Strength Training as an Intervention against the Musculoskeletal Side Effects of Prostate Cancer Treatment

Abstract

Androgen deprivation therapy (ADT) is effective for slowing tumor growth in prostate cancer (PCa) patients, but results in fatigue and a reduction in muscle power, strength, and functional abilities. Black men have the highest incidence and mortality rates of PCa compared to any other racial or ethnic group, yet they are under represented in previous PCa and exercise studies. Strength training (ST) has been used previously in PCa patients to attenuate some of the side effects of ADT, however, it is unclear whether ADT prevents ST-induced gains in muscle power, a strong predictor of physical function. PURPOSE: To determine the effects of ST on muscle power, strength, fatigue resistance and physical function in black men on ADT for PCa. METHODS: 16 black men (age 58-80) with PCa on ADT were assessed at baseline for upper and lower body strength (1RM). Fatigue resistance was determined by the number of repetitions performed during the chest and leg press at 70% of 1RM before fatigue ensued. Knee extensor peak power was measured as the highest power reached at 50, 60, and 70% of 1 RM. Physical function was estimated using 3 separate walking tests, a stair climb test, and the number of chair stands completed in 30 sec. All assessments were repeated after a 12 wk full-body ST program. Changes with ST were determined using paired T-tests. Associations between improvements in muscle function (strength, power, and fatigue resistance) and physical function were analyzed via a correlation matrix. RESULTS: Knee extensor, chest, and leg press 1RM increased significantly (range 14.5 - 23.8%; all P < 0.01), as did chest and leg press endurance (65% and 149% respectively; all P < 0.001) with ST. All indices of physical function also improved significantly with ST (range 6.5 - 17.4%; all P < 0.05). Peak power significantly increased at all intensities for the right leg and at 50 and 60% for the left leg (range 8.4 - 16.5%, P < 0.05). The strongest correlations were between the changes in power and those in the 6m rapid walk (r = 0.55 - 0.70; P < 0.05). CONCLUSIONS: Despite ablation of testosterone from ADT, ST increases muscle power, strength, fatigue resistance, and physical function in black men on ADT. ST-induced improvements in muscle function are associated with faster walking times in these patients. Supported by NIH grants R21CA127784 and AG000268.