Long-term impact of strength training on muscle strength characteristics in older adults

摘要

Objective: To evaluate the long-term preventive impact of strength training on muscle performance in older adults. Design: A 7-year follow-up on a 1-year randomized controlled trial comparing the effects of combined resistance training and aerobic training and whole-body vibration training on muscle performance. Setting: University training center. Participants: Men and women (N=83; control [CON] group, n=27; strength-training intervention [INT] group, n=56) between 60 and 80 years of age. Interventions: The INT group exercised 3 times weekly during 1 year, performing a combined resistance training and aerobic training program or a whole-body vibration training program. The former training program was designed according to American College of Sports Medicine guidelines. The whole-body vibration training program included unloaded static and dynamic leg exercises on a vibration platform. The CON group did not participate in any training program. Main Outcome Measures: Static strength (STAT), dynamic strength at 60 /s (DYN60) and at 240 /s (DYN 240), speed of movement at 20% (S20). Results: From baseline to postintervention, muscle performance did not change in the CON group, except for S20 (+6.55%±2.88%, P.001). One year of strength training increased (P≤.001) STAT (+11.46%±1.86%), DYN 60 (+6.96%±1.65%), DYN240 (+9.25%±1.68%), and S20 (+7.73%±2.19%) in the INT group. Between baseline and follow-up, muscle performance decreased (P.001) in both groups. However, STAT and DYN60 showed a significantly lower loss in the INT group (-8.65%±2.35% and -7.10%±2.38%, respectively) compared with the CON group (-16.47%±2.69% and -15.08%±2.27%, respectively). This positive impact might be due to the preservation of the training-induced gains, given the similar annual decline rates in both groups from postintervention to follow-up. Additionally, in trained participants, aging seems to impact velocity-dependent strength and power more compared with basic strength, as the total losses in DYN240 (CON, -15.93%±2.64%; INT, -11.39%±1.95%) and S20 (CON, -14.39%±2.10%; INT, -13.16%±1.72%) did not differ significantly between the groups. Conclusions: A 1-year strength-training intervention results in an improved muscle performance in older adults 7 years after their enrollment in the intervention. However, an extensive exercise program cannot attenuate the age-related decline once the intervention stops.