Unlocking the barriers to improved functional capacity in the elderly: rationale and design for the "Fit for Life trial".

Advancing age is associated with an increase in physical impairment, functional limitations, disability, and loss of independence. Regular physical activity conveys health benefits, but the yield on physical function in the elderly, is less clear. Current exercise guidelines are focused predominantly on aerobic programs despite evidence that age-associated declines are mediated by peripheral tissue changes. The Fit for Life trial proposes a new paradigm of exercise training for the elderly that uses a low-mass high-repetition training regimen specifically focused on peripheral tissue beds or body regions (Regional Specific Training Stimulus - RSTS). RSTS is designed to deliver a localized stimulus to the peripheral vasculature, bone and muscle, without imposing a significant central cardiorespiratory strain. The purpose of this study is three-fold; 1) to derive effect sizes from the RSTS intervention by which to power a subsequent larger, confirmatory trial; 2) to assess fidelity of the RSTS intervention; and 3) to assess the interrelationship of the primary endpoints of physical impairment/fitness (VO(2peak), 1 repetition maximal contraction) and function (Senior Fitness Test scores) following two versions of a 4 + 8 week protocol. Men and women over 70 years, at risk for losing independence will be randomized to either 4 weeks of RSTS or "aerobic" exercise, followed by an identical 8 weeks of progressive whole-body training (aerobic plus resistance). The guiding hypothesis is that the magnitude of adaptation after 12 weeks will be greatest in those initially randomized to RSTS. Possible mediators of the intervention effect - physical impairment/fitness and function relationship, including vascular function, muscle mass, strength, and physiology will also be assessed.