Kosuke Kojima

Whole body muscle hypertrophy from resistance training: distribution and total mass.

Objective: To examine the absolute and relative changes in skeletal muscle (SM) size using whole body magnetic resonance imaging (MRI) in response to heavy resistance training (RT). Method: Three young men trained three days a week for 16 weeks. Results: MRI measured total SM mass and fat free mass (FFM) had increased by 4.2 kg and 2.6 kg respectively after resistance training. Conclusions: RT induces larger increases in SM mass than in FFM. RT induced muscle hypertrophy does not occur uniformly throughout each individual muscle or region of the body. Therefore the distribution of muscle hypertrophy and total SM mass are important for evaluating the effects of total body RT on muscle size.

In-Water Resisted Swim Training for Age-Group Swimmers: An Evaluation of Training Effects

PURPOSE The purpose of this study is to compare the efficacy of resisted sprint swim training with that of nonresisted sprint swim training on 50-m freestyle competition time (Vmax50) in age-group swimmers. METHODS Twenty-four age-group swimmers (age 10.6-14.9 y) were divided into resisted or nonresisted sprint swim training groups and completed a sprint swim training intervention 2 times per week for 10 weeks. Repeated 10-m sprints with progressively increasing resistance were used to determine measures of swim power. Skeletal muscle mass was estimated using B-mode ultrasound. Maturity status was estimated using predicted adult height (%Htadult) and maturity offset. RESULTS A 2-way repeated-measures analysis of variance revealed no group × time interaction for measured variables. Vmax50 was correlated with skeletal muscle mass and swim power variables, but no significant relationship was found between relative changes in these variables. Estimated maturity status (%Htadult) appeared to be associated with initial measures of swim power and performance variables. CONCLUSIONS Ten weeks of resisted sprint swim training was not any more effective than nonresisted sprint swim training at improving sprint swim performance in age-group swimmers.

Total and Segmental Subcutaneous Adipose Tissue Volume Measured by Ultrasound in Men and Women

Total and segmental subcutaneous adipose tissue volumes (SATV) were estimated and compared in 13 healthy young women with a mean age of 21.4 yr. Total and segmental (head and neck, forearm, upper arm, trunk, thigh, and lower leg) SATV were estimated from subcutaneous adipose tissue layer thickness and the body surface area; the former by B-mode ultrasound and the latter by direct measurement. Consecutive magnetic resonance images (MRI) were obtained from head to toe (10 mm thickness), from which adipose tissue areas as well as total and regional SATV were determined. SATV of the upper arm and thigh estimated by ultrasound was significantly lower compared to that of MRI-measured SATV; however, there were no significant differences found in the other four segments. As a result, total estimated SATV obtained was on average 5.5% lower with ultrasound than with MRI-measured total SATV; however, there were no statistically significant differences between the two values. Significant strong correlations were observed between MRI-measured total and segmental SATV, and SATV estimated by ultrasound (r = 0.79-0.95) for all segments except head and neck. These results show the effectiveness of the ultrasound method for estimating SATV; however, the quantitative analysis tissue volumes would require correction.