The effect of ischemic preconditioning on physical fitness and performance: a meta-analysis in healthy adults.

PURPOSE: This meta-analysis aims to assess the impact of ischemic preconditioning (IPC) on physical fitness and performance, with a focus on its specific role in aerobic endurance, anaerobic endurance, explosive power and strength. METHODS: Systematic searches were conducted across multiple databases (CNKI, CBM, Cochrane Library, Web of Science, PubMed, and Embase) up to September 6, 2023. We included studies that employed randomized controlled trial methods and sham ischemic preconditioning as the placebo group, and two reviewers independently screened literature and extracted data, using Review Manager 5.3 for analysis. RESULTS: This meta-analysis comprises 27 articles with 405 individuals, selected according to specified criteria. IPC significantly increased the blood lactate concentration after anaerobic speed endurance exercise (MD = 0.74, P = 0.03), the blood lactate concentration after incremental exercise (MD = 0.49, P = 0.04), the blood lactate concentration after muscular endurance exercise (MD = 0.68, P = 0.02), and the one-repetition maximum (MD = 1.38, P = 0.00001). Furthermore, it also significantly shortened completion time of the exercises primarily powered by glycolysis (MD = - 0.49, P = 0.01) and completion time of the exercises primarily powered by aerobic system (MD = - 7.27, P = 0.05), while marginally prolonging time to exhaustion (MD = 22.68, P = 0.08). However, IPC had no significant effect on maximum oxygen uptake, blood lactate concentration in fixed-load aerobic endurance exercise, peak power, or peak aerobic power, nor on completion time of the exercises primarily powered by phosphagen system. CONCLUSION: IPC could serve as a method to enhance physical performance, particularly for exercises primarily powered by aerobic system and glycolysis. Future research might explore how various cycles, locations, and widths of IPC affect the physical performance of participants with different activity levels.

Effects of running with surgical masks on cardiopulmonary function in healthy male university students.

[Purpose] In Japan, one measure against the novel coronavirus disease-2019 infection involves the public use of surgical masks. Research indicates that exercising while wearing a mask increases the physical burden, particularly affecting young people during high-intensity exercise. This study examined the effects of wearing masks while running in male university students. [Participants and Methods] The participants were 20 healthy male university students (21.6 ± 1.6 years). The participants underwent cardiopulmonary exercise tests with the masks on and off on different days until exhaustion. The following parameters were measured: exercise duration, Borg Scale rating (respiratory or lower extremities), surface temperature around the mouth, time to sweat onset, metabolic reaction, pulmonary ventilation, and cardiovascular reaction parameters. [Results] The results showed that VO2 max remained consistent between the mask-on and mask-off conditions. However, minute ventilation, respiratory rate, and heart rate decreased in the mask-on condition, which correlated with a reduction in exercise duration. Furthermore, running with the mask significantly decreased the VE/VO2, VE/ VO2, Borg Scale rating of the lower extremities, and the time to sweat onset. [Conclusion] Running with a surgical mask affected respiratory function and decreased exercise duration in healthy male university students. However, it did not induce any changes in VO2 max.

Allometry: revealing evolution's engineering principles.

An animal's body size impacts many aspects of its structure and function (Y); insights that only become apparent when viewed over several orders of magnitude of body mass (M) and expressed allometrically in the form of power law equations (Y=aMb). The resulting relationships are apparent clusters of similar exponents (b) revealing emergent 'patterns of design' that shed light on the universal principles of structure and function. Basic physical principles of surface area, volume and heat exchange apply to all objects, including animals, and many consequences must be attributed to these fundamental properties. Starting with Galileo's description of the shapes of bones in the 16th century and extending to 19th century explanations of heat production and loss by Sarrus and Rameaux, allometric patterns have provided numerous biological insights. Here, we examine several of these insights and explore how the selective pressures and scaling may differ when comparing animals in a vegetative (basal) state and those utilizing their maximum metabolic capacities. It seems that the selective pressures under those two conditions differ. We caution that allometric patterns invite explanations that lack supporting data or may be dismissed because there is hesitation among biologists to make comparisons lacking phylogenetic support. We argue that emergent allometric patterns have inherent value and continue to be the fodder for many fruitful hypotheses.

Test-retest reliability of ski-specific aerobic, sprint, and neuromuscular performance tests in highly trained cross-country skiers.

PURPOSE: Laboratory tests are commonly performed by cross-country (XC) skiers due to the challenges of obtaining reliable performance indicators on snow. However, only a few studies have reported reliability data for ski-specific test protocols. Therefore, this study examined the test-retest reliability of ski-specific aerobic, sprint, and neuromuscular performance tests. METHODS: Thirty-nine highly trained XC skiers (26 men and 13 women, age: 22 ± 4 years, V̇O2max : 70.1 ± 4.5 and 58.8 ± 4.4 mL·kg-1 ·min-1 , respectively) performed two test trials within 6 days of a diagonal V̇O2max test, n = 27; skating graded exercise test to assess the second lactate threshold (LT2 ), n = 27; 24-min double poling time trial (24-min DP, n = 25), double poling sprint test (SprintDP1 , n = 27), and 1-min self-paced skating sprint test (Sprint1-min , n = 26) using roller skis on a treadmill, and an upper-body strength test (UB-ST, n = 27) to assess peak power (Ppeak ) with light, medium, and heavy loads. For each test, the coefficient of variation (CV), intraclass correlation coefficient (ICC), and minimal detectable change (MDC) were calculated. RESULTS: V̇O2max demonstrated good-to-excellent reliability (CV = 1.4%; ICC = 0.99; MDC = 112 mL·min-1 ), whereas moderate-to-excellent reliability was found for LT2 (CV = 3.1%; ICC = 0.95). Performance during 24-min DP, SprintDP1 , and Sprint1-min showed good-to-excellent reliability (CV = 1.0%-2.3%; ICC = 0.96-0.99). Absolute reliability for UB-ST Ppeak was poor (CV = 4.9%-7.8%), while relative reliability was excellent (ICC = 0.93-0.97) across the loads. CONCLUSION: In highly trained XC skiers, sport-specific aerobic and sprint performance tests demonstrated high test-retest reliability, while neuromuscular performance for the upper body was less reliable. Using the presented protocols, practitioners can assess within- and between-season changes in relevant performance indicators.

Characterizing the hypoxic performance of a fish using a new metric: PAAS-50.

The hypoxic constraint on peak oxygen uptake (MO2,peak) was characterized in rainbow trout over a range of ambient oxygen tensions with different testing protocols and statistical models. The best-fit model was selected using both statistical criteria (R2 and AIC) and the model's prediction of three anchor points for hypoxic performance: critical PO2 (Pcrit), maximum MO2 and a new metric, the minimum PO2 that supports 50% of absolute aerobic scope (PAAS-50). The best-fitting model was curvilinear using five strategically selected PO2 values. This model predicted PAAS-50 as 70 mmHg (coefficient of variation, CV=9%) for rainbow trout. Thus, while a five-point hypoxic performance curve can characterize the limiting effects of hypoxia in fish, as envisaged by Fry over 75 years ago, PAAS-50 is a promising metric to compare hypoxic constraints on performance in a standardized manner both within and across fish species.

Effect of high-intensity interval training on aerobic capacity and fatigue among patients with prostate cancer: a meta-analysis.

OBJECTIVE: This study focused on evaluating whether high-intensity interval training (HIIT) had an effect on aerobic capacity and fatigue among patients with prostate cancer (PCa) and exploring its effect on the immune system of PCa patients. METHODS: To investigate the potential effect of HIIT on patients with prostate cancer, a meta-analysis was carried out. From January 2012 to August 2022, studies that met predefined criteria were searched in the Scopus, PubMed, Web of Science, and EBSCO databases. Analysis of the standardized mean differences was performed using Review Manager 5.4.1 software with a 95% confidence interval. RESULTS: This review examined a total of 6 articles. There were 215 male patients with PCa involved, and the mean age was 64.4 years. According to the results of the meta-analysis, the HIIT group (n = 63) had greater VO2peak (P<0.01) than the control group (CON) (n = 52) (P = 0.30, I2 = 19% in the heterogeneity test; MD, 1.39 [0.50, 2.27]). Moreover, fatigue was significantly different (P<0.01) between the HIIT (n = 62) and CON (n = 61) groups (P = 0.78, I2 = 0% in the heterogeneity test; SMD, -0.52 [-0.88, -0.16]). Furthermore, among PCa patients, HIIT showed higher efficacy (P < 0.01) in decreasing PSA than the CON regimen (P=0.22, I2 = 34% in the heterogeneity test; MD, -1.13 [-1.91, -0.34]). CONCLUSIONS: HIIT improves aerobic capacity, fatigue, and PSA levels among PCa patients but does not significantly affect IL-6 or TNF-α content. Therefore, HIIT may be a novel and potent intervention scheme for PCa patients.

Dose-response and temporal ergogenic effects of ginseng supplementation in athletes and active participants: A systematic review and meta-analysis.

This review sought to assess the dose-response, i.e., low (<300 mg/day) and high (>300 mg/day), and temporal effects of ginseng, i.e., immediate, short-term (up to 4 weeks) and long-term (>4 weeks) in comparison to placebo on physical performance [visual analogue scale (VAS) level, vertical jump(VJ), rating of perceived exertion (RPE), peak power output (PPO)] and physiological measures [VO2 max, creatine kinase(CK), heart rate(HR)], in athletes and active participants. Search in four databases with English language constraints yielded 492 studies. Fourteen studies were shortlisted through PEDro scale by methodological quality evaluation. Ginseng exhibited significant short-term effect at high dosage for VJ improvement (SMD: -8.17, 95% CI: -16.28 to -0.06, p= 0.05). Ginseng had no effect on VAS (SMD: -0.65, 95% CI: -1.35 to 0.06, p= 0.07), RPE (SMD: -1.11, 95% CI: -2.57 to 0.35, p= 0.14), PPO (SMD: -0.70, 95% CI: -1.78 to 0.38, p= 0.20), HR (SMD: -0.54, 95% CI: -2.05 to 0.96, p= 0.48), CK (SMD: 0.33, 95% CI: -0.18 to 0.84, p= 0.21) and VO2 max (SMD: 0.08, 95% CI: -0.69 to 0.85, p= 0.08).The ginseng supplementation was found to have significant short-term effect at high dose only for VJ in athletic and active participants. Methodologically strong research is warranted to further consolidate these findings.

Changes in submaximal and maximal measures of cardio-respiratory fitness resulting from 6-days of mountain walking.

Trekking is a popular activity associated with cardiovascular benefits. The aim of the present study was to investigate changes in the submaximal heart rate, oxygen uptake, oxygen pulse, and blood lactate concentration associated with a 6-day mountain walk. Over a 12-year period, 134 male (age 21.0 ± 1.4 years) and 124 female undergraduates (age 20.8 ± 1.6 years) participated. Three days before the trek submaximal and maximal laboratory measures were made on participants walking on a motorized treadmill using a breath-by-breath system to measure oxygen uptake (VO2) during exercise. Oxygen uptake and heart rate were recorded during steady-state exercise at treadmill gradients 0, 4, 8, 12, and 16%. Measurements were made, at the same time of day, two days after the trek. There were significant improvements in both the walking economy and the relative exercise intensity (%VO2max) at submaximal treadmill gradients 0-16%. Post-trek, heart rate was lower while oxygen pulse was higher, at each treadmill gradient. There was a significant increase in the maximal oxygen uptake for men (+2.7%) and women (+2.9%). The results of the present study suggest that improvements in cardiorespiratory fitness are associated with a 6-day mountain walk with no sex difference in the exercise response.      .

Effects of Circuit Resistance Training on Body Composition, Strength, and Cardiorespiratory Fitness in Middle-Aged and Older Women: A Systematic Review and Meta-Analysis.

A systematic review with meta-analysis was conducted to evaluate the effects of circuit resistance training (CRT) on cardiorespiratory fitness, strength, and body composition in middle-aged and older women. Sixteen studies were included in the meta-analysis. The CRT interventions led to a significant decrease in weight, body mass index, and fat mass along with an increase in muscle mass. Significant differences were found in the fat mass and a trend to develop muscle mass when compared with the control group. CRT led to a significant increase in VO2max, walking endurance, and time to exhaustion; likewise, significant differences were observed when compared with the control group. CRT had a moderate and large favorable effect on arm, trunk, and lower limb strength. Furthermore, the increases in strength observed in the CRT were significantly greater than the changes observed in the control group. In middle-aged and older women, CRT improved cardiorespiratory fitness and strength and optimized body composition.

Individual characteristics associated with the magnitude of heat acclimation adaptations.

PURPOSE: The magnitude of heat acclimation (HA) adaptations varies largely among individuals, but it remains unclear what factors influence this variability. This study compared individual characteristics related to fitness status and body dimensions of low-, medium-, and high responders to HA. METHODS: Twenty-four participants (9 female, 15 male; maximum oxygen uptake [[Formula: see text]O2peak,kg] 52 ± 9 mL kg-1 min-1) completed 10 daily controlled-hyperthermia HA sessions. Adaptations were evaluated by heat stress tests (HST; 35 min cycling 1.5 W  kg-1; 33 °C, 65% relative humidity) pre- and post-HA. Low-, medium-, and high responder groups were determined based on tertiles (n = 8) of individual adaptations for resting rectal temperature (Tre), exercise-induced Tre rise (ΔTre), whole-body sweat rate (WBSR), and heart rate (HR). RESULTS: Body dimensions (p > 0.3) and [Formula: see text]O2peak,kg (p > 0.052) did not differentiate low-, medium-, and high responders for resting Tre or ΔTre. High WBSR responders had a larger body mass and lower body surface area-to-mass ratio than low responders (83.0 ± 9.3 vs 67.5 ± 7.3 kg; 249 ± 12 vs 274 ± 15 cm2 kg-1, respectively; p < 0.005). Conversely, high HR responders had a smaller body mass than low responders (69.2 ± 6.8 vs 83.4 ± 9.4 kg; p = 0.02). [Formula: see text]O2peak,kg did not differ among levels of responsiveness for WBSR and HR (p > 0.3). CONCLUSION: Individual body dimensions influenced the magnitude of sudomotor and cardiovascular adaptive responses, but did not differentiate Tre adaptations to HA. The influence of [Formula: see text]O2peak,kg on the magnitude of adaptations was limited.

Training status affects between-protocols differences in the assessment of maximal aerobic velocity.

PURPOSE: Continuous incremental protocols (CP) may misestimate the maximum aerobic velocity (Vmax) due to increases in running speed faster than cardiorespiratory/metabolic adjustments. A higher aerobic capacity may mitigate this issue due to faster pulmonary oxygen uptake ([Formula: see text]O2) kinetics. Therefore, this study aimed to compare three different protocols to assess Vmax in athletes with higher or lower training status. METHODS: Sixteen well-trained runners were classified according to higher (HI) or lower (LO) [Formula: see text]O2max [Formula: see text]O2-kinetics was calculated across four 5-min running bouts at 10 km·h-1. Two CPs [1 km·h-1 per min (CP1) and 1 km·h-1 every 2-min (CP2)] were performed to determine Vmax [Formula: see text]O2max, lactate-threshold and submaximal [Formula: see text]O2/velocity relationship. Results were compared to the discontinuous incremental protocol (DP). RESULTS: Vmax, [Formula: see text]O2max, [Formula: see text]CO2 and VE were higher [(P < 0.05,(ES:0.22/2.59)] in HI than in LO. [Formula: see text]O2-kinetics was faster [P < 0.05,(ES:-2.74/ - 1.76)] in HI than in LO. [Formula: see text]O2/velocity slope was lower in HI than in LO [(P < 0.05,(ES:-1.63/ - 0.18)]. Vmax and [Formula: see text]O2/velocity slope were CP1 > CP2 = DP for HI and CP1 > CP2 > DP for LO. A lower [P < 0.05,(ES:0.53/0.75)] Vmax-difference for both CP1 and CP2 vs DP was found in HI than in LO. Vmax-differences in CP1 vs DP showed a large inverse correlation with Vmax, [Formula: see text]O2max and lactate-threshold and a very large correlation with [Formula: see text]O2-kinetics. CONCLUSIONS: Higher aerobic training status witnessed by faster [Formula: see text]O2 kinetics led to lower between-protocol Vmax differences, particularly between CP2 vs DP. Faster kinetics may minimize the mismatch issues between metabolic and mechanical power that may occur in CP. This should be considered for exercise prescription at different percentages of Vmax.

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 ([Formula: see text])-plateau incidence following a heavy-severe prior exercise is caused by a steeper increase in [Formula: see text] and muscle fiber activation in the submaximal intensity domain. METHODS: Twenty-one male participants performed a standard ramp test, a [Formula: see text] 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 [Formula: see text]-([Formula: see text]) and EMG-(∆RMS/∆P) ramp test kinetics. RESULTS: Twenty out of the 21 participants confirmed their [Formula: see text] in the verification bout. The [Formula: see text]-plateau incidence in these participants did not differ between the unprimed (n = 8) and primed (n = 7) ramp test (p = 0.500). The [Formula: see text] 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 [Formula: see text]-plateau incidence as well as steeper increases in [Formula: see text] and muscle fiber activation in the submaximal intensity domain following a heavy-severe prior exercise.

Biological and Social Determinants of Maximum Oxygen Uptake in Adult Men.

The maximum rate of O2 uptake (V̇O2max) is one of the most important positive indicators of health. While the V̇O2max decreases with age, reducing the capacity for physical effort, it can be considerably upregulated through optimal environmental interventions, including systematic physical activity. This study seeks to determine variations in the cardiorespiratory function, estimated from the level of V̇O2max, in 798 employed men aged 20-59, according to biological (age, physical activity, body mass index (BMI), and limb muscle strength and agility) and social (place of residence, education, occupation, economic status, and smoking) predictors. We found that the variables abovementioned, with the exception of smoking and hand strength, were significant predictors of V̇O2max in univariate logistic regression, with age (OR = 0.52; 95%CI 0.47-0.57) and BMI (OR = 0.91; 95%CI 0.90-0.93) having the greatest effect on V̇O2max. The additional predictors, established in multivariate analysis, were the place of residence, education, and hand and arm strength. The multivariate model was fairly well-fitted (Nagelkerke r 2 = 0.54) and had a satisfactory prognostic value, with over 80% of cases classified correctly. Social variance in the V̇O2max makes it desirable to develop and implement the intervention programs with physical activity dedicated for men, especially men who are over the age of 50 years and have an excessive body mass, as this could reduce the risk of disorders and help improve the quality of life and workplace effectiveness of this group.

Validity of a customized submaximal treadmill protocol for determining VO2max.

INTRODUCTION: A customized submaximal exercise test for cycle ergometry was reported as a superior estimate of maximum oxygen uptake (VO2max) in comparison to the traditional YMCA ergometry test. PURPOSE: Following similar methodology, we sought to validate a customized submaximal treadmill test (CustomTM) compared with the widely used Bruce submaximal protocol. METHODS: Participants (29 women and 21 men; age = 31.37 ± 11.44 year, BMI = 24.02 ± 3.03) performed a graded exercise test (GXT) with a subsequent exhaustive, square-wave bout for the verification of "true" VO2max. In counterbalanced order, subjects then completed submaximal protocols. The CustomTM protocol consisted of two 3-min stages estimated at 35 and 70% of VO2max, where VO2max was estimated with a linear regression equation utilizing sex, BMI, age, and self-reported physical activity. RESULTS: VO2 values from the GXT and verification bout were 47.2 ± 7.7 and 47.0 ± 7.7 ml kg-1 min-1, respectively (ICC = 0.99, CV = 2.0%, TE = 0.83 ml kg-1 min-1), with the highest value used as "true" VO2max (47.7 ± 7.7 ml kg-1 min-1). Neither the Bruce (45.95 ± 6.97 ml kg-1 min-1) nor the CustomTM (47.3 ± 9.4 ml kg-1 min-1) protocol differed from "true" VO2max. The CustomTM had a "very large" measurement agreement with "true" VO2max (ICC = 0.78, CV of 9.1%, TE = 4.07 ml kg-1 min-1). Bruce had a "large" measurement agreement with "true" VO2max (ICC = 0.62, CV of 10.0%, TE = 4.51 ml kg-1 min-1). CONCLUSION: The CustomTM was superior to the Bruce protocol, because it included a stage below and above gas exchange threshold, yielded a better measurement agreement for "true" VO2max, and was more time efficient.

Carbohydrate intake and training efficacy - a randomized cross-over study.

Carbohydrate (CHO) availability during endurance exercise seems to attenuate exercise-induced perturbations of cellular homeostasis and might consequently diminish the stimulus for training adaptation. Therefore, a negative effect of CHO intake on endurance training efficacy seems plausible. This study aimed to test the influence of carbohydrate intake on the efficacy of an endurance training program on previously untrained healthy adults. A randomized cross-over trial (8-week wash-out period) was conducted in 23 men and women with two 8-week training periods (with vs. without intake of 50g glucose before each training bout). Training intervention consisted of 4x45 min running/walking sessions/week at 70% of heart rate reserve. Exhaustive, ramp-shaped exercise tests with gas exchange measurements were conducted before and after each training period. Outcome measures were maximum oxygen uptake (VO2max) and ventilatory anaerobic threshold (VT). VO2max and VT increased after training regardless of CHO intake (VO2max: Non-CHO 2.6 ± 3.0 ml*min-1*kg-1 p = 0.004; CHO 1.4 ± 2.5 ml*min-1*kg-1 p = 0.049; VT: Non-CHO 4.2 ± 4.2 ml*min-1*kg-1 p < 0.001; CHO 3.0 ± 4.2 ml*min-1*kg-1 p = 0.003). The 95% confidence interval (CI) for the difference between conditions was between +0.1 and +2.1 ml*min-1*kg-1 for VO2max and between -1.2 and +3.1 for VT. It is concluded that carbohydrate intake could potentially impair the efficacy of an endurance training program.

A 6-minute sub-maximal run test to predict VO2 max.

Maximal oxygen uptake ([Formula: see text] max) is a key indicator to assess health as well as sports performance. Currently, maximal exercise testing is the most accurate measure of maximal aerobic power, since submaximal approaches are still imprecise. In this paper, we propose a new method to predict [Formula: see text] max from a submaximal, low intensity, test in sports men and women. 182 males and 108 females from the High Performance Center of Pontevedra (Spain), aged 10-46 years old, with a [Formula: see text] max between 30.1 and 81.2 mL·min-1·kg-1, completed a maximal incremental test to volitional exhaustion. The test began at a speed of 6 km·h-1 and increased by 0.25 km·h-1 every 15 seconds. Using the data gathered during the first 6 minutes of the test, two different regression models were adjusted using functional data analysis and a traditional linear regression model with scalar covariates. The functional regression model obtained the best results, adjusted r2 = 0.845 and RMSE = 2.8 mL·min-1·kg-1, but the linear regression model also obtained a good fit, adjusted r2 = 0.798 and RMSE = 3.5 mL·min-1·kg-1. Both methods are more accurate than classical submaximal tests, although oxygen consumption needs to be measured during the test.

Exercise-responsive phosphoproteins in the heart.

Endurance exercise improves cardiac performance and affords protection against cardiovascular diseases but the signalling events that mediate these benefits are largely unexplored. Phosphorylation is a widely studied post-translational modification involved in intracellular signalling, and to discover novel phosphorylation events associated with exercise we have profiled the cardiac phosphoproteome response to a standardised exercise test to peak oxygen uptake (VO2peak). Male Wistar rats (346±18g) were assigned to 3 independent groups (n=6, in each) that were familiarised with running on a motorised treadmill within a metabolic chamber. Animals performed a graded exercise test and were killed either immediately (0h) after or 3h after terminating the test at a standardised physiological end point (i.e. peak oxygen uptake; VO2peak). Control rats were killed at a similar time of day to the exercised animals, to minimise possible circadian effects. Cardiac proteins were digested with trypsin and phosphopeptides were enriched by selective binding to titanium dioxide (TiO2). Phosphopeptides were analysed by liquid chromatography and high-resolution tandem mass spectrometry, and phosphopeptides were quantified by MS1 intensities and identified against the UniProt knowledgebase using MaxQuant (data are available via ProteomeXchange, ID PXD006646). The VO2peak of rats in the 0h and 3h groups was 66±5mlkg-1min-1 and 69.8±5mlkg-1min-1, respectively. Proteome profiling detected 1169 phosphopeptides and one-way ANOVA found 141 significant (P<0.05 with a false discovery rate of 10%) differences. Almost all (97%) of the phosphosites that were responsive to exercise are annotated in the PhosphoSitePlus database but, importantly, the majority of these have not previously been associated with the cardiac response to exercise. More than two-thirds of the exercise-responsive phosphosites were different from those identified in previous phosphoproteome profiling of the cardiac response to ß1-adrenergic receptor stimulation. Moreover, we report entirely new phosphorylation sites on 4 cardiac proteins, including S81 of muscle LIM protein, and identified 7 exercise-responsive kinases, including myofibrillar protein kinases such as obscurin, titin and the striated-muscle-specific serine/threonine kinase (SPEG) that may be worthwhile targets for future investigation.

Validity of a Newly-Designed Rectilinear Stepping Ergometer Submaximal Exercise Test to Assess Cardiorespiratory Fitness.

The maximum oxygen uptake (V̇O2 max), determined from graded maximal or submaximal exercise tests, is used to classify the cardiorespiratory fitness level of individuals. The purpose of this study was to examine the validity and reliability of the YMCA submaximal exercise test protocol performed on a newly-designed rectilinear stepping ergometer (RSE) that used up and down reciprocating vertical motion in place of conventional circular motion and giving precise measurement of workload, to determine V̇O2 max in young healthy male adults. Thirty-two young healthy male adults (32 males; age range: 20-35 years; height: 1.75 ± 0.05 m; weight: 67.5 ± 8.6 kg) firstly participated in a maximal-effort graded exercise test using a cycle ergometer (CE) to directly obtain measured V̇O2 max. Subjects then completed the progressive multistage test on the RSE beginning at 50W and including additional stages of 70, 90, 110, 130, and 150W, and the RSE YMCA submaximal test consisting of a workload increase every 3 minutes until the termination criterion was reached. A metabolic equation was derived from the RSE multistage exercise test to predict oxygen consumption (V̇O2) from power output (W) during the submaximal exercise test (V̇O2 (mL·min-1 )=12.4 ×W(watts)+3.5 mL·kg-1·min-1×M+160mL·min-1, R2= 0.91, standard error of the estimate (SEE) = 134.8mL·min-1). A high correlation was observed between the RSE YMCA estimated V̇O2 max and the CE measured V̇O2 max (r=0.87). The mean difference between estimated and measured V̇O2 max was 2.5 mL·kg-1·min-1, with an SEE of 3.55 mL·kg-1·min-1. The data suggest that the RSE YMCA submaximal exercise test is valid for predicting V̇O2 max in young healthy male adults. The findings show that the rectilinear stepping exercise is an effective submaximal exercise for predicting V̇O2 max. The newly-designed RSE may be potentially further developed as an alternative ergometer for assessing cardiorespiratory fitness and the promotion of personalized health interventions for health care professionals.

Everest Physiology Pre-2008.

When Edmund Hillary and Tenzing Norgay reached the summit of Mt. Everest in 1953, it was the culmination of many attempts beginning in 1921. Alexander Kellas had actually predicted as early as 1920 that the mountain could be climbed, but the extreme altitude of 8848 m with the consequent oxygen deprivation had foiled previous attempts. One reason for the success of the 1953 expedition was the work done by the British physiologist Griffith Pugh in 1952 when he studied many of the physiological factors at high altitude including the oxygen requirements. Seven years later, Pugh and Hillary teamed up again for the Silver Hut Expedition in 1960-1961 that elucidated many of the problems of very high altitude. A group of physiologists spent several months at an altitude of 5800 m in a prefabricated hut and studied many aspects of exercise, pulmonary gas exchange, control of ventilation, and blood changes. Maximal exercise was measured as high as 7440 m and raised anew the question of whether Everest could ever be climbed without supplementary oxygen. The answer was shown to be yes in 1978 by Messner and Habeler, and 3 years later the American Medical Research Expedition to Everest clarified the physiological adaptations that allow humans to reach the highest point on earth. Five people reached the summit, the barometric pressure there was measured for the first time, and alveolar gas samples from the summit showed the critical importance of the extreme hyperventilation. However, the maximal oxygen consumption for the summit inspired PO2 of 43 mmHg was shown to be only about 1 l min(-1). In other words, the highest point on earth is very close to the limit of human tolerance to oxygen deprivation. As we celebrate the anniversary of Charles Darwin, it would be nice to have an evolutionary explanation for this, but in fact it is a cosmic coincidence.

Physical activity energy expenditure vs cardiorespiratory fitness level in impaired glucose metabolism.

AIM/HYPOTHESIS: Little is known about the relative roles of physical activity energy expenditure (PAEE) and cardiorespiratory fitness (CRF) as determinants of glucose regulation. The aim of this study was to examine the associations of PAEE and CRF with markers of glucose metabolism, and to test the hypothesis that CRF modifies the association between PAEE and glucose metabolism. METHODS: We analysed cross-sectional data from 755 adults from the Danish ADDITION-PRO study. On the basis of OGTT results, participants without known diabetes were classified as having normal glucose tolerance, isolated impaired fasting glycaemia (i-IFG), isolated impaired glucose tolerance (i-IGT), combined IFG + IGT or screen-detected diabetes mellitus. Markers of insulin sensitivity and beta cell function were determined. PAEE was measured using a combined heart rate and movement sensor. CRF (maximal oxygen uptake) was estimated using a submaximal 8 min step test. The associations were examined by linear regression analysis. Results were adjusted for relevant confounders. RESULTS: PAEE and CRF were reduced in individuals with i-IGT, combined IFG + IGT and screen-detected diabetes mellitus, but were not significantly different in individuals with i-IFG compared with those with normal glucose tolerance. When adjusting CRF for PAEE and vice versa, PAEE and CRF were both associated with lower fasting and 2 h insulin and higher peripheral insulin sensitivity. CRF was additionally associated with lower fasting and 2 h glucose and higher insulin sensitivity and beta cell function. There was no interaction between CRF and PAEE for any markers of glucose metabolism. CONCLUSIONS/INTERPRETATION: Only CRF, not PAEE, appears to be independently associated with plasma glucose levels and beta cell function, suggesting that CRF may be particularly important for glycaemic control.