The ACSM just updated its resistance training guidelines for the first time in 17 years - here's what it means for you

by Rosie Stockley · Strong for Life

In April 2026, the American College of Sports Medicine updated its resistance training guidelines for the first time since 2009 - seventeen years - and the headline finding is one I want you to sit with. Training all your major muscle groups twice a week is enough to drive meaningful results across all the markers that matter for long-term health: muscular strength, lean muscle mass, bone density, and metabolic function.

I've been sharing this with the women I train with, and the response is almost always the same - a kind of cautious disbelief, followed by "but surely that's not enough?" I understand that completely, because most of us have absorbed a very different message about what commitment looks like in the gym. So I want to break this down properly: what the guidelines actually say, why twice a week works, and why this matters so much if you're training in your 40s or going through perimenopause.

What the updated ACSM guidelines say

The American College of Sports Medicine (https://www.acsm.org/education-resources/trending-topics-resources/physical-activity-guidelines) is one of the most respected bodies in exercise science globally, and their guidelines are based on large bodies of evidence - systematic reviews, meta-analyses, longitudinal studies - rather than trends or preferences.

The updated position stand confirms that for most adults, performing resistance training that targets all major muscle groups (legs, back, chest, shoulders, arms, core) two days per week is sufficient to produce meaningful gains in muscular strength and endurance, lean muscle mass, bone mineral density, metabolic function and insulin sensitivity, and cardiovascular health markers.

Three or more sessions a week can produce additional benefit in some people, particularly those training for performance or sport. But for general health, longevity, and body composition, two quality sessions a week is a legitimate, research-backed programme - not the beginner option, not the bare minimum, but a proper evidence-supported approach.

Why twice a week is enough: the science

This might feel counterintuitive if you've spent years believing that more always equals better, so it's worth understanding the mechanism.

When you resistance train, you create small amounts of stress in the muscle fibres. The body responds by repairing and rebuilding those fibres, making them slightly stronger and more resilient in the process. This process - called muscle protein synthesis (https://pubmed.ncbi.nlm.nih.gov/23551944/) - takes time. After a training session, elevated muscle protein synthesis typically lasts around 24 to 48 hours in younger adults, and often longer as we age, and that repair window is where the adaptation happens.

Training a muscle before it has fully recovered doesn't accelerate progress - it can interfere with it, because you're adding new stress before the adaptation from the last session is complete. A 2016 meta-analysis published in Sports Medicine (https://pubmed.ncbi.nlm.nih.gov/27102172/) by Schoenfeld and colleagues found that training each muscle group twice per week was superior to once a week for hypertrophy, but that three times a week showed only marginal additional benefit over two in most people. The sweet spot for most of us is hitting each muscle group twice, with adequate recovery between sessions.

It's also worth noting that consistency compounds. Two sessions a week done reliably over years produces far better results than five sessions a week done inconsistently, or an approach so demanding it leads to burnout or injury.

Why this matters particularly if you're in perimenopause

For women training through perimenopause and beyond, the updated guidelines are especially significant, because the temptation to do more when you're not seeing the results you expect is very real - and often counterproductive.

As oestrogen fluctuates and declines, recovery takes longer. Oestrogen plays an active role in muscle repair (https://pubmed.ncbi.nlm.nih.gov/24950190/), so processes that used to happen in 24 hours may now need 36 to 48. Inflammation after exercise can run higher and take longer to resolve. Sleep, where a significant amount of the adaptation from training occurs, is often disrupted during this phase too.

More training sessions don't just offer diminishing returns for women in perimenopause - they can work against you, by compressing the recovery window your body needs, adding physiological stress that disrupts sleep further, and elevating cortisol in ways that make body composition harder to shift rather than easier. Two well-structured sessions a week, with recovery built around them, is not a concession. For many women at this life stage, it is the most intelligent approach.

There is also strong evidence connecting resistance training with bone health in perimenopausal and postmenopausal women. A review published in Osteoporosis International (https://pubmed.ncbi.nlm.nih.gov/22006241/) found that progressive resistance training is one of the most effective interventions for maintaining and improving bone mineral density, and that two sessions per week was sufficient to produce measurable bone-protective effects - which matters because bone density loss accelerates significantly in the years around menopause.

What twice a week actually looks like

Two sessions a week works when they're well-structured - a focused 30 to 50 minutes built around compound movements that work multiple muscle groups at once (squats, hinges, rows, presses), with progressive overload over time so the body keeps adapting. The effort level should be challenging for the last few reps of each set, and the weights or difficulty should increase gradually over weeks and months.

This is exactly how Strong for Life is structured - each session built around the major movement patterns, progressing week on week, with recovery factored in as part of the programme rather than an afterthought.

On the "more is more" culture

I want to say something directly about the culture many of us have absorbed around exercise, because I think it's getting in the way for a lot of women.

The idea that training twice a week isn't enough is tied up in a broader message that commitment is measured in hours and sweat, and that anything less than five days a week means you're not really serious. This isn't evidence-based - it's a mindset built around athletic performance that was applied wholesale to general fitness without much scrutiny.

For women in their 40s and 50s, this message is particularly unhelpful. Not because we can't work hard - we absolutely can - but because the demands of this life stage are real. Work, family, perimenopause symptoms, disrupted sleep, stress. Adding a training programme that asks too much on top of all of that often ends in injury or burnout. The ACSM guidelines aren't telling you to do less. They're giving you permission to train in a way that's sustainable, evidence-based, and effective - without the guilt that can come from feeling like you should always be doing more. And what the science is saying, clearly, is that two sessions a week has always been enough.

Ready to train twice a week the right way?

If you want a programme designed around the evidence - two strength sessions a week, structured progressively, built for women in perimenopause and beyond - that's exactly what Strong for Life is. Find out more here: https://strongforlifewithrosie.com

And if you're not quite there yet, my free guide The Midlife Training Reset covers the six key shifts that make training work differently after 40, including why you might need less cardio and more recovery than you think. Download it free here: https://strongforlifewithrosie.com/guide

Rosie x

References:

- ACSM Physical Activity Guidelines - American College of Sports Medicine: https://www.acsm.org/education-resources/trending-topics-resources/physical-activity-guidelines

- Schoenfeld et al. (2016). Effects of Resistance Training Frequency on Measures of Muscle Hypertrophy: A Systematic Review and Meta-Analysis. Sports Medicine. https://pubmed.ncbi.nlm.nih.gov/27102172/

- Churchward-Venne et al. (2013). Nutritional regulation of muscle protein synthesis with resistance exercise. Nutrition & Metabolism. https://pubmed.ncbi.nlm.nih.gov/23551944/

- Greising et al. (2014). Estrogen's role in skeletal muscle repair. PLOS ONE. https://pubmed.ncbi.nlm.nih.gov/24950190/

- Martyn-St James & Carroll (2010). Progressive resistance training and bone mineral density in postmenopausal women. Osteoporosis International. https://pubmed.ncbi.nlm.nih.gov/22006241/