Hydration in female drivers in a 1044 km dog sled race in Finnmark

Drinking strategies during long dog sled competitions are important to avoid dehydration. Most of the studies involving dog sled racers (mushers) refer to male subjects. The purpose of this study was to study female mushers participating in a dog sled race of 1044 km, with a focus on hydration and drinking behavior.

Two female mushers (aged 50 and 23 years), of the 6 who signed up for participation in the dog sled 1044 km race, volunteered for the study. Before the race, maximum oxygen uptake and maximum heart rate (HR) were determined. Body compositions was measured before and shortly after the race. Heart rate was continuously measured by a HR monitor in the first 2 legs of the race, and urine samples were collected during the race. Urine osmolality and urine specific gravity were determined using freezing point depression and handheld refractometer. Values of urine osmolality greater than 900 mOsm · L(-1) and specific gravity greater than 1.030 were used as signs of dehydration.

The older musher had a mean HR of 65%, and the younger musher had a mean HR of 57% of the predicted maximum HR. The mushers reached a peak HR of 91% of their predicted maximum; they worked at an average HR of 55% (average of all legs). The younger woman had urine osmolality values above the dehydration limits in most of the samples. Only small changes in the before and after race anthropometric measurements were found.

Dog sled racing is a strenuous activity and drinking strategies are important to avoid dehydration. It seems that the drinking strategy of our subjects was adequate to supplement the hydration loss; yet, emotional arousals occurring during the race may affect drinking behavior. The attentive assistance of the mushers' handlers is therefore important.