Heterogeneity of Physical Function Responses to Exercise Training in Older Adults

ObjectivesTo describe the interindividual variability in physical function responses to supervised resistance and aerobic exercise training interventions in older adults. DesignData analysis of two randomized, controlled exercise trials. SettingCommunity-based research centers. ParticipantsOverweight and obese (body mass index (BMI) 27.0kg/m(2)) sedentary men and women aged 65 to 79 (N=95). InterventionFive months of 4d/wk of aerobic training (AT, n=40) or 3d/wk of resistance training (RT, n=55). MeasurementsPhysical function assessments: global measure of lower extremity function (Short Physical Performance Battery (SPPB)), 400-m walk, peak aerobic capacity (VO(2)peak), and knee extensor strength. ResultsOn average, both exercise interventions significantly improved physical function. For AT, there was a 7.9% increase in VO(2)peak; individual absolute increases varied from 0.4 to 4.3mL/kg per minute, and four participants (13%) showed no change or a decrease in VO(2)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). ConclusionDespite 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.