Vertical ground reaction forces in patients with unilateral plantar heel pain — a pilot study

Plantar heel pain (PHP) is a foot pathology commonly reported in both athletic and non-athletic populations. The etiology of PHP is complex and identification of risk factors associated with PHP is required to predict who is at increased risk of injury. Excessive plantar heel force and pressures are intrinsic risk factors that may play a contributing role in the development of PHP. Limited research, however, has been undertaken in terms of ground reaction forces associated with PHP. The aim of the study was to test the hypothesis that there were significant differences in the vertical ground reaction forces and loading rates at rearfoot contact between symptomatic and contra-lateral asymptomatic feet in 23 subjects diagnosed with unilateral PHP. The equipment consisted of a portable force plate using a 10-m modular walkway sampled at 200 Hz by an independent observer. Paired t-tests demonstrated no significant difference (P>0.05) in the vertical ground reaction forces and loading rates between the symptomatic and contra-lateral asymptomatic feet. The results suggest that single risk factors such as vertical ground reaction force and loading rates do not contribute to PHP. The authors conclude that a model that incorporates a multi-factorial approach to risk factors may lead to a better understanding into the etiology and management of those individuals who suffer from heel pathologies.