Effect of applied cadence in repeated sprint cycling on muscle characteristics.

PURPOSE: This study aimed to investigate physiological responses, muscle-tendon unit properties of the quadriceps muscle, and mechanical performance after repeated sprint cycling at optimal and 70% of optimal cadence. METHODS: Twenty recreational cyclists performed as first sprint performance cycling test and during subsequent sessions two repeated sprint cycling protocols at optimal and 70% of optimal cadence, in random order. The muscle-tendon unit outcome measures on the dominant leg included muscle thickness, fascicle length (Lf), pennation angle (θp), and stiffness for the rectus femoris (RF), vastus lateralis (VL), and vastus medialis muscle (VM) at baseline, immediately after repeated sprint cycling, and 1-h post-exercise. RESULTS: The results showed an increase in muscle thickness and θp in RF, VL, and VM for both cadences from baseline to immediately after exercise. The Lf decreased in RF (both cadences), while stiffness decreased in RF, VL, and VM at optimal cadence, and in VL at 70% of optimal cadence from baseline to immediately after exercise. CONCLUSION: The present study revealed that the alterations in muscle characteristics were more marked after repeated sprint cycling at optimal cadence compared with a lower cadence most likely as a result of higher load on the muscle-tendon unit at optimal cadence.

Fatigue-induced Alterations of the Patellar Tendon in Elite Sprint Track Cyclists.

This study aims to investigate morphological and mechanical properties and echogenicity of the patellar tendon (PT) after acute fatigue-induced alterations in sprint track cyclists. Fourteen elite track cyclists participated in this study. The exercise protocol consisted of three maximal start accelerations (over a distance of 62.5 m), one maximal start acceleration (at both 125 m and 250 m), and sprints from the standing start. Immediately after testing all measurements, PT stiffness and thickness were set at 5-10-15-20 mm distal from the apex of the patella and 5-10 mm proximal to the tibial tuberosity. CSA was set at proximal, middle, and distal, while echogenicity was at proximal and distal points. The results showed significant increases in PT stiffness at all reference points after start acceleration (p<0.001). PT thickness showed similar results for stiffness, except for location placed at TT-5 (p<0.001). CSA increased significantly in proximal, middle, and distal regions (p<0.001), while echogenicity of the tendon increased in proximal and distal regions (p<0.001) after start acceleration. Regional-dependent alterations of PT thickness and stiffness may be related to anatomical and physiological mechanisms due to acute isometric contraction in the initial phase of standing start. Tendon echogenicity might be also useful in monitoring tendon mechanical properties and defining acute fatigue-induced changes.

Predicting Changes in Maximal Oxygen Uptake in Response to Polarized Training (Sprint Interval Training, High-Intensity Interval Training, and Endurance Training) in Mountain Bike Cyclists.

ABSTRACT: Hebisz, R, Hebisz, P, Danek, N, Michalik, K, and Zaton, M. Predicting changes in maximal oxygen uptake in response to polarized training (sprint interval training, high-intensity interval training, and endurance training) in mountain bike cyclists. J Strength Cond Res 36(6): 1726-1730, 2022-The aim of this study was to determine the predictors of change in maximal oxygen uptake (ΔV̇o2max) in response to a polarized training program. Twenty well-trained mountain bike cyclists completed an 8-week intervention of sprint interval training (SIT) (8-16 30-second maximal sprints), high-intensity interval training (4-6 bouts at 85-95% maximal aerobic power), and endurance training (2-3 hours cycling at 70-80% power at the ventilatory threshold). An incremental exercise test was performed to determine preintervention and postintervention maximal oxygen uptake (V̇o2max) and maximal pulmonary ventilation (VEmax) normalized to lean body mass (LBM). The frequency and time domain of heart rate variability (HRV) was also determined during recovery after moderate warm-up in the first and last SIT. Training status was quantified as the total distance cycled in the previous year. V̇o2max, VEmax, and the root mean square of the successive differences of normal-to-normal time interval between heartbeats (RMSSD), which is the time domain of HRV all increased significantly. Multiple significant correlations were observed between ΔV̇o2max and training status and baseline measures of VEmax·LBM-1, RMSSD, and V̇o2max·LBM-1 and a regression equation was developed (r = 0.87, r2 = 0.76; p = 0.0001). The change in V̇o2max in response to polarized training can be predicted with high accuracy based on several measurable variables.

Foam rolling and tissue flossing of the triceps surae muscle: an acute effect on Achilles tendon stiffness, jump height and sprint performance - a randomized controlled trial.

This study aimed to investigate an acute effect of foam rolling and tissue flossing of the Triceps Surae muscle on Achilles tendon stiffness, jump height and sprint performance at different time points. The participants were academic athletes (n = 32) aged between 22 and 24 years; randomly allocated into two groups: foam rolling (ROLL) and tissue flossing (FLOSS). The participants were tested at baseline and 5-min, 15-min, 30-min, 45-min, and 60-min after ROLL and FLOSS for Achilles tendon stiffness (ATstiffeness) at three reference locations: (1) tendon's origin, (2) ankle joint height and (3) intermuscular septum of the gastronomies muscle; countermovement jump (CMJ); and sprint performance at 15-m (SPRINT15 m). The analysis of stiffness revealed a significant decrease in ATstiffness from baseline to Post-60 (p ≤ 0.001) for three locations in the FLOSS group (p ≤ 0.001). In FLOSS, a significant increase was observed from Post-15 to Post-60 (all p≤0.001) in CMJ. We found also a significant decrease in SPRINT15 m in FLOSS in all-time points (p ≤ 0.001), however, SPRINT15 m decreased in Post-5 min, Post-15 min, and Post-30 min (p ≤ 0.001 for all) in ROLL. The current study suggested that both groups enhanced performance up to 60 min after the intervention, caused by mitigating excessive stiffness.

Effects of Swimming with Added Respiratory Dead Space on Cardiorespiratory Fitness and Lipid Metabolism.

The aim of this study was to investigate the circulatory, respiratory, and metabolic effects of induced hypercapnia via added respiratory dead space (ARDS) during moderate-intensity swimming in recreational swimmers. A mixed-sex sample of 22 individuals was divided into homogeneous experimental (E) and control (C) groups controlled for maximal oxygen uptake (VO2max). The intervention involved 50 min of front crawl swimming performed at 60% VO2max twice weekly for 6 consecutive weeks. ARDS was induced via tube breathing (1000 ml) in group E. An incremental exercise test was administered pre- and post-intervention to assess cardiorespiratory fitness (CRF) by measuring VO2max, carbon dioxide volume, respiratory minute ventilation, respiratory exchange ratio (RER), and heart rate at 50, 100, 150, 200 W and at maximal workload. Body mass index (BMI), fat mass (FM), and fat-free mass (FFM) were also measured. The mean difference in glycerol concentration (ΔGLY) was assessed after the first and last swimming session. No significant between-group differences were observed at post-intervention. No within-group differences were observed at post-intervention except for RER which increased in group E at maximal workload. A 6-week swimming intervention with ARDS did not enhance CRF. The RER increase in group E is not indicative of a substrate shift towards increased lipid utilization. No change in ΔGLY is evident of a lack of enhanced triglyceride hydrolyzation that was also confirmed by similar pre- and post-intervention BMI, FM, and FMM.

Submaximal Verification Test to Exhaustion Confirms Maximal Oxygen Uptake: Roles of Anaerobic Performance and Respiratory Muscle Strength.

Background: The incremental exercise test is commonly used to measure maximal oxygen uptake (VO2max), but an additional verification test is often recommended as the "gold standard" to confirm the true VO2max. Therefore, the aim of this study was to compare the peak oxygen uptake (VO2peak) obtained in the ramp incremental exercise test and that in the verification test performed on different days at submaximal intensity. Additionally, we examined the roles of anaerobic performance and respiratory muscle strength. Methods: Sixteen physically active men participated in the study, with an average age of 22.7 ± 2.4 (years), height of 178.0 ± 7.4 (cm), and weight of 77.4 ± 7.3 (kg). They performed the three following tests on a cycle ergometer: the Wingate Anaerobic Test (WAnT), the ramp incremental exercise test (IETRAMP), and the verification test performed at an intensity of 85% (VER85) maximal power, which was obtained during the IETRAMP. Results: No significant difference was observed in the peak oxygen uptake between the IETRAMP and VER85 (p = 0.51). The coefficient of variation was 3.1% and the Bland-Altman analysis showed a high agreement. We found significant correlations between the total work performed in the IETRAMP, the anaerobic peak power (r = 0.52, p ≤ 0.05), and the total work obtained in the WAnT (r = 0.67, p ≤ 0.01). There were no significant differences in post-exercise changes in the strength of the inspiratory and expiratory muscles after the IETRAMP and the VER85. Conclusions: The submaximal intensity verification test performed on different days provided reliable values that confirmed the real VO2max, which was not limited by respiratory muscle fatigue. This verification test may be suggested for participants with a lower anaerobic mechanical performance.

Sports Diagnostics-Maximizing the Results or Preventing Injuries.

Sports diagnostics is a comprehensive scientific concept and comprises an aspect of training monitoring and/or sports medicine [...].

Comparison of body composition components and anaerobic performance parameters of elite male motorcycle speedway riders between pre- and post-competitive season.

The purpose of this study was to compare body composition components and anaerobic capacity indices in elite motorcycle speedway riders before and after the competitive season. This study included 12 volunteer male motorcycle speedway riders from the highest speedway league in Poland (PGE Speedway Ekstraliga) (age: 22.7 ± 6.0 years, body height: 171.3 ± 4.0 cm, body weight: 62.5 ± 3.1 kg). Before and after the competitive season, an assessment of body composition and Wingate test (WAnT) on a cycle ergometer with analysis of acute cardiorespiratory and biochemical responses was conducted. Sport level for all riders was defined by the number of heats won (WS), the total number of points scored in all heats including bonus points (PTS + B), and the percentage of heats won (%W). The motorcycle speedway riders participated in an average of 75.3 ± 15.0 total heats (HS) and obtained PTS + B equal 136.8 ± 48.2. The anaerobic performance, body composition, cardiorespiratory and biochemical responses did not changed after the competitive season. The significant statistical correlations were noted between the differences in the Fatigue Index during WAnT and total number of heats (r = -0.61) and with PTS + B (r = -0.58). Positively correlations were observed also between HS and differences: fat mass (FM) (r = 0.60) and percentage of fat mass (r = 0.61) (all p < 0.05). These findings reveal that the HS during the competitive season is related to the stabilization of anaerobic capacity in the WAnT. The HS is positively correlated with an increase in fat mass, and additional fat mass can adversely affect athletic performance in speedway.

Determination of optimal load in the Wingate Anaerobic Test is not depend on number of sprints included in mathematical models.

Determining the optimal load (OPTLOAD) in measuring mechanical peak power output (PPO) is important in assessment of anaerobic fitness. The main goals of this study were: 1) to examine estimated optimal load and PPO based on a force-velocity test and 2) to compare the PPO from the previous method with the Wingate Anaerobic Test (WAnT). The study involved 15 academic male athletes, aged 22.4 ± 2.3 (years), height 178.9 ± 6.8 (cm), and body weight 77.9 ± 12.2 (kg). They performed the 30-s WAnT (7.5% of body weight) during the first visit to the laboratory. Second to fourth session included a force-velocity test (FVT) involving three, 10-s all-out sprints. A randomized load ranging from 3 to 11 kg was used in each session for FVT. The OPTLOAD and PPO were computed using quadratic relationships based on power-velocity (P-v) and power-percent of body weight (P-%BM) and including three, four, five and nine sprints from FVT. The results showed non-difference in OPTLOAD [13.8 ± 3.2 (%BM); 14.1 ± 3.5 (%BM); 13.5 ± 2.8 (%BM); 13.4 ± 2.6 (%BM)] executed at three, four, five, and nine sprints (F3,56 = 0.174, p = 0.91, η2 = 0.01). The two-way ANOVA revealed that PPO were similar between tested models (P-%BM vs. P-v) independently from the numbers of sprints (F3,112 = 0.08, p = 0.99, η2 = 0.000). Moreover, the PPO measured in the WAnT (870.6 ± 179.1 W) was significantly lower compared with in P-v model (1,102.9 ± 242.5-1,134.2 ± 285.4 W) (F4,70 = 3.044, p = 0.02, η2 = 0.148). In addition, the PPO derived from P-%BM model (1,105.2 ± 245.5-1,138.7 ± 285.3 W) was significantly higher compared with the WAnT (F4,70 = 2.976, p = 0.02, η2 = 0.145). The findings suggest the potential utility of FVT for assessment of anaerobic capacity.

The importance of reaction time to the starting signal on race results in elite motorcycle speedway racing.

The study aimed to determine whether the reaction time (RT) to the starting signal has an impact on the points scored by elite male motorcycle speedway riders, or whether it depends on the starting position (gate). Differences among junior and senior riders, and how it changes during a single match (15 heats) and in the subsequent phases of the competitive season (the main and knockout phases) were investigated. The database of reaction times to the starting signal obtained by motorcycle speedway riders was collected from a mobile application called PGE Ekstraliga ver. 1.0.66 (PGE Ekstraliga, Warsaw, Poland). The database included 1.261 results obtained by 65 male riders (age 25.9 ±7.6 years), competing in the highest league in Poland (PGE Speedway Ekstraliga) in the 2021 competitive season. Reaction time was measured using the Pegasus Speedway © telemetry system (Black Burst, Warsaw, PL). Riders scoring 3 points during a heat had the fastest reaction time (F(3,1257) = 8.90, p<0.001, η2 = 0.02), but RT did not influence the final result of the match (p<0.130). The times differ depending on the occupied starting position (F(3,1257) = 6.89, p<0.001, η2 = 0.02), with the fastest RT in the inner position-A compared to the B (p<0.05) and C (p <0.001) positions. Senior riders showed significantly faster RT (0.246s) compared to junior ones (0.258s) (p<0.001). The width of the starting line affects the reaction time (F(3,1257) = 7.94, p<0.001, η2 = 0.02). In the last (15th) heat of the match, RT was the fastest. The fast reaction time during the start affects the scoring of more points in a heat but depends on riders' experience, the starting position and the straight width of the motorcycle speedway stadium. Coaches should pay attention to these factors when programming training measures.

Track cycling sprint sex differences using power data.

Objectives: Currently, there are no data on sex differences in the power profiles in sprint track cycling. This cross-section study analyses retrospective data of female and male track sprint cyclists for sex differences. We hypothesized that women would exhibit lower peak power to weight than men, as well as demonstrate a different distribution of power durations related to sprint cycling performance. Design: We used training, testing, and racing data from a publicly available online depository (www.strava.com), for 29 track sprint cyclists (eight women providing 18 datasets, and 21 men providing 54 datasets) to create sex-specific profiles. R2 was used to describe model quality, and regression indices are used to compare watts per kilogram (W/kg) for each duration for both sexes against a 1:1 relationship expected for 15-s:15-s W/kg. Results: We confirmed our sample were sprint cyclists, displaying higher peak and competition power than track endurance cyclists. All power profiles showed a high model quality (R2 ≥ 0.77). Regression indices for both sexes were similar for all durations, suggesting similar peak power and similar relationship between peak power and endurance level for both men and women (rejecting our hypothesis). The value of R2 for the female sprinters showed greater variation suggesting greater differences within female sprint cyclists. Conclusion: The main finding shows female sprint cyclists in this study have very similar relationships between peak power and endurance power as men. Higher variation in W/kg for women in this study than men, within these strong relationships, indicates women in this study, had greater inter-athlete variability, and may thus require more personalised training. Future work needs to be performed with larger samples, and at different levels to optimize these recommendations.

Changes in Reaction Time, Balance and Neuroplasticity after Exercise with a Face Mask in Male Adults with Mild COVID-19 Symptoms.

This study compared physiological, perceptual and neuroprotective hormone and metabolite responses and changes in coordination as an effect of aerobic exercise with and without a face mask in people with mild symptoms of COVID-19. Forty men took part in this study. Half declared mild symptoms of SARS-CoV-2 infection in the 6 months before the study (Declared) and the other half did not (Non-declared). In a random order, with a 7-day interval, they performed a 30-min walk on a treadmill at a speed of 6 km/h wearing a surgical face mask (Masked) and without it (Unmasked). The heart rate, heart rate variability, oxygen saturation, lactate concentration and rate of perceived exertion were recorded. The reaction time and balance were measured before and after the exercise. The concentrations of brain-derived neurotrophic factor, testosterone, cortisol, epinephrine and antibodies in the blood serum were determined. Physiological and perceptual responses, reaction times, and balance did not differ between the tested conditions. Three-way RM-ANOVA with post hoc Bonferroni analysis revealed lower post-exercise cortisol concentrations in the Masked and Unmasked conditions in both groups (p ≤ 0.001). Asymptomatic infection with this virus is prevalent, and mild COVID-19 causes similar responses to aerobic exercise with a surgical face mask and does not lead to impaired coordination.

Power-duration relationship comparison in competition sprint cyclists from 1-s to 20-min. Sprint performance is more than just peak power.

Current convention place peak power as the main determinant of sprint cycling performance. This study challenges that notion and compares two common durations of sprint cycling performance with not only peak power, but power out to 20-min. There is also a belief where maximal efforts of longer durations will be detrimental to sprint cycling performance. 56 data sets from 27 cyclists (21 male, 6 female) provided maximal power for durations from 1-s to 20-min. Peak power values are compared to assess the strength of correlation (R2), and any relationship (slope) across every level. R2 between 15-s- 30-s power and durations from 1-s to 20-min remained high (R2 ≥ 0.83). Despite current assumptions around 1-s power, our data shows this relationship is stronger around competition durations, and 1-s power also still shared strong relationships with longer durations out to 20-min. Slopes for relationships at shorter durations were closer to a 1:1 relationship than longer durations, but closer to long-duration slopes than to a 1:1 line. The present analyses contradicts both well-accepted hypotheses that peak power is the main driver of sprint cycling performance and that maximal efforts of longer durations out to 20-min will hinder sprint cycling. This study shows the importance and potential of training durations from 1-s to 20-min over a preparation period to improve competition sprint cycling performance.

Reliability of a semi-tethered front crawl sprint performance test in adolescent swimmers.

This study aimed to evaluate the test-retest reliability of a sprint performance test with semi-tethered front crawl swimming to indirectly assess the current potential to perform at maximal anaerobic effort in adolescent swimmers. Eight adolescent swimmers participated in this study (gender: females (n = 4) aged 13.0 ± 0.8 years, body height 1.6 ± 0.0 m, body mass 50.1 ± 4.5 kg; and males (n = 4) aged 13.3 ± 1.3 years, body height 1.7 ± 0.1 m, body mass 59.0 ± 8.2 kg. The testing protocol consisted of two trials of 25 m semi-tethered front crawl swimming with maximal effort and with 1 kg resisted isotonic load. Velocity data were recorded automatically by the 1080 Sprint device for 15 m (between 3 m and 18 m). The Fast Fourier Transform algorithm filtered raw instantaneous swimming velocity data in distance (time) function. A third-degree polynomial was used to extract the individual velocity profile, from which the following variables were chosen for test-retest reliability and the assessment of sprint performance: ttrial15, vmax, vmin, tvto max, tvat max, Dto vmax, Dat vmax, fatigue index. Parameters such as vmax, vmin, and ttrial15 were estimated from swimming velocity profiles and considered as reliable. The CV showed low variance <5%; while ICC2,1 demonstrated respectively good (ICC2,1: 0.88), very good (ICC2,1: 0.95), and excellent (ICC2,1: 0.98) rate of relative reliability; and the Bland-Altman index revealed an acceptable agreement (LoA ≤5%) between two measurements. The sprint performance test based on semi-tethered front crawl swimming confirmed that ttrial15, vmax, and vmin were reliable variables to indirectly indicate a potential to perform the maximal anaerobic effort among adolescent swimmers. The evaluation of the swimming velocity profiles allows coaches to monitor the adaptive changes of performance during the training process.

Warm-Up With Added Respiratory Dead Space Volume Mask Improves the Performance of the Cycling Sprint Interval Exercise: Cross-Over Study.

Special breathing exercises performed during warm-up lead to hypercapnia and stimulation of mechanisms leading to increased exercise performance, but the effect of a device that increases the respiratory dead space volume (ARDSv) during warm-up has not been studied. The purpose of this study was to investigate the effect of 10 min warm-up with ARDSv on performance, physiological and biochemical responses during sprint interval cycling exercise (SIE). During four laboratory visits at least 72 h apart, they completed: (1) an incremental exercise test (IET) on a cycloergometer, (2) a familiarization session, and cross-over SIE sessions conducted in random order on visits (3) and (4). During one of them, 1200 mL of ARDSv was used for breathing over a 10-min warm-up. SIE consisted of 6 × 10-s all-out bouts with 4-min active recovery. Work capacity, cardiopulmonary parameters, body temperature, respiratory muscle strength, blood acid-base balance, lactate concentration, and rating of perceived exertion (RPE) were analyzed. After warm-up with ARDSv, P ET CO2 was 45.0 ± 3.7 vs. 41.6 ± 2.5 (mm Hg) (p < 0.001). Body temperature was 0.6 (°C) higher after this form of warm-up (p < 0.05), bicarbonate concentration increased by 1.8 (mmol⋅L-1) (p < 0.01). As a result, work performed was 2.9% greater (p < 0.01) compared to the control condition. Respiratory muscle strength did not decreased. Warming up with added respiratory dead space volume mask prior to cycling SIE produces an ergogenic effect by increasing body temperature and buffering capacity.

The Relationship Among Body Composition and Anaerobic Capacity and the Sport Level of Elite Male Motorcycle Speedway Riders.

The main objective of this study was to investigate the relationship among anaerobic capacity, body composition, and sport level of male junior and senior speedway riders. Sixty riders of professional clubs in the Polish top motorcycle speedway league participated in this study. They were divided into two equal groups (n = 30): junior (age = 19.7 ± 1.1 years) and senior (age = 29.7 ± 5.2). Body composition assessment, Wingate test (WAnT) on cycloergometer, with analysis of acute cardiorespiratory and biochemical responses were performed. Sport level was defined as the number of heats (races) won, winning percentage, total points scored during the season, and average points scored per heat. Seniors had higher point ratings indicating sport levels. As compared to the seniors, the juniors had lower BMI 4% (p < 0.01) and fat tissue mass by 20.5% (p < 0.01). A higher power decrease of 2.3% (p < 0.05) in the WAnT test was found in seniors. Body height negatively correlated with all indicators of seniors' sport level (r = -0.41 to -0.55). Peak power output negatively correlated with seniors' sport level (r = -0.39 to -0.41). Among the seniors, there was a negative correlation between post-exercise hydrogen ion concentration (r = -0.38), carbon dioxide partial pressure (r = -0.45) and average points scored per season. Conclusion: The anthropometric characteristics of body height, lean body mass and body surface area, are significantly correlated with the sport levels of the seniors motorcycle speedway riders. When selecting motorcycle speedway riders, use of these anthropometric characteristics may aid in determining the riders with the most potential to be successful. Metabolic acidosis tolerance and gas exchange efficiency show significance in seniors, indicating the need for intense exercise sessions.

Comparison of the Ramp and Step Incremental Exercise Test Protocols in Assessing the Maximal Fat Oxidation Rate in Youth Cyclists.

The incremental exercise test is the most common method in assessing the maximal fat oxidation (MFO) rate. The main aim of the study was to determine whether the progressive linear RAMP test can be used to assess the maximal fat oxidation rate along with the intensities that trigger its maximal (FATmax) and its minimal (FATmin) values. Our study comprised 57 young road cyclists who were tested in random order. Each of them was submitted to two incremental exercise tests on an electro-magnetically braked cycle-ergometer - STEP (50 W·3 min-1) and RAMP (~0.278 W·s-1) at a 7-day interval. A stoichiometric equation was used to calculate the fat oxidation rate, while the metabolic thresholds were defined by analyzing ventilation gases. The Student's T-test, Bland-Altman plots and Pearson's linear correlations were resorted to in the process of statistical analysis. No statistically significant MFO variances occurred between the tests (p = 0.12) and its rate amounted to 0.57 ± 0.15 g·min-1 and 0.53 ± 0.17 g·min-1 in the STEP and RAMP, respectively. No statistically significant variances in the absolute and relative (to maximal) values of oxygen uptake and heart rate were discerned at the FATmax and FATmin intensities. The RAMP test displayed very strong oxygen uptake correlations between the aerobic threshold and FATmax (r = 0.93, R2 = 0.87, p < 0.001) as well as the anaerobic threshold and FATmin (r = 0.88, R2 = 0.78, p < 0.001). Our results corroborate our hypothesis that the incremental RAMP test as well as the STEP test are reliable tools in assessing MFO, FATmax and FATmin intensities.

Comparison of Acute Responses to Two Different Cycling Sprint Interval Exercise Protocols with Different Recovery Durations.

Background: Knowledge of acute responses to different sprint interval exercise (SIE) helps to implement new training programs. The aim of this study was to compare the acute physiological, metabolic and perceptual responses to two different SIE cycling protocols with different recovery durations. Methods: Twelve healthy, active male participants took part in this study and completed four testing sessions in the laboratory separated by a minimum of 72h. Two SIE protocols were applied in randomized order: SIE6×10"/4'-six "all-out" repeated 10-s bouts, interspersed with 4-min recovery; and SIESERIES-two series of three "all-out" repeated 10-s bouts, separated by 30-s recovery and 18-min recovery between series. Protocols were matched for the total work time (1 min) and recovery (20 min). Results: In SIESERIES, peak oxygen uptake and peak heart rate were significantly higher (p < 0.05), without differences in peak blood lactate concentration and mean rating of perceived exertion compared to SIE6×10"/4'. There were no differences in peak power output, peak oxygen uptake and peak heart rate between both series in SIESERIES. Conclusions: Two series composed of three 10-s "all-out" bouts in SIESERIES protocol evoked higher cardiorespiratory responses, which can provide higher stimulus to improve aerobic fitness in regular training.

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.

Influence of a Six-Week Swimming Training with Added Respiratory Dead Space on Respiratory Muscle Strength and Pulmonary Function in Recreational Swimmers.

The avoidance of respiratory muscle fatigue and its repercussions may play an important role in swimmers' health and physical performance. Thus, the aim of this study was to investigate whether a six-week moderate-intensity swimming intervention with added respiratory dead space (ARDS) resulted in any differences in respiratory muscle variables and pulmonary function in recreational swimmers. A sample of 22 individuals (recreational swimmers) were divided into an experimental (E) and a control (C) group, observed for maximal oxygen uptake (VO2max). The intervention involved 50 min of front crawl swimming performed at 60% VO2max twice weekly for six weeks. Added respiratory dead space was induced via tube breathing (1000 mL) in group E during each intervention session. Respiratory muscle strength variables and pulmonary and respiratory variables were measured before and after the intervention. The training did not increase the inspiratory or expiratory muscle strength or improve spirometric parameters in any group. Only in group E, maximal tidal volume increased by 6.3% (p = 0.01). The ARDS volume of 1000 mL with the diameter of 2.5 cm applied in moderate-intensity swimming training constituted too weak a stimulus to develop respiratory muscles and lung function measured in the spirometry test.