LAUSR

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.