Purpose: To analyze the differences in the force–velocity (F–v) profile assessed under unconstrained (ie, using free weights) and constrained (ie, on a Smith machine) vertical jumps, as well as to determine the between-day reliability. Methods: A total of 23 trained participants (18  y) performed an incremental load squat jump test (with ∼35%, 45%, 60%, and 70% of the subjects’ body mass) on 2 different days using free weights and a Smith machine. Nine of these participants repeated the tests on 2 other days for an exploratory analysis of between-day reliability. F–v variables (ie, maximum theoretical force [F 0], velocity [v 0], and power, and the imbalance between the actual and the theoretically optimal F–v profile) were computed from jump height. Results: A poor agreement was observed between the F–v variables assessed under constrained and unconstrained conditions (intraclass correlation coefficient [ICC] < .50 for all). The height attained during each single jump performed under both constrained and unconstrained conditions showed an acceptable reliability (coefficient of variation < 10%, ICC > .70). The F–v variables computed under constrained conditions showed an overall good agreement (ICC = .75–.95 for all variables) and no significant differences between days (P > .05), but a high variability for v 0, the imbalance between the actual and the theoretically optimal F–v profile, and maximal theoretical power (coefficient of variation = 17.0%–27.4%). No between-day differences were observed for any F–v variable assessed under unconstrained conditions (P > .05), but all of the variables presented a low between-day reliability (coefficient of variation > 10% and ICC < .70 for all). Conclusions: F–v variables differed meaningfully when obtained from constrained and unconstrained loaded jumps, and most importantly seemed to present a low between-day reliability.
Pedro L. Valenzuela, Guillermo Sánchez-Martínez, Elaia Torrontegi, Javier Vázquez-Carrión, Zigor Montalvo, and G. Gregory Haff
Ali Brian, Angela Starrett, Adam Pennell, Pamela Haibach-Beach, Emily Gilbert, Alexandra Stribing, Sally Taunton Miedema, and Lauren Lieberman
Youth with visual impairments are more likely to be overweight than peers without visual impairments and often struggle with their locomotor skills. Locomotor development can combat unhealthy body weight statuses by supporting physical activity behaviors. There are no longitudinal investigations concerning the locomotor skill and body mass index (BMI) developmental trajectories of youth with visual impairments. The purpose of this study was to examine the 3-year developmental trajectory of the locomotor skills and BMI of youth with visual impairments including differential effects of self-reported gender and degree of vision. Participants (N = 34, Mage = 11.75 years, 47% female) showed severely delayed and arrested locomotor development with increases in BMI across 3 years regardless of self-reported gender or degree of vision. Participants failed to breech a proficiency barrier of motor competence to combat against increases in BMI across time. Additional longitudinal inquiries are needed.
Ryota Ashizawa, Kazuma Yamashita, Koki Take, Kengo Okawara, Eri Mochizuki, Asuka Sakamoto, and Yoshinobu Yoshimoto
The purpose of this single-masked randomized clinical trial was to examine whether nonleisure-time physical activity guidance (NLTPAG) improves physical activity levels in patients after minor ischemic stroke. Patients who had been hospitalized for minor ischemic stroke in an acute care hospital (National Health Institute Stroke Scale ≤ 5) were randomized to either an NLTPAG group (n = 17) or a leisure-time physical activity guidance group (n = 16). NLTPAG focused on reducing sedentary behavior and increasing the frequency of walking for shopping and household activities to improve physical activity levels in daily life. Physical activity levels significantly improved only in participants in the NLTPAG group (initial assessment: metabolic equivalents of task = 12.6; final assessment: metabolic equivalents of task = 14.8; p = .035, r = .51). These results suggest that NLTPAG may be effective for improving physical activity levels in patients after minor ischemic stroke.
Joseph O.C. Coyne, Aaron J. Coutts, Robert U. Newton, and G. Gregory Haff
Purpose: To investigate the relationships between internal and external training load (TL) metrics with elite international women’s basketball performance. Methods: Sessional ratings of perceived exertion, PlayerLoad™/minute, and training duration were collected from 13 elite international-level female basketball athletes (age 29.0 [3.7] y, stature 186.0 [9.8] cm, body mass 77.9 [11.6] kg) during the 18 weeks prior to the International Basketball Federation Olympic qualifying event for the 2016 Rio Olympic Games. Training stress balance, differential load, and the training efficiency index were calculated with 3 different smoothing methods. These TL metrics and their change in the last 21 days prior to competition were examined for their relationship to competition performance as coach ratings of performance. Results: For a number of TL variables, there were consistent significant small to moderate correlations with performance and significant small to large differences between successful and unsuccessful performances. However, these differences were only evident for external TL when using exponentially weighted moving averages to calculate TL. The variable that seemed most sensitive to performance was the change in training efficiency index in the last 21 days prior to competition (performance r = .47–.56, P < .001 and difference between successful and unsuccessful performance P < .001, f2 = 0.305–0.431). Conclusions: Internal and external TL variables were correlated with performance and distinguished between successful and unsuccessful performances among the same players during international women’s basketball games. Manipulating TL in the last 3 weeks prior to competition may be worthwhile for basketball players’ performance, especially in internal TL.
Anis Aloulou, Francois Duforez, Damien Léger, Quentin De Larochelambert, and Mathieu Nedelec
Purpose: To evaluate the effects of sporting activities, training loads, and athletes’ characteristics on sleep among high-level adolescent athletes, in a controlled training and academic environment. Methods: A total of 128 high-level adolescent athletes (age = 15.2 [2.0] y), across 9 different sports, completed common sleep questionnaires and were monitored daily (7.3 [2.7] d) during a typical in-season training period. Sleep was analyzed using actigraphy and sleep diaries, whereas training load was evaluated using the session rating of perceived exertion, and muscle soreness and general fatigue were reported with the aid of visual analog scales. Separate linear mixed-effects models were fitted, including the athlete as a random effect and the following variables as fixed effects: the sport practiced (categorical predictor), daily training load, age, and sex. Different models were used to compare sleep variables among sports and to assess the influence of training load, age, and sex. Results: The mean total sleep time was 7.1 (0.7) hours. Swimmers presented increased sleep fragmentation, training loads, perceived muscle soreness, and general fatigue compared with athletes who engaged in other sports. Independent of any sport-specific effects, a higher daily training load induced an earlier bedtime and reduced total sleep time and perceived sleep quality, with higher sleep fragmentation. Moreover, female athletes experienced increased total sleep time and worse sleep quality in response to stress compared with those in males. Conclusion: In a controlled training and academic environment, high-level adolescent athletes did not achieve the recommended sleep duration. Impaired sleep quality and quantity could be partially explained by increased training loads.
Xiang Yao, Christopher Curtis, Anthony Turner, Chris Bishop, Alex Austerberry, and Shyam Chavda
Rugby union (RU) is a field-based team sport with a large number of high-intensity actions such as sprinting, change of direction, tackling, scrummaging, rucking, and mauling. Competitive success in female RU has previously been related to anthropometric and physical characteristics, and with the recent introduction of professionalism in female rugby, characterizing such physical attributes may provide insight into selection and training processes. Purpose: To identify anthropometric and physical characteristics of competitive female RU players and differences between playing positions. Methods: Twenty-two players were recruited from the top tier of female RU in the United Kingdom during the 2018–2019 Premiership season. Players were split into forwards and backs and underwent body composition testing via dual-X-ray absorptiometry and physical characteristic tests (10- and 20-m speed, 1-repetition-maximum bench press and squat, countermovement jump, drop jump, isometric midthigh pull, and 1200-m shuttle). Results: Moderate to large significant differences between playing positions in both anthropometric and physical characteristics were found (P < .01). Forwards displayed greater body mass (P = .03), fat mass (P = .01), and absolute upper-body strength (P = .03), whereas backs demonstrated superior countermovement jump height (P = .01), drop jump height (P = .01), greater reactive strength (P = .03), and speed (P = .03). Conclusion: These findings provide practitioners with a greater understanding of anthropometric and physical characteristics of professional female RU players.
T.N. Kirk, Justin A. Haegele, and Xihe Zhu
The purpose of this inquiry was to examine the relationship between barriers to physical activity, expectancy-value variables, and physical activity engagement among adults with visual impairments. Using a descriptive correlational approach, a sample of 214 adults with visual impairments (Mage = 43.14, SD = 13.67) completed questionnaires pertaining to barriers to physical activity, expectancy-value beliefs about physical activity, and physical activity engagement. Data were analyzed via correlation and hierarchical regression. The final regression model explained 20.30% of variance in physical activity (p < .001). Intrinsic value (β = 0.26, p = .01) and expectancy beliefs (β = 0.33, p < .001) each emerged as significant predictors of physical activity engagement, which suggests that expectancy-value theory may have some utility for investigating the physical activity engagement of individuals with visual impairments. However, the lack of significant contribution of other variables such as attainment and utility values, as well as barriers factors, underscores the need for additional research in this area.
Manuel Matzka, Christoph Zinner, Philipp Kunz, Hans-Christer Holmberg, and Billy Sperlich
Purpose: (1) To compare various physiological indicators of performance during a 5 × 1500-m incremental kayak test performed on an ergometer and on-water and (2) to analyze the relationships between these indicators and the actual competition performance of elite sprint kayakers, aiming to provide information to coaches for evaluating and planning training on-water. Methods: A total of 14 male and female German elite sprint kayakers performed an incremental test both on an ergometer and on-water. The tissue saturation index of the musculus (m.) biceps brachii, oxygen consumption, ratings of perceived exertion, and levels of blood lactate were measured and compared with actual racing times. In addition, power output was monitored during ergometer testing only. Results: Oxygen consumption during the fourth (P = .02; d = 0.32) and final (fifth; P < .001; d = 0.32) steps of incremental testing was higher on-water than on the ergometer. The tissue saturation index of the m. biceps brachii was approximately 21% higher at the end of the ergometer test (P = .002; d = 1.14). During the second (P = .01; d = 0.78), third (P = .005; d = 0.93), and fourth stages (P = .005; d = 1.02), the ratings of perceived exertion for ergometer kayaking was higher. During the final step, power output was most closely correlated to 200- (r = .88), 500- (r = .93), and 1000-m (r = .86) racing times (all Ps < .01). Conclusions: During high-intensity kayaking on an ergometer or on-water, the oxygen consumption and tissue saturation index of the m. biceps brachii differ. Furthermore, at moderate to submaximal intensities, the ratings of perceived exertion were higher for ergometer than for on-water kayaking. Finally, of all parameters assessed, the power output during ergometer kayaking exhibited the strongest correlation with actual racing performance.
Bethany Northeast and Tom Clifford
This systematic review and meta-analysis examined the effects of creatine supplementation on recovery from exercise-induced muscle damage, and is reported according to the PRISMA guidelines. MEDLINE and SPORTDiscus were searched for articles from inception until April 2020. Inclusion criteria were adult participants (≥18 years); creatine provided before and/or after exercise versus a noncreatine comparator; measurement of muscle function recovery, muscle soreness, inflammation, myocellular protein efflux, oxidative stress; range of motion; randomized controlled trials in humans. Thirteen studies (totaling 278 participants; 235 males and 43 females; age range 20–60 years) were deemed eligible for analysis. Data extraction was performed independently by both authors. The Cochrane Collaboration Risk of Bias Tool was used to critically appraise the studies; forest plots were generated with random-effects model and standardized mean differences. Creatine supplementation did not alter muscle strength, muscle soreness, range of motion, or inflammation at each of the five follow-up times after exercise (<30 min, 24, 48, 72, and 96 hr; p > .05). Creatine attenuated creatine kinase activity at 48-hr postexercise (standardized mean difference: −1.06; 95% confidence interval [−1.97, −0.14]; p = .02) but at no other time points. High (I2; >75%) and significant (Chi2; p < .01) heterogeneity was identified for all outcome measures at various follow-up times. In conclusion, creatine supplementation does not accelerate recovery following exercise-induced muscle damage; however, well-controlled studies with higher sample sizes are warranted to verify these conclusions. Systematic review registration (PROSPERO CRD42020178735).
Miguel Sánchez-Moreno, David Rodríguez-Rosell, David Díaz-Cueli, Fernando Pareja-Blanco, and Juan José González-Badillo
Purpose: This study analyzed the effects of 3 training interventions: 1 isolated endurance training (ET) and 2 concurrent training (CT), which differed in the velocity loss (VL) magnitude allowed during the resistance training (RT) set: 15% (VL15) versus 45%, on strength and endurance running performance. Methods: A total of 33 resistance- and endurance-trained men were randomly allocated into 3 groups: VL15, VL 45%, and ET. ET was similar across all groups. The CT groups differed in the VL allowed during the RT set. Before and after the 8-week training program the following tests were performed: (1) running sprints, (2) vertical jump, (3) progressive loading test in the squat exercise, and (4) incremental treadmill running test up to maximal oxygen uptake. Results: Significant differences (P < .001) in RT volume (approximately 401 vs 177 total repetitions for VL 45% and VL15, respectively) were observed. Significant “group” × “time” interactions were observed for vertical jump and all strength-related variables: the CT groups attained significantly greater gains than ET. Moreover, a significant “group” × “time” interaction (P = .03) was noted for velocity at maximal oxygen uptake. Although all groups showed increases in velocity at maximal oxygen uptake, the VL15 group achieved greater gains than the ET group. Conclusions: CT interventions experienced greater strength gains than the ET group. Although all groups improved their endurance performance, the VL15 intervention resulted in greater gains than the ET approach. Therefore, moderate VL thresholds in RT performed during CT could be a good strategy for concurrently maximizing strength and endurance development.