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Cristiane B.B. Antonelli, Charlini S. Hartz, Sileno da Silva Santos and Marlene A. Moreno

Purpose: To evaluate the effects of inspiratory muscle training associated with interval training on respiratory muscle strength and fatigue and aerobic physical performance (PP) in high-performance wheelchair basketball athletes. Methods: Blinded, randomized clinical trial with 17 male wheelchair basketball players, randomized into control group (CG; n = 8) and training group (TG; n = 9). Respiratory muscle strength was evaluated by measuring maximal inspiratory and expiratory pressures (MIP and MEP), aerobic PP by the Yo-Yo test for wheelchair, and recovery of inspiratory muscle fatigue was assessed at 1, 5, 10, and 15 minutes after exercise test. TG performed inspiratory muscle training protocol with incremental loading for 12 weeks with 50%, 60%, and 70% of MIP, while CG performed with load 15% of MIP. Results: After training period, CG presented a significant increase in MIP and MEP (P ≤ .05), with no change in aerobic PP (P ≥ .05). TG showed a significant increase for all variables (≤.05). MIP showed a large effect size for CG (1.00) and TG (1.35), while MEP showed a moderate effect for CG (0.61) and TG (0.73); distance covered had a moderate effect size for TG (0.70). For recovery of inspiratory muscle strength, CG did not present differences, while TG recovered in 10 minutes (≤.05), representing 87% of the pretest value. Positive and significant correlation between MIP and distance (.54; P ≤ .05) was observed. Conclusion: Inspiratory muscle training protocol with progressive loading was more effective for increasing aerobic PP and maximal inspiratory strength recovery.

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João Ribeiro, Luís Teixeira, Rui Lemos, Anderson S. Teixeira, Vitor Moreira, Pedro Silva and Fábio Y. Nakamura

Purpose : The current study aimed to compare the effects of plyometric (PT) versus optimum power load (OPL) training on physical performance of young high-level soccer players. Methods : Athletes were randomly divided into PT (horizontal and vertical drills) and OPL (squat + hip thrust exercises at the load of maximum power output) interventions, applied over 7 weeks during the in-season period. Squat and countermovement jumps, maximal sprint (10 and 30 m), and change of direction (COD; agility t test) were the pretraining and posttraining measured performance variables. Magnitude-based inference was used for within- and between-group comparisons. Results : OPL training induced moderate improvements in vertical squat jump (effect size [ES]: 0.97; 90% confidence interval [CI], 0.32–1.61) and countermovement jump (ES: 1.02; 90% CI, 0.46–1.57), 30-m sprint speed (ES: 1.02; 90% CI, 0.09–1.95), and COD performance (ES: 0.93; 90% CI, 0.50–1.36). After PT training method, vertical squat jump (ES: 1.08; 90% CI, 0.66–1.51) and countermovement jump (ES: 0.62; 90% CI, 0.18–1.06) were moderately increased, while small enhancements were noticed for 30-m sprint speed (ES: 0.21; 90% CI, −0.02 to 0.45) and COD performance (ES: 0.53; 90% CI, 0.24–0.81). The 10-m sprint speed possibly increased after PT intervention (small ES: 0.25; 90% CI, −0.05 to 0.54), but no substantial change (small ES: 0.36; 90% CI, −0.40 to 1.13) was noticed in OPL. For between-group analyses, the COD ability and 30-m sprint performances were possibly (small ES: 0.30; 90% CI, −0.20 to 0.81; Δ = +1.88%) and likely (moderate ES: 0.81; 90% CI, −0.16 to 1.78; Δ = +2.38%) more improved in the OPL than in the PT intervention, respectively. Conclusions : The 2 different training programs improved physical performance outcomes during the in-season period. However, the combination of vertically and horizontally based training exercises (squat + hip thrust) at optimum power zone led to superior gains in COD and 30-m linear sprint performances.

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Arthur H. Bossi, Wouter P. Timmerman and James G. Hopker

Purpose: There are several published equations to calculate energy expenditure (EE) from gas exchanges. The authors assessed whether using different EE equations would affect gross efficiency (GE) estimates and their reliability. Methods: Eleven male and 3 female cyclists (age 33 [10] y; height: 178 [11] cm; body mass: 76.0 [15.1] kg; maximal oxygen uptake: 51.4 [5.1] mL·kg−1·min−1; peak power output: 4.69 [0.45] W·kg−1) completed 5 visits to the laboratory on separate occasions. In the first visit, participants completed a maximal ramp test to characterize their physiological profile. In visits 2 to 5, participants performed 4 identical submaximal exercise trials to assess GE and its reliability. Each trial included three 7-minute bouts at 60%, 70%, and 80% of the gas exchange threshold. EE was calculated with 4 equations by Péronnet and Massicotte, Lusk, Brouwer, and Garby and Astrup. Results: All 4 EE equations produced GE estimates that differed from each other (all P < .001). Reliability parameters were only affected when the typical error was expressed in absolute GE units, suggesting a negligible effect—related to the magnitude of GE produced by each EE equation. The mean coefficient of variation for GE across different exercise intensities and calculation methods was 4.2%. Conclusions: Although changing the EE equation does not affect GE reliability, exercise scientists and coaches should be aware that different EE equations produce different GE estimates. Researchers are advised to share their raw data to allow for GE recalculation, enabling comparison between previous and future studies.

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Matheus Barbalho, Victor S. Coswig, James Steele, James P. Fisher, Jurgen Giessing and Paulo Gentil

Purpose: To compare the effects of different resistance training volumes on muscle performance and hypertrophy in trained men. Methods: Thirty-seven volunteers performed resistance training for 24 weeks, divided into groups that performed 5 (G5), 10 (G10), 15 (G15), and 20 (G20) sets per muscle group per week. Ten-repetition maximum (10RM) tests were performed for the bench press, lat pulldown, 45° leg press, and stiff-legged deadlift. Muscle thickness was measured using ultrasound at biceps brachii, triceps brachii, pectoralis major, quadriceps femoris, and gluteus maximus. All measurements were performed at the beginning (pre), 12 (mid), and 24 weeks (post) of training. Results: All groups showed significant increases in all 10RM tests and muscle thickness measures after 12 and 24 weeks when compared with pre (P < .05). There were no significant differences in any 10RM test or changes between G5 and G10 after 12 and 24 weeks. G5 and G10 showed significantly greater increases for 10RM than G15 and G20 for most exercises at 12 and 24 weeks. There was no group by time interaction for any muscle thickness measure. Conclusions: The results bring evidence of an inverted “U-shaped” curve for the dose–response curve for muscle strength. Although the same trend was noted for muscle hypertrophy, the results did not reach significance. Five to 10 sets per week might be sufficient for bringing about optimal gains in muscle size and strength in trained men over a 24-week period.

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Fergus O’Connor, Heidi R. Thornton, Dean Ritchie, Jay Anderson, Lindsay Bull, Alex Rigby, Zane Leonard, Steven Stern and Jonathan D. Bartlett

Sprint capacity is an important attribute for team-sport athletes, yet the most appropriate method to analyze it is unclear. Purpose: To examine the relationship between sprint workloads using relative versus absolute thresholds and lower-body soft-tissue and bone-stress injury incidence in professional Australian rules football. Methods: Fifty-three professional Australian rules football athletes’ noncontact soft-tissue and bone-stress lower-body injuries (N = 62) were recorded, and sprint workloads were quantified over ∼18 months using the global positioning system. Sprint volume (m) and exposures (n) were determined using 2 methods: absolute (>24.9 km·h−1) and relative (≥75%, ≥80%, ≥85%, ≥90%, ≥95% of maximal velocity). Relationships between threshold methods and injury incidence were assessed using logistic generalized additive models. Incidence rate ratios and model performances’ area under the curve were reported. Results: Mean (SD) maximal velocity for the group was 31.5 (1.4), range 28.6 to 34.9 km·h−1. In comparing relative and absolute thresholds, 75% maximal velocity equated to ~1.5 km·h−1 below the absolute speed threshold, while 80% and 85% maximal velocity were 0.1 and 1.7 km·h−1 above the absolute speed threshold, respectively. Model area under the curve ranged from 0.48 to 0.61. Very low and very high cumulative sprint loads ≥80% across a 4-week period, when measured relatively, resulted in higher incidence rate ratios (2.54–3.29), than absolute thresholds (1.18–1.58). Discussion: Monitoring sprinting volume relative to an athlete’s maximal velocity should be incorporated into athlete monitoring systems. Specifically, quantifying the distance covered at >80% maximal velocity will ensure greater accuracy in determining sprint workloads and associated injury risk.

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Ben T. Stephenson, Sven P. Hoekstra, Keith Tolfrey and Victoria L. Goosey-Tolfrey

Purpose: Paratriathletes may display impairments in autonomic (sudomotor and/or vasomotor function) or behavioral (drinking and/or pacing of effort) thermoregulation. As such, this study aimed to describe the thermoregulatory profile of athletes competing in the heat. Methods: Core temperature (T c) was recorded at 30-second intervals in 28 mixed-impairment paratriathletes during competition in a hot environment (air temperature = 33°C, relative humidity = 35%–41%, and water temperature = 25°C–27°C), via an ingestible temperature sensor (BodyCap e-Celsius). Furthermore, in a subset of 9 athletes, skin temperature was measured. Athletes’ wetsuit use was noted while heat illness symptoms were self-reported postrace. Results: In total, 22 athletes displayed a T c ≥ 39.5°C with 8 athletes ≥40.0°C. There were increases across the average T c for swim, bike, and run sections (P ≤ .016). There was no change in skin temperature during the race (P ≥ .086). Visually impaired athletes displayed a significantly greater T c during the run section than athletes in a wheelchair (P ≤ .021). Athletes wearing a wetsuit (57% athletes) had a greater T c when swimming (P ≤ .032), whereas those reporting heat illness symptoms (57% athletes) displayed a greater T c at various time points (P ≤ .046). Conclusions: Paratriathletes face significant thermal strain during competition in the heat, as evidenced by high T c, relative to previous research in able-bodied athletes and a high incidence of self-reported heat illness symptomatology. Differences in the T c profile exist depending on athletes’ race category and wetsuit use.

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Yassine Negra, Helmi Chaabene, Senda Sammoud, Olaf Prieske, Jason Moran, Rodrigo Ramirez-Campillo, Ali Nejmaoui and Urs Granacher

Purpose: To examine the effects of loaded (LPJT) versus unloaded plyometric jump training (UPJT) programs on measures of muscle power, speed, change of direction (CoD), and kicking-distance performance in prepubertal male soccer players. Methods: Participants (N = 29) were randomly assigned to a LPJT group (n = 13; age = 13.0 [0.7] y) using weighted vests or UPJT group (n = 16; age = 13.0 [0.5] y) using body mass only. Before and after the intervention, tests for the assessment of proxies of muscle power (ie, countermovement jump, standing long jump); speed (ie, 5-, 10-, and 20-m sprint); CoD (ie, Illinois CoD test, modified 505 agility test); and kicking-distance were conducted. Data were analyzed using magnitude-based inferences. Results: Within-group analyses for the LPJT group showed large and very large improvements for 10-m sprint time (effect size [ES] = 2.00) and modified 505 CoD (ES = 2.83) tests, respectively. For the same group, moderate improvements were observed for the Illinois CoD test (ES = 0.61), 5- and 20-m sprint time test (ES = 1.00 for both the tests), countermovement jump test (ES = 1.00), and the maximal kicking-distance test (ES = 0.90). Small enhancements in the standing long jump test (ES = 0.50) were apparent. Regarding the UPJT group, small improvements were observed for all tests (ES = 0.33–0.57), except 5- and 10-m sprint time (ES = 1.00 and 0.63, respectively). Between-group analyses favored the LPJT group for the modified 505 CoD (ES = 0.61), standing long jump (ES = 0.50), and maximal kicking-distance tests (ES = 0.57), but not for the 5-m sprint time test (ES = 1.00). Only trivial between-group differences were shown for the remaining tests (ES = 0.00–0.09). Conclusion: Overall, LPJT appears to be more effective than UPJT in improving measures of muscle power, speed, CoD, and kicking-distance performance in prepubertal male soccer players.

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Oliver R. Barley, Dale W. Chapman, Georgios Mavropalias and Chris R. Abbiss

Purpose: To examine the influence of fluid intake on heat acclimation and the subsequent effects on exercise performance following acute hypohydration. Methods: Participants were randomly assigned to 1 of 2 groups, either able to consume water ad libitum (n = 10; age 23 [3] y, height 1.81 [0.09] m, body mass 87 [13] kg; HAW) or not allowed fluid (n = 10; age 26 [5] y, height 1.76 [0.05] m, body mass 79 [10] kg; HANW) throughout 12 × 1.5-h passive heat-acclimation sessions. Experimental trials were completed on 2 occasions before (2 baseline trials) and 1 following the heat-acclimation sessions. These sessions involved 3 h of passive heating (45°C, 38% relative humidity) to induce hypohydration followed by 3 h of ad libitum food and fluid intake after which participants performed a repeat sled-push test to assess physical performance. Urine and blood samples were collected before, immediately, and 3 h following hypohydration to assess hydration status. Mood was also assessed at the same time points. Results: No meaningful differences in physiological or performance variables were observed between HANW and HAW at any time point. Using pooled data, mean sprint speed was significantly (P < .001) faster following heat acclimation (4.6 [0.7] s compared with 5.1 [0.8] s). Furthermore, heat acclimation appeared to improve mood following hypohydration. Conclusions: Results suggest that passive heat-acclimation protocols may be effective at improving short-duration repeat-effort performance following acute hypohydration.

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Devin G. McCarthy and Lawrence L. Spriet

Background: Rest between training sessions can be short for athletes. In these situations, consuming carbohydrate (CHO) postexercise replenishes glycogen stores, which is important for recovery and subsequent performance. Purpose: This study tested whether CHO intake during a 2-hour rest between exercise bouts improved performance in the subsequent bout. Methods: In a randomized, single-blinded, crossover design, 10 recreationally active participants (23 [4] y, 70.8 [6.6] kg, 47.0 [5.4] mL·O2·min−1·kg·body·mass−1) arrived at the lab postprandial and completed 2 exercise bouts separated by a 2-hour rest. Bouts included 5 × 4-minute intervals at ∼80% peak oxygen consumption separated by 2 minutes at ∼40% peak oxygen consumption and ended with an endurance trial to voluntary exhaustion at ∼90% peak oxygen consumption. During intervals 1 and 4 in each bout, expired gases were collected and O2 deficit was estimated. Immediately following bout 1, either a CHO (1.2 g CHO·kg·body·mass−1) or placebo solution was consumed. Results: Endurance trial duration decreased in bout 2 versus 1 in both conditions (P < .01) but was ∼35% longer in bout 2 with CHO versus placebo (interaction, P = .03; post hoc, P = .03). Oxygen uptake increased during interval 4 versus 1 in both bouts (P < .01) but was unaffected by CHO (P ≥ .58). O2 deficit was unaffected by CHO (P = .93), bout, or interval (P ≥ .15). Perceived exertion was higher in bout 2 versus 1 (P < .001) and reduced in intervals 2 and 4 in CHO (P ≤ .01). Conclusions: When rest between training sessions is 2 hours, athletes may improve subsequent performance by consuming CHO during recovery.