The Impact of Load Carriage on Lower-Body Power in SWAT Police

Introduction:

Tactical personnel such as Special Weapons and Tactics (SWAT) police are required to carry occupational loads of approximately 20 kg and, on occasion, more than 40 kg. These occupational loads have been found to negatively impact officer mobility. The aim of this study was to investigate the impact of load carriage on lower-body power in SWAT Police.

Methods:

Six active male officers of a state police SWAT unit (mean age = 34.0 ± 7.4 years, mean height = 184.2 ± 3.3 cm, mean body mass = 96.3 ± 6.4 kg, mean years of SWAT experience = 6.0 ± 6.8 years) volunteered to participate. Ethics approval for the study was obtained by Bond University Human Research Ethics Committee (RO1585). Lower-body power was measured using a repeated vertical jump (VJ) test of three jumps with data collected using an uni-axial portable force plate sampled at 600 Hz and filtered using a 4^th order Butterworth filter with a cut-off frequency of 50 Hz. Force-time data were subsequently analysed. The VJ variables, peak velocity, peak force, peak power, and jump height and landing force were measured. Officers randomly completed the VJ in both an unloaded condition (5.5 kg – fatigues and M4 weapon slung) and a tactically loaded condition (23.5 ± 2.8 kg: 24.5 ± 3.4% body mass) with all operational equipment. The VJ heights of all three jumps were averaged to provide a final VJ height for analysis.

Statistics:

Paired sample t-tests were used to evaluate differences between the tests in loaded and unloaded conditions. Magnitude of differences was calculated according to Cohen’s effect size. Pearson’s correlations were conducted to investigate relationships between the unloaded and loaded condition for each variable. The significance level for all data was set at p < .05.

Results:

The results of the paired samples t-test revealed no statistical difference between the initial and third VJ height performed in the repeated VJ test, for either the unloaded (p = .864) or loaded (p = .898) conditions. There were significant differences (p < .001) between the unloaded and loaded conditions in VJ height (0.34 ± 0.02 m; 0.26 ± 0.02 m, respectively) and peak velocity (2.57 ± 0.07 m.s^-1; 2.26 ± 0.08 m.s^-1, respectively) with large effect sizes (d=-1.73 and -1.71 respectively). All measures, with the exception of landing force (r=.46, p=.35) were significantly and strongly correlated

Conclusion:

Lower body power in SWAT Officers is reduced during load carriage. This can potentially lead to decreased tactical performance in critical tasks, such as seeking, or moving between, cover. Officers should train in both unloaded and loaded conditions to increase lower body power and mitigate landing impacts.

Keywords: law enforcement, fitness, training, specialists