A 7-segment numerical hand-glove/mitten model for predicting thermophysiological responses of the human hand in extremely cold conditions.

A 7-segment and 29-node numerical hand-glove/mitten model was developed to simulate human hand physiological responses in various cold environments. To validate the model, simulated skin temperatures were compared to data from published literature and human trials conducted at -20, -40, and -60 °C. Results demonstrated that the model could reasonably predict cold-induced vasodilation (CIVD) responses at 0 °C temperature. At -20 °C, the model predicted skin temperature with the root mean square deviation (RMSD) falling within the measurement standard deviation (SD) for both the entire and local hand except for the posterior hand. At -40 and -60 °C, the model could predict the trend of the skin temperatures of the whole/local hand, but the RMSD was larger than the SD for the majority of predictions. A parametric analysis revealed that the palm and posterior hand had higher skin temperatures than the fingers, while the thumb had the lowest skin temperature of the fingers in all simulated cases except the case with a 3.5 clo mitten at -60 °C. The proposed numerical hand-glove/mitten model could reasonably predict local hand physiological responses in three extremely cold environments and provides fundamental knowledge for cold stress prediction and protective glove development, thereby improving the safety and health of industrial workers, firefighters, first responders, and troops.

Duration limits for exposure for the whole body and extremities with a military extreme cold protection clothing ensemble at an ambient temperature of -40°C.

Manual performance and body temperature responses were assessed in a 1-h trial at an ambient temperature (TAMB) of -40°C for 7 male participants (32 ± 14 (mean ± SD) years) wearing a typical military extreme cold protection clothing ensemble. The purpose was to establish duration limited exposure (DLIM) for these conditions, and it was hypothesized that (i) core temperature (TCORE) would remain normothermic, whereas extremity skin temperature (TSK) would decrease; (ii) decrements of manual performance would be in proportion to decreases of hand TSK; and (iii) DLIM would be determined by the hand or foot TSK responses. Linear regression was employed to assess associations of manual performance scores and body temperatures with DLIM assessed using the Required Clothing Insulation (IREQ) model and extremity temperatures in ISO 11079-2007. Results showed TCORE remained at ~37.3°C, whereas there were significant (0.0001 < p < 0.05) decreases in extremity TSK. Associations between manual performance and hand TSK showed coefficients of determination (R2) ranging from 0.48 < R2 < 0.98; 0.00005 ≤ p ≤ 0.08. The DLIM for the whole-body ensemble ranged from 2.2 h to > 8 h, whereas the DLIM for the extremities was 0.56 ± 0.20 h for TSK decreasing 15°C. In conclusion, the hypotheses of a stable core temperature and decreases of extremity skin temperature giving decrements in manual performance were accepted as was the hypothesis that duration limits for exposure would be determined by extremity skin temperatures of the hand and foot.

Current Status of the Female Athlete Triad: Update and Future Directions.

PURPOSE OF REVIEW: This review provides an update on the primary clinical sequelae of the Female Athlete Triad. RECENT FINDINGS: Scientific advancements have contributed to improve understanding of Triad-related conditions, including leptin's role as a potential neuroendocrine link between energy status and reproductive function. Use of finite element analysis of HRpQCT imaging has provided a more accurate assessment of bone geometry and bone strength and may be clinically relevant. New perspectives aimed at developing and implementing a multi-disciplinary, personalized approach in the prevention and early treatment of triad-related symptoms are provided. The Female Athlete Triad is a multi-dimensional condition that affects active women across the lifespan. Energy availability impacts reproductive function and bone with implications for health and performance. Understanding the contributions of each individual component as well as their interconnected effects is necessary for progression and expansion of the Triad literature.