Analysis of the Center of Mass and Center of Pressure in Typically Developing Children During Heel-Toe Gait and Toe Walking
Lindsey Adelstein, SPT; Mary Claire Hartford, SPT, CSCS; Bernadette Javier, SPT;
Rachel Kern, SPT; Marley Owen, SPT; Kerryn St. Andre, SPT
Research Advisors: Kathleen Schlough, PT, DSc, PCS; Deborah King, PhD;
Stephen Lahr, PT, PhD
ABSTRACT
Introduction: Toe walking gait typically normalizes by 3 years of age, and is seen in 7-24% of children. Idiopathic Toe Walking (ITW) is diagnosed when other conditions are ruled out. While literature has noted changes in ankle kinematics for children with ITW, there is no evidence on how the center of mass (COM) and center of pressure (COP) positions change. The angle between the COM and COP (COM-COP angle) determines how the body maintains balance during gait, and by changing their positions during toe walking children may alter the way they maintain upright. The hypothesis is that the angle will decrease in the sagittal plane in toe walking as compared to heel-toe gait. This research works to fill the gap on differences in COM and COP positioning during heel-toe gait and toe walking.
Methods: Children aged 3 to 6 were recruited for an observational study via word of mouth and assessed using VICON® 3D motion capture system and 4 force plates. Reflective markers were placed on specific bony prominences. Children walked with heel-toe and toe walking pattern across force plates. Three successful trials of each pattern were collected. Data collected was filtered into Visual 3D software for analysis. COM was calculated based on predicted values and individual anthropometric data. COP was determined at initial contact (IC) and pre-swing (PS) for each gait pattern. The COM-COP angle in the sagittal plane at IC and PS was calculated. Independent t-test was used to analyze the differences in the COM-COP angle at IC and PS between heel-toe gait (HT) and toe walking (TW).
Results: Data was analyzed from 14 (9 males and 5 females) participants, aged 3.5- 6.75 years. COM-COP angle at IC and PS was measured during both HT and TW. Independent t-test was used to compare averages of the COM-COP angle at IC and PS during HT and TW at an alpha level of 0.05. The average angle at IC during HT was 15.5° and TW was 17.3°. The p-value was 0.14. The average angle at PS during HT was -17.8° and TW was -16.8°. The p-value was 0.17. Percent change was calculated for each participant at IC and PS between HT and TW. These values ranged from an increase of 2.7% to 95.1% and a decrease of 0.5% to 47.1%.
Discussion: The principal finding was that the COM-COP angles at IC and PS were not statistically significant between HT and TW. Generally, there was a trend towards an increased angle at IC and decreased angle at PS during TW. This suggests a consistent change in biomechanical position during TW and therefore an alternative method to maintain upright when TW compared to typical gait. More research is needed to investigate muscle activity during TW to further support a change in how a child maintains their balance. Limitations include inconsistent gait speed and gait patterns. Strengths include high quality data capture, consistency of examiners, and detailed data analysis protocol.
Conclusion: There is potential for biomechanical change proximal to the ankle during TW. It is recommended that clinicians look at more than the ankle and examine the whole body during evaluation of children who habitually toe-walk.