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Kristin S. Ondrak and Don W. Morgan

The influence of height, body mass, daily physical activity (DPA), and dietary calcium intake (DCI) on bone mineral density (BMD) and content (BMC) was evaluated in 33 four-year-old girls. Results indicated that body mass was significantly correlated with and predictive of BMD and BMC at all sites except the femoral neck BMD. DPA and height also explained a significant proportion of the variance in femoral neck BMD and BMC of the lumbar spine and total body. DCI was not related to or predictive of BMD or BMC at any bone site. These findings highlight the importance of engaging in daily weight-bearing physical activity to promote bone health in young girls.

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David W. Hill, Robert P. Steward Jr. and Cindy J. Lane

The purpose of this study was to evaluate use of the critical power concept with swimmers ages 8 to 18 years. Critical velocity (CV) and anaerobic swimming capacity (ASC) were determined from the results of three short time trials (n = 86) or competition swims (n = 60). Data fit the critical power model well, as evidenced by high R2 and low SEE of CV and ASC estimates. CV was correlated with velocity in an endurance swim (r ≥ 0.86) and ASC was correlated with peak lactate (r ≥ 0.69). Thus, even in very young swimmers, CV and ASC provide mode-specific indices of endurance and anaerobic capacity, respectively.

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Scott Rathwell and Bradley W. Young

emerging adulthood is also a period of life where significant personal and psychosocial development occurs ( Arnett, 2000 ), the study of positive development within emerging adult athlete cohorts has received less empirical attention than younger populations ( Rathwell & Young, 2016 ). The existing

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Frances E. Cleland

Young children’s (N = 50) divergent movement ability (DMA), which is one aspect of critical thinking in physical education, was examined in this study. Treatment Group A received 20 physical education lessons based on skill themes using indirect teaching styles (n = 16). Twenty lessons based on low-organized games content using direct teaching styles were provided to Treatment Group B (n = 17). No treatment was provided to the control subjects in Group C (n = 17). No significant DMA pretest differences were determined, and the independent variables (i.e., gender, intelligence, creativity, and background of movement experience) examined were not significantly related to subjects’ pretest DMA. A two-way ANOVA and post hoc Scheffe test revealed that Group A’s posttest DMA scores were significantly higher than those for either Group B or Group C, F(2, 47) = 11.7, p < .0001. Young children’s ability to generate different movement patterns (i.e., DMA), therefore, was significantly improved in response to employing critical thinking strategies in physical education.

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Kate A. Heelan and Joey C. Eisenmann

Background:

It is uncertain as to whether physical activity (PA) may influence the body composition of young children.

Purpose:

To determine the association between PA, media time, and body composition in children age 4 to 7 y.

Methods:

100 children (52 girls, 48 boys) were assessed for body-mass index (BMI), body fat, fat mass (FM), and fat-free mass using dual energy x-ray absorbtiometryptiometry (DXA). PA was monitored using accelerometers and media time was reported by parental proxy.

Results:

In general, correlations were low to moderate at best (r < 0.51), but in the expected direction. Total media time and TV were significantly associated with BMI (r = 0.51, P < 0.05) and FM (r = 0.29 to 0.30, P < 0.05) in girls. In boys, computer usage was significantly associated with FM in boys (r = 0.31, P < 0.05).

Conclusion:

The relatively low correlations suggest that other factors may influence the complex, multi-factorial body composition phenotype of young children.

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Sara López-Martínez, Mairena Sánchez-López, Montserrat Solera-Martinez, Natalia Arias-Palencia, Rosa M. Fuentes-Chacón and Vicente Martínez-Vizcaíno

Purpose:

Our objective was to analyze the association between different intensities of physical activity (PA), physical fitness, and metabolic syndrome (MS) in young adults.

Methods:

Cross-sectional study including 275 university students, 18–30 years old, from Cuenca, Spain. We evaluated (a) physical activity using accelerometry, (b) aerobic capacity (VO2max), and (c) muscle strength, by a muscle strength index calculated as the sum of the standardized z score of handgrip dynamometry/weight and standing broad jump. An MS index was estimated by summing standardized z scores of waist circumference, ratio of triglycerides to high-density lipoprotein, mean arterial blood pressure, and HOMA-IR.

Results:

The mean scores of MS index and HOMAIR were significantly higher and the VO2max significantly lower for individuals who did not perform 20 min or more per week of vigorous physical activity. However, those who performed 250 min/week of moderate physical activity showed no significant differences in either VO2max or the MS index when compared with individuals who did not perform this level of activity. The MS index was lower in those with medium-high levels of aerobic capacity. In addition, individuals with medium-high levels of muscular fitness showed lower waist circumference and a lower MS index.

Conclusions:

VO2max and muscle strength are negatively associated with metabolic risk. 20-min/week of vigorous physical activity was associated with lower cardiometabolic risk in young adults; moderate physical activity did not show association with lower cardiometabolic risk.

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Tiago M. Barbosa, Jorge E. Morais, Mário J. Costa, José Goncalves, Daniel A. Marinho and António J. Silva

The aim of this article has been to classify swimmers based on kinematics, hydrodynamics, and anthropometrics. Sixty-seven young swimmers made a maximal 25 m front-crawl to measure with a speedometer the swimming velocity (v), speed-fluctuation (dv) and dv normalized to v (dv/v). Another two 25 m bouts with and without carrying a perturbation device were made to estimate active drag coefficient (CD a). Trunk transverse surface area (S) was measured with photogrammetric technique on land and in the hydrodynamic position. Cluster 1 was related to swimmers with a high speed fluctuation (ie, dv and dv/v), cluster 2 with anthropometrics (ie, S) and cluster 3 with a high hydrodynamic profile (ie, CD a). The variable that seems to discriminate better the clusters was the dv/v (F = 53.680; P < .001), followed by the dv (F = 28.506; P < .001), CD a (F = 21.025; P < .001), S (F = 6.297; P < .01) and v (F = 5.375; P = .01). Stepwise discriminant analysis extracted 2 functions: Function 1 was mainly defined by dv/v and S (74.3% of variance), whereas function 2 was mainly defined by CD a (25.7% of variance). It can be concluded that kinematics, hydrodynamics and anthropometrics are determinant domains in which to classify and characterize young swimmers’ profiles.

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Kristin Wiens, Kelly Anne Erdman, Megan Stadnyk and Jill A. Parnell

Purpose:

To evaluate dietary supplement use in young Canadian athletes, their motivation for consuming supplements, and their sources of information.

Methods:

A questionnaire tested for content validity and reliability was administered to 567 athletes between the ages of 11 and 25 years from the Canadian athletic community in face-to-face meetings. Demographics and sport variables were analyzed using descriptive statistics. Fisher’s exact tests were used to examine dietary supplementation patterns and sources of information regarding dietary supplement use between categories of gender, age, sport type, and competition level.

Results:

Ninety-eight percent of athletes were taking at least one dietary supplement. Males were more likely to consume protein powder, energy drinks, recovery drinks, branched chain amino acids, beta-alanine, and glutamine (p < .01); supplements typically associated with increased muscle mass. Athletes 11–17 years old focused on vitamin and mineral supplements; whereas, athletes 18–25 years old focused on purported ergogenic supplements. Strength training athletes were more likely to consume creatine, glutamine, and protein powders (p < .02). Reasons for supplement use included to stay healthy, increase energy, immune system, recovery, and overall performance. Primary sources of information were family and friends, coaches, and athletic trainers; with 48% of athletes having met with a dietitian. Preferred means of education included individual consultations, presentations, and the internet.

Conclusions:

The majority of young athletes are using dietary supplements with the belief they will improve performance and health; however, may not always have reliable information. Educational programs using individual consultations and electronic media are recommended for this demographic.

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Deborah L. Feltz and Eugene W. Brown

Harter's (1979) perceived competence subscale was modified to specifically apply to soccer in order to compare young soccer players' general self-esteem, perceived physical competence, and perceived soccer competence scores in predicting players' actual soccer ability. Young soccer players (N = 217), 8 to 13 years of age, were tested on five soccer skill tests. Players also completed Harter's (1979) Perceived Competence Scale for Children and our perceived soccer competence subscale. We hypothesized that perceived soccer competence would have high internal consistency and would be a better predictor of soccer ability than either perceived physical competence or general self-esteem. Results indicated that the perceived soccer competence subscale had the highest internal consistency reliability coefficient, and that it was also slightly more predictive of soccer ability than perceived physical competence as indicated by multivariate multiple regression analysis and canonical correlation analysis. Future studies investigating perceived competence as a motivational variable in specific youth sports may find the sport-specific perceived competence measure to provide additional information to Harter's questionnaire.

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Camilla Astley, Diego Souza and Marcos Polito

Purpose:

To compare the acute effect of caffeine ingestion on performance in young judo athletes.

Method:

In a randomized double-blind design, eighteen judo athletes (16.1 ± 1.4 yrs.) were evaluated on three nonconsecutive days. On the first day, the special judo fitness test (SJFT) was used as a control session. On the second day, the sample was randomly divided into two equal groups. One group received 4 mg.kg-1 of caffeine (capsule) and the other group received a placebo. After resting for 60 min, the sample performed the SJFT. On the final day of testing, the same procedure was performed but the substance ingested was exchanged between the groups.

Results:

Heart rate (HR) and rating of perceived exertion (RPE) were recorded throughout the applications of the SJFTs. Caffeine ingestion did not induce changes in HR, but reduced the RPE compared with the placebo session (7.0 ± 1.1 vs 8.2 ± 2.0; p < .05), increased the number of throws applied (29.0 ± 2.6 vs 22.1 ± 3.4; p < .01) and reduced the SJFT index (12.2 ± 0.5 vs. 15.7 ± 0.9; p < .001).

Conclusion:

4 mg.kg-1 did not alter HR but improved performance on SJFT in young judo athletes and reduced the RPE.