Updated guidelines find even small amounts of resistance training build muscle

The first major update to resistance-training guidelines in 17 years delivers one clear message: any amount of resistance training improves strength, muscle size, power and physical function.

The new recommendations, published in Medicine & Science in Sports & Exercise by the American College of Sports Medicine (ACSM) as a Position Stand, are based on 137 systematic reviews involving more than 30,000 participants, making them the most comprehensive resistance-training guidelines to date.

“The best resistance training program is the one you’ll actually stick with,” says Stuart Phillips, distinguished professor in the Department of Kinesiology and an author on the Position Stand. “Training all major muscle groups at least twice a week matters far more than chasing the idea of a ‘perfect’ or complex training plan. Whether it’s barbells, bands, or bodyweight, consistency and effort drive results.”

This update has been a long time coming. ACSM last published a Position Stand on resistance training for healthy adults in 2009, predating the explosion of research on muscle health, aging and the role of strength in long-term well-being.

“The new document reflects that surge in evidence and expands its recommendations to include more people and more types of training than ever before,” Phillips says.

A central theme of the new Position Stand is that the most meaningful gains come from a simple shift: moving from no resistance training to any form of it. While training variables such as load, volume, or frequency can be fine-tuned, the primary goal for most adults should be to build a consistent routine.

One of the greatest changes is the recognition that meaningful results don’t require a gym. Elastic bands, bodyweight training and home-based routines offer clear and measurable improvements in strength, muscle size and functional performance.

Rigid rules and prescriptive ideal programs are no longer supported by evidence, explains Phillips. Instead, personal goals, enjoyment, and long-term adherence matter most, especially for adults looking to stay strong, healthy and functional as they age.

Athletes and highly trained individuals will still require more specialized, sport-specific programs, but for the average adult, the message is simple: find a resistance-training routine you enjoy and stick with it.