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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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Rob van der Straaten, Oren Tirosh, William A. (Tony) Sparrow and Rezaul Begg

Minimum toe clearance (MTC ∼10–30 mm) is a hazardous mid-swing gait event, characterized by high-foot velocity (∼4.60 m·s−1) and single-foot support. This experiment tested treadmill-based gait training effects on MTC. Participants were 10 young (4 males and 6 females) and 10 older (6 males and 4 females) healthy ambulant individuals. The mean age, stature, and body mass for the younger group was 23 (2) years, 1.72 (0.10) m, and 67.5 (8.3) kg, and for older adults was 77 (9) years, 1.64 (0.10) m, and 71.1 (12.2) kg. Ten minutes of preferred speed treadmill walking (baseline) was followed by 20 minutes with MTC information (feedback) and 10 minutes without feedback (retention). There were no aging effects on MTC in baseline or feedback. The MTC in baseline for older adults was 14.2 (3.5) mm and feedback 27.5 (8.7) mm, and for the younger group, baseline was 12.7 (2.6) mm and feedback 28.8 (5.1) mm, respectively. Retention MTC was significantly higher for both groups, indicating a positive effect of augmented information: younger 40.8 (7.3) mm and older 27.7 (13.6) mm. Retention joint angles relative to baseline indicated that the young modulated joint angles control MTC differently using increased ankle dorsiflexion at toe off and modulating knee and hip angles later in swing closer to MTC.

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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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Rebecca A. Schlaff, Meghan Baruth, Faith C. LaFramboise and Samantha J. Deere

Background: Relationships among moderate to vigorous physical activity (MVPA), body satisfaction, and postpartum depressive symptoms are not well understood. The purpose of this study is to examine the (1) impact of postpartum body satisfaction and changes in MVPA on postpartum depressive symptoms and (2) moderating effect of changes in MVPA over time on the relationship between postpartum body satisfaction and depressive symptoms. Methods: Participants (N = 269) self-reported body satisfaction, MVPA (prepregnancy through postpartum), and postpartum depressive symptoms. Differences in MVPA at 3 time points (prepregnancy, third trimester, and postpartum) were calculated to create change scores. Main effects and interactions (body satisfaction × MVPA change) were examined using multiple regression. Results: A majority of the sample did not meet MVPA recommendations at all time points. All body satisfaction measures were inversely related to postpartum depressive symptoms (P = .01 to <.001). MVPA change did not predict postpartum depressive symptoms (P = .43–.90) or moderate the relationship between body satisfaction and postpartum depressive symptoms (P = .14–.94). Conclusions: Given the relationship between postpartum body satisfaction and depressive symptoms, intervention research should include strategies that promote positive postpartum body image; clinicians should consider screening for body dissatisfaction. Although not a predictor or moderator, pregnancy and postpartum MVPA promotion should continue, as it has numerous other benefits.

Open access

E. Kipling Webster, Leah E. Robinson and Danielle D. Wadsworth

Background: Activity breaks are an established way physical activity may be incorporated into the preschool day. The purpose of this study was to examine what factors influenced moderate to vigorous physical activity (MVPA) during a teacher-implemented classroom-based activity break (CBAB) in a Head Start population. Methods: Ten-minute CBAB was conducted over 2 days in a quasi-experimental design; 99 preschoolers (mean age 3.80 [0.65] y; 49.5% male) from a convenience sample participated. Accelerometers measured MVPA, fundamental motor skill competency was assessed using the Test of Gross Motor Development—second edition, and weight classification status used body mass index percentiles. Results: A significant, moderate regression was found (r = .328, P = .001) between fundamental motor skill and MVPA. There was no significant correlation between body mass index percentile and MVPA during the CBAB. In addition, the locomotor subscale was the best predictor for MVPA for children during the CBAB (r = .32, β = 0.82, P < .001). Conclusions: CBAB equally elicited MVPA for normal and overweight preschoolers. Fundamental motor skill competency was associated with MVPA during the CBAB; in particular, locomotor skills were the best predictor for physical activity. Structured activity opportunities that focus on locomotor skills may be a useful integration to prompt more MVPA in a preschool-age population.

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Marina Arkkukangas, Susanna Tuvemo Johnson, Karin Hellström, Elisabeth Anens, Michail Tonkonogi and Ulf Larsson

This study investigates the effectiveness of two fall-prevention exercise interventions targeting physical performance, activity level, fall-related self-efficacy, health-related quality of life, and falls: the Otago Exercise Programme (OEP) with and the OEP without behavior change support. In this randomized controlled trial, 175 participants were randomized into two intervention groups and one control group. A total of 124 community-dwelling older adults aged 75 and older who needed walking aids or home support participated in the 2-year follow-up. The OEP with and without support for behavior change displayed no long-term benefits on physical performance, fall-related self-efficacy, health-related quality of life, and falls compared with a control group. Although no significant differences were detected between the groups, the results implied the control group’s physical activity level decreased compared with the intervention groups at 2-year follow-up.

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Rosenda Murillo, Pooja Agrawal, Sheila Berenji-Jalaei, Elizabeth Vasquez and Sandra Echeverria

Background: Little research has examined gender differences in the association of seeing others exercise, in the neighborhood context, with physical activity, particularly for diverse racial/ethnic groups. The authors examined the association between frequency of seeing people walk and aerobic activity by gender among Latinos. Methods: The authors used cross-sectional 2015 National Health Interview Survey data on Latino participants ≥18 years (n = 5147). Multinomial logistic regression models estimated the association between seeing people walk and level of aerobic physical activity. Results: Men reporting seeing people walk every 2 to 3 days and every day were more likely to meet the aerobic activity recommendation (odds ratio [OR] 2.02; 95% confidence interval [CI], 1.05–3.89 and OR 1.96; 95% CI, 1.23–3.14, respectively). Among women, those seeing people walk every day and every 2 to 3 days were likely to engage in some aerobic activity (OR 1.88; 95% CI, 1.26–2.80 and OR 2.16; 95% CI, 1.23–3.18, respectively) and meet the recommendation (OR 1.73; 95% CI, 1.24–2.42 and OR 1.66; 95% CI, 1.03–2.67, respectively). Women seeing people walk about once a week were also likely to engage in some activity (OR 3.06; 95% CI, 1.59–5.89). Conclusions: Among Latino men and women, seeing people walk is associated with meeting the aerobic activity guideline. Results suggest that adoption of physical activity may in part be driven by neighborhood-level behavioral norms and by inference characteristics of the neighborhood that support walking.