The Relationship between VO2 and Muscle Deoxygenation Kinetics and Upper Body Repeated Sprint Performance in Trained Judokas and Healthy Individuals

The present study sought to investigate if faster upper body oxygen uptake (VO2) and hemoglobin/myoglobin deoxygenation ([HHb]) kinetics during heavy intensity exercise were associated with a greater upper body repeated-sprint ability (RSA) performance in a group of judokas and in a group of individuals of heterogenous fitness level. Eight judokas (JT) and seven untrained healthy participants (UT) completed an incremental step test, two heavy intensity square-wave transitions and an upper body RSA test consisting of four 15 s sprints, with 45 s rest, from which the experimental data were obtained. In the JT group, VO2 kinetics, [HHb] kinetics and the parameters determined in the incremental test were not associated with RSA. However, when the two groups were combined, the amplitude of the primary phase VO2 and [HHb] was positively associated with the accumulated work in the four sprints (ΣWork). Additionally, maximal aerobic power (MAP), peak VO2 and the first ventilatory threshold (VT1) showed a positive correlation with ΣWork and an inverse correlation with the decrease in peak power output (Dec-PPO) between the first and fourth sprints. Faster VO2 and [HHb] kinetics do not seem to be associated with an increased upper body RSA in JT. However, other variables of aerobic fitness seem to be associated with an increased upper body RSA performance in a group of individuals with heterogeneous fitness level.

Discontinuous gas exchange in Madagascan hissing cockroaches is not a consequence of hysteresis around a fixed PCO2 threshold

It has been hypothesised that insects display discontinuous gas-exchange cycles (DGCs) due to hysteresis in their ventilatory control, where CO2-sensitive respiratory chemoreceptors respond to changes in hemolymph PCO2 only after some delay. If correct, DGCs would be a manifestation of an unstable feedback loop between chemoreceptors and ventilation causing PCO2 to oscillate around some fixed threshold value: PCO2 above this ventilatory threshold would stimulate excessive hyperventilation, driving PCO2 below the threshold and causing a subsequent apnoea. This hypothesis was tested by implanting micro-optodes into the hemocoel of Madagascar hissing cockroaches and measuring hemolymph PO2 and PCO2 simultaneously during continuous and discontinuous gas exchange. The mean hemolymph PCO2 of 1.9 kPa measured during continuous gas exchange was assumed to represent the threshold level stimulating ventilation, and this was compared with PCO2 levels recorded during DGCs elicited by decapitation. Cockroaches were also exposed to hypoxic (PO2 10 kPa) and hypercapnic (PCO2 2 kPa) gas mixtures to manipulate hemolymph PO2 and PCO2. Decapitated cockroaches maintained DGCs even when their hemolymph PCO2 was forced above or below the putative ∼2 kPa ventilation threshold, demonstrating that the characteristic oscillation between apnoea and gas exchange is not driven by a lag between changing hemolymph PCO2 and a PCO2 chemoreceptor with a fixed ventilatory threshold. However, it was observed that the gas exchange periods within the DGC were altered to enhance O2 uptake and CO2 release during hypoxia and hypercapnia exposure. This indicates that while respiratory chemoreceptors do modulate ventilatory activity in response to hemolymph gas levels, their role in initiating or terminating the gas exchange periods within the DGC remains unclear.

Impact of ageing on female metabolic flexibility: a cross-sectional pilot study in over-60 active women

Background Ageing influences the metabolic flexibility, albeit the physical status could determine this relationship. This cross-sectional study aims to describe and analyse the metabolic flexibility/inflexibility in a group of active older women, together with the impact of ageing and physical status on their oxidation rates and maximal fat oxidation (MFO). Methods Fifteen volunteers (69.00±6.97 years) from 24 women, completed an incremental cycling test until the second ventilatory threshold. Intensity increased 10W each 3min–15sec, starting at 30W. Gas exchange, heart rate, rate of perceived effort, pain scale and muscle power were registered, together with lactate. VO2 and VCO2 were considered for Fat and CHO oxidation (FATox & CHOox; Frayn’s equation) at the intensities 60%, 80% and 100% from the peak of power in the test (P100). Psychophysiological parameters were compared at MFO/FATmax and P100, together with the main correlation analyses, with and without P100 and VO2 as covariates. Results FATox was low at MFO (0.13; 95%CI [0.09-0.17] g·min−1·kg; 5.61 [3.59-7.63] g·min−1·kg FFM), with a shifting down and leftward of a short oxidation-rate curves. CHOox and FATox were both low for a reduced power with age (77.14±18.58 W & 39.29±9.17 W at P100 and MFO respectively), pointing to metabolic inflexibility in older women despite being active. Notwithstanding, the negative correlation between age and MFO (r=-0.54, p=0.04; R2=0.29) disappeared when normalized with P100 (r=-0.17, p=0.53), which was in turn strongly and negatively associated to age (r=-0.85, p<0.005; R2=0.72). P100 was also positive and moderately associated to MFO (r=0.71, p=0.01; R2=0.50). Conclusions Despite the inflexibility with age, physical status (i.e., larger muscular power) suggest a key role in the preservation of the metabolic health with aging in active women.

Cardiorespiratory kinetics in exercise physiology: estimates and predictions using randomized changes in work rate

Purpose Kinetics of cardiorespiratory parameters (CRP) in response to work rate (WR) changes are evaluated by pseudo-random binary sequences (PRBS testing). In this study, two algorithms were applied to convert responses from PRBS testing into appropriate impulse responses to predict steady states values and responses to incremental increases in exercise intensity. Methods 13 individuals (age: 41 ± 9 years, BMI: 23.8 ± 3.7 kg m−2), completing an exercise test protocol, comprising a section of randomized changes of 30 W and 80 W (PRBS), two phases of constant WR at 30 W and 80 W and incremental WR until subjective fatigue, were included in the analysis. Ventilation ($$\dot{V}_{{\text{E}}}$$ V ˙ E ), O2 uptake ($$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 ), CO2 output ($$\dot{V}{\text{CO}}_{2}$$ V ˙ CO 2 ) and heart rate (HR) were monitored. Impulse responses were calculated in the time domain and in the frequency domain from the cross-correlations of WR and the respective CRP. Results The algorithm in the time domain allows better prediction for $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 and $$\dot{V}{\text{CO}}_{2}$$ V ˙ CO 2 , whereas for $$\dot{V}_{{\text{E}}}$$ V ˙ E and HR the results were similar for both algorithms. Best predictions were found for $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 and HR with higher (3–4%) 30 W steady states and lower (1–4%) values for 80 W. Tendencies were found in the residuals between predicted and measured data. Conclusion The CRP kinetics, resulting from PRBS testing, are qualified to assess steady states within the applied WR range. Below the ventilatory threshold, $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 and HR responses to incrementally increasing exercise intensities can be sufficiently predicted.

The importance of aerobic capacity and nutrition in recreational master mountain runners’ performance and race-induced changes in body composition and biochemical blood indices

This study aimed to explore the importance of aerobic capacity and nutrition on 28-km mountain running performance and race-induced changes in body composition and biochemical blood indices, in recreational master athletes of different performance levels. Twenty male master runners (age: 44.6 ± 7.7 years) were divided into two groups, slower and faster runners, according to their race performance. Maximum oxygen uptake [Formula: see text], velocity at [Formula: see text] [Formula: see text], oxygen consumption [Formula: see text], and velocity [Formula: see text] during the second ventilatory threshold were evaluated. Nutrition was assessed for one week before and during the race. Body composition was evaluated, and blood samples were collected before and 3 h after the race. Slower runners exhibited a greater reduction in lean body mass and greater changes in all muscle damage/inflammation/metabolism blood indices than the faster runners ( η2 = 0.201–0.927; p < 0.05). When all the participants were assessed as one group ( n = 20), significant correlations were found between [Formula: see text], vVO2Thr, race time, energy intake, expenditure, carbohydrate, protein intakes, and post-race changes in body composition and blood markers ( r: −0.825–0.824; p < 0.05). The strongest determinants were [Formula: see text] and vVO2Thr, while energy intake, expenditure, carbohydrate, and protein intakes seemed to be the weakest determinants of race performance and race-induced changes in body composition and blood indices. The results suggest that race-induced changes in body composition and blood indices are determined mainly by master runners’ race performance and endurance capacity and to a lesser extent by nutrition. However, it seems that carbohydrate and protein intakes have equal importance.

Influence of COVID-19 Restrictions on Training and Physiological Characteristics in U23 Elite Cyclists

PURPOSE: The COVID-19 pandemic and its associated mobility restrictions caused many athletes to adjust or reduce their usual training load. The aim of this study was to investigate how the COVID-19 restrictions affected training and performance physiology measures in U23 elite cyclists. METHODS: Twelve U23 elite cyclists (n = 12) participated in this study (mean ± SD: Age 21.2 ± 1.2 years; height 182.9 ± 4.7 cm; body mass 71.4 ± 6.5 kg). Training characteristics were assessed between 30 days pre, during, and post COVID-19 restrictions, respectively. The physiological assessment in the laboratory was 30 days pre and post COVID-19 restrictions and included maximum oxygen uptake (V̇O2max), peak power output for sprint (SprintPmax), and ramp incremental graded exercise (GXTPmax), as well as power output at ventilatory threshold (VT) and respiratory compensation point (RCP). RESULTS: Training load characteristics before, during, and after the lockdown remained statistically unchanged (p > 0.05) despite large effects (>0.8) with mean reductions of 4.7 to 25.0% during COVID-19 restrictions. There were no significant differences in maximal and submaximal power outputs, as well as relative and absolute V̇O2max between pre and post COVID-19 restrictions (p > 0.05) with small to moderate effects. DISCUSSION: These results indicate that COVID-19 restrictions did not negatively affect training characteristics and physiological performance measures in U23 elite cyclists for a period of <30 days. In contrast with recent reports on professional cyclists and other elite level athletes, these findings reveal that as long as athletes are able to maintain and/or slightly adapt their training routine, physiological performance variables remain stable.

Novel Computerized Method for Automated Determination of Ventilatory Threshold and Respiratory Compensation Point

Introduction: The ventilatory threshold (named as VT1) and the respiratory compensation point (named as VT2) describe prominent changes of metabolic demand and exercise intensity domains during an incremental exercise test.Methods: A novel computerized method based on the optimization method was developed for automatically determining VT1 and VT2 from expired air during a progressive maximal exercise test. A total of 109 peak cycle tests were performed by members of the US astronaut corps (74 males and 35 females). We compared the automatically determined VT1 and VT2 values against the visual subjective and independent analyses of three trained evaluators. We also characterized VT1 and VT2 and the respective absolute and relative work rates and distinguished differences between sexes.Results: The automated compared to the visual subjective values were analyzed for differences with t test, for agreement with Bland–Altman plots, and for equivalence with a two one-sided test approach. The results showed that the automated and visual subjective methods were statistically equivalent, and the proposed approach reliably determined VT1 and VT2 values. Females had lower absolute O2 uptake, work rate, and ventilation, and relative O2 uptake at VT1 and VT2 compared to men (p ≤ 0.04). VT1 and VT2 occurred at a greater relative percentage of their peak VO2 for females (67 and 88%) compared to males (55 and 74%; main effect for sex: p &lt; 0.001). Overall, VT1 occurred at 58% of peak VO2, and VT2 occurred at 79% of peak VO2 (p &lt; 0.0001).Conclusion: Improvements in determining of VT1 and VT2 by automated analysis are time efficient, valid, and comparable to subjective visual analysis and may provide valuable information in research and clinical practice as well as identifying exercise intensity domains of crewmembers in space.

Recent COVID-19 vaccination has minimal effects on the physiological responses to graded exercise in physically active healthy people

Athletes are advised to receive the COVID-19 vaccination to protect them from SARS CoV-2 infection during major competitions. Despite this, many athletes are reluctant to get the COVID-19 vaccine due to concerns that symptoms of vaccinosis may impair athletic performance. OBJECTIVE: To determine the effects of COVID-19 vaccination on the physiological responses to graded exercise. METHODS: Healthy physically active participants completed a 20-minute bout of graded cycling exercise at intensities corresponding to 50, 60, 70 and 80% of the pre-determined V̇O2max before and ~21 days after receiving the COVID-19 vaccine (2 dose Pfizer mRNA or 1 dose Johnson&Johnson). RESULTS: Vaccination had no effect on a large number of physiological responses to exercise measured in blood (e.g. lactate, epinephrine, cortisol) and by respiratory gas exchange (e.g. oxygen uptake, CO2 production, ventilation, respiratory exchange ratio, predicted V̇O2max, ventilatory threshold) (p>0.05). We did, however, find significant elevations in heart rate (~5 bpm) and norepinephrine (p = 0.006 and 0.04, respectively) in response to vigorous (e.g. 70-80% V̇O2max) intensity exercise after vaccination, particularly in those that received the two shot Pfizer mRNA vaccine regimen. These findings held true when compared to demographically matched controls who completed identical bouts of exercise several weeks apart without receiving a vaccine. CONCLUSION: Recent COVID-19 vaccination has minimal effects on the physiological responses to graded exercise in physically active healthy people. The small elevations in cardiovascular and neuroendocrine responses to exercise after the Pfizer mRNA vaccine regimen could have implications for athletes at the elite level and warrants investigation.

The Physiological Profile of Male Professional Soccer Players: The Effect of Playing Division

The purpose of this study was to present the physiological profile of male soccer players who compete in the professional (Division [D] 1, 2, 3) and semi-professional (D4) Greek soccer leagues, and to compare their physiological profile according to playing division. Using 1,095 players (age: 25.2 ± 4.7 years), twelve anthropometric and physiological characteristics (age, height, body mass, BMI, VO2max, velocity of VO2max velocity at ventilatory threshold, maximum heart rate, maximum lactate, squat jump, 35 m sprint and sprinting fatigue index) were assessed. Factorial analysis of variance revealed a significantly (p < 0.05) enhanced physiological profile amongst the professional, compared to semi-professional players, for 10 of the 12 characteristics assessed between divisions. Regarding aerobic parameters, velocity at maximum oxygen uptake was the variable which discriminated professional, from semi-professional players most. With reference to anaerobic parameters, the 35m sprint was the variable which differentiated players between divisions (i.e. D1/D2 vs. D3/D4). Overall, findings in this study present the physiological profile of soccer players within the specified Greek soccer divisions, with differences identified between professional, and semi-professional divisions. These findings suggest that advanced physiological profiles may contribute to a player’s progression to higher divisions of Greek professional soccer.

Do skeletal muscle composition and gene expression as well as acute exercise-induced serum adaptations in older adults depend on fitness status?

Background Inactive physical behavior among the elderly is one risk factor for cardiovascular disease, immobility and increased all-cause mortality. We aimed to answer the question whether or not circulating and skeletal muscle biomarkers are differentially expressed depending on fitness status in a group of elderly individuals. Methods Twenty-eight elderly individuals (73.36 ± 5.46 years) participated in this exploratory study after participating as part of the multinational SITLESS-clinical trial (implementation of self-management and exercise programs over 16 weeks). A cardiopulmonary exercise test (CPX) and resting skeletal muscle biopsy were performed to determine individual physiological performance capacity. Participants were categorized into a high physical fitness group (HPF) and a low physical fitness group (LPF) depending on peak oxygen uptake (VO2peak). Serum blood samples were taken before (pre) and after (post) CPX and were examined regarding serum BDNF, HSP70, Kynurenine, Irisin and Il-6 concentrations. Skeletal muscle tissue was analyzed by silver staining to determine the myosin heavy chain (MyHC) composition and selected genes by qRT-PCR. Results HPF showed lower body weight and body fat, while skeletal muscle mass and oxygen uptake at the first ventilatory threshold (VO2T1) did not differ between groups. There were positive associations between VO2peak and VO2VT1 in HPF and LPF. MyHC isoform quantification revealed no differences between groups. qRT-PCR showed higher expression of BDNF and BRCA1 in LPF skeletal muscle while there were no differences in other examined genes regarding energy metabolism. Basal serum concentrations of Irisin were higher in HPF compared to LPF with a trend towards higher values in BDNF and HSP70 in HPF. Increases in Il-6 in both groups were observed post. Conclusions Although no association between muscle composition/VO2peak with fitness status in older people was detected, higher basal Irisin serum levels in HPF revealed slightly beneficial molecular serum and muscle adaptations. Trial registration ClinicalTrials.gov, NCT02629666. Registered 19 November 2015.