Recovery of Hormonal, Blood Lipid, and Hematological Profiles from a North Pole Expedition

Abstract

This study examined the recovery patterns of hormonal, blood lipid, and hematological profiles following strenuous physical loading, continuous extreme cold exposure and energy deficit induced by a North Pole expedition. Seven men completed an 850-km North Pole expedition in temperatures varying from -3 degrees C to -47 degrees C. Daily energy intake was approximately 23 MJ x d(-1) and was composed of approximately 60% fat. Blood samples were collected 2 wk before (Pre) the expedition and after 2 wk (Post 1), and 2 mo (Post 2). Additional samples were collected on the first (R1), third (R3), and fifth (R5) return days. Mean weight loss upon return was 10 kg. Energy expenditure was estimated to be 29.6 MJ x d(-1). Declines in cortisol (-237.29 nmol x L(-1)), total testosterone (-5.08 nmol x L(-1)), bioavailable testosterone (-0.37 nmol x L(-1)) and free thyroxin (-5.82 pmol x L(-1)) returned to normal values at R5 or Post 1 (P < 0.05). The increase in sex hormone-binding globulin (+17.5 nmol x L(-1)) rapidly returned to the pre-expedition concentration at R3 (P < 0.05). Significantly greater values were observed at Post 1 in the lipid (high-density lipoprotein +1.86 mmol x L(-1); low-density lipoprotein +4.23 mmol x L(-1)) and hematological (WBC +1.28 x 10(3)/L; platelets +51.86 x 10(3)/L) profiles (P < 0.05). RBC, hemoglobin, and hematocrit were all lower at Post 1 (P < 0.05). Although the expedition generated extreme physical stress, this was not directly reflected on hormonal recovery times as it was similar to other much less strenuous events. Despite important variations, all hormones returned to baseline values within 2 wk. Nonetheless, physical stress would appear to have more long-term effects on blood lipid and hematological profiles.