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Take Home Points:
  • SMR appears effective for improving ROM
  • SMR for 3 – 4 minutes likely doesn’t decrease EMG
  • Much more research is needed on SMR

Foam roll and tennis ball mobility or self myofascial releases (SMR) have become more common swim decks in the recent years, despite much clinical research. However, there is preliminary research suggesting this new form of mobility is more beneficial than stretching in numerous ways. We’ve discussed stretching previously on this website:

After reading these pieces, you may think stretching is the worst activity in the world, but remember individual differences do exist. However, it seems it is unnecessary for the majority of swimmers. In fact, SMR is likely a part of the replacement plan.

Fascia Restrictions
Fascia restrictions often occur in response to an injury, causing fascial tissue to lose elasticity and become dehydrated. This can cause fibrous adhesions and tightness, potentially leading to pain and decrease in soft-tissue extensibility.

In the past two years, there have been three main studies on SMR. 

MacDonald 2012:
Eleven healthy male subjects participated in maximal quadriceps contraction, evoked force and activation, and knee joint range of motion were measured two minutes and 10 minutes ,following two conditions: 1) two, one minute trials of SMR of the quadriceps via a foam roll and 2) no SMR. The SMR had an improved of 10 and 8% at 2 and 10 minutes. Force production and strength did not decrease following SMR.  An acute bout of SMR of the quadriceps was an effective treatment to acutely enhance knee joint range of motion without a concomitant deficit in muscle.
Practical Implication

MacDonald 2013:
Eleven healthy male subjects (mean age 22.3) rolled a uniform polystyrene foam roll under one thigh for three – four minute intervals. Then the electromyography (EMG) and the range of motion (ROM) of the quadriceps were measured. No differences in EMG data resulted after the foam rolling. However, a significant improvement in knee flexion ROM occurred after the foam rolling. ROM persisted 12.7 and 10.3% at 2 and 10 minutes after rolling. The improvements in ROM may have occurred by softening of the fascia (via heat and mechanical stress). Not finding a decrease in EMG compared to massage studies may be due to the length of the application, as massage studies have typically been longer (40 minutes).

Okamoto 2013: 

Ten healthy individuals (7 M: 3 F; mean age 19.9) with no cardiovascular symptoms without a history of SMR participated in the study. Pulse wave velocity, ankle-brachial index, and plasma nitric oxide (NO) concentration were measured before and after the foam roll was performed SMR of the adductor, hamstrings, quadriceps, iliotibial band and trapezius. For the foam roll trial, each participant performed 20 repetitions on each muscle group on a 1-minute interval. For the control trial, participants rested in a quiet room.The brachial-ankle index pulse wave velocity decreased significantly after the SMR trial. Plasma NO increased significantly after the SMR trial. These results suggest SMR provides a favorable effect on arterial function. This may occur by decreasing arterial stiffness.

What we Don’t Know
Here are just some things we still don’t know about SMR:
  • How does it influence endurance performance?
  • What is the exact mechanism(s) for improving ROM?
  • Does this work at every muscle? 
  • What is the ideal length for SMR?
  • Do you get the same results with tennis balls, baseballs, rollers, etc.?

Practical Implication
Foam rolling for 3 – 4 minutes of the quadriceps improves knee flexion by 10 degrees for at least 10 minutes. This improvement does not decrease EMG and may result from improving arterial mobility. Further research is required, but SMR should replace stretching. 


  1. Macdonald G, Penney M, Mullaley M, Cuconato A, Drake C, Behm DG, Button DC. An Acute Bout of Self Myofascial Release Increases Range of Motion Without a Subsequent Decrease in Muscle Activation or Force. J Strength Cond Res. 2012 May 10.
  2. Macdonald GZ, Penney MD, Mullaley ME, Cuconato AL, Drake CD, Behm DG, Button DC. An Acute Bout of Self-Myofascial Release Increases Range of Motion Without a Subsequent Decrease in Muscle Activation or Force. J Strength Cond Res. 2013 Mar;27(3):812-821. 
  3. Okamoto T, Masuhara M, Ikuta K. Acute Effects of SelfMyofascial Release Using a Foam Roller on Arterial Function. J Strength Cond Res. 2013 Apr 9. [Epub ahead of print]
By Dr. G. John Mullen received his Doctorate in Physical Therapy from the University of Southern California and a Bachelor of Science of Health from Purdue University where he swam collegiately. He is the founder of Mullen Physical Therapy, the Center of Optimal Restoration, head strength coach at Santa Clara Swim Club, creator of the Swimmer’s Shoulder System, and chief editor of the Swimming Science Research Review.


Dr. John Mullen, DPT, CSCS world-renowned physical therapist and strength coach.
  1. August 17, 2013

    “However, there is
    preliminary research suggesting this new form of mobility is more
    beneficial than stretching in numerous ways.”

    Kind of funny, because SMR is also a form of local stretching through pressure differentials. (Poisson effect)

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