Thermography and fatigue: during a 10 days taper period in sprinters
Knowing the fatigue produced by different training stimuli, especially to select the best recovery strategies, will help to optimize performance.
The phenomenon of fatigue is multifactorial and affects different systems. Attempts have been made to explain fatigue by descending mechanisms from the nervous system’s control to how the muscle is affected peripherally. These models explain the decrease in the contraction signal produced by the brain to a depletion of the main energy substrates in the muscle that leads to exhaustion of the system.
Although these models provide information about the greatest limitation of exercise, they explain in a superficial way what happens in the hours or even days after a strenuous exercise and how we can improve recovery processes from the fatigue that has occurred.
Therefore, understanding the relationship between skin temperature, in different training or competition scenarios, with fatigue that manifests itself both acutely and chronically can help us select the best recovery methods.
To this end, Korman et al (2021) studied the effects of a 10-day training camp on short-distance runners from the Polish athletics team, including 8 women and 9 men.
The 17 elite athletes gathered in Monte Gordo (Portugal) to carry out an intensive 10-day preparation in a congested training schedule. In it, the relationship between these two variables to control the training load was studied by means of capillary blood tests to measure the concentration of creatine kinase and thermographic analysis tests to evaluate body temperature.
The tests were carried out in the morning in a basal state and in the afternoon after completing the training sessions. Therefore, they had two measurements. In addition, the evaluation made of body temperature was the mean of the temperature of the anteroinferior and posteroinferior protocols. (In this sense, ThermoHuman points out that the data could be improved with the selection of better variables extracted from thermography)
The training process during those 10 days is shown in Figure 1.
Figure 1. Training contents during the training camp.
The results show a significant decreasing trend in body temperature during the days of the training camp. While for the CK values, there is an incremental trend concurrent to the training blocks. (Figure 2)
In addition, the authors made an approximation to assess where the greatest temperature change occurred if during the day (that is, they subtracted the values in the morning from those obtained in the afternoon) or at night (that is, they subtracted the values in the afternoon to those obtained the following morning) with this they verified the effect of the circadian rhythm, reaching the conclusion that the best time to carry out the data collection is in the morning in a basal state.
From ThermoHuman we carefully analyzed this study to support the hypothesis of the use of thermography to analyze the state of fatigue in athletes with the aim of prescribing the best strategies for optimizing recovery, which was also discussed by Robin Thorpe in his article in 2021 on the options to choose to optimize recovery.
The relationship between thermography and the CK variable has been investigated in the scientific literature with inconclusive results. In a systematic review (dos Santos et al 2022), the authors point out that the variables cannot be related, although this does not mean that there is no correlation, but that it may only exist under certain contexts (after a competitive load), or in very specific regions after a specific stimulus. It seems that CK is not as responsive as skin temperature to identify the different types of fatigue.
These results support the idea that a state of central fatigue produced by the increase of a repetitive, congested, and intense load in a short period of time will produce a decrease in body temperature. While if the stimulus is adaptive, the normal response to tolerance to training should be hyperthermic or normothermic within confidence levels.
Although we point out that more research is needed to support this hypothesis.
Korman, P., Kusy, K., Kantanista, A., Straburzyńska-Lupa, A., & Zieliński, J. (2021). Temperature and creatine kinase changes during a 10d taper period in sprinters. Physiological Measurement, 42(12), 124001.
Thorpe, R. T. (2021). Post-exercise recovery: Cooling and heating, a periodized approach. Frontiers in Sports and Active Living, 3, 707503.
dos Santos, T. M., dos Santos Bunn, P., Aidar, F. J., Mello, D., & Neves, E. B. (2022). Correlation between creatine kinase (CK) and thermography: a systematic review with meta-analysis. Motricidade, 18(3).