Heterogeneity of physical function responses to exercise training in older adults.

Objectives: To describe the interindividual variability in physical function responses to supervised resistance and aerobic exercise training interventions in older adults.

Design: Data analysis of two randomized, controlled exercise trials.

Setting: Community-based research centers.

Participants: Overweight and obese (body mass index (BMI)≥27.0 kg/m2) sedentary men and women aged 65 to 79 (N=95).

Intervention: Five months of 4 d/wk of aerobic training (AT, n=40) or 3 d/wk of resistance training (RT, n=55).

Measurements: Physical function assessments: global measure of lower extremity function (Short Physical Performance Battery (SPPB)), 400-m walk, peak aerobic capacity (VO2 peak), and knee extensor strength.

Results: On average, both exercise interventions significantly improved physical function. For AT, there was a 7.9% increase in VO2 peak; individual absolute increases varied from 0.4 to 4.3 mL/kg per minute, and four participants (13%) showed no change or a decrease in VO2 peak. For RT, knee extensor strength improved an average of 8.1%; individual increases varied from 1.2 to 63.7 Nm, and 16 participants (30%) showed no change or a decrease in strength. Usual gait speed, 400-m walk time, chair rise time, and SPPB improved for the majority of AT participants and usual gait speed, chair rise time, and SPPB improved for the majority of RT participants, but there was wide variation in the magnitude of improvement. Only change in 400-m walk time with RT was related to exercise adherence (correlation coefficient=-0.31, P=.004).

Conclusion: Despite sufficient levels of adherence to both exercise interventions, some participants did not improve function, and the magnitude of improvement varied widely. Additional research is needed to identify factors that optimize responsiveness to exercise to maximize its functional benefits in older adults.