End criteria for reaching maximal oxygen uptake must be strict and adjusted to sex and age: a cross-sectional study

Is there really a proportional relationship between VO2max and body weight? A review article

Maximum oxygen uptake (VO_2max) is a “gold standard” in aerobic capacity assessment, playing a vital role in various fields. However, ratio scaling (VO2maxbw), the present method used to express relative VO_2max, should be suspected due to its theoretical deficiencies. Therefore, the aim of the study was to revise the quantitative relationship between VO_2max and body weight (bw). Dimensional analysis was utilized to deduce their theoretical relationship, while linear or nonlinear regression analysis based on four mathematical models (ratio scaling, linear function, simple allometric model and full allometric model) were utilized in statistics analysis to verify the theoretical relationship. Besides, to investigate the effect of ratio scaling on removing body weight, Pearson correlation coefficient was used to analyze the correlation between VO2maxbw and bw. All the relevant data were collected from published references. Dimensional analysis suggested VO_2max be proportional to bw23. Statistics analysis displayed that four mathematical expressions were VO_2max = 0.047bw (p<0.01, R² = 0.68), VO_2max = 0.036bw+0.71 (p<0.01, R² = 0.76), VO_2max = 0.10bw^0.82 (p<0.01, R² = 0.93) and VO_2max = 0.23bw^0.66–0.48 (p<0.01, R² = 0.81) respectively. Pearson correlation coefficient showed a significant moderately negative relation between VO2maxbw and bw (r = -0.42, p<0.01), while there was no correlation between VO2maxbw0.82 and bw (r = 0.066, p = 0.41). Although statistics analysis did not fully verify the theoretical result, both dimensional and statistics analysis suggested ratio scaling distort the relationship and power function be more appropriate to describe the relationship. Additionally, we hypothesized that lean mass, rather than body weight, plays a more essential role in eliminating the gap between theoretical and experimental b values, and is more appropriate to standardize VO_2max, future studies can focus more on it.

Effect of Wearing Surgical Face Masks During Exercise: Does Intensity Matter?

Face masks are widely recommended as means of controlling the coronavirus disease outbreak. This study aimed to examine the physiological and perceptual responses of wearing surgical face masks while exercising at different intensities. Thirteen healthy young adults (mean age, 21.9 ± 1.4 years) conducted randomized crossover trials with or without a surgical face mask. In each trial, participants completed an incremental treadmill protocol, with three 6-min stages (light, moderate, and vigorous at 25, 50, and 75% maximal oxygen uptake, respectively). Physiological outcomes (heart rate, blood lactate, and oxygen saturation level), perceived exertion and discomfort feeling were assessed. No significant differences were observed in physiological outcomes with or without masks at different exercise intensities (p > 0.05). However, the rating of perceived exertion (RPE) was significantly higher when exercising vigorously (mask: 15.5 ± 1.5 vs. no-mask: 14.2 ± 2.1, p < 0.05). Participants wearing masks reported marked discomfort, such as feeling hot, humid, and breathing resistance. Although face mask-wearing during exercise may not have detrimental effects on major physiological parameters, it can increase perceived exertion level and discomfort when the exercise intensity exceeds a certain threshold. Therefore, healthcare professionals should cautiously evaluate each person’s ability to exercise while wearing a mask and tailor their prescription accordingly.

Life-long sports engagement enhances adult erythrocyte adenylate energetics

Regular physical activity reduces age-related metabolic and functional decline. The energy stored in adenine nucleotides (ATP, ADP, and AMP) is essential to enable multiple vital functions of erythrocytes and body tissues. Our study aimed to predict the rate of age-related changes in erythrocyte adenylate energetics in athletes and untrained controls. The erythrocyte concentration of adenylates was measured in 68 elite endurance runners (EN, 20–81 years), 58 elite sprinters (SP, 21–90 years), and 62 untrained individuals (CO, 20–68 years). Resting concentrations of ATP, total adenine nucleotide pool, and ADP/AMP ratio were lowest in the CO group and highest in the SP group. The concentration of erythrocyte ADP and AMP was lowest in the EN group and highest in the CO group. In all studied groups, we found a significant increase in the concentration of most erythrocyte adenylate metabolites with age. For ADP and AMP, the trend was also significant but decreasing. Our study strongly suggests that lifelong sports and physical activity participation supports erythrocyte energetics preservation. Although the direction and the predicted rates of change are similar regardless of the training status, the concentrations of particular metabolites are more advantageous in highly trained athletes than in less active controls. Of the two analyzed types of physical training, sprint-oriented training seems to be more efficient in enhancing erythrocyte metabolism throughout adulthood and old age than endurance training.

Professional cyclists have lower levels of bone markers than amateurs. Is there a risk of osteoporosis in cyclist?

Currently, there is a greater number of amateurs that practice cycling. However, there is no clear evidence regarding bone health in amateur cyclists compared to professional cyclists, as the latter has shown to have lower bone mineral content and density. Therefore, the aim of this study was to identify the differences in bone variables between professional (PRO) and amateur (AMA) road cyclists, and to see if these differences were related to differences in cycling performance. A parallel trial was carried out with 15 AMA and 10 PRO cyclists. All cyclists visited the laboratory twice: 1) in a fasted state, body composition measured by dual-energy X-ray absorptiometry (DXA) and 2) physiological variables measured using an incremental test until exhaustion. Significantly lower values were found in bone mineral density, bone mineral content and fat free mass in PRO compared to AMA (p < 0.05). In addition, significantly higher power was produced in ventilatory thresholds 1 and 2 (VT1 and VT2) and VO_2MAX in PRO compared to AMA (p < 0.05). Overall, PRO cyclists had lower values in bone health and muscle mass but better results in performance compared to AMA.

Impacts of different intensities of exercise on inflammation and hypoxia markers in low altitude

Background

This study aims to determine and compare the effects of exercise modalities with different intensities on the secretion of key inflammation and hypoxia markers in amateur athletes.

Methods

Twenty-three athletes with a mean age of 20.1 years, living at low altitude (1850 m) participated in this study. The participants' maximal oxygen consumption values (VO₂ max) were determined with an incremental cycle exercise test as 54.15 ± 6.14 mL kg min⁻¹. Athletes performed four protocols: at rest, 50% VO₂ max, 75% VO₂ max and 100% VO₂ max (until exhaustion) with one-week intervals. 50% VO₂ max, 75% VO₂ max sessions were performed continuously for 30 min on a bicycle ergometer and 100% VO₂ max session was performed by cycling until exhaustion. Blood samples were obtained at rest and immediately after each exercise session. Serum tumor necrosis factor alpha (TNF-α), C-reactive protein (CRP), interleukin-10 (IL-10), and hypoxia inducible factor-1 alpha (HIF-1α) levels were measured.

Results

There were significant differences in serum TNF-α levels in 75% VO₂ max and 100% VO₂ max sessions (489.03 ± 368.37 and 472.70 ± 365.21 ng/L, respectively) compared to rest conditions (331.65 ± 293.52 ng/L). Serum CRP levels of 50% VO₂ max and 75% VO₂ max sessions (1.19 ± 0.50; 1.07 ± 0.52 mg/L) were significantly higher than the rest condition (0.74 ± 0.35 mg/L). There were significant differences in serum IL-10 levels of rest condition and 50% VO₂ max; 50% VO₂ max, and 100% VO₂ max sessions (328.09 ± 128.87; 446.36 ± 142.84; 347.44 ± 135.69; 324.88 ± 168.06 pg/mL). Serum HIF-1α levels were significantly higher in 75% VO2 max session compared to rest (1.26 ± 0.16; 1.08 ± 0.19 ng/mL) (P < 0.05 for all comparisons).

Conclusions

Both inflammatory and anti-inflammatory pathway is induced on different exercise intensities. Exercise protocols performed until exhaustion may lead to activation of inflammatory pathways and hypoxia-induced damage.

Performance Profile among Age Categories in Young Cyclists

Simple Summary

Overall, adolescence brings upon many bodily changes that modify physical capacities. To better understand these physiological changes and the characteristics of each stage of adolescent development in youth cycling, it is necessary to describe and compare cyclists that pertain to lower categories. Parameters such as maximum oxygen uptake, fat oxidation capacity, functional power threshold, and ventilatory thresholds are decisive predictors of performance in future stages. The aim of this study was to evaluate and compare the physiological profile of different road cyclist age categories (Youth, Junior, and Under-23) to obtain the performance requirements. The results suggest major differences, with the Youth group showing clear changes in all metabolic zones except in fat oxidation. The Youth group physiological profile is clearly different from the other age categories. The present results suggest that the Juniors’ qualities are closer to adult performance, however, little is known about sports performance indicators in adolescent cyclists.

Abstract

Endurance profile assessment is of major interest to evaluate the cyclist’s performance potential. In this regard, maximal oxygen uptake and functional threshold power are useful functional parameters to determine metabolic training zones (ventilatory threshold). The aim of this study was to evaluate and compare the physiological profile of different road cyclist age categories (Youth, Junior, and Under-23) to obtain the performance requirements. Sixty-one competitive road cyclists (15–22 years) performed a maximal incremental test on a bike in order to determine functional parameters (maximal fat oxidation zone, ventilatory thresholds, maximal oxygen uptake, and functional threshold power) and metabolic training zones. The results suggest major differences, with the Youth group showing clear changes in all metabolic zones except in fat oxidation. The main differences between Under-23 vs. Junior groups were observed in maximal relative power output (Under-23: 6.70 W·Kg⁻¹; Junior: 6.17 W·Kg⁻¹) and relative functional threshold power (Under-23: 4.91 W·Kg⁻¹; Junior: 4.48 W·Kg⁻¹). The Youth group physiological profile is clearly different to the other age categories. Some parameters normalized to body weight (maximal oxygen consumption, load and functional threshold power) could be interesting to predict a sporting career during the Junior and Under-23 stages.

Validity of the 6-Minute Walk Test and YMCA Submaximal Cycle Test During Midpregnancy

Tinius, RA, Blankenship, M, Maples, JM, Pitts, BC, Furgal, K, Norris, ES, Hoover, DL, Olenick, A, Lambert, J, and Cade, WT. Validity of the 6-minute walk test and Young Men's Christian Association (YMCA) submaximal cycle test during midpregnancy. J Strength Cond Res 35(11): 3236-3242, 2021-Submaximal exercise testing can be a feasible alternative to maximal testing within special populations to safely predict fitness levels; however, submaximal exercise testing has not been well-validated for use during pregnancy. The purpose of this study was to determine the concurrent validity of the 6-minute walk test (6MWT) and the YMCA submaximal cycle test (YMCAT) to predict V̇o2max in physically active women during midpregnancy. Thirty-seven (n = 37) pregnant women (22.1 ± 1.4 weeks' gestation) and 10 (n = 10) nonpregnant women participated in the study. Subjects completed a graded maximal treadmill test at 1 visit to measure maximal oxygen consumption (V̇o2max), and then subjects completed the 6MWT and YMCAT in randomized order during a separate visit. The predicted V̇o2max from each submaximal test were compared with the measured V̇o2max from the treadmill test to assess the validity of these tests during pregnancy. Among pregnant women, predicted V̇o2max from the YMCAT was not correlated to the measured V̇o2max (r = 0.14, p = 0.42), and the predicted V̇o2max from the 6MWT was only moderately correlated (r = 0.40, p = 0.016) to the measured V̇o2max. Among nonpregnant women, the predicted V̇o2max values from both the YMCAT and the 6MWT had strong correlations with the measured V̇o2max values (YMCAT: r = 0.71, p = 0.02; 6MWT: r = 0.80, p = 0.006). Neither test demonstrated concurrent validity among the pregnant sample. The main finding is that the YMCAT is not a valid method to estimate V̇o2max during midpregnancy (likely due to physiological changes in heart rate [HR] during pregnancy). The 6MWT has potential to be used clinically for estimating fitness as actual and predicted values did positively correlate, and it is not dependent on HR responses to exercise. However, if a precise measure of fitness is needed, then neither test appears to have strong validity for use during midpregnancy.

Complex lifestyle intervention among inactive older adults with elevated cardiovascular disease risk and obesity: a mixed-method, single-arm feasibility study for RESTART-a randomized controlled trial

Background

Physical inactivity and obesity are global public health challenges. Older adults are important to target for prevention and management of disease and chronic conditions. However, many individuals struggle with maintaining increased physical activity (PA) and improved diet. This feasibility study provides the foundation for the RESTART trial, a randomized controlled trial (RCT) to test a complex intervention to facilitate favourable lifestyle changes older adults can sustain. The primary objective of this study was to investigate study feasibility (recruitment, adherence, side-effects, and logistics) using an interdisciplinary approach.

Methods

This 1-year prospective mixed-method single-arm feasibility study was conducted in Tromsø, Norway, from September 2017. We invited by mail randomly selected participants from the seventh survey of the Tromsø Study (2015–2016) aged 55–75 years with sedentary lifestyle, obesity, and elevated cardiovascular risk. Participants attended a 6-month complex lifestyle intervention program, comprising instructor-led high-intensive exercise and nutritionist- and psychologist-led counselling, followed by a 6-month follow-up. All participants used a Polar activity tracker for daily activity monitoring during the intervention. Participants were interviewed three times throughout the study. Primary outcome was study feasibility measures.

Results

We invited potential participants (n=75) by mail of which 27 % (n=20) agreed to participate. Telephone screening excluded four participants, and altogether 16 participants completed baseline screening. The intervention and test procedures of primary and secondary outcomes were feasible and acceptable for the participants. There were no exercise-induced injuries, indicating that the intervention program is safe. Participants experienced that the dietary and psychological counselling were delivered too early in the intervention and in too close proximity to the start of the exercise program. Minor logistic improvements were implemented throughout the intervention period.

Conclusion

This study indicates that it is feasible to conduct a full-scale RCT of a multi-component randomized intervention trial, based on the model of the present study. No dropouts due to exercise-induced injury indicates that the exercises were safe. While minor improvements in logistics were implemented during the intervention, we will improve recruitment and adherence strategies, rearrange schedule of intervention contents (exercise, diet, and psychology), as well as improve the content of the dietary and behavioural counselling to maximize outcome effects in the RESTART protocol.

Trial registration

ClinicalTrials.gov Identifier: NCT03807323 Registered 16 January 2019 – retrospectively registered.

Feasibility, Methodology, and Interpretation of Broad-Scale Assessment of Cardiorespiratory Fitness in a Large Community-Based Sample

Cardiorespiratory fitness (CRF) is intricately related to health status. The optimal approach for CRF quantification is through assessment of peak oxygen uptake (VO₂), but such measurements have been largely confined to small referral populations. Here we describe protocols and methodological considerations for peak VO₂ assessment and determination of volitional effort in a large community-based sample. Maximum incremental ramp cycle ergometry cardiopulmonary exercise testing (CPET) was performed by Framingham Heart Study participants at a routine study visit (2016 to 2019). Of 3,486 individuals presenting for a multicomponent study visit, 3,116 (89%) completed CPET. The sample was middle-aged (54 ± 9 years), with 53% women, body mass index 28.3 ± 5.6 kg/m², 48% with hypertension, 6% smokers, and 8% with diabetes. Exercise duration was 12.0 ± 2.1 minutes (limits 3.7to20.5). No major cardiovascular events occurred. A total of 98%, 96%, 90%, 76%, and 57% of the sample reached peak respiratory exchange ratio (RER) values of ≥1.0, ≥1.05, ≥1.10, ≥1.15, and ≥1.20, respectively (mean peak RER = 1.21 ± 0.10). With rising peak RER values up to ≈1.10, steep changes were observed for percent predicted peak VO₂, VO₂ at the ventilatory threshold/peak VO₂, heart rate response, and Borg (subjective dyspnea) scores. More shallow changes for effort dependent CPET variables were observed with higher achieved RER values. In conclusion, measurement of peak VO₂ is feasible and safe in a large sample of middle-aged, community-dwelling individuals with heterogeneous cardiovascular risk profiles. Peak RER ≥1.10 was achievable by the majority of middle-aged adults and RER values beyond this threshold did not necessarily correspond to higher peak VO₂ values.

Blocking endogenous IL-6 impairs mobilization of free fatty acids during rest and exercise in lean and obese men

Lack of interleukin-6 (IL-6) leads to expansion of adipose tissue mass in rodents and humans. The exact underlying mechanisms have not been identified. In this placebo-controlled, non-randomized, participant-blinded crossover study, we use the IL-6 receptor antibody tocilizumab to investigate the role of endogenous IL-6 in regulating systemic energy metabolism at rest and during exercise and recovery in lean and obese men using tracer dilution methodology. Tocilizumab reduces fatty acid appearance in the circulation under all conditions in lean and obese individuals, whereas lipolysis (the rate of glycerol appearance into the circulation) is mostly unaffected. The fact that fatty acid oxidation is unaffected by IL-6 receptor blockade suggests increased re-esterification of fatty acids. Glucose kinetics are unaffected. We find that blocking endogenous IL-6 signaling with tocilizumab impairs fat mobilization, which may contribute to expansion of adipose tissue mass and, thus, affect the health of individuals undergoing anti-IL-6 therapy (Clinicaltrials.gov: NCT03967691).

The relationship between relative aerobic load, energy cost, and speed of walking in individuals post-stroke

BACKGROUND

Individuals post-stroke walk slower than their able-bodied peers, which limits participation. This might be attributed to neurological impairments, but could also be caused by a mismatch between aerobic capacity and aerobic load of walking leading to an unsustainable relative aerobic load at most economic speed and preference for a lower walking speed.

RESEARCH QUESTION

What is the impact of aerobic capacity and aerobic load of walking on walking ability post-stroke?

METHODS

Forty individuals post-stroke (more impaired N = 21; preferred walking speed (PWS)<0.8 m/s, less impaired N = 19), and 15 able-bodied individuals performed five, 5-minute treadmill walking trials at 70 %, 85 %, 100 %, 115 % and 130 % PWS. Energy expenditure (mlO₂/kg/min) and energy cost (mlO₂/kg/m) were derived from oxygen uptake (V˙O₂). Relative load was defined as energy expenditure divided by peak aerobic capacity (%V˙O₂peak) and by V˙O₂ at ventilatory threshold (%V˙O₂-VT). Relative load and energy cost at PWS were compared with one-way ANOVA's. The effect of speed on these parameters was modeled with Generalized Estimating Equations.

RESULTS

Both more and less impaired individuals post-stroke showed lower PWS than able-bodied controls (0.44 [0.19-0.76] and 1.04 [0.81-1.43] vs 1.36 [0.89-1.53] m/s) and higher relative load at PWS (50.2 ± 14.4 and 51.7 ± 16.8 vs 36.2 ± 7.6 %V˙O₂peak and 101.9 ± 20.5 and 97.0 ± 27.3 vs 64.9 ± 13.8 %V˙O₂-VT). Energy cost at PWS of more impaired (0.30 [.19-1.03] mlO₂/kg/m) was higher than less-impaired (0.19[0.10-0.24] mlO₂/kg/m) and able-bodied (0.15 [0.13-0.18] mlO₂/kg/m). For post-stroke individuals, increasing walking speed above PWS decreased energy cost, but resulted in a relative load above endurance threshold.

SIGNIFICANCE

Individuals post-stroke seem to reduce walking speed to prevent unsustainably high relative aerobic loads at the expense of reduced economy. When aiming to improve walking ability post-stroke, it is important to consider training aerobic capacity.

Association of Physical Activity With Maximal and Submaximal Tests of Exercise Capacity in Middle- and Older-Aged Adults

Although physical activity (PA) is an important determinant of exercise capacity, the association between these constructs is modest. The authors investigated the associations of self-reported and objectively measured PA with maximal and submaximal tests of exercise capacity. Participants aged ≥40 years (N = 413; 49.6% female) completed a PA questionnaire, wore a uniaxial accelerometer (5.2 ± 1.1 days), and performed maximal (cardiopulmonary exercise test [CPET]) and submaximal (long-distance corridor walk) tests with indirect calorimetry (oxygen consumption, V˙O2). Linear regression models were fitted to assess the variation in exercise capacity explained (partial eta squared, η2) by PA variables. Accelerometer-measured vigorous (η2 = 22% female; η2 = 16% male) and total PA (η2 = 17% female; η2 = 13% male) explained the most variance in CPET V˙O2 (p < .001). All η2 values were lower for long-distance corridor walk V˙O2 (η2 ≤ 11%). Age contributed more to CPET V˙O2 than any PA variable in males (η2 = 32%), but not in females (η2 = 19%). Vigorous and total PA play important roles in CPET V˙O2 in mid to late life.

Sex differences in adaptation to intermittent post-exercise sauna bathing in trained middle-distance runners

Background

The purpose of this study was to investigate the effect of sex on the efficacy of intermittent post-exercise sauna bathing to induce heat acclimation and improve markers of temperate exercise performance in trained athletes.

Methods

Twenty-six trained runners (16 female; mean ± SD, age 19 ± 1 years, V̇O_2max F: 52.6 ± 6.9 mL⋅kg⁻¹⋅min⁻¹, M: 64.6 ± 2.4 mL⋅kg⁻¹⋅min⁻¹) performed a running heat tolerance test (30 min, 9 km⋅h⁻¹/2% gradient, 40 °C/40%RH; HTT) and temperate (18 °C) exercise tests (maximal aerobic capacity [V̇O_2max] and lactate profile) pre and post 3 weeks of normal exercise training plus 29 ± 1 min post-exercise sauna bathing (101–108 °C) 3 ± 1 times per week.

Results

Females and males exhibited similar reductions (interactions p > 0.05) in peak rectal temperature (− 0.3 °C; p < 0.001), skin temperature (− 0.9 °C; p < 0.001) and heart rate (− 9 beats·min⁻¹; p = 0.001) during the HTT at post- vs pre-intervention. Only females exhibited an increase in active sweat glands on the forearm (measured via modified iodine technique; F: + 57%, p < 0.001; M: + 1%, p = 0.47). Conversely, only males increased forearm blood flow (measured via venous occlusion plethysmography; F: + 31%, p = 0.61; M: + 123%; p < 0.001). Females and males showed similar (interactions p > 0.05) improvements in V̇O_2max (+ 5%; p = 0.02) and running speed at 4 mmol·L⁻¹ blood lactate concentration (+ 0.4 km·h⁻¹; p = 0.001).

Conclusions

Three weeks of post-exercise sauna bathing effectively induces heat acclimation in females and males, though possibly amid different thermoeffector adaptations. Post-exercise sauna bathing is also an effective ergogenic aid for both sexes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40798-021-00342-6.

Safety and feasibility of symptom-limited cardiopulmonary exercise test using the modified Naughton protocol in children with cerebral palsy: An observational study

ABSTRACT

Variables derived from the cardiopulmonary exercise test (CPX) provide objective information regarding the exercise capacity of children with cerebral palsy (CP), which can be used as the basis for exercise recommendations. Performing maximal CPX might not be appropriate, safe, or practical for children with CP. In the present study, the safety and feasibility of symptom-limited CPX using the modified Naughton protocol, a submaximal protocol, were investigated in children with CP, Gross Motor Function Classification System (GMFCS) level I or II. The present study included 40 children aged 6 to 12 years with CP who underwent symptom-limited CPX. CPX was performed to measure cardiopulmonary fitness using a treadmill with a modified Naughton protocol. Motor capacity was assessed using the Gross Motor Function Measure (GMFM), Pediatric Balance Scale (PBS), Timed Up and Go (TUG) test, and 6-minute walk test. Thirty-seven children with CP successfully completed testing without any adverse events during or immediately after CPX (dropout rate 7.5%). The reason for test termination was dyspnea (51.4%) or leg fatigue (48.6%). Based on the respiratory exchange ratio (RER), 21 of 37 (56.8%) children chose premature termination. The relationship between the reason for test termination and RER was not statistically significant (Spearman rho = 0.082, P = .631). CPX exercise time was strongly correlated with GMFM (Spearman rho = 0.714) and moderate correlation with PBS (Spearman rho = 0.690) and TUG (Spearman rho = 0.537). Peak oxygen uptake during CPX showed a weak correlation with GMFM and a moderate correlation with PBS. This study revealed that symptom-limited CPX using the modified Naughton protocol was safe and feasible for children with CP and GMFCS level I or II.

Determinants of climbing energetic costs in humans

Previous studies in primates and other animals have shown that mass-specific cost of transport (J kg-1 m-1) for climbing is independent of body size across species, but little is known about within-species allometry of climbing costs or the effects of difficulty and velocity. Here, we assessed the effects of velocity, route difficulty and anatomical variation on the energetic cost of climbing within humans. Twelve experienced rock climbers climbed on an indoor wall over a range of difficulty levels and velocities, with energy expenditure measured via respirometry. We found no effect of body mass or limb proportions on mass-specific cost of transport among subjects. Mass-specific cost of transport was negatively correlated with climbing velocity. Increased route difficulty was associated with slower climbing velocities and thus higher costs, but there was no statistically significant effect of route difficulty on energy expenditure independent of velocity. Finally, human climbing costs measured in this study were similar to published values for other primates, suggesting arboreal adaptations have a negligible effect on climbing efficiency.

Prediction Equations for Maximal Aerobic Capacity on Cycle Ergometer for the Spanish Adult Population

BACKGROUND

Frequently used reference values for clinical exercise testing have been derived from non-random samples and some with poorly defined maximal criteria. Our objective was to obtain population based reference values for peak oxygen uptake (V?O₂) and work rate (WR) for cardiopulmonary exercise testing in a representative sample of Caucasian Spanish men and women.

METHODS

182 men and women, 20-85 years old, were included and exercised on cycle-ergometer to exhaustion. (V?O₂) and WR were measured. The equations obtained from this sample were validated in an independent cohort of 69 individuals, randomly sampled form the same population. Then a final equation merging the two cohorts (=251) was produced.

RESULTS

Height, sex and age resulted predictive of both V?O₂ peak and WR. Weight and physical activity added very little to the accuracy to the equations. The formulas V?O₂peak=0.017·height?(cm)-0.023·age?(years)+0.864·sex?(female=0/male=1)±179?l?min^-1, and peak WR=1.345 · height (cm) - 2.074 · age (years)+76.54 · sex (female=0/male=1)±21.2W were the best compromise between accuracy and parsimony.

CONCLUSIONS

This study provides new and accurate V?O₂ peak and WR rate reference values for individuals of European Spanish descent.

Phase Angle Is a Marker of Muscle Quantity and Strength in Overweight/Obese Former Athletes

Background: An increasing body of evidence indicates that the phase angle (PhA) can be applied as a marker of nutritional status, disease prognosis, and mortality probability. Still, it is not known whether PhA can be used as an indicator of muscular quantity and strength and maximal aerobic capacity in overweight/obese former highly active individuals, an understudied population. This study aimed to analyze the association between PhA with skeletal muscle mass, maximal isometric strength, and maximal aerobic capacity through VO2max, in overweight/obese and inactive former athletes. Methods: Cross-sectional information of 94 (62 males) former adult athletes (age: 43.1 ± 9.4 years old; body mass index: 31.4 ± 4.8 kg/m²) taking part in a weight-loss clinical trial was analyzed. Total fat and fat-free mass were determined by dual-energy X-ray absorptiometry, while skeletal muscle mass was predicted from appendicular lean soft tissue. Values for upper- and lower-body maximal isometric strength were assessed by handgrip and leg press dynamometry. VO2max was determined by indirect calorimetry through a graded exercise test performed on a treadmill. Results: PhA was associated with skeletal muscle mass (r = 0.564, p < 0.001), upper-body strength (r = 0.556, p < 0.001), lower-body strength (r = 0.422, p < 0.001), and VO2max (r = 0.328, p = 0.013). These relationships remained significant for skeletal muscle mass (β = 2.158, p = 0.001), maximal isometric strength (upper-body: β = 2.846, p = 0.012; low-er-body: β = 24.209, p = 0.041) after adjusting for age, sex, and fat mass but not for VO2max (β = −0.163, p = 0.098). Conclusion: Our findings indicated that former athletes with higher values of PhA exhibited greater muscle mass and strength, despite sex, age, and body composition, which suggests that this simple raw BI parameter can be utilized as an indicator of muscle quantity and functionality in overweight/obese former athletes.

The effect of multi-ingredient intra- versus extra-cellular buffering supplementation combined with branched-chain amino acids and creatine on exercise-induced ammonia blood concentration and aerobic capacity in taekwondo athletes

Background

This study aimed to investigate the effect of multi-ingredient intra- (BA) versus extra- (ALK) cellular buffering factor supplementation, combined with the customary intake of branched-chain amino acids (BCAA) and creatine malate (TCM), on body composition, exercise variables, and biochemical and hematological parameters in 9 elite taekwondo athletes.

Methods

Eight-week randomized double-blind crossover BA (5.0 g·day⁻¹ of β-alanine) versus ALK (0.07 g·kg_FFM⁻¹·day⁻¹ of sodium bicarbonate) supplementation combined with BCAA (0.2 g·kg_FFM⁻¹·day⁻¹) and TCM (0.05 g·kg_FFM⁻¹·day⁻¹) during a standard 8-week taekwondo training period was implemented. In the course of the experiment, body composition (dual X-ray absorptiometry), aerobic capacity (ergospirometric measurements during an incremental treadmill test until exhaustion), and exercise blood biomarkers concentrations were measured. Data were analyzed using repeated measures within-between interaction analysis of variance with the inclusion of experimental supplementation order.

Results

The maximum post-exercise blood ammonia concentration decreased in both groups after supplementation (from 80.3 ± 10.6 to 72.4 ± 10.2 µmol∙L⁻¹, p = 0.013 in BA; from 81.4 ± 8.7 to 74.2 ± 8.9 µmol∙L⁻¹, p = 0.027 in ALK), indicating reduced exercise-related adenosine triphosphate degradation. However, no differences were found in body composition, aerobic capacity, blood lactate concentration, and hematological parameters after neither BA (combined with BCAA and TCM) nor ALK (combined with BCAA and TCM) supplementation.

Conclusions

In highly trained taekwondo athletes, neither extra- nor intracellular buffering enhancement resulting from BA and ALK supplementation, combined with BCAA and TCM treatment, affects body mass and composition, maximum oxygen uptake, and hematological indices, even though certain advantageous metabolic adaptations can be observed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12970-021-00451-3.

Race Performance Prediction from the Physiological Profile in National Level Youth Cross-Country Cyclists

Cross-country mountain biking is an Olympic sport discipline with high popularity among elite and amateur cyclists. However, there is a scarcity of data regarding the key determinants of performance, particularly in young cross-country cyclists. The aim of this study was to examine the physiological profile of youth national-level cross-country cyclists and to determine those variables that were able to best predict the performance in an official race. Ten youth cross-country cyclists of a national team underwent a complete evaluation that included anthropometric assessments, laboratory tests to evaluate the wattage at blood lactate thresholds and at maximal oxygen uptake (PO_VO2max), and field tests to make an in-depth power profile of the athletes. The data obtained in the above-mentioned tests was analysed along with total and partial race times during a competition belonging to the Union Cycliste Internationale (UCI) calendar. In the present study, large and statistically significant correlations (r = -0.67 to -0.95, p ≤ 0.05) were found between maximal and submaximal indices of aerobic fitness and cycling performance, especially when they were normalised to body mass. A multiple regression analysis demonstrated that the wattage at 2 mmol/L, 4 mmol/L and PO_VO2max were able to explain 82% of the variance in total race time. In summary, the results of this study support the use of maximal and submaximal indices of aerobic power as predictors of performance in youth cross-country cyclists.

The Oxygen Uptake Plateau-A Critical Review of the Frequently Misunderstood Phenomenon

A flattening of the oxygen uptake–work rate relationship at severe exercise indicates the achievement of maximum oxygen uptake \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left({\text{VO}}_{2\max } \right)$$\end{document}VO2max. 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The aim of this investigation was to critically review the influence of research methods and physiological factors on the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2} {\text{pl}}$$\end{document}VO2pl incidence. It is shown that many studies used inappropriate definitions or methodical approaches to check for the occurrence of a \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2} {\text{pl}}$$\end{document}VO2pl. In contrast to the widespread assumptions it is unclear whether there is higher \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2} {\text{pl}}$$\end{document}VO2pl incidence in (uphill) running compared to cycling exercise or in discontinuous compared to continuous incremental exercise tests. Furthermore, most studies that evaluated the validity of supramaximal verification phases, reported verification bout durations, which are too short to ensure that \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2\max }$$\end{document}VO2max have been achieved by all participants. As a result, there is little evidence for a higher \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2} {\text{pl}}$$\end{document}VO2pl incidence and a corresponding advantage for the diagnoses of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2\max }$$\end{document}VO2max when incremental tests are supplemented by supramaximal verification bouts. Preliminary evidence suggests that the occurrence of a \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2} {\text{pl}}$$\end{document}VO2pl in continuous incremental tests is determined by physiological factors like anaerobic capacity, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2}$$\end{document}VO2-kinetics and accumulation of metabolites in the submaximal intensity domain. Subsequent studies should take more attention to the use of valid \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2} {\text{pl}}$$\end{document}VO2pl definitions, which require a cut-off at ~ 50% of the submaximal \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2}$$\end{document}VO2 increase and rather large sampling intervals. Furthermore, if verification bouts are used to verify the achievement of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{{2{\text{peak}}}}$$\end{document}VO2peak/\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2\max }$$\end{document}VO2max, it should be ensured that they can be sustained for sufficient durations.

Validation of a Modified Submaximal Balke Protocol to Assess Cardiorespiratory Fitness in Individuals at High Risk of or With Chronic Health Conditions-A Pilot Study

Objectives: This study aims to validate a submaximal treadmill walking test for estimation of maximal oxygen consumption (VO_2max) in individuals at high risk of or with chronic health conditions. Method: Eighteen participants (age 62 ± 16 years; VO_2max 31.2 ± 5.9 ml kg^-1 min^-1) at high risk of getting or with established chronic diseases performed two valid modified Balke treadmill walking protocols, one submaximal protocol, and one maximal protocol. Test duration, heart rate (HR), and rate of perceived exertion (RPE) were measured during both tests. VO_2max was measured during the maximal test. VO_2max was estimated from the submaximal test by multiple regression using time to RPE ≥ 17, gender, age, and body mass as independent variables. Model fit was reported as explained variance (R ²) and standard error of the estimate (SEE). Results: The model fit for estimation of VO_2max from time to RPE ≥ 17 at the submaximal test, body mass, age, and gender was R ² = 0.78 (SEE = 3.1 ml kg^-1 min^-1, p ≤ 0.001). Including heart rate measurement did not improve the model fit. Conclusions: The submaximal walking test is feasible and valid for assessing cardiorespiratory fitness in individuals with high risk of or chronic health conditions.

Effect of four different forms of high intensity training on BDNF response to Wingate and Graded Exercise Test

This study examined the effects of a nine-week intervention of four different high-intensity training modalities [high-intensity functional training (HIFT), high-intensity interval training (HIIT), high-intensity power training (HIPT), and high-intensity endurance training (HIET)] on the resting concentration of brain-derived neurotropic factor (BDNF). In addition, we evaluated the BDNF responses to Graded Exercise Test (GXT) and Wingate Anaerobic Test (WAnT) in men. Thirty-five healthy individuals with body mass index 25.55 ± 2.35 kg/m2 voluntarily participated in this study and were randomly assigned into four training groups. During nine-weeks they completed three exercise sessions per week for one-hour. BDNF was analyzed before and after a GXT and WAnT in two stages: (stage 0-before training and stage 9-after nine weeks of training). At stage 0, an increase in BDNF concentration was observed in HIFT (33%; p < 0.05), HIPT (36%; p < 0.05) and HIIT (38%; p < 0.05) after GXT. Even though HIET showed an increase in BDNF (10%) this was not statistically significant (p > 0.05). At stage 9, higher BDNF levels after GXT were seen only for the HIFT (30%; p < 0.05) and HIIT (18%; p < 0.05) groups. Reduction in BDNF levels were noted after the WAnT in stage 0 for HIFT (- 47%; p < 0.01), HIPT (- 49%; p < 0.001), HIET (- 18%; p < 0.05)], with no changes in the HIIT group (- 2%). At stage 9, BDNF was also reduced after WAnT, although these changes were lower compared to stage 0. The reduced level of BDNF was noted in the HIFT (- 28%; p < 0.05), and HIPT (- 19%;p < 0.05) groups. Additionally, all groups saw an improvement in VO2max (8%; p < 0.001), while BDNF was also correlated with lactate and minute ventilation and selected WAnT parameters. Our research has shown that resting values of BDNF after nine weeks of different forms of high-intensity training (HIT) have not changed or were reduced. Resting BDNF measured at 3th (before GXT at stage 9) and 6th day after long lasting HITs (before WAnT at stage 9) did not differed (before GXT), but in comparison to the resting value before WAnT at the baseline state, was lower in three groups. It appears that BDNF levels after one bout of exercise is depended on duration time, intensity and type of test/exercise.

Wearing compression tights post-exercise enhances recovery hemodynamics and subsequent cycling performance

PURPOSE

To investigate sports compression garment (CG)-induced recovery hemodynamics and their potential impact on subsequent cycling performance.

METHODS

In a randomized crossover design, 13 physically active men (20.9 ± 1.4 years; 65.9 ± 7.8 kg; 173.3 ± 4.8 cm; peak power output 254.2 ± 27.2 W) underwent 2 experimental trials. During each experimental trial, the subjects performed 20-min fatiguing preload cycling followed by 60-min passive recovery wearing either a sports CG (28.6 ± 9.4 mmHg) or gymnastic pants (CON). A 5-min all-out cycling performance test was subsequently conducted and power output and cadence were recorded. Cardiac output (CO) and stroke volume (SV) were measured using Doppler ultrasound (USCOM®). Heart rate (HR), blood lactate [BLa^-], ratings of perceived exertion (RPE), leg muscle soreness (LMS), mean arterial pressure (MAP) and systemic vascular resistance (SVR) were monitored at 5, 15, 30, 45, 60 min during passive recovery.

RESULTS

During the subsequent 5-min all-out cycling performance test, power output (215.2 ± 24.0 vs. 210.8 ± 21.5 W, CG vs. CON) and cadence (72.5 ± 3.8 vs. 71.2 ± 4.8 rpm, CG vs. CON) were higher in CG than CON (P < 0.05). SV was higher at 15, 30 and 45 min (P < 0.05), CO was higher at 5 and 45 min (P < 0.05), HR was lower at 15 and 30 min (P < 0.05) and [BLa^-] was lower at 5 and 15 min (P < 0.05) during passive recovery, while LMS was lower at all time-points (P < 0.05) compared with CON.

CONCLUSION

Sports CG improves subsequent cycling performance by enhancing hemodynamic responses and attenuating perceived muscle soreness during passive recovery in physically active men.

Walking Initiated 20 Minutes before the Time of Individual Postprandial Glucose Peak Reduces the Glucose Response in Young Men with Overweight or Obesity: A Randomized Crossover Study

BACKGROUND

Although a single bout of postmeal exercise can lower postprandial glucose (PPG), its optimal timing remains unclear.

OBJECTIVE

This study aimed to investigate the effect of exercise timing using an individualized approach on PPG in overweight or obese young men.

METHODS

Twenty men [age: 23.0 ± 4.3 y; BMI (kg/m2): 27.4 ± 2.8] each completed three 240-min trials in a randomized order separated by 6-14 d: 1) sitting (SIT), 2) walking initiated at each participant's PPG-peak time (PPGP) (iP), and 3) walking initiated 20 min before the PPGP (20iP). For each participant, PPGP was predetermined using continuous glucose monitoring. Walking was performed at 50% maximal oxygen consumption for 30 min. Venous blood was collected at 15- and 30-min intervals for 0-120 min and 120-240 min, respectively. The primary outcome was plasma PPG. Generalized estimating equations were used for comparison between trials.

RESULTS

Compared with SIT, the 4-h incremental AUCs (iAUCs) for plasma PPG (-0.6 mmol · L-1 · h; P = 0.047) and insulin (-28.7%, P < 0.001) were reduced in 20iP only, and C-peptide concentrations were lower after iP (-14.9%, P = 0.001) and 20iP (-28.7%, P < 0.001). Plasma insulin (-11.1%, P = 0.006) and C-peptide (-8.3%, P = 0.012) were lower due to the 20iP compared with iP treatment. Finally, PPG reductions due to iP and 20iP occurred only in men with a BMI > 27.5 kg/m2 (iP, -11.2%; 20iP, -14.7%; P = 0.047) and higher glucose iAUC values during SIT (iP, -25.5%; 20iP, -25.7%; P < 0.001).

CONCLUSIONS

Walking initiated 20 min before PPGP lowered PPG and plasma insulin and C-peptide concentrations in young men with overweight or obesity, in particular in those with high BMI or glucose iAUC values during SIT; it also lowered plasma insulin and C-peptide concentrations more effectively than did exercise initiated at PPGP. This trial was registered at the Chinese Clinical Trial Registry (http://www.chictr.org.cn/index.aspx) as ChiCTR1900023175.

Reduced Endurance Capacity and Suboptimal Energy Availability in Top-Level Female Cyclists

PURPOSE

Women's professional cycling has grown in popularity, and this increase is also apparent in Brazil, which has increased its female cycling calendar in recent years. The aim of this observational study was to (1) determine training and competition loads of a top-level Brazilian female cycling team, (2) evaluate nutrition and clinical health, and (3) measure whether exercise capacity changed throughout the season.

METHODS

Training and competition data were collected over the season using global positioning system monitors, while laboratory-based physiological and performance measures (incremental cycling test, 30-s Wingate, 4-km time trial) and clinical and nutritional analyses were performed at time points throughout the season.

RESULTS

Total distance covered over the year was 11,124 (2895) km (7382-14,698 km). Endurance capacity was reduced over the season (P = .005) but not anaerobic power (all P > .05). Nutrition and stress markers remained largely unchanged throughout the season, although there were some individual fluctuations in some measures, and testosterone concentration was low for some. Median estimated energy availability ranged between 32.3 and 56.8 kcal·kgLBM-1·d-1 during training and 26.4 and 53.8 kcal·kgLBM-1·d-1 during competition. Percentage of training spent in optimal estimated energy availability was generally low, with 3 athletes spending <35% within the optimal intake.

CONCLUSIONS

Substantial training and competition loads of the monitored professional Brazilian female cyclists may have reduced exercise capacity toward the end of the season, indicative of a grueling yearlong schedule. Several athletes may have had suboptimal energy availability during the season, potentially affecting testosterone concentration. These data demonstrate the difficulties in maintaining optimal nutrition, health, and performance throughout a season in professional female cycling and highlight the need for quality sport-science support for this type of top-level athlete.

Influence of post-exercise hot-water therapy on adaptations to training over 4 weeks in elite short-track speed skaters

This study aimed to investigate the effects of regular hot water bathing (HWB), undertaken 10 min after the last training session of the day, on chronic adaptations to training in elite athletes. Six short-track (ST) speed skaters completed four weeks of post-training HWB and four weeks of post-training passive recovery (PR) according to a randomized cross-over study. During HWB, participants sat in a jacuzzi (40 °C; 20 min). According to linear mixed models, maximal isometric strength of knee extensor muscles was significantly increased for training with HWB (p < 0.0001; d = 0.41) and a tendency (p = 0.0529) was observed concerning V˙O2max. No significant effect of training with PR or HWB was observed for several variables (p > 0.05), including aerobic peak power output, the decline rate of jump height during 1 min-continuous maximal countermovement jumps (i.e. anaerobic capacity index), and the force-velocity relationship. Regarding specific tasks on ice, a small effect of training was found on both half-lap time and total time during a 1.5-lap all-out exercise (p = 0.0487; d = 0.23 and p = 0.0332; d = 0.21, respectively) but no additional effect of HWB was observed. In summary, the regular HWB protocol used in this study can induce additional effects on maximal isometric strength without compromising aerobic and anaerobic adaptations or field performance in these athletes.

Is a verification phase useful for confirming maximal oxygen uptake in apparently healthy adults? A systematic review and meta-analysis

BACKGROUND

The 'verification phase' has emerged as a supplementary procedure to traditional maximal oxygen uptake (VO2max) criteria to confirm that the highest possible VO2 has been attained during a cardiopulmonary exercise test (CPET).

OBJECTIVE

To compare the highest VO2 responses observed in different verification phase procedures with their preceding CPET for confirmation that VO2max was likely attained.

METHODS

MEDLINE (accessed through PubMed), Web of Science, SPORTDiscus, and Cochrane (accessed through Wiley) were searched for relevant studies that involved apparently healthy adults, VO2max determination by indirect calorimetry, and a CPET on a cycle ergometer or treadmill that incorporated an appended verification phase. RevMan 5.3 software was used to analyze the pooled effect of the CPET and verification phase on the highest mean VO2. Meta-analysis effect size calculations incorporated random-effects assumptions due to the diversity of experimental protocols employed. I2 was calculated to determine the heterogeneity of VO2 responses, and a funnel plot was used to check the risk of bias, within the mean VO2 responses from the primary studies. Subgroup analyses were used to test the moderator effects of sex, cardiorespiratory fitness, exercise modality, CPET protocol, and verification phase protocol.

RESULTS

Eighty studies were included in the systematic review (total sample of 1,680 participants; 473 women; age 19-68 yr.; VO2max 3.3 ± 1.4 L/min or 46.9 ± 12.1 mL·kg-1·min-1). The highest mean VO2 values attained in the CPET and verification phase were similar in the 54 studies that were meta-analyzed (mean difference = 0.03 [95% CI = -0.01 to 0.06] L/min, P = 0.15). Furthermore, the difference between the CPET and verification phase was not affected by any of the potential moderators such as verification phase intensity (P = 0.11), type of recovery utilized (P = 0.36), VO2max verification criterion adoption (P = 0.29), same or alternate day verification procedure (P = 0.21), verification-phase duration (P = 0.35), or even according to sex, cardiorespiratory fitness level, exercise modality, and CPET protocol (P = 0.18 to P = 0.71). The funnel plot indicated that there was no significant publication bias.

CONCLUSIONS

The verification phase seems a robust procedure to confirm that the highest possible VO2 has been attained during a ramp or continuous step-incremented CPET. However, given the high concordance between the highest mean VO2 achieved in the CPET and verification phase, findings from the current study would question its necessity in all testing circumstances.

PROSPERO REGISTRATION ID

CRD42019123540.

Differences between Professional and Amateur Cyclists in Endogenous Antioxidant System Profile

Currently, no studies have examined the differences in endogenous antioxidant enzymes in professional and amateur cyclists and how these can influence sports performance. The aim of this study was to identify differences in endogenous antioxidants enzymes and hemogram between competitive levels of cycling and to see if differences found in these parameters could explain differences in performance. A comparative trial was carried out with 11 professional (PRO) and 15 amateur (AMA) cyclists. All cyclists performed an endogenous antioxidants analysis in the fasted state (visit 1) and an incremental test until exhaustion (visit 2). Higher values in catalase (CAT), oxidized glutathione (GSSG) and GSSG/GSH ratio and lower values in superoxide dismutase (SOD) were found in PRO compared to AMA (p < 0.05). Furthermore, an inverse correlation was found between power produced at ventilation thresholds 1 and 2 and GSSG/GSH (r = −0.657 and r = −0.635; p < 0.05, respectively) in PRO. Therefore, there is no well-defined endogenous antioxidant enzyme profile between the two competitive levels of cyclists. However, there was a relationship between GSSG/GSH ratio levels and moderate and submaximal exercise performance in the PRO cohort.

Isolated and combined effects of high-intensity interval training and time-restricted eating on glycaemic control in reproductive-aged women with overweight or obesity: study protocol for a four-armed randomised controlled trial

INTRODUCTION

Overweight and obesity in reproductive-aged women is a global problem due to the increased risk of subfertility, pregnancy complications and cardiometabolic diseases. High-intensity interval training and time-restricted eating are two primary lifestyle interventions that, independently, have positive effects on a range of health outcomes. Whether these two strategies have synergistic effects is currently unknown. Our primary aim is to determine the isolated and combined effect of high-intensity interval training and time-restricted eating on glycaemic control in reproductive-aged women with overweight/obesity.

METHODS AND ANALYSIS

The study is a randomised controlled trial with four parallel groups. Women (N=120) aged 18-45 years with body mass index ≥27 kg/m² will be randomly allocated (1:1:1:1) to either: (1) high-intensity interval training, (2) time-restricted eating, (3) a combination of high-intensity interval training and of time-restricted eating, or (4) a control group. The duration of each intervention will be 7 weeks. The primary outcome measure will be glycaemic control, determined by the total area under the plasma glucose curve over 2 hours after a 75-gram oral glucose tolerance test. Secondary outcome measurements will include markers of cardiovascular and metabolic health (peak oxygen uptake, blood pressure, blood lipids, body composition, insulin sensitivity), sleep quality, physical activity, diet and adherence rates to the intervention.

ETHICS AND DISSEMINATION

The Regional Committee Medical Research Ethics, Norway has approved the trial protocol. This study will provide important new knowledge to both the scientific community and the general population about the isolated and combined effects of two novel diet-exercise strategies on cardiovascular and metabolic health among women with overweight/obesity.

TRIAL REGISTRATION NUMBER

NCT04019860.

Validation and Practical Applications of Performance in a 6-Min Rowing Test in the Danish Armed Forces

Personnel of the Danish Armed Forces must complete a yearly basic physical fitness test consisting of a Cooper’s 12-min run test (CRT) and four strength-related bodyweight exercises. However, there is no validated alternative to the CRT allowing injured or sailing personnel to conduct the yearly basic physical fitness test. Therefore, the aim of this study was to validate performance in a 6-min rowing ergometer test (6MRT) against CRT performance. Thirty-one individuals (M/F: 20/11, age: 34 ± 12 years) employed at the Danish Armed Forces completed testing on two independent days; (I) the CRT on an outdoor track and (II) a 6MRT with pulmonary measurements of breath-by-breath oxygen uptake. In addition, 5 participants (M/F: 4/1, age: 40 ± 10 years) completed re-testing of the 6MRT. No difference was observed between VO_2max estimated from the CRT and measured during the 6MRT. Absolute VO_2max correlated strongly (r = 0.95; p < 0.001) to performance in the 6MRT, and moderately (r = 0.80; p < 0.001) to performance in the CRT. Bodyweight (BW) and fat free mass (FFM) correlated stronger to performance in the 6MRT compared to the CRT. 6MRT re-testing yielded similar performance results. The 6MRT is a valid and reliable alternative to the CRT, allowing injured or sailing personnel of the Danish Armed Forces to complete the basic physical fitness test as required, albeit 6MRT performance demands must be made relative to bodyweight.

Efficacy of Popular Diets Applied by Endurance Athletes on Sports Performance: Beneficial or Detrimental? A Narrative Review

Endurance athletes need a regular and well-detailed nutrition program in order to fill their energy stores before training/racing, to provide nutritional support that will allow them to endure the harsh conditions during training/race, and to provide effective recovery after training/racing. Since exercise-related gastrointestinal symptoms can significantly affect performance, they also need to develop strategies to address these issues. All these factors force endurance athletes to constantly seek a better nutritional strategy. Therefore, several new dietary approaches have gained interest among endurance athletes in recent decades. This review provides a current perspective to five popular diet approaches: (a) vegetarian diets, (b) high-fat diets, (c) intermittent fasting diets, (d) gluten-free diet, and (e) low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diets. We reviewed scientific studies published from 1983 to January 2021 investigating the impact of these popular diets on the endurance performance and health aspects of endurance athletes. We also discuss all the beneficial and harmful aspects of these diets, and offer key suggestions for endurance athletes to consider when following these diets.

Changes in pulmonary function and feasibility of portable continuous laryngoscopy during maximal uphill running

Objective

To evaluate changes in pulmonary function and feasibility of portable continuous laryngoscopy during maximal uphill running.

Methods

Healthy volunteers participated in an uphill race. Forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC) were obtained before and 5 and 10 min after finishing the race. Capillary blood lactate concentration ([BLa^-]) and Borg score for perceived exertion were registered immediately after the race. One participant wore a portable video-laryngoscope during the race, and the video was assessed for technical performance.

Results

Twenty adult subjects participated with a mean (SD) age of 40.2 (9.7) years. Mean (SD) race duration and post-exercise [BLa^-] was 13.9 (2.3) min and 10.7 (2.1) mmol/L, respectively, and the median (range) Borg score for perceived exertion was 9 (5–10).

Mean percentage change (95% CI) 5 and 10 min post-exercise in FEV₁ were 6.9 (3.7 to 10.2) % and 5.9 (2.7 to 9.0) %, respectively, and in FVC 5.2 (2.3 to 8.1) % and 4.7 (1.6 to 7.9) %, respectively. The recorded video of the larynx was of good quality.

Conclusions

Maximal aerobic field exercise induced bronchodilatation in the majority of the healthy non-asthmatic participants. It is feasible to perform continuous video-laryngoscopy during heavy uphill exercise.

Aerobic Capacity According to Playing Role and Position in Elite Female Basketball Players Using Laboratory and Field Tests

PURPOSE

To compare the aerobic capacity of elite female basketball players between playing roles and positions determined using maximal laboratory and field tests.

METHODS

Elite female basketball players from the National Croatian League were grouped according to playing role (starter: n = 8; bench: n = 12) and position (backcourt: n = 11; frontcourt: n = 9). All 20 players completed 2 maximal exercise tests in a crossover fashion 7 days apart. First, the players underwent a laboratory-based continuous running treadmill test with metabolic measurement to determine their peak oxygen uptake (VO2peak). The players then completed a maximal field-based 30-15 Intermittent Fitness Test (30-15 IFT) to estimate VO2peak. The VO2peak was compared using multiple linear regression analysis with bootstrap standard errors and playing role and position as predictors.

RESULTS

During both tests, starters attained a significantly higher VO2peak than bench players (continuous running treadmill: 47.4 [5.2] vs 44.7 [3.5] mL·kg-1·min-1, P = .05, moderate; 30-15 IFT: 44.9 [2.1] vs 41.9 [1.7] mL·kg-1·min-1, P < .001, large), and backcourt players attained a significantly higher VO2peak than frontcourt players (continuous running treadmill: 48.1 [3.8] vs 43.0 [3.3] mL·kg-1·min-1, P < .001, large; 30-15 IFT: 44.2 [2.2] vs 41.8 [2.0] mL·kg-1·min-1, P < .001, moderate).

CONCLUSIONS

Starters (vs bench players) and guards (vs forwards and centers) possess a higher VO2peak irrespective of using laboratory or field tests. These data highlight the role- and position-specific importance of aerobic fitness to inform testing, training, and recovery practices in elite female basketball.

Intermittent post-exercise sauna bathing improves markers of exercise capacity in hot and temperate conditions in trained middle-distance runners

PURPOSE

This study investigated whether intermittent post-exercise sauna bathing across three-weeks endurance training improves exercise heat tolerance and exercise performance markers in temperate conditions, compared to endurance training alone. The subsidiary aim was to determine whether exercise-heat tolerance would further improve following 7-Weeks post-exercise sauna bathing.

METHODS

Twenty middle-distance runners (13 female; mean ± SD, age 20 ± 2 years, [Formula: see text]O_2max 56.1 ± 8.7 ml kg^-1 min^-1) performed a running heat tolerance test (30-min, 9 km h^-1/2% gradient, 40 °C/40%RH; HTT) and temperate (18 °C) exercise tests (maximal aerobic capacity [[Formula: see text]O_2max], speed at 4 mmol L^-1 blood lactate concentration ([La^-]) before (Pre) and following three-weeks (3-Weeks) normal training (CON; n = 8) or normal training with 28 ± 2 min post-exercise sauna bathing (101-108 °C, 5-10%RH) 3 ± 1 times per week (SAUNA; n = 12). Changes from Pre to 3-Weeks were compared between-groups using an analysis of co-variance. Six SAUNA participants continued the intervention for 7 weeks, completing an additional HTT (7-Weeks; data compared using a one-way repeated-measures analysis of variance).

RESULTS

During the HTT, SAUNA reduced peak rectal temperature (T_rec; - 0.2 °C), skin temperature (- 0.8 °C), and heart rate (- 11 beats min^-1) more than CON at 3-Weeks compared to Pre (all p < 0.05). SAUNA also improved [Formula: see text]O_2max (+ 0.27 L^-1 min^-1; p = 0.02) and speed at 4 mmol L^-1 [La^-] (+ 0.6 km h^-1; p = 0.01) more than CON at 3-Weeks compared to Pre. Only peak T_rec (- 0.1 °C; p = 0.03 decreased further from 3-Weeks to 7-Weeks in SAUNA (other physiological variables p > 0.05).

CONCLUSIONS

Three-weeks post-exercise sauna bathing is an effective and pragmatic method of heat acclimation, and an effective ergogenic aid. Extending the intervention to seven weeks only marginally improved T_rec.

Does heart rate response confirm the attainment of maximal oxygen uptake in adults 45 years and older?

PURPOSE

To test the efficacy of a plateau in heart rate (HR_plat) as an effective indicator for confirming [Formula: see text]max attainment in a middle-aged to older sample.

METHODS

Nine men and eleven women (age 60 ± 8.5 years, [Formula: see text]max 35.9 ± 9.4 ml/kg/min, N = 20) completed a single [Formula: see text]max test on both the treadmill and cycle ergometer.[Formula: see text]max was confirmed using a plateau in [Formula: see text] ([Formula: see text]_plat) of ≤ 150 ml/min, a verification bout, and HR_plat (≤ 4 bpm).

RESULTS

[Formula: see text]_plat occurred in 100% and 95% of participants on the treadmill and cycle ergometer, respectively. Verification criteria ([Formula: see text]max during verification ≤ 2% of [Formula: see text]max during incremental test) were met by 80% of participants on both modalities. HR_plat was achieved by 90% and 70% of participants on the treadmill and cycle ergometer, respectively.

CONCLUSION

These results suggest that a verification bout is reliable for confirming [Formula: see text]max in older adults on both modalities. In our sample of middle-aged and older adults, [Formula: see text]_plat was the most robust method to assess [Formula: see text]max when indirect calorimetry is available. Although more research is warranted, when indirect calorimetry is not available, a HR_plat of ≤ 4 bpm may be a useful alternative to get an accurate representation of maximal effort in middle-aged and older adults.

Construct validation of the leisure time physical activity questionnaire for people with SCI (LTPAQ-SCI)

STUDY DESIGN

Cross-sectional construct validation study.

OBJECTIVES

To test the construct validity of the Leisure Time Physical Activity Questionnaire for People with Spinal Cord Injury (LTPAQ-SCI) by examining associations between the scale responses and cardiorespiratory fitness (CRF) in a sample of adults living with spinal cord injury (SCI).

SETTING

Three university-based laboratories in Canada.

METHODS

Participants were 39 adults (74% male; M age: 42 ± 11 years) with SCI who completed the LTPAQ-SCI and a graded exercise test to volitional exhaustion using an arm-crank ergometer. One-tailed Pearson's correlation coefficients were computed to examine the association between the LTPAQ-SCI measures of mild-, moderate-, heavy-intensity and total minutes per week of LTPA and CRF (peak volume of oxygen consumption [V̇O_2peak] and peak power output [PO_peak]).

RESULTS

Minutes per week of mild-, moderate- and heavy-intensity LTPA and total LTPA were all positively correlated with V̇O_2peak. The correlation between minutes per week of mild intensity LTPA and V̇O_2peak was small-medium (r = 0.231, p = 0.079) while all other correlations were medium-large (rs ranged from 0.276 to 0.443, ps < 0.05). Correlations between the LTPAQ-SCI variables and PO_peak were also positive but small (rs ranged from 0.087 to 0.193, ps > 0.05), except for a medium-sized correlation between heavy-intensity LTPA and PO_peak (r = 0.294, p = 0.035).

CONCLUSIONS

People with SCI who report higher levels of LTPA on the LTPAQ-SCI also demonstrate greater levels of CRF, with stronger associations between moderate- and heavy-intensity LTPA and CRF than between mild-intensity LTPA and CRF. These results provide further support for the construct validity of the LTPAQ-SCI as a measure of LTPA among people with SCI.

Prediction Equations for Maximal Aerobic Capacity on Cycle Ergometer for the Spanish Adult Population

BACKGROUND

Frequently used reference values for clinical exercise testing have been derived from non-random samples and some with poorly defined maximal criteria. Our objective was to obtain population based reference values for peak oxygen uptake (V˙O2) and work rate (WR) for cardiopulmonary exercise testing in a representative sample of Caucasian Spanish men and women.

METHODS

182 men and women, 20-85 years old, were included and exercised on cycle-ergometer to exhaustion. (V˙O2) and WR were measured. The equations obtained from this sample were validated in an independent cohort of 69 individuals, randomly sampled form the same population. Then a final equation merging the two cohorts (=251) was produced.

RESULTS

Height, sex and age resulted predictive of both V˙O2 peak and WR. Weight and physical activity added very little to the accuracy to the equations. The formulas V˙O2peak=0.017⋅height(cm)-0.023⋅age(years)+0.864⋅sex(female=0/male=1)±179lmin-1, and peak WR=1.345 · height (cm) - 2.074 · age (years)+76.54 · sex (female=0/male=1)±21.2W were the best compromise between accuracy and parsimony.

CONCLUSIONS

This study provides new and accurate V˙O2 peak and WR rate reference values for individuals of European Spanish descent.

Acute Photobiomodulation Does Not Influence Specific High-Intensity and Intermittent Performance in Female Futsal Players

The acute improvement of performance after photobiomodulation therapy (PBMT) has been reported in different types of exercise. However, the effect on high-intensity and intermittent exercises that are relevant for team sports is unknown. Thus, we evaluated the effect of prior acute application of PBMT on high-intensity and intermittent exercise performance, muscle oxygenation, and physiological/perceptual indicators in amateur female futsal players. Thirteen players (24.1 ± 3.7 years) performed a testing battery (countermovement jump (CMJ), Illinois agility and YoYo intermittent recovery test level 1 (YYIR1)) preceded by 15 min of PBMT (1 min 30 s each muscular point; five muscular points in each lower limbs) or 15 min of placebo (SHAM), in a counterbalanced randomized cross-over design (one-week in-between PBMT/SHAM). All test performance did not differ (p > 0.05) between PBMT and SHAM, as well as blood lactate, rating of perceived exertion, heart rate, and muscle oxygenation (via near infrared spectroscopy) responses. The acute application of PBMT prior to a physical testing battery does not influence high-intensity and intermittent exercises performance, neither physiological nor perceptual responses in amateur female futsal players.

p-Synephrine, the main protoalkaloid of Citrus aurantium, raises fat oxidation during exercise in elite cyclists

The aim of this study was to investigate the acute effects of p-synephrine ingestion on substrate oxidation during exercise in elite cyclists. Fifteen elite cyclists volunteered to participate in a double blind, crossover, randomized and placebo-controlled experimental trial. During two different trials, participants either ingested a placebo (cellulose) or 3 mg/kg of p-synephrine. After 60 min for substances absorption, participants performed an incremental maximal cycle ergometer test until volitional fatigue (25 W/min). Breath-by-breath gas exchange data was continuously recorded during the entire test to estimate energy expenditure, carbohydrate oxidation, and fat oxidation rates by stoichiometric equations. Heart rate was continuously measured by using a heart rate monitor. The ingestion of p-synephrine had no significant effects on energy expenditure (F = 0.71, P = 0.40) or heart rate (F = 0.66, P = 0.43) during exercise. However, there was a main effect of p-synephrine to increase the rate of fat oxidation over the placebo (F = 5.1, P = 0.04) and the rate of fat oxidation was higher with p-synephrine in the following loads: 45 ± 2%, 51 ± 3%, 62 ± 3%, 67 ± 4%, 79 ± 5% and 85 ± 5% of the maximum wattage obtained in the test (all P < 0.05). The ingestion of p-synephrine did not modify the maximal rate of fat oxidation during the ramp test (mean value; 95%CI =  0.91; 0.79-1.03 vs 1.01; 0.91-1.11 g/min, respectively, P = 0.06) nor the exercise intensity at which maximal fat oxidation was achieved (i.e. Fatmax =  49; 48-53 vs 50; 47-51% Wmax, P = 0.52). Acute p-synephrine ingestion moved the fat oxidation-exercise intensity curve upwards during an incremental cycling test without affecting Fatmax.

The test-retest reliability of individualized VO2peak test modalities in people with spinal cord injury undergoing rehabilitation

STUDY DESIGN

Test-retest study.

OBJECTIVE

To describe the test-retest reliability of an individualized approach for peak oxygen uptake (VO₂peak) testing in a clinical context, accommodating inpatients with heterogeneous levels of physical functioning.

SETTING

Inpatient rehabilitation.

METHOD

Test-retest on two types of devices (recumbent stepper and arm-crank ergometer) with two predefined protocols of varying load increments on each device. No participants performed all four test modalities. VO₂peak, respiratory exchange ratio (RER), peak workload, and the reason for termination were reported. Of 23 participants included, 21 completed the test-retest procedure. Participants were inpatients, ≥18 years, who sustained a spinal cord injury (SCI) within the last 12 months at the time of admission. The median age was 52 years and 74% were male. Median time since injury at the time of the first test (T1) was 5.5 months. Seventeen were classified as American Spinal Injury Association Impairment Scale D. Intraclass correlation coefficients (ICC) and Bland-Altman plots for VO₂peak was calculated to determine intra- and intertester reliability of VO₂peak.

RESULTS

Mean VO₂peak obtained at T1 was 1.91 L/min (95%CI: 1.31-2.51); 1.26 L/min and 2.69 L/min for the recumbent stepper protocols; 0.61 L/min and 1.39 L/min for the arm-crank ergometer protocols. ICC for intra- and intertester reliability was 0.997 (95%CI: 0.986-0.999) and 0.994 (95%CI: 0.978-0.998) respectively. Bland-Altman plots showed a mean difference of -0.005 (SD 0,12) for overall test-retest.

CONCLUSION

Test-retest reliability was high. Mean VO₂peak at discharge from rehabilitation was higher than previously reported and individualized test modalities seemed to yield more optimal results in a heterogenous and representative sample during rehabilitation.

Progress Update and Challenges on V . O2max Testing and Interpretation

The maximal oxygen uptake ( V . O2max) is the primary determinant of endurance performance in heterogeneous populations and has predictive value for clinical outcomes and all-cause mortality. Accurate and precise measurement of V . O2max requires the adherence to quality control procedures, including combustion testing and the use of standardized incremental exercise protocols with a verification phase preceded by an adequate familiarization. The data averaging strategy employed to calculate the V . O2max from the breath-by-breath data can change the V . O2max value by 4-10%. The lower the number of breaths or smaller the number of seconds included in the averaging block, the higher the calculated V . O2max value with this effect being more prominent in untrained subjects. Smaller averaging strategies in number of breaths or seconds (less than 30 breaths or seconds) facilitate the identification of the plateau phenomenon without reducing the reliability of the measurements. When employing metabolic carts, averaging intervals including 15-20 breaths or seconds are preferable as a compromise between capturing the true V . O2max and identifying the plateau. In training studies, clinical interventions and meta-analysis, reporting of V . O2max in absolute values and inclusion of protocols and the averaging strategies arise as imperative to permit adequate comparisons. Newly developed correction equations can be used to normalize V . O2max to similar averaging strategies. A lack of improvement of V . O2max with training does not mean that the training program has elicited no adaptations, since peak cardiac output and mitochondrial oxidative capacity may be increased without changes in V . O2max.

Maximal Oxygen Uptake Adjusted for Skeletal Muscle Mass in Competitive Speed-Power and Endurance Male Athletes: Changes in a One-Year Training Cycle

We compared the changes in maximum oxygen uptake (V·O2max) calculated per skeletal muscle mass (SMM) with conventional V·O2max measures in a 1-year training cycle. We hypothesized that the pattern of changes would differ between SMM-adjusted and absolute or weight-adjusted values, and the differences between groups of distinct training specialization and status will depend on the measure used. Twelve sprinters (24.7 ± 3.3 years), 10 endurance runners (25.3 ± 5.3 years), and 10 recreationally trained controls (29 ± 4.5 years) performed a treadmill test until exhaustion to determine V·O2max. Their SMM was estimated based on the dual X-ray absorptiometry method and a regression equation. The significance of differences was assessed using analysis of variance (p ≤ 0.05). The pattern of the longitudinal change was not different between V·O2max/SMM and standard measures. Also, the significance of differences between sprinters and endurance athletes remained similar regardless of the V·O2max measure. Sprinters and controls had similar absolute (~4.3 L·min⁻¹) and total weight-adjusted (~52 vs. ~56 mL·min⁻¹·kg) V·O2max, but they significantly differed in SMM-adjusted V·O2max (~110 vs. ~130 mL·min⁻¹·kg SMM⁻¹). In summary, SMM-adjusted V·O2max is not more useful than standard measures to track longitudinal changes in competitive athletes. However, it allows to better distinguish between groups or individuals differing in training status. The results of our study are limited to male athletes.

Effect of ambient temperature on fat oxidation during an incremental cycling exercise test

Aim: The objective of this current research was to compare fat oxidation rates during an incremental cycling exercise test in a temperate vs. hot environment.Methods: Twelve healthy young participants were recruited for a randomised crossover experimental design. Each participant performed a VO_2max test in a thermoneutral environment followed by two cycling ramp test trials, one in a temperate environment (18.3°C) and another in a hot environment (36.3°C). The ramp test consisted of 3-min stages of increasing intensity (+10% of VO_2max) while gas exchange, heart rate and perceived exertion were measured.Results: During exercise, there was a main effect of the environment temperature on fat oxidation rate (F = 9.35, P = 0.014). The rate of fat oxidation was lower in the heat at 30% VO_2max (0.42 ± 0.15 vs.0.37 ± 0.13 g/min; P = 0.042), 60% VO_2max (0.37 ± 0.27 vs.0.23 ± 0.23 g/min; P = 0.018) and 70% VO_2max (0.22 ± 0.26 vs.0.12 ± 0.26 g/min; P = 0.007). In addition, there was a tendency for a lower maximal fat oxidation rate in the heat (0.55 ± 0.2 vs.0.48 ± 0.2 g/min; P = 0.052) and it occurred at a lower exercise intensity (44 ± 14 vs.38% ± 8% VO_2max; P = 0.004). The total amount of fat oxidised was lower in the heat (5.8 ± 2.6 vs 4.6 ± 2.8 g; P = 0.002). The ambient temperature also produced main effects on heart rate (F = 15.18, P = 0.005) and tympanic temperature (F = 25.23, P = 0.001) with no effect on energy expenditure (F = 0.01, P = 0.945).Conclusion: A hot environment notably reduced fat oxidation rates during a ramp exercise test. Exercising in the heat should not be recommended for those individuals seeking to increase fat oxidation during exercise.

The Relationship between CrossFit® Performance and Laboratory-Based Measurements of Fitness

To date, research has examined the physiological determinants of performance in standardized CrossFit^® (CF) workouts but not without the influence of CF familiarity. Therefore, the purpose of this present study was to examine the predictive value of aerobic fitness, body composition, and total body strength on performance of two standardized CF workouts in CF-naïve participants. Twenty-two recreationally trained individuals (males = 13, females = 9) underwent assessments of peak oxygen consumption (VO₂ peak), ventilatory thresholds, body composition, and one repetition maximum tests for the back squat, deadlift, and overhead press in which the sum equaled the CF Total. Participants also performed two CF workouts: a scaled version of the CF Open workout 19.1 and a modified version of the CF Benchmark workout Fran to determine scores based on total repetitions completed and time-to-completion, respectively. Simple Pearson’s r correlations were used to determine the relationships between CF performance variables (19.1 and modified Fran) and the independent variables. A forward stepwise multiple linear regression analysis was performed and significant variables that survived the regression analysis were used to create a predictive model of CF performance. Absolute VO₂ peak was a significant predictor of 19.1 performance, explaining 39% of its variance (adjusted R² = 0.39, p = 0.002). For modified Fran, CF Total was a significant predictor and explained 33% of the variance in performance (adjusted R² = 0.33, p = 0.005). These results suggest, without any influence of CF familiarity or experience, that performance in these two CF workouts could be predicted by distinct laboratory-based measurements of fitness.

The Effect of a 7-Week Training Period on Changes in Skin NADH Fluorescence in Highly Trained Athletes

The study aimed to evaluate the changes of nicotinamide adenine dinucleotide (NADH) fluorescence in the reduced form in the superficial skin layer, resulting from a 7-week training period in highly trained competitive athletes (n = 41). The newly, non-invasive flow mediated skin fluorescence (FMSF) method was implemented to indirectly evaluate the mitochondrial activity by NADH fluorescence. The FMSF measurements were taken before and after an exercise treadmill test until exhaustion. We found that athletes showed higher post-training values in basal NADH fluorescence (pre-exercise: 41% increase; post-exercise: 49% increase). Maximum NADH fluorescence was also higher after training both pre- (42% increase) and post-exercise (47% increase). Similar changes have been revealed before and after exercise for minimal NADH fluorescence (before exercise: 39% increase; after exercise: 47% increase). In conclusion, physical training results in an increase in the skin NADH fluorescence levels at rest and after exercise in athletes.

Maximum oxygen consumption and quantification of exercise intensity in untrained male Wistar rats

This study aimed to explore a valid test protocol for measuring VO_2max in healthy untrained male Wistar rats of different ages and quantifying the exercise intensity (%VO_2max) of running under different treadmill grades and speeds. The test protocols and %VO_2max will provide a reference for the design of exercise intensity. We tested male Wistar rats aged 4 weeks, 10 weeks, 10 months and 16 months old with three test protocols (Procedure 1 [P1], 2 [P2] and 3 [P3]) for each age group to quantify VO_2max. We analysed VO_2max, respiratory exchange ratio and test duration to determine an optimal test protocol of VO_2max for different age groups. We used the optimal test protocol to explore the changes in age-related VO_2max. Finally, %VO_2max of running under different treadmill speeds and grades was quantified. VO_2max of Wistar rats decreased significantly after the age of 4 weeks (p < 0.05). The optimum VO_2max can be induced by personalised protocols for different ages. In 4-week-old Wistar rats, the highest VO_2max values were attained by P1 (104.4 ± 6.9 mL · kg⁻¹ · min⁻¹, p = 0.032). The highest VO_2max value (84.7 ± 3.7 mL · kg⁻¹ · min⁻¹, p = 0.037) of 8-week-old Wistar rats was attained in P2. In 10-month-old Wistar rats, the highest VO_2max value was obtained in P3 (63.3 ± 1.7 mL · kg⁻¹ · min⁻¹). This work could be used as a reference for assessing aerobic capacity in studies on exercise intervention with untrained male Wistar rats. However, the %VO_2max measurements at various treadmill speeds and grades only apply to untrained male Wistar rats.

Changes in cardiorespiratory fitness and activity levels over the first year after discharge in ambulatory persons with recent incomplete spinal cord injury

Study design

Secondary analysis of a clinical trial.

Objectives

To investigate changes in cardiorespiratory fitness (CRF) and activity level in ambulatory persons with SCI during the first year after discharge from inpatient rehabilitation.

Setting

Sunnaas Rehabilitation Hospital, Nesoddtangen, Norway.

Methods

Thirty persons with incomplete SCI, all community walkers (25 males and 5 females, 18–69 years old) were recruited to a clinical trial of a 12 weeks home-based aerobic exercise program of either high or moderate intensity. During the last week of inpatient rehabilitation (baseline), participants performed a maximal exercise test on a treadmill (peak oxygen uptake; peak VO₂) and a 6-min walking test (6MWT). Also, total daily energy expenditure (TDEE) and daily amount of steps were measured continuously during 7 days in the participants’ homes. All tests were repeated after 3 and 12 months (post tests).

Results

Twenty of the 30 clinical trial participants performed baseline and both posttests and are included in this secondary analysis. We found no statistically significant between-group differences in the time course over the first year of either peak VO₂, 6MWT, or physical activity outcomes. Therefore, data from both exercise groups and the control group were merged for secondary analyses, revealing statistically significant increase over time in peak VO₂, 6MWT, and TDEE. The increase over time in the average daily steps did not reach statistical significance.

Conclusions

Ambulatory persons with SCI were able to increase their CRF levels over the first year after discharge from inpatient rehabilitation, despite a minimal increase in activity levels.

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.