O2 Max Research Articles

Ventilatory and Perceived Ergogenic Effects of Mandibular Forward Repositioning During Running at Maximal Oxygen Uptake Intensity.

Cardoso, F, Costa, MJ, Colaço, P, Vilas-Boas, JP, Pinho, JC, Pyne, DB, and Fernandes, RJ. Ventilatory and perceived ergogenic effects of mandibular forward repositioning during running at maximal oxygen uptake intensity. J Strength Cond Res XX(X): 000-000, 2024-Wearing an intraoral dental splint may enhance ventilatory function and exercise performance. Nineteen runners performed on a 400-m outdoor track: (a) an incremental protocol to assess the velocity at maximal oxygen uptake (vV̇ o2 max) and (b) 2 square wave bouts wearing 2 intraoral splints (with and without mandibular forward repositioning). The time until exhaustion at vV̇ o2 max (TLimv V̇ o2 max), ventilatory variables, oxygen uptake (V̇ o2 ) kinetics, energetic profiling, perceived exertion and kinematics, were all measured. Ventilatory data were assessed breath-by-breath and perceived exertion evaluated using the Borg 6-20-point scale at the end of TLimv V̇ o2 max bouts. Images were recorded by video cameras (120 Hz) and kinematic measures retrieved using Kinovea. A paired t test was computed for comparison of splints ( p ≤ 0.05). With (vs. without) mandibular forward repositioning, runners increased their TLimv V̇ o2 max by ∼6% ( p = 0.03), coupled with higher ventilation (151 ± 22 vs. 147 ± 23 L·min -1 , p = 0.04), end-tidal oxygen tension (114.3 ± 3.7 vs. 112.9 ± 3.9 mm Hg, p = 0.003), and lower inspiratory time (0.526 ± 0.083 vs. 0.540 ± 0.090 seconds, p = 0.02), despite similar V̇ o2 kinetics (e.g., 49.0 ± 8.7 vs. 47.7 ± 8.6 ml∙kg∙min -1 of fast component amplitude) being observed. The energy expenditure was ∼8% higher ( p = 0.03) with the mandible forward, coupled with lower perceived exertion scores ( p = 0.04). Mandibular forward repositioning was effective in acutely improving running performance at vV̇ o2 max with ergogenic effects on ventilatory and perceived variables.

Re-evaluating the Need for Routine Maximal Aerobic Capacity Testing within Fighter Pilots.

INTRODUCTION: There is a current belief in aviation suggesting that aerobic training may reduce G-tolerance due to potential negative impacts on arterial pressure response. Studies indicate that increasing maximal aerobic capacity (<mml:math id="ie1" display="inline"><mml:mrow><mml:mover><mml:mtext>V</mml:mtext><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math>o₂ max) through aerobic training does not hinder G-tolerance. Moreover, sustained centrifuge training programs revealed no instances where excessive aerobic exercise compromised a trainee's ability to complete target profiles. The purpose of this review article is to examine the current research in the hope of establishing the need for routine <mml:math id="ie2" display="inline"><mml:mrow><mml:mover><mml:mtext>V</mml:mtext><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math>o₂-max testing in air force pilot protocols.METHODS: A systematic search of electronic databases including Google Scholar, PubMed, the Aerospace Medical Association, and Military Medicine was conducted. Keywords related to "human performance," "Air Force fighter pilots," "aerobic function," and "maximal aerobic capacity" were used in various combinations. Articles addressing exercise physiology, G-tolerance, physical training, and fighter pilot maneuvers related to human performance were considered. No primary data collection involving human subjects was conducted; therefore, ethical approval was not required.RESULTS: The <mml:math id="ie3" display="inline"><mml:mrow><mml:mover><mml:mtext>V</mml:mtext><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math>o₂-max test provides essential information regarding a pilot's ability to handle increased Gz-load. It assists in predicting G-induced loss of consciousness by assessing anti-G straining maneuver performance and heart rate variables during increased G-load.DISCUSSION: <mml:math id="ie4" display="inline"><mml:mrow><mml:mover><mml:mtext>V</mml:mtext><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math>o₂-max testing guides tailored exercise plans, optimizes cardiovascular health, and disproves the notion that aerobic training hampers G-tolerance. Its inclusion in air force protocols could boost readiness, reduce health risks, and refine training for fighter pilots' safety and performance. This evidence-backed approach supports integrating <mml:math id="ie5" display="inline"><mml:mrow><mml:mover><mml:mtext>V</mml:mtext><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math>o₂-max testing for insights into fitness, risks, and tailored exercise.Zeigler Z, Acevedo AM. Re-evaluating the need for routine maximal aerobic capacity testing within fighter pilots. Aerosp Med Hum Perform. 2024; 95(5):273-277.

Five-Week, Low-Intensity Blood Flow Restriction Rowing Improves V̇ o2 max in Elite Rowers.

Held, S, Rappelt, L, Rein, R, Deutsch, J-P, Wiedenmann, T, and Donath, L. Five-week, low-intensity, blood flow restriction rowing improves V̇ o2 max in elite rowers. J Strength Cond Res 38(6): e299-e303, 2024-This controlled intervention study examined the effects of low-intensity rowing with blood flow restriction (BFR) on maximal oxygen uptake (V̇ o2 max), peak power output during ramp testing (PPO), and 2000-m time trial performance (P2k). Eleven, highly elite, male rowers (22.1 ± 1.6 years; 92.6 ± 3.8 kg; 1.93 ± 0.04 m; 7.9. ± 2.2 years rowing experience; 20.4 ± 2.0 h·w -1 training volume; 11.9 ± 1.1 session per week) trained 5 weeks without BFR (Base) followed by a 5-week BFR intervention period. BFR of the lower limb was applied through customized elastic wraps. BFR took place 3 times a week (accumulated net pBFR: 60 min·wk -1 ; occlusion per session: 2 times 10 min·session -1 ) and was used exclusively at low intensities (<2 mmol·L -1 ). V̇ o2 max, PPO, and P2k were examined before, between, and after both intervention periods. Bayesian's credible intervals revealed relevantly increased V̇ o2 max +0.30 L·min -1 (95% credible interval: +0.00 to +0.61 L·min -1 ) adaptations through BFR. By contrast, PPO +14 W (-6 to +34 W) and P2k -5 W (-14 to +3 W) were not noticeably affected by the BFR intervention. This study revealed that 15 sessions of BFR application with a cumulative total BFR load of 5 h over a 5-week macrocycle increased V̇ o2 max remarkably. Thus, pBFR might serve as a promising tool to improve aerobic capacity in highly trained elite rowers.

Power, Endurance, and Body Composition Changes Over a Collegiate Career in National Collegiate Athletic Association Division I Women Soccer Athletes.

McFadden, BA, Bozzini, BN, Cintineo, HP, Hills, SP, Walker, AJ, Chandler, AJ, Sanders, DJ, Russell, M, and Arent, SM. Power, endurance, and body composition changes over a collegiate career in National Collegiate Athletic Association Division I women soccer athletes. J Strength Cond Res 37(7): 1428-1433, 2023-The purpose of this study was to determine longitudinal changes in fitness and body composition throughout athletes' 4-year collegiate soccer careers. Performance testing occurred before preseason during freshman, sophomore, junior, and senior year in 17 female Division I soccer players. Body composition was assessed through air-displacement plethysmography to determine percent body fat (%BF), fat-free mass (FFM), and body mass (BM). Maximal countermovement vertical jump height was assessed through contact mat using arm swing (CMJ AS ) and hands-on-hips (CMJ HOH ) methods to calculate power (CMJ watts / HOHwatts ). Aerobic capacity (V̇ o2 max) and ventilatory threshold (VT) were assessed by indirect calorimetry during a maximal graded exercise test on a treadmill. Linear mixed models were used to assess changes across academic years ( p < 0.05). No changes occurred in %BF, BM, V̇ o2 max, VT, CMJ AS , or CMJ watts . A time main effect was seen for FFM ( p = 0.01) with increases from freshman to senior ( p = 0.02). Time main effects were observed for CMJ HOH ( p < 0.001) and CMJ HOHwatts ( p < 0.001) with increases from freshman to junior (CMJ HOH,p = 0.001; CMJ HOHwatts , p = 0.02) and senior (CMJ HOH , p < 0.001; CMJ HOHwatts , p = 0.003) as well as sophomore to senior (CMJ HOH , p < 0.001; CMJ HOHwatts , p = 0.02). Countermovement vertical jump with hands on hips also increased from sophomore to junior ( p = 0.005). The lower FFM and power capabilities as freshmen compared with upperclassman indicate a potential limited readiness. Coaches and training staff should account for these developmental differences when entering the preseason. Adequate conditioning programs before starting a collegiate program may help build a fitness foundation and prepare freshmen athletes to compete at the same level as their upperclassmen counterparts.

Postexercise Arterial Compliance and Hemodynamic Responses to Various Durations and Intensities of Aerobic Exercise.

Karabulut, M, Bitting, M, and Bejar, J. Postexercise arterial compliance and hemodynamic responses to various durations and intensities of aerobic exercise. J Strength Cond Res 37(3): 589-596, 2023-The purpose of this study was to determine the effects of various aerobic training protocols using different intensities and durations on arterial compliance and hemodynamic responses. Seventeen male subjects (age = 23.1 ± 2.8 years) performed a maximal oxygen consumption (V̇ o2 max) test, followed by 3 randomly assigned exercise test sessions, each on a separate day. At the beginning of each test session, pre-exercise baseline assessments of arterial elasticity, hemodynamic variables, and pulse wave velocity (PWV) were performed after a 10-minute rest. After baseline measurements, participants performed either a bout of aerobic exercise on a treadmill for 60 minutes at 65% of V̇ o2 max (60min); 20 minutes at 40% of V̇ o2 max (20min); or for 20 minutes at 40% of V̇ o2 max with blood flow restriction (BFR; 20min-BFR). All baseline measurements were repeated at the completion of each testing session. Significance for this study was set at p ≤ 0.05. The 60min session resulted in significant increases in small artery elasticity (SAE) compared with the 20min-BFR session ( p < 0.03) and decreases in both systemic vascular resistance (SVR) and total vascular impedance (TVI) compared with both 20min sessions ( p < 0.01). The carotid to radial PWV was significantly lower after both the 60min and the 20min-BFR sessions compared with the 20min session ( p < 0.02). The findings indicate that the duration and the intensity of exercise are important factors for improving SAE, SVR, and TVI. In addition, 20min-BFR at 40% V̇ o2 max may result in site-specific modifications in PWV that is comparable with those seen after 60 minutes of exercise at 65% V̇ o2 max.

Sprint Interval Training Attenuates Neuromuscular Function and Vagal Reactivity Compared With High-Intensity Functional Training in Real-World Circumstances.

Benítez-Flores, S, de S. Castro, FA, Lusa Cadore, E, and Astorino, TA. Sprint interval training attenuates neuromuscular function and vagal reactivity compared with high-intensity functional training in real-world circumstances. J Strength Cond Res 37(5): 1070-1078, 2023-The aim of this study was to compare the acute cardiovascular and neuromuscular effects of 3 time-matched sessions of high-intensity training. Eighteen moderately active adults (9 women and 9 men [age: 23 ± 2.9 years; maximum oxygen consumption (V̇ o2 max): 47.6 ± 4.1 ml·kg -1 ·min -1 ]) performed three low-volume (∼9 minutes) sessions in a randomized order: sprint interval training (SIT), burpee interval training (BIT) (10 × 5 seconds efforts × 35 seconds recovery), and vigorous intensity continuous training (VICT) (6 minutes 5 seconds of running at ∼85% of peak heart rate [HR peak ]). Indices related to heart rate (HR), neuromuscular performance (counter movement jump height [CMJ height ] and squat and bench press power), and autonomic balance (heart rate recovery and heart rate variability [HRR and HRV] )were monitored during exercise. Sprint interval training and VICT elicited a higher HR mean (171.3 ± 8.4 and 166.5 ± 7.5 vs. 150.5 ± 13.6 b·min -1 , p < 0.001) and time of ≥90%HR peak (133.3 ± 117.4 and 110 ± 128.9 vs. 10 ± 42.4 seconds, p < 0.01) than BIT. Sprint interval training exhibited a slower HRR and lower HRV than BIT and VICT ( p < 0.05) postsession. Moreover, only SIT resulted in a significant decline ( p < 0.01) in CMJ height (34.7 ± 7.2 to 33.5 ± 7.2 cm), relative squat mean power (25.5 ± 4.5 to 23.8 ± 4.9 W·kg -1 ), and relative bench press peak power (6.9 ± 2.4 to 6.2 ± 2.5 W·kg -1 ). Results revealed that SIT diminishes the sympathovagal reactivation and neuromuscular performance compared with work-matched BIT and VICT.

Preexercise High-Fat Meal Following Carbohydrate Loading Attenuates Glycogen Utilization During Endurance Exercise in Male Recreational Runners.

Iwayama, K, Tanabe, Y, Yajima, K, Tanji, F, Onishi, T, and Takahashi, H. Preexercise high-fat meal following carbohydrate loading attenuates glycogen utilization during endurance exercise in male recreational runners. J Strength Cond Res 37(3): 661-668, 2023-This study aimed to investigate whether one preexercise high-fat meal can increase glycogen conservation during endurance exercise, as compared with one preexercise high-carbohydrate meal. Ten young male recreational runners (22.0 ± 0.6 years; 171.3 ± 0.9 cm; 58.3 ± 1.9 kg; maximal oxygen uptake [V̇ o2 max], 62.0 ± 1.6 ml·kg -1 ·min -1 ) completed 2 exercise trials after high-carbohydrate loading: eating a high-carbohydrate (CHO; 7% protein, 13% fat, 80% carbohydrate) meal or eating a high-fat (FAT; 7% protein, 42% fat, 52% carbohydrate) meal 3.5 hours before exercise. The order of the 2 trials was randomized, and the interval between trials was at least 1 week. The experimental exercise consisted of running on a treadmill for 60 minutes at 95% of each subject's lactate threshold. Muscle and liver glycogen content were assessed using noninvasive carbon magnetic resonance spectroscopy before the experimental meal as well as before and after exercise; respiratory gases were measured continuously during exercise. The respiratory exchange ratio during exercise was statistically lower in the FAT trial than in the CHO trial ( p < 0.01). In addition, muscle ( p < 0.05) and liver ( p < 0.05) glycogen utilization during exercise was less in the FAT trial than in the CHO trial. Therefore, one high-fat meal following carbohydrate loading reduced muscle and liver glycogen use during the 60-minute exercise. These results suggest that this dietary approach may be applied as a strategy to optimize energy utilization during endurance exercise.

Cardiorespiratory Fitness and Neuromuscular Function of Mechanically Ventilated ICU COVID-19 Patients.

The aim of the current study was to investigate the level of cardiorespiratory fitness and neuromuscular function of ICU survivors after COVID-19 and to examine whether these outcomes are related to ICU stay/mechanical ventilation duration. Prospective nonrandomized study. Patients hospitalized in ICU for COVID-19 infection. Sixty patients hospitalized in ICU (mean duration: 31.9 ± 18.2 d) were recruited 4-8 weeks post discharge from ICU. None. Patients visited the laboratory on two separate occasions. The first visit was dedicated to quality of life questionnaire, cardiopulmonary exercise testing, whereas measurements of the knee extensors neuromuscular function were performed in the second visit. Maximal oxygen uptake (V o2 max) was 18.3 ± 4.5 mL·min -1 ·kg -1 , representing 49% ± 12% of predicted value, and was significantly correlated with ICU stay/mechanical ventilation (MV) duration ( R = -0.337 to -0.446; p < 0.01 to 0.001), as were maximal voluntary contraction and electrically evoked peak twitch. V o2 max (either predicted or in mL· min -1 ·kg -1 ) was also significantly correlated with key indices of pulmonary function such as predicted forced vital capacity or predicted forced expiratory volume in 1 second ( R = 0.430-0.465; p ≤ 0.001) and neuromuscular function. Both cardiorespiratory fitness and neuromuscular function were correlated with self-reported physical functioning and general health status. V o2 max was on average only slightly above the 18 mL·min -1 ·kg -1 , that is, the cut-off value known to induce difficulty in performing daily tasks. Overall, although low physical capacities at admission in ICU COVID-19 patients cannot be ruled out to explain the association between V o2 max or neuromuscular function and ICU stay/MV duration, altered cardiorespiratory fitness and neuromuscular function observed in the present study may not be specific to COVID-19 disease but seem applicable to all ICU/MV patients of similar duration.

Longitudinal Changes in Health and Fitness Measures Among State Patrol Officers by Sex.

Dawes, JJ, Lopes dos Santos, M, Kornhauser, C, Holmes, RJ, Alvar, BA, Lockie, RG, and Orr, RM. Longitudinal changes in health and fitness measures among state patrol officers by sex. J Strength Cond Res 37(4): 881-886, 2023-Research suggests that police officers lose fitness as a result of their policing vocation with occupational factors like stress, shift work, poor sleep, and poor diet all contributors to this loss The purpose of this research was to measure changes in fitness test scores of qualified police officers over a 5-year period. Archived fitness data for 523 state patrol officers ( n = 494 men; 29 women) from one agency were used for this analysis. These tests included 60-second sit-up [SU] and push-up [PU] scores (muscular endurance), vertical jump height [VJ] (lower-body power), and 20-m multistage fitness test (aerobic capacity). A series of paired-samples t-tests and effect size calculations were used to investigate mean differences in fitness tests score at the beginning and end of a 5-year period. The paired-samples t test showed significant tests score decreases among male officers over the 5-year period in VJ, PU, and V̇ o2 max , , with no differences observed in SU performance. Small effect sizes were observed in both VJ ( g = -0.20) and PU ( g = -0.27) with a trivial effect size observed in changes to V̇ o2 max ( g = -0.14). In contrast, significant improvements in performance were observed in SU performance among female officers, with a small effect size ( g = 0.38). No other significant differences were found in female measures. Whether at an organizational or individual level, annual fitness assessments for police officers can serve to educate and motivate officers regarding their personal fitness and potentially slow the negative impact of aging on health, fitness, and performance in these populations.

Cold Stress Induced a Higher Level of Fat Oxidation in Women.

Niu, X, Han, P, Tang, Z, Huang, J, Li, L, He, H, Zhang, W, Zhao, L, and Zhao, L. Cold stress induced a higher level of fat oxidation in women. J Strength Cond Res 37(1): 114-122, 2023-To investigate women's fat oxidation under cold stress during incremental exercise testing and compare the effect of cold stress on fat oxidation between the sexes. Twenty-six healthy subjects performed 2 incremental exercise tests to determine maximal oxygen uptake (V̇ o2 max) on a treadmill in different ambient temperatures. Cardiopulmonary variables were continuously recorded during incremental exercise tests. Maximal fat oxidation (MFO) and the corresponding exercise intensity (Fat max ) were determined from the fat oxidation curve constructed by indirect calorimetry. Both men and women relied more on fat oxidation in cold environment ( p < 0.05). Compared with men, fat oxidation was significantly greater in women in the cold environment from 50 to 70% V̇ o2 max ( p < 0.05). There were no significant differences in the change of fat oxidation as exercise intensity increased between the sexes ( p > 0.05). Women had a greater MFO ( p < 0.05) and Fat max ( p < 0.05) than men in the cold environment. When MFO was the dependent variable, sex, fat-free mass, fat mass, V̇ o2 max, and temperature accounted for 48% of its variability. We conclude that cold stress enhances fat oxidation in women. Compared with men, women have significantly higher value and rely more on fat oxidation to supply energy in the cold environment, although the increasing level of fat oxidation was similar between the sexes. These factors may have important implications in the individualization of exercise prescription in cold conditions for both men and women.

Strength, Cardiovascular Fitness, and Blood Lipid Measures in Law Enforcement Personnel After a 12-Week Health Promotion Program.

Hibbert, JE, Klawiter, DP, Schubert, MM, Nessler, JA, and Asakawa, DS. Strength, cardiovascular fitness, and blood lipid measures in law enforcement personnel after a 12-week health promotion program. J Strength Cond Res 36(11): 3105-3112, 2022-Law enforcement personnel often have high rates of cardiovascular disease and injury. Health promotion programs have been found to successfully encourage behavior change among law enforcement personnel, but these programs can often be intensive and expensive. Thus, the purpose of this study was to examine the efficacy of a health promotion program on body composition, metabolic health, muscle strength, and cardiovascular endurance in law enforcement personnel. Active duty officers from a local law enforcement agency were invited to participate in a 12-week health promotion program that included activity tracking and exercise and nutrition education. Eighteen subjects underwent measurements of body composition, V̇ o2 max through treadmill test, knee extensor strength, and blood lipids. An a priori alpha level for significance was set at 0.05, and comparisons were assessed using paired t -tests. Overall, subjects improved blood lipid levels evidenced by movement of mean values toward established healthy ranges. Although 8 subjects improved their V̇ o2 max (range: 1.3-30% change), there was large variability and no statistically significant differences in measures of V̇ o2 max (pre: 38.48 ± 5.86 ml·kg·min -1 ; post: 39.27 ± 5.26 ml·kg·min -1 ), body composition (pre: 26.52 ± 8.02% body fat; post: 26.44 ± 7.45% body fat), and strength normalized to body mass (isometric pre: 1.45 ± 0.45; post: 1.08 ± 0.36). Although no significant changes were noted, promising trends in these data suggest that health promotion programs with a modified focus may lead to positive changes in overall health.

Independent influence of age on heart rate recovery after flywheel exercise in trained men and women

The present study examined whether differences in the heart rate recovery following flywheel exercise cessation were associated with differences in maximal oxygen uptake ({dot{text{V}}}O2 max.), age and sex in trained adults. Eleven men (age range 22–49 years, {dot{text{V}}}O2 max. = 43.6 ± 7.6 mL kg min−1) and ten women (age range 20—53 years, {dot{text{V}}}O2 max. = 38.0 ± 5.7 mL kg min−1) were randomly assigned to complete a squat-exercise on the flywheel ergometer set at three different moments of inertia, while their cardiovascular responses were continuously monitored. During the flywheel exercise the mean arterial pressure rose by ~ 35 to 40% (p = .001), and the increment was more robust in men than women. The cardiac index was two-fold greater across both sexes compared to the baseline (p = .001), while the rise in heart rate (~ 144 bpm) was more pronounced in women to compensate for their load-dependent stroke index decline (p = .001). The load-independent time-course changes in heart rate recovery markers were comparable between the sexes. When these indicators were pooled, a stepwise regression revealed age as the only relevant predictor of both fast and slow components of the heart rate recovery (~ 30% of the shared variance explained, p = .014). The present data suggest that the heart rate recovery declines with age, irrespective of sex, or well-preserved cardiorespiratory fitness in moderately-trained adults.

Talent Development in Young Cross-Country Skiers: Longitudinal Analysis of Anthropometric and Physiological Characteristics.

Introduction: Very little is known about talent development and selection processes in young cross-country skiers.Aim: (1) to analyze the effect of age on anthropometric and physiological parameters in medium-to-high level cross-country skiers during the late teenage period; (2) to describe parameters' trend in selected talents after the late teenage period; (3) to define which characteristics during the late teenage period could discriminate against further talent selection.Method: We found 14 male (M) and nine (F) athletes in our database, identified as talents by regional teams during the late teenage period, who performed the same diagonal-stride roller-skiing incremental test to exhaustion at 17 and 18 years old. Of these, four M and three F teenagers performed four further evaluations, and were selected by the national team. Age effect during the late teenage period was verified on anthropometric and physiological parameters measured at maximal intensity (MAX), first (VT1), and second (VT2) ventilatory thresholds, and 3° and 6° of treadmill incline. An observational analysis allowed to evaluate parameters' trend after the late teenage period in selected athletes, and to determine possible characteristics early discriminating further selection.Results: During the late teenage period, height, weight, and BMI was still raising in M as well as V'O2 at VT2 and 6° of treadmill incline (all P > 0.05). In F, mass-scaled V'O2 MAX increased while heart rate (HR) at MAX and VT2 decreased (all P > 0.05). Since the late teenage period, all selected males showed maximal ventilation volumes, absolute V'O2 at MAX, VT1, and VT2 that were within or above the 75th percentile of their group; the same was found in selected females for mass-scaled V'O2 MAX, VT1, and VT2 time. After the late teenage period, all selected athletes showed an increasing trend for VT2 time, while a decreasing trend for sub-maximal energetic cost, %V'O2 and HR.Discussion: During the late teenage period, males are still completing their maturation process. Since the late teenage period, some physiological parameters seem good indicators to early discriminate for further talents. A progressive increase in skiing efficiency was demonstrated in developing talents of both sexes after the late teenage period.

Effects of Nonperiodized and Linear Periodized Combined Training on Health-Related Physical Fitness in Adults With Obesity: A Randomized Controlled Trial.

Streb, AR, Passos da Silva, R, Leonel, LdS, Possamai, LT, Gerage, AM, Turnes, T, and Del Duca, GF. Effects of nonperiodized and linear periodized combined training on health-related physical fitness in adults with obesity: a randomized controlled trial. J Strength Cond Res 36(9): 2628-2634, 2022-The aim of this randomized controlled trial study was to compare the effects of 16 weeks of linear periodized and nonperiodized combined training (CT) in cardiorespiratory fitness, muscle strength, and body composition indicators of adults with obesity. Thirty-four obese adults of both sexes (36.6 ± 4.4 years; body mass index, 32.9 ± 2.7 kg·m -2 ) were divided into nonperiodized (NG; n = 8), linear periodized (PG; n = 11), and control (CG; n = 15) groups. The NG and PG groups performed 3 weekly sessions of CT over 16 weeks in different ways. Anthropometric measures, maximal strength for leg press and barbell bench press, maximal oxygen uptake (V̇ o2 max), and ventilatory thresholds were determined before and after intervention. The generalized estimation equation was used, with the applied level of significance for the interaction of 0.10 and the isolated effect of time or group or both of 0.05. Significant and similar increases were observed in the 1-repetition maximum test for bench press (NG: 48.8 ± 5.7 to 55.0 ± 6.1 kg; PG: 48.7 ± 5.7 to 53.8 ± 5.9 kg; p = 0.001) and leg press (NG: 235.2 ± 18.7 to 268.3 ± 19.7 kg; PG: 223.1 ± 25.3 to 253.3 ± 23.1 kg; p = 0.05) in trained groups. Relative V̇ o2 max improved only in PG (27.8 ± 1.3 to 32.0 ± 1.4 mL·kg·min -1 ; p = 0.05), while ventilatory thresholds improved in NG and CG ( p = 0.004 and p = 0.06). There was an increase in body mass in CG (97.6 ± 3.4 to 99.1 ± 2.9 kg) and NG (92.5 ± 5.4 to 93.5 ± 5.4 kg; p = 0.05). Combined training improved maximal upper-body and lower-body strength, regardless of periodization. However, for improvement in V̇ o2 max, linear periodization may be superior to nonperiodization in obese adults.

Normative Values for Health-Related Physical Fitness in First-Year Police Officers

Štefan, L, Kasović, M, and Culej, M. Normative values for health-related physical fitness in first-year police officers. J Strength Cond Res 36(9): 2530-2535, 2022-The main aim of the study was to develop normative values for health-related physical fitness tests in first-year police officers. In this cross-sectional study, we recruited 773 police officers aged 19-28 years old (mean age ± SD = 22 ± 3 years, 34% women). Health-related physical fitness included: (a) polygon backwards (agility), (b) standing broad jump (explosive power of lower extremities), (c) sit-and-reach test (flexibility), and (d) 2.4 km run (aerobic capacity). In addition, maximal oxygen uptake (V̇ o2 max) was calculated. Sex- and age-specific centile smoothed curves for the 20th, 40th, 60 th , and 80th percentiles using Cole's LMS method were created. The results showed that men performed better in all health-related physical fitness tests ( p < 0.001), compared with women. The median values for polygon backwards, standing broad jump, sit-and-reach test, 2.4 km run and V̇ o2 max were 8 seconds, 210, 15 cm, 721 seconds and 49 mlO 2 ·kg -1 ·min -1 in men and 10 seconds, 165, 10 cm, 915 seconds and 39 mlO 2 ·kg -1 ·min -1 in women. No significant interaction between age and health-related physical fitness was observed. This study provides sex- and age-specific normative values for health-related physical fitness in police officers. Findings from this study may be used in detecting a group of police officers who have lower levels of physical fitness. Thus, policies aiming to enhance the level of physical fitness could be implemented within the system.

Vascular ATP-sensitive K+ channels support maximal aerobic capacity and critical speed via convective and diffusive O2 transport.

Oral sulphonylureas, widely prescribed for diabetes, inhibit pancreatic ATP-sensitive K+ (KATP ) channels to increase insulin release. However, KATP channels are also located within vascular (endothelium and smooth muscle) and muscle (cardiac and skeletal) tissue. We evaluated left ventricular function at rest, maximal aerobic capacity ( O2 max) and submaximal exercise tolerance (i.e. speed-duration relationship) during treadmill running in rats, before and after systemic KATP channel inhibition via glibenclamide. Glibenclamide impaired critical speed proportionally more than O2 max but did not alter resting cardiac output. Vascular KATP channel function (topical glibenclamide superfused onto hindlimb skeletal muscle) resolved a decreased blood flow and interstitial PO2 during twitch contractions reflecting impaired O2 delivery-to-utilization matching. Our findings demonstrate that systemic KATP channel inhibition reduces O2 max and critical speed during treadmill running in rats due, in part, to impaired convective and diffusive O2 delivery, and thus O2 , especially within fast-twitch oxidative skeletal muscle. Vascular ATP-sensitive K+ (KATP ) channels support skeletal muscle blood flow and microvascular oxygen delivery-to-utilization matching during exercise. However, oral sulphonylurea treatment for diabetes inhibits pancreatic KATP channels to enhance insulin release. Herein we tested the hypotheses that: i) systemic KATP channel inhibition via glibenclamide (GLI; 10 mg kg-1 i.p.) would decrease cardiac output at rest (echocardiography), maximal aerobic capacity ( O2 max) and the speed-duration relationship (i.e. lower critical speed (CS)) during treadmill running; and ii) local KATP channel inhibition (5 mg kg-1 GLI superfusion) would decrease blood flow (15 µm microspheres), interstitial space oxygen pressures (PO2 is; phosphorescence quenching) and convective and diffusive O2 transport ( O2 and DO2 , respectively; Fick Principle and Law of Diffusion) in contracting fast-twitch oxidative mixed gastrocnemius muscle (MG: 9% type I+IIa fibres). At rest, GLI slowed left ventricular relaxation (2.11 ± 0.59 vs. 1.70 ± 0.23 cm s-1 ) and decreased heart rate (321 ± 23 vs. 304 ± 22 bpm, both P < 0.05) while cardiac output remained unaltered (219 ± 64 vs. 197 ± 39 ml min-1 , P > 0.05). During exercise, GLI reduced O2 max (71.5 ± 3.1 vs. 67.9 ± 4.8 ml kg-1 min-1 ) and CS (35.9 ± 2.4 vs. 31.9 ± 3.1 m min-1 , both P < 0.05). Local KATP channel inhibition decreased MG blood flow (52 ± 25 vs. 34 ± 13 ml min-1 100 g tissue-1 ) and PO2 isnadir (5.9 ± 0.9 vs. 4.7 ± 1.1 mmHg) during twitch contractions. Furthermore, MG O2 was reduced via impaired O2 and DO2 (P < 0.05 for each). Collectively, these data support that vascular KATP channels help sustain submaximal exercise tolerance in healthy rats. For patients taking sulfonylureas, KATP channel inhibition may exacerbate exercise intolerance.

Breathing resistance in metabolic systems: Its effects on pulmonary ventilation and oxygen uptake in elite athletes with high aerobic power

The aim of this study was to investigate the effects on pulmonary ventilation and oxygen uptake ( [Formula: see text]O2) in athletes with a very high maximal oxygen uptake ( [Formula: see text]O2 max) and corresponding high ventilation capacity when using a modern metabolic system with relatively high resistance to breathing (HIGHRES), compared to a traditional system with low resistance to breathing (LOWRES). Four rowers and three cross-country skiers (without asthma), competing at a high international level, performed in experimental conditions with LOWRES and HIGHRES using a rowing ergometer and roller skis on a treadmill. The results showed that [Formula: see text]O2, blood lactate, heart rate and respiratory exchange ratio were not different between the LOWRES and HIGHRES test conditions during both submaximal and maximal exercise. Also, the athlete’s time to exhaustion (treadmill) and mean power (rowing ergometer) from maximal tests were no different between the two conditions. However, ventilation and expiratory O2 and CO2 concentrations were different for both submaximal and maximal exercise. Thus, the authors have concluded that the differences in resistance to breathing of metabolic systems influence elite endurance athletes [Formula: see text] E at low to very high workloads, thus affecting the expired gas fractions, but not the submaximal [Formula: see text]O2, [Formula: see text]O2 max and performance in a laboratory setting at sea level.

Effects of Work and Recovery Duration and Their Ratio on Cardiorespiratory and Metabolic Responses During Aerobic Interval Exercise.

Myrkos, A, Smilios, I, Zafeiridis, A, Iliopoulos, S, Kokkinou, EM, Douda, H, and Tokmakidis, SP. Effects of work and recovery duration and their ratio on cardiorespiratory and metabolic responses during aerobic interval exercise. J Strength Cond Res 36(8): 2169-2175, 2022-This study examined the effect of work and recovery durations and of work-to-rest ratio (WRR) on total exercise time and oxygen consumption (V̇ o2 max), on exercise time above 80, 90, and 95% of V̇ o2 max and HRmax, and on blood lactate concentrations during aerobic interval exercise. Twelve men (22.1 ± 1 year) executed, until exhaustion, 4 interval protocols at an intensity corresponding to 100% of maximal aerobic velocity. Two protocols were performed with work bout duration of 120 seconds and recovery durations of 120 (WRR: 1:1) or 60 seconds (WRR: 2:1), and 2 protocols with work bout duration of 60 seconds and recovery durations of 60 (WRR: 1:1) or 30 seconds (WRR: 2:1). When compared at equal exercise time, total V̇ o2 and exercise time at V̇ o2 above 80, 90, and 95% of V̇ o2 max were longer ( p < 0.05) in 120:120, 120:60 and 60:30 vs. the 60:60 protocol. When analyzed for total exercise time (until exhaustion), total V̇ o2 was higher ( p < 0.01) in the 60:60 compared with all other protocols, and in the 120:120 compared with 120:60. Exercise time >95% of V̇ o2 max and HRmax was higher ( p < 0.05) in the 120:120 vs. the 60:60 protocol; there were no differences among protocols for exercise time >90% of V̇ o2 max and HRmax. Blood lactate was lower ( p < 0.05) in the 60:60 compared with all other protocols and in the 60:30 vs. the 120:60. In conclusion, when interval exercise protocols are executed at similar effort (until exhaustion), work and recovery durations do not, in general, affect exercise time at high oxygen consumption and HR rates. However, as work duration decreases, a higher work-to-recovery ratio (e.g., 2:1) should be used to achieve and maintain high (>95% of maximum) cardiorespiratory stimulus. Longer work bouts and higher work-to-recovery ratio seem to activate anaerobic glycolysis to a greater extent, as suggested by greater blood lactate concentrations.

Ischemic Preconditioning Attenuates Rating of Perceived Exertion But Does Not Improve Maximal Oxygen Consumption or Maximal Power Output.

ter Beek, F, Jokumsen, PS, Sloth, BN, Thomas Stevenson, AJ, and Larsen, RG. Ischemic preconditioning attenuates rating of perceived exertion but does not improve maximal oxygen consumption or maximal power output. J Strength Cond Res 36(9): 2479-2485, 2022-Brief consecutive periods of limb ischemia and reperfusion, known as ischemic preconditioning (IPC), have been reported to increase maximal power output (MPO) during cycling. However, the underlying mechanisms are unclear. Therefore, the purpose of the study was to investigate the effects of IPC on MPO, maximal oxygen consumption (V̇ o2 max), muscle oxygenation, and rating of perceived exertion (RPE) during an incremental cycling test. Fourteen healthy young men participated in this double-blinded, randomized crossover study, involving IPC (250 mm Hg; four 5-minute cycles of ischemia) and sham (20 mm Hg) treatment followed by an incremental cycling test to exhaustion. During the cycling test, V̇ o2 , RPE, heart rate (HR), blood lactate (BL), and muscle oxygenation and deoxygenation (near-infrared spectroscopy) were measured. MPO, V̇ o2 max, HRmax, and muscle deoxygenation did not change with IPC (all p -values > 0.13). Furthermore, IPC had no significant effect on V̇ o2 , HR, or muscle oxygenation during the incremental cycling test (all p -values > 0.18). However, IPC attenuated RPE during cycling at 210 W (IPC: median 17.0 [interquartile range 15.3-19.0]; sham: 17.5 [17.0-19.0]; p = 0.007) and 245 W (IPC: 18.0 [17.0-18.8]; sham: 19.0 [18.0-19.8]; p = 0.011). A single session of IPC did not improve MPO, V̇ o2 max, or measures of oxygen consumption during the cycling test. However, IPC lowered RPE at 210 and 245 W, suggesting that IPC may attenuate the perception of effort at higher submaximal exercise intensities.

Endurance exercise training in pulmonary hypertension increases skeletal muscle electron transport chain supercomplex assembly.

Pulmonary hypertension is associated with pronounced exercise intolerance (decreased V ċ O2 max) that can significantly impact quality of life. The cause of exercise intolerance in pulmonary hypertension remains unclear. Mitochondrial supercomplexes are large respiratory assemblies of individual electron transport chain complexes which can promote more efficient respiration. In this study, we examined pulmonary hypertension and exercise-induced changes in skeletal muscle electron transport chain protein expression and supercomplex assembly. Pulmonary arterial hypertension was induced in rats with the Sugen/Hypoxia model (10% FiO2, three weeks). Pulmonary arterial hypertension and control rats were assigned to an exercise training protocol group or kept sedentary for one month. Cardiac function and V ċ O2 max were assessed at the beginning and end of exercise training. Red (Type 1—oxidative muscle) and white (Type 2—glycolytic muscle) gastrocnemius were assessed for changes in electron transport chain complex protein expression and supercomplex assembly via SDS- and Blue Native-PAGE. Results showed that pulmonary arterial hypertension caused a significant decrease in V ċ O2 max via treadmill testing that was improved with exercise (P < 0.01). Decreases in cardiac output and pulmonary acceleration time due to pulmonary arterial hypertension were not improved with exercise. Pulmonary arterial hypertension reduced expression in individual electron transport chain complex protein expression (NDUFB8 (CI), SDHB (CII), Cox IV (CIV), but not UQCRC2 (CIII), or ATP5a (CV)) in red gastrocnemius muscle. Both red gastrocnemius and white gastrocnemius electron transport chain expression was unaffected by exercise. However, non-denaturing Blue Native-PAGE analysis of mitochondrial supercomplexes demonstrated increases with exercise training in pulmonary arterial hypertension in the red gastrocnemius but not white gastrocnemius muscle. Pulmonary arterial hypertension-induced exercise intolerance is improved with exercise and is associated with muscle type specific alteration in mitochondrial supercomplex assembly and expression of mitochondrial electron transport chain proteins.