Cardiovascular and Thermal Responses to Cold Exposure during Exercise in Iron Deficient Anemic Individuals

Background/Objective: Temperature regulation is impaired in iron deficient anemic humans and rats at rest during cold exposure. However, there is a paucity of data regarding the interplay of cold exposure, anemia and exercise on thermal and cardiovascular responses. Therefore, we aimed to explore thermal and cardiovascular responses of individuals with chronic mild iron deficient anemia during exercise in the cold compared to controls. Methods: Nine anemic (5 F, 4 M) and 9 control (5 F, 4 M) individuals, matched for body fat, size, mass but different by design in hematological parameters and physical fitness, participated in the study. The participants cycled in cold (11 °C, 40% RH) and neutral (22 °C, 40% RH) conditions at an intensity ~10% below the respiratory threshold until 1 °C increase in Tre or 1h exercise, whichever occurred first. Results: In the cold, the anemic individuals showed a lower rate of Tre rise compared to controls (p=0.047) and only controls increased heat production (V̇O2) compared to the neutral condition (p=0.035). Moreover, in the cold, the anemic group exhibited lower Tsk than controls (p=0.03) and exaggerated blood pressure response compared to the neutral environment (p<0.05) due to heightened total peripheral resistance (p<0.05) and vasomotor response (p<0.001). Conclusions: In summary, chronic mild iron deficient anemia impaired temperature regulation as judged from the lower rate of Tre rise and an inability to activate further the metabolism at cold. Concomitantly, the anemic participants demonstrated increased cardiovascular strain. This is notable because anemia and these environmental conditions are encountered in the workplace, recreational activities and athletic endeavors.