Can Stretching Build Muscle? What the Research Really Shows

Most people stretch to improve flexibility. But could stretching also help muscles grow?

Research suggests that sustained static stretching may offer benefits beyond range of motion. Under certain conditions, it can also increase muscle thickness and strength an interesting finding for anyone involved in fitness or assisted stretching.

What Did the Study Involve?

A study published in January 2024 in the European Journal of Applied Physiology compared chest stretching with resistance training over eight weeks.

Tim Wohlann and colleagues allocated 81 recreationally active participants to three groups:

• Static stretching: 15 minutes of chest stretching per session, four days a week.

• Resistance training: Five sets of 12 repetitions, three days a week.

• Control: No prescribed stretching or strength programme.

The stretching group improved muscle thickness and maximal strength, with no statistically significant difference between its gains and those of the resistance-training group. Flexibility improvements favoured stretching.

Does Stretching Build as Much Muscle as Lifting Weights?

That headline needs context.

This study examined one muscle group, over eight weeks, using a substantial amount of supervised stretching. It does not establish that stretching and lifting weights are equally effective across different muscles, training programmes or populations.

It also does not mean a few stretches after your workout will produce the same results. The researchers highlighted the equipment and lengthy stretching sessions as practical limitations.

How Might Stretching Stimulate Muscle Growth?

One proposed explanation is mechanical tension: the sustained pulling force placed on muscle during a stretch.

Researchers suggest that sufficient tension, maintained for long enough, may stimulate adaptations associated with muscle growth. However, this remains a proposed mechanism rather than something the chest study directly proved.

A wider 2024 systematic review and meta-analysis also found evidence that regular static stretching can improve strength and muscle size, with results influenced by the training dose. This supports further investigation, while leaving questions about the most effective and practical approach.

What Does This Mean for Your Training?

The useful takeaway is to give flexibility training a clear purpose within your routine.

Keep resistance training central to your muscle-building plan. This research is a reason to explore stretching’s potential, rather than abandon a programme that is already helping you progress.

Distinguish flexibility training from muscle-growth protocols. Short, comfortable stretches and prolonged research interventions are different doses of training. You should not expect identical outcomes.

Build consistency before intensity. For everyday flexibility work, warm up first, move slowly and hold each stretch for around 30 seconds. Aim for tension rather than pain, breathe normally and avoid bouncing. Regular practice matters more than forcing yourself into a deeper position.

What About Assisted Stretching and PIR?

At FLX, we combine static assisted stretching with post-isometric relaxation (PIR) in structured stretch experiences.

These methods give practitioners ways to guide positioning, communicate with clients and adapt sessions to individual flexibility goals.

However, the chest study investigated sustained static stretching. It did not test the FLX system or PIR, so we cannot use its findings to promise equivalent muscle growth from those sessions.

Give Stretching a Place in Your Programme

Stretching’s potential to support muscle growth is an exciting area of research. The evidence gives us a reason to look beyond flexibility alone, while staying realistic about what different stretching routines can achieve.

For clients and practitioners, the practical goal remains clear: develop useful range of motion and the strength to control it.

Want to learn how to deliver structured assisted stretching sessions? Explore the FLX Practitioner PRO course and learn five complete stretch experiences, alongside the theory, practical techniques and business support to start taking clients.