Sex Differences in Thermal Behavior During Exercise Recovery
Authors: Vargas Nicole T. , Chapman Christopher L. , Sackett James R. , Abdul‐Rashad Jabril , Johnson Blair D. , Gathercole Rob , Schlader Zachary J. 
Published: June 2021

PurposeFemales (F) more rapidly withdraw heat loss thermoeffectors post‐exercise compared to males (M), prolonging elevations in core temperature (Tcore). Thermal behavior may compensate for this response, but it is not known if thermal behavior differs between M and F. We tested the hypothesis that thermal behavior remains engaged post‐exercise for a longer time in F than M.MethodsIn a 24°C (43% RH) environment, 17 adults (9 F, 22 ± 2 y) cycled for 60 min, followed by 60 min seated recovery. Mean skin temperature (Tskin, 10 site), Tcore (intestinal) and mean skin wetness (wskin, 4 site) were measured continually. Subjects controlled the temperature of their dorsal neck to perceived thermal comfort using a custom made fluid filled device. Neck device temperature (Tdevice) provided an index of thermal behavior. A linear regression was performed with Tskin, Tcore, and wskin as independent variables and Tdevice as the dependent variable. Standardized beta coefficients were used to determine the relative contribution of each variable to Tdevice.ResultsMetabolic heat production did not differ between sexes during exercise (M: 133 ± 5, F: 123 ± 8 W/m2, P=0.40). Tskin (P=0.80), Tcore (P=0.97), wskin (P=0.76), and Tdevice (P=0.13) did not differ between sexes during exercise or recovery. During exercise, Tskin increased in F (Pre‐Exercise (PreEx): 29.6 ± 0.7°C; End‐Exercise (EndEx): 30.4 ± 0.6°C, P≤0.02), and decreased in recovery (End‐Recovery (EndRec): 29.7 ± 0.6°C, P≤0.01). Tskin did not change throughout in M (PreEx: 29.5 ± 0.6; EndEx: 30.0 ± 0.8, EndRec: 29.5 ± 0.7°C, P≥0.42). Tcore increased in F (PreEx: 37.3 ± 0.3, EndEx: 38.1 ± 0.2°C, P<0.01) and M (PreEx: 37.0 ± 0.3; EndEx: 37.5 ± 0.3°C, P<0.01) during exercise, remaining elevated until 40 min recovery (F: 37.5 ± 0.2, P=0.20; M: 37.3 ± 0.4°C, P=0.08). wskin increased in F (PreEx: 0.21 ± 0.06; EndEx: 0.25 ± 0.03 a.u., P=0.01) and M (PreEx: 0.17 ± 0.06; EndEx: 0.22 ± 0.05 a.u., P=0.03) during exercise, remaining elevated during recovery (F ‐ EndRec: 0.27 ± 0.04, P<0.01, M ‐ EndRec: 0.21 ± 0.05 a.u., P≤0.03). Tdevice decreased in F (Pre: 27.4 ± 0.9; EndEx: 6.1 ± 6.1°C, P≤0.01) and M (Pre: 27.3 ± 1.5; EndEx: 11.8 ± 10.5°C, P≤0.01) during exercise, returning to PreEx 20 min into recovery (F: 20.1 ± 8.0, P≥0.09; M: 19.1 ± 9.2°C, P≥0.06). During exercise, Tcore (51 ± 25%) contributed to Tdevice more than Tskin in M (13 ± 8%, P=0.05), but neither were different to wskin (36 ± 25%, P≥0.37). In F, Tcore (31 ± 26%), Tskin (35 ± 31%) and wskin (34 ± 24%) contributed equally to Tdevice (P≥0.98). During recovery, Tcore (55 ± 21%) contributed more than Tskin (17 ± 13%, P=0.02) in F, but neither were different to wskin (28 ± 20%, P≥0.15). In M, Tcore (37 ± 35%), Tskin (27 ± 23%) and wskin (36 ± 22%) contributed equally to Tdevice (P≥0.84).ConclusionsThermal behavior during and post‐exercise does not differ between M and F. However, Tcore contributes more to thermal behavior during exercise in M and post‐exercise in F. These findings may be related to temporal differences in Tskin during and following exercise.Support or Funding InformationSupported by lululemon athletica inc.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.