Attenuation of Lower Body Acceleration in Overweight and Healthy-Weight Children During Running.

This study aimed to identify differences in ground impact shock attenuation between overweight and healthy-weight children during running. Twenty overweight children aged 8.4 (1.1) years and 12 healthy-weight children aged 10.7 (1.3) years ran on a treadmill (120% of baseline speed) while wearing 2 inertial sensors located on their distal tibia and lower back (L3). Peak acceleration attenuation coefficient at foot contact and transfer function of the acceleration were calculated. Peak positive acceleration values were not significantly different between the overweight children and healthy-weight children (3.98 [1.17] g and 3.71 [0.84] g, respectively, P = .49). Children with healthy weight demonstrated significant greater attenuation as evident by greater peak acceleration attenuation coefficient (35.4 [19.3] and 11.9 [27.3], respectively, P < .05) and lower transfer function of the acceleration values (-3.8 [1.9] and -1.2 [1.5], respectively, P < .05). Despite the nonsignificant differences between groups in tibia acceleration at foot-ground impact that was found in the current study, the shock absorption of overweight children was reduced compared with their healthy-weight counterparts.

Repeatability of tibial acceleration measurements made on children during walking and running.

OBJECTIVES: To determine the between-visit reliability of an accelerometer as a measure of lower-extremity impact acceleration at a variety of gait speeds in children. DESIGN: Absolute reliability assessment. METHODS: Ten children with no known gait pathology attended two testing sessions, three weeks apart. A tri-axial accelerometer was fixed to the child's distal tibia to measure peak positive acceleration responses while walking and running on the treadmill at three different speeds (comfortable walking, threshold walking, and jogging). Reliability of the average and standard deviation Peak Positive Acceleration (avgPPA and sdPPA, respectively) was calculated by intra-class correlation coefficients (ICC) and Minimum Detectable Change (MDC). RESULTS: Excellent reliability was indicated with ICC values for avgPPA of 0.90, 0.95, and 0.81 for comfortable walking, threshold walking, and jogging, respectively. Moderate reliability was found for the sdPPA measures. MDC values were calculated to be 18%, 26%, and 23% for comfortable walking, threshold walking, and jogging, respectively, indicating the amount by which an avgPPA value would need to change to ensure that the change is greater than a measurement error. CONCLUSIONS: An accelerometer attached to the distal tibia is practical for use in a clinical environment to collect lower extremity acceleration data in children. Clinicians can utilise this technique for assessing a change following an intervention, such as biofeedback gait retraining.

Visual feedback gait re-training in overweight children can reduce excessive tibial acceleration during walking and running: An experimental intervention study.

BACKGROUND: Being overweight may increase the risk for developing stress fracture, as overweight adults and children were reported to have greater pressure peaks and rates under the heel during walking when compared with their normal-weight counterparts. Biofeedback gait retraining was shown to reduce ground impact magnitude in adults but not yet in children. RESEARCH QUESTION: The study examined whether overweight children have greater tibia peak positive acceleration (PPA) at ground impact during fast walking and running compared to healthy weight children, and whether visual feedback gait retraining program can be used to reduce PPA in overweight children. METHODS: Twenty five overweight and 12 healthy weight children participated in the study. Overweight children were randomly assigned into either feedback group or control no-feedback group of 8 sessions training program over 2-weeks. Tibia PPA at ground impact output from a wearable inertial sensor attached to the tibia was the feedback displayed on a monitor placed in front of the treadmill during walking and running. RESULTS: Compared to healthy weight children, overweight participants showed significant greater PPA values in running (p < 0.05), but not in fast walking. Feedback group significantly reduced PPA by 16% (p < 0.01), and these changes persisted at the 1-month follow-up. SIGNIFICANCE: Tibia PPA may be used in evaluating overweight children as a risk assessment to potential injuries due to high ground impact during running. Gait retraining using real-time feedback of tibia PPA may be useful in rehabilitation programs to reduce ground impact in overweight children.

Tibial impact accelerations in gait of primary school children: The effect of age and speed.

Tibial stress fractures are associated with increased lower extremity loading at initial foot-ground contact, reflected in high peak positive acceleration (>8g) of the tibia in adults. There is no reported data on peak positive acceleration of the tibia in children during walking and running. The aim of this study was to establish tibial peak positive acceleration responses in children across a range of age and gait speeds. Twenty-four children aged 8.5±1.4years with no known gait pathology comprised two age groups; Young (7-9year, n=12) and Older (10-12 years, n=12). Wireless Inertial Measurement Unit comprising a tri-axial accelerometer was securely taped to the anteromedial aspect of the distal tibia to measure peak positive acceleration responses while walking and running on the treadmill at 3 different speeds (20% below baseline, baseline, and 20% above baseline). Results showed significant increase in peak positive acceleration with increased gait speed and greater variability in young children compared to older children. The study suggests that ground impact in walking, but not running, is mature by age 7 years. Future studies should explore strategies using peak positive acceleration responses to monitor ground impact during sport activities and its application in gait retraining.