Altered dynamic postural stability and joint position sense following British Army foot-drill

Impaired proprioceptive acuity negatively affects both joint position sense and postural control and is a risk factor for lower-extremity musculoskeletal injury in athletes and military personnel. British Army foot-drill is an occupational military activity involving cyclical high impact loading forces greater than those observed in athletes during high level plyometrics. Foot-drill may contribute to the high rates of lower-extremity overuse injuries observed in recruits during basic training. There is limited research investigating foot-drill specific injury risk factors in women. This study aimed to quantify changes in ankle joint proprioception and dynamic postural stability following a period of British Army foot-drill. Fourteen recruit age-matched women underwent pre-post foot-drill measures of frontal plane ankle joint position sense (JPS) and dynamic postural stability using the dynamic postural stability index (DPSI). Passive ankle JPS was assessed from relative test angles of inversion (IN) and eversion (EV) 30% and IN60% using an isokinetic dynamometer. The DPSI and the individual stability indices (medio-lateral [MLSI], anterior-posterior [APSI] and vertical [VSI]) were calculated from lateral and forward jump-landing conditions using force plates. Foot-drill was conducted by a serving British Army drill instructor. Significantly greater absolute mean JPS error for IN30% and EV30% was observed post foot-drill (p ? 0.016, d ? 0.70). For both the lateral and forward jump-landing conditions, significantly greater stability index scores were observed for MLSI, APSI and DPSI (p ? 0.017, d ? 0.52). Significantly greater JPS error and stability index scores are associated with the demands of British Army foot-drill. These results provide evidence that foot-drill negatively affects lower-extremity proprioceptive acuity in recruit age-matched women, which has implications for increased injury risk during subsequent military physical activity, occurring in a normal training cycle

Changes in Physical Performance during British Army Junior Entry, British Army Standard Entry, and Royal Air Force Basic Training

Introduction: To quantify changes in physical performance in men and women during British Army Junior Entry (Army-JE), Standard Entry (Army-SE), and Royal Air Force (RAF) Basic Training (BT). Design: Prospective longitudinal study. Methods: 381 participants [(339 men, 42 women) n=141 Army-JE; n=132 Army-SE; n=108 RAF] completed a 2-km Run, Medicine Ball Throw (MBT) and isometric Mid-Thigh Pull (MTP), pre- and post-BT. To examine changes in pre- to post- BT physical test performance, for each course, paired students t-tests, and Wilcoxon tests were applied to normally and non-normally distributed data respectively; with effect sizes reported as Cohen’s D and with rank biserial correlations, respectively. A one-way between-subjects ANOVA (or Welch ANOVA for non-normally distributed data) compared performance between quartiles based on test performance pre-BT. Where the main tests statistic, p value and effect sizes identified likely effect of quartile, post-hoc comparisons were made using Games-Howell tests with Tukey’s p value. Data are presented as mean ± standard deviation, statistical significance set at p<0.05. Results: During BT, 2-km run time improved by 13±46 (-2.1±8.1%), 30±64 (-4.8±12.3%), and 24±27 s (-4.5±5.1%) for Army-JE, Army-SE, and RAF, respectively (all p<0.005). MBT distance increased by 0.27±0.28 m (6.8±7.0%) for Army-JE (p<0.001) and 0.07±0.46 m (2.3±10.9%) for Army-SE (p=0.040), but decreased by 0.08±0.27 m (-1.4±6.0%) for RAF (p=0.002). MTP force increased by 80±281 N (10.8±27.6%) for Army-JE (p<0.001) and did not change for Army-SE (-36±295 N, -0.7±20.6%, p=0.144) or RAF (-9±208 N, 1.0±17.0, p=0.603). For all tests and cohorts, participants in the lowest quartile of pre-BT performance scores demonstrated greater improvements, compared with participants in the highest quartile (except Army-JE MBT; ∆% change similar between all quartiles). Conclusions: Changes in physical performance were observed for the three fitness tests following the different BT courses, but recruits with the lowest strength and aerobic fitness experienced greatest improvements