VASTUS LATERALIS HYPERTROPHY EXCEEDS WEIGHT AND HEIGHT INCREASES FOLLOWING SUMMER TRAINING PROGRAM IN PREADOLESCENT BOYS
Jonathan D. Miller1, Mandy E. Wray1, Hannah L. Dimmick1, and Trent J. Herda1
1University of Kansas, Lawrence, KS
It is well documented that preadolescent children gain unhealthy body mass during the summer months which is largely attributed to physical inactivity. PURPOSE: To analyze changes in vastus lateralis (VL) muscle cross-sectional area (mCSA) and composition via ultrasonography in relation to growth in height and body mass following an 8-week summer training program for children ages 5-11 years old. METHODS: Nine boys (age=8.2±2.1 years, height=135.1±10.5 cm, body mass=35.7±7.3 kg, BMI range=15.7‒34.5 kg/m2) completed 2, 50-minute training sessions per week for 8 weeks. The training sessions consisted of functional high intensity upper and lower body resistance exercises as well as anaerobic sprint and agility drills. Height, body mass, and ultrasound measurements were collected prior to- and following the training program. Cross-sectional ultrasound scans were taken at 50% of the distance from the anterior superior iliac spine to the superior border of the patella. Subcutaneous fat above the muscle was measured from the bottom of the cutaneous layer to the superficial fascia above the muscle. The borders of the VL were carefully outlined and this cross-sectional area was considered mCSA, while the mean greyscale of the area was considered the muscle echo intensity (mEI). RESULTS: Paired samples t-tests indicated following the 8-week training program there no significant changes in body mass (P=0.242), mEI (P=0.562), or subcutaneous fat (P=0.327). However, there was a significant 0.98% increase in height (P=0.001), and a significant 7.6% increase in mCSA (P=0.002) from pre- to post-training. CONCLUSIONS: The 8-week training program was effective to limit increases in body mass and subcutaneous fat as well as intramuscular fat (as measured by mEI) while increasing VL mCSA. In addition, the 7.6% increase in mCSA is likely not due to normal growth alone as the increase in height (0.98%) and the nonsignificant increase in body mass (1.8%) were proportionally smaller.
Miller, JD; Wray, ME; Dimmick, HL; and Herda, TJ
"VASTUS LATERALIS HYPERTROPHY EXCEEDS WEIGHT AND HEIGHT INCREASES FOLLOWING SUMMER TRAINING PROGRAM IN PREADOLESCENT BOYS,"
International Journal of Exercise Science: Conference Proceedings: Vol. 11:
6, Article 49.
Available at: https://digitalcommons.wku.edu/ijesab/vol11/iss6/49