Infrared Thermography (IT) is a tool for the investigation of physiological functions through changes in blood flow that are associated with the control of Skin Temperature (Tsk). Tsk depends on extrinsic factors, such as environmental temperature and humidity; and intrinsic factors, such as anthropometric characteristics, circadian rhythm, age and sex. Sex, menstrual cycle, use of exogenous hormones, subcutaneous fat, and metabolic rate can affect female Tsk. Although there are already studies that relate temperature to body fat percentage, there are few inconclusive studies that correlate body composition with skin temperature by specific area.

To correlate skin temperature and body composition by body segments of women in the physiological menstrual cycle, use of exogenous hormones, and menopause.

This is a prospective observational study, Participants were 45 volunteers equally allocated into three groups: Exogenous Hormone Group (EHG) [24.53±4.30 years, 58.59±8.46kg, 161.13±6.67cm] Physiological Menstrual Cycle Group (PMCG) [26.33±4.83 years, 58.12±10.02kg, 161±5.53cm] and Menopause Group (MG) [57.13±8.79 years, 68.76±15.82kg, 157±7.16cm]. The EHG volunteers use combined oral contraceptives, while the others did not use any other type of medication or hormonal supplementation. To control the circadian rhythm and the phase of the menstrual cycle, all of them underwent segmental body composition measurements (muscle mass and fat in kilograms) using an InBody 120 bioimpedance scale, and skin temperature measurements were made using a FLIR model T-360 camera once a week, at the same time, over a 28-day period. The areas of interest were the breast region, abdomen, trunk, lumbar spine, breech, upper and lower limbs. For correlation analysis between skin temperature and body composition a Pearson correlation test was performed using SPSS, version 21.

There was no significant correlation (P>0.05) between muscle mass and skin temperature of the evaluated areas in any of the groups or evaluation times. Regarding to body fatness, it was observed that independently of the phase from the menstrual cycle, the PMCG presented a negative correlation between temperature and trunk fatness (r= -0,780, P<0,01) and between upper limbs fatness and breast temperature (r= -0,655, P<0,01) and abdomen (r= -0,638, P<0,01).The EHG group showed significant negative correlations between body fat and temperature of breast (r=-0,712, P<0,01), abdomen (r= -0,701, P<0,01), posterior trunk (scapulae region) (r=-0,680, P<0,01), right lower limb (r= -0,672, P<0,01) and upper limbs (r=-0,686, P<0,01). The MG showed only negative correlation (r=-0,591, P<0,01) between fat and skin temperature of the posterior trunk.

Skin temperature has an inverse relationship with fatness of the assessed region, while resting muscle mass has little impact on the distribution of skin temperature in women at different stages of life.

The study shows the need to consider anthropometric characteristics when analyzing skin temperature by IT.