The evolution of professional football in recent years has been marked by a drastic increase in high-intensity actions, which are decisive for competitive success and critical moments near the opponent's penalty area. While Global Positioning Systems (GPS) have established themselves as the standard tool for quantifying this external load, these metrics alone fail to capture the internal physiological response of the players. In response to this limitation, recent research has explored the use of Infrared Thermography (IRT) as an objective and non-invasive marker to evaluate physiological status and recovery following competitive effort.

The longitudinal study was conducted with twenty-four players from a Russian Premier League team across fourteen official regular-season matches. Researchers applied thermography protocols between 24 and 36 hours before and after each match, specifically analyzing the posterior chain regions of the lower limbs. The primary objective was to determine how High-Speed Running (HSR) volume and total distance traveled influence the relative change in skin temperature ($Delta T$), providing deeper insight into the neuromuscular impact of competition.

The results revealed that high-speed running is the most significant mediator of the post-match thermal response, surpassing the influence of total distance. Players classified in the "high load" group—those exceeding $372~m$ of $HSR$—demonstrated significantly greater decreases in skin temperature compared to those with lower intensity efforts. This finding suggests that the metabolic and mechanical stress derived from sprints at speeds over $21~km/h$ alters thermoregulation processes in a way that fatigue accumulated from running volume alone cannot replicate with the same magnitude.

Within the analyzed thermal profile, the hamstring region stood out as the most sensitive and reactive zone to high-intensity demands. For players in the high $HSR$ group, this area showed a temperature drop with a moderate-to-large effect size, correlating with the high neuromuscular demand these muscles endure during acceleration and maximal sprint phases. Interestingly, although a total distance exceeding $9675~m$ also showed some association with changes in the hamstrings, its practical and statistical relevance was notably lower than that of high-speed metrics.

From a physiological perspective, this reduction in skin temperature following high $HSR$ exposure could be linked to the depletion of energy substrates and specific patterns of neuromuscular fatigue affecting the metabolic and nervous systems. Unlike other aerobic stimuli that typically increase temperature in the following days, elite football generates a unique impact where the intensity of effort conditions a negative thermal response. These data underscore that internal monitoring through thermography should not be performed generically, but rather by attending to the specific workload of each individual on the pitch.

For coaching staffs and performance specialists, the incorporation of infrared thermography represents a critical advancement in the individualization of training loads during congested microcycles. The ability to detect significant thermal variations, especially in the hamstrings, offers an objective criterion to contextualize each player’s recovery and adjust physiotherapy or rest interventions. Ultimately, skin temperature positions itself as a key variable within athlete monitoring systems, allowing for the interpretation of the true cost of high-intensity movement patterns beyond what GPS screens display.