International journal of sports physiology and performance最新文献

Purpose: This study sought to investigate the efficacy of Tabata-style high-intensity interval training (T-HIIT) on athletic performance in judoka and to determine the impact of the fecal organic acid profile before training on the improvement of athletic performance.

Methods: Twenty males from Aichi University Judo Club (10 high-level competitors and 10 others) were included. Physical fitness tests such as the Uchikomi shuttle run, countermovement jump, squat jump, and chin-ups using a judo uniform were performed before and after T-HIIT. Fecal samples were collected before T-HIIT to measure the fecal concentration of organic acids. The fecal characteristics were categorized using the Bristol Stool Scale.

Results: The mean number of repetitions of the Uchikomi shuttle run test significantly increased for all judoka following T-HIIT. However, improvements in other physical fitness tests varied, with some judoka showing improvements while others did not. The changes in countermovement jump (r = -.48, P = .029) and chin-ups using a judo uniform (r = -.45, P = .045) after T-HIIT were significantly negatively correlated with the fecal concentrations of succinic acid before T-HIIT. There was a significant correlation between the Bristol Stool Scale score and fecal concentrations of succinic acid (r = .45, P = .044). Compared with other compounds, the fecal concentrations of acetic acid and propionic acid were significantly greater in high-level competitors, while succinic acid concentrations tended to be lower.

Conclusions: T-HIIT effectively improved the specialized endurance of the judoka. Modifying the fecal organic acid profile, especially the fecal succinic acid concentration, may enhance the efficacy of athletic performance improvements achieved by T-HITT.

Purpose: The purpose of this study was to describe the implementation of menstrual-cycle (MC) and hormonal-contraceptive (HC) tracking among Gaelic Football players, including the characterization of MC status and symptomatology, and to examine the effect of MC and oral-contraceptive-pill phases on daily wellness.

Methods: Fourteen highly trained players (age 24.2 [3.5] y), including non-HC (n = 6), oral contraceptive pill (n = 7), and intrauterine system (n = 1) users, prospectively tracked their MC or HC alongside daily self-reported wellness measures for 4 months. A combination of calendar-based counting, urinary ovulation prediction testing, and a midluteal serum progesterone measurement was used to assess MC status.

Results: Only 2 non-HC players were eumenorrheic. Two players exhibited oligomenorrhea (cycle length, 39 [4] d), and ovulation was not detected in one of them. Luteal phase deficiency was indicated in 2 players (serum progesterone range <1.0-7.5 nmol·L-1). All players except 1 reported at least 1 negative MC-related symptom or HC side effect. Linear mixed-model analyses revealed that wellness measures were not affected by oral contraceptive pill phase (P > .05). Linear mixed-model analysis was not performed in non-HC users due to the small sample of eumenorrheic players (n = 2).

Conclusions: Diverse reproductive profiles were observed, including HC use and subtle MC irregularities that would likely go undetected without prospective MC tracking using biochemical outcomes. This highlights the value of incorporating ovulation testing and blood sampling when establishing the MC status of athletes in applied research and practice where feasible. Applied researchers should anticipate practical challenges, including inconsistencies in ovulation testing timings and the time scale required to assess MC status among athletes.

Purpose: The flight-time method (FT) is used for measuring vertical jump height (JH) in the field because of its convenience; however, FT overestimates JH when the lower limb is flexed at landing. Herein, we proposed a new method (ie, flight-time method modified [FTM]) to address the problem of FT and evaluate its validity and reliability.

Methods: A total of 24 men performed 6 countermovement jumps on force plates (sampling rate: 1000 Hz) while being recorded with a smartphone high-speed camera at 240 frames·s-1. JH was calculated by the impulse-momentum method (IM), FT, and FTM. For FTM, the flight time and JH were calculated based on the displacement of the greater-trochanter marker using a smartphone application.

Results: JH calculated using FT was significantly higher (P < .001) compared with JH calculated by IM; however, JH calculated by FTM showed no significant difference with JH calculated by IM. Furthermore, JH calculated by FTM, compared with JH calculated by FT (ρ = .882; 95% CI, .838-.914), exhibited a stronger, nearly perfect, and significantly positive correlation (ρ = .987; 95% CI, .982-.991) with JH calculated by IM and showed high reliability.

Conclusions: The FTM proposed in this study had higher concurrent validity compared with FT and a high reliability for measuring countermovement JH because it was not affected by lower-extremity flexion at landing. Therefore, practitioners should consider using FTM as a convenient, low-cost, reliable, and more valid method for measuring JH in the field.

Purpose: This study aimed to characterize core-temperature (Tc) responses of swimmers competing at the 2024 3-km World Aquatics Masters Open Water Swimming Championships.

Methods: Within a cross-sectional observational study design, swimmers (n = 48 [23 male, 25 female]) ingested a telemetric Tc pill 4 hours before their race. Water temperatures were 20.9 °C (male; mean wet-bulb-globe temperature 25.9 °C) and 20.5 °C (female; mean wet-bulb-globe temperature: 25.4 °C). Linear mixed models determined differences between males and females for race-start, mean in-race, and peak Tc. Random coefficient models determined relationships between (1) sex, race time, body mass index (BMI), body-mass change or age, and Tc peak; (2) sex, race time, BMI, body-mass change or age, and Tc nadir; (3) sex, Tc peak, BMI, body-mass change or age, and race time, and (4) sex, Tc peak, BMI, body-mass change, or age and race ranking.

Results: The mean in-race Tc was 37.8 °C (36.1-38.8 °C); however, there were highly variable individual Tc responses (-3.1 to +2.7 °C). One swimmer experienced mild hypothermia (Tc ≤ 35.0 °C), and 5 exceeded 39.0 °C, a risk factor for heat-related illness. There were no statistical differences between males and females for race-start, mean, and peak Tc (P ≥ .243). Higher peak Tc was associated with faster race time (P = .05), higher race rank (P = .027), and higher BMI (P = .001).

Conclusions: Highly variable Tc responses (-3.1 to +2.7 °C) were observed, demonstrating that organizers of mass-participation open-water swimming events should always be prepared for, and provide facilities to treat, swimmers experiencing cold-/heat-related health incidents during competition.

Purpose: To investigate the effects of 3 training volumes in the bench-press exercise performed with interrepetition rest periods, matched for fatigue, on strength gains and neuromuscular adaptations.

Methods: Forty-three resistance-trained men were randomized into 3 groups: low (LOW), moderate (MOD), and high (HIG) volume. The intensities increased from 70% to 85% of 1-repetition maximum (1RM) over the 8-week training period. Each session consisted of only 1 set with short interrepetition rest periods. LOW performed only 3 repetitions per session (8-wk total: 48 repetitions); MOD completed 15, 12, 10, and 8 repetitions per session with 70%, 75%, 80%, and 85% 1RM, respectively (8-wk total: 180); and HIG performed 24, 21, 18, and 15 repetitions per session with 70%, 75%, 80%, and 85% 1RM, respectively (8-wk total: 312). Progressive loading and fatigue tests were conducted in the bench-press exercise before and after the training period. Electromyography (EMG) signals from the triceps brachii were registered during these tests.

Results: HIG and MOD showed higher velocity loss than LOW (16% vs 12%). No significant group × time interaction was observed for any variable. All groups improved significantly in all strength-related variables, except for maximal unloaded velocity, where only MOD obtained significant gains. Only LOW and MOD induced significant improvements in EMG. MOD obtained the greatest effect sizes in almost all strength variables.

Conclusions: No significant differences were found in the performance gains obtained by each group despite the wide differences in the total volume accumulated by each group.

Purpose: To determine the effects of repeated Brazilian jiujitsu (BJJ) matches on neuromuscular fatigue in forearm-flexor and knee-extensor muscles.

Methods: Twelve BJJ athletes (8 men and 4 women) performed a simulated BJJ tournament composed of four 8-minute matches interspersed by 16-minute intervals. Neuromuscular fatigue was assessed via prematch to postmatch(es) reductions in maximal voluntary isometric contraction (MVIC), voluntary activation, and potentiated twitch force (Ptwpot) in the forearm-flexor and knee-extensor muscles.

Results: The MVIC of the knee extensors and forearm flexors reduced from prematch 1 to postmatch 2 and remained suppressed until postmatch 4 (P < .034). The voluntary activation of the knee extensors declined only after match 4, whereas the voluntary activation of the forearm flexors did not change throughout the matches (P = .102). Ptwpot of knee extensors decreased from prematch 1 to postmatch 1 (P < .001) and remained reduced until postmatch 4 (P < .001). Ptwpot of the forearm flexors reduced after every match (P < .010), with complete recovery occurring only before the second match (P = .99). The magnitude of the prematch-to-postmatch reduction in Ptwpot was lower in knee extensors than in forearm flexors (P = .044).

Conclusions: Repeated BJJ matches induced neuromuscular fatigue, mainly due to impairments in muscle contractile function (ie, peripheral fatigue). The time between BJJ matches seems to be insufficient to allow complete recovery of neuromuscular function, which may influence performance during subsequent matches.

Purpose: To investigate differences between females and males at lactate thresholds 1 (LT1) and 2 (LT2).

Methods: Twenty-four female and twenty male participants performed an incremental cycle-ergometer test until exhaustion, where LT1 and LT2 were determined in each volunteer.

Results: Power output at LT1 and LT2 was lower in females than in males (P < .001). In addition, power output relative to peak power was higher in females at LT1 and LT2 (P < .001). However, heart rate was higher in females than males at LT1 and LT2 (P = .008). Furthermore, the heart rate relative to maximal heart rate was higher in females compared with males at LT1 and LT2 (P = .002).

Conclusion: Females and males may be in a different metabolic situation at the same percentage of maximum. This study helps to reduce sex bias in science, and future guidelines should consider establishing exercise prescription recommendations according to sex.

Clinical trial: NCT06104150.

Purpose: To quantify and compare loads encountered in individual training sessions and games during noncongested and congested weeks in semiprofessional women basketball players.

Methods: Using an observational, longitudinal design, 12 players from the same team had their external (PlayerLoad, relative PlayerLoad, and total and high-intensity inertial movement analysis variables) and internal load (session rating of perceived exertion [sRPE], sRPE-load, percentage of heart rate peak, and modified summated-heart-rate-zones load) monitored across a regular season. Training and game data were categorized into noncongested (0-1 game) and congested weeks (2-3 games). Linear mixed models and Cohen d effect sizes were used for analyses.

Results: Comparisons between training sessions revealed higher (P < .05, d = 1.35-5.33) PlayerLoad, total inertial movement analysis, sRPE, and sRPE-load during training session 1 than training session 2 in congested weeks. Comparisons between training sessions and games revealed higher (P ≤ .001, d = 1.10-1.66) sRPE and sRPE-load during games than training sessions 1 and 2 in noncongested weeks, alongside higher (P ≤ .001, d = 1.87-3.55) sRPE during game 1 than training sessions 1 and 2 in congested weeks. Comparisons between games revealed higher (P < .05, d = 0.57-2.82) loads in game 3 during congested weeks compared with all other games.

Conclusions: Training appeared to be tapered in congested weeks, likely to account for upcoming increases in game loading, but remained relatively consistent across sessions during noncongested weeks. Individual game loads remained relatively consistent but were noticeably increased when a third game was played in the week.