I have received a few calls from fitness professionals interested in the best way to stretch the hamstrings. Recently, I came across a study that investigated two stretching methods for the hamstrings.
Eight men and four women (age 27± four years) with no lower extremity abnormalities, performed one type of hamstring stretch on the left leg and a different hamstring stretch on the right leg. All subjects’ knee extension range of motion (ROM) were assessed to be less than 70 degrees of active knee extension (they couldn’t straighten their legs), while the hip was flexed and held at 90 degrees flexion (in a supine position). This method of determining hamstring extensibility has been suggested by Perrin et al. to be valid and reliable.
All subjects performed the first stretching technique with the heel of one leg up on a table, knee extended straight and ankle relaxed in plantar flexion. They then rotated the pelvis anteriorly while lengthening the spine (stuck the butt out and stood up tall). The researchers called this technique the Forward Swing Stretch or FSS (see Figure 1). Subjects then flexed forward at the hip to increase the stretch until they perceived tightness in the hamstring (not pain).
The second stretch, labeled the Stance Phase Stretch or SPS (see Figure 2), required subjects to take one small step forward (12 inches or so) and then slightly bend both knees. Next, they placed both hands on the front knee (leg to be stretched) and rotated the pelvis anteriorly while elongating the spine. Subjects then flexed forward at the hip to increase the stretch until they perceived tightness in the hamstring (not pain). To further accentuate the stretch, they then began extending the forward knee (straightening the leg being stretched).
Stretching protocol involved:
||Five days per week for two weeks at the same time each day
||To a comfortable "tightness"
||Five repetitions of 30 seconds each with 20 seconds rest between each repetition
||Same throughout the study
||Trained examiner observing and ensuring compliance
||All subjects were trained on technique before testing began
The results of this study revealed that although BOTH stretching techniques improved hamstring length, the SPS was significantly more effective at increasing knee joint ROM. The SPS group improved, on average, 12.83 degrees (range 7.5-24.5 degrees) while the FSS group improved eight degrees (0 to 16 degrees). These improvements in ROM are in accordance with other similar stretching studies.
The results of this study imply that although both stretching methods are capable of improving hamstring length, if lack of time is a factor, trainers may choose to focus on the SPS method in order to maximize a client's stretching efforts. Also, it is important to note that the FSS stretch with the hip flexed to 90 degrees has been considered by some experts to cause a slight impingement of the sciatic nerve (in those with a pre-disposition for impingement). Trainers should look for any numbness, tingling or related neurological symptoms when performing this particular stretch. If symptoms do occur, then this stretch should be substituted for the SPS.
The results of this study are encouraging. However, they should not be interpreted as conclusively stating that the SPS method is the better of the two. Here’s why:
- The sample size was quite small (always a statistical issue), which makes it harder to generalize to the larger population.
- The intensity of the stretch was still somewhat subjective. Subjects stretched to a vague "comfortable" ROM. Perhaps using a graded 0 to 10 intensity scale and asking the subjects to stretch at a four would have controlled for this possible confounding factor.
- The FSS position may not make it possible to maintain the same level of anterior pelvic tilt as the SPS, since FSS subjects had to flex the hip over a greater ROM to get the same stretch "feeling." If the pelvis rolls more posteriorly during the FSS, then this may impose a smaller demand on the hamstring and, as a result, a lower response to elongate.
Stretching studies always have a great many variables that need to be controlled. Unfortunately, researchers are well aware that this is not always easy or possible. This is why we have so many conflicting studies telling us how to stretch. So, where does this leave you? Try the stretches yourself and decide which one feels right for you. This, of course, does not mean that it is right for your client. You’ll need to assess your client’s attitude regarding stretching, comfort level, time constraints, etc. and pick the ones that work. Remember, the best stretch is the one your client will do!
- Bandy WD and Irion JM. The effect of time on static stretch on the flexibility of the hamstring muscles. Physical Therapy. 74: 845-850, 1994.
- Perrin DH. The evaluation process in rehabilitation. Rehabilitation Techniques in Sports Medicine, 2nd edition. W.E Prentice, St. Louis: Mosby Year Book Inc.
- Prentice WE. A comparison of static stretching and PNF stretching for improving hip joint flexibility. Athletic Training. 18: 56-59, 1983.
- Ross M. Effect of lower-extremity position and stretching on hamstring muscle flexibility. Journal of Strength and Conditioning. 13(2): 124-129, 1999
- Sullivan MK, DeJulia JJ and Worrell TW. Effect of pelvic position and stretching method on hamstring muscle flexibility. Medicine and Science in Sports and Exercise. 24: 1383-1389, 1992.
- Worrell TW, Smith TL, and Winegardner J. Effect of hamstring stretching on hamstring muscle performance. Journal of Orthopaedic Sports Physcial Therapy. 20: 154-159, 1994.