Reps in Reserve (RIR) is a way to measure how many more repetitions you could perform at the end of a set before reaching failure. For walking and low-impact exercise, RIR can be a useful tool to gauge effort without overexerting yourself. Since these activities are generally moderate in intensity, using RIR helps maintain a safe level of exertion while still promoting fitness benefits.
In walking or other low-impact exercises, the goal is often to improve cardiovascular health, endurance, and mobility rather than maximal strength or muscle growth. By keeping a few reps in reserve, you avoid pushing to exhaustion, which reduces injury risk and allows for consistent, sustainable training. This approach aligns with recommendations to perform moderate-intensity aerobic activity for at least 150 minutes per week, combined with strength and mobility work done at a manageable effort level[2].
For strength training components that might accompany walking or low-impact routines, such as bodyweight exercises or light resistance work, RIR helps balance effort and recovery. Ending sets with 1 to 3 reps in reserve ensures you are working hard enough to stimulate adaptation but not so hard that fatigue compromises form or recovery[2][7]. This is especially important for those new to exercise, older adults, or individuals with joint concerns, where avoiding excessive fatigue is key.
While RIR is often discussed in the context of heavier strength training for muscle growth or power, its principle of self-regulating effort applies well to low-impact exercise. It encourages listening to your body and adjusting intensity accordingly, which can improve adherence and reduce burnout. For example, in walking, you might aim to finish a session feeling like you could still walk a bit more briskly without strain, reflecting a few reps in reserve in terms of effort.
In summary, RIR is a practical and adaptable concept that helps manage intensity in walking and low-impact exercise. It supports safe progression by preventing overexertion while still encouraging enough effort to gain health and fitness benefits.
Sources
https://www.bodyspec.com/blog/post/fitt_principle_a_guide_to_a_smarter_workout_plan
https://erickimphotography.com/maximum-muscle-growth-the-ultimate-battle-plan/
