Thermography, Ammonia, and Lactate in Elite Athletes

Are there differences between disciplines? Is there any relationship between temperature and biomarkers? Does body composition influence the results?

We present a recent article by Korman et al. (2024), in which one of our Thermohuman members, Dr. Manuel Sillero Quintana, participated. This research examined variations in skin temperature and key biomarkers (lactate, ammonia) in elite athletes during and after exercise.

Markers and athletic performance

Understanding the optimal physiological parameters linked to exercise intensity and recovery efficiency in highly trained athletes is a crucial matter. Two of the most studied biomarkers are lactate (LA) and ammonia (NH3), used as key indicators in various types of exercise.

Lactate is formed under oxygen-deficient conditions during adenosine triphosphate (ATP) generation, serving as a marker of anaerobic metabolism and muscle fatigue during exercise. On the other hand, blood ammonia is generated as a product of adenosine monophosphate (AMP) breakdown, acting as an extracellular marker of ATP reserves in skeletal muscle. Both biomarkers, along with the rate of their utilization, are essential for understanding what occurs during the training process.

Thermoregulation during exercise is manifested, among other things, by changes in skin temperature. These changes vary depending on the type of physical effort, with different patterns observed in endurance and strength exercises. The relationship between body composition, particularly body mass index (BMI), and temperature emerges as a crucial factor. A lower BMI is associated with higher skin temperature, and vice versa.

However, many questions remain unresolved, and further exploration of the relationship between these indicators during exercise is needed. This was precisely the subject of study for Korman et al. (2024).

Study published in the prestigious journal Nature

This experimental study was conducted with elite athletes. It involved 22 highly trained male athletes, divided into speed athletes (n = 11) and endurance athletes (n = 11), all members of the Polish national teams.

The main procedures included repeated blood sampling and measurement of skin surface temperature at rest, during a progressive exercise test, and during a 30-minute recovery period.

Example of thermal response during the entire protocol proposed (A = anterior view and B = posterior view)

The following variables were recorded:

• Anthropometric and physiological measurements
• Exercise test and respiratory parameters
• Thermographic measurement (with IR FLIR SC640)
• Blood sampling and lactate and ammonia analysis

During the incremental exercise test, treadmill speed increments were conducted, with blood samples taken at the end of each increment. The achievement of maximal oxygen consumption (VO2 max) was considered under pre-established criteria. Additionally, other parameters such as respiratory and heart rate were monitored throughout the entire test.

Main results:

In the study, differences were observed in lactate (LA) and ammonia (NH3) levels in sprint and endurance athletes during an exercise test. Sprinters exhibited higher lactate levels and a linear relationship in its increase, while endurance athletes showed a slower increase. There were no significant differences in NH3 levels between the groups, but the increase was slower in the final phase of the test for endurance athletes.

Results during the incremental treadmill exercise test to exhaustion (Max) and during recovery in endurance athletes and sprint athletes – you can see it in the infographic.

This study is pioneering in tracking changes in skin temperature and biomarkers (LA, NH3) in highly trained athletes during incremental exercise and recovery. We found that the pattern of change in skin temperature and LA is linked to the training profile, with endurance athletes showing lower skin temperature at the end of exercise and a slower increase in LA levels. The positive relationship between skin temperature and LA during exercise is reversed during recovery, where higher skin temperature is associated with lower LA levels. Additionally, skin temperature was positively correlated with lean mass and inversely correlated with body fat.

The differences between endurance and sprint athletes indicate specific adaptations. The relationship between skin temperature and body composition suggests that those with more muscle mass and less fat have better thermoregulation.

The correlation between skin temperature and LA during exercise supports the efficiency of blood redistribution in highly trained individuals. During recovery, higher skin temperature levels are associated with lower LA concentrations, indicating rapid blood transfer to the skin. Although the methodology does not allow for establishing causality, these findings suggest that training status could be estimated through changes in skin temperature and LA, focusing on thermoregulation capacity and specific metabolic adaptations.

Conclusions:

• During exercise, the skin of the limb cools down and then reheats during recovery.
• Subjects with higher aerobic capacity experience less decrease in skin temperature during exercise and more increase in temperature during recovery.
• Athletes with lower body fat dissipate heat from their tissues more efficiently.
• There is a suggested correlation between skin temperature and lactate.

References

Korman, P., Kusy, K., Straburzyńska-Lupa, A., Kantanista, A., Quintana, M. S., & Zieliński, J. (2024). Response of skin temperature, blood ammonia and lactate during incremental exercise until exhaustion in elite athletes. Scientific Reports, 14(1), 2237.