"How many times per week should I stretch?" is one of the top three most common questions that I receive. The other two are "What stretches should I do?" and "How long will it take for me to become flexible?" The answer to these, and probably most other training-related questions, can be distilled down to, "It depends."
Although that might sound like an easy way for a coach to avoid questions they don't know how to answer, it's fundamentally accurate. Human biology is so infinitely variable from one person to another that the only way to know for sure what is optimal is through trial and error. (By the way, responding to a question with, "It depends" without further elaboration is a cheap answer. The coach/trainer should at least expand it to, "It depends on how your body responds to what you do," followed by a discussion about what the person asking the question is doing or plans to do.)
Many trainees won't like to hear that; a lot of coaches don't like to admit it, either. But the only way to know for sure what the optimal X is for a particular person is by having them actually do X and compare the results (i.e., how their body reacts to the training inputs) to variations in how they do X.
Therefore, my answer to anyone who asks me, "How many times per week should I stretch?" is almost always, "Try stretching X times one week, Y times the following week, and see how your flexibility improves and how it makes you feel."
The literature does provide some general guidelines regarding optimal stretching frequency to get you started. Bandy, Irion, & Briggler (1997) conducted a six-week study during which participants performed stretching of various durations and frequencies five days per week. They reported no difference between stretching once per day versus three times per day or between using a 30-second duration of stretch versus 60 seconds. From these results, we might conclude that holding a single 30-second stretch once per day is enough to improve flexibility. But while a single stretch might increase flexibility by a small amount each day, practical experience tells us that it usually doesn't provide enough stimulus to develop the permanent improvements in range of motion that many people seek.
Issues with the methodology of that particular study help to illuminate why the authors reported those results. They instructed the participants to move into the position only until they felt a gentle stretch in the target muscles. Gentle stretching implies that little force (tensile stress) was acting upon the muscles. Combined with the short stretching durations, it's possible that the interventions in that study didn't evoke sufficient change in the target tissues to produce any meaningful difference between groups.
Other studies that examined the effect of stretching frequencies reveal a consistent trend: more days seems to be more effective than fewer days. For example, Santonja Medina et al. (2007) reported that while stretching two days per week and four days per week both produced significant improvements in range of motion compared to controls, four days per week elicited more range of motion compared to two days per week.
Cipriani et al. (2012) reported that people who stretched every day achieved more range of motion overall than those who stretched three times per week. However, they also discovered that the rate of gain was similar between groups - as long as those who stretched only three times per week did so twice per day. In simple terms, it's possible the group that stretched three times per week would have achieved similar results as the group that stretched every day - it would just take them longer to do so (as long as they were stretching more times during the day).
These results suggest that there might be a minimum weekly effective dose that can be achieved either by stretching less times per day but more days per week, or by stretching more times per day but fewer days per week. Other data supports this idea.
In another study, one group of participants did six minutes of static passive stretching once per week. Another group stretched for two minutes, three days per week. The research team found that the group stretching only once per week didn't significantly change their range of motion or muscle stiffness. However, the group stretching three days per week increased range of motion and decreased tissue stiffness significantly. These results demonstrate that even when the weekly volume is equated, more applications (i.e., greater stretching frequency) is necessary for improving flexibility (Nakamura et al., 2020).
It's important to note that these results conflict with the findings of previous studies that stated total stretching duration is important for increasing range of motion (Medeiros & Martini, 2018; Thomas et al., 2018). The discrepancy between studies might be explained by a greater sustained effect of stretching on range of motion provided by the increased frequency.
For example, another study looked at the differences in holding stretches for 2, 4, and 8 minutes. The researchers found that range of motion increased initially for all groups, but it returned to baseline after 10 minutes (Ryan et al., 2008). In the Nakamura et al. (2020) study, range of motion could certainly have increased after both stretching interventions, but the acute effect might have disappeared after 10 minutes. It's possible that the group that stretched three times per week demonstrated improvements in range of motion and tissue compliance because a higher stretching frequency is essential for permanent increases in flexibility regardless of the total stretching duration.
Marques et al. (2009) reported that stretching three times per week was more effective than once per week but not more effective than stretching five times per week. Collectively, these results may suggest that around three times per week is an optimal frequency for static passive stretching. Therefore, starting your flexibility training programme by stretching three days per week is a reasonable option. Subsequent weeks should be guided by how well or how poorly three timers per week improves your range of motion. Keep in mind that these recommendations apply only to static passive stretching; guidance for other methods of flexibility training will be discussed in future posts.
Bandy, W. D., Irion, J. M., & Briggler, M. (1997) The Effect of Time and Frequency of Static Stretching on Flexibility of the Hamstring Muscles. Physical Therapy vol. 77, no. 10, pp. 1090-1096.
Santonja Medina, F. M., Sainz De Baranda Andujar, P., Rodriguez Garcia, P. L., Lopez Minarro, P. A., & Canteras Jordana, M. (2007) Effects of Frequency of Static Stretching on Straight-Leg Raise in Elementary School Children. Journal of Sports Medicine and Physical Fitness vol. 47, pp. 304-308.
Cipriani, D. J., Terry, M. E., Haines, M. A., Tabibnia, A. P., & Lyssanova, O. (2012) Effect of Stretch Frequency and Sex on the Rate of Gain and Rate of Loss in Muscle Flexibility During a Hamstring-Stretching Program. Journal of Strength and Conditioning Research vol. 26, no. 8, pp. 2119-2129.
Nakamura, M., Sato, S., Hirazumi, K., Kiyono, R., Fukaya, T., & Nishishita, S. (2020) Effects of Static Stretching Programs Performed at Different Volume-Equated Weekly Frequencies on Passive Properties of Muscle-Tendon Unit. Journal of Biomechanics vol. 103, no. 109670.
Medeiros, D. M., & Martini, T. F. (2018) Chronic Effect of Different Types of Stretching on Ankle Dorsiflexion Range of Motion: Systematic Review and Meta-Analysis. The Foot vol. 34, pp. 28-35.
Thomas, E., Bianco, A., Paoli, A., & Palma, A. (2018) The Relation Between Stretching Typology and Stretching Duration: The Effects on Range of Motion. International Journal of Sports Medicine vol. 39, no. 4, pp. 243-254.
Ryan, E. D., Beck, T. W., Herda, T. J., Hull, H. R., Hartman, M. J., Costa, P. B., & Cramer, J. T. (2008) The Time Course of Musculotendinous Stiffness Responses Following Different Durations of Passive Stretching. Journal of Orthopaedic and Sports Physical Therapy vol. 38, no. 10, pp. 632-639.
Marques, A. P., Vasconcelos, A. A., Cabral, C. M., & Sacco, I. C. (2009) Effect of Frequency of Static Stretching on Flexibility, Hamstring Tightness, and Electromyographic Activity. Brazilian Journal of Medical and Biological Research vol. 42, no. 10, pp. 949-953.