PURPOSE: Muscle power declines with age and disease and predicts functional impairment. Although effective in some other cohorts, the benefits of high intensity, high velocity progressive resistance training (power training) on muscle strength, power, contraction velocity and lower limb function in older adults with type 2 diabetes has not been investigated.
METHODS: 103 overweight/obese older adults (>60 years) were randomized to receive high intensity power training [80% peak strength (1RM)] or sham-exercise, 3 days per week for 1 year. Peak muscle power, peak contraction velocity and 1RM were measured on Keiser knee extension (KE) and chest press (CP) machines before and after the intervention. Lower limb function was assessed using habitual and maximal gait speed, repeated chair stand and stair climb power.
RESULTS: KE and CP 1RMs significantly increased following power training compared to sham-exercise [mean difference (CI) = 28.97 (5.17, 52.77) Nm and 75.99 (40.25, 111.74) N respectively]. Similar results were observed for KE and CP peak power [(mean difference = 75.83 (35.82, 115.84) W and 26.77 (6.30, 47.24) W, respectively]. No effects were observed for changes in contraction velocity for KE or CP (p<0.05). Both groups showed similar improvements in habitual and maximal gait speed and chair stand time (p<0.05). Increases in KE peak power were explained by increases in KE 1RM (r=0.32, p=0.003), but not changes in KE contraction velocity (r=0.12, p=0.26). In contrast, increases in CP peak power were explained by increases in CP contraction velocity (r=0.52, p<0.001) but not increases in CP 1RM (r=0.17, p=0.26). Neither changes in KE 1RM nor peak power were associated with changes in lower limb function.
CONCLUSIONS: 1 year of power training significantly improved upper and lower body strength and power in older adults with type 2 diabetes. Improvements in lower limb power were associated with increases in strength but not contraction velocity. Conversely, improvements in upper limb power were associated with increases in contraction velocity but not strength. Unexpectedly, improvements in lower extremity function were not associated with changes in lower leg strength or power, suggesting that unaddressed factors such as obesity may have attenuated the benefits of power training on functional performance.