PRIME: A Novel Low-Mass, High-Repetition Approach to Improve Function in Older Adults

The ability to maintain functional independence in a rapidly aging population results in an increased life expectancy without corresponding increases in health care costs. The accelerated decline in V˙O2peak after the age of 65 yr is primarily due to peripheral tissue changes rather than centrally mediated factors. The purpose of this study was to determine whether the Peripheral Remodeling through Intermittent Muscular Exercise (PRIME) approach, consisting of a low-mass, high-repetition/duration skeletal muscle focused training regimen would provide superior functional benefits in participants older than 70 yr old and at risk for losing functional independence.

In this clinical trial, 107 participants were randomized to 4 wk of either standard aerobic training (AT) or PRIME (phase 1). This was followed by 8 wk of a progressive whole-body aerobic and resistance training (AT + RT) for all participants (phase 2). The major outcome measures were cardiorespiratory fitness (peak oxygen consumption [V˙O2peak]), muscular fitness (1 repetition maximal strength [1RM]), and physical function (Senior Fitness Test [SFT] scores). Results were analyzed under a per-protocol criterion.

Thirty-eight PRIME and 38 AT participants completed the 3-month protocols. V˙O2peak, 1RM, and SFT scores all increased significantly after 12 wk for both treatment groups (P < 0.05). However, relative to AT, participants randomized to PRIME demonstrated a greater increase in V˙O2peak (2.37 + 1.83 vs 1.50 + 1.82 mL·kg·min, P < 0.05), 1RM (48.52 + 27.03 vs 28.01 + 26.15 kg, P < 0.01) and SFT (22.50 + 9.98 vs 18.66 + 9.60 percentile, P < 0.05).

Participants experienced greater increases in cardiorespiratory and muscular fitness and physical function when PRIME training was initiated before a combined AT + RT program. This novel exercise approach may be advantageous to individuals with other chronic disease conditions characterized by low functional capacity.