Danny McMillian PT, DSc, OCS, CSCS
Title: The Effect of Symmetrical, Hand-held Load Carriage on Thoracic Rotation during Gait: An Observational Study
Authors: Danny J. McMillian, PT, DSc, OCS, CSCS ; Robert C. Bennett, SPT ; Claire E. Tenenbaum, SPT ; Daniel C. Winnwalker, SPT
Affiliation: Physical Therapy Program, University of Puget Sound
Purpose: During unloaded ambulation arm, trunk and leg motion produces reciprocal, anti-phase rotation between the pelvis and thoracic spine. Anti-phase rotation allows for efficient, stable gait patterns and promotes balanced segmental forces. Research demonstrates that several common factors cause in-phase thoracic spine and pelvic rotation resulting in decreased gait efficiency. Factors include load carriage, slow gait velocity, and locomotor pathologies that promote protective spinal stabilization such as low back pain and pregnancy-related pelvic girdle pain. Since painful spinal and pelvic conditions are frequently treated with physical therapy interventions that promote stabilization, clinicians should be cognizant of the degree to which such exercises may alter normal gait mechanics.A previous, as yet unpublished study from our lab has shown that gait mechanics transition from anti-phase to in-phase rotation with as little as 5% of an individual’s body weight carried as a asymmetrical hand-held load. The purpose of the current study was to establish if altered gait kinematics, specifically thoracic spinal rotation relative to the pelvis, occurs with symmetrical hand-held loads.
Subjects: Adult volunteers, 18-30 years old, with no gait or health complications.
Materials & Methods: Each subject walked at a cadence of 100 beats per minute for a distance of 48 feet and repeated seven different conditions three times in randomized order. The conditions were: 1) no load, 2) holding an empty canvas bag in each hand, 3) holding 2% of body weight (BW), 4) holding 4% BW, 5) holding 6% BW, 6) holding 8% BW, and 7) holding 10% BW. Each percentage of BW was carried bilaterally and subjects were blinded to conditions 2-7. Ten Bonita cameras recorded each condition at 120 hertz, and gait kinematics were analyzed with VICON Nexus 1.8.4 motion analysis system. In order to compare the average thoracic rotation relative to the pelvis for each condition a repeated measures ANOVA with Bonferroni adjustment was performed with alpha value p<0.05.
Results: Compared to condition 1 (unloaded walking), condition 2-7 demonstrated significant decrease in rotational angles of the thoracic spine relative to the pelvis (p<0.001). Furthermore, condition 2 demonstrated a significant decrease in thoracic rotation as compared to conditions 5 (p<0.004) and 7 (p<0.034).
Conclusion: Thoracic spine rotation decreases when walking with unloaded bags in each hand. Diminished rotation was likely due to decreasing arm swing. Consistent with the effects of muscular stabilization, increased load generally decreased rotation further.
Clinical Relevance: This information is clinically applicable when working with individuals who have some degree of in-phase gait kinematics and need rehabilitation in order to return to activities that necessitate gait with hand-held loads. In these cases, clinicians should consider first reestablishing optimal transverse plane kinematics, then incorporating only the minimally necessary amount of hand-held load.
University of Puget Sound
Bennett, Robert; Tenenbaum, Claire E.; and Winnwalker, Danny C., "The Effect of Symmetrical, Hand-held Load Carriage on Thoracic Rotation during Gait: An Observational Study" (2015). Physical Therapy Research Symposium. 10.