The purpose of this trial was to examine the effects of self-selected exercise intensities plus either whey protein or placebo supplementation on vital signs, body composition, bone mineral density, muscle strength, and mobility in older adults. A total of 101 participants aged 55 years and older (males [n = 34] and females [n = 67]) were evaluated before and after 12 weeks of self-selected, free-weight resistance exercise plus 30 min of self-paced walking three times per week. The participants were randomized into two groups: whey protein (n = 46) or placebo (n = 55). Three-way mixed factorial analyses of variance were used to test for mean differences for each variable. The 12 weeks of self-selected, self-paced exercise intensities improved resting heart rate, fat-free mass, percent body fat, handgrip strength, bench press strength, leg press strength, and all mobility measurements (p < .05) in males and females despite supplementation status. This suggests that additional protein in well-fed healthy older adults does not enhance the benefit of exercise.
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Ashley A. Herda, Brianna D. McKay, Trent J. Herda, Pablo B. Costa, Jeffrey R. Stout and Joel T. Cramer
Chantelle Zimmer, Janice Causgrove Dunn and Nicholas L. Holt
Children with developmental coordination disorder (DCD) may experience stress in physical activity contexts due to emphasis on their poor motor skills. The purpose of this study was to explore the lived experiences of children at risk for DCD in physical education in order to develop a deeper understanding about what they experience as stress and how they cope with it. Using interpretative phenomenological analysis, six children in Grades 4–6 participated in two semistructured interviews. A motivational (and developmental) stress and coping theory informed interpretation of the three themes that described the children’s experiences: (a) they hurt me—psychological and physical harm sustained from peers, (b) it’s hard for me—difficulties encountered in activities, and (c) I have to—pressure to meet the teacher’s demands. Although the children at risk for DCD were confronted with various stressors in physical education, they coped more adaptively when social support was provided.
David Barranco-Gil, Jaime Gil-Cabrera, Pedro L. Valenzuela, Lidia B. Alejo, Almudena Montalvo-Pérez, Eduardo Talavera, Susana Moral-González and Alejandro Lucia
Purpose: The functional threshold power (FTP), which demarcates the transition from steady state to non-steady-state oxidative metabolism, is usually determined with a 20-minute cycling time trial that follows a standard ∼45-minute warm-up. This study aimed to determine if the standard warm-up inherent to FTP determination is actually necessary and how its modification or removal affects the relationship between FTP and the respiratory compensation point (RCP). Methods: A total of 15 male cyclists (age 35  y, maximum oxygen uptake 66.4 [6.8] mL·kg−1·min−1) participated in this randomized, crossover study. Participants performed a ramp test for determination of RCP and maximum oxygen uptake. During subsequent visits, they performed a 20-minute time trial preceded by the “standard” warm-up that is typically performed before an FTP test (S-WU), a 10-minute warm-up at the power output (PO) corresponding to 60% of maximum oxygen uptake (60%-WU), or no warm-up (No-WU). FTP was computed as 95% of the mean PO attained during the time trial. Results: Although the FTP was correlated with the RCP independently of the warm-up (r = .89, .93, and .86 for No-WU, 60%-WU, and S-WU, respectively; all Ps < .001), the PO at RCP was higher than the FTP in all cases (bias ± 95% limits of agreement = 57 , 60 , and 57  W for No-WU, 60%-WU, and S-WU, respectively; all Ps < .001 and effect size > 1.70). Conclusions: The FTP is highly correlated with the RCP but corresponds to a significantly lower PO, being these results independent of the warm-up performed (or even with no warm-up).
Jan-Michael Johansen, Sondre Eriksen, Arnstein Sunde, Øystein B. Slettemeås, Jan Helgerud and Øyvind Støren
Purpose: To investigate the effect of a double-poling (DP) high-intensity aerobic interval-training (HIT) intervention performed without increasing total HIT volume. This means that regular HIT training (eg, running) was replaced by HIT DP. The aim was to explore whether this intervention could improve peak oxygen uptake in DP, the fractional utilization of maximal oxygen uptake (VO2max) in DP, oxygen cost of DP, maximal aerobic speed, and a 3-km DP time trial. Methods: Nine non-specially-DP-trained cross-country skiers (intervention group) and 9 national-level cross-country skiers (control group) were recruited. All participants were tested for VO2max in running, peak oxygen uptake in DP, oxygen cost of DP, and time-trial performance before and after a 6-wk, 3-times-per-week HIT DP intervention. The intervention group omitted all regular HIT with HIT in DP, leaving the total weekly amount of HIT unchanged. Results: Seven participants in each group completed the study. VO2max in running remained unchanged in both groups, whereas peak oxygen uptake in DP improved by 7.1% (P = .005) in the intervention group. The fractional utilization of VO2max in DP thus increased by 7.3% (P = .019), oxygen cost of DP by 9.2% (P = .047), maximal aerobic speed by 16.5% (P = .009), and time trial by 19.5% (P = .004) in the intervention group but remained unchanged in the control group. Conclusions: The results indicate that a 6-wk HIT DP intervention could be an effective model to improve DP-specific capacities, with maintenance of VO2max in running.
Chiharu Iwasaka, Tsubasa Mitsutake and Etsuo Horikawa
Objectives: To investigate the relationship between leg skeletal muscle mass asymmetry and usual gait speed in older adults. Methods: The subjects were 139 community-dwelling older adults. The asymmetry index was calculated using the leg skeletal muscle mass index (LSMI) values of both legs. The subjects were divided into “large” and “small” asymmetry groups based on the asymmetry index. The relationship between asymmetry and gait speed was analyzed using a linear regression model. The appendicular skeletal muscle mass index and LSMI were included as adjustment variables in the analysis. Results: The asymmetry index and having a “large” asymmetry were independently related to gait speed, even after adjusting for covariates such as appendicular skeletal muscle mass index and LSMI. Discussion: Leg skeletal muscle mass asymmetry was related to gait speed independently of the appendicular skeletal muscle mass index and LSMI values. A skeletal muscle mass evaluation among older adults should include an assessment of the total skeletal muscle mass and its asymmetry.
Timothy J.H. Lathlean, Paul B. Gastin, Stuart V. Newstead and Caroline F. Finch
Purpose: To investigate the association between player wellness and injury in elite junior Australian football players over 1 competitive season. Methods: Prospective cohort study. Elite junior Australian football players (N = 196, average age = 17.7 y, range = 16–18 y) were recruited in the under-18 state league competition in Victoria, Australia. They recorded their wellness (sleep, fatigue, soreness, stress, and mood) according to a 5-point Likert scale 3 times weekly, with injuries (missed match/training session) entered into an online sport-injury surveillance system. A logistic generalized estimating equation was used to examine the association (expressed as odds ratio [OR]) between wellness and injury (yes/no). Results: Soreness was associated with injury at each time point across the week, with the strongest association evident for soreness reported 6 d postmatch (OR = 1.30; 95% confidence interval [CI], 1.17–1.44; P < .001). Stress and injury were associated with injury for average stress values across the week, as well as specifically on day 1 postmatch (OR = 1.10; 95% CI, 1.01–1.21; P = .038). Mood reported in the middle of the week (3 d postmatch) was associated with injury (OR = 0.87; 95% CI, 0.78–0.97; P = .014), as was fatigue (OR = 1.10; 95% CI, 1.00–1.22; P = .044). Conclusions: This study demonstrates key associations between wellness and injury in elite junior Australian football, specifically soreness, stress, fatigue, and mood. Monitoring strategies help identify injury-risk profiles, which can help decision makers (coaches or medical staff) intervene when relevant to reduce injury risk.
Fergus K. O’Connor, Steven E. Stern, Thomas M. Doering, Geoffrey M. Minett, Peter R. Reaburn, Jonathan D. Bartlett and Vernon G. Coffey
Context: Exercise in hot environments increases body temperature and thermoregulatory strain. However, little is known regarding the magnitude of effect that ambient temperature (Ta), relative humidity (RH), and solar radiation individually have on team-sport athletes. Purpose : To determine the effect of these individual heat-stress variables on team-sport training performance and recovery. Methods: Professional Australian Rules Football players (N = 45) undertook 8-wk preseason training producing a total of 579 outdoor field-based observations with Ta, RH, and solar radiation recorded at every training session. External load (distance covered, in m/min; percentage high-speed running [%HSR] >14.4 km/h) was collected via a global positioning system. Internal load (ratings of perceived exertion and heart rate) and recovery (subjective ratings of well-being and heart-rate variability [root mean square of the successive differences]) were monitored throughout the training period. Mixed-effects linear models analyzed relationships between variables using standardized regression coefficients. Results: Increased solar-radiation exposure was associated with reduced distance covered (−19.7 m/min, P < .001), %HSR (−10%, P < .001) during training and rMSSD 48 h posttraining (−16.9 ms, P = .019). Greater RH was associated with decreased %HSR (−3.4%, P = .010) but increased percentage duration >85% HRmax (3.9%, P < .001), ratings of perceived exertion (1.8 AU, P < .001), and self-reported stress 24 h posttraining (−0.11 AU, P = .002). In contrast, higher Ta was associated with increased distance covered (19.7 m/min, P < .001) and %HSR (3.5%, P = .005). Conclusions: The authors show the importance of considering the individual factors contributing to thermal load in isolation for team-sport athletes and that solar radiation and RH reduce work capacity during team-sport training and have the potential to slow recovery between sessions.
Thales M. Medeiros, João B. Ribeiro-Alvares, Carolina G. Fritsch, Gabriel S. Oliveira, Lucas Severo-Silveira, Evangelos Pappas and Bruno M. Baroni
Purpose: To examine the differences between performing Nordic hamstring exercises once or twice a week on hamstring eccentric strength and other muscle-strain risk factors in high-level football players. Methods: In this randomized trial, 32 football players (18–23 y old) completed an 8-week Nordic hamstring exercise training program in 1 of 2 experimental groups: group 1 (once a week; n = 15) and group 2 (twice a week; n = 17). Knee-flexor/extensor peak torques and biceps femoris long-head muscle architecture were assessed through isokinetic dynamometry and ultrasonography, respectively, before and after the training programs. Analysis of covariance, effect sizes (ESs), and t tests for percentage change were used to assess the effect of the 2 interventions on the outcome measures. Results: Group 2 demonstrated higher hamstring concentric peak torque than group 1 posttraining (155–164 vs 149–158 N·m; P = .043; ES = 0.27), although there was also a statistical trend for higher hamstring eccentric peak torque (212–234 vs 198–221 N·m; P = .098; ES = 0.37), hamstring-to-quadriceps conventional ratio (0.56–0.59 vs 0.54–0.57; P = .089; ES = 0.31), and hamstring-to-quadriceps functional ratio (0.76–0.84 vs 0.71–0.79; P = .076; ES = 0.50). No between-groups differences were found for muscle thickness (P = .864; ES = 0.12), pennation angle (P = .289; ES = 0.18), fascicle length (P = .406; ES = 0.03), and quadriceps concentric peak torque (P = .340; ES = 0.02). Conclusion: Only the Nordic hamstring exercise training program performed twice a week strengthened the hamstrings of high-level football players, while similar changes in muscle architecture occurred with both once- and twice-weekly sessions.
Jason Flindall, Scott Sinnett and Alan Kingstone
The length of the last visual fixation before the critical final phase of a movement—the quiet eye (QE) fixation—is positively correlated with expertise and success. The present study tested the potential for intraskill transfer of QE durations in order to determine whether it is intrinsically linked to expertise development or is a separable skill that may be employed to improve performance under novel circumstances. The authors tracked highly skilled dart throwers’ gazes while they executed familiar (highly practiced) and familiar yet novel (distance/effector-modified) sport-specific actions. QE duration was significantly reduced when performing in unfamiliar conditions, suggesting that QE does not transfer to atypical conditions and may therefore be a result of—rather than a contributor to—expertise development. These results imply that intraskill transfer of QE is limited and, consistent with the inhibition hypothesis of QE development, argue against the value of teaching QE as an independent means of improving performance.