The Impact of Resistance Training Program on the Muscle Strength and Bone Density in Adolescent Athletes

Strength training and other modes of physical activity may be beneficial in osteoporosis prevention by maximizing bone mineral accrual in childhood and adolescence. This study focuses on the impact of the nine-month long program of resistant exercises with different level of external loads (low, middle and high) on the lower limbs explosive strength and bone tissue density in athletes adolescents aged 17 to 18 years. Sixty healthy, male athletes and non-athletes, divided into experimental (ES, sprinters, N = 45) and control sub-sample (CS, non-athletes, N = 15), were included in study. ES examinees (EG1, EG2 and EG3) were subjected to the program of resistance exercises with low level (60% of the One Repetition Maximum-1RM), middle level (70% 1RM), and high level (85% 1RM) of external loads, respectively. Bone Density values were determined by the use of a clinical sonometer „Sahara” (Hologic, Inc., MA 02154, USA). Explosive strength values of hip extensors and flexors, knee extensors and flexors, and ankle plantar and dorsiflexors were determined by the use of accelerometer „Myotest” (Sion, Switzerland) and the means of Counter Movement Jump without arms swing (CMJ) and half squat. ANOVA method for repeated measures and ANCOVA method were used to determine significant differences and resistance program effects on the lower limbs explosive strength and bone tissue density. Resistance exercise does impact the explosive strength and bone parameters in a way to increase half squat 1RM values, but decreases CMJ values, and increases speed of sound (SOS), broadband ultrasound attenuation (BUA) and bone mineral density (BMD) values in athletes-adolescents, aged 17-18 years.