Effect of four weeks of repeated sprint training with blood flow restriction on upper limb microcirculation in boxers

This study evaluates the impact of 4 weeks of 40% arterial occlusion pressure (AOP) blood flow restriction (BFR) combined with repeated sprint training (RST) on the microcirculation function of upper limbs in boxers and investigates the potential mechanisms underlying improvements in microcirculation from the perspective of blood factor changes. Thirty-six healthy male collegiate boxers were assigned to either a blood flow restriction training group (Experimental Group, EG, n = 18) or a conventional training group (Control Group, CG, n = 18), completing 12 sessions over 4 weeks (three sessions per week). The training regimen for EG and CG was identical, except EG underwent BFR during the training sessions. Measurements of arm circumference, muscle strength, microcirculation function (4 indicators), and blood factor (4 indicators) were taken one day before training began and the day after the final training session. Using two-factor repeated measures ANOVA, significant differences were observed in EG's arm circumference at tension, muscle strength, microvascular blood flow perfusion, transcutaneous oxygen pressure, muscle oxygen saturation, nitric oxide levels, endothelial nitric oxide synthase, endothelin-1, and vascular endothelial growth factor, all showing improvements from baseline. In contrast, CG only demonstrated increased upper limb strength, with no significant changes in the other indicators. These findings suggest that while both training protocols may enhance muscle strength, the addition of BFR notably improves upper limb microcirculation and muscle strength in collegiate boxers by modulating the secretion of blood factors such as endothelial nitric oxide synthase, endothelin-1, and vascular endothelial growth factor.

Physical Capacities and Combat Performance Characteristics of Male and Female Olympic Boxers

Purpose: The study characterized the anthropometrical and cardiorespiratory profile, and the cardiorespiratory, bio-chemical and immunological responses to 3 × 3 min round (R) free-contact/combat boxing simulation, in elite Olympic Boxers (4 female and 10 male). Methods: The evaluation consisted of resting metabolic rate, anthropometric measurement, maximal graded test exercise (visit 1), free combat simulation (3 × 3 min R, 1 minute rest), and blood samples collected before, during and after the combat (visit 2). Results: Respectively, females and males had (mean±SD; or median: for non-parametric data) body fat percentage (17.2[3.5] and 4.6[0.8]%), predominantly mesomorphic somatotyping, and V ˙ O 2 MAX (50.0 ± 2.5 and 56.2 ± 5.2 ml.kg-1.min-1). The free combat simulation resulted in high cardiovascular strain [mean heart rate corresponding to R1: 92 ± 3; R2: 94 ± 2; and R3: 95 ± 2% of maximal HR] and blood chemistry indicative of acidosis (following R3: 7.21 ± 0.08 pH, bicarbonate 13.1 ± 3.6 mmol.L-1, carbon dioxide 13.9 ± 3.8 mmol.L-1, lactate 15.1 ± 3.8 mmol.L-1, and glucose 8.4 ± 1.3 mmol.L-1). Further, notable general catabolism, hematological and immune responses were evident post combat simulation (1-hour post R3: creatinine 95.2 ± 14.5 µmol.L-1, urea 6.4 ± 1.3 mmol.L-1, white blood cell accumulation 7.8 ± 2.6 × 109.L-1, hemoglobin 14.9 ± 0.8 g.dL-1 and hematocrit 43.7 ± 1.9%). Conclusions: Notable cardiovascular strain and acidosis are seen from the 3 × 3 free combat simulation whilst pronounced catabolism and immune responses are evident 1-hour post R3. This characterization is the first in male and female (who recently adopted the 3 × 3 min R format, as used by males) elite Olympic boxers and provides a characterization framework to assist practitioners and athletes in their attempts to deliver evidence-informed practice for specific conditioning session design.

Impact of three weeks of integrative neuromuscular training on the athletic performance of elite female boxers

Objectives

To investigate the effects of integrative neuromuscular training (INT) on the athletic performance of elite female boxers.

Methods

A before-and-after controlled experiment was conducted on 37 elite Chinese female boxers (Age: 26.00 ± 3.11 years). All included athletes have competed at the international level. The INT intervention was administered 11 times per week for 3 weeks. This training includes strength training, explosive training, core stability, agility exercises, high intensity intervals and sprint intervals. Basic physical fitness tests, including the deep squat and bench press one-repetition maximum (1RM), vertical long jump, 30 m sprint run, 400 m run, 3,000 m run, 1-minute hexagonal jump, and 3-minute double shake; as well as specialized striking ability tests, including single-punch striking and 10-second, 30-second, and 3-minute continuous punching, were conducted before and after the intervention.

Results

Compared with pre-intervention baseline data, significant differences were found in the athletes' post-intervention baseline physical fitness, including squat and beach press (1RM), vertical jump, 30 m sprint run, 400 m run, 3,000 m run, 1-minute hexagonal jump, and 3-minute double shake (p < 0.05). Additionally, 10-second, 30-second, and 3-minute continuous punching were significantly different compared with pre-intervention (p < 0.05). However, no significant differences were found in single punch power (p > 0.05).

Conclusion

The 3-week INT can significantly improve the maximum strength, vertical explosive power, linear acceleration, agility, and continuous punching abilities of Chinese elite female boxers. The use of INT in physical training may enhance their athletic performance.

Impact of Leg Strength on the Force Produced During a Cross-Punch in Highly Trained Amateur Boxers

ABSTRACT

Satkunskiene, D, Bruzas, V, Mantas, M, Snieckus, A, and Kamandulis, S. Impact of leg strength on the force produced during a cross-punch in highly trained amateur boxers leg strength impact on cross-punch force. J Strength Cond Res 38(10): 1739-1744, 2024-The purpose of this study was to determine the impact of leg strength on force generation during the execution of a cross-punch by highly trained amateur boxers. This study involved 12 male, amateur boxers with a body mass range of 64.5-112.2 kg and a mean of 89.2 ± 17.0 kg. This study used an isokinetic dynamometer to measure the peak torque of the knee extensor and flexor muscles at 60°/s. The force plate was used to collect three-dimensional ground reaction forces (GRF), moments (GRM), and the center of pressure (COP) during a maximal cross-punch. The Kiktest-100 system was used to determine the force of the punch, while the Hykso punch tracker accelerometer measured the maximum fist velocity. This study revealed a positive correlation between knee extensor strength and GRFz, GRFy, and COPy during punch performance. In addition, the GRMz gradient and GRMz impulse during the execution phase have a significant positive effect on cross-punch force. In conclusion, the force of a straight punch in highly trained, amateur boxers is related to a greater angular velocity about the vertical axis during body rotation.

Impact of Anaerobic Exercise Integrated Into Regular Training on Experienced Judo Athletes: Running Vs. Repetitive Throws

ABSTRACT

Kamandulis, S, Dudėnienė, L, Snieckus, A, Kniubaite, A, Mickevicius, M, Lukonaitiene, I, Venckunas, T, Stasiule, L, and Stasiulis, A. Impact of anaerobic exercise integrated into regular training on experienced judo athletes: running vs. repetitive throws. J Strength Cond Res 38(9): e489-e495, 2024-Anaerobic training in high-level athletes is of considerable interest to practitioners aiming to optimize performance. This study compared the impact of interval anaerobic training (IAT) sessions consisting of either high-intensity running or throwing that were performed twice a week together with regular judo training on the anaerobic and aerobic performance of experienced judo athletes. Employing a repeated-measures, counterbalancing, research design, 12 national team judo athletes (7 women and 5 men; mean age, 20.4 ± 0.95 years; mean judo training experience, 13.4 ± 1.4 years; competitive level, black belt first and second Dan) performed each IAT modality for 6 weeks, for a full training cycle of 12 weeks. Assessments of their anaerobic fitness (Cunningham and Faulkner Anaerobic Treadmill Test), sport-specific anaerobic fitness (Special Judo Fitness Test [SJFT]), and aerobic capacity (maximal incremental treadmill running test) were performed before, after 6 weeks, and after 12 weeks of training. The uphill running performance improved by 13.1% over the 12-week period ( p = 0.047). Simultaneously, there was a 9.0% improvement in the SJFT index and a 6.9% increase in the number of throws ( p = 0.011 and p = 0.017, respectively). Although a trend for throwing drills being more effective than interval sprint running was observed, the interaction effect lacked statistical significance ( p = 0.074). Moreover, no substantial changes were noted in aerobic endurance markers. In conclusion, this study suggests that incorporating specific and nonspecific high-intensity drills into a routine training regimen may enhance anaerobic capacity among well-trained judo athletes, potentially leading to favorable competitive outcomes.

Anaerobic Performance Profiling in Elite Amateur Boxers

While anaerobic fitness is highly important for the performance in Olympic (amateur) boxing, the relationship between anaerobic performance metrics is poorly understood, and profiling boxers according to their anaerobic capacity is still a challenge. With the current study in elite amateur boxers, we aimed to compare the metabolic and cardiovascular responses to different maximal tests and the intercorrelations between performance indices (peak and mean power, duration of the test, punching frequency) of several all-out tests and their correlation to physiological response metrics (blood lactate and heart rate, HR). Twelve male Olympic boxers performed a battery of tests, including 30 s Wingate cycling and arm cranking, boxing bag punching, steep uphill treadmill running to exhaustion, and progressive treadmill running VO2max test. Performance indices of different anaerobic tests were not closely correlated except for the duration of uphill running with body weight scaled (relative) peak and mean power produced during Wingate cycling test and absolute mean power of both Wingate tests. The number of punches landed on a bag per 30 s was associated only with relative power achieved during Wingate cycling test. HRpeak but not peak lactate response correlated strongly across exercise tasks. Finally, no correlation between the highly developed aerobic and anaerobic capacity, suggests a complex picture of the adaptation in elite amateur boxers.

A physical fitness-evaluation system for outstanding Chinese male boxers

Background

We sought to create a system to evaluate the physical fitness of outstanding Chinese male boxers that included an evaluation index, fitness level criteria, and modeling. This system was then used to assess athletes' physical fitness and development.

Methods

Documentation, expert interviews, questionnaires, measurements, and statistical analyses were used in this study.

Results

The physical fitness evaluation system included the following three components: (1) body shape indexes (n = 4) including the backhand upper arm circumference differential, finger span height, Cottrell index, and pelvic width/shoulder width × 100; (2) body function indexes (n = 4) including relative maximum anaerobic power, relative maximal oxygen uptake, and creatine kinase and testosterone concentrations; and (3) athletic quality indexes (n = 9) including the speed strength index, the backhand straight punch strength, 3-min cumulative punching force, backhand straight punch reaction time, backhand straight punch speed, 30-m sprint, 9-min double shake jump rope, 1-min double shake jump rope, and sitting forward bend tests. A five-point grading system to evaluate physical fitness was established and an evaluation model was proposed.

Conclusions

The reference values were determined to be objective and effective using a back substitution process. Individual and differential assessments reflected the athletes' level of physical fitness. The critical values were established under the best and worst conditions and the optimal values were found to be valid and effective.

Repeated High-Intensity Technique Training and Repeated Sprint Training Elicit Similar Adjustment in Physiological Responses But Divergent Perceptual Responses and Combat-Related Performances in Adolescent Taekwondo Matches

PURPOSE

This study investigated the effects of 4 weeks of repeated sprint training (RST) versus repeated high-intensity technique training (RTT) on the physiological responses (ie, blood lactate), mean and peak heart rate, rating of perceived exertion, technical-tactical performance, and time-motion variables during simulated taekwondo combats.

METHODS

Twenty-four taekwondo athletes (18 male and 6 female; age: 16 [1] y) were randomly and equally assigned to RST (10 × 35-m running sprints interspersed by 10-s rest) or RTT (10 × 6-s bandal-tchagui kicking executions interspersed by 10-s rest) groups in addition to their regular training. Both groups performed simulated combats before and after training.

RESULTS

Delta lactate and peak heart rate were attenuated following training (P < .001 and P = .03, respectively), with no differences identified between RTT and RST conditions. Rating of perceived exertion decreased after training only in the RTT (P = .002). Time fighting and preparatory activities increased following training (P < .001), with higher values observed following RTT than RST (P < .001). Nonpreparatory time decreased after training (P < .001), with more pronounced reductions observed following RTT when compared to RST (P < .001). The number of single attacks decreased only following RST (P < .001), whereas combined attacks increased only after RTT training (P < .001).

CONCLUSIONS

Similar adjustments in the physiological responses to combat were observed following 4 weeks of either RST or RTT, but RTT elicited more favorable perceptual responses and combat-related performance. This highlights the importance of specificity of training and its effective transfer to combat.

Reliability and Practical Use of a Commercial Device for Measuring Punch and Kick Impact Kinetics

Martial arts, boxing and combat sports such as mixed martial arts participation have gained popularity in recent years internationally. One common aspect to these sports is the training and skill in maximizing strike impact of punches and kicks, referred to as impact kinetics, with commercial devices now available to assess punching and kicking power in athletes training facilities and gyms. We, therefore, assessed the reliability of a commercial device, the PowerKubeTM (Strike Research Ltd., Norwich, England) via the technical error of measurement (TEM) in both linear and non-linear simulated strikes to the center of target, off-center, level and inclined in a laboratory setting. The highest mean impact power resulted from level, center strikes (5782 ± 230 W) followed by level, off-center strikes (4864 ± 119 W, p < 0.05), inclined center strikes (4500 ± 220 W, p < 0.05), and inclined, off-center strikes (3390 ± 151). Peak power reductions ranged from 15.9% (level, off-center) to a maximum of 41.4% (incline, off-center) compared to the level, center strikes. Coaches are advised to take steps such as videoing strikes with high sampling rates to better ensure consistency in impact orientation, being perpendicular and centered on the strike pad, to best capture the peak power of kicks or punches.

Effect of a Six Week In-Season Training Program on Wrestling-Specific Competitive Performance

The effect of multi-component training on specific performance is under-researched in wrestlers. The aim of this study was to determine the effect of six weeks of multi-component training on The Special Wrestling Fitness Test (SWFT) performances of wrestlers who were preparing for an international championship, and to, additionally, determine their inter-individual adaptive variability. The wrestlers (n = 13; 7 females; all international level) underwent technical-tactical and physical fitness training for the six weeks before the championship, 12 sessions per week (i.e., 36 h per week). Before and after the intervention the athletes were assessed with the SWFT, a wrestling-specific competitive performance test that includes measurements for throws, heart rate response to the SWFT, and the SWFT index. Significant pre–post intervention improvements were noted for throws (pre = 23.5 ± 2.9; post = 24.9 ± 3.6; p = 0.022) and SWFT_index (pre = 14.9 ± 2.2; post = 14.1 ± 2.2; p = 0.013. In conclusion, six weeks of multi-component training improved wrestling-specific competitive performances in highly-trained wrestlers, although with a meaningful inter-subject variability.

Effects of short sprint interval training on aerobic and anaerobic indices: A systematic review and meta-analysis

The effects of short sprint interval training (sSIT) with efforts of ≤10 seconds on maximal oxygen consumption (V̇O₂ max), aerobic and anaerobic performances remain unknown. To verify the effectiveness of sSIT in physically active adults and athletes, a systematic literature search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The databases PubMed/MEDLINE, ISI Web of Science, SPORTDiscus were systematically searched on the 9^th of May 2020 and updated on the 14^th of September 2021. Inclusion criteria were based on PICO and included healthy athletes and active adults of any sex (≤40 years), performing supervised sSIT (≤10 s of "all out" and non "all out" efforts) of at least 2 weeks, with a minimum of 6 sessions. As a comparator, a non-sSIT control group, another high-intensity interval training (HIIT) group, or a continuous training (CT) group were required. A total of 18 studies was deemed eligible. The estimated SMDs based on the random-effects model were -0.56 (95% CI: -0.79, -0.33, p < 0.001) for V̇O₂ max, -0.43 (95% CI: -0.67, -0.20, p < 0.001) for aerobic performance, and -0.44 (95% CI: -0.70, -0.18, p < 0.001) for anaerobic performance after sSIT vs. no exercise/usual training. However, there were no significant differences (p > 0.05) for all outcomes when comparing sSIT vs. HIIT/CT. Our findings indicate a very high effectiveness of sSIT protocols in different exercise modes (e.g. cycling, running, paddling, punching) to improve V̇O₂ max, aerobic and anaerobic performances in physically active young healthy adults and athletes.

Effects of High-Intensity Interval Training With Specific Techniques on Jumping Ability and Change of Direction Speed in Karate Athletes: An Inter-individual Analysis

This study investigated the effect of 4weeks of high-intensity interval training (HIIT) with specific techniques and analyzed inter-individual variability [classified in responders (Rs) and non-responders (NRs)] on jumping ability and change of direction speed (CODS) in youth karate athletes. Athletes of both genders (n=10) were randomly assigned into experimental group (EG; n=5) and the control group (CG; n=5). The EG trained 2-3days per week applying HIIT (three rounds [15 sets of 4s all-out specific efforts with 8s of dynamical pauses] with 3min of recovery between rounds) during their usual training during 4weeks. Assessments included squat jump (SJ) and countermovement jump (CMJ) and CODS by T-test. No significant interaction effect group by time was found. Although, in percentage and effect size (ES) terms increases were reported in both groups for SJ (EG: 15.2%, ES=0.91 vs. CG: 12.4%, ES=0.02) and only in EG for the T-test (-1.7%; ES=-0.35). In turn, a trend toward a higher proportion of Rs was observed in the EG (40% Rs) vs. CG (20% Rs) for SJ and CODS, respectively. In conclusion, the addition to regular training of a HIIT with specific techniques and based on the temporal combat structure after 4weeks was not a sufficient stimulus to increase jumping ability and CODS in karate athletes.

Effect of a Short HIIT Program with Specific Techniques on Physical Condition and Activity during Simulated Combat in National-Level Boxers

The present study investigated the effect of an additional short-duration HIIT program using boxing-specific techniques on activity during a simulated competition. Additionally, we investigated the impact on physical fitness, specifically aerobic performance and lower-body muscle power. Sixteen boxers were randomized into a control (n = 8) or experimental groups (n = 8). The experimental protocol consisted of 3 blocks of 5 repetitions of 30s all-out effort, with 6s recovery between repetitions and 1 min rest interval between blocks, conducted 3 days per week for 4 weeks. A two-way (group, two levels; moment, two levels) analysis of variance with repeated measurements in the second factor was used. For the experimental group, there was a change in body mass (ES = −0.13 (trivial)), body fat percentage (ES = −0.12 (trivial)), VO2max (ES = +0.42 (small)), CMJ (ES = +0.12 (trivial)), CMJ-left (ES = −0.11 (trivial)), CMJ-right (ES = +0.22 (trivial)), actions (ES = +0.68 (moderate)), time (ES = −0.29 (small)) and punches (ES = +0.56 (moderate)). For the control group, there was a change in body mass (ES = +0.04 (trivial)), body fat percentage (ES = −0.12 (trivial)), VO2max (ES = +0.11 (trivial)), CMJ (ES = −0.27 (small)), CMJ-left (ES = −0.39 (small)), CMJ-right (ES = +0.08 (trivial)), actions (ES = +0.08 (trivial)), time (ES = −0.65 (moderate)) and punches (ES = −0.57 (moderate)). The punches variable was significant concerning group-by-time interaction (F1,14 = 11.630; p = 0.004; n2 = 0.454). The present study indicated that the addition of a boxing-specific HIIT program is effective to increase the number of punches during a simulated match.

Effects of 4 Weeks of a Technique-Specific Protocol with High-Intensity Intervals on General and Specific Physical Fitness in Taekwondo Athletes: An Inter-Individual Analysis

The aim of this research was to compare the effects of a technique-specific high-intensity interval training (HIIT) protocol vs. traditional taekwondo training on physical fitness and body composition in taekwondo athletes, as well as to analyse the inter-individual response. Utilising a parallel controlled design, sixteen male and female athletes (five females and 11 males) were randomly divided into an experimental group (EG) that participated in the technique-specific HIIT and a control group (CG) that participated in traditional taekwondo training. Both groups trained three days/week for four weeks. Squat jump (SJ), countermovement jump (CMJ), 5-metre sprint (5M), 20-metre shuttle run (20MSR), taekwondo specific agility test (TSAT), multiple frequency speed of kick test (FSKT_MULT), total kicks, and kick decrement index (KDI), as well as body composition were evaluated. Results indicate that there are no significant differences (p > 0.05) in the factors group and time factor and group by time interaction (p > 0.05). Although percentage and effect size increases were documented for post-intervention fitness components in TSAT, total kicks, KDI, and 20MSR, responders and non-responders were also documented. In conclusion, a HIIT protocol based on taekwondo-specific technical movements does not report significant differences in fitness and body composition compared to traditional taekwondo training, nor inter-individual differences between athletes.

High-Intensity Interval Training Prescription for Combat-Sport Athletes

CONTEXT

Combat sports are composed of high-intensity actions (eg, attacks, defensive actions, and counterattacks in both grappling and striking situations depending on the specific sport) interspersed with low-intensity actions (eg, displacement without contact, stepping) or pauses (eg, referee stoppages), characterizing an intermittent activity. Therefore, high-intensity interval training (HIIT) is at the essence of combat-sport-specific training and is used as complementary training, as well. HIIT prescription can be improved by using intensity parameters derived from combat-sport-specific tests. Specifically, the assessment of physiological indexes (intensity associated with the maximal blood lactate steady state, maximal oxygen consumption, and maximal sprint) or of time-motion variables (high-intensity actions, low-intensity actions, and effort:pause ratio) is a key element for a better HIIT prescription because these parameters provide an individualization of the training loads imposed on these athletes.

PURPOSE

To present a proposal for HIIT prescription for combat-sport athletes, exemplifying with different HIIT protocols (HIIT short intervals, HIIT long intervals, repeated-sprint training, and sprint interval training) using combat-sport-specific actions and the parameters for the individualization of these protocols.

CONCLUSIONS

The use of combat-sport-specific tests is likely to improve HIIT prescription, allowing coaches and strength and conditioning professionals to elaborate HIIT short intervals, HIIT long intervals, repeated-sprint training, and sprint interval training protocols using combat-sport actions, providing more specificity and individualization for the training sessions.

Repeated Sprint Training vs. Repeated High-Intensity Technique Training in Adolescent Taekwondo Athletes-A Randomized Controlled Trial

This study investigated the effects of 4-weeks repeated sprint (RST) vs. repeated high-intensity-technique training (RTT) on physical performance. Thirty-six adolescent taekwondo athletes (age: 16 ± 1 yrs) were randomly assigned to RST (10 × 35 m sprint, 10 s rest), RTT (10 × 6 s Bandal-tchagui, 10 s rest) and control (control group (CG): no additional training) groups. Additionally, to their regular training, RST and RTT trained 2×/week for 4 weeks. Training load (TL), monotony, and strain were calculated using the rating of perceived exertion scale. The progressive specific taekwondo (PSTT), 20 m multistage shuttle run (SRT_20m), 5 m shuttle run, agility T-test, taekwondo-specific agility (TSAT) and countermovement jump (CMJ) tests were performed before and after 4 weeks of training. Additionally, taekwondo athletes performed specific taekwondo exercises (i.e., repeated techniques for 10 s and 1 min). From week 1, mean TL increased continuously to week 4 and monotony and strain were higher at weeks 3 and 4 (p < 0.001). VO_2max calculated from SRT_20m and PSTT increased for RST and RTT in comparison to CG (p < 0.001). Agility performance during T-test and TSAT (p < 0.01) improved in RTT. The number of performed techniques during the 10 s specific exercise increased in RTT and RST (p < 0.01) for the dominant leg and in RTT for the non-dominant leg (p < 0.01). The number of techniques during the 1 min specific exercise was higher in RST and RTT compared to CG for the dominant leg (p < 0.001). Delta lactate at post-training was lower for RTT for both legs compared to RST and CG (p < 0.01). It is important to include a low-volume high-intensity training based on repeated sprint running or repeated technique in the training programs of adolescent taekwondo athletes.

Acute effects of very low-volume high-intensity interval training on muscular fatigue and serum testosterone level vary according to age and training status

PURPOSE

To compare the acute physiological responses of three different very low-volume cycling sessions (6 × 5 s, 3 × 30 s, and 3 × 60 s) and their dependence on age and training status.

METHODS

Subjects were untrained young men (mean ± SD; age 22.3 ± 4.6 years, VO₂peak 42.4 ± 5.5 ml/kg/min, n = 10), older untrained men (69.9 ± 6.3 years, 26.5 ± 7.6 ml/kg/min, n = 11), and endurance-trained cyclists (26.4 ± 9.4 years, 55.4 ± 6.6 ml/kg/min, n = 10). Maximal voluntary contraction (MVC) and electrically stimulated knee extension torque, and low-frequency fatigue, as ratio of stimulation torques at 20-100 Hz (P20/100), were measured only 24 h after exercise. Serum testosterone (Te) and blood lactate concentrations were measured only 1 h after exercise.

RESULTS

All protocols increased the blood lactate concentration and decreased MVC and P20/100 in young men, but especially young untrained men. In old untrained men, 6 × 5 s decreased P20/100 but not MVC. Te increased after 3 × 30 s and 3 × 60 s in young untrained men and after 3 × 60 s in older untrained men. The increase in Te correlated with responses of blood lactate concentration, MVC, and P20/100 only in old untrained men.

CONCLUSIONS

As little as 6 × 5 s all-out cycling induced fatigue in young and old untrained and endurance-trained cyclists. Slightly higher-volume sessions with longer intervals, however, suppressed contractile function more markedly and also transiently increased serum testosterone concentration in untrained men.

Upper-body repeated-sprint training in hypoxia in international rugby union players

This study investigated the effects of upper-body repeated-sprint training in hypoxia vs. in normoxia on world-level male rugby union players' repeated-sprint ability (RSA) during an international competition period. Thirty-six players belonging to an international rugby union male national team performed over a 2-week period four sessions of double poling repeated-sprints (consisting of 3 × eight 10-s sprints with 20-s passive recovery) either in normobaric hypoxia (RSH, simulated altitude 3000 m, n = 18) or in normoxia (RSN, 300 m; n = 18). At pre- and post-training intervention, RSA was evaluated using a double-poling repeated-sprint test (6 × 10-s maximal sprint with 20-s passive recovery) performed in normoxia. Significant interaction effects (P < 0.05) between condition and time were found for RSA-related parameters. Compared to Pre-, peak power significantly improved at post- in RSH (423 ± 52 vs. 465 ± 69 W, P = 0.002, η²=0.12) but not in RSN (395 ± 65 vs. 397 ± 57 W). Averaged mean power was also significantly enhanced from pre- to post-intervention in RSH (351 ± 41 vs. 388 ± 53 W, P < 0.001, η²=0.15), while it remained unchanged in RSN (327 ± 49 vs. 327 ± 43 W). No significant change in sprint decrement (P = 0.151, η² = 0.02) was observed in RSH (-17 ± 2% vs. -16 ± 3%) nor RSN (-17 ± 2% vs. -18 ± 4%). This study showed that only four upper-body RSH sessions were beneficial in enhancing repeated power production in international rugby union players. Although the improvement from RSA to game behaviour remains unclear, this finding appears of practical relevance since only a short preparation window is available prior to international games.