The American College of Sports Medicine (ACSM) has published an updated position stand summarizing the latest evidence on resistance training (RT) prescriptions for healthy adults. This overview of 137 systematic reviews, encompassing over 30,000 participants, evaluates how different RT variables influence muscle strength, hypertrophy, power, endurance, contraction velocity, and physical performance.
Resistance training, which involves exercising muscles against external resistance such as weights or bands, is recognized for its broad health benefits including improved muscular function, reduced risk of chronic diseases, and enhanced mental well-being. Despite these benefits, participation rates remain low, with only about 30% of American adults engaging in muscle-strengthening activities twice weekly.
The updated guidance confirms that RT significantly improves muscle strength, size, power, endurance, balance, gait speed, and other functional outcomes compared to no exercise. Various forms of RT—including standard weightlifting, elastic band training, home-based programs, circuit training, and velocity-based training—demonstrate effectiveness.
Key findings highlight that muscle strength gains are optimized by lifting heavier loads (at least 80% of one-repetition maximum), performing exercises through a full range of motion, completing 2–3 sets per exercise, and training at least twice per week. Muscle hypertrophy benefits from higher training volumes (10 or more sets per week) and eccentric overload techniques. Power improvements are best achieved with moderate loads (30%–70% one-repetition maximum), lower volumes, and power-focused training methods such as Olympic-style lifts and fast concentric movements.
Interestingly, some commonly considered variables—such as training to failure, equipment type, exercise complexity, set structure, time under tension, blood flow restriction, and periodization—did not consistently influence outcomes across studies.
The ACSM emphasizes the principle of progressive overload, where training stimulus is gradually increased to continue adaptations, but notes that progression is not strictly necessary for initial benefits. Individualization of programs to suit personal goals, preferences, and experience levels is encouraged to enhance adherence and safety.
The review also addresses safety concerns, affirming that resistance training is generally safe for healthy adults of all ages, with low risk of serious adverse events when properly supervised.
This comprehensive synthesis updates the 2009 ACSM Position Stand by incorporating a much larger evidence base and modern evidence grading methods. It provides practitioners and individuals with clearer, evidence-based recommendations to design effective resistance training programs that improve muscle function and physical performance. Given the low participation rates in RT, the ACSM underscores the importance of promoting accessible and varied RT approaches to support public health.