Influencing lumbar posture through real-time biofeedback and its effects on the kinematics and kinetics of a repetitive lifting task.

BACKGROUND: Repetitive, flexed lumbar postures are a risk factor associated with low back injuries. Young, novice workers involved in manual handling also appear at increased risk of injury. The evidence for the effectiveness of postural biofeedback as an intervention approach is lacking, particularly for repetitive, fatiguing tasks. RESEARCH QUESTION: How does real-time lumbosacral (LS) postural biofeedback modify the kinematics and kinetics of repetitive lifting and the risk of low back injury? METHODS: Thirty-four participants were randomly allocated to two groups: biofeedback (BF) and non-biofeedback (NBF). Participants repetitively lifted a 13 kg box at 10 lifts per minute for up to 20 min. Real-time biofeedback of LS posture occurred when flexion exceeded 80% maximum. Three-dimensional motion analysis and ground reaction forces enabled estimates of joint kinematics and kinetics. Rating of perceived exertion (RPE) was measured throughout. RESULTS: The BF group adopted significantly less peak lumbosacral flexion (LSF) over the 20 min when compared to the NBF group, which resulted in a significant reduction in LS passive resistance forces. This was accompanied by increased peak hip and knee joint angular velocities in the BF group. Lower limb moments did not significantly differ between groups. Feedback provided to participants diminished beyond 10 min and subjective perceptions of physical exertion were lower in the BF group. SIGNIFICANCE: Biofeedback of lumbosacral posture enabled participants to make changes in LSF that appear beneficial in reducing the risk of low back injury during repetitive lifting. Accompanying behavioural adaptations did not negatively impact on physical exertion or lower limb joint moments. Biofeedback of LS posture offers a potential preventative and treatment adjunct to educate handlers about their lifting posture. This could be particularly important for young, inexperienced workers employed in repetitive manual handling who appear at increased risk of back injury.

Gait Deviation Index Correlates With Daily Step Activity in Children With Cerebral Palsy.

OBJECTIVES: To examine the association between the Gait Deviation Index (GDI), a multivariate measure of overall gait impairment, and measures of both community walking performance and walking capacity within the clinic setting in ambulatory children with cerebral palsy. DESIGN: Cross-sectional study. SETTING: Gait analysis, 6-minute walk test (6MWT), and self-selected walking speed (WS) were conducted in laboratory and clinic settings. Activity monitoring was done in participants' community environment. PARTICIPANTS: Children with cerebral palsy (N=55; age range, 6-18y) with Gross Motor Function Classification System levels I to III. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The GDI was derived from gait analysis data as a measure of overall gait impairment; an activity monitor was used to capture community walking performance, and the 6MWT and WS were the clinic-based measures of walking capacity. RESULTS: Fifty-five children had a median GDI of 78.86 (range, 53.07-105.34). A moderate association was found between the GDI and daily step count (Spearman ρ=.58; 95% confidence interval [CI], .37-.74; P<.0001). Weaker associations were found between the GDI and 6MWT (Spearman ρ=.4718; 95% CI, .2283-.6597; P<.0003) and between the GDI and WS (Spearman ρ=.3949; 95% CI, .1368-.6028; P<.0028). CONCLUSIONS: The GDI has a moderate association with daily step count, which suggests that interventions that positively change gait kinematics may also affect community walking performance. Although the GDI's deviation from the normal value provides valuable information, other measures are required to provide a complete picture of a child's walking capacity and performance.