This recent study published in the Journal of Thermal Biology (2026) explores the relationship between brown adipose tissue (BAT), known as "brown fat" with a great thermogenic capacity, and different exercise modalities. Through the use of infrared thermography as a non-invasive assessment tool, researchers categorized trained individuals according to their basal BAT activity to observe how it influences energy expenditure and substrate oxidation during continuous aerobic exercise (AERO) and high-intensity interval training (HIIE). Analysis using regression models allowed for the capture of metabolic trajectories in real time, offering a detailed view of how our bodies manage energy not only during exertion but also in the crucial recovery phase.

The results reveal a key finding for exercise prescription: the exercise modality has a much more determinant impact on acute metabolism than basal brown adipose tissue activity alone. HIIE proved to be superior to aerobic exercise, generating significantly higher total energy expenditure and, most importantly, a much more pronounced lipid oxidation during the post-exercise phase. Although it was hypothesized that individuals with higher BAT activity would have a notable metabolic advantage, the data suggest that exercise intensity dominates the metabolic response, masking potential differences derived from BAT thermogenesis.

From an applied perspective, this study underlines the value of thermography for identifying physiological profiles and validating the efficiency of training protocols. The ability to monitor supraclavicular temperature allows sports and health professionals to segment users, although the main conclusion is universal: to maximize fat burning and metabolic efficiency after a session, high-intensity interval training is the most robust strategy. These findings invite the continued use of infrared technology to further investigate how factors such as fasting or cold combined with exercise could further awaken the metabolic potential of brown adipose tissue.

Key points for practice:

• Infrared thermography is a valid and non-invasive method for classifying brown adipose tissue activity in humans.
• High-intensity interval exercise (HIIE) generates significantly higher energy expenditure (+10-15%) compared to continuous aerobic exercise.
• Fat oxidation reaches its peak during recovery from HIIE, regardless of the individual's basal brown fat level.
• In trained subjects, the modality and intensity of exercise are the primary drivers of metabolic kinetics over basal physiological traits.
• The use of thermography allows for a personalized assessment that helps to better understand metabolic flexibility and individual response to trainingç

BIBLIOGRAPHY

Soto DAS, Pérez DIV, Almeida NR, Miarka B, Oyarzo AIA, Marins JCB, Sillero-Quintana M, Queiroz ACC, Brito CJ. Interactions between brown adipose tissue activity and exercise modality on metabolic kinetics: a crossover study in trained individuals. J Therm Biol. 2026 Feb;136:104392. doi: 10.1016/j.jtherbio.2026.104392. Epub 2026 Jan 18. PMID: 41564815.