How to use Strength Training to Gain Flexibility

Sep 24, 2020

Written by Isaac Auyeung, PT, DPT, CSCS

Have you ever wanted to improve your flexibility because you feel stiff?

Have you ever stretched and stretched without feeling like your flexibility improved?

Do you not have the time to stretch after working out? Well, I have some good news for you!

Research is showing that strength training is just as good as stretching for flexibility. Strength has also been shown throughout literature to have many benefits, including improving balance, decreasing risk of falls, and improving sports performance.1,2

You can’t go wrong with getting stronger. However, you can also target flexibility at the same time through strength training. In this blog post, we will compile what the research says and then provide practical tips for you to start getting those improvements in flexibility while getting stronger at the same time! 

If you’re not a fan of reading through research, you can skip to the bottom for a summary.


Without further ado, let’s dive into the research:

  • In one study that compared full range resistance training versus static stretching, there was no difference found in the flexibility of multiple joints after just 5 weeks of strength training.3 
  • In another study, individuals with tight hamstrings (you might be able to relate) were split into three groups: a control, stretching, and strength training group. Both the stretching and strengthening group demonstrated improved hamstring flexibility, but only the strengthening group improved in strength.4 
  • “How often do I have to work out?”, you might ask. Researchers found that there was no significant difference between performing one set, three sets, or five sets of an exercise.5 
  • Lastly, another clinical study looked at the effect of resistance training performed at different weekly frequencies on the flexibility in older women. Both the group that exercised twice a week and the group that exercised three times a week demonstrated improved flexibility. In general, there may be greater benefit to increasing the training volume for a given muscle.6 

Based on all these studies, here are some principles of strength training to improve flexibility:

  1. Length of time – you should be able to see results in as little as 5 weeks!3 
  2. Range of motion – exercises need to be performed through the full range of motion in order to be effective.3 
  3. Repetitions – typically 8-12 RM (your muscle should be pretty tired after finishing your 10th rep) or 60-80% of your 1 rep max.4 
  4. Sets – just one set is enough to create change.5
  5. Frequency – the more frequent, the better. At least twice a week will be effective, but three times a week would result in greater improvements.
  6. Age – the research was performed on college-aged students all the way to older women in their 60’s. However, strength training is safe for kids as young as 8 years old according to the Mayo Clinic. Similarly, strength training is also appropriate, and often much needed in seniors, as long as the strengthening is progressed gradually. If you have any concerns, please reach out to a healthcare professional at Evergreen PT for guidance!

You might still have questions about breathing techniques, how to progress the weights, and which exercises you should do.

If you want 1 on 1 guidance through a personalized strength training program, please visit us at Evergreen Physical Therapy for us to take your strength and flexibility to the next level!

Stay healthy. Stay well. Stay active. 

 Isaac is recognized as an EXOS Performance Specialist and Certified Strength and Conditioning Specialist. Immediately after earning his Doctorate of Physical Therapy from Mount Saint Mary's University, he completed a year-long orthopedic residency program through Kaiser Permanente. He is currently furthering his expertise as a movement specialist through Azusa Pacific University's Movement and Performance Fellowship. Isaac is passionate about using his knowledge to help his community. He has volunteered on the medical team with AVP pro beach volleyball, the Lei-Out ultimate frisbee tournament, South Bay Dozen ocean racing event, and an international hip hop dance competition. 


Schedule an appointment to begin your strength training for flexibility today!



  1. Lee, I. and Park, S., 2013. Balance Improvement by Strength Training for the Elderly. Journal of Physical Therapy Science, 25(12), pp.1591-1593.
  2. McGuigan, M., Wright, G. and Fleck, S., 2012. Strength Training for Athletes: Does It Really Help Sports Performance?. International Journal of Sports Physiology and Performance, 7(1), pp.2-5.
  3. Morton, S., Whitehead, J., Brinkert, R. and Caine, D., 2011. Resistance Training vs. Static Stretching: Effects on Flexibility and Strength. Journal of Strength and Conditioning Research, 25(12), pp.3391-3398.
  4. Aquino, C., Fonseca, S., Gonçalves, G., Silva, P., Ocarino, J. and Mancini, M., 2010. Stretching versus strength training in lengthened position in subjects with tight hamstring muscles: A randomized controlled trial. Manual Therapy, 15(1), pp.26-31.
  5. Leite, T., Júnior, R., and Reis, V., 2011. Influence of the Number of Sets at a Strength Training in the Flexibility Gains. Journal of Human Kinetics, 29A(Special-Issue).
  6. Ribeiro, A., Carneiro, N., Nascimento, M., Gobbo, L., Schoenfeld, B., Achour Júnior, A., Gobbi, S., Oliveira, A. and Cyrino, E., 2015. Effects of different resistance training frequencies on flexibility in older women. Clinical Interventions in Aging, p.531.

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