What the first resistance training guidelines update in 17 years means for you

The American College of Sports Medicine just released its first update to resistance training guidelines in 17 years. Built on 137 systematic reviews covering more than 30,000 participants, it is the most comprehensive look at strength training science ever published.

The headline finding is straightforward: even small amounts of resistance training can improve strength, build muscle, and support overall physical function. And the biggest gains tend to come from the simplest starting point.

We spoke with two leading trainers about what the updated guidelines mean and how to actually put them into practice.

The biggest leap was in going from nothing to something

The most striking finding wasn’t about workout intensity. It came much earlier than that—at the starting line. Across the research, the transition from no resistance training to any regular activity produced the most significant gains in strength, muscle size, and physical function.

Waz Ashayer, NASM-certified trainer and creator of P90X Generation Next, has seen this play out at every level. “The biggest transformation always comes from inactive to consistent, not from chasing the perfect program,” he says. “Early on, adherence beats optimization every time. Once someone builds momentum and discipline, then the finer details start to matter.”

Lauren Kleban, celebrity trainer and founder of LEKFIT, agrees—with one important caveat. “For beginners, just getting moving and being consistent is the most important thing. That said, low-impact movement alone may not be enough for those looking to keep building strength over time. Adding structured resistance training is what drives continued progress.”

Equipment is not the barrier

One of the more practical updates in the ACSM guidelines was the formal recognition that resistance training does not require a gym or fancy machinery. Free weights, machines, resistance bands, and even bodyweight movements all produced measurable gains in strength and muscle size across the research.

Ashayer is direct on this point. “Limited equipment is never the limitation. Lack of intent is,” he says.

In many cases, constraints like limited space or equipment can actually force better movement quality and creativity. Worth sitting with for anyone who has spent more time planning the perfect setup or obsessing over the details.

Twice a week is enough to see real results

The updated guidelines confirm that training major muscle groups at least twice a week is sufficient for most adults to see meaningful improvements. For many people, that reframes what a committed routine actually needs to look like.

Ashayer’s approach to a limited-time week is built around efficiency. “Two to three full-body sessions per week, hitting all major movement patterns, is more than enough if the intensity is there. I often combine strength with conditioning to maximize output in minimal time. The goal is to make every session count rather than trying to do everything.”

Consistency matters more than any other variable

The ACSM’s updated guidelines don’t ask you to train harder, which is a common assumption when it comes to making progress in strength and fitness. Once a routine is in place, the research is clear: showing up regularly outperforms any specific program design.

Training to failure was not required. Neither was a structured split. What drove results, across all programs and all participant types, was consistency over time.

Kleban puts it plainly. “If you hate what you’re doing but think it’s good for you, you’re not going to want to work out at all. It’s not going to last and you’ll end up falling into that stop-start, vicious yo-yo cycle.”

Her advice is to find something that feels worth your time, fits your schedule, and then makes showing up non-negotiable. “Just start somewhere and be curious. When you enjoy it and see that it works, consistency becomes much easier.”