Mean Oxygen Uptake Research Articles

Lamax: determining the optimal test duration for maximal lactate formation rate during all-out sprint cycle ergometry.

This study aimed to ascertain the optimal test duration to elicit the highest maximal lactate formation rate ( Lamax), whilst exploring the underpinning energetics, and identifying the optimal blood lactate sampling period. Fifteen trained to well-trained males (age 27 ± 6years; peak power: 1134 ± 174W) participated in a randomised cross-over design completing three all-out sprint cycling tests of differing test durations (10, 15, and 30s). Peak and mean power output (W and W.kg-1), oxygen uptake, and blood lactate concentrations were measured. Lamax and energetic contributions (phosphagen, glycolytic, and oxidative) were determined using these parameters. The shortest test duration of 10s elicited a significantly (p = 0.003; p < 0.001) higher Lamax (0.86 ± 0.17mmol.L-1.s-1; 95% CI 0.802-0.974) compared with both 15s (0.68 ± 0.18mmol.L-1.s-1; 95% CI 0.596-0.794) and 30s (0.45 ± 0.07mmol.L-1.s-1; 95% CI 0.410-0.487). Differences in Lamax were associated with large effect sizes (d = 1.07, d = 3.15). We observed 81% of the PCr and 53% of the glycolytic work completed over the 30s sprint duration was attained after 10s. BLamaxpost were achieved at 5 ± 2min (ttest 10s), 6 ± 2min (ttest 15s), and 7 ± 2min (ttest 30s), respectively. Our findings demonstrated a 10s test duration elicited the highest Lamax. Furthermore, the 10s test duration mitigated the influence of the oxidative metabolism during all-out cycling. The optimal sample time to determine peak blood lactate concentration following 10s was 5 ± 2min.

Energy System Contributions in Repeated Sprint Tests: Protocol and Sex Comparison.

The aim of this study was to investigate the energy system contributions to different repeated sprint protocols and also to determine sex-related differences in these contributions. Sixteen men and fourteen women team sport athletes randomly performed two cycling repeated sprint protocols with the same total duration (10 x 6 s and 6 x 10 s). Relative peak power (RPP), relative mean power (RMP), performance decrement (PD), oxygen uptake (VO2), blood lactate (LA), heart rate (HR) and ratings of perceived exertion (RPEs) were measured. The contributions of energy systems were calculated from oxygen consumption and lactate values during rest, exercise and recovery phases based on mathematical methods. Findings indicate that men had higher RPP and RMP. RPP did not differ according to protocols, while RMP was higher in the 10 x 6 s protocol. The sex effect in PD was similar; however, it was higher in the 6 x 10 s protocol. The effects of protocols on the maximum HR and LA were similar; however, the 6 x 10 s protocol resulted in higher RPEs. In both protocols women had higher ATP-PCr and men had higher glycolytic system contribution with similar oxidative system contribution. In addition, the 10 x 6 s protocol had higher ATP-PCr system contribution and the 6 x 10 s protocol had higher glycolytic system and oxidative system contributions. In conclusion, the contribution of energy systems, physiological and performance variables showed variations according to sex and different protocols.

Physical Conditioning and Functional Injury-Screening Profile of Elite Female Soccer Players: A Systematic Review.

To identify the physical conditioning and functional injury-screening characteristics of elite female soccer players. This review was prospectively registered (PROSPERO CRD4202346765). Searches were conducted in PubMed/MEDLINE, Cochrane Library, Scopus, and Web of Science (from inception in March 2023 to July 2023). Updated searches were conducted in October 2023 and April 2024. Included studies were quantitative studies conducted on female soccer players. Main outcomes were functional and physical profiles. Screening, data extraction, and quality assessment (Quality Assessment Tool for Quantitative Studies and the Oxford Levels of Evidence scales) were performed. Mean differences between preseason and in-season testing periods were estimated by Hedges g effect size. Methods and results were reported according to PRISMA guidelines. The search yielded 1727 articles, of which 10 were included. Overall methodological quality of the studies was strong, with amoderate level of evidence. Players exhibited mean maximal oxygen uptake of 52.6 (4.5)mL·min-1·kg-1, 20-m linear-sprint performance of 3.58 (0.18)seconds, countermovement jump of 31.0 (2.9)cm, unilateral countermovement jump of 14.4 (2.1)cm, and quadriceps and hamstring peak torque at 60°·s-1 of 133 (23) and 87 (17)N·m, respectively. Mean scores recorded during in-season were 2% to 22% better than in preseason (effect size: small to very large). This review provides valuable normative physical conditioning and functional injury-risk assessment data for elite female soccer players. Coaches and conditioning staff can use these insights to interpret their own records and optimize their training processes. Furthermore, this study identifies methodological limitations to address in future research.

Decadal variability of oxygen uptake, export, and storage in the Labrador Sea from observations and CMIP6 models

The uptake of dissolved oxygen from the atmosphere via air-sea gas exchange and its physical transport away from the region of uptake are crucial for supplying oxygen to the deep ocean. This process takes place in a few key regions that feature intense oxygen uptake, deep water formation, and physical oxygen export. In this study we analyze one such region, the Labrador Sea, utilizing the World Ocean Database (WOD) to construct a 65–year oxygen content time series in the Labrador Sea Water (LSW) layer (0–2200 m). The data reveal decadal variability associated with the strength of deep convection, with a maximum anomaly of 27 mol m–2 in 1992. There is no long-term trend in the time series, suggesting that the mean oxygen uptake is balanced by oxygen export out of the region. We compared the time series with output from nine models of the Ocean Model Intercomparison Project phase 1 in the Climate Model Intercomparison Project phase 6, (CMIP6-OMIP1), and constructed a “model score” to evaluate how well they match oxygen observations. Most CMIP6-OMIP1 models score around 50/100 points and the highest score is 57/100 for the ensemble mean, suggesting that improvements are needed. All of the models underestimate the maximum oxygen content anomaly in the 1990s. One possible cause for this is the representation of air-sea gas exchange for oxygen, with all models underestimating the mean uptake by a factor of two or more. Unrealistically deep convection and biased mean oxygen profiles may also contribute to the mismatch. Refining the representation of these processes in climate models could be vital for enhanced predictions of deoxygenation. In the CMIP6-OMIP1 multi-model mean, oxygen uptake has its maximum in 1980–1992, followed by a decrease in 1994–2006. There is a concurrent decrease in export, but oxygen storage also changes between the two periods, with oxygen accumulated in the first period and drained out in the second. Consequently, the change in oxygen export (5%) is much less than that in uptake (28%), suggesting that newly ventilated LSW which remains in the formation region acts to buffer the linkage between air-sea gas exchange and oxygen export.

Increased oxygen uptake in well-trained runners during uphill high intensity running intervals: A randomized crossover testing.

The time spent above 90% of maximal oxygen uptake ( O2max) during high-intensity interval training (HIIT) sessions is intended to be maximized to improve O2max. Since uphill running serves as a promising means to increase metabolic cost, we compared even and moderately inclined running in terms of time ≥90% O2max and its corresponding physiological surrogates. Seventeen well-trained runners (8 females & 9 males; 25.8 ± 6.8yrs; 1.75 ± 0.08m; 63.2 ± 8.4kg; O2max: 63.3 ± 4.2ml/min/kg) randomly completed both a horizontal (1% incline) and uphill (8% incline) HIIT protocol (4-times 5min, with 90s rest). Mean oxygen uptake ( O2mean), peak oxygen uptake ( O2peak), lactate, heart rate (HR), and perceived exertion (RPE) were measured. Uphill HIIT revealed higher (p ≤ 0.012; partial eta-squared (pes) ≥ 0.351) O2mean (uphill: 3.3 ± 0.6 vs. horizontal: 3.2 ± 0.5L/min; standardized mean difference (SMD) = 0.15), O2peak (uphill: 4.0 ± 0.7 vs. horizontal: 3.8 ± 0.7L/min; SMD = 0.19), and accumulated time ≥90% O2max (uphill: 9.1 ± 4.6 vs. horizontal: 6.4 ± 4.0 min; SMD = 0.62) compared to even HIIT. Lactate, HR, and RPE responses did not show mode*time rANOVA interaction effects (p ≥ 0.097; pes ≤0.14). Compared to horizontal HIIT, moderate uphill HIIT revealed higher fractions of O2max at comparable perceived efforts, heartrate and lactate response. Therefore, moderate uphill HiiT notably increased time spent above 90% O2max.

Accuracy of the 20-m shuttle run test for individualizing exercise intensity of high-intensity interval training

The aim of the study was to investigate the accuracy of the 20 m shuttle run test (20mSRT) for the prescription of high-intensity interval training (HIIT) and to examine the appropriate intensity, prescribed by the 20mSRT end-test speed, for the execution of HIIT. Twenty physical education students (age: 22.4 ± 0.8 years, body height: 175.7 ± 8.9 cm, body weight: 73.8 ± 13.4 kg) participated in the study. On two separate occasions the participants were first tested with a maximal incremental exercise test and the 20mSRT. On another two occasions they were required to perform a 10-minute HIIT session comprised of 15-s runs interspersed with 15-s passive recovery. The intensities of the HIIT sessions were either 100% (T100%) or 110% (T110%) of the end-test speed reached in the 20mSRT. Mean oxygen uptake (VO2) (84.4 ± 5.5% vs 77.8 ± 6.9% of VO2max), mean heart rate (HR) (93 ± 2.8% vs 87.6 ± 4.6% of HRmax), blood lactate concentration (12.6 ± 2.1 vs 5.4 ± 2.6 mmol/l), and ratings of perceived exertion (9.5 ± 0.5 vs 6.7 ± 1) were all significantly (p&amp;lt;.01) higher during T110% vs T100%. The percentage of the total exercise time spent ≥ 90% VO2max (37.6 ± 25.3 vs 18.6 ± 18.0%, p&amp;lt;.05) and ≥ 90% HRmax (73.9 ± 17.7% vs 37.5 ± 33.3, p&amp;lt;.001) were also significantly higher during T110%. The mean VO2 and HR coefficient of variation during T110% were 6.5 and 3%, respectively. The cardiorespiratory, metabolic, and perceptual responses to T110% were reflective of the responses typical for HIIT, while T100% induced insufficient physiological stress to enable optimal cardiorespiratory adaptation. Therefore, the intensity of 110% 20mSRT is preferable for inducing the appropriate acute physiological responses and the 20mSRT can be used to accurately prescribe HIIT.

Repeated cardiopulmonary performance measurements in young competitive handball players with and without SARS-CoV-2 infection

BackgroundThe SARS-CoV-2 virus and its long-term consequences in adolescents have a global impact on upcoming medical issues. The aim of this study was to investigate the effects of a SARS-CoV-2 infection on cardiorespiratory parameters in young athletes.MethodsIn a cohort study involving repeated measurements during a six-month period, cardiorespiratory parameters were assessed in infected (SCoV) and non-infected (noSCoV) athletes. We evaluated handball players (17.2 ± 1.0 years) via performance diagnostics and a specific examination after a SARS-CoV-2 infection or without.ResultsWe observed no significant differences between the two groups at the first visit. But between the first and second visit, the SCoV group’s maximum power output was significantly lower than the noSCoV group’s (− 48.3 ± 12.5; p ≤ 0.01 vs. − 15.0 ± 26.0 W; p = 0.09). At the second visit, lung diffusion capacity (DLCO/VA, %predicted) did not differ between groups (111.6 ± 11.5 vs. 116.1 ± 11.8%; p = 0.45). HR during comparative stress showed no group differences. The SCoV group’s mean oxygen uptake during incremental exercise was lower (Two-way-ANOVA: 1912 vs. 2106 ml; p ≤ 0.01; mean difference: − 194 ml; 95% CI − 317 to − 71); we also noted a significantly lower stroke volume course during exercise (Two-way-ANAOVA: 147.5 vs. 169.5 ml; mean difference: − 22 ml; p ≤ 0.01; 95% CI − 34.2 to − 9.9). The probability of premature ventricular complexes after a SARS-CoV-2 infection yielded an odds ratio of 1.6 (95% CI 0.24–10.81).ConclusionsThe physical performance of young athletes infected with SARS-CoV-2 was impaired. This decreased performance is probably due to cardiac and/or peripheral deconditioning. Studies with larger cohorts are needed to make more profound conclusions.

Physiological Profiling and Energy System Contributions During Simulated Epée Matches in Elite Fencers.

The aim of this study was to investigate physiological responses and energetic contributions during simulated epée matches in elite fencers. Ten elite male fencers participated in simulated epée (direct elimination) matches. Simulated epée matches included 3 bouts of 3minutes each with 1-minute rests between bouts. During these sessions, physiological variables such as mean and peak heart rate, peak and mean oxygen uptake (VO2peak and VO2mean), metabolic equivalents of task in VO2peak and VO2mean, and blood lactate concentrations (peak lactate concentration and delta blood lactate concentration) were measured. Furthermore, energetic contributions (oxidative [WOxi], glycolytic, and phosphagen) and time-motion variables were estimated. Values of peak heart rate, mean heart rate, and WOxi (in percentages) were significantly higher in the second and third bouts compared with the first. VO2peak and metabolic equivalents of task in VO2peak were significantly higher in the first bout compared with the third bout. Values of delta blood lactate concentration and glycolytic contribution (in kilojoules and percentages) were significantly lower in the second and third bouts compared with the first. VO2mean and metabolic equivalents of task in VO2mean were significantly higher in the second bout compared with the third bout. Furthermore, WOxi (in kilojoules and percentage) was significantly higher in all bouts compared with phosphagen and glycolytic contributions. Low positive and negative correlations were seen between WOxi, VO2mean, sum of attacks and defense times, and the sum of time without attacks and defenses. Direct-elimination epée matches consist of high-intensity intermittent exercise, and the oxidative contribution is 80% to 90%. Improving aerobic conditioning may support high-intensity intermittent actions during entire epée matches in elite fencers.

The Modern Double-Poling Technique Is Not More Energy Efficient Than the Old-Fashioned Double-Poling Technique at a Submaximal Work Intensity.

The purpose of the study was to investigate whether there are energy-efficiency differences between the execution of the old-fashioned double-poling technique (DPOLD) and the modern double-poling technique (DPMOD) at a submaximal work intensity among elite male cross-country skiers. Fifteen elite male cross-country skiers completed two 4-min tests at a constant mechanical work rate (MWR) using the DPMOD and DPOLD. During the last minute of each test, the mean oxygen uptake (VO2) and respiratory exchange ratio (RER) were analyzed, from which the metabolic rate (MR) and gross efficiency (GE) were calculated. In addition, the difference between pretest and posttest blood-lactate concentrations (BLadiff) was determined. For each technique, skiers' joint angles (i.e., heel, ankle, knee, hip, shoulder, and elbow) were analyzed at the highest and lowest positions during the double-poling cycle. Paired-samples t-tests were used to investigate differences between DPMOD and DPOLD outcomes. There were no significant differences in either VO2mean, MR, GE, or BLadiff (all P > 0.05) between the DPMOD and DPOLD tests. DPMOD execution was associated with a higher RER (P < 0.05). Significant technique-specific differences were found in either the highest and/or the lowest position for all six analyzed joint angles (all P < 0.001). Hence, despite decades of double-poling technique development, which is reflected in the significant biomechanical differences between DPOLD and DPMOD execution, at submaximal work intensity, the modern technique is not more energy efficient than the old-fashioned technique.

Cardiorespiratory Responses During High-Intensity Interval Training Prescribed by Rating of Perceived Exertion in Patients After Myocardial Infarction Enrolled in Early Outpatient Cardiac Rehabilitation.

Objective: We aimed to determine the cardiorespiratory responses during, and adaptations to, high-intensity interval training (HIIT) prescribed using ratings of perceived exertion (RPE) in patients after myocardial infarction (MI) during early outpatient cardiac rehabilitation (CR).Methods: We prospectively recruited 29 MI patients after percutaneous coronary intervention who began CR within 2 weeks after hospital discharge. Eleven patients (seven men; four women; age: 61 ± 11 yrs) who completed ≥24 supervised HIIT sessions with metabolic gas exchange measured during HIIT once weekly for 8 weeks and performed pre- and post- CR cardiopulmonary exercise tests were included in the study. Each HIIT session consisted of 5–8 high-intensity intervals [HIIs, 1-min RPE 14–17 (Borg 6–20 scale)] and low-intensity intervals (LIIs, 4-min RPE < 12). Metabolic gas exchange, heart rate (HR), and blood pressure during HIIT were measured.Results: The mean oxygen uptake (2) during HIIs across 88 sessions of HIITs [91 (14)% of 2peak, median (interquartile range, IQR)] was significantly higher than the lower limit of target 2 zone (75% of 2peak) recommended for the HII (p < 0.001). Exercise intensity during RPE-prescribed HIITs, determined as %2peak, was highly repeatable with intra-class correlations of 0.95 (95% CI 0.86– 0.99, p < 0.001). For cardiorespiratory adaptations from the first to the last session of HIIT, treadmill speed, treadmill grade, treadmill power, 2HII, %2peak, and VE during HIIs were increased (all p < 0.05), while no difference was found for HR, %HRpeak and systolic blood pressure (all p > 0.05). 2peak increased by an average of 9% from pre-CR to post-CR. No adverse events occurred.Conclusion: Our results demonstrate that HIIT can be effectively prescribed using RPE in MI patients during early outpatient CR. Participation in RPE-prescribed HIIT increases exercise workload and 2 during exercise training without increased perception of effort or excessive increases in heart rate or blood pressure.

Acute Cardiometabolic and Perceptual Responses to Individual and Group-Based Body-Weight Resistance Exercise in Girls.

To compare acute responses to treadmill-based HIIE (TM) and body-weight resistance exercise circuit (CIRC) and to CIRC performed in a small-group setting (group CIRC). Nineteen girls (9.1 [1.1]y) completed exercise testing on a TM to determine peak oxygen uptake, peak heart rate (HRpeak), and maximal aerobic speed. The TM involved eight 30-second sprints at 100% maximal aerobic speed. The CIRC consisted of 8 exercises of maximal repetitions performed for 30 seconds. Each exercise bout was followed by 30 seconds of active recovery. The blood lactate concentration was assessed preexercise and postexercise. The ratings of perceived exertion, affective valence, and enjoyment were recorded at preexercise, Intervals 3 and 6, and postexercise. The mean heart rate was higher during group CIRC (92% [7%] HRpeak) than CIRC (86% [7%] HRpeak) and TM (85% [4%] HRpeak) (ηp2 = .49). The mean oxygen uptake equaled 76% (11%) of the peak oxygen uptake for CIRC and did not differ from TM (d = 0.02). The CIRC elicited a greater postexercise blood lactate concentration versus TM (5.8 [1.7] vs 1.4 [0.4]mM, d = 3.61). The perceptual responses were similar among conditions (P > .05), and only the rating of perceived exertion increased during exercise (ηp2 = .78). Whether performed individually or in a small group, CIRC represents HIIE and may be a feasible alternative to running-based HIIE.

The Effects Of The Nike Vapor Fly 4% Shoes On Running Economy In Fatigued Female Runners

The Nike Vaporfly 4% shoe (VP) has been shown to improve running economy (RE) up to 4% in subelite male runners. Whether these improvements extend to other subject groups, such as female runners or fatigued runners, remains unknown. PURPOSE: The purpose of this study was to determine if trained female runners gain the same 4% improvement in RE as males and if the improvement is observed post-fatigue. METHODS: Nine well-trained collegiate female runners completed one session alternating between the VP and the control shoe, Nike Streaks (NS). Subjects performed three vertical jumps in each shoe on a force pad to determine jump height and estimate stored energy return from each shoe. Subjects then performed two, 5-min treadmill running trials at 6.7 mph using a metabolic cart to measure oxygen consumption. Mean oxygen uptake over the last two minutes of each trial was used to determine RE. Following the first jump and RE trials, subjects performed a 30-minute treadmill run at a self-selected speed to induce fatigue. Subjects then repeated the jump and RE trials in the alternative shoe order. RESULTS: Oxygen consumption in the VP was lower when compared to the NS by 3.7% (31.8 ± 3 vs 33.6 ± 3 ml/kg/min p < 0.05) pre-fatigue and by 2.5% (32.5 ± 3 vs 33.3 ± 3 ml/kg/min p < 0.05) in the fatigued state, which is less than the anticipated 4% benefit. The pre- and post-fatigue reductions in oxygen consumption while wearing the VP were significantly different indicating the benefit of wearing the VP attenuated over time. Jump height in the VP was higher pre-fatigue (44.0 ± 6 vs 43.2 ± 6 cm, p < 0.05) but was not different in the fatigued state (43.8 ± 7 vs 43.6 ± 7 cm, p > 0.05) when compared to NS. CONCLUSION: Female runners experienced a similar improvement in RE while wearing the VP when compared to previous studies, however this improvement dropped to 2.7% following a relatively short fatiguing run. Thus, improvements in RE from the VP shoes may not extend through the entire duration of some running events in certain athletes.

Physiological responses and cycle characteristics during double-poling versus diagonal-stride roller-skiing in junior cross-country skiers

PurposeThis study aimed to compare physiological factors and cycle characteristics during cross-country (XC) roller-skiing at matched inclines and speeds using the double-poling (DP) and diagonal-stride (DS) sub-techniques in junior female and male XC skiers.MethodsTwenty-three well-trained junior XC skiers (11 women, 12 men; age 18.2 ± 1.2 yr.) completed two treadmill roller-skiing tests in a randomized order using either DP or DS. The exercise protocols were identical and included a 5 min warm-up, 4 × 5 min submaximal stages, and an incremental test to exhaustion, all performed at a 5° incline.ResultsNo significant three-way interactions were observed between sex, submaximal exercise intensity, and sub-technique. For the pooled sample, higher values were observed for DP versus DS during submaximal exercise for the mean oxygen uptake kinetics response time (33%), energy cost (18%), heart rate (HR) (9%), blood lactate concentration (5.1 versus 2.1 mmol·L−1), rating of perceived exertion (12%), and cycle rate (25%), while cycle length was lower (19%) (all P < 0.001). During the time-to-exhaustion (TTE) test, peak oxygen uptake (dot{V}O2peak), peak HR, and peak oxygen pulse were 8%, 2%, and 6% lower, respectively, for DP than DS, with a 29% shorter TTE during DP (pooled data, all P < 0.001).ConclusionIn well-trained junior XC skiers, DP was found to exert a greater physiological load than DS during uphill XC roller-skiing at submaximal intensities. During the TTE test, both female and male athletes were able to ski for longer and reached markedly higher dot{V}O2peak values when using DS compared to DP.

Ontogenetic Shifts in Oxygen Uptake in Common Mudskipper (Periophthalmus kalolo) and its Role in Microhabitat Selection

Aims: The common mudskipper, Periophthalmus kalolo is a tropical, amphibious fish that utilizes both air and water as a respiratory medium. Adult oxygen uptake in water and air is well studied, but requirements of post-metamorphosed fish are virtually unknown. Our study quantifies how ontogenetic shifts across mudskipper life stage affects microhabitat choice.&#x0D; Study Design: metabolic rates in air and water were estimated for common mudskippers with mass values from 0.03 to 28.9 grams. Fish in each media were divided into 5 standard length classes (≤ 2.00, 2.01-4.00, 4.01-6.00, 6.01-8.00, ≥ 8.01 cm). Oxygen consumption for each class was calculated as the mean individual oxygen consumption for the group.&#x0D; Place and Duration of Study: Hoga Research Laboratory, Wakatobi National Park, Sulawesi, Indonesia, between June 14 and August 26, 2005.&#x0D; Methodology: Gilson manometry, and flow-through respirometery was used to determine respective aerial and aquatic oxygen uptake values for common mudskippers.&#x0D; Results: Mudskipper lengths varied by an order of magnitude (1.0 to 10.3 cm) and mass varied by three orders of magnitude (0.03 to 17.3 g). Mass-adjusted aerial metabolic rates of fish 2.00 cm or less in length, consumed up to ten times more oxygen than larger fish. whereas, aerial consumption values for size classes 2.01 cm and above did not differ significantly from each other (ANOVA: F4,112 = 40.29, P &lt; 0.0001; SNK, α = 0.05).&#x0D; Metabolic rates of submerged fish fell into two statistically distinct subsets. mudskippers with lengths of 4.00 cm or less had significantly higher metabolic rates than fish in remaining size classes; however, mean oxygen uptake values of fish within subsets did not differ significantly (ANOVA: F4,87 = 6.89, P &lt; 0.0001; SNK, α = 0.05). When oxygen consumption values at each size class were compared, only the smallest mudskipper size class (£ 2.00 cm) differed significantly between air and water (t-test: df = 34, t = 3.44, P &lt; 0.0001). Mudskippers 2 cm in standard length or smaller consumed over seven times more oxygen in air than water. All other size classes had similar rates of oxygen uptake in air and water and air:water oxygen uptake ratios fell to approximately 1:1.&#x0D; Conclusions: (1) Common mudskippers select different mangal habitats based on developmental life stage. (2) Small, post-metamorphosed fish &lt;2 mm in standard length, prefer cool shaded mangal areas, whereas, larger mudskippers utilize sun-exposed zones.&#x0D; (3) Post-metamorphosed fish, consume 10X more oxygen than all other size groups, confirming that juveniles are well suited to aerial respiration oxygen shortly after hatching. (4) Emerged post-metamorphosed fish exploit cooler, wetter pool habitats, thereby ameliorating problems of desiccation, excretion, and/or predation. (5) Ontogenetic shifts are a key life-history event in P. kalolo that promotes wider mangrove habitat use, and plays an important role in establishing common mudskipper as a key mangal species.

Short-term exposure to elevated suspended sediment increases oxygen uptake of gilled larval Eastern Hellbender (Cryptobranchus alleganiensis) salamanders

Freshwater ecosystems are increasingly impacted by anthropogenic elevated levels of suspended sediment that may negatively affect aquatic organisms, including salamanders. Although increasing fine sediment in streams has been suggested as a reason for population declines, to date no study has empirically assessed the effect of suspended sediment on gilled larval Eastern Hellbenders (Cryptobranchus alleganiensis (Sonnini de Manoncourt and Latreille, 1801)), a critical life-history stage and a species of conservation concern. We used custom respirometers to elucidate effects of suspended sediments on larval Eastern Hellbender oxygen uptake in trials conducted in situ in Georgia (USA) streams. Mean oxygen uptake increased and was significantly higher in trials when larval salamanders were exposed to suspended sediment (mean = 5.06 mg O2/L for 800 mg/L of sediment treatment vs. 2.25 mg O2/L for 0.00 mg/L of sediment control). This may indicate elevated physiological stress in response to short-term exposure to suspended sediments. Qualitatively, individuals in both groups exhibited rocking behavior in response to low oxygen (hypoxia), albeit at different frequencies (sediment exposure = 7.6 rocks/min and control = 2.1 rocks/min). Larval salamanders may be able to temporarily compensate for low oxygen through increased rocking behavior when high suspended sediment loads are present, with future respirometry research needed.

Acute Effects of Using Added Respiratory Dead Space Volume in a Cycling Sprint Interval Exercise Protocol: A Cross-Over Study.

Background: The aim of the study was to compare acute physiological, biochemical, and perceptual responses during sprint interval exercise (SIE) with breathing through a device increasing added respiratory dead space volume (ARDSV) and without the device. Methods: The study involved 11 healthy, physically active men (mean maximal oxygen uptake: 52.6 ± 8.2 mL∙kg1∙min−1). During four visits to a laboratory with a minimum interval of 72 h, they participated in (1) an incremental test on a cycle ergometer; (2) a familiarization session; (3) and (4) cross-over SIE sessions. SIE consisted of 6 × 10-s all-out bouts with 4-min active recovery. During one of the sessions the participants breathed through a 1200-mL ARDSv (SIEARDS). Results: The work performed was significantly higher by 4.4% during SIEARDS, with no differences in the fatigue index. The mean respiratory ventilation was significantly higher by 13.2%, and the mean oxygen uptake was higher by 31.3% during SIEARDS. Respiratory muscle strength did not change after the two SIE sessions. In SIEARDS, the mean pH turned out significantly lower (7.26 vs. 7.29), and the mean HCO3– concentration was higher by 7.6%. Average La− and rating of perceived exertion (RPE) did not differ between the sessions. Conclusions: Using ARDSV during SIE provokes respiratory acidosis, causes stronger acute physiological responses, and does not increase RPE.

Mismatch between self-estimated and objectively assessed exercise capacity in patients with congenital heart disease varies in regard to complexity of cardiac defects.

Regular evaluation of physical capacity takes a crucial part in long-term follow-up in patients with congenital heart disease (CHD). This study aims to examine the accuracy of self-estimated exercise capacity compared to objective assessments by cardiopulmonary exercise testing in patients with CHD of various complexity. We conducted a single centre, cross-sectional study with retrospective analysis on 382 patients aged 8-68 years with various CHD who completed cardiopulmonary exercise tests. Peak oxygen uptake was measured. Additionally, questionnaires covering self-estimation of exercise capacity were completed. Peak oxygen uptake was compared to patient's self-estimated exercise capacity with focus on differences between complex and non-complex defects. Peak oxygen uptake was 25.5 ± 7.9 ml/minute/kg, corresponding to 75.1 ± 18.8% of age- and sex-specific reference values. Higher values of peak oxygen uptake were seen in patients with higher subjective rating of exercise capacity. However, oxygen uptake in patients rating their exercise capacity as good (mean oxygen uptake 78.5 ± 1.6%) or very good (mean oxygen uptake 84.8 ± 4.8%) was on average still reduced compared to normal. In patients with non-complex cardiac defects, we saw a significant correlation between peak oxygen uptake and self-estimated exercise capacity (spearman-rho -0.30, p < 0.001), whereas in patients with complex cardiac defects, no correlation was found (spearman-rho -0.11, p < 0.255). The mismatch between self-estimated and objectively assessed exercise capacity is most prominent in patients with complex CHD.Registration number at Charité Universitätsmedizin Berlin Ethics Committee: EA2/106/14.

Metabolic and Cardiovascular Effects of Body Weight Support Treadmill Walking in Healthy Adults

Purpose: Limited and conflicting evidence exists regarding the metabolic and cardiovascular responses of body weight support (BWS) treadmill training (BWSTT). The purpose of this study was to describe the metabolic (as assessed by oxygen uptake) and cardiovascular responses to varying levels of BWSTT in healthy adult subjects. Methods: Twenty-one subjects (10 females; 34.5 [6.7] yr.; 74.6 [14.3] kg; 170.8 [6.9] cm; 26.1 [5.3] kg/m2) provided their informed consent to participate in 3 5-minute walking trials at a self-selected treadmill speed, with BWS of 0%, 15%, and 30%. Test order was randomized. Subjects rested at least 5 minutes between trials and did not begin another trial until the heart rate (HR) was &lt;5 bpm of HR rest. Mean HR, blood pressure (BP), oxygen uptake, and rating of perceived exertion (RPE) were determined from the last 3 minutes of each trial. Mean values for all variables were assessed for difference between trials using repeated-measures analysis of variance. Results: At rest, HR was 78.2 (11.5) bpm and BP was 121.2 (7.9)/76.9 (8.0) mm Hg. Mean walking speed of subjects was 65.4 m/min. Heart rate and systolic BP significantly (P &lt; .05) increased from rest with exercise at each level of BWS, with no significant difference in diastolic BP seen from rest to exercise at all BWS levels. There was no statistical difference among levels of BWS for HR, BP, RPE, oxygen uptake, respiratory exchange ratio, respiratory rate, tidal volume, and metabolic equivalent of tasks. Conclusions: Healthy adult subjects walking at self-selected speeds at BWS levels up to 30% fail to demonstrate significant changes in metabolic and cardiovascular responses.

Maytenus ilicifolia Extract Increases Oxygen Uptake without Changes in Neuromuscular Fatigue Development during a High-Intensity Interval Exercise

Objective We investigated the effects of acute ingestion of Maytenus ilicifolia extract on metabolic and cardiopulmonary responses during a high-intensity interval exercise (HIIE), and its consequence on neuromuscular fatigue. Methods Ten healthy men underwent a HIIE (4 x 4 min, 3 min recovery) one hour after ingesting 400 mg of Maytenus ilicifolia extract (MIE) or placebo. Oxygen uptake (O2), dioxide carbon production (CO2), ventilation (E) and heart rate (HR) were measured throughout the HIIE. Maximal voluntary contraction (MVC), voluntary activation (VA), and evoked 1, 10 and 100 Hz force twitch were measured before supplementation (baseline), and before (pre-HIIE) and after the HIIE (post-HIIE). Results The O2, E, E/O2 ratio and HR increased progressively throughout the HIIE under both conditions (p < 0.05). MIE increased HR, however, at bouts 1 and 2 and mean O2 during HIIE. The mean respiratory exchange ratio during recovery was also reduced with MIE (p < 0.05). MVC and evoked force at 1, 10 and 100 Hz declined similarly after HIIE, regardless of the condition (MIE: −18 ± 17%, −50 ± 15%, −61 ± 13% and −34 ± 10% vs. placebo: −19 ± 15%, −48 ± 16%, −58 ± 12 and −29 ± 11%, respectively, p < 0.05). There was no effect of exercise or MIE on VA (p > 0.05). Conclusion MIE increases heart rate in the first bouts and mean oxygen uptake during HIIE without changes in neuromuscular fatigue development.

Mechanical, Physiological, and Perceptual Demands of Repeated Power Ability Lower-Body and Upper-Body Tests in Youth Athletes: Somatic Maturation as a Factor on the Performance.

This study aims (a) to assess and compare the acute mechanical, physiological, and perceptual demands induced by a lower and upper body repeated power ability (RPA) protocols, and (b) to examine how the somatic maturation could predict training response in RPA. Thirteen young male basketball players (chronological age = 15.2 ± 1.1 years; height = 173.8 ± 9.5 cm; body mass = 71.7 ± 18.3 kg) were selected to perform the parallel Back Squat (BS), and Bench Press (BP) RPA protocols (3 blocks of 5 sets of 5 repetitions with 30 s and 3 min of passive recovery between sets and blocks, respectively). Mean propulsive power (MPP), accelerometer-based data, cardio-respiratory data, blood lactate, rate of perceived exertion (RPE) and muscle soreness were recorded. Somatic maturation was estimated according to the Khamis and Roche method. On the BS protocol, the mean oxygen uptake (VO2), heart rate (HR), and RPE were 1006.33 ± 481.85 ml/min., 133.8 ± 12.5 bpm, and 6.14 ± 0.98 A.U., while on the BP protocol, were 684.6 ± 246.3 ml/min., 96.1 ± 10.4 bpm, and 5.08 ± 1.44 A.U., respectively. Significant between-blocks differences were found for MPP, RPE, and blood lactate for both exercises. The BS implies higher cardio-respiratory and perceptual demands, though lower power production fluctuation and movement variability than the BP. The somatic maturation was a strong predictor of RPA-derived variables in BS. The MPP during all protocol, and the MPP during the Best Set were significant predictable by somatic maturation in both exercises. Mechanical, physiological and perceptual training demands are exercise and maturation dependent.