Mean Power Output Research Articles

Effect of Acute Sodium Bicarbonate and Caffeine Coingestion on Repeated-Sprint Performance in Recreationally Trained Individuals: A Randomized Controlled Trial.

The acute and isolated ingestion of sodium bicarbonate (NaHCO3) and caffeine (CAF) improves performance and delays fatigue in high-intensity tasks. However, it remains to be elucidated if the coingestion of both dietary supplements stimulates a summative ergogenic effect. This study aimed to examine the effect of the acute coingestion of NaHCO3 and CAF on repeated-sprint performance. Twenty-five trained participants (age: 23.3 [4.0]y; sex [female/male]: 12/13; body mass: 69.6 [12.5]kg) participated in a randomized, double-blind, placebo (PLA) -controlled, crossover study. Participants were assigned to 4 conditions: (1)NaHCO3 + CAF, (2)NaHCO3, (3)CAF, or(4)PLA. Thus, they ingested 0.3g/kg of NaHCO3, 3mg/kg of CAF, or PLA. Then, participants performed 4 Wingate tests (Wt), consisting of a 30-second all-out sprint against an individualized resisted load, interspersed by a 1.5-minute rest period between sprints. Peak (Wpeak) and mean (Wmean) power output revealed a supplement and sprint interaction effect (P = .009 and P = .049, respectively). Compared with PLA, NaHCO3 + CAF and NaHCO3 increased Wpeak performance in Wt 3 (3%, P = .021) and Wt 4 (4.5%, P = .047), while NaHCO3 supplementation increased mean power performance in Wt 3 (4.2%, P = .001). In Wt 1, CAF increased Wpeak (3.2%, P = .054) and reduced time to Wpeak (-8.5%; P = .008). Plasma lactate showed a supplement plus sprint interaction (P < .001) when NaHCO3 was compared with CAF (13%, P = .031) and PLA (23%, P = .021). To summarize, although the isolated ingestion of CAF and NaHCO3 improved repeated-sprint performance, the coingestion of both supplements did not stimulate a synergic ergogenic effect.

V̇O2PEAK PROVIDES A BETTER PREDICTOR OF ERGOMETER MEAN MAXIMAL POWER THAN MAXIMAL OXYGEN EXTRACTION IN TRAINED ROWERS

INTRODUCTION &amp; AIMS Muscle oxygenation characteristics are suggested to better explain performance than peak oxygen uptake (V̇O2peak) in highly trained canoe-kayak athletes (Paquette et. al, 2018), but this has not been explored with rowers. Therefore, this investigation aimed to 1) determine whether maximal oxygen extraction improved prediction of rowing ergometer mean maximal power (MMP; W/kg) compared to V̇O2peak alone, and 2) assess differences in muscle oxygen extraction between anatomical sites during incremental rowing. METHODS Trained male (n=16) and female (n=6) rowers completed a 7x4min graded exercise test on a rowing ergometer to determine mean power output for each stage and V̇O2peak and MMP during the final stage. Change in muscle oxygen extraction (Δ[HHb]) during each stage was determined using near infrared spectroscopy (NIRS) at the vastus lateralis (VL), gastrocnemius medialis (GM), and biceps brachii (BB). The best predictor of MMP was determined using linear regression, and mixed-effects models were used to assess Δ[HHb] across sites and stage. RESULTS V̇O2peak was a significant predictor of MMP (R2=0.74); however, Δ[HHb] (at each site individually or combined) had no association with MMP (R2≤0.05). The strongest model included V̇O2peak and GM Δ[HHb] (R2=0.83); however, the improvement in model fit was modest (mean absolute error decreased from 0.211W.kg-1 to 0.193W.kg-1). A significant site x stage interaction was observed for Δ[HHb] at each site across all stages. Post-hoc analysis revealed VL Δ[HHb] was higher than GM Δ[HHb] for each stage; VL Δ[HHb] was lower than BB Δ[HHb] from stages 1-4, then higher from stages 5-7; and GM Δ[HHb] was lower than BB Δ[HHb] for stages 1-6, but higher in the final stage. CONCLUSION Maximal oxygen extraction alone cannot predict ergometer MMP in trained rowers. However, NIRS derived muscle oxygen extraction may provide additional useful information regarding relative muscle contributions at varying exercise intensities.

THE EFFECT OF DRY AND HUMID HEAT ACCLIMATION ON PERFORMANCE IN EACH ENVIRONMENT

BACKGROUND Athletes adopt heat acclimation (HA) to partly restore heat-mediated decrements in performance. However, the influence of environmental characteristics during HA on performance in dry and humid conditions is unclear. Therefore, this study aimed to compare dry and humid HA on performance in each environment. METHODS In a counterbalanced crossover study, ten trained male cyclists (age 43 ± 9 y; body mass 80.8 ± 7.3 kg; maximal oxygen uptake; 59 ± 7 mL.kg-1.min-1) completed a 30-min time-trial in hot-dry (TT-DRY; 42°C, 25% RH) and warm-humid (TT-HUM; 33°C, 80% RH) conditions before and after 8 days of controlled heart rate (HR) HA in either dry (DRY-HA) or humid conditions (HUM-HA). A Bayesian multi-level model was used to determine posterior means, 90% credible intervals, and probability of direction (%). RESULTS The improvement in power output during TT-HUM was similar following DRY-HA (13 W [3, 22]; 99%) and HUMID-HA (11 W [3, 19]; 98%). In TT-DRY, the improvement in power output was 12 W ([1, 22]; 97%) higher following DRY-HA (19 W [10, 28]; &amp;gt;99%) compared to HUM-HA (7 W [-2, 17]; 91%). During TT-HUM, mean rectal temperature changed following HUM-HA (0.03°C [-0.11, 0.17]; 63%) and DRY-HA (-0.14°C [-0.29, 0.02]; 92%), with a difference of 0.16°C ([-0.36, 0.03]; 92%). During TT-DRY, the difference was -0.20°C ([-0.40, 0.01]; 94%) between HUM-HA (-0.22°C [-0.38, -0.06]; 98%) and DRY-HA (-0.03°C [-0.19, 0.13]; 63%). Mean HR during TT-DRY (3 beats·min-1 [-2, 8]; 85%) and TT-HUM (-4 beats·min-1 [-10, 2]; 85%) was similar following DRY-HA and HUM-HA. CONCLUSIONS DRY-HA further improved mean power output during TT-DRY compared to HUM-HA. However, HUM-HA tended to lower rectal temperature more than DRY-HA during TT-DRY. HA condition did not influence HR during either TT. Our data indicate that performance is further improved in hot-dry conditions when acclimating to the same environment.

Renewable Energy Complementarity (RECom) maps – a comprehensive visualisation tool to support spatial diversification

Abstract. Maps showing the mean wind speed only give an inaccurate indication of the quality of locations for future wind power developments. Calculating the capacity factor and plotting that on a map gives a better indication of the expected mean power output, but the outcome depends on the turbine choice. In this article, we introduce a general step-by-step method for improved visualisation of potential wind power locations. First, the mentioned dependency on turbine choice is compensated for by putting the expected mean power output in relation to the expected mean power output of all other wind parks of the region. This relative capacity factor results in comprehensive wind resource maps and can be plotted for the situation today and also for a future scenario. Since the expected income of a potential wind park is the product of mean power output and mean market value, looking at the relative capacity factor only does not give the full picture. The mean market value is influenced by the merit order effect that is mainly driven by covariance with other wind parks and the capacity factor's relation to production at low-wind moments. A market value factor is introduced that captures the expected mean market value relative to other wind parks, based on a simplified power market model. Finally the Renewable Energy Complementarity (RECom) index is defined, combining the relative capacity factor and market value factor into a single index, resulting in RECom maps. This map can comprehensively show the revenue potential of different locations for potential future wind power developments.

The Impact of Range of Motion on Applied Force Characteristics and Electromyographic Activity during Repeated Sets of Bench Press Exercise.

This study examined the effects of range of motion (ROM) on applied force, power output and surface electromyographic (sEMG) responses during repeated sets of bench press exercise executed as fast as possible. Ten resistance trained men performed three sets to momentary failure with two-min rest intervals under three different ROM conditions: (a) full ROM (FULL), (b) TOP, at the top half of ROM, and (c) BOTTOM, at the bottom half of ROM. Mean and peak force were higher in TOP compared to FULL and BOTTOM (mean force: 817 ± 80 vs. 657 ± 98 vs. 623 ± 122 N, respectively, p < 0.001) with no differences between FULL and BOTTOM. During repeated sets, large decreases were found in peak (by 29.4 to 45.3%) and mean power (by 55.5 to 64.7%) from the first to the last repetitions. However, the decrease in mean force was only 2% (p < 0.01) and decreases in peak force ranged from 6.7 and 8.8% to zero, indicating the velocity loss was the main contributor to fatigue in power output. Although force and power output in set 3 were unchanged in BOTTOM, mean power output decreased significantly, suggesting that lower performance and fatigue may be related to the longer muscle length. Fatigue was accompanied by an increase in sEMG activity and a decrease in median frequency in all muscles, with triceps brachialis sEMG reflecting more the force and power differences among ROMs. In conclusion, fatigue depends on velocity rather than force loss during bench press exercise at different ROMs.

Enhancing Anaerobic Performance in Kickboxers: The Strategic Role of Short-Duration Napping

The intricate relationship between sleep and athletic performance has long been a subject of interest in sports science. This study delves into the specific impact of short-duration napping on anaerobic performance parameters in the study of kickboxing, an intense combat sport demanding both physical prowess and strategic acumen. We conducted a controlled investigation with 14 young elite male kickboxers, characterized by an average age of 20.29 ± 0.80 years, a height of 174.48 ± 4.11 cm, body masses of 70.46 ± 7.78 kg, and a body mass index (BMI) of 23.12 ± 2.02 kg/m². The experimental design encompassed three distinct conditions: no napping (N0), a 25-minute nap (N25), and a 45-minute nap (N45). The evaluation focused on several key performance metrics, including countermovement jump (CMJ), mean power, and peak power outputs. Intriguingly, our findings indicated that while CMJ values remained relatively unaffected by the napping conditions, significant variations were observed in both mean and peak power outputs, particularly among participants who napped. These variations suggest that napping, even for short durations, can significantly influence certain anaerobic performance parameters in kickboxers, with a marked improvement in power-related aspects. This research contributes to the expanding body of literature on the role of sleep and rest in athletic performance, specifically highlighting the potential of napping as an effective strategy for enhancing physical capabilities in combat sports. The implications of these findings extend beyond the realm of kickboxing, offering valuable insights and practical applications for athletic training and performance optimization across various sports disciplines where anaerobic capabilities are crucial.

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.

Continuous blood flow restriction during repeated-sprint exercise increases peripheral but not systemic physiological and perceptual demands.

This study examined the impact of continuous blood flow restriction (BFR) during repeated-sprint exercise (RSE) on acute performance, peripheral, systemic physiological, and perceptual responses. In a randomized crossover design, 26 adult male semi-professional and amateur team-sport players completed two RSE sessions (3 sets of 5 × 5-s sprints with 25s of passive recovery and 3min of rest) with continuous BFR (45% arterial occlusion; excluding during between-set rest periods) or without (non-BFR). Mean and peak power output were significantly lower (p<0.001) during BFR compared to non-BFR (dz=0.85 and 0.77, respectively). Minimum tissue saturation index during the sprints and rest periods was significantly reduced (p<0.001) for BFR (dz=1.26 and 1.21, respectively). Electromyography root mean square was significantly decreased (p<0.01) for biceps femoris and lateral gastrocnemius muscles during BFR (dz=0.35 and 0.79, respectively), but remained unchanged for the vastus lateralis muscle in both conditions. Oxygen consumption and minute ventilation were significantly reduced (both p<0.01) for BFR (dz=1.46 and 0.43, respectively). Perceived limb discomfort was significantly higher (p<0.001) for BFR (dz=0.78). No differences (p>0.05) in blood lactate concentration or rating of perceived exertion were observed between conditions. Blood flow-restricted RSE reduced performance and likely increased the physiological and perceptual stimulus for the periphery with greater reliance on anaerobic glycolysis, despite comparable or decreased systemic demands.

Active ischemic pre-conditioning does not additively improve short-term high-intensity cycling performance when combined with caffeine ingestion in trained young men.

We investigated the effect of ischemic preconditioning (IPC) with and without caffeine supplementation on mean power output (MPO) during a 4-min cycling time-trial (TT). In a double-blinded, randomized, crossover-design, 11 trained men performed a TT on 4days separated by ∼1week. One hour before TT, participants ingested either caffeine (3mgkgbw-1) or placebo pills, after which femoral blood-flow was either restricted with occlusion cuffs inflated to ∼180mmHg (IPC), or sham-restricted (0-10mmHg; Sham) during 3×2-min low-intensity cycling (10% of incremental peak power output). Then, participants performed a standardized warm-up followed by the TT. Plasma lactate and K+ concentrations and ratings of perceived exertion (RPE) were measured throughout trials. TT MPO was 382±17W in Placebo+Sham and not different from Placebo+IPC (-1W; 95% CI: -9 to 7; p=0.848; d: 0.06), whereas MPO was higher with Caffeine+Sham (+6W; 95% CI: -2 to 14; p=0.115; d: 0.49) and Caffeine+IPC (+8W; 95% CI: 2-13; p=0.019; d: 0.79) versus Placebo+Sham. MPO differences were attributed to caffeine (caffeine main-effect: +7W; 95% CI: 2-13; p=0.015; d: 0.54. IPC main-effect: 0W; 95% CI: -6 to 7; p=0.891; d: 0.03; caffeine×IPC interaction-effect: p=0.580; d: 0.17). TT RPE and plasma variables were not different between treatments. In conlcusion, IPC with co-ingestion of placebo does not improve short-term high-intensity performance in trained men versus a double-placebo control (Placebo+Sham) and does not additively enhance performance with caffeine. These data do not support IPC as a useful strategy for athletes prior to competition but confirms caffeine's performance-enhancing effect.

Acute ingestion of Ibuprofen does not influence the release of IL-6 or improve self-paced exercise in the heat despite altering cortical activity

The present study tested the hypothesis that ingesting 800 mg Ibuprofen prior to self-paced cycling at a fixed rating of perceived exertion (RPE) improves performance by attenuating the release of Interleukin (IL)-6 and its signalling molecules, whilst simultaneously modulating cortical activity and cerebral oxygenation to the brain. Eight healthy, recreationally active males ingested 800 mg Ibuprofen or a placebo ~ 1 h prior to performing fixed RPE cycling for 60 min in 35 °C and 60% relative humidity at an intensity of hard to very hard (RPE = 16) with intermittent maximal (RPE = 20) sprints every 10 min. Power output (PO), core and mean skin temperatures (Tc, Tsk), respectively, and heart rate (HR) were measured continuously. Electroencephalography (EEG) recordings at the frontal (Fz), motor (Cz) and Parietal (Pz) areas (90 s) were collected every 5 min. IL-6, soluble glycoprotein receptor (sgp130) and IL-6 receptor (R) were collected at pre-, 30 min and immediately post-exercise. Mean PO, HR, Tc and Tsk, and RPE were not different between trials (P ≥ 0.33). At end-exercise, the change in IL-6, sgp130 and sIL-6R was not different between trials (P ≥ 0.12). The increase in α and β activity did not differ in any cortices between trials (P ≥ 0.07); however, there was a significant reduction in α/β activity in the Ibuprofen compared to placebo trials at all sites (P ≤ 0.05). Ingesting a maximal, over-the-counter dose of Ibuprofen prior to exercise in the heat does not attenuate the release of IL-6, nor improve performance, but may influence cortical activity evidenced by a greater reduction in α/β activity.

Three sessions of repeated sprint training in normobaric hypoxia improves sprinting performance

The objective of the present study was to evaluate the impacts of three-session repeated sprint training conducted in normobaric hypoxia with 48-h intervals on sprint performance, arterial oxygen saturation (SpO2), and rating of perceived exertion (RPE) scores. A total of 27 moderately trained male university students voluntarily took part in this study. In this single-blind placebo-controlled study, subjects were assigned into normobaric hypoxia (FiO2: 13.6%; HYP), normobaric normoxia (FiO2: 20.9%; PLA), and control group (CON). The HYP and PLA groups underwent three repeated sprint training sessions (a total of four sets of five times 5-s sprints with a 5-min rest between sets and a 30-s rest between each sprint) on a cycle ergometer in normobaric hypoxia or normoxia conditions. Pre- and post-tests were performed 72 h before and after the training period. Three participants were excluded from the study, and the data from twenty-four participants were analyzed. Contrary to what was observed in the pre and post tests, no time and condition interactions were observed in the relative peak power output (PPO), mean power output (MPO), percentage of sprint decrement score (Sdec%), and RPE parameters. Time effect was found in all observed variables respectively; relative PPO (F = 5.784, p = 0.045, η2 = 0.74), relative MPO (F = 3.927, p = 0.042, η2 = 0.66) and large time effect found for Sdec% (F = 11.430, p = 0.046, 0.83), and RPE (F = 14.990, p = 0.008, η2 = 0.96). A notable increase in relative peak power output (PPO) and mean power output (MPO) was observed in the post-test in comparison to the pre-test values, indicating statistical significance. The increase in PPO was in HYP 13.44% (p = 0.006), in PLA 7.48% (p = 0.264) and in CON 2.66% (p = 0.088). The decrease in Sdec% was in HYP -13.34%% (p = 0.048), PLA -10.54 (p = 0.577) and CON -4.83 (p = 0.644) at post-test. The results show that although there were no statistical differences between the groups, notable differences in performance-related variables were observed in the HYP group after 3 sessions of repetitive sprint training in hypoxia.

Repeated-Sprint Training With Blood-Flow Restriction Improves Repeated-Sprint Ability Similarly to Unrestricted Training at Reduced External Loads.

This study examined performance and physiological adaptations following 3 weeks of repeated-sprint training (RST) with blood-flow restriction (BFR) or without (non-BFR). Twenty-six semiprofessional and amateur adult male team-sport players were assessed for repeated-sprint ability, anaerobic capacity, leg lean mass, neuromuscular function, and maximal aerobic capacity before and after RST. Participants completed 9 cycling RST sessions (3 sets of 5-7 × 5-s sprints, 25-s passive recovery, 3-min rest) over a 3-week period with BFR or non-BFR. During RST sessions, the BFR group demonstrated lower mean power output compared with non-BFR (-14.5%; g = 1.48; P = .001). Significant improvements (P < .05) in mean and peak power output during repeated-sprint ability (+4.1%; g = 0.42, and + 2.2%; g = 0.25, respectively) and anaerobic capacity (+4.8%; g = 0.47, and + 4.7%; g = 0.32, respectively) tests, leg lean mass (+2.0%; g = 0.16), and peak aerobic power (+3.3%; g = 0.25) were observed from pretesting to posttesting without any between-groups differences. No significant changes (P > .05) were observed for maximal isometric voluntary contraction and maximal aerobic capacity. Peak rate of force development decreased (P = .003) in both groups following RST (-14.6%; g = 0.65), without any between-groups differences. Repeated-sprint ability, anaerobic capacity, leg lean mass, and peak aerobic power improved following 3 weeks of RST; however, the addition of BFR did not further enhance adaptations. Interestingly, comparable improvements were achieved between groups despite lower external loads experienced during RST sessions with BFR.

Will Music Give Me Power? Effects of Listening to Music during Active and Passive Rest Intervals on Power Output during Resistance Exercise.

The study aimed to evaluate the impact of listening to preferred music during active/passive rest on power output and heart rate in barbell squats (BS) and bench presses (BP). Fifteen participants (13 males and 2 females), moderately resistance trained, were engaged in four randomized experimental sessions with varying rest intervals (active/passive) and music presence (listening or not). Each session involved three sets of three repetitions of BS and BP at a 50% one-repetition maximum. ANOVA showed a significant main effect of the set for BP relative mean and peak power output (p < 0.001; both). The post hoc comparisons indicated a significantly higher BP relative mean and peak power output in set_2 (p < 0.001; effect size [ES] = 0.12 and p < 0.001; ES = 0.10) and set_3 (p < 0.001; ES = 0.11 and p = 0.001; ES = 0.16) in comparison to set_1. Moreover, a main effect of the set indicating a decrease in BS relative peak power output across sets was observed (p = 0.024) with no significant differences between sets. A significantly higher mean heart rate during active rest in comparison to passive rest was observed (p = 0.032; ES = 0.69). The results revealed no significant effect of listening to music on relative power output and heart rate during BS and BP.

Echocardiographic assessment of myocardial efficiency predicts exercise performance

AbstractCardiac function is a major determinant of cardiopulmonary fitness. This study aimed to determine if novel echocardiographic myocardial function and efficiency parameters at rest can predict exercise performance during different types of prolonged high‐intensity endurance exercise. Echocardiography was performed before exercise in 40 healthy (75% males) 50.3 ± 9.1‐year‐old recreational athletes. Echocardiographic parameters at rest were compared with exercise performance assessed by power output during two different exercises: A lactate threshold and cardiopulmonary exercise test (La‐CPET) and a 91‐km mountain bike sport cycling race. The La‐CPET had a median duration of 43 (40, 45) minutes and a mean power output of 2.9 ± 0.5 W/kg. The race had a median duration of 236 (214, 268) minutes and a mean power output of 2.1 ± 0.5 W/kg. There was moderate left ventricular (LV) dilatation in individuals with the highest performance. The myocardial efficiency parameter, global wasted work (GWW), was positively correlated with race duration (rho = 0.42, p = 0.008) and negatively correlated with mean power output during both the La‐CPET (rho = −0.43, p = 0.007) and the race (rho = −0.44, p = 0.005). In multivariable models, including LV volumes, left GWW remained an independent predictor of race duration (beta = 0.40, p = 0.007) and of mean power output during the La‐CPET (beta = −0.40, p = 0.006) and the race (beta = −0.43, p = 0.003). The novel echocardiographic myocardial efficiency parameter, GWW, measured at rest, is an independent predictor of prolonged high‐intensity endurance exercise performance in healthy middle‐aged athletes. These findings suggest that resting myocardial efficiency parameters may aid the identification of exercise‐induced LV dilatation.

Shifting the Energy Toward Los Angeles: Comparing the Energetic Contribution and Pacing Approach Between 2000- and 1500-m Maximal Ergometer Rowing.

To compare the energetic contribution and pacing in 2000- and 1500-m maximal rowing-ergometer performances. On separate visits (>48 h apart, random order), 18 trained junior (16.7 [0.4]y) male rowers completed 3 trials: a7 × 4-minute graded exercise test, a2000-m time trial (TT2000), and a1500-m TT (TT1500). Respiratory gases were continuously measured throughout each trial. The submaximal power-to-oxygen-consumption relationship from the graded exercise test was used to determine the accumulated oxygen deficit for each TT. Differences in mean power output (MPO), relative anaerobic contribution, percentage of peak oxygen uptake, pacing index, maximum heart rate, rating of perceived exertion, and blood lactate concentration were assessed using linear mixed modeling. Compared to TT2000 (324 [24]W), MPO was 5.2% (3.3%) higher in TT1500 (341 [29W]; P < .001, ηp2=.70). There was a 4.9% (3.3%) increase (P < .001, ηp2=.71) in anaerobic contribution from 17.3% (3.3%) (TT2000) to 22.2% (4.3%) (TT1500). Compared to TT1500, maximum heart rate, rating of perceived exertion, and blood lactate concentration were all greater (P < .05) in TT2000. The pacing index was not different between trials. Percentage increase in MPO from TT2000 to TT1500 was negatively associated with pacing variance in TT1500 (R2 = .269, P = .027). Maximal ergometer performance over 1500m requires a significantly greater anaerobic contribution compared with 2000m. Junior male athletes adopt a consistent pacing strategy across both distances. However, those who experienced greater percentage increases in MPO over the shorter test adopted a more even pacing strategy. To prepare for 1500-m performance, greater emphasis should be placed on developing capacity for work in thesevere domain and completing race simulations with a more even pacing strategy.

Cannabis containing THC impairs 20-min cycling time trial performance irrespective of the method of inhalation.

Herein, we examine the human exercise response following cannabis inhalation, taking into consideration varied cannabinoid concentrations and different inhalation methods. A semirandomized crossover study design was used, with measures of perceived exertion and physiological responses to submaximal and maximal exercise. Participants (n = 14, 9 males 5 females) completed exercise after 1) smoking Δ-9-tetrahydrocannabinol (THC)-predominant cannabis (S-THC), 2) inhaling aerosol (vaporizing) from THC-predominant cannabis (V-THC), 3) inhaling aerosol from cannabidiol (CBD)-predominant cannabis (V-CBD), or 4) under control conditions. All exercise was performed on a cycle ergometer, with submaximal testing performed at 100 W followed by an evaluation of maximal exercise performance using an all-out 20-min time trial. Metabolism was characterized via the analysis of expired gases while subjective ratings of perceived exertion (RPE) were reported. During submaximal cycling, heart rate was higher during S-THC and V-THC compared with both control and V-CBD (all P < 0.02). During maximal exercise, V̇e was lower in V-THC compared with control, S-THC, and V-CBD (all P < 0.03), as was S-THC compared with control (P < 0.05). Both V̇o2 and RPE were similar between conditions during maximal exercise (both P > 0.1). Mean power output during the 20-min time trial was significantly lower in the S-THC and V-THC conditions compared with both control and V-CBD (all P < 0.04). Cannabis containing THC alters the physiological response to maximal and submaximal exercise, largely independent of the inhalation method. THC-containing cannabis negatively impacts vigorous exercise performance during a sustained 20-min effort, likely due to physiological and psychotropic effects. Inhalation of cannabis devoid of THC and primarily containing CBD has little physiological effect on the exercise response or performance.NEW & NOTEWORTHY Inhalation of cannabis containing THC alters physiological responses to both submaximal and maximal exercise and reduces mean power output during a 20-min time trial, regardless of whether it is inhaled as smoke or aerosol. In contrast, cannabis devoid of THC and predominantly containing CBD has no effect on physiological responses to exercise or performance.

Caffeine Mouth Rinse Plus Ingestion Improves the 10-Km Time Trial Compared to Caffeine Mouth Rinse Alone

ABSTRACT Background: The benefits of caffeine to physical performance have been extensively demonstrated, however, it has recently been speculated that there is an effect of the administration route on its effectiveness. Purpose: The current study investigated the effect of caffeine mouth rinse in isolation or combined with ingestion on performance in a 30-minute constant-load exercise followed by a 10-km cycling time trial. Methods: Ten physically active men performed a 30-minute constant-load exercise at 50% of the graded test Wmax, followed by a 10-km cycling time trial. Before and at the middle points of the constant-load exercise and 10-km cycling time trial, the following conditions were administered: PLA (cellulose ingestion plus mouth rinsing with magnesium sulfate), ING (5 mg.kg−1 of caffeine ingestion plus mouth rinsing with magnesium sulfate), MR (cellulose ingestion plus mouth rinsing with 1.2% caffeine), and COMB (5 mg.kg−1 of caffeine ingestion plus mouth rinsing with 1.2% caffeine). Results: During the 30-minute constant-load exercise, COMB presented a lower rating of perceived exertion (RPE) than MR (p = .04). For the 10-km time trial, the COMB was faster than MR (MR = 1363 ± 345 vs. COMB = 1291 ± 308s, Δ% = 5.57, p = .05). Mean power output was higher in COMB than PLA, ING, and MR (234 ± 15 vs. 169 ± 29, 148 ± 11, and 145 ± 12 W, respectively). There were no differences between conditions for heart rate and RPE during the 10-km time trial. Conclusion: In summary, caffeine mouth rinsing potentiated the effects of caffeine ingestion during the 10-km time trial compared to caffeine mouth rinsing alone.

Powering Toward Los Angeles: Comparing Power Output and Pacing Approach Between Maximal 2000- and 1500-m On-Water Racing in Elite Rowers.

To compare power output and pacing between maximal 1500- and 2000-m on-water rowing performances. Twenty-six (female n = 4, male n = 22) international rowers, across 6 boat classes, completed maximal 1500- and 2000-m on-water races, separated by 24 to 48hours. Crew combinations and seat orders remained consistent between races. Peach PowerLine instrumentation measured power output and stroke rate. Differences in completion time, mean power output (MPO), percentage prognostic velocity (PPV;percentage of world record velocity in each boat class), stroke rate, and pacing variance were assessed using linear mixed modeling. Compared with 2000-m, completion times were 90.4 (6.1) seconds shorter over 1500m (-24.7% [0.7%]). Both MPO (P = .255, ηp2=.06) and PPV (P = .340, ηp2=.18) were not different between distances. Broadly, crews adopted a reverse-J-shaped pacing across both distances, demonstrating a reduced variance over 1500m (P = .035, ηp2=.62). Percentage change in MPO from 2000 to 1500m demonstrated a strong negative association with pacing variance over 1500m (R2 = .74, P = .027). International rowing crews did not increase MPO or PPV when racing maximally over 1500m compared to 2000m. Comparable strategies were adopted over both distances, with less variance in pacing observed over 1500m. The crews that demonstrated greater increases in MPO over the shorter race employed a flatter pacing strategy. To improve 1500-m on-water performance, rowers may need to adopt a more even pacing approach.

Inter-individual variability in peripheral oxygen saturation and repeated sprint performance in hypoxia: an observational study of highly-trained subjects.

Individual variations in peripheral oxygen saturation (SpO2) during repeated sprints in hypoxia and their impact on exercise performance remain unclear despite fixed external hypoxic stimuli (inspired oxygen fraction: FiO2). This study examined SpO2 individual variations during repeated sprints in hypoxia and their impact on exercise performance. Thirteen highly-trained sprint runners performed 10 × 10-s cycle sprints with 30-s passive recoveries in normobaric hypoxia (FiO2: 0.150). Mean power output (MPO), post-sprint SpO2, and heart rate for each sprint were assessed. Sprint decrement score (Sdec), evaluating fatigue development, was calculated using MPO variables. Participants were categorized into a high saturation group (HiSat, n = 7) or a low saturation group (LowSat, n = 6) based on their mean post-sprint SpO2 (measured 10-15 s after each sprint). Individual mean post-sprint SpO2 ranged from 91.6% to 82.2%. Mean post-sprint SpO2 was significantly higher (P < 0.001, d = 1.54) in HiSat (89.1% ± 1.5%) than LowSat (84.7% ± 1.6%). A significantly larger decrease in Sdec (P = 0.008, d = 1.68) occurred in LowSat (-22.3% ± 2.3%) compared to HiSat (-17.9% ± 2.5%). MPO (P = 0.342 d = 0.55) and heart rate (P = 0.225 d = 0.67) did not differ between groups. There was a significant correlation (r = 0.61; P = 0.028) between SpO2 and Sdec. In highly-trained sprint runners, individual responses to hypoxia varied widely and significantly affected repeated sprint ability, with greater decreases in SpO2 associated with larger performance alterations (i.e., larger decrease in Sdec).

Physiological and molecular predictors of cycling sprint performance.

The study aimed to identify novel muscle phenotypic factors that could determine sprint performance using linear regression models including the lean mass of the lower extremities (LLM), myosin heavy chain composition (MHC), and proteins and enzymes implicated in glycolytic and aerobic energy generation (citrate synthase, OXPHOS proteins), oxygen transport and diffusion (myoglobin), ROS sensing (Nrf2/Keap1), antioxidant enzymes, and proteins implicated in calcium handling. For this purpose, body composition (dual-energy X-ray absorptiometry) and sprint performance (isokinetic 30-s Wingate test: peak and mean power output, Wpeak and Wmean ) were measured in young physically active adults (51 males and 10 females), from which a resting muscle biopsy was obtained from the musculus vastus lateralis. Although females had a higher percentage of MHC I, SERCA2, pSer16 /Thr17 -phospholamban, and Calsequestrin 2 protein expressions (all p < 0.05), and 18.4% lower phosphofructokinase 1 protein expression than males (p < 0.05), both sexes had similar sprint performance when it was normalized to body weight or LLM. Multiple regression analysis showed that Wpeak could be predicted from LLM, SDHB, Keap1, and MHC II % (R 2 = 0.62, p < 0.001), each variable contributing to explain 46.4%, 6.3%, 4.4%, and 4.3% of the variance in Wpeak , respectively. LLM and MHC II % explained 67.5% and 2.1% of the variance in Wmean , respectively (R 2 = 0.70, p < 0.001). The present investigation shows that SDHB and Keap1, in addition to MHC II %, are relevant determinants of peak power output during sprinting.