Red cell and core temperature in spelunking

Alpine spelunking is practiced in darkness, isolation, cold and high humidity. In this paper we study the acute haematological effects of prolonged strenuous activity in five spelunkers who spent about 20 hours in a 700-meter deep cave without resting much or sleeping. On four occasions, we measured their red cell counts, haemoglobin, mean corpuscular volume and percentage changes of plasma volume. We also measured their rectal temperature to estimate, in the limits of this parameter, thermoregulatory response. After the spelunkers descended 5 hours to the bottom of the cave, we detected, in all of them, a significant increase in red cell counts and haemoglobin and a drop in mean corpuscular volume and plasma volume. The day after recovery, we found a significant drop in all red cell parameters and a rise in plasma volumes. Rectal temperatures peaked at the exit. These findings suggest that alpine spelunking induces an initial haemoconcentration (bottom of the cave) followed by a haemodilution (the day after recovery). Sport anaemia was not detected. The rise of rectal temperature suggests that spelunking is a very strenuous sport with possible transpiration problems.