Can Strength Training Replace Stretching for Flexibility?

What the evidence can tell you about flexibility without separate stretching

In these studies, flexibility changed depending on how training was set up (for example, resistance training performed through full range of motion improved a flexibility measure in one trial, while resistance training alone did not change flexibility in another).

In the reviewed studies, resistance training improved flexibility measures in some setups, but results depended on how the training was set up.

A 6-week randomized trial in physically active young adults (18–25) compared low-volume static stretching to low-volume resistance training done through full range of motion (RT). In that 6-week trial, both static stretching and full range-of-motion resistance training improved posterior chain flexibility compared with the no-intervention control group. In the RT group, posterior chain range of motion also increased compared with control Low-volume static stretching vs full range-of-motion resistance.

In that study, the posterior chain range-of-motion increase for the full range-of-motion resistance training group was statistically significant compared with control. In that trial, full range-of-motion resistance training (done with time matched to stretching) improved the study’s posterior chain flexibility/range-of-motion measure.

When resistance training alone does not increase flexibility

Not every study finds the same effect.

In another 12-week trial in healthy young adults (twice per week), resistance training improved strength, but it did not change flexibility when resistance training was done by itself. Flexibility increased when participants trained flexibility specifically, and adding resistance training did not block those flexibility gains Interaction between resistance and flexibility training.

That difference is why the “strength training without separate stretching” idea varies by setup. In these trials, resistance training by itself did not increase flexibility, while flexibility gains occurred with flexibility-specific training (and were not prevented by combining training types).

A short-term hamstring study (single 15-minute session) compared hamstring-focused resistance training with static/ballistic stretching and stationary cycling. After hamstring resistance training, range of motion did not increase, while ROM increased after 15 minutes of static or ballistic stretching and after 15 minutes of stationary cycling Hamstring strength vs stretching and cycling.

The report available here doesn’t provide enough detail to confirm whether the resistance training was performed through a stretching-matched end range. Still, the broader pattern across the trials is that flexibility outcomes depend on the training design and what is measured.

A practical way to interpret this in these studies

• Yes, sometimes. In one 6-week trial, low-volume full range-of-motion resistance training improved posterior chain flexibility/range of motion compared with a no-intervention control.
• But not always. In another 12-week trial, resistance training by itself did not increase flexibility.

Bottom line: in these studies, flexibility gains were not guaranteed from resistance training alone; they depended on the training set-up (for example, low-volume full range-of-motion work). The studies here don’t establish a specific dose of full-range-of-motion resistance work that reliably replaces dedicated stretching across people or exercises.