New research from Georgia Southern University released on June 1 examines how the body’s response to preseason football training varies depending on an athlete’s position and injury status. The study, published in the International Journal of Sports Physiology and Performance, was led by Andrew Flatt, Ph.D., associate professor in Georgia Southern’s Department of Health Sciences and Kinesiology, with collaborators from the University of Alabama.
Heart-rate variability (HRV), which measures variation between heartbeats, is commonly used to assess how athletes respond to physical stress. Stable HRV from day to day indicates good adaptation to increased training loads.
Researchers monitored 27 players from a Division I national championship-winning program during preseason camp. They found that skill position athletes such as wide receivers and defensive backs showed more stable HRV patterns as workloads increased. These players are typically smaller and more aerobically conditioned, which may help them better handle intense running demands and heat.
In contrast, hybrid positions like linebackers, running backs, and tight ends—who experienced the highest workloads—showed greater daily fluctuations in HRV. The researchers said these athletes are often larger with lower aerobic fitness levels and could experience greater cardiovascular strain during intense training sessions in hot conditions. The findings suggest that moderating total workloads for hybrid position players may reduce fatigue and improve recovery rates during camp.
The study also examined injury effects by categorizing players as “full go” or “go as can.” While minor injuries did not significantly limit on-field workload, affected players showed moderately lower HRV levels than fully healthy teammates. This suggests even minor injuries can increase physiological stress during recovery.
The researchers said their findings highlight the importance for coaches of monitoring daily changes in HRV rather than relying solely on single scores. Tracking these changes can help identify fatigue or recovery challenges early, they said. They concluded that personalized training strategies based on cardiovascular responses may help optimize player performance throughout the season.
