Long, Hot Summer: A Preliminary Investigation of Seasonal Variations in the Physical Fitness Performance Of Law Enforcement Recruits in Southern California

Law enforcement agencies (LEA) conduct physical testing to assess readiness of recruits prior to academy training. The LEA in this study uses a test battery called the Validated Physical Ability Test+ (VPAT+) on set dates during the year, typically performed outdoors. Warmer ambient temperatures can negatively affect physical performance via increased heat stress and decreased time to muscular fatigue. Differences in performance on these tests due to warmer temperatures could have implications for recruit performance. The purpose of this study was to determine whether seasonal differences in temperature impacted LEA recruit performance in their VPAT+ performance. Retrospective analysis was conducted on data from four classes, which encompassed 375 recruits from one LEA. The classes completed the VPAT+ during four different seasons (Fall (FALL): ♂ = 71, ♀ = 18, temp = 22-28°C, humidity = 20-32%; Winter (WIN): ♂ = 73, ♀ = 11, temp = 18-26°C, humidity = 8-11%; Spring (SPR): ♂ = 75, ♀ = 27, temp = 22-29°C, humidity = 23-50%; Summer (SUM): ♂ = 83, ♀ = 17, temp = 21-25°C, humidity = 39-71%). The VPAT+ occurred in the week prior to the start of academy and included: push-ups and sit-ups completed in 60 s; arm ergometer revolutions in 60 s; 75-yard pursuit run (75PR); seated medicine ball throw with an x kg ball (MBT); vertical jump (VJ); and multistage fitness test (MSFT). To compare groups, a one-way ANOVA was used with a Bonferroni post hoc (p < 0.05). There were significant differences between the seasons in certain VPAT+ tests. For push-ups, WIN and SUM performed 16% and 19% better than SPR, respectively. For the MBT, SUM performed 18% better than FALL. For the arm ergometer, SPR and SUM performed 8-9% better than WINTER, and SUMMER performed 11% better than FALL. WIN performed significantly better than SUM, SPR, and FALL in the MSFT, completing 18%, 27%, and 16% more shuttles. No significant differences were found in sit-ups and VJ. Variability in VPAT+ performance across the seasons could be due to class-to-class fitness variations in recruits. However, WIN was significantly better in the MSFT, which is a maximal running test. Warmer temperatures can increase cardiovascular strain, while humidity can decrease sweat evaporation rates. Both factors can result in an increased rate to fatigue and poorer performance on the MSFT. LEA staff may need to consider ambient temperatures and humidity during tests such as the VPAT+ due to potential negative effects on recruit performance, and this is particularly true for maximal running tests.