The Effect of Heat Stress on Measures of Running Performance and Heart Rate Responses During A Competitive Season in Male Soccer Players
Measures of running performance (RP) and heart rate responses (HR) to matchplay during three different heat stress (HS) conditions were assessed in seven National Collegiate Athletic Association (NCAA) Division I male soccer players. Total distance (TD), as well as distance covered within distinct velocity zones [walking (WALK), jogging (JOG), low speed running (LSR), high-speed running (HSR), sprinting (SPRINT), low-intensity running (LIR), and high-intensity running (HIR)] were assessed using GPS units over 12 matches. HS was monitored during each match, and matches were defined as low (HSlow, n=4), moderate (HSmod, n=4), or high (HShigh, n=4) HS. Minutes played were significantly different across HS conditions (p=0.03). Therefore, distance covered within each movement velocity was assessed relative to minutes played, and as a percentage of total playing time. WALKrel was significantly greater during HShigh compared to HSlow (p=0.035). LIRrel was significantly greater during HSmod (p=0.015) compared to HSlow. A trend was observed for %WALK being higher during HShigh compared to HSlow (p=0.066). %LIR was significantly greater during HShigh compared to HSlow (p=0.048). HIR was not significantly different across HS conditions. Percent of time spent >85% HRmax was significantly greater during HShigh (p=0.002) and HSmod (p<0.001) compared to HSlow. Percent of time spent between 65-84% HRmax was significantly greater during HSlow compared to HShigh (p<0.001). Results indicate that HS resulted in increased LIR and %HR≥85, while HIR was maintained. HIR performance may be conserved through decreased playing time and/or the adoption of pacing strategies. This may assist coaches in altering player management strategies to optimize team performance.