Maximal Sprint Cycling Research Articles

The effect of ischemic preconditioning on repeated sprint cycling performance: a randomized crossover study.

Ischemic preconditioning (IPC) has been suggested to improve exercise performance by 1-8%. Prior research concerning its impact on short-duration exercises, such as sprints, has been limited and yielded conflicting results. The aim of this study, which included a non-occlusion-based placebo control, was to determine whether IPC improves repeated sprint performance in a manner that accounted for psychophysiological effects. Twenty-two healthy males participated in this study, which employed a randomized crossover design. Following the 10-min baseline period, participants received intervention under four different conditions: 1) no-intervention control (CON); 2) non-occlusion-based placebo control (SHAM); 3) remote IPC (RIPC); and 4) local IPC (LIPC). Participants then performed a standardized repeated sprint cycling (5×10s maximal cycling sprint, separated by a 40-s rest in each set). Repeated sprint performance, as indexed by average power output, peak power output, and total work, the improvement was observed in the RIPC and LIPC during the initial phase (set 1-3) when compared with CON (P<0.05). SHAM condition also showed an increase in peak power output in the set 1 (CON 9.97±1.05 vs. SHAM 10.30±1.13 w/kg, P<0.05), which may represent a psychophysiological component in the IPC-induced improvement. Higher lactate concertation was found in the SHAM and LIPC groups, than in the CON group, 5 minutes after the exercise (CON 15.72±0.68 vs. SHAM 16.82±0.41 vs. LIPC 17.19±0.39 mmol/L, P<0.0001 for both, respectively). In conclusion, LIPC enhanced repeated sprint cycling performance during the initial phase, beyond what could be accounted for entirely by a psychophysiological effect. The improvement associated with RIPC, however, did not surpass the effect of a placebo intervention.

The Influence of Pedaling Frequency on Blood Lactate Accumulation in Cycling Sprints.

Anaerobic performance diagnostics in athletes relies on accurate measurements of blood lactate concentration and the calculation of blood lactate accumulation resulting from glycolytic processes. In this study, we investigated the impact of pedaling frequency on blood lactate accumulation during 10-second maximal isokinetic cycling sprints. Thirteen trained males completed five 10-second maximal isokinetic cycling sprints on a bicycle ergometer at different pedaling frequencies (90 rpm, 110 rpm, 130 rpm, 150 rpm, 170 rpm) with continuous power and frequency measurement. Capillary blood samples were taken pre-exercise and up to 30 minutes post-exercise to determine the maximum blood lactate concentration.Blood lactate accumulation was calculated as the difference between maximal post-exercise and pre-start blood lactate concentration. Repeated measurement ANOVA with Bonferroni-adjusted post hoc t-tests revealed significant progressive increases in maximal blood lactate concentration and accumulation with higher pedaling frequencies (p<0.001; η2+>+0.782).The findings demonstrate a significant influence of pedaling frequency on lactate accumulation, emphasizing its relevance in anaerobic diagnostics. Optimal assessment of maximal lactate formation rate is suggested to require a pedaling frequency of at least 130 rpm or higher, while determining metabolic thresholds using the maximal lactate formation rate may benefit from a slightly lower pedaling frequency.

The influence of cadence on fatigue during maximal sprint cycling in world-class and elite sprint cyclists

ABSTRACT Optimising cadence through appropriate gear selection is a key consideration for track sprint cycling performance, yet the influence of cadence on fatigue (i.e., decrement in power output) within a maximal sprint is not well understood. The aim of this study was to identify the influence of cadence on fatigue during maximal sprint cycling. Eleven world-class and elite track sprint cyclists (n = 6 men, maximal power output (Pmax) = 1894 ± 351 W, optimal cadence (Fopt) = 134 ± 8 rev∙min−1: n = 5 women, Pmax = 1114 ± 80 W, Fopt = 124 ± 8 rev∙min−1) completed two testing sessions where power-cadence profiles were constructed to determine the Fopt associated with Pmax. Cyclists also performed three maximal 15-s sprints (Fopt, ±15%Fopt) to identify fatigue per pedal stroke across these cadence ranges. There was no significant difference (p = 0.2) in the absolute fatigue per pedal stroke when cadence was fixed 15% above (16.7 ± 6.1 W∙stroke−1) and below (15.3 ± 5.1 W∙stroke−1) Fopt. Similarly, there was no significant difference in the relative fatigue per pedal stroke (% peak power∙stroke−1) across Fopt and ± 15%Fopt trials (p = 0.12). The relative decrement in power output is equivalent across the ± 15%Fopt cadence range. As such, a higher-geared, lower-cadence approach to maximal sprint cycling could be a viable method to minimise maximal pedal strokes and reduce the decrement in power output.

The acute effects of concurrent endurance and resistance training on circulating microRNAs in trained rugby players

MicroRNA (miR) are small noncoding RNA involved in the post-transcriptional regulation of gene expression and may serve as biomarkers of muscle fatigue and muscle adaptations. The present study aimed to explore the acute responses of cycling vs. running endurance exercises within a concurrent endurance/resistance training on some specific miR. We hypothesized miR would acutely reveal greater muscle damage during the running endurance exercise as compared to cycling that would affect muscle protein synthesis biomarkers.Twenty-five trained rugby players participated in three randomized experimental sessions: 1) cycling endurance training session followed by a resistance session (CYCLE), 2) running endurance training session followed by a resistance session (RUN), and 3) a single resistance training session (CONTROL). Cycling and running endurance sessions were conducted in the morning and consisted in three sets of six 6-s maximal (cycling or running) sprints with 24 seconds passive recovery. Four hours later, volunteers conducted the resistance training (afternoon) composed of several upper- and lower-body strength exercises with heavy loads and low repetitions. During CONTROL, volunteers only performed the resistance training during the afternoon. Blood samples were collected before (PRE), immediately after (POST) and 3h after (POST3) the resistance training sessions. Extracellular vesicular miR were subsequently extracted and quantified using a real time quantitative PCR.The statistical analyses revealed that hsa-miR-203a-3p, hsa-miR-205-5p and hsa-miR-184 were not affected by our experimental procedures (p&gt;0.05). hsa-miR-9-5p and hsa-miR-1290 were significantly higher during CONTROL as compared to CYCLE (p=.033 and p=.039, respectively). hsa-miR-206 was significantly higher POST during RUN as compared to CYCLE and CONTROL (p=.018 and p=.014, respectively). hsa-miR-19-3p was significantly higher during RUN as compared to CONTROL (p=.38).Taken as a whole, our results revealed some differences in circulating miR as a result of a running endurance exercise as compared to no endurance or cycling endurance exercise. Confirming our a priori hypothesis, the higher values of circulating miR suggested greater muscle damage (i.e., hsa-miR-206) after running that could affect the muscle protein synthesis pathway expected by a subsequent resistance training session. Indeed, the higher hsa-miR-19-3p after RUN could have an inhibitory effect on Akt/mTOR. It is therefore suggested that conducting cycling endurance exercises within a concurrent training program could lower the likely interferences between endurance and resistance training in trained individuals. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A modified formula using energy system contributions to calculate pure maximal rate of lactate accumulation during a maximal sprint cycling test.

Purpose: This study aimed at comparing previous calculating formulas of maximal lactate accumulation rate ( ν La.max) and a modified formula of pure ν La.max (P ν La.max) during a 15-s all-out sprint cycling test (ASCT) to analyze their relationships. Methods: Thirty male national-level track cyclists participated in this study (n = 30) and performed a 15-s ASCT. The anaerobic power output (Wpeak and Wmean), oxygen uptake, and blood lactate concentrations (La-) were measured. These parameters were used for different calculations of ν La.max and three energy contributions (phosphagen, W PCr; glycolytic, W Gly; and oxidative, W Oxi). The P ν La.max calculation considered delta La-, time until Wpeak (tPCr-peak), and the time contributed by the oxidative system (tOxi). Other ν La.max levels without tOxi were calculated using decreasing time by 3.5% from Wpeak (tPCr -3.5%) and tPCr-peak. Results: The absolute and relative W PCr were higher than W Gly and W Oxi (p < 0.0001, respectively), and the absolute and relative W Gly were significantly higher than W Oxi (p < 0.0001, respectively); ν La.max (tPCr -3.5%) was significantly higher than P ν La.max and ν La.max (tPCr-peak), while ν La.max (tPCr-peak) was lower than P ν La.max (p < 0.0001, respectively). P ν La.max and ν La.max (tPCr-peak) were highly correlated (r = 0.99; R 2 = 0.98). This correlation was higher than the relationship between P ν La.max and ν La.max (tPCr -3.5%) (r = 0.87; R 2 = 0.77). ν La.max (tPCr-peak), P ν La.max, and ν La.max (tPCr -3.5%) were found to correlate with absolute Wmean and W Gly. Conclusion: P ν La.max as a modified calculation of ν La.max provides more detailed insights into the inter-individual differences in energy and glycolytic metabolism than ν La.max (tPCr-peak) and ν La.max (tPCr -3.5%). Because W Oxi and W PCr can differ remarkably between athletes, implementing their values in P ν La.max can establish more optimized individual profiling for elite track cyclists.

A Novel Approach to the Determination of Time- and Fatigue-Dependent Efficiency during Maximal Cycling Sprints.

During maximal cycling sprints, efficiency (η) is determined by the fiber composition of the muscles activated and cadence-dependent power output. To date, due to methodological limitations, it has only been possible to calculate gross efficiency (i.e., the ratio of total mechanical to total metabolic work) in vivo without assessing the impact of cadence and changes during exercise. Eliminating the impact of cadence provides optimal efficiency (ηopt), which can be modeled as a function of time. Here, we explain this concept, demonstrate its calculation, and compare the values obtained to actual data. Furthermore, we hypothesize that the time course of maximal power output (Pmax) reflects time-dependent changes in ηopt. Twelve elite track cyclists performed four maximal sprints (3, 8, 12, 60 s) and a maximal-pedaling test on a cycle ergometer. Crank force and cadence were monitored continuously to determine fatigue-free force-velocity profiles (F/v) and fatigue-induced changes in Pmax. Respiratory gases were measured during and for 30 min post-exercise. Prior to and following each sprint, lactate in capillary blood was determined to calculate net blood lactate accumulation (ΔBLC). Lactic and alactic energy production were estimated from ΔBLC and the fast component of excess post-exercise oxygen consumption. Aerobic energy production was determined from oxygen uptake during exercise. Metabolic power (MP) was derived from total metabolic energy (WTOT). ηopt was calculated as Pmax divided by MP. Temporal changes in Pmax, WTOT, and ηopt were analyzed by non-linear regression. All models showed excellent quality (R2 > 0.982) and allowed accurate recalculation of time-specific power output and gross efficiency (R2 > 0.986). The time-constant for Pmax(t) (τP) was closely correlated with that of ηopt (τη; r = 0.998, p < 0.001). Estimating efficiency using τP for τη led to a 0.88 ± 0.35% error. Although efficiency depends on pedal force and cadence, the latter influence can be eliminated by ηopt(t) using a mono-exponential equation whose time constant can be estimated from Pmax(t).

Identifying the Optimal Arm Priming Exercise Intensity to Improve Maximal Leg Sprint Cycling Performance.

Priming exercises improve subsequent motor performance; however, their effectiveness may depend on the workload and involved body areas. The present study aimed to estimate the effects of leg and arm priming exercises performed at different intensities on maximal sprint cycling performance. Fourteen competitive male speed-skaters visited a lab eight times, where they underwent a body composition measurement, two V̇O2max measurements (leg and arm ergometers), and five sprint cycling sessions after different priming exercise conditions. The five priming exercise conditions included 10-minute rest (Control); 10-minute arm ergometer exercise at 20% V̇O2max (Arm 20%); 10-minute arm ergometer exercise at 70% V̇O2max (Arm 70%); 1-min maximal arm ergometer exercise at 140% V̇O2max (Arm 140%); and 10-min leg ergometer exercise at 70% V̇O2max (Leg 70%). Power outputs of 60-s maximal sprint cycling, blood lactate concentration, heart rate, muscle and skin surface temperature, and rating of perceived exertion were compared between the priming conditions at different measurement points. Our results showed that the Leg 70% was the optimal priming exercise among our experimental conditions. Priming exercise with the Arm 70% also tended to improve subsequent motor performance, while Arm 20% and Arm 140% did not. Mild elevation in blood lactate concentration by arm priming exercise may improve the performance of high-intensity exercise.

Applications of near-infrared spectroscopy in "anaerobic" diagnostics - SmO2 kinetics reflect PCr dephosphorylation and correlate with maximal lactate accumulation and maximal pedalling rate.

We investigated the relationship of the time-dependent behaviour of muscle oxygen saturation SmO2(t), phosphagen energy supply WPCr(t) and blood lactate accumulation ΔBLC(t) during a 60-s all-out cycling sprint and tested SmO2(t) for correlations with the end of the fatigue-free state tFf, maximal pedalling rate PRmax and maximal blood lactate accumulation rate v̇Lamax. Nine male elite track cyclists performed four maximal sprints (3, 8, 12, 60 s) on a cycle ergometer. Crank force and cadence were monitored continuously to determine PRmax and tFf based on force-velocity profiles. SmO2 of the vastus lateralis muscle and respiratory gases were measured until the 30th minute after exercise. WPCr was calculated based on the fast component of the post-exercise oxygen uptake for each sprint. Before and for 30 minutes after each sprint, capillary blood samples were taken to determine the associated ΔBLC. Temporal changes of SmO2, WPCr and ΔBLC were analysed via non-linear regression analysis. v̇Lamax was calculated based on ΔBLC(t) as the highest blood lactate accumulation rate. All models showed excellent quality (R2 > 0.95). The time constant of SmO2(t) τSmO2 = 2.93 ± 0.65 s was correlated with the time constant of WPCr(t) τPCr = 3.23 ± 0.67 s (r = 0.790, p < 0.012), v̇Lamax = 0.95 ± 0.18 mmol · l-1 · s-1 (r = 0.768, p < 0.017) and PRmax = 299.51 ± 14.70 rpm (r = -0.670, p < 0.049). tFf was correlated with τSmO2 (r = 0.885, p < 0.001). Our results show a time-dependent reflection of SmO2 kinetics and phosphagen energy contribution during a 60-s maximal cycling sprint. A high v̇Lamax results in a reduction, a high PRmax in an increase of the desaturation rate. The half-life of SmO2 desaturation indicates the end of the fatigue-free state.

Active warm-up and time-of-day effects on repeated-sprint performance and post-exercise recovery.

This study investigated the effects of both an active warm-up and the time-of-day variation on repeated-sprint performance. A second objective was to compare the post-exercise recovery between theexperimentalconditions. Eleven male participants performed ten maximal cycling sprints (6s each, with a 30-s interval between them) in the morning and late afternoon, either after a warm-up or control condition. The warm-up consisted of cycling for 10min at 50% of the peak aerobic power. Rest measurements of rectal, muscle, and skin temperatures were higher in the afternoon compared to the morning (p < 0.05), with no significant differences in heart rate (p = 0.079) and blood lactate concentration (p = 0.300). Warm-up increased muscle temperature, heart rate, and lactate, and reduced skin temperature (all p < 0.001), though no significant differences were observed for rectal temperature (p = 0.410). The number of revolutions (p = 0.034, ηp2 = 0.375), peak (p = 0.034, ηp2 = 0.375), and mean (p = 0.037, ηp2 = 0.365) power of the first sprint (not the average of ten sprints) were higher in the afternoon compared to the morning, regardless of warm-up. However, beneficial performance effects of warming up were evident for the first (p < 0.001) and the average of ten sprints (p < 0.05), regardless of time of day. More remarkable changes during the 60-min post-exercise were observed for rectal temperature (p = 0.005) and heart rate (p = 0.010) in the afternoon than in the morning. Warming-up and time-of-day effects in enhancing muscular power are independent. Although warm-up ensured further beneficial effects on performance than the time-of-day variation, a faster post-exercise recovery was observed in the late afternoon.

Repeated-sprint training in heat and hypoxia: effect of exercise-to-rest ratio

The aim of this study was to investigate acute performance and physiological responses to the manipulation of exercise-to-rest ratio (E:R) during repeated-sprint hypoxic training (RSH) in hot conditions. Twelve male team-sport players completed two experimental sessions at a simulated altitude of ∼3000 m (FIO2 0.144), air temperature of 40°C and relative humidity of 50%. Exercise involved either 3×5×10-s (E:R1:2) or 3×10×5-s (E:R1:4) maximal cycling sprints interspersed with active recoveries at 120W (20-s between sprints, 2.5 and 5-min between sets for E:R1:2 and E:R1:4 respectively). Sessions were matched for overall sprint and total session duration (47.5-min). Peak and mean power output, and total work were greater in E:R1:4 than E:R1:2 (p < 0.05). Peak core temperature was significantly higher in E:R1:4 than E:R1:2 (38.44 ± 0.33 vs. 38.20 ± 0.35°C, p = 0.028). Muscle deoxygenation magnitude during sprints was greater in E:R1:2 (28.2 ± 1.6 vs. 22.4 ± 4.6%, p < 0.001), while muscle reoxygenation did not differ between conditions (p > 0.05).These results indicate E:R1:4 increased mechanical power output and core temperature compared to E:R1:2. Both protocols had different effects on measures of muscle oxygenation, with E:R1:2 generating greater muscle oxygen extraction and E:R1:4 producing more muscle oxygenation flux, which are both important signals for peripheral adaptation. We conclude that the E:R manipulation during RSH in the heat might be used to target different physiological and performance outcomes, with these findings forming a strong base for future mechanistic investigation.

Reliability and Validity of the Kickboxing Anaerobic Speed Test

ABSTRACT Purpose: This study investigated the test-retest reliability and discriminant validity of the Kickboxing Anaerobic Speed Test (KAST) and established a comparison with the maximal cycling sprint test (MCST). Methods: Forty-two male kickboxing athletes (18 elite and 24 sub-elite) participated in this study. Kickboxers performed the tests in both single and multiple forms. The KASTsingle was composed of kicks and punches, performed as quickly as possible until 5 reps of a 4 techniques’ combination (i.e., straight left punch, right-roundhouse kick, straight right punch, and left-roundhouse kick) were completed. The MCSTsingle was composed by a single 6-s maximal effort. The KASTmultiple was performed using 5 sequential sets of the single form following a 10s rest interval between sets. The MCSTmultiple was performed using 5 × 6 s repeated cycling efforts with 10s rest intervals. The tests and retests were carried out on separate occasions. To establish the test’s discriminatory capability, elite and sub-elite athletes were compared. Results: All tests’ performance scores showed excellent relative and absolute reliability (ICC > 0.900, SEM ≤ 0.98 s for KASTs and ≤ 0.74 W•kg−1 for MCST tests). Significant correlations between the identical versions were “large” (r > 0.70). Receiving operating characteristic analyses indicated that the KASTs and cycling tests were able to effectively discriminate between elite and sub-elite kickboxers. Additionally, the findings showed that KASTsingle, MCSTsingle, KASTmultiple, and MCSTmultiple correctly classified the groups by 78.6%, 73.6%, 88.1%, and 78.6%, respectively. Conclusions: This study supported the test-retest reliability and the discriminant validity of the KASTsingle and KASTmultiple to evaluate kickboxing athletes.

Repeated-Sprint Exercise in the Heat Increases Indirect Markers of Gastrointestinal Damage in Well-Trained Team-Sport Athletes.

Athletes engaged in repeated-sprint training in the heat can be at an increased risk of gastrointestinal ischemia and damage in response to a redistribution of blood to working skeletal muscles and the skin. This study investigated the effects of repeated sprinting in hot and cool conditions on markers of gastrointestinal damage. Twenty-five, well-trained, nonheat acclimated male team-sport athletes completed a five-session, repeated-sprint training regimen over 7 days in either HOT (40 °C and 40% relative humidity [RH]) or COOL (20 °C and 40% RH) conditions. Participants underwent a 20-min warm-up and four sets of 5 × 6-s maximal cycling sprints, with 24-s rest and 5-min recovery between sets. Venous blood was collected pre-, post-, and 1hr postexercise and analyzed for intestinal fatty acid binding protein, lipopolysaccharide binding protein, soluble CD14, and heat-shock protein. Intestinal fatty acid binding protein concentrations were significantly increased (p < .004) postexercise (593 and 454pg/ml) and 1hr postexercise (466 and 410pg/ml) on both Days 1 and 5 in HOT. Soluble CD14 increased by 398 and 308ng/ml postexercise (p = .041), and lipopolysaccharide binding protein increased by 1,694ng/ml postexercise on Day 1 in HOT (p < .05) and by 1,520ng/ml on Day 5 in COOL (p = .026). Core and skin temperature, rating of perceived exertion, and thermal sensation were higher (p < .05) in HOT on Days 1 and 5 during sprinting. Repeated sprinting in the heat induced greater thermal strain and mild changes in gastrointestinal damage, likely attributable to the combination of environmental conditions and maximal-intensity exercise.

Case Analysis of Sprint Interval Training for Adolescents With Severe Mental Illness

Case Analysis of Sprint Interval Training for Adolescents With Severe Mental Illness

Effects of carbohydrate-electrolyte dissolved alkaline electrolyzed water on physiological responses during exercise under heat stress in physically active men.

PurposeThis study investigated the effects of 1400 mL intake of alkaline electrolyzed water (AEW) or purified water (PW) into which carbohydrate-electrolyte (CE) was dissolved on improving physiological responses during exercise under heat stress.MethodsThis double-blinded, crossover randomized controlled trial included 10 male participants who completed two exercise trials in a hot environment (35 °C, ambient temperature, and 50% relative humidity) after consuming CE-dissolved PW (P-CE) or CE-dissolved AEW (A-CE). The exercise trial consisted of running for 30 min on a treadmill (at an intensity corresponding to 65% of heart rate reserve adjusted for heat stress conditions) and repeated sprint cycling (10 × 7-s maximal sprint cycling), with a 35-min rest interval between the two exercises, followed by a 30-min post-exercise recovery period. Before and after running, and after cycling, the participants drank P-CE (hydrogen concentration of 0 ppm, pH 3.8) or A-CE (0.3 ppm, pH 4.1). Blood samples were obtained before, during (rest interval between running and cycling), and post-exercise.ResultsRepeated sprint performance and oxidative stress response did not differ between the P-CE and A-CE trials. A-CE consumption significantly attenuated the increase in blood lactate concentration during the running exercise but not during repeated sprint cycling under heat stress conditions.ConclusionOur findings suggested that A-CE did not significantly affect repeated sprint performance; however, the attenuated elevation in blood lactate by A-CE ingestion implies a partial enhancement of endurance performance during submaximal exercise under heat stress.

Increased air temperature during repeated-sprint training in hypoxia amplifies changes in muscle oxygenation without decreasing cycling performance

ABSTRACT The present study aims to investigate the acute performance and physiological responses, with specific reference to muscle oxygenation, to ambient air temperature manipulation during repeated-sprint training in hypoxia (RSH). Thirteen male team-sport players completed one familiarisation and three experimental sessions at a simulated altitude of ∼3000 m (FIO2 0.144). Air temperatures utilised across the three experimental sessions were: 20°C, 35°C and 40°C (all 50% relative humidity). Participants performed 3 × 5 × 10-s maximal cycle sprints, with 20-s passive recovery between sprints, and 5 min active recovery between sets. There were no differences between conditions for cycling peak power, mean power, and total work (p>0.05). Peak core temperature (Tc) was not different between conditions (38.11 ± 0.36°C). Vastus lateralis muscle deoxygenation during exercise and reoxygenation during recovery was of greater magnitude in 35°C and 40°C than 20°C (p<0.001 for all). There was no condition × time interaction for Tc, skin temperature, pulse oxygen saturation, heart rate, rating of perceived exertion and thermal sensation (P>0.05). Exercise-induced increases in blood lactate concentration were higher in 35°C and 40°C than 20°C (p=0.010 and p=0.001, respectively). Integrating ambient temperatures up to 40°C into a typical RSH session had no detrimental effect on performance. Additionally, the augmented muscle oxygenation changes experienced during exercise and recovery in temperatures ≥35°C may indicate that the potency of RSH training is increased with additional heat. However, alterations to the training session may be required to generate a sufficient rise in Tc for heat training purposes. Highlights Heat exposure (35-40°C) did not affect mechanical performance during a typical RSH session. This indicates hot ambient temperature can be implemented during RSH, without negative consequence to training output. Hotter ambient conditions (35-40°C) likely result in greater muscle oxygenation changes during both exercise and recovery compared to temperate conditions. Although hotter sessions were perceived as more difficult and more thermally challenging, they did not further elevate Tc beyond that of temperate conditions. Accordingly, if intended to be used for heat acclimation purposes, alterations to the session may be required to increase heat load.

A Combined Hot and Hypoxic Environment during Maximal Cycling Sprints Reduced Muscle Oxygen Saturation: A Pilot Study

The present study investigated the effects of a combined hot and hypoxic environment on muscle oxygenation during repeated 15-s maximal cycling sprints. In a single-blind, cross-over study, nine trained sprinters performed three 15-s maximal cycling sprints interspersed with 7-min passive recovery in normoxic (NOR; 23℃, 50%, FiO2 20.9%), normobaric hypoxic (HYP; 23℃, FiO2 14.5%), and hot normobaric hypoxic (HH; 35℃, FiO2 14.5%) environments. Relative humidity was set to 50% in all trials. The vastus lateralis muscle oxygenation was evaluated during exercise using near-infrared spectroscopy. The oxygen uptake (VO2) and arterial oxygen saturation (SpO2) were also monitored. There was no significant difference in peak or mean power output among the three conditions. The reduction in tissue saturation index was significantly greater in the HH (-17.0 ± 2.7%) than in the HYP (-10.4 ± 2.8%) condition during the second sprint (p < 0.05). The average VO2 and SpO2 were significantly lower in the HYP (VO2 = 980 ± 52 mL/min, SpO2 = 82.9 ± 0.8%) and HH (VO2 = 965 ± 42 mL/min, SpO2 = 83.2 ± 1.2%) than in the NOR (VO2 = 1149 ± 40 mL/min, SpO2 = 90.6 ± 1.4%; p < 0.05) condition. In conclusion, muscle oxygen saturation was reduced to a greater extent in the HH than in the HYP condition during the second bout of three 15-s maximal cycling sprints, despite the equivalent hypoxic stress between HH and HYP.

Augmented muscle glycogen utilization following a single session of sprint training in hypoxia.

This study determined the effect of a single session of sprint interval training in hypoxia on muscle glycogen content among athletes. Ten male college track and field sprinters (mean ± standard error of the mean: age, 21.1 ± 0.2years; height, 177 ± 2cm; body weight, 67 ± 2kg) performed two exercise trials under either hypoxia [HYPO; fraction of inspired oxygen (FiO2), 14.5%] or normoxia (NOR: FiO2, 20.9%). The exercise consisted of 3 × 30s maximal cycle sprints with 8-min rest periods between sets. Before and immediately after the exercise, the muscle glycogen content was measured using carbon magnetic resonance spectroscopy in vastus lateralis and vastus intermedius muscles. Moreover, power output, blood lactate concentrations, metabolic responses (respiratory oxygen uptake and carbon dioxide output), and muscle oxygenation were evaluated. Exercise significantly decreased muscle glycogen content in both trials (interaction, P = 0.03; main effect for time, P < 0.01). Relative changes in muscle glycogen content following exercise were significantly higher in the HYPO trial (- 43.5 ± 0.4%) than in the NOR trial (- 34.0 ± 0.3%; P < 0.01). The mean power output did not significantly differ between the two trials (P = 0.80). The blood lactate concentration after exercise was not significantly different between trials (P = 0.31). A single session of sprint interval training (3 × 30s sprints) in hypoxia caused a greater decrease in muscle glycogen content compared with the same exercise under normoxia without interfering with the power output.

Listening to Fast-Tempo Music During a Post-Exercise Passive Rest Period Improved Subsequent Sprint Cycling.

Listening to music during active recovery between exercise bouts has been found to help maintain high levels of exercise performance; however, the effect of listening to music alone with no exercise while resting passively has not been elucidated. We examined whether listening to music during static (passive) recovery affects subsequent repeated sprint performances and/or psychological and physiological responses in healthy young males. Twelve healthy young male athletes completed two consecutive sets of 7 × 7 second maximal cycling sprints with a 30-second rest interval between the sprints. During a 15-minute interval between the sets, the participants rested passively while listening to fast-tempo (Fast, 130 bpm), slow-tempo (Slow, 70 bpm) music, or no music (Con). We assessed affective valence and arousal using the Affect Grid. The valence and arousal scores immediately after listening to fast-tempo music were significantly higher than those in the no music condition. Mean and peak power outputs during the second set after listening to fast-tempo music were significantly higher compared to those after the Slow and Con conditions (both adjusted p < .05). Moreover, the changes in exercise performances between the first and second set were significantly associated with changes in the arousal score induced by the music conditions, but not with changes in the valence score. These results suggested that listening to fast-tempo songs during passive recovery between the exercises improved subsequent repeated sprint cycling performance in physically active males. This type of rapid exercise recovery might be useful for competitive athletes, such as judo, track and fields, and swimming races.

Physiological responses to maximal 4s sprint interval cycling using inertial loading: the influence of inter-sprint recovery duration.

Interval exercise allows very high-power outputs to be maintained, a key for stimulating training adaptations. The main purpose of this study was to develop a sprint interval protocol that stimulated both anaerobic and aerobic systems while maximizing power output and minimizing fatigue. The secondary goal was to investigate the influence of inter-sprint recovery duration. Sixteen (8 females) participants (age: 23.5 ± 3.4 years, peak oxygen consumption (VO2peak): 45.6 ± 9.2mlkg-1min-1) took part in this study. The exercise protocol involved 30 bouts of 4s maximal cycling sprints using an 'Inertial Load Ergometer'. Recovery durations between sprints of 15, 30 and 45s were studied in three trials. Peak power output (PPO) was maintained while taking 45 and 30s of recovery, although it was 9% higher (p < 0.05) during 45 vs. 30s. PPO with 15s recovery declined 18% (p < 0.05) and then stabilized as did oxygen consumption (72±2% VO2peak) at a level that might reflect the peak rate of ATP-PC resynthesis from oxidative metabolism. The 15-, 30-, and 45s trials elicited 72, 56, and 49% VO2peak and 86, 80, and 75% of maximal heart rate (all p<0.001). Perceived exertion increased with shorter recovery periods but remained at 12.6-14.7 and never became 'very hard'. The present study describes the use of an inertial-load ergometer to accommodate repeated 4s maximal cycling sprints that elicit 72% VO2peak when the recovery period is 15s. However, a recovery duration of 15s was insufficient for the maintenance of power generation. NCT04448925, 26 Jun 2020; retrospectively registered to clinicaltrials.gov.

Are the Parameters of Novel Two-Point Force-Velocity Model Generalizable in Leg Muscles?

The two-point force-velocity model allows the assessment of the muscle mechanical capacities in fast, almost fatigue-free conditions. The aim of this study was to investigate the concurrent validity of the two-point parameters with directly measured force and power and to examine the generalization of the two-point parameters across the different functional movement tests of leg muscles. Twelve physically active participants were tested performing three functional lower limb maximal tests under two different magnitudes of loads: countermovement jumps, maximal cycling sprint, and maximal force under isokinetic conditions of the knee extensors. The results showed that all values from the two-point model were higher than the values from the standard tests (p < 0.05). We also found strong correlations between the same variables from different tests (r ≥ 0.84; p < 0.01), except for force in maximal cycling sprint, where it was low and negligible (r = −0.24). The results regarding our second aim showed that the correlation coefficients between the same two-point parameters of different lower limb tests ranged from moderate to strong (r −0.47 to 0.72). In particular, the relationships were stronger between power variables than between force variables and somewhat stronger between standard tests and two-point parameters. We can conclude that mechanical capacities of the leg muscles can be partially generalized between different functional tests.