Although master athletes maintain high levels of physical activity, they also suffer from an age-related decline in skeletal muscle function. There are indications of disproportional age- and physical inactivity-induced muscle wasting between muscles. Tensiomyography is a noninvasive tool that has been used to study the effects of a variety of sports on the contraction time (Tc) in different skeletal muscles. The aim of this cross-sectional study was to assess age-related changes in the Tc of the vastus lateralis, gastrocnemius medialis, and biceps femoris muscles with Tensiomyography in older nonathletes (age = 62.1 ± 12.7 years; NMALES = 133; NFEMALES = 246), and power (age = 56.9 ± 13.5 years; NMALES = 100; NFEMALES = 78) and endurance master athletes (age = 56.5 ± 14.5 years; NMALES = 76; NFEMALES = 73). We found an age-related slowing in all muscles, irrespective of discipline, where endurance master athletes had the longest and power master athletes had the shortest Tc. The longer Tc in endurance master athletes than in nonathletes suggests that regular endurance sport activity aggravates slowing of skeletal muscles during aging.