The aim of this study was to determine whether elderly and young adults with similar physical activity levels have similar soleus H-wave maximum/M-wave maximum ratios (H-reflex size) and to determine the relationship between H-reflex size and physical activity level. H-reflex size and physical activity levels were measured in 18 elderly (71 ± 5.7 years) and 20 young (24 ± 4.2) participants. The physical activity levels of the 2 groups were not significantly different. The elderly group had smaller H-rellexes than the young group (elderly. 36% ± 27%; young, 59% ± 17%; p < .05), but the effect of age on H-reflex size was only moderate (omega squared = .19, effect size = .30). There was a weak tendency for higher levels of physical activity to be associated with larger H reflexes (r = .38, p < .05). The findings indicate that soleus H-reflex size is not strongly associated with age or physical activity level.