Having tight hamstrings is an issue for a lot of people. This research below shows that using a foam roller to self release does not improve the length of the tissue. Perhaps more research should be performed on eccentric loading to increase muscular length.
Self-myofascial release does not improve functional outcomes in ‘tight’ hamstrings by Morton, Oikawa, Phillips, Devries, & Mitchell, in International Journal of Sports Physiology and Performance (2015)
Self-myofascial release (SMR) is simply that category of myofascial release techniques that are performed by the individual themselves rather than by a clinician. Consequently, SMR techniques most often involve a tool with which the individual puts pressure upon the affected area. The most commonly-used SMR tool is the foam roller. For a detailed introduction to fascia, self-myofascial release and the foam roller, see the earlier study review.
OBJECTIVE: To compare the long-term effects of a combined program of self-myofascial release (foam rolling) and static stretching (SMR+SS) with a program of static stretching only (SS) on knee extension ROM (as measured with a passive knee extension test using a dynamometer), peak passive torque (measured during the passive knee extension test with the dynamometer), hamstring muscle stiffness (measured by the slope of the torque-angle curve in the knee extension test in the dynamometer) and hamstring strength (as measured by maximum voluntary isometric contraction (MVIC) torque in the dynamometer) in young males with low hamstrings flexibility.
POPULATION: 19 male subjects, aged 22 ± 3 years. The subjects were assessed for leg dominance and each leg was allocated into either the SMR+SS or SS conditions.
INTERVENTION:All subjects performed 4 static stretches lasting 45 seconds, 2 times per day for 4 weeks on both legs. In the SMR+SS condition, the subjects also performed 4 bouts of foam rolling, lasting 60 seconds each, prior to each stretching session.
Effects on flexibility
The researchers found that flexibility (as measured by peak knee extension angle) increased significantly by 8 ± 2 degrees in the SS leg and 9 ± 2 degrees in the SMR+SS leg. There were no significant differences between conditions.
Effects on peak passive torque and stiffness
The researchers found that peak passive torque (as measured by the dynamometer at the point of peak knee extension angle) increased significantly by 5 ± 8Nm in the SS leg and 6 ± 14Nm in the SMR+SS leg. Stiffness was only altered at end ROM. There were no significant differences between the two conditions for either peak passive torque or stiffness.
The researchers found that MVIC torque (as measured by the dynamometer) increased significantly by 5 ± 9Nm in the SS leg and by 2 ± 9Nm in the SMR+SS leg. There were no significant differences between the two conditions for either peak passive torque or stiffness.
What did the researchers conclude?
The researchers concluded that adding foam rolling to a static stretching program does not add any effects in respect of flexibility, stiffness or strength. Whether the foam rolling program would have produced similar effects to the static stretching program if conducted alone is unclear.
The study was limited by the lack of a control group and by the lack of a single group that only performed SMR.