The effects of external loads carried by police officers on change of direction tasks

Police officers are often required to carry additional loads in the field. Current literature has observed that these loads reduce agility performance, but more investigation is required to understand the effects of load carriage on repeated change of direction and fatigue. This study aimed to examine the effects of load on repeated change of direction and examine the differences that absolute and relative load carriage have on fatigue levels in police officers. Forty-eight officers (mean age 39.06±8.11, mean height 176.90±8.41 cm, mean weight 87.18±16.99 kg) completed a timed 6x20 metre figure eight course wearing their daily duty loads (9.55±0.95 kg). Fatigue was measured by two formulas and statistical analysis examined correlations between body weight, absolute loads, relative loads, fatigue levels, and lap completion time. There was no significant correlation between absolute external load and any laps of the course, nor was there a correlation between fatigue levels or any other variables of the participants. Relative load had an impact on participants’ ability to complete a 180° turn after a 20-metre linear sprint. The researchers found a mean significant increase of 23% (1.06±0.28 seconds) in lap completion time when the participants changed from a 20-metre linear sprint to the 20-metre figure eight course, suggesting that initiation of change of direction experiences a greater setback the more relative load the officer is carrying. In addition, the body weight of the officer was associated with their ability to accelerate and complete the initial 20-metre sprint. These findings are of importance in preparing officers to pursue a suspect in regards to the initial acceleration and ability to change direction following a linear sprint.