| description abstract | Abstract. Thermography of the breast offers noninvasive insight into vascular and metabolic activity, yet data on the influence of reproductive hormones and exercise on surface temperature remain limited. A longitudinal study of five healthy, regularly menstruating women was conducted over one complete cycle (∼30 days), measuring daily first-morning urine for estrone-3-glucuronide (E3G), pregnanediol-3-glucuronide (PdG), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) via Mira fertility kits. Resting breast temperature was captured biweekly using infrared (IR) imaging and nine skin-mounted thermistors at standardized positions. Weekly exercise sessions entailed 20 min at 80–90% age-predicted maximal heart rate, with thermal recordings taken every 30 s for 10 min postexercise. Resting temperature varied significantly across cycle phases, with progesterone (PdG) emerging as the strongest hormonal predictor, although mixed-effects models indicated that individual baselines dominated. Exercise unexpectedly induced a small but consistent surface cooling that resolved within approximately 10 min. Hormone-based models poorly predicted postexercise thermal changes, underscoring the transient nature of thermoregulatory responses. These results delineate distinct hormonal and exercise-induced breast thermal signatures, highlight inter- and intra-individual variability, and inform the personalized calibration of wearable thermographic systems and the timing of clinical scans, particularly by accounting for progesterone-driven luteal warming and short-term cooling from exercise. | |
