ABSTRACT
To determine the influence of age and resistance exercise on myostatin pathway-related genes, younger (n = 10; 28 ± 5 years) and older (n = 10; 68 ± 6 years) men underwent four testing conditions (T1-T4). A baseline (T1) muscle sample was obtained, whereas the second and third biopsies were obtained 48 hours following the first and second training sessions (T2, T3), and a final biopsy was taken 24 hours following T3. The training sessions consisted of 3 sets of 10 repetitions (80% of one repetition maximum) on leg press, hack squat, and leg extension exercises. Follistatin (FST) messenger RNA was greater in older compared with younger men at T1 and T2 (p < .05). Follistatin-like 3 (FSTL3) messenger RNA was greater in older compared with younger men at T1 and T4 (p < .05). In older men, there was a significant decrease in myostatin (MSTN) messenger RNA at T4 (p < .05). Older men contained less active (Ser-425 phosphorylated) SMAD3 (p-SMAD3) protein than younger men at T3 and T4 (p < .05).Although it is well known that younger individuals possess a greater hypertrophic potential to resistance exercise, it appears that older individuals may paradoxically possess a more favorable resistance exercise response regarding myostatin pathway-related genes and a protein marker of pathway activity. Future research is warranted to examine the physiological significance of this age-dependent mechanism.
