Women are thought to be biologically sensitive to effects of extreme physical activity when accompanied by weight loss–possible negative consequences cited include bone fractures and fertility difficulties. Scientists from the University of Edinburgh and the Royal Centre for Defence Medicine, United Kingdom, examined the effects of an extreme challenge in six women who skied over 1,000 miles in 61 days, while pulling sleds weighing about 176 pounds. All in an environment of very low temperatures and high winds. The investigators monitored several health markers before and after the expedition, including stress, reproductive and metabolic function and fat and muscle levels.
Findings indicated that muscle levels and hormone markers of stress, fertility and bone strength were preserved, despite enduring such extreme exercise and losing on average 22 pounds in body fat. Some tests even showed evidence of exercise-related benefits by two weeks after the expedition had ended. These findings contain some potentially myth-busting data on the impact of extreme physical activity on women.
These investigators have shown that, with appropriate training and preparation, many of the previously reported negative health effects of such challenges can be avoided. The low number of highly-selected women means the findings may not be applicable to all. More research is needed to compare these measures in women with men, and to explore whether factors like dietary content, adequate sleep or psychological preparation might have protected women against the negative effects of extreme exercise with weight loss.