Prevalence of sarcopenia and impact of resistive exercise in a fully independent elderly population

Sarcopenia, the age-associated loss of muscle mass (Narici&Maffulli, 2010) is a main determinant of functional impairment and physical disability in old age. However, the prevalence of sarcopenia amongst fully independent individuals and its reversibility in response to resistive training (RT) are scarcely known. Hence, this study aimed at establishing (i) the prevalence of sarcopenia in fully independent older individuals and (ii) the efficacy of a 12-week RT programme in reversing sarcopenia and its associated muscle weakness. METHODS 26 participants (14 men and 12 women), aged 65-83 yrs, were recruited for this study and underwent 12-week of RT, (3 times/week, 3 sets,14-16 reps), on a leg press machine. Pre- and post-training measurements included: Skeletal Muscle Index (SMI, by bioelectrical impedance); Gait speed (GS) over 4 m; Stair climbing power (SCP); Muscle Architecure of vastus lateralis muscle (pennation angle (Ɵ) and muscle thickness (MT) measured by ultrasonography); 1RM on the leg press. Data were analyzed with descriptive statistics and paired Student’s t-test. RESULTS Before training the prevalence of type I sarcopenia was 61.5% and of type II was 38.5% (classified according to Janssen, 2002). Considering the changes in functional performance, 77% participants (20/26) were responders, while 23% of the participants were non-responders (6 out of 26). For the responders, SMI increased by 2.5% (29.5±4.7 vs 30.3±4.5 %, p<0.001), GS by 5.2% (1.32±0.2 vs 1.39±0.2 ms-1, n.s.), SCP by 7.7% (300.3±111.2 vs 321.8±144.5 W, p=0.04), Ɵ by 8.5% (13.8±3.7 vs 14.9±3.3 deg, p=0.03), MT by 3.5% (1.72±0.4 vs 1.78±0.4 cm, n.s.). 1RM increased by 69% (89.2±59.2 vs 150.8±69.0 kg, p<0.001). 2 participants moved from class II to I sarcopenia and 5 participants from I to a normal SMI . CONCLUSIONS The present findings show that sarcopenia affects >50% of a population of fully independent older individuals (65+ yrs), and that significant improvements in muscle mass, strength are afforded by resistive training. It is noteworthy that these structural and functional gains are associated with a net improvement in key activities of daily living such as stair climbing.