Nicholson et al 2011
Nicholson G, Loney T, Carter JM (2011). Physiological demands of military drill in army cadets from the United Arab Emirates. Presented at the 2nd International Congress on Soldiers’ Physical Performance. University of Jyväskylä, Finland.
INTRODUCTION Numerous studies have quantified the physiological demands of military physical training (MPT); however, a dearth of research exists investigating the physiological load elicited by military drill (MD). Therefore, the objective of this study was to investigate the physiological demands of MD in comparison to MPT and to quantify the contribution of MD to daily physical activity (PA). METHODS Fifteen adolescent cadets (age 15.6 ± 0.4 yr, body mass 57.2 ± 7.4 kg, stature 1.67 ± 0.05 m) were recruited from a Military Academy in the United Arab Emirates and monitored during three MD and two MPT sessions over a four week period. The MD sessions focussed on teaching cadets basic marching manoeuvres and formations, whilst the MPT sessions involved running and calisthenics to improve cardiorespiratory fitness and muscular endurance. All sessions were scheduled to last 60 minutes during which study participants wore a heart rate (HR) monitor (Polar Electro Oy, Finland), a three-dimensional accelerometer (3DNXTM; Biotel Ltd, Bristol, UK) positioned in the small of the back, and two hip-mounted (one left hip, one right hip) pedometers (Yamax Digiwalker, Tokyo, Japan) to estimate the physiological demands of each activity. Heart rate monitors and accelerometers were time-synchronised and set to record in 5 s epochs. During one of the MD assessment days participants wore all monitors for the entire waking day. Heart rate data were used to provide an index of cardiovascular strain using Percentage of Heart Rate Reserve (%HRR; Howley, 2001); 3DNXTM - derived activity counts (physiological stress) were utilised to quantify time spent in different PA intensities (i.e. light, moderate, vigorous) and time spent standing; additionally, step count data were obtained from pedometers. RESULTS Heart Rate Telemetry: Estimated cardiovascular strain was significantly lower during MD compared to MPT (mean %HRR 36 ± 6% vs. 41 ± 6%; P<.01), which corresponded to light (20-39 %HRR) and moderate activity (40-59 %HRR) according to Howley’s PA classification system (2001). Accelerometry: Estimates of time spent in both moderate- (15.2 ± 1.7 min vs. 19.6 ± 3.8 min; P<.001) and vigorous-intensity PA (2.2 ± 0.4 min vs. 9.7 ± 2.8 min; P<.001) were lower during MD compared to MPT; however, there were no significant differences between MD and MPT for time spent in light-intensity PA or standing (Figure 1). On non-MPT days, MD contributed 18% of total activity counts, in addition to 23% and 45% of time spent in moderate- and vigorous-intensity PA, respectively. Pedometry: Mean step counts were ~40% lower during MD than MPT (2557 ± 171 steps vs. 4073 ± 719 steps; P<.001) and there were no significant differences between left- and right-leg pedometer counts for any of the MPT sessions, or the waking day monitoring period (all P’s >.05). In contrast, left-leg pedometer counts were significantly higher than right-leg values for all MD sessions (mean 2603 ± 176 steps vs. 2512 ± 180 steps; P<.01). On non-MPT days, MD contributed 23% of total daily step counts.
Figure 1. Heart rate and accelerometer data for Military Drill (MD) and Military Physical Training (MPT)
DISCUSSION Heart rate and three-dimensional accelerometer data indicate that MD places a light-to-moderate physiological load on adolescent cadets. Although the physiological demands of a MD session are lower than a MPT session, military personnel should ensure that MD and MPT sessions are scheduled at opposite ends of the daily training programme (e.g. morning-evening) in order to minimise the stress placed on the lower limbs and reduce the risk of associated injury. REFERENCES Howley ET. 2001. MSSE, 33: S364-S369.
