VO2max Research Articles

Cardiopulmonary and metabolic responses during a 2-day CPET in myalgic encephalomyelitis/chronic fatigue syndrome: translating reduced oxygen consumption to impairment status to treatment considerations

BackgroundPost-exertional malaise (PEM), the hallmark symptom of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), represents a constellation of abnormal responses to physical, cognitive, and/or emotional exertion including profound fatigue, cognitive dysfunction, and exertion intolerance, among numerous other maladies. Two sequential cardiopulmonary exercise tests (2-d CPET) provide objective evidence of abnormal responses to exertion in ME/CFS but validated only in studies with small sample sizes. Further, translation of results to impairment status and approaches to symptom reduction are lacking.MethodsParticipants with ME/CFS (Canadian Criteria; n = 84) and sedentary controls (CTL; n = 71) completed two CPETs on a cycle ergometer separated by 24 h. Two-way repeated measures ANOVA compared CPET measures at rest, ventilatory/anaerobic threshold (VAT), and peak effort between phenotypes and CPETs. Intraclass correlations described stability of CPET measures across tests, and relevant objective CPET data indicated impairment status. A subset of case–control pairs (n = 55) matched for aerobic capacity, age, and sex, were also analyzed.ResultsUnlike CTL, ME/CFS failed to reproduce CPET-1 measures during CPET-2 with significant declines at peak exertion in work, exercise time, V˙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{\ ext{V}}$$\\end{document}e, V˙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{\ ext{V}}$$\\end{document}O2, V˙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{\ ext{V}}$$\\end{document}CO2, V˙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{\ ext{V}}$$\\end{document}T, HR, O2pulse, DBP, and RPP. Likewise, CPET-2 declines were observed at VAT for V˙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{\ ext{V}}$$\\end{document}e/V˙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{\ ext{V}}$$\\end{document}CO2, PetCO2, O2pulse, work, V˙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{\ ext{V}}$$\\end{document}O2 and SBP. Perception of effort (RPE) exceeded maximum effort criteria for ME/CFS and CTL on both CPETs. Results were similar in matched pairs. Intraclass correlations revealed greater stability in CPET variables across test days in CTL compared to ME/CFS owing to CPET-2 declines in ME/CFS. Lastly, CPET-2 data signaled more severe impairment status for ME/CFS compared to CPET-1.ConclusionsPresently, this is the largest 2-d CPET study of ME/CFS to substantiate impaired recovery in ME/CFS following an exertional stressor. Abnormal post-exertional CPET responses persisted compared to CTL matched for aerobic capacity, indicating that fitness level does not predispose to exertion intolerance in ME/CFS. Moreover, contributions to exertion intolerance in ME/CFS by disrupted cardiac, pulmonary, and metabolic factors implicates autonomic nervous system dysregulation of blood flow and oxygen delivery for energy metabolism. The observable declines in post-exertional energy metabolism translate notably to a worsening of impairment status. Treatment considerations to address tangible reductions in physiological function are proffered.Trial registration number: ClinicalTrials.gov, retrospectively registered, ID# NCT04026425, date of registration: 2019-07-17.

EFFECTS OF VARIATION IN EXERCISE TRAINING LOAD ON COGNITIVE PERFORMANCES AND NEUROTROPHIC BIOMARKERS IN PATIENTS WITH CORONARY ARTERY DISEASE.

This study compared the effects of linear (LP) and non-linear (NLP) training periodization on resting cognitive functions, neurotrophic biomarkers (brain-derived neurotrophic factor [BDNF], insulin-like growth factor-1 [IGF-1]), and cathepsin-B in patients with coronary artery disease (CAD). Forty-four patients with CAD reported to our laboratory on two occasions to undergo testing procedures before and after training sessions, and were then blindly randomized to NLP or LP for 36 training sessions. Visit 1 included blood samples and a maximal cardiopulmonary exercise testing to get maximal oxygen uptake (V̇O2peak). Visit 2 included cognitive functions assessment. Thirty-nine patients completed the study (LP: n=20, NLP: n=19), with no observed changes in cognitive performances after the training intervention in either group. IGF-1 concentration decreased in both groups (time-effect: p<0.001), while BDNF concentration increased (time-effect: p<0.05) without interaction (p=0.17 and p=0.65, respectively), and cathepsin-B did not change after the intervention (p>0.05). Associations were found between ΔV̇O2peak and ΔBDNF (R2=0.18, p=0.04), and ΔIGF-1 and Δ short-term/working memory (R2=0.17, p=0.01) in the pooled sample, with Δ IGF-1 and ΔBDNF accounting for 10% of the variance in Δ short-term/working memory. In the LP group, associations were found between ΔV̇O2peak and ΔBDNF (R2=0.45, p=0.02), ΔBDNF and Δ short-term/working memory (R2=0.62, p=0.004), ΔIGF-1 and Δ short-term/working memory (R2=0.31, p=0.01), and Δ IGF-1 and Δ executive function (R2=0.22, p=0.04). This finding highlights the potential importance of monitoring and targeting BDNF and IGF-1 concentration as potential biomarkers for improving short-term and working memory in the population with CAD.

Assessing the Validity of Two Non-Exercise Regression Equations for Predicting Maximal Oxygen Consumption

ABSTRACT Purpose: This study aimed to develop two regression equations to predict maximal oxygen consumption (VO2max) using non-exercise data from a substantial cohort of healthy Iranian adult males. Additionally, this study sought to examine the predictive accuracy of these equations across four different levels of physical activity. Methods: A total of 126 participants (age: 34.9 ± 11.3 years, body mass index [BMI]: 24.9 ± 2.7 kg/m², and body fat percentage [BF%]: 18.3 ± 4.9) completed a maximal graded exercise test to measure VO2max, with a mean of 45.0 ± 3.4 ml.kg−1.min−1. Participants also provided information on age, current physical activity rating (PA-R), and either BMI or BF% to estimate VO2max using Jackson and colleagues’ regression equations. The PA-R was assessed via a standardized questionnaire and categorized into four levels: sedentary, low, moderate, and high. Results: The key findings from this study indicate that both original models significantly underestimated actual VO2max in a large cohort of Iranian adults (both, p < .001 and mean differences exceeding 2.19 ml.kg−1.min−1). Nevertheless, these models provided accurate predictions for VO2max among individuals with moderate levels of physical activity (both, p > .08 and mean differences between 0.51 and 1.03 ml.kg−1.min−1). Furthermore, the models demonstrated moderate validity, as evidenced by an intraclass correlation coefficient (ICC) of 0.841 and a coefficient of variation averaging 10.9%, with a range from 8.5% to 13.6%. Conclusions: While Jackson’s two non-exercise models showed limited accuracy in predicting VO2max among Iranian healthy male adults, they exhibited reasonable precision, particularly among moderately active men.

Concurrent and Aerobic Exercise on Maximal Oxygen Consumption in Adults with Obesity: Study Protocol for a Randomized Controlled Trial

Background. Concurrent and aerobic physical exercise are strategies for treating overweight and obesity. Most interventions have utilized cardiovascular or guided execution machines, which often involve high-cost materials not easily accessible to the general population. Objective. Identify the effect of 12 weeks of exercise (concurrent vs. aerobic training) based on the polarized training intensity distribution model on maximal oxygen consumption, muscle strength, and body composition. Materials and methods. A randomized controlled trial with two groups, concurrent vs. aerobic training (n = 28), in overweight and obese individuals. Both groups will perform 36 sessions, 3 times a week, on alternate days. Results. Current evidence has not demonstrated the superiority of concurrent over aerobic exercise on VO2max, muscle strength, and body composition. Additionally, the few randomized studies with concurrent exercise and the methodological limitations in their designs justify the importance of comparing both types of exercise to determine the best strategies for overweight and obese individuals regarding the mentioned outcomes.

Comparative effectiveness of exercise on cardiorespiratory function or exercise efficiency after stroke: A network meta-analysis of randomized control trials.

The network meta-analysis (NMA) was to compare and rank the effectiveness of different exercises on cardiorespiratory function or exercise efficiency in post-stroke patients. A NMA of randomized controlled trials (RCTs) was conducted. PubMed, Embase, Cochrane Library, and Web of Science were searched. The impact of exercises including individual and combination of aerobic exercise (AE), resistance exercise (RE), task-oriented training (TOT), gait training (GT), breathing exercise (BE), and regular rehabilitation training (RRT) on 6-min walk test (6MWT), peak oxygen consumption (VO2peak), maximum oxygen consumption (VO2max), resting heart rate (HRrest), resting systolic blood pressure (SBPrest), and resting diastolic blood pressure (DBPrest) were assessed. In total, 36 studies were included in the meta-analysis. AEGT (AE + GT) (63.06%) had the highest likelihood of improving 6MWT performance in post-stroke patients. RRTRE (RRT + RE) was the most favourable exercise in terms of 6MWT performance assessing by minimum clinically significant difference (MCID). AERE (AE + RE) had the highest likelihood of improving VO2peak and reducing HRrest in post-stroke patients. Different types of exercise demonstrated the benefits of improving cardiorespiratory function in stroke patients. Further research is needed to determine the best exercise regimen to maximize the benefits of rehabilitation interventions for post-stroke patients.

Reassembling the Field-based Applicability of the Lactate Threshold for Old Age.

This study aimed to investigate the applicability of the Lactate Threshold (LT) to predict maximal oxygen uptake (˙VO2max) and demarcate the boundary between the moderate- to heavy-intensity domain (HRm-h) in old age in comparison to the most utilized methods. A cross-sectional validation study was conducted. Participants aged 61 to 77 performed a familiarization procedure, an incremental maximal exercise treadmill test (CPX) for ˙VO2max determination, the Six-minute Walk Test (6MWT), and a discontinuous incremental field test for LT determination. Lower (P<0.01) internal effort was required for LT testing (76±8%HRmax) compared to 6MWT (92±9%HRmax). The application of the 6MWT reference equations overestimated ˙VO2max by 10-23%. LTs better estimated the ˙VO2max (r ≈0.90, SEE: ≈3.0] compared to the 6MWT (r=0.68, SEE=5.5). HRm-h determined by the CPX differed (20%; P=0.001) from that obtained by LT. HRm-h stratification indicated participants fall into the very light to the vigorous intensity domains. LT testing is more submaximal than the 6MWT, and is a valuable tool to estimate the ˙VO2max in older male adults. Implementation of LT testing in physical activity programs might help improving the quality of aerobic exercise training in older men.

Physical enhancement of older adults using hyperbaric oxygen: a randomized controlled trial

IntroductionAging is associated with a progressive decline in the capacity for physical activity. The objective of the current study was to evaluate the effect of an intermittent hyperbaric oxygen therapy (HBOT) protocol on maximal physical performance and cardiac perfusion in sedentary older adults.MethodsA randomized controlled clinical trial randomized 63 adults (> 64yrs) either to HBOT (n = 30) or control arms (n = 33) for three months. Primary endpoint included the maximal oxygen consumption (VO2Max) and VO2Max/Kg, on an E100 cycle ergometer. Secondary endpoints included cardiac perfusion, evaluated by magnetic resonance imaging and pulmonary function. The HBOT protocol comprised of 60 sessions administered on a daily basis, for 12 consecutive weeks, breathing 100% oxygen at 2 absolute atmospheres (ATA) for 90 min with 5-minute air breaks every 20 min.ResultsFollowing HBOT, improvements were observed in VO2Max/kg, with a significant increase of 1.91 ± 3.29 ml/kg/min indicated by a net effect size of 0.455 (p = 0.0034). Additionally, oxygen consumption measured at the first ventilatory threshold (VO2VT1) showed a significant increase by 160.03 ± 155.35 ml/min (p < 0.001) with a net effect size of 0.617. Furthermore, both cardiac blood flow (MBF) and cardiac blood volume (MBV) exhibited significant increases when compared to the control group. The net effect size for MBF was large at 0.797 (p = 0.008), while the net effect size for MBV was even larger at 0.896 (p = 0.009).ConclusionThe findings of the study indicate that HBOT has the potential to improve physical performance in aging adults. The enhancements observed encompass improvements in key factors including VO2Max, and VO2VT1. An important mechanism contributing to these improvements is the heightened cardiac perfusion induced by HBOT.Trial registrationClinicalTrials.gov Identifier NCT02790541 (registration date 06/06/2016).

Impaired Cardiac Sympathetic Activity Is Associated With Myocardial Remodeling and Established Biomarkers of Heart Failure.

123Iodine-meta-iodobenzylguanidine scintigraphy is useful for assessing cardiac autonomic dysfunction and predict outcomes in heart failure (HF). The relationship of cardiac sympathetic function with myocardial remodeling and diffuse fibrosis remains largely unknown. We aimed to evaluate the cardiac sympathetic function of patients with HF and its relation with myocardial remodeling and exercise capacity. Prospectively enrolled patients with HF (New York Heart Association class II-III) were stratified into HF with preserved left ventricular ejection fraction [LVEF] ≥45%) and reduced LVEF. Ventricular morphology/function and myocardial extracellular volume (ECV) fraction were quantified by cardiovascular magnetic resonance, global longitudinal strain by echocardiography, cardiac sympathetic function by heart-to-mediastinum ratio from 123iodine-meta-iodobenzylguanidine scintigraphy. All participants underwent cardiopulmonary exercise testing. The cohort included 33 patients with HF with preserved LVEF (LVEF, 60±10%; NT-proBNP [N-terminal pro-B-type natriuretic peptide], 248 [interquartile range, 79-574] pg/dL), 28 with HF with reduced LVEF (LVEF, 30±9%; NT-proBNP, 743 [interquartile range, 250-2054] pg/dL) and 20 controls (LVEF, 65±5%; NT-proBNP, 40 [interquartile range, 19-50] pg/dL). Delayed (4 hours) 123iodine-meta-iodobenzylguanidine heart-to-mediastinum ratio was lower in HF with preserved LVEF (1.59±0.25) and HF with reduced LVEF (1.45±0.16) versus controls (1.92±0.24; P<0.001), and correlated negatively with diffuse fibrosis assessed by ECV (R=-0.34, P<0.01). ECV in segments without LGE was increased in HF with preserved ejection fraction (0.32±0.05%) and HF with reduced left ventricular ejection fraction (0.31±0.04%) versus controls (0.28±0.04, P<0.05) and was associated with the age- and sex-adjusted maximum oxygen consumption (peak oxygen consumption); (R=-0.41, P<0.01). Preliminary analysis indicates that cardiac sympathetic function might potentially act as a mediator in the association between ECV and NT-proBNP levels. Abnormally low cardiac sympathetic function in patients with HF with reduced and preserved LVEF is associated with extracellular volume expansion and decreased cardiopulmonary functional capacity.

Effects of acute beetroot juice intake on performance, maximal oxygen uptake, and ventilatory efficiency in well-trained master rowers: a randomized, double-blinded crossover study.

Beetroot juice (BRJ) intake has been considered a practical nutritional strategy among well-trained athletes. This study aimed to assess the effects of BRJ intake on performance, cardiorespiratory and metabolic variables during a simulated 2000-meter rowing ergometer test in well-trained master rowers. Ten well-trained male master rowers (30-48 years) participated in a randomized, double-blind, crossover design for 3 weeks. In the first week, a researcher explained all the experimental procedures to the participants. In the next two weeks, the participants were tested in 2 rowing ergometer sessions, separated from each other by a 7-day washout period. In both strictly identical sessions, the participants randomly drank BRJ or placebo (PL) 3 hours before the start of the tests. Subsequently, the participants carried out the 2000-meter rowing ergometer tests. Oxygen saturation and blood lactate measurements were performed before starting (pretest) and at the end of the test (posttest). Performance parameters and cardiorespiratory variables were recorded during the rowing ergometer test. An improvement in time trial performance was observed, with a mean difference of 4 seconds (90% confidence limits ± 3.10; p ≤ 0.05) compared to PL. Relative and absolute increased (mean difference of 2.10 mL·kg-1·min-1, 90% confidence limits ± 1.80; mean difference of 0.16 L·min-1 90% confidence limits ± 0.11, respectively; p ≤ 0.05) compared to PL. No ergogenic effect was observed on ventilatory efficiency and blood lactate concentrations after BRJ intake. Acute BRJ intake may improve time trial performance as well as in well-trained master rowers. However, BRJ does not appear to improve ventilatory efficiency.

CA125 outperforms NT-proBNP in the prediction of maximum aerobic capacity in heart failure with preserved ejection fraction and kidney dysfunction.

Heart failure with preserved ejection fraction (HFpEF) often coexists with chronic kidney disease (CKD). Exercise intolerance is a major determinant of quality of life and morbidity in both scenarios. We aimed to evaluate the associations between N-terminal pro-B-type natriuretic peptide (NT-proBNP) and carbohydrate antigen 125 (CA125) with maximal aerobic capacity (peak VO2) in ambulatory HFpEF and whether these associations were influenced by kidney function. This single-centre study prospectively enrolled 133 patients with HFpEF who performed maximal cardiopulmonary exercise testing. Patients were stratified across estimated glomerular filtration rate (eGFR) categories (<60ml/min/1.73m2 versus ≥60ml/min/1.73m2). The mean age of the sample was 73.2±10.5years and 56.4% were female. The median of peak VO2 was 11.0ml/kg/min (interquartile range 9.0-13.0). A total of 67 (50.4%) patients had an eGFR <60ml/min/1.73m2. Those patients had higher levels of NT-proBNP and lower peak VO2, without differences in CA125. In the whole sample, NT-proBNP and CA125 were inversely correlated with peak VO2 (r=-0.43, P<.001 and r=-0.22, P=.010, respectively). After multivariate analysis, we found a differential association between NT-proBNP and peak VO2 across eGFR strata (P for interaction=.045). In patients with an eGFR ≥60ml/min/1.73m2, higher NT-proBNP identified patients with poorer maximal functional capacity. In individuals with eGFR <60ml/min/1.73m2, NT-proBNP was not significantly associated with peak VO2 [β=0.02 (95% confidence interval -0.19-0.23), P=.834]. Higher CA125 was linear and significantly associated with worse functional capacity without evidence of heterogeneity across eGFR strata (P for interaction=.620). In patients with stable HFpEF, NT-proBNP was not associated with maximal functional capacity when CKD was present. CA125 emerged as a useful biomarker for estimating effort intolerance in HFpEF irrespective of the presence of CKD.

The delta concept does not effectively normalise exercise responses to exhaustive interval training

ObjectivesThis study was designed to quantify inter- and intra-individual variability in performance, physiological, and perceptual responses to high-intensity interval training prescribed using the percentage of delta (%Δ) method, in which the gas exchange threshold and maximal oxygen uptake (V̇O2max) are taken into account to normalise relative exercise intensity. DesignRepeated-measures, within-subjects design with mixed-effects modelling. MethodsEighteen male and four female cyclists (age: 36 ± 12 years, height: 178 ± 10 cm, body mass: 75.2 ± 13.7 kg, V̇O2max: 51.6 ± 5.3 ml·kg−1·min−1) undertook an incremental test to exhaustion to determine the gas exchange threshold and V̇O2max as prescription benchmarks. On separate occasions, participants then completed four high-intensity interval training sessions of identical intensity (70 %Δ) and format (4-min on, 2-min off); all performed to exhaustion. Acute high-intensity interval training responses were modelled with participant as a random effect to provide estimates of inter- and intra-individual variability. ResultsGreater variability was generally observed at the between- compared with the within-individual level, ranging from 50 % to 89 % and from 11 % to 50 % of the total variability, respectively. For the group mean time to exhaustion of 20.3 min, inter- and intra-individual standard deviations reached 9.3 min (coefficient of variation = 46 %) and 4.5 min (coefficient of variation = 22 %), respectively. ConclusionsDue to the high variability observed, the %Δ method does not effectively normalise the relative intensity of exhaustive high-intensity interval training across individuals. The generally larger inter- versus intra-individual variability suggests that day-to-day biological fluctuations and/or measurement errors cannot explain the identified shortcoming of the method.

Effect of 6-Week Sprint Training on Long-Distance Running Performance in Highly Trained Runners.

Long-distance running performance has been reported to be associated with sprint performance in highly trained distance runners. Therefore, we hypothesized that sprint training could enhance distance running and sprint performance in long-distance runners. This study examined the effect of 6-week sprint training on long-distance running and sprint performance in highly trained distance runners. Nineteen college runners were divided into control (n = 8) and training (n = 11) groups. Participants in the training group performed 12 sprint training sessions in 6weeks, while those in the control group performed 12 distance training sessions. Before and after the interventions, maximal oxygen uptake (V˙O2max), O2 cost during submaximal running (290m·min-1 and 310m·min-1 of running velocity), and time to exhaustion (starting at 290m·min-1 and increased 10m·min-1 every minute) were assessed on a treadmill. Additionally, the 100-m and 400-m sprinting times and 3000-m running time were determined on an all-weather track. In the control group, no measurements significantly changed after the intervention. In the training group, the time to exhaustion, 100-m and 400-m sprinting times, and 3000-m running time improved significantly, while V˙O2max and O2 cost did not change. These results showed that 6-week sprint training improved both sprint and long-distance running performance in highly trained distance runners without a change in aerobic capacity. Improvement in the time to exhaustion without a change in V˙O2max suggests that the enhancement of long-distance running performance could be attributable to improved anaerobic capacity.

Detraining's Effects on Cardiorespiratory Fitness and Maximal and Explosive Strength in Army Soldiers: Does Age Matter?

This study investigated the impact of four weeks of age-dependent detraining on army soldiers' cardiorespiratory fitness and maximal and explosive strength. Fourteen volunteer tactical athletes participated, divided into two age groups (20 to 29 and 30 to 40 years). Before and after the detraining period, we assessed their anthropometric measurements (weight, height, body mass index, fat mass, and fat-free mass), cardiorespiratory fitness (maximal oxygen uptake [VO2max] and ventilatory thresholds [VT1 and VT2]), and kinematic properties during a single-leg counter-moving jump (CMJ) test for both the dominant and non-dominant legs. Two-way ANOVA followed by the Holm-Sidak post hoc test was used. The anthropometric and cardiovascular variables did not show significant differences between the groups. However, both groups exhibited a significantly reduced maximum time and speed at the VO2max. Furthermore, the flight time and maximum height during the CMJ significantly decreased in the non-dominant leg for both age groups. Notably, the dominant leg's concentric impulse (CI) significantly reduced during the CMJ, but this effect was observed only in the 30-40 age group. There were significant differences between the two age groups. Our findings suggest that four weeks of detraining negatively impacts aerobic fitness and muscular strength, independently of age. However, the dominant leg may be more susceptible to detraining effects in army soldiers aged 30-40. Furthermore, as a perspective, our results strongly suggest that a detraining period could affect successful missions (aerobic performance deterioration), as well as promote a muscle imbalance between the legs, which could encourage muscle injuries and endanger combat missions.

Exploring the correlation of skin temperature and body composition in athletes undergoing exhaustive physical exercise

During strenuous exercise, skin temperature (Tsk) plays an essential role in thermoregulatory processes. As indicated in the literature, its response might be influenced by body composition, among other factors. Hence, the objectives of this investigation were to determine whether there is a correlation between selected body components, specifically fat tissue and muscle tissue, and Tsk during graded exercise and recovery in athletes, and to identify which body component exhibits the strongest correlation with Tsk.Participants were grouped according to their aerobic capacity (VO2max/kg). A significant main effect was observed for the test stages (p < .001, η2 = 0.71), with Tsk decreasing from the start of the exercise, significantly decreasing at 12 km/h−1 (p < .001), and then increasing after exercise, especially within the first 5 min of recovery. Weak and non-significant effect for group/stage interaction was detected (p = .374, η2 = 0.03). A significant negative correlation was found between Tsk and both total tissue fat [%] (−0.51 < r < −0.63, p < .001) and lower limb tissue fat [%] (−0.50 < r < −0.71, p < .001) across all test stages. The correlation between Tsk and BMI was inconsistent, appearing only during the first stage of exercise and throughout recovery. No correlation was observed between Tsk and skeletal muscle mass, appendicular lean soft tissue, or relative skeletal muscle index.Endurance running to exhaustion leads to a progressive decrease in the Tsk of the lower extremity, followed by rewarming during recovery. The observed inverse correlation between adipose tissue and Tsk, along with the distinct temperature trends in groups with varying levels of fat tissue, could imply that the skin and subcutaneous tissue complex may play a more intricate role in thermal energy exchange beyond its insulating function. This implies a multifaceted involvement of these tissues in thermoregulation.

Phase angle is not influenced by hydration status after an aerobic session in recreational runners

Objective: Phase angle (PhA) has been proposed to be an indicator of muscle membrane integrity, which is useful for the evaluation of exercise-induced muscle soreness. PhA is derived from the bioimpedance analysis, which requires the participants to refrain from exercises prior to the evaluation. However, there are no studies in the literature regarding the effect of exercise-induced dehydration on the PhA analysis. This study aimed to compare the PhA after a running exercise session with and without hydration in recreational runners. Methods:14 male recreational runners (18-40 years old, VO2 max 51.08 ± 5.83 ml/min/kg) underwent a time-to-exhaustion running test in two conditions (with and without hydration). Mineral water was used in the hydration protocol. PhA and anthropometry were evaluated before and 1h after the time-to-exhaustion running tests. Results: There was no significant difference in body mass when comparing no hydration vs hydration protocols (1.4 ± 0.1 kg vs 0.7 ± 0.2 kg, respectively; p = 0.06). No significant difference between the procedures for the PhA of the right leg (7.89 ± 0.83 vs 7.82 ± 0+80; p = 0.15) and PhA of the left leg (7.86 ± 0.96 vs 8.07 ± 0.85 p = 1.00) were observed. Conclusion: The results indicated that the PhA is not influenced by exercise-induced dehydration when the water loss is approximately 2% of the body mass.

Design validity of interval and plyometric training programs for simultaneous increases in VO2 max, reactive agility, power in basketball: Aiken validity

Design validity of interval and plyometric training programs for simultaneous increases in VO2 max, reactive agility, power in basketball: Aiken validity

The effect of different breathing conditions on cerebral blood flow in young males during maximal aerobic exercise: A pilot study

BackgroundDuring aerobic exercise, cerebral blood flow (CBF) decreases past 70 % of maximal oxygen uptake (VO2), but transient hypercapnia could mitigate the reduction. AimsTo examine the effect of oral (OB), nasal (NB), and combined (CB) breathing on CBF during a graded maximal exercise test (GXT). MethodsSix young males (age: 21.8 ± 2.3 years) performed three GXTs until volitional fatigue using a randomized breathing condition (OB, NB, or CB) order. Respiratory gases were assessed via a metabolic cart. Ultrasound sonography (7.5 MHz linear transducer) was utilized to assess the peak systolic velocity (PSV), end-diastolic velocity (EDV), and vessel diameter of the internal (ICA) and external (ECA) carotid artery. A one-way ANCOVA, with VO2 as a covariate, followed by a Bonferroni post-hoc analysis, was utilized to examine the differences between the breathing conditions. ResultsThe end-tidal partial pressure of CO2 (PetCO2) was significantly greater (p = 0.006) during NB (33.16 ± 1.37 mmHg) than that of CB (26.63 ± 1.32 mmHg) and OB (26.72 ± 1.37) at 100 % VO2max. There was a trend of a greater PSV in the ICA throughout the entire GXT that was only significantly greater (p = 0.027) during NB (126.12 ± 7.51 cm/s) compared to OB (92.47 ± 7.34 cm/s) but not CB (111.91 ± 7.14 cm/s) at 70 % VO2max. ConclusionsDuring a GXT, NB demonstrated a superior capacity to increase CBF, denoted by a higher PSV in the ICA compared to CB and OB, which might be partly related to an increased PetCO2.

Norwegian male U14 soccer players have superior running capacity compared to Icelandic players.

The organisation and development strategies of youth soccer differ between Norway and Iceland. Whether this affect physical capacity is unknown. Thus, the first aim of the present study is to compare physical capacity between players from Iceland and Norway. Secondary aim is to assess associations between biological maturity and physical capacity in the Icelandic players since an association previously has been shown among the Norwegians. There were 48 U14 players from Iceland included and 103 players from Norway. Bone age (BA), measured with left-wrist x-ray, was used as an indicator of biological maturity. To measure physical capacity, 40 metre (m) linear sprint, standing long jump (SLJ), countermovement jump (CMJ), the Yo-Yo intermittent recovery test (IR1-test) and a maximal oxygen uptake test (VO2max) were used. Training load was assessed by questionnaire. The results showed that the Norwegian players ran faster (5.90 ± 0.38 vs. 6.37 ± 0.44 s, p < .001), had better intermittent endurance capacity (1,235 ± 461 vs. 960 ± 423 m, p < .001) and higher VO2max, (60.3 ± 6.5 vs. 54.8 ± 5.3 ml·kg-1·min-1, p < .001) than the Icelandic players. The players from Norway reported a higher number of weekly organised soccer training hours than the Icelandic. We also found significant correlations between BA and performance on 40 m linear sprint (r = -.566, p < .001), SLJ (r = .380, p = .008) and CMJ (r = .354, p = .014) among the Icelandic players. Moreover, no correlations were found between BA and VO2max or intermittent endurance capacity. In conclusion, the Norwegian players ran faster and had better VO2max and intermittent endurance capacity than the Icelandic players. Biological maturity level was associated with speed and jumping performance in U14 soccer players in Iceland, but not with VO2max or intermittent endurance capacity. Findings indicate that more research is needed to investigate the influence of different organisation and structure of youth soccer between the two countries on physical capacity.

Effects of various extract drinks on endurance in long-distance running training

This paper briefly introduces plant extracts and their combinations with sports drinks. The research involved 40 sportsmen who are affiliated with the Track and Field Department of the School of Physical Education in South-Central Minzu University. This paper aimed to explore the influence of sports drinks enhanced with extracts of Codonopsis pilosula and Acanthopanax senticosus on the endurance levels of long-distance runners. The participants were divided into four groups: a placebo group, a group receiving only C. pilosula, a group receiving A. senticosus, and a composite group. Endurance performance indices for long-distance running were evaluated both before and after the training. Before training, the heart rate, blood lactate level, and maximum oxygen uptake of the placebo group were 159.53 ± 2.21 times/min, 9.7 ± 1.2 mmol/L, and 66.18 ± 2.35 mL/kg/min, respectively; the single Codonopsis pilosula group was 158.33 ± 2.24 times/min, 9.6 ± 1.1 mmol/L, and 65.87 ± 1.88 mL/kg/min, respectively; the single Acanthopanax senticosus group was 159.66 ± 3.67 times/min, 9.7 ±1.0 mmol/L, and 66.32 ± 1.47 mL/kg/min, respectively; the Codonopsis pilosulae and Acanthopanax senticosus composite group was 158.21 ± 1.28 times/min, 9.6 ± 0.9 mmol/L, and 66.87 ± 1.12 mL/kg/min, respectively. After training, the corresponding values of the placebo group were 162.53 ± 3.21 times/min, 9.6 ± 0.8 mmol/L, and 68.85 ± 3.25 mL/kg/min, respectively; the single Codonopsis pilosula group was 145.33 ± 2.25 times/min, 9.1 ± 0.5 mmol/L, and 73.69 ± 2.58 mL/kg/min, respectively; the single Acanthopanax senticosus group was 142.66 ± 3.69 times/min, 9.1 ± 0.8 mmol/L, and 73.84 ± 2.19 mL/kg/min, respectively; the composite group was 131.21 ± 1.36 times/min, 8.3 ± 0.3 mmol/L, and 77.19 ± 3.14 mL/kg/min, respectively. Sports drinks that include extracts of C. pilosula and A. senticosus significantly increased endurance levels. The concurrent use of C. pilosula and A. senticosus was more beneficial in enhancing endurance performance for long-distance running in comparison to using each extract individually.

Physiological, Perceptual, and Biomechanical Responses to Load Carriage While Walking at Military-Relevant Speeds and Loads—Are There Differences between Males and Females?

This study aimed to investigate the physiological, perceptual, and biomechanical differences between male and female soldiers across several military-relevant load and walking speed combinations. Eleven female and twelve male soldiers completed twelve 12 min walking trials at varying speeds (3.5 km·h−1, 5.5 km·h−1, 6.5 km·h−1) and with varying external loads (7.2 kg, 23.2 kg, 35.2 kg). Physiological (indirect calorimetry, heart rate), perceptual (perceived exertion), and biomechanical (spatiotemporal, kinematic, kinetic) outcomes were measured throughout each trial. Females had a lower aerobic capacity and lower body strength than males, which resulted in them working at a greater exercise intensity (%VO2peak and heart rate) but with a lower oxygen pulse. Females demonstrated higher breathing frequency and perceived exertion with specific loads. At selected loads and speeds, frontal and sagittal pelvis, hip, and knee motions and forces were greater for females. Females consistently displayed greater relative stride length and step width. In conclusion, this study demonstrates the importance of tailored interventions, periodisation, and nutritional strategies for female military personnel, given their higher relative work rate and increased injury risk during load carriage tasks. Understanding these differences is crucial for preparing female soldiers for the physical demands of military service.