Walking is practised by three times as many individuals (44.5%) as the next-most-popular activity swimming (15%) and about thirty-eight million adults claim to walk >3.2 km (2 miles) for pleasure at least once monthly⁽¹⁾. Walking appeals to both genders, young and old, is often very prolonged and can take place in severe weather. There are many health benefits claimed for regular walking but also risks, e.g. falls, hypothermia, dehydration⁽Reference Yorimoto, Nishikawa and Sakate²⁾, especially in the young and elderly. Strenuous walks, especially in hot weather, may compromise water and electrolyte balance, but this outcome may depend on knowledge of risks and requirements and experience. Most studies are of young fit individuals under extreme conditions. The present pilot study aimed to determine whether a recreational walk posed a challenge to the water and electrolyte balance of older walkers.

The five male and eight female subjects (mean age 56 (sd 7.54) years) were a self-declared healthy and fit convenience sample of adults known to the authors. The walk was flat, along the river Mersey promenade, and three groups undertook the walk on different days at their own pace with self-determined stops. Intake was not controlled. All measurements were made in a laboratory before and after the walk.

BP, blood pressure; PCV, packed cell volume.

This group of fit experienced walkers lost a significant amount of weight despite intake of fluid (and food). The estimates of change in body composition based on bioimpedance seem to be unreliable. PCV fell and Hb concentration was unchanged but changes in urine indicated that hypohydration occurred. Reaction time was unaffected. Hypohydration is a likely consequence of even modest recreational walks in experienced walkers in non-extreme weather.