corresponding placebo test (BICA: 11.1 ± 2.3 mmol/l, placebo: 8.9 ± 3.0 mmol/l; p < 0.001). At the end of exercise, an acidotic pH value was found in both exhaustive graded exercise tests (p = 0.002). BICA caused gastrointestinal side effects in 15 patients.

CONCLUSION

Maximal performance was enhanced significantly after BICA administration. The ergogenic effect of BICA in the exhaustive graded exercise test can most likely be attributed to an increased anaerobic glycolysis that is reflected by an accumulation of lactate. However, TTE in prolonged high-intensity running was not improved. Even at the end of exercise no severe metabolic acidosis was found. Metabolic acidification as one of the dominant factors causing muscular fatigue should therefore be reconsidered.

TRIAL REGISTRATION

German Clinical Trials Register (DRKS) DRKS00011284.

Blood lactate accumulation decreases during the slow component of oxygen uptake without a decrease in muscular efficiency

Pulmonary oxygen uptake ([Formula: see text]) slowly increases during exercise above the anaerobic threshold, and this increase is called the slow component of [Formula: see text]. The mechanism of the increase in [Formula: see text] is assumed to be due to increasing energy cost associated with increasingly inefficient muscle contraction. We hypothesized that the increase in [Formula: see text] would be accompanied by a constant or increasing rate of accumulation of blood lactate, indicating sustained anaerobic metabolism while [Formula: see text] increased. Ten male subjects performed cycle ergometry for 3, 6, and 9 min at a power output representing 60% of the difference between lactate threshold and maximal [Formula: see text] while [Formula: see text] and blood lactate accumulation were measured. Blood lactate accumulation decreased over time, providing the energy equivalent of (mean ± SD) 1586 ± 265, 855 ± 287, and 431 ± 392 ml of [Formula: see text] during 0-3, 3-6, and 6-9 min of exercise, respectively. As duration progressed, [Formula: see text] supplied 86.3 ± 2.0, 93.6 ± 1.9, and 96.8 ± 2.9% of total energy from 0 to 3, 3 to 6, and 6 to 9 min, respectively, while anaerobic contribution decreased. There was no change in total energy cost after 3 min, except that required by ventilatory muscles for the progressive increase in ventilation. The slow component of [Formula: see text] is accompanied by decreasing anaerobic energy contribution beyond 3 min during heavy exercise.

Comparison of bioenergetics of walking during a multistage incremental shuttle walk test and a 6-min walk test in active older adults

The goal of the present research was to compare the bioenergetics variability of walking, during the 6-min walk test (6-MWT) and a multistage incremental shuttle walk test (MISWT) in an active older population. Twenty-two healthy physically active older adults with a group mean age of 70.4 ± 5.8 years completed the 6-MWT and the MISWT. Heart rate (HR), walking speed and walking [Formula: see text]O₂ were measured throughout each test with a portable metabolic cart. Strong correlations were found for the [Formula: see text]O₂ peak and the walking speed (r = 0.91 and r = 0.89 respectively for 6-MWT and MISWT). Differences in [Formula: see text]O₂ peak values were analysed with a paired Student's t test. Repeated measures ANOVA were conducted to detect differences between tests. The Bland and Altman plot indicates that the average difference between both tests was 2.5 ml kg^-1 min^-1. MISWT [Formula: see text]O₂ peak means were significantly greater than the 6-MWT [Formula: see text]O₂ peak mean values (21.6 ± 5.3 vs. 18.9 ± 4.5 ml kg^-1 min^-1) which indicate bioenergetics differences between the two walking tests. Thus, the MISWT and 6-MWT elicited different walking [Formula: see text]O₂ peak and HR suggesting that the MISWT field test challenge the participants to a higher level of cardiovascular and respiratory stress. The walking [Formula: see text]O₂ peak recorded for the MISWT was significantly greater than the 6-MWT. Consequently, both tests seem to measure different facets of the aerobic capacity. MISWT seems to be a better indicator of maximal aerobic power whereas the 6-MWT provides more relevant information regarding aerobic endurance in aging population.

Oxygen uptake kinetics and energy system's contribution around maximal lactate steady state swimming intensity

The purpose of this study was to examine the oxygen uptake (V˙O2) kinetics and the energy systems’ contribution at 97.5, 100 and 102.5% of the maximal lactate steady state (MLSS) swimming intensity. Ten elite female swimmers performed three-to-five 30 min submaximal constant swimming bouts at imposed paces for the determination of the swimming velocity (v) at 100%MLSS based on a 7 x 200 m intermittent incremental protocol until voluntary exhaustion to find the v associated at the individual anaerobic threshold. V˙O2 kinetics (cardiodynamic, primary and slow component phases) and the aerobic and anaerobic energy contributions were assessed during the continuous exercises, which the former was studied for the beginning and second phase of exercise. Subjects showed similar time delay (TD) (mean = 11.5–14.3 s) and time constant (τ_p) (mean = 13.8–16.3 s) as a function of v, but reduced amplitude of the primary component for 97.5% (35.7 ± 7.3 mL.kg.min^-1) compared to 100 and 102.5%MLSS (41.0 ± 7.0 and 41.3 ± 5.4 mL.kg.min^-1, respectively), and τ_p decreased (mean = 9.6–10.8 s) during the second phase of exercise. Despite the slow component did not occur for all swimmers at all swim intensities, when observed it tended to increase as a function of v. Moreover, the total energy contribution was almost exclusively aerobic (98–99%) at 97.5, 100 and 102.5%MLSS. We suggest that well-trained endurance swimmers with a fast TD and τ_p values may be able to adjust faster the physiological requirements to minimize the amplitude of the slow component appearance, parameter associated with the fatigue delay and increase in exhaustion time during performance, however, these fast adjustments were not able to control the progressive fatigue occurred slightly above MLSS, and most of swimmers reached exhaustion before 30min swam.

Home Exercise Training in Children and Adolescents with Pulmonary Arterial Hypertension: A Pilot Study

Pulmonary arterial hypertension (PAH) is often associated with impaired exercise capacity. It has been shown that supervised training can improve exercise capacity in adult patients with PAH. The objective of this prospective study was to assess the feasibility of a home exercise training program in children with PAH. Nine children and adolescents (mean age 15.2 ± 3.8 years) with low-risk PAH (defined as mean pulmonary to systemic arterial pressure ratio <0.75; WHO functional class I and II) performed home-based exercise training for 16 weeks. Cardiopulmonary exercise testing and health-related quality of life was evaluated before and after 16 weeks of training. The amount of training at home and patients' well-being was supervised by periodical phone calls and online-questionnaires. Home exercise training was well tolerated in all patients, and no adverse events occurred. After 16 weeks of training, patients significantly improved their exercise capacity [treadmill running distance increased from 589.5 ± 153.9 to 747.9 ± 209.2 m (p = 0.036)]. Oxygen consumption at the anaerobic threshold increased from 1307.8 (±417) to 1406.4 (±418) ml (p = 0.028). Chronotropic index improved from 0.77 ± 0.12 to 0.82 ± 0.11 (p = 0.004) and was slightly related to the increase in running distance (r = 0.62; p = 0.07). Home exercise training is feasible in children and adolescents with low-risk PAH, and the preliminary results of this pilot study indicate beneficial effects. The observed increase in exercise capacity was accompanied by an improved chronotropic competence and increased oxygen consumption at the anaerobic threshold. Future research is needed to investigate the safety and efficacy of home exercise training in a larger population of children with PAH including also patients in WHO functional class III or IV.

Relationship between Anaerobic Power and Jumping of Selected Male Volleyball Players of Different Ages

The aim of the present study was to evaluate the anaerobic power of elite male volleyball players, using the Wingate Anaerobic Test to examine the relationship between anaerobic power and jumping performance. Athletes ( n = 56) and Nonathletes ( n = 53) were divided into three age groups: Adults (18–25 yr.), Juniors (15–16 yr.), and Youth (10–11 yr.). Measurements of height, body mass, vertical jump and Wingate scores indicated higher values for athletes. The specific training effects of anaerobic power were more pronounced at the age of 10–11 years than for Nonathletes. A significant correlation coefficient between peak power and vertical jump was found for Athletes ( r = .86) and for the total group ( r = .82). These results indicated that vertical jump may predict the maximal anaerobic power and could be used by coaches as a practical and easy-to-apply field screening test for evaluation in volleyball training.

Short-Term Effect of Physical Exercise at Lactate Threshold on Choice Reaction Time

The duration of the enhancement of choice reaction task efficiency by physical exercise at lactate threshold was studied. After healthy male students completed the exercise or nonexercise (control) period for 10 min., they performed a three-choice reaction task for 20 min. The mean heart rate during the choice reaction task after the exercise was higher than that after the control period ( p<.05). For average percentage of correct answers, there were no significant differences between the exercise and control conditions. The reaction time during the first 8 min. of the 20-min. choice reaction task after the exercise period was less than that after the control period and increased gradually thereafter. In conclusion, whereas the choice reaction time was improved by physical exercise at around lactate threshold, the positive effects were seen mainly in the early stages of the task.

Normobaric hyperoxia training in elite female hockey players

BACKGROUND

Supplemental oxygen use may offer recovery benefits to team sport athletes both in training and match play. A blinded independent measures study was used to investigate the effect of supplementary oxygen use during recovery from high-intensity exercise on performance.

METHODS

Fifteen female international hockey players underwent a 6 week running based training program with a 2:1 work to rest ratio. The subjects were split into 3 groups; normobaric hyperoxia (HXA), normoxia (NXA) and control (CTR). In between exercise sets HXA received 100% oxygen for 1 minute whilst NXA received a placebo in the same manner. CTR received no treatment and were not supervised. Maximal aerobic speed (MAS) was measured pre and post. Distance covered was measured along with peak heart rate (HRpeak), peak blood lactate concentration ([La-]peak) and rate of perceived exertion (RPE).

RESULTS

MAS improved in HXA, NXA and CTR. However, distance ran in training was not different between groups. There was a likely positive effect on HRpeak in HXA (lower in HXA). RPE and [La-]peak response was not different between groups.

CONCLUSIONS

Inhaling supplementary oxygen during recovery between high-intensity intervals did not improve physiological performance of high-level team sport players. The normobaric hyperoxia treatment had no effect on maximal aerobic (distance covered), metabolic ([La-]peak), and perception (RPE) parameters. It is not recommended as an ergogenic aid to training at sea level.

[Is there a disassociation of ventilatory and electromyographic thresholds in patients with heart disease during a graded cycling exercise?]

Exercise prescription was generally based on the determination of ventilatory thresholds (VT₁, VT₂) during cardiopulmonary exercise testing (CPX). Changes in surface electromyographic activity (EMG_th1, EMG_th2) were also related to VT₁ and VT₂ in healthy subjects.

OBJECTIVE

To observe the occurrence of EMGt_h1 and EMG_th2 and whether these events accompany VT₁ and VT₂ during CPX in cardiac patients (CP).

METHOD

Thirty-four CP (62.1±7.3years, 172.1±6.3cm, 81.3±15.3kg, BMI: 27.3±4.1) performed a cycle CPX at a 60-rpm cadence. VT₁ was determined as the breakpoint in the curve of carbon dioxide output against oxygen uptake plot (V-slope method). VT₂ was defined as the point at which the ratio of minute ventilation to carbon dioxide output starts to increase. The root mean square of electromyogram (rms-EMG) was on-line calculated from the real time bipolar surface electromyographic signals recorded from the vastus lateralis. EMG_th1 and EMG_th2 were defined as the first and the second breakpoints in the rms-EMG-power output relationship.

RESULTS

Peak values of oxygen uptake (16.3±4.6mL·min^-1·kg^-1) and heart rate (106.7±13.8bpm) were reached at 112.9±38.5w (PMT). VT₁ and VT₂ occurred at 71.1±25.9w (62.5±5.5% PMT) and 87.9±28.6w (78.0±5.1% PMT). All subjects presented two breakpoints in the rms-EMG curve, EMG_th1 at 68.0±24.7w and EMG_th2 at 88.5±30.1w, i.e. 60.0±7.6 and 78.6±5.0% of PMT. EMG_th1 occurred significantly before VT₁ (P=0.004, small effect size). No significant difference was observed between EMG_th2 and VT₂ (P=0.13, small effect size).

CONCLUSION

The EMG_th1 occurrence before VT₁ suggested a role of skeletal muscle conditioning on ventilatory responses, which should be taken into account in cardiac rehabilitation program prescription.

Acute inflammatory response to prolonged sculling in competitive male rowers

BACKGROUND

This study examined the effects of a prolonged low-intensity single scull rowing exercise on a complex of 12 different inflammatory cytokines in rowers.

METHODS

Twenty male rowers (19.0±2.9 yrs; 185.6±4.8 cm; 85.7±10.8 kg; 17.1±5.1% body fat; maximal oxygen consumption [VO2max]: 63.9±8.5 mL.min.-1kg-1) completed a rowing training session lasting about 2-h (distance: 21.4±1.8 km; heart rate [HR]: 139±8 beats.min-1; intensity: 79.9±3.6% of the anaerobic threshold) followed by a 30-min rest. Venous blood samples were collected before and after on-water rowing, and analyzed for blood white cell count (WBC), high sensitive C-reactive protein (hsCRP), and 12 inflammatory cytokines (interleukin [IL]-2, IL-4, IL-6, IL-8, IL-10, vascular endothelial growth factor, interferon-gamma, tumor necrosis factor-alpha, IL-1α, IL-1β, monocyte chemotactic protein-1 [MCP-1], epidermal growth factor).

RESULTS

Exercise induced significant (P<0.05) increment in WBC, hsCRP, IL-6, IL-10 and MCP-1 concentrations. The long-distance sculling intensity variables such as the average rating of perceived exertion, HR and blood lactate were correlated with changes in IL-8, IL-1α and IL-1β levels (r=0.47 to r=0.59; P<0.05). Maximal aerobic performance variables (VO2max and maximal aerobic power) were related to changes in IL-2, IL-4, IL-8 and IL-1β levels (r=-0.45 to r=-0.54; P<0.05).

CONCLUSIONS

Acute exercise-induced inflammatory reaction was reflected by a significant increase in serum IL-6, IL-10 and MCP-1 levels. Variance in exercise-induced increases in inflammatory markers in response to 2-h of endurance exercise was explained by aerobic performance and exercise intensity levels in competitive male rowers.

Determination of exercise training heart rate in patients on β-blockers after myocardial infarction

BACKGROUND

In patients with coronary artery disease, the target intensity-level of exercise training is usually based on a training heart rate that aims to be close to the upper level of metabolic aerobic exercise.

AIM

We intended to evaluate whether a training heart rate calculated with the Karvonen formula after a conventional exercise test is comparable with the heart rate at the anaerobic threshold in patients after myocardial infarction treated with beta-blockers and if not to propose a new formula.

METHODS AND RESULTS

In this multicenter prospective study, 115 consecutive beta-blocked patients recovering from myocardial infarction performed a cardiopulmonary exercise test to determine the anaerobic threshold. The training heart rate determined by the Karvonen formula was compared with the heart rate at the anaerobic threshold in a derivation sample (n=58) and a validation sample (n=57) of patients. The Karvonen training heart rate was significantly lower than the heart rate at the anaerobic threshold (91+/-5 versus 102+/-17 bpm, P<0.0001) in the first sample of patients and this difference was clinically relevant in 40% of patients. Thus, a 'modified Karvonen training heart rate', equal to 0.8xx(maximum heart rate-resting heart rate)+resting heart rate, was calculated by linear regression in the derivation sample and prospectively assessed in the validation sample. The modified Karvonen training heart rate was closer to the heart rate at the anaerobic threshold than the Karvonen training heart rate, and the difference between the modified Karvonen training heart rate and the heart rate at the anaerobic threshold was clinically relevant in only 5% of patients.

CONCLUSION

The Karvonen formula underestimates the heart rate at the anaerobic threshold in beta-blocked patients, which may lead to undertraining of patients with coronary artery disease; we propose another formula more adapted to these patients.

Does cumulating endurance training at the weekends impair training effectiveness?

BACKGROUND

Due to occupational restrictions many people's recreational endurance activities are confined to the weekends. We intended to clarify if cumulating the training load in such a way diminishes endurance gains.

DESIGN

We conducted a longitudinal study comparing training-induced changes within three independent samples.

METHODS

Thirty-eight healthy untrained participants (45+/-8 years, 80+/-18 kg; 172+/-9 cm) were stratified for endurance capacity and sex and randomly assigned to three groups: 'weekend warrior' (n=13, two sessions per week on consecutive days, 75 min each, intensity 90% of the anaerobic threshold; baseline lactate+1.5 mmol/l), regular training (n=12, five sessions per week, 30 min each, same intensity as weekend warrior), and control (n=13, no training). Training was conducted over 12 weeks and monitored by means of heart rate. Identical graded treadmill protocols before and after the training program served for exercise prescription and assessment of endurance effects.

RESULTS

VO2max improved similarly in weekend warrior (+3.4 ml/min per kg) and register training (+1.5 ml/min per kg; P=0.20 between groups). Compared with controls (-1.0 ml/min per kg) this effect was significant for weekend warriors (P<0.01) whereas there was only a tendency for the regular training group (P=0.10). In comparison with controls (mean decrease, 3 beats/min), the average heart rate during exercise decreased significantly by 11 beats/min (weekend warriors, P<0.01) and 9 beats/min (regular training, P<0.05). There was no significant difference, however, between the weekend warrior and regular training groups (P=0.99).

CONCLUSION

In a middle-aged population of healthy untrained subjects, cumulating the training load at the weekends does not lead to an impairment of endurance gains in comparison with a smoother training distribution.

The impact of neoadjuvant chemotherapy on cardiopulmonary physical fitness in gastro-oesophageal adenocarcinoma

Introduction Operable oesophagogastric adenocarcinoma management in the UK includes three cycles of neoadjuvant chemotherapy (NAC) followed by resection. Determination of oxygen uptake at the anaerobic threshold (AT) with cardiopulmonary exercise testing (CPET) is used to objectively measure cardiorespiratory reserve. Oxygen uptake at AT predicts perioperative risk, with low values associated with increased morbidity. Previous studies indicate NAC may have a detrimental impact on cardiorespiratory reserve. Methods CPET was completed by 30 patients before and after a standardised NAC protocol. The ventilatory AT was determined using the V-slope method, and the peak oxygen uptake and ventilatory equivalents for carbon dioxide measured. Median AT before and after chemotherapy was compared using a paired Student's t-test. Results Median oxygen uptake at AT pre- and post-NAC was 13.9±3.1 ml/kg/min and 11.5±2.0 ml/kg/min, respectively. The mean decrease was 2.4 ml/kg/min (95% confidence interval [CI] 1.3-3.85; p<0.001). Median peak oxygen delivery also decreased by 2.17 ml/kg/min (95% CI 1.02-3.84; p=0.001) after NAC. Ventilatory equivalents were unchanged. Conclusions This reduction in AT objectively quantifies a decrease in cardiorespiratory reserve after NAC. Patients with lower cardiorespiratory reserve have increased postoperative morbidity and mortality. Preventing this decrease in cardiorespiratory reserve during chemotherapy, or optimising the timing of surgical resection after recovery of AT, may allow perioperative risk-reduction.

[A NEW FIELD-TEST FOR THE ASSESSMENT OF THE HUMAN ANAEROBIC AND REPEATED SPRINTS CAPABILITY - RELIABILITY AND VALIDITY]

PURPOSE

To examine the reliability and validity of a newly developed anaerobic and repeated sprint (RST0 performance capability.

METHODS

A total of 35 untrained adolescent schoolchildren (age range 16-18 years) performed four tests: The newly developed 4 x 30 m RST, the Wingate Anaerobic Test (WAnT) and 200 m and 50 m sprint runs. The reliability of the test was assessed by comparing the test and retest performances of the test. The validity of the 4x30m RST was evaluated by computing the relationships among the various indices of the four studied anaerobic tests, and by comparing the effect of a well-defined anaerobic training program on the performance of the four anaerobic tests.

RESULTS

Strong and highly significant relationships were found between the mean (MP) and peak (PP) values of the 4x30 m RST (r = 0.88; p < 0.001), and between the MP of the RST and the two short sprints (50m and 200m) (r = 0.81 and 0.94, respectively; p < 0.011. Somewhat weaker, but still significant relationships were observed between the 4x30 RST and the WAnT indices (r's range = 0.56-0.64; p < 0.05). Such relationships suggest that the energetics of all four tests are closely related. Compared with baseline, the training group demonstrated similar and significant improvement in all four anaerobic tests. No such changes were detected for the control group.

CONCLUSIONS

The anaerobic system plays a dominant role in the performance of the new 4x30m RST. Furthermore, the new field test is highly reliable and was found to be valid for quantifying gross anaerobic and repeated sprints performance. Therefore, it can be used in pursuing athletes in a wide range of sports, as well as in some relevant occupations.

Are heart rate deflection point and peak velocity determined in the Université of Montréal Track Test valid to approximate aerobic parameters measured in the laboratory?

BACKGROUND

The aim of this study was to compare the respiratory compensation point (RCP) and maximal aerobic velocity (vVO2max) measured in the laboratory, respectively, with the heart rate deflection point (HRDP) and the peak velocity (PV) determined in the Université of Montréal Track Test (UMTT). Beside, we investigated the relationship of these parameters with endurance performance.

METHODS

Eighteen long distance runners randomly performed (in different days) two incremental exercise tests (laboratory and UMTT). RCP and vVO2max were identified in a treadmill test. The HRDP was identified using the Dmax method, while the PV was identified as the velocity of the last complete stage (PVc) and the time-corrected velocity of the last incomplete stage (PVi). Endurance performance was the reported 10-km race time from the closest race to the test visits.

RESULTS

RCP heart rate (176±14 bpm) was not significantly different from HRDP (173±10 bpm). The agreement was reasonable [bias: 4 bpm (95% limit of agreement: -16 to 24 bpm)]. vVO2max (18.0±2.1 km.h-1) was not significantly different from PVi (17.6±2.1 km.h-1), but was significantly higher than PVc (17.3±2.0 km.h-1). The agreement between vVO2max and PVi was acceptable [0.4 km.h-1 (-1.6 to 2.4 km.h-1)]. Endurance performance correlations (2212±277 s) with HRDP velocity (r=-0.75) and PVi (r=-0.83) tended to be lower than with RCP velocity (r=-0.91) and vVO2max (r=-0.85).

CONCLUSIONS

It is possible to estimate with reasonable accuracy the vVO2max using the UMTT. However, care must be taken to use the HRDP identified through the UMTT to prescribe training intensities.

The relationship between the heart rate deflection point test and maximal lactate steady state

BACKGROUND

The aim of this study was to investigate the use of the Heart Rate Deflection Point Test (HRDP) in the determination of the velocity at the Maximal Lactate Steady State (MLSS).

METHODS

Fifteen untrained male participants took part in a 3000-m running performance on a 400-m track. The volunteers performed an incremental test for HRDP determination. The third test was constant velocity, which lasted around 30 minutes and was based around HRDP for MLSS determination.

RESULTS

Performance velocity at HRDP was strongly correlated with the MLSS running velocity (r=0.84; R2=0.71; P<0.0001). HRDP running velocity (mean±SD 9.0±1.3-km.h-1) was not significantly different (P>0.05) from MLSS velocity (9.3±1.3km.h-1). A high agreement was observed between methods (Bland and Altman analysis) with a mean error of 0.47 km.h-1.

CONCLUSIONS

We can conclude that the HRDP was able to predict MLSS velocity.

Relationship between motor corticospinal excitability and ventilatory response during intense exercise

PURPOSE

Effort sense has been suggested to be involved in the hyperventilatory response during intense exercise (IE). However, the mechanism by which effort sense induces an increase in ventilation during IE has not been fully elucidated. The aim of this study was to determine the relationship between effort-mediated ventilatory response and corticospinal excitability of lower limb muscle during IE.

METHODS

Eight subjects performed 3 min of cycling exercise at 75-85 % of maximum workload twice (IE1st and IE2nd). IE2nd was performed after 60 min of resting recovery following 45 min of submaximal cycling exercise at the workload corresponding to ventilatory threshold. Vastus lateralis muscle response to transcranial magnetic stimulation of the motor cortex (motor evoked potentials, MEPs), effort sense of legs (ESL, Borg 0-10 scale), and ventilatory response were measured during the two IEs.

RESULTS

The slope of ventilation (l/min) against CO2 output (l/min) during IE2nd (28.0 ± 5.6) was significantly greater than that (25.1 ± 5.5) during IE1st. Mean ESL during IE was significantly higher in IE2nd (5.25 ± 0.89) than in IE1st (4.67 ± 0.62). Mean MEP (normalized to maximal M-wave) during IE was significantly lower in IE2nd (66 ± 22 %) than in IE1st (77 ± 24 %). The difference in mean ESL between the two IEs was significantly (p < 0.05, r = -0.82) correlated with the difference in mean MEP between the two IEs.

CONCLUSIONS

The findings suggest that effort-mediated hyperventilatory response to IE may be associated with a decrease in corticospinal excitability of exercising muscle.

Individual anaerobic threshold estimates maximal lactate steady state in temperate and hot climate

BACKGROUND

The aim of the present study was to compare the power output at the maximal lactate steady state (MLSS) with the power output at the individual anaerobic threshold (IAT) and at the onset of blood lactate accumulation (OBLA) in both temperate (TEMP) (22 °C) and hot (HOT) (40 °C) climates.

METHODS

Eight young active male (23.9±2.4 yr, 75.9±7.3 kg and 47.8±4.9 mL/kg/min) were evaluated on a cycle ergometer and performed a progressive exercise test until fatigue to determine the IAT and OBLA and two to five 30-min exercise tests at constant intensities for determine MLSS at both temperatures. An ANOVA with repeated measures and Dunnett's post-hoc test was performed to compare results of IAT and OBLA to the variables at the MLSS in both climates with MLSS being considered as the standard.

RESULTS

At TEMP there was no difference between the power output at MLSS and IAT (180±11 W and 182±13 W, respectively), however, the intensity of the OBLA (154±11 W) was lower than MLSS (P<0.05). At HOT there was no difference between the power output at MLSS, IAT, and OBLA (148±11 W, 155±12 W and 144±11 W, respectively).

CONCLUSIONS

These results showed that IAT is sensitive enough to estimate MLSS in both TEMP and HOT climate.

Do Male And Female Cyclists' Cortical Activity Differ Before and During Cycling Exercise?

Although men and women are suggested to vary in resistance to fatigue, possible sex difference in its central component have rarely been investigated via electroencephalography (EEG). Therefore, we examined differences in cortical activity between male and female cyclists (n = 26) during cycling exercise. Participants performed an incremental test to derive the anaerobic threshold from the lactate power curve. In addition, cyclists' cortical activity was recorded with EEG before and during cycling exercise. Whereas women showed higher frontal alpha and beta activity at rest, no sex-specific differences of relative EEG spectral power occurred during cycling at higher intensity. Women and men's brains respond similarly during submaximal cycling, as both sexes show an inverted U-shaped curve of alpha power. Therefore, sex differences observable at rest vanish after the onset of exercise.

Post-analysis methods for lactate threshold depend on training intensity and aerobic capacity in runners. An experimental laboratory study

CONTEXT AND OBJECTIVE

This study aimed to evaluate different mathematical post-analysis methods of determining lactate threshold in highly and lowly trained endurance runners.

DESIGN AND SETTING

Experimental laboratory study, in a tertiary-level public university hospital.

METHOD

Twenty-seven male endurance runners were divided into two training load groups: lowly trained (frequency < 4 times per week, < 6 consecutive months, training velocity ≥ 5.0 min/km) and highly trained (frequency ≥ 4 times per week, ≥ 6 consecutive months, training velocity < 5.0 min/km). The subjects performed an incremental treadmill protocol, with 1 km/h increases at each subsequent 4-minute stage. -Fingerprint -blood-lactate analysis was performed at the end of each stage. The lactate threshold (i.e. the running velocity at which blood lactate levels began to exponentially increase) was measured using three different methods: increase in blood lactate of 1 mmol/l at stages (DT1), absolute 4 mmol/l blood lactate concentration (4 mmol), and the semi-log method (semi-log). ANOVA was used to compare different lactate threshold methods and training groups.

RESULTS

Highly trained athletes showed significantly greater lactate thresholds than lowly trained runners, regardless of the calculation method used. When all the subject data were combined, DT1 and semi-log were not different, while 4 mmol was significantly lower than the other two methods. These same trends were observed when comparing lactate threshold methods in the lowly trained group. However, 4 mmol was only significantly lower than DT1 in the highly trained group.

CONCLUSION

The 4 mmol protocol did not show lactate threshold measurements comparable with DT1 and semi-log protocols among lowly trained athletes.

Aerobic training program for the enhancements of HR and VO2 off-kinetics in elite judo athletes

AIM

The purpose of this study was to investigate the physiologic and performance changes with the addition of high-intensity interval training (HIIT) to a traditional judo programme.

METHODS

Nine elite judokas (6 males and 3 females; age: 20±4 yrs; body mass: 69±2 kg; height: 172±7 cm; judo practice time: 13±6 yrs; weekly training volume: 13±5 hours, mean±SD) were recruited to perform a 12-week specific aerobic training program, which consisted of 2 session/week of 30-min continuous run at 60% at Vmax and one session/week of high-intensity interval training 15x1-min at 90% of Vmax with 1 min of active recovery at 60% of Vmax. Before and after the intervention all athletes performed a graded maximal exercise Test to measure maximal oxygen consumption (V̇O2max), ventilatory threshold (VT), maximal velocity (Vmax), heart rate (HR) and V̇O2 off kinetics. V̇O2 and HR recovery kinetics were evaluated on a breath-by-breath basis using a single component exponential function. Anaerobic capacity during specific movements was assessed with the Special judo fitness Test (SJFT).

RESULTS

The maximal speed reached during the maximal aerobic power test significantly increaseed (P=0.04), but V̇O2max did not change. τ of HR and of V̇O2 recovery significantly decreased by 17.3% (P=0.04) and 22.0% (P<0.01), respectively. VT increased (6.6%; P=0.03) and the SJFT Index improved (12%; P<0.001) 12% after training.

CONCLUSION

The aerobic fitness of elite judokas may be improved by adding aerobic routines to the normal training enhancing the recovery capacity.

Somatotype and stress hormone levels in young soccer players

AIM

The relationship between somatotype and cortisol and adrenocorticotropic (ACTH) hormone concentrations at rest or after exercise in adolescent soccer players at different time points throughout a soccer season is not understood. Therefore, the aim of this study was to examine the relationship between somatotype and cortisol and ACTH concentrations at rest and after exercise in adolescent soccer players at different time points during a soccer season.

METHODS

During the first 4 months of the soccer season, 47 soccer players (between 15-17 years of age) were tested at three different time points including at baseline, after 6 weeks, and at the end of 4 months. Testing included anaerobic threshold (AnT, km/h) and maximal speed of running (Max, km/h) were measured with Conconi protocol on treadmill. Before and after a maximal exercise Test, plasma levels of cortisol (ug/dL) and ACTH (pg/ml) were assessed by chemiluminometry enzyme amplificated method. Heath-Carter anthropometric somatotype model was used to determine 13 elements of somatotype. Descriptive statistics and multiple regression were used for statistical analysis (P<0.05).

RESULTS

Body composition and AnT were not significantly different between each time point of testing. The mesomorph-ectomorph (N.=21), balanced mesomorph (N.=8) and balanced ectomorph (N.=7) were the most frequent somatotypes. There were significant decrements of cortisol plasma levels (at rest 33.4%; after test 27.46%), with insignificant changes of ACTH plasma levels, after 6 weeks of preparation phase and after finishing of half season, at rest and after maximal treadmill test. There were significant correlation between ACTH levels at rest (R=0.44; P<0.01) and some somatotypes (mesomorph endomorph, central and balanced endomorph) and ACTH levels after maximal exercise test (R=0.36; P<0.05) and balanced ectomorph and endomorph mesomorph. There were significant correlation between cortisol levels after maximal exercise test at the beginning of training process (R=0.59; P<0.01) and some somatotypes (mesomorph ectomorph, mesomorph endomorph, balanced endomorph and endomorph mesomorph) and after the finishing of training process (R=0.62; P<0.01) and some somatotypes (central, balanced ectomorph and mesomorph ectomorph).

CONCLUSION

The significant decreases of cortisol plasma levels during soccer training process could indicate a stagnation of training process, accordingly with insignificant changes of AnT. The significant correlations of some somatotypes with stress hormonal responses could only suggest that the somatotype characteristics of young soccer players could be of interest in process of selection and planning of soccer training process with an essential need for more studies.

Relationship between heart rate deflection point determined by Dmax method and 10-km running performance in endurance recreationally-trained female runners

AIM

The aim of this paper was to verify the relationship between the speed at heart rate deflection point based on Dmax method (sHRDPDmax) with 10-km running performance and the speed at lactate threshold calculated with Dmax method (sLTDmax) in endurance recreationally-trained female runners. We also aim to examine the influence of exponential-plus-constant and third-order polynomial regression models and the influence of the heart rate points (model with initial HR points above 140 b·min(-1) versus model with all HR points) on the determination of the sHRDPDmax.

METHODS

Thirteen endurance recreationally-trained female runners were recruited. Participants performed a discontinuous incremental exercise tests initiating at 7 km·h(-1) with 1 km·h(-1) increments each 3 min to determine sHRDPDmax and sLTDmax according to two adjustments: 1) exponential-plus-constant regression model (sHRDPexp and sLTexp); 2) third-order polynomial regression model (sHRDPpol and sLTpol). The sHRDPDmax was also calculated based on HR points above 140 b·min(-1) (sHRDPexp>140 and sHRDPpol>140). Each participant performed a 10-km running performance (s10km).

RESULTS

Only the sHRDPexp and sHRDPexp>140 correlated with s10km (sHRDPexp, r=0.87; sHRDPexp>140, r=0.76) and showed higher correlations than the sHRDPpol and sHRDPpol>140 with sLTDmax. The sHRDPexp presented higher correlation with sLTexp than sHRDPexp>140, however sHRDPexp>140 better correlated with sLTpol than sHRDPexp. Furthermore, sHRDPpol>140 demonstrated higher correlations with sLTexp and sLTpol than sHRDPpol.

CONCLUSION

The determination of sHRDPDmax according to different initial HR point and its correlation with sLTDmax is influenced by the regression model. Further, only sHRDPexp and sHRDPexp>140 were predictors of endurance performance. However, despite the high correlations, the deflection point very often occurred around the midpoint between initial and final speeds during the incremental test suggesting that the exponential-plus-constant may not be an appropriate regression curve.