Edinburgh Napier University

  Introduction: The cyclic high impact loading forces and kinematics of British Army foot-drill suggest that foot-drill may contribute to the high incidence rates of lower-limb musculoskeletal (MSK) injuries reported in recruit populations. Transient adaptations in neuromuscular function and joint proprioceptive sensibility may exacerbate lower-limb MSK injury risk post an acute bout of physical activity. The relationship between British Army foot-drill training and the associated cyclic high impact (extended-knee) landings on measures of neuromuscular function and ankle joint proprioception has not been explained. Therefore, the aim of the present study was to examine changes in static and dynamic postural stability, and quantify potential differences in ankle joint proprioception in recruit-aged women at baseline, and pre–post an acute bout of British Army foot-drill training.

Methods: A within-participant repeated-measures study design was used to determine changes in static and dynamic postural stability, and ankle joint proprioception between events (baseline, pre and post). Fourteen healthy women (24.2 ± 2.3 yrs, 175.8 ± 4.8 cm, and 79.3 ± 6.3 kg) volunteered. A British Army drill instructor conducted all foot-drill sessions. The magnitude of joint position sense (JPS) error between events for 30% and 60% of full inversion range of motion, and 30% of full version range of motion quantified changes in ankle joint proprioception. Non-linear dynamic analysis (sample entropy) determined differences in static balance between two conditions, eyes open and eyes closed, while the dynamic postural stability index (DPSI) quantified differences in dynamic balance anterior–posterior (AP) and medio-lateral (ML) directions on landing.

Results: Greater mean JPS error (2.35°, p = .029) and DPSI scores for AP (0.38, p = 0.033) and ML (0.31, p = 0.039) were observed post foot-drill when compared to pre-test measures. Greater irregularity in static postural stability (0.23, p < 0.05) was observed post foot-drill when compared to pre-test measures, reflecting poorer static postural stability.

Conclusion: The results demonstrate impaired ankle joint proprioception and static and dynamic postural stability. The effects of an acute bout of foot-drill training and the associated changes/impairments in proprioception and neuromuscular function may contribute to specific lower-limb MSK injury as JPS and postural stability are recognised as predictors of lower-limb MSK injuries/disorders.