ERYTHROPOIETIN IN 29 MEN DURING AND AFTER PROLONGED PHYSICAL STRESS COMBINED WITH FOOD AND FLUID DEPRIVATION

The study investigated the influence of prolonged physical stress duri ng survival training with food and fluid deprivation on the serum conc entrations of erythropoietin (EPO). A group of 29 male subjects [mean age 22.2 (SD 2.8) years, height 1.78 (SD 0.06) m, and body mass (m(b)) 73.5 (SD 8.6) kg] were studied for 5 days of multifactorial stress in cluding restricted water intake (11 H2O . day(-1)) and food intake (62 8 kJ . day(-1)) combined with physical exercise (estimated energy expe nditure approximately 24000 kJ . day(-1)) and sleep deprivation (20 h within 5 days). flood samples were taken before (T1), after 72 h (T2) and 120 h (T3) of physical stress, and after 48 h, (T4) and 72 h (T5) of recovery. The samples were analysed for EPO, and concentrations of serum iron (Fe), haptoglobin (Hapto), transferrin (Trans), ferritin (F er), haemoglobin (Hb) and packed cell volume (PCV). The nib had decrea sed by 6.77 kg at T3 (P < 0.01) and 0.68 kg at T5. The EPO and Hapto d ecreased during the survival training (P < 0.01) and increased during the recovery period (P < 0.01). The Fe increased during the survival t raining (P < 0.01) and remained above the control concentrations durin g recovery (P < 0.01). The Hapto decreased during the survival trainin g(P < 0.01) and remained below control concentration at T4 and T5 (P < 0.01). The Trans decreased continuously over the week (P < 0.01). The Fer in creased during the survival training (P < 0.01) and returned t o control concentration at T5. The Hb increased from TI to T2 (P < 0.0 1) and had decreased significantly at T5 (P < 0.01). The PCV increased from T1 to T2 (P < 0.01) and remained below control levels afterwards (P < 0.01). From our study it was concluded that, in humans, prolonge d physical stress with food and fluid deprivation induces a marked EPO decrease, which is followed by a rapid increase during recovery to re store the reduced O-2 transport capacity.