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Carolina F. Wilke, Felipe Augusto P. Fernandes, Flávio Vinícius C. Martins, Anísio M. Lacerda, Fabio Y. Nakamura, Samuel P. Wanner and Rob Duffield

Purpose : To investigate the existence of faster vs slower recovery profiles in futsal and factors distinguishing them. Methods: 22 male futsal players were evaluated in countermovement jump, 10-m sprint, creatine kinase, total quality of recovery (TQR), and Brunel Mood Scale (fatigue and vigor) before and immediately and 3, 24, and 48 h posttraining. Hierarchical cluster analysis allocated players to different recovery profiles using the area under the curve (AUC) of the percentage differences from baseline. One-way ANOVA compared the time course of each variable and players’ characteristics between clusters. Results : Three clusters were identified and labeled faster recovery (FR), slower physiological recovery (SLphy), and slower perceptual recovery (SLperc). FR presented better AUC in 10-m sprint than SLphy (P = .001) and SLperc (P = .008), as well as better TQR SLphy (P = .018) and SLperc (P = .026). SLperc showed better AUC in countermovement jump than SLphy (P = .014) but presented worse fatigue AUC than SLphy (P = .014) and FR (P = .008). AUC of creatine kinase was worse in SLphy than in FR (P = .001) and SLperc (P < .001). The SLphy players were younger than SLperc players (P = .027), whereas FR were slower 10-m sprinters than SLphy players (P = .003) and SLperc (P = .013) and tended to have higher maximal oxygen consumption than SLphy (effect size =1.13). Conclusion : Different posttraining recovery profiles exist in futsal players, possibly influenced by their physical abilities and age/experience.

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Steven H. Doeven, Michel S. Brink, Barbara C.H. Huijgen, Johan de Jong and Koen A.P.M. Lemmink

During rugby sevens tournaments, it is crucial to balance match load and recovery to strive for optimal performance. Purpose: To determine changes in well-being, recovery, and neuromuscular performance during and after an elite women’s rugby sevens tournament and assess the influence of match-load indicators. Methods: Twelve elite women rugby sevens players (age = 25.3 [4.1]y, height = 169.0 [4.0] cm, weight = 63.9 [4.9] kg, and body fat = 18.6% [2.7%]) performed 5 matches during a 2-d tournament of the Women’s Rugby Sevens World Series. Perceived well-being (fatigue, sleep quality, general muscle soreness, stress levels, and mood), total quality of recovery, and countermovement-jump flight time were measured on match days 1 and 2, 1 d posttournament, and 2 d posttournament. Total distance; low-, moderate-, and high-intensity running; and physical contacts during matches were derived from global positioning system–based time–motion analysis and video-based notational analysis, respectively. Internal match load was calculated by session rating of perceived exertion and playing time (rating of perceived exertion × duration). Results: Well-being (P < .001), fatigue (P < .001), general muscle soreness (P < .001), stress levels (P < .001), mood (P = .005), and total quality of recovery (P < .001) were significantly impaired after match day 1 and did not return to baseline values until 2 d posttournament. More high-intensity running was related to more fatigue (r = −.60, P = .049) and a larger number of physical contacts with more general muscle soreness (r = −.69, P = .013). Conclusion: Perceived well-being and total quality of recovery were already impaired after match day 1, although performance was maintained. High-intensity running and physical contacts were predominantly related to fatigue and general muscle soreness, respectively.

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Mathew Hillier, Louise Sutton, Lewis James, Dara Mojtahedi, Nicola Keay and Karen Hind

The practice of rapid weight loss (RWL) in mixed martial arts (MMA) is an increasing concern but data remain scarce. The aim of this study was to investigate the prevalence, magnitude, methods, and influencers of RWL in professional and amateur MMA athletes. MMA athletes (N = 314; 287 men and 27 women) across nine weight categories (strawweight to heavyweight), completed a validated questionnaire adapted for this sport. Sex-specific data were analyzed, and subgroup comparisons were made between athletes competing at professional and amateur levels. Most athletes purposefully reduced body weight for competition (men: 97.2%; women: 100%). The magnitude of RWL in 1 week prior to weigh-in was significantly greater for professional athletes compared with those competing at amateur level (men: 5.9% vs. 4.2%; women: 5.0% vs. 2.1% of body weight; p < .05). In the 24 hr preceding weigh-in, the magnitude of RWL was greater at professional than amateur level in men (3.7% vs. 2.5% of body weight; p < .05). Most athletes “always” or “sometimes” used water loading (72.9%), restricting fluid intake (71.3%), and sweat suits (55.4%) for RWL. Coaches were cited as the primary source of influence on RWL practices (men: 29.3%; women: 48.1%). There is a high reported prevalence of RWL in MMA, at professional and amateur levels. Our findings, constituting the largest inquiry to date, call for urgent action from MMA organizations to safeguard the health and well-being of athletes competing in this sport.

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Manuel D. Quinones and Peter W.R. Lemon

Hydrothermally modified non-genetically modified organisms corn starch (HMS) ingestion may enhance endurance exercise performance via sparing carbohydrate oxidation. To determine whether similar effects occur with high-intensity intermittent exercise, we investigated the effects of HMS ingestion prior to and at halftime on soccer skill performance and repeated sprint ability during the later stages of a simulated soccer match. In total, 11 male university varsity soccer players (height = 177.7 ± 6.8 cm, body mass = 77.3 ± 7.9 kg, age = 22 ± 3 years, body fat = 12.8 ± 4.9%, and maximal oxygen uptake = 57.1 ± 3.9 ml·kg BM−1·min−1) completed the match with HMS (8% carbohydrate containing a total of 0.7 g·kg BM−1·hr−1; 2.8 kcal·kg BM−1·hr−1) or isoenergetic dextrose. Blood glucose was lower (p < .001) with HMS at 15 min (5.3 vs. 7.7 mmol/L) and 30 min (5.6 vs. 8.3 mmol/L) following ingestion, there were no treatment differences in blood lactate, and the respiratory exchange ratio was lower with HMS at 15 min (0.84 vs. 0.86, p = .003); 30 min (0.83 vs. 0.85, p = .004); and 45 min (0.83 vs. 0.85, p = .007) of the first half. Repeated sprint performance was similar for both treatments (p > .05). Soccer dribbling time was slower with isoenergetic dextrose versus baseline (15.63 vs. 14.43 s, p < .05) but not so with HMS (15.04 vs. 14.43 s, p > .05). Furthermore, during the passing test, penalty time was reduced (4.27 vs. 7.73 s, p = .004) with HMS. During situations where glycogen availability is expected to become limiting, HMS ingestion prematch and at halftime could attenuate the decline in skill performance often seen late in contests.

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Thomas Reeve, Ralph Gordon, Paul B. Laursen, Jason K.W. Lee and Christopher J. Tyler

Purpose: To investigate the effects of short-term, high-intensity interval-training (HIIT) heat acclimation (HA). Methods: Male cyclists/triathletes were assigned into either an HA (n = 13) or a comparison (COMP, n = 10) group. HA completed 3 cycling heat stress tests (HSTs) to exhaustion (60% W max; HST1, pre-HA; HST2, post-HA; HST3, 7 d post-HA). HA consisted of 30-min bouts of HIIT cycling (6 min at 50% W max, then 12 × 1-min 100%-W max bouts with 1-min rests between bouts) on 5 consecutive days. COMP completed HST1 and HST2 only. HST and HA trials were conducted in 35°C/50% relative humidity. Cycling capacity and physiological and perceptual data were recorded. Results: Cycling capacity was impaired after HIIT HA (77.2 [34.2] min vs 56.2 [24.4] min, P = .03) and did not return to baseline after 7 d of no HA (59.2 [37.4] min). Capacity in HST1 and HST2 was similar in COMP (43.5 [8.3] min vs 46.8 [15.7] min, P = .54). HIIT HA lowered resting rectal (37.0°C [0.3°C] vs 36.8°C [0.2°C], P = .05) and body temperature (36.0°C [0.3°C] vs 35.8°C [0.3°C], P = .03) in HST2 compared with HST1 and lowered mean skin temperature (35.4°C [0.5°C] vs 35.1°C [0.3°C], P = .02) and perceived strain on day 5 compared with day 1 of HA. All other data were unaffected. Conclusions: Cycling capacity was impaired in the heat after 5 d of consecutive HIIT HA despite some heat adaptation. Based on data, this approach is not recommended for athletes preparing to compete in the heat; however, it is possible that it may be beneficial if a state of overreaching is avoided.

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Gareth N. Sandford, Simon A. Rogers, Avish P. Sharma, Andrew E. Kilding, Angus Ross and Paul B. Laursen

Purpose: Anaerobic speed reserve (ASR), defined as the speed range from velocity associated with maximal oxygen uptake (vVO2max) to maximal sprint speed, has recently been shown to be an important tool for middle-distance coaches to meet event surge demands and inform on the complexity of athlete profiles. To enable field application of ASR, the relationship between gun-to-tape 1500-m average speed (1500v) and the vVO2max for the determination of lower landmark of the ASR was assessed in elite middle-distance runners. Methods: A total of 8 national and 4 international middle-distance runners completed a laboratory-measured vVO2max assessment within 6 wk of a nonchampionship 1500-m gun-to-tape race. ASR was calculated using both laboratory-derived vVO2max (ASR-LAB) and 1500v (ASR-1500v), with maximal sprint speed measured using radar technology. Results: 1500v was on average +2.06 ± 1.03 km/h faster than vVO2max (moderate effect, very likely). ASR-LAB and ASR-1500v mean differences were −2.1 ± 1.5 km/h (large effect, very likely). 1500v showed an extremely large relationship with vVO2max, r = .90 ± .12 (most likely). Using this relationship, a linear-regression vVO2max-estimation equation was derived as vVO2max (km/h) = (1500v [km/h] − 14.921)/0.4266. Conclusions: A moderate difference was evident between 1500v and vVO2max in elite middle-distance runners. The present regression equation should be applied for an accurate field prediction of vVO2max from 1500-m gun-to-tape races. These findings have strong practical implications for coaches lacking access to a sports physiology laboratory who seek to monitor and profile middle-distance runners.

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Rich D. Johnston

Purpose: To explore the relationship between technical errors during rugby league games, match success, and physical characteristics. Methods: A total of 27 semiprofessional rugby league players participated in this study (24.8 [2.5] y, 183.5 [5.3] cm, 97.1 [11.6] kg). Aerobic fitness, strength, and power were assessed prior to the start of the competitive season before technical performance was tracked during 22 competitive fixtures. Attacking errors were determined as any error that occurred in possession of the ball that resulted in a handover to the opposition. Defensive errors included line breaks, penalties, and missed or ineffective tackles. Match outcome, the zone on the field in which each error occurred, and the number of errors in an error chain (≤60 s between errors) were assessed. Results: During a loss, there were more defensive errors in the 0- to 40-m zone than when a match was won (effect size = 0.99 [0.04–1.94]). Error chains were a predictor of conceding a try (P = .0001, r 2 = .22), with the odds ratio increasing to 2.33 when there were 7 errors per chain. High lower-body strength was associated with fewer defensive errors for backs (Bayes factor = 3.67) and forwards (Bayes factor = 19.31); relative bench press was also important for backs (Bayes factor = 3.21). Conclusions: Fewer defensive errors occur in the 0- to 40-m zone during winning matches; lower-body strength is strongly associated with fewer defensive errors in rugby league players.

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Daniel G. Hursh, Marissa N. Baranauskas, Chad C. Wiggins, Shane Bielko, Timothy D. Mickleborough and Robert F. Chapman

Endurance exercise performance in hypoxia may be influenced by an ability to maintain high minute ventilation (V˙E) in defense of reduced arterial oxyhemoglobin saturation. Inspiratory muscle training (IMT) has been used as an effective intervention to attenuate the negative physiological consequences associated with an increased V˙E, resulting in improved submaximal-exercise performance in normoxia. However, the efficacy of IMT on hypoxic exercise performance remains unresolved. Purpose: To determine whether chronic IMT improves submaximal-exercise performance with acute hypoxic exposure. Methods: A total of 14 endurance-trained men completed a 20-km cycling time trial (TT) in normobaric hypoxia (fraction of inspired oxygen [FiO2] = 0.16) before and after either 6 wk of an IMT protocol consisting of inspiratory loads equivalent to 80% of sustained maximal inspiratory pressure (n = 9) or a SHAM protocol (30% of sustained maximal inspiratory pressure; n = 5). Results: In the IMT group, 20-km TT performance significantly improved by 1.45 (2.0%), P = .03, after the 6-wk intervention. The significantly faster TT times were accompanied by a higher average V˙E (pre vs post: 99.3 [14.5] vs 109.9 [18.0] L·min−1, P = .01) and absolute oxygen uptake (pre vs post: 3.39 [0.52] vs 3.60 [0.58] L·min−1, P = .010), with no change in ratings of perceived exertion or dyspnea (P > .06). There were no changes in TT performance in the SHAM group (P = .45). Conclusion: These data suggest that performing 6 wk of IMT may benefit hypoxic endurance exercise performance lasting 30–40 min.

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Fernando Naclerio, Eneko Larumbe-Zabala, Mar Larrosa, Aitor Centeno, Jonathan Esteve-Lanao and Diego Moreno-Pérez

The impact of animal protein blend supplements in endurance athletes is scarcely researched. The authors investigated the effect of ingesting an admixture providing orange juice and protein (PRO) from beef and whey versus carbohydrate alone on body composition and performance over a 10-week training period in male endurance athletes. Participants were randomly assigned to a protein (CHO + PRO, n = 15) or a nonprotein isoenergetic carbohydrate (CHO, n = 15) group. Twenty grams of supplement mixed with orange juice was ingested postworkout or before breakfast on nontraining days. Measurements were performed pre- and postintervention on body composition (by dual-energy X-ray absorptiometry), peak oxygen consumption (V˙O2peak), and maximal aerobic speed. Twenty-five participants (CHO + PRO, n = 12; CHO, n = 13) completed the study. Only the CHO + PRO group significantly (p < .05) reduced whole-body fat (mean ± SD) (−1.02 ± 0.6 kg), total trunk fat (−0.81 ± 0.9 kg), and increased total lower body lean mass (+0.52 ± 0.7 kg), showing close to statistically significant increases of whole-body lean mass (+0.57 ± 0.8 kg, p = .055). Both groups reduced (p < .05) visceral fat (CHO + PRO, −0.03 ± 0.1 kg; CHO, −0.03 ± 0.5 kg) and improved the speed at maximal aerobic speed (CHO + PRO, +0.56 ± 0.5 km/hr; CHO, +0.35 ± 0.5 km/hr). Although consuming animal protein blend mixed with orange juice over 10 weeks helped to reduce fat mass and to increase lean mass, no additional performance benefits in endurance runners were observed.

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Fernando Klitzke Borszcz, Artur Ferreira Tramontin and Vitor Pereira Costa

Purpose: Functional threshold power (FTP), determined as 95% of the average power during a 20-min time trial, is suggested as a practical test for the determination of the maximal lactate steady state (MLSS) in cycling. Therefore, the objective of the present study was to determine the validity of FTP in predicting MLSS. Methods: A total of 15 cyclists, 7 classified as trained and 8 as well trained (mean [SD] maximal oxygen uptake 62.3 [6.4] mL·kg−1·min−1, maximal aerobic power 329 [30] W), performed an incremental test to exhaustion, an FTP test, and several constant-load tests to determine the MLSS. The bias ± 95% limits of agreement (LoA), typical error of the estimate (TEE), and Pearson coefficient of correlation (r) were calculated to assess validity. Results: For the power-output measures, FTP presented a bias ± 95% LoA of 1.4% ± 9.2%, a moderate TEE (4.7%), and nearly perfect correlation (r = .91) with MLSS in all cyclists together. When divided by training level, the bias ± 95% LoA and TEE were higher in the trained group (1.4% ± 11.8% and 6.4%, respectively) than in the well-trained group (1.3% ± 7.4% and 3.0%, respectively). For the heart-rate measurement, FTP presented a bias ± 95% LoA of −1.4% ± 8.2%, TEE of 4.0%, and very large correlation (r = .80) with MLSS. Conclusion: Therefore, trained and well-trained cyclists can use FTP as a noninvasive and practical alternative to estimate MLSS.