Nishimoto K1,2, Yasuda M1, Hori M1, Noguchi T1, Takasaki H1
1Saitama Prefectural University, Physical Therapy, Koshigaya, Japan, 2Tokyo Women’s Medical University Yachiyo Medical Center, Department of Rehabilitation, Yachiyo, Japan
Background: There is considerable interest amongst physiotherapists in relative stiffness between muscles acting on the lumbar spine and those muscles in adjacent areas as potential biomechanical contributing factors to low back pain (LBP). The hamstring muscle is one example. Jack-knife stretching (JKS) and active knee extension stretching while controlling the spine (AKES) are methods of stretching the hamstring muscles. In JKS, lumbar extensor muscles are elongated during stretching and relative stiffness between the hamstring and lumbar extensor muscles that can be measured with active knee extension test in sitting (AKEiSit) may not change. Further, JKS may cause LBP greater than AKES due to greater lumbar flexion.
Purpose: To compare the effects of JKS and AKES on sagittal lumbopelvic curvature from T12 to S2 (θ value) during the AKEiSit and the prevalence of LBP following the intervention period for each stretching method.
Methods: This study was a two-arm randomized controlled trial with a 5-week follow-up. Primary inclusion criterion of participants was clinical dysfunction in relative stiffness between the hamstring and lumbar extensor muscles, where loss of lumbar lordosis from neutral occurred during the AKEiSit. Interventions included home exercises with JKS or AKES, where the stretching protocol for each group was sustained holding for 15 seconds of four repetitions with three sets per day. A primary outcome was θ value during the AKEiSit, which was traced on paper using a flexible ruler and calculated with two methods (2-point-method and max-method). Another was prevalence of LBP in the JKS group. We undertook a two-way repeated measure ANOVA for the θ value. As post-hoc, we undertook the two-tailed dependent sample t-test to investigate changes of the θ values from the baseline to the follow-up session in each group. We also calculated Hedges g for effect size. We compared the prevalence of LBP in the JKS group with that in the AKES group using the number need to treat (NNT). In the NNT analysis, no difference in the prevalence of LBP between the two groups was indicated when the 95% confidence intervals (CIs) of the NNT included zero.
Results: Fifty-four participants (mean age 20.2 years) were randomized. An interaction effect was not detected in either method for the θ value (All P>.05). Post-hoc analyses demonstrated statistically significant reduction of θ values from the baseline in the 2-point method (P=.02 [g=0.35] in the JKS and P .001 [g=0.49] in the AKES) and partially demonstrated that in the max-method (P=.06 [g=0.26] in the JKS and P .002 [g=0.42] in the AKES). The 95% CIs of the NNT were -3 and 5.
Conclusion(s): In young healthy individuals, AKES reduces relative stiffness of hamstring to lumbar extensor muscles at least as well as JKS, and JKS does not appear to be harmful in comparison to AKES.
Implications: The optimal stretching method to reduce the relative stiffness of the hamstring to lumbar extensor muscles during knee movements is unclear. However, considering pre-post effect sizes, the AKES exercise may be more promising than the JKS exercise.
Keywords: hamstring, stretching exercises, relative flexibility
Funding acknowledgements: No funding
Purpose: To compare the effects of JKS and AKES on sagittal lumbopelvic curvature from T12 to S2 (θ value) during the AKEiSit and the prevalence of LBP following the intervention period for each stretching method.
Methods: This study was a two-arm randomized controlled trial with a 5-week follow-up. Primary inclusion criterion of participants was clinical dysfunction in relative stiffness between the hamstring and lumbar extensor muscles, where loss of lumbar lordosis from neutral occurred during the AKEiSit. Interventions included home exercises with JKS or AKES, where the stretching protocol for each group was sustained holding for 15 seconds of four repetitions with three sets per day. A primary outcome was θ value during the AKEiSit, which was traced on paper using a flexible ruler and calculated with two methods (2-point-method and max-method). Another was prevalence of LBP in the JKS group. We undertook a two-way repeated measure ANOVA for the θ value. As post-hoc, we undertook the two-tailed dependent sample t-test to investigate changes of the θ values from the baseline to the follow-up session in each group. We also calculated Hedges g for effect size. We compared the prevalence of LBP in the JKS group with that in the AKES group using the number need to treat (NNT). In the NNT analysis, no difference in the prevalence of LBP between the two groups was indicated when the 95% confidence intervals (CIs) of the NNT included zero.
Results: Fifty-four participants (mean age 20.2 years) were randomized. An interaction effect was not detected in either method for the θ value (All P>.05). Post-hoc analyses demonstrated statistically significant reduction of θ values from the baseline in the 2-point method (P=.02 [g=0.35] in the JKS and P .001 [g=0.49] in the AKES) and partially demonstrated that in the max-method (P=.06 [g=0.26] in the JKS and P .002 [g=0.42] in the AKES). The 95% CIs of the NNT were -3 and 5.
Conclusion(s): In young healthy individuals, AKES reduces relative stiffness of hamstring to lumbar extensor muscles at least as well as JKS, and JKS does not appear to be harmful in comparison to AKES.
Implications: The optimal stretching method to reduce the relative stiffness of the hamstring to lumbar extensor muscles during knee movements is unclear. However, considering pre-post effect sizes, the AKES exercise may be more promising than the JKS exercise.
Keywords: hamstring, stretching exercises, relative flexibility
Funding acknowledgements: No funding
Topic: Musculoskeletal; Musculoskeletal: spine; Musculoskeletal: lower limb
Ethics approval required: Yes
Institution: Saitama Prefectural University
Ethics committee: Research Ethics Committee
Ethics number: 27780
All authors, affiliations and abstracts have been published as submitted.
