Reliability of the Kinetics of British Army Foot Drill in Untrained Personnel

Abstract

Rawcliffe, AJ, Simpson, RJ, Graham, SM, Psycharakis, SG, Moir, GL, and Connaboy, C. Reliability of the kinetics of British Army foot drill in untrained personnel. J Strength Cond Res 31(2): 435-444, 2017-The purpose of this study was to quantify the reliability of kinetic variables of British Army foot drill performance within untrained civilians and report the magnitude of vertical ground reaction force (vGRF) and vertical rate of force development (RFD) of foot drills. Fifteen recreational active males performed 3 testing sessions across a 1-week period, with each session separated by 24 hours. Within each testing session participants (mean ± SD; age 22.4 ± 1.7 years; height 177 ± 5.6 cm; weight 83 ± 8.7 kg) completed 10 trials of stand-at-attention (SaA), stand-at-ease (SaE), Halt, quick-march (QM) and a normal walking gait, with vGRF and vertical RFD measured on a force plate. Between-session and within-session reliability was calculated as systematic bias, coefficient of variation calculated from the typical error (CVte%), and intraclass correlation coefficient (ICC). Significant (p ≤ 0.05) between-session differences were found for the vGRF SaA and SaE, and vertical RFD SaA and SaE conditions. Significant (p ≤ 0.05) within-session differences were found for the vGRF SaA and SaE conditions. A mean vGRF CVte% ≤10% was observed across all foot drills. However, the mean vertical RFD CVte% observed was ≥10% (excluding SaE) across all foot drills. The ICC analyses indicated that the vGRF Halt, QM, SaA, and Walk condition achieved moderate to large levels of test-retest reliability, with only SaE failing to achieve an ICC value ≥0.75. The vertical RFD QM, SaE, and Walk condition achieved moderate levels of test-retest reliability, with Halt and SaA failing to achieve an ICC value ≥0.75. It was determined that a single familiarization session and using the mean of 8 trials of vGRF are required to achieve acceptable levels of reliability.

The Effects of British Army Footwear on Ground Reaction Force and Temporal Parameters of British Army Foot Drill

“…The unique landing techniques of foot-drill combined with the lack of shock absorbing capabilities of standard issue footwear, namely the CB and AB, typically present high vertical RFD. Results of the present study are similar to those reported previously 4,7,24 The greater forces and shorter TTP of QM have been linked to the effective mass of the stamping…”

“…The magnitude of specific vGRF parameters representative of foot-drill, irrespective of the type of footwear worn, may be a contributing risk factor in the development of lower-limb MSK overuse injuries within recruit populations 4,24 . To date, only three studies have investigated the impact loading forces of foot-drill whilst wearing training shoes 6,24 and defender combat boots 4 ; reporting peak vGRF [range = 1.3 -5.1 bodyweights] [BWs] and peak vertical RFD [range = 67.6 -536 bodyweights/second] [BWs/s] values similar to, and in some cases greater than those observed for high level plyometric exercises 2,29 . The primary objective of these studies was to quantify vGRF parameters of foot-drill, and did not directly consider the potential influential factors associated with standard issue footwear on impact loading forces of foot-drill.…”

“…Each participant performed a standardised 10-min warm up consisting of dynamic lower-limb bodyweight exercises, namely, variations of the lunge and bilateral squat. Preceding the collection of foot-drill vGRF and temporal data, a single familiarisation session was conducted on the first day of testing, whereby each participant performed ten trials of each foot-drill 24 . Post familiarisation and a 15min recovery period, a total of eight trials per foot-drill were collected, as it has been demonstrated that a minimum of eight-trials is required to produce accurate and stable levels of foot-drill vGRF data [CVte% <10%, ICC > 0.75] 24 .…”

Intersession Reliability and Within-Session Stability of a Novel Perception-Action Coupling Task

“…This is especially troublesome given that several studies assessing the reliability of motor pattern or performance metrics (i.e kinematics, single-leg squat performance) have reported significant systematic bias due to a between-sessions effect. 8,32,38 These studies have all shown significant differences between the first session and all following sessions, indicating the need for a full familiarization session.…”

“…Therefore, the purpose of this study was threefold: to (1) establish the extent of any systematic bias between testing, (2) examine the test-retest reliability, and (3) determine the within subject variability associated with the PACT outcome data. Several previous studies on the reliability of behavioral measures have demonstrated significant betweensession, systematic bias 8,32,38 , thus it was included in this study, despite being absent from most research investigating the reliability of reaction time measures.…”