The Effects of Spinal Mobilization on Hamstring Strength and Endurance

Open Access
Kalajainen, Amy Michelle
Area of Honors:
Athletic Training
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Sayers John Miller Iii, Thesis Supervisor
  • Giampietro Luciano Vairo, Thesis Supervisor
  • Steriani Elavsky, Honors Advisor
  • spinal mobilization
  • hamstring
  • knee flexor
  • strength
  • endurance
Objective: To primarily investigate the immediate and one-week delayed effects of spinal Grade V mobilization on knee flexor strength and endurance in individuals with limited hamstring extensibility. We hypothesized that spinal mobilization would increase strength and endurance immediately following and one-week post-mobilization. Design and Settings: A pre-test, post-test study was conducted in a controlled laboratory. The independent variable was spinal mobilization. Dependent variables included concentric isokinetic knee flexor strength and endurance. Participants underwent three separate testing sessions. The first session included baseline testing. The second session was separated by 48-72 hours and included spinal mobilization and knee flexor testing. The third session was separated by seven days and included only knee flexors testing. The order of testing the dominant and non-dominant leg was randomized to prevent order effects. Subjects: Twenty-one (14 male, 7 female) healthy, physically active participants (20.0 ± 1.2 years, 1.7 ± 0.1 m, 69.9 ± 12.4 kg) with a straight leg raise of less than 70 (61.1 ± 5.3) were enrolled. Measurements: Peak moment normalized to body mass, time to peak moment, peak moment angle, average power and total work to body mass were collected using valid and reliable isokinetic testing protocols. Group means and standard deviations were calculated by testing session. One-way analyses of variance with Tukey’s post hoc test calculated differences among testing sessions. P ≤ 0.05 denoted statistical significance. Results: No statistically significant differences existed for all the strength and endurance measures among testing sessions for the dominant and non-dominant legs; [dominant flexion: peak moment (baseline = 1.036 ± 0.402, immediately post = 1.046 ± 0.435, week-post = 1.046 ± 0.435; P = 0.993); total work (baseline = 14.676 ± 8.883, immediately post =14.455 ± 8.454, week-post = 15.791 ± 11.211; P=0.890)]; [non-dominant flexion: peak moment (baseline = 0.920 ± 0.390, immediately post = 0.973 ± 0.462, week-post = 0.982 ± 0.475; P=0.885); total work (baseline = 13.525 ± 8.739, immediately post = 15.004 ± 9.186, week-post = 13.931 ± 8.377, P=0.853)]. Conclusions: Our findings suggest that one bout of spinal mobilization elicits no significant immediate or delayed effect on knee flexor strength or endurance measures in a healthy, physically active population with limited hamstring extensibility. Additional investigation is warranted to determine the effects of spinal mobilization on knee flexor performance.