The Effects of a Single Bout of Resistance Exercise on Serum Level of Myostatin and Follistatin in Elderly Men

Aging is associated with progressive loss of strength and muscle mass that this process is commonly referred to as “sarcopenia”. Decline in muscle mass and strength related to aging or sarcopenia leads to significant impairment in the ability to carry out normal daily functions and an increased risk of falls and fractures. Muscle hypertrophy is likely to result from the cumulative effects of repeated bouts of resistance exercise on post-exercise molecular responses. Therefore, we determined muscle growth-and regeneration-related factor in response to a single resistance exercise bout in elderly men. Twelve healthy elderly men (age 64.2±3.2 years, weight 76.6±6.5 kg, height 177.5±4.8 cm, fat mass 18.2±2.6 kg, lean body mass 57.2±4.7 kg) volunteered as subjects and performed one bout of lower body resistance exercise consisted of 3 sets of 12 repetitions at 75% 1-RM. Blood samples were obtained at rest and immediately, 4hr and 24hr after resistance exercise bout. Serum levels of myostatin and follistatin were determined by ELISA and Data were analyzed with repeated-measure ANOVA. Serum level of myostatin was significantly decreased (P˂0.05) immediate and 4h after resistance exercise (13.34±4 and 12.68±4.3ng/ml, respectively) compared to pre-exercise (17.22±5.2ng/ml). Conversely, the single resistance exercise bout increased (P˂0.05) serum level of follistatin in 4h and 24h after resistance exercise (13.2±2.4 and 13.09±2.1ng/ml, respectively) compared to pre-exercise (8.79±2.8ng/ml). These results suggested that a resistance exercise in older men by decreased serum level of myostatin and increased serum level of follistatin can prevented of sarcopenia. These changes may reveal the molecular mechanisms involved in the muscle hypertrophy reported in the elderly men after resistance exercise. This is possible eventually caused reduce the incidence of age-related muscle atrophy (sarcopenia) in the elderly. Keyword: Myostatin, Follistatin, Elderly Men, Resistance Exercise INTRODUCTION Aging is related to a gradual loss of skeletal muscle mass, strength, and power, a condition called sarcopenia. Consequently, older people are predisposed to different disabilities, increased incidence of falls, and decreased capacity to perform daily tasks (Bodine et al., 2001). Importantly, in older adults, repeated resistance exercise has well-established beneficial effects on body composition and physical fitness (Borst et al., 2002; Carlson et al., 1999) and on the capacity to perform daily tasks of living (Carlson et al., 1999). These training adaptations are likely to result from the cumulative effects of repeated bouts of resistance exercise on post-exercise molecular responses (Cesari et al., 2008). During the past years, the underlying mechanisms responsible for muscle mass wasting related-aging have been extensively investigated (Carlson et al., 1999; Cesari et al., 2008). One of the hypothetical pathways by which repeated resistance exercise induced short-term molecular responses may eventually lead to muscle hypertrophy involves gene regulation via the myostatin pathway (Craig et al., 2008). Myostatin (also known as growth/differentiation factor-8) is a member of the transforming growth factor-β family that plays an essential role in the regulation of skeletal muscle mass (Gilson et al., 2009; Glass, 2005). Strength training induced muscle hypertrophy involves satellite cell proliferation, differentiation, and fusion with existing myofibers, which is important for the maintenance of adequate nuclear/cytoplasmic ratio during muscle growth (Bodine et al., 2001). Myostatin seems to work in adult muscle in part by Cibtech Journal of Zoology ISSN: 2319–3883 (Online) An Open Access, Online International Journal Available at http://www.cibtech.org/cjz.htm Ramezanpour and di Seye / 26 9 1 December, pp. 2015 Vol. 4 (3) September