The effectiveness of a twice-a-week strength training program on children was evaluated in 14 boys and girls (mean age 10.8 yrs) who participated in a biweekly training program for 8 weeks. Each subject performed three sets of 10 to 15 repetitions on five exercises with intensities ranging between 50 and 100% of a given 10-repetition maximum (RM). All subjects were pre- and posttested on the following measures: 10-RM strength, sit and reach flexibility, vertical jump, seated ball put, resting blood pressure, and body composition parameters. The subjects were compared to a similar group of boys and girls (n = 9; mean age 9.9 yrs) who were randomly selected to serve as controls. Following the training period, the experimental group made greater gains in strength (74.3%) as compared to the control group (13.0%) (p < 0.001), and differences in the sum of seven skinfolds were noted (−2.3% vs. +1.7%, respectively, p < 0.05). Training did not significantly affect other variables. These results suggest that participation in a short-term, twice-a-week strength training program can increase the strength and improve the body composition of young boys and girls.
Avery D. Faigenbaum, Leonard D. Zaichkowsky, Wayne L. Westcott, Lyle J. Micheli and Allan F. Fehlandt
Diane Austrin Klein, William J. Stone, Wayne T. Phillips, Jaime Gangi and Sarah Hartman
The impact of proprioceptive neuromuscular facilitation (PNF) on physical function in assisted-living older adults (73-94 years old) was studied. A 5-week pretraining period consisting of weekly visits by trainers to participants preceded a 10-week training period of warm-up, PNF exercises, and cool-down. Training progressed from 1 set of 3 repetitions to 3 sets of 3 repetitions. Assessments were conducted at baseline (T1), postpretraining (T2), and posttraining (T3). Eleven of 14 volunteer participants completed the study. Physical function was assessed by range of motion (ROM), isometric strength, and balance and mobility measures. Repeated-measures ANOVA identified 6 measures (sit-to-stand, shoulder- and ankle-flexion ROM, and hip-extension, ankle-flexion, and ankle-extension strength) with statistically significant differences. With the exception of hip-extension strength, these measures were statistically significant from T2 to T3 in post hoc univariate tests. Results indicate that PNF flexibility training can improve ROM, isometric strength, and selected physical-function tasks in assisted-living older adults.
Selenia di Fronso, Fabio Y. Nakamura, Laura Bortoli, Claudio Robazza and Maurizio Bertollo
The aim of the study was to examine differences in stress and recovery across gender and time (preseason and play-offs) in a sample of amateur basketball players of the Italian league (C division). Fifty amateur basketball players (33 men and 17 women) age 17–30 y (23.5 ± 9.19 y) participated in the study. Twenty-eight athletes (16 men and 12 women) completed the Recovery-Stress Questionnaire for Sport (RESTQ-Sport) in the preseason phase, after a training period of 21 days, and in the competition phase during the play-off period. Repeated-measures MANOVA showed significant differences by gender and preparation phase. Univariate follow-up ANOVA highlighted differences by gender on physical recovery, sleep quality, and self-efficacy, with higher scores in men. Moreover, differences between preseason and competition phases were shown on emotional stress and fatigue, with higher scores on emotional stress and lower scores on fatigue in the competition phase. These findings suggest that RESTQ-Sport could be a useful tool for coaches to monitor stress/recovery balance in male and female team-sport athletes during different periods of the season.
Judith A. Siegel, David N. Camaione and Thomas G. Manfredi
To assess the effects of a group resistance exercise program on prepubescent children, an experimental group of boys (n = 26) and girls (n = 24), with a mean age of 8.4 ± 0.5 years, participated in 12 weeks of school based training. The program consisted of upper body exercise using hand-held weights, stretch tubing, balls, and self-supported movements. A control group of boys (n = 30) and girls (n = 16), mean age 8.6 ± 0.5 years, had a free-play period. Boys were significantly stronger than girls on all initial strength evaluations and were taller and had lesser skinfold sums. ANCOVA was used to evaluate pre/post changes in cable tensiometer elbow flexion and extension, right and left handgrip strength, pull-ups, flexed arm hang, sit-ups, sit-and-reach flexibility, and body composition parameters. Following the training period, significantly greater gains were made by the experimental group for right handgrip, flexed arm hang, pull-ups, and flexibility. Greater decreases in sum of skinfolds were also found. Training responses of boys and girls were similar. It was concluded that a group strength training program can be an effective means of increasing fitness levels and improving body composition in both boys and girls of this age.
Michael Svensson, Christer Malm, Michail Tonkonogi, Bjǒrn Ekblom, Bertil Sjödin and Kent Sahlin
The aim of the present study was to investigate the concentration of ubiquinone-10 (Q10), at rest, in human skeletal muscle and blood plasma before and after a period of high-intensity training with or without Q10 supplementation. Another aim was to explore whether adenine nucleotide catabolism, lipid peroxidation, and mitochondrial function were affected by Q10 treatment. Seventeen young healthy men were assigned to either a control (placebo) or a Q10-supplementation (120 mg/day) group. Q10 supplementation resulted in a significantly higher plasma Q10/lotal cholesterol level on Days 11 and20compared with Day 1. There was no significant change in the concentration of Q10 in skeletal muscle or in isolated skeletal muscle mitochondria in either group. Plasma hypoxanthine and uric acid concentrations increased markedly after each exercise test session in both groups. After the training period, the postexercise increase in plasma hypoxanthine was markedly reduced in both groups, but the response was partially reversed after the recovery period. It was concluded that Q10 supplementation increases the concentration of Q1O in plasma but not in skeletal muscle.
Claudia Ridel Juzwiak and Fabio Ancona-Lopez
The objectives of this study were to describe the dietary practices recommended by coaches working with adolescent athletes and to assess their nutritional knowledge. During a regional competition in the state of São Paulo, Brazil, 55 coaches were interviewed. These coaches represented 22 cities with athletes enrolled in Olympic gymnastics, tennis, swimming, and judo events. A 3- section questionnaire was used to obtain data on demographic characteristics, dietary recommendations, and nutrition knowledge. Results showed that all coaches recommended general dietary practices during training, with no specific strategies for pre-, during-, and post-training periods. The main objectives of the recommendations for the training period were weight control and muscle mass gain. Deleterious weight control practices were recommended by 27% of the coaches. Specific dietary practices pre and post competition were recommended by 93% and 46% of the coaches, respectively. Participants responded correctly to 70% (SD = 3.2) of the nutrition knowledge questions, with no significant differences (p = .61) between sports. The knowledge test identified a tendency to overvalue proteins, excessively low-fat diets, and food myths. These findings indicate the importance of developing strategies that will enhance the nutritional training of coaches.
The aim of this investigation was to assess the influence of an 8-month physical training period on left ventricular voltages identified by resting ECG in relation to changes in left ventricle mass in adolescent athletes.
The study encompassed 28 adolescents aged 13 years (14 boys and 14 girls) from a sports secondary school. Clinical assessment was performed on all athletes before and after 8 months of physical training.
Sokolov-Lyon voltage index, Cornell voltage index, and maximum spatial QRS vector magnitude demonstrated statistically significant decline during the study period. The specific potential of the myocardium also significantly decreased during 8 months of training. The Sokolov-Lyon voltage criterion for left ventricular hypertrophy was fulfilled in 9 athletes (32.1%) at the beginning of the observation and only in 3 athletes (10.7%) at the end of the study. On the other hand, mean left ventricular mass and mean left ventricular mass index significantly increased after long-term training. No statistically significant correlations were identified between relative changes in left ventricular mass and QRS voltages.
An early period of intensive physical training in young athletes is associated with a decrease in QRS amplitude and a relative voltage deficit over the left ventricle.
Radamés M.V. Medeiros, Eduardo S. Alves, Valdir A. Lemos, Paulo A. Schwingel, Andressa da Silva, Roberto Vital, Alexandre S. Vieira, Murilo M. Barreto, Edilson A. Rocha, Sergio Tufik and Marco T. de Mello
Body-composition assessments of high-performance athletes are very important for identifying physical performance potential. Although the relationship between the kinanthropometric characteristics and performance abilities of Olympic swimmers is extremely important, this subject is not completely understood for Paralympic swimmers.
To investigate the relationship between body composition and sport performance in Brazilian Paralympic swimmers 6 mo after training.
Experimental pre/posttest design.
Research laboratory and field evaluations of swimming were conducted to verify the 50-m freestyle time of each athlete.
17 Brazilian Paralympic swim team athletes (12 men, 5 women).
Main Outcome Measures:
Body-composition assessments were performed using a BOD POD, and swimming performance was assessed using the 50-m freestyle, which was performed twice: before and after 6 mo of training.
Increased lean mass and significantly reduced relative fat mass and swimming time (P < .05) were observed 6 mo after training. Furthermore, a positive correlation between body-fat percentage and performance (r = .66, P < .05) was observed, but there was no significant correlation between body density and performance (r = –.14, P > .05).
After a 6-mo training period, Paralympic swimmers presented reduced fat mass and increased lean body mass associated with performance, as measured by 50-m freestyle time. These data suggest that reduced fat-mass percentage was significantly correlated with improved swimming performance in Paralympic athletes.
Janne Sallinen, Arto Pakarinen, Mikael Fogelholm, Elina Sillanpää, Markku Alen, Jeff S. Volek, William J. Kraemer and Keijo Häkkinen
This study examined the effects of strength training and diet on serum basal hormone concentrations and muscle mass in aging women. Fifty-one women age 49 to 74 y were divided into two groups: strength training and nutritional counseling (n = 25), and strength training (n = 26). Both groups performed strength training twice a week for 21 wk. Nutritional counseling was given to attain sufficient energy and protein intake and recommended intake of fat and fiber. We found that the cross-sectional area of the quadriceps femoris increased by 9.5 ± 4.1% in the nutritional counseling group versus 6.8 ± 3.5% in the strength training only group after training (P < 0.052). Nutritional counseling evoked dietary changes such as increases in the proportion of energy from protein and the ratio of poly-unsaturated and saturated fatty acids. Strength training increased testosterone and testosterone/sex hormone-binding globulin ratio after the first half of training, but these returned to baseline values at the end of the entire training period. Changes in serum basal hormone concentrations did not differ between the groups. Our results support the conclusion that nutritional counseling can contribute to the increase in the muscle cross-sectional area during prolonged strength training in aging women.
Crayton L. Moss and Scott Grimmer
The purpose of this study was to determine whether twitch contractile properties and strength of the triceps surae could be altered by 8 weeks of low-repetition or high-repetition isotonic exercise. Subjects were randomly assigned to either the low- or high-repetition group. Before- and after-training measurements were recorded for strength and contractile properties. The contractile variables of the muscle twitch were latency, time to peak force, peak force, half-contraction time, and half-relaxation time. Strength measurements were determined utilizing a one repetition maximal (1-RM) heel-raise testing device. A two-way ANOVA with repeated measures was used to test the effect of training on each variable. Both groups showed a significant increase in 1-RM and half-relaxation time and a decrease in electrical stimulation current after the 8-week training period. It was concluded that if high-repetition exercises develop slow-twitch Type I muscle fibers and low-repetition exercises develop fast-twitch Type II fibers, training programs must be designed specifically according to the desired outcome.