Jack-knife stretching promotes flexibility of tight hamstrings after 4 weeks: a pilot study
- 845 Downloads
Tight hamstrings are reported to be one of the causes of low back pain. However, there have been few reports on effective stretching procedures for the tight hamstrings. The so-called jack-knife stretch, an active-static type of stretching, can efficiently increase the flexibility of tight hamstrings. To evaluate hamstring tightness before and after the 4-week stretching protocol in healthy volunteer adults and patients aged under 18 years with low back pain. For understanding the hamstrings tightness, we measured two parameters including (1) finger to floor distance (FFD) and (2) pelvis forward inclination angle (PFIA). Eight healthy adult volunteers who had no lumbar or hip problems participated in this study (mean age: 26.8 years). All lacked flexibility and their FFD were positive before the experiment. Subjects performed 2 sets of the jack-knife stretch every day for 4 weeks. One set consisted of 5 repetitions, each held for 5 s. Before and during the 4-week experiment, the FFD and PFIA of toe-touching tests were measured weekly. For 17 of the sports players aged under 18, only FFD was measured. In adult volunteers, FFD was 14.1 ± 6.1 cm before the experiment and decreased to −8.1 ± 3.7 cm by the end of week 4, indicating a gain in flexibility of 22.2 cm. PFIA was 50.6 ± 8.2 before the experiment and 83.8 ± 5.8 degrees after. Before and after the experiment, the differences were significant (p < 0.05). For those aged under 18, FFD was 8.1 ± 8.0 and −9.6 ± 6.8, before and after the stretching, respectively. This difference was significant (p < 0.05). The jack-knife stretch is a useful active-static stretching technique to efficiently increase flexibility of tight hamstrings.
KeywordsStretch Low back pain Hamstrings Lumbar spine Conservative treatment
The authors thank Mr. Ryota Kawada for his technical advice regarding the jack-knife stretch.
Conflict of interest
No funds were received in support of this study.
- 6.Esola MA, McClure PW, Fitzgerald GK, Siegler S (1996) Analysis of lumbar spine and hip motion during forward bending in subjects with and without a history of low back pain. Spine (Phila Pa 1976) 21:71–78Google Scholar
- 8.Mierau D, Cassidy JD, Yong-Hing K (1989) Low-back pain and straight leg raising in children and adolescents. Spine (Phila Pa 1976) 14:526–528Google Scholar
- 10.White SG, Sahrmann SA (1994) A movement system balance approach to management of musculoskeletal pain. In: Grant R (ed) Physical therapy of the cervical and thoracic spine. Churchill Livingstone Inc, New York, pp 339–357Google Scholar