Case studies in physiology: Impact of a long-distance hike on the Pacific Crest Trail on arterial function and body composition in a highly fit young male.

The Pacific Crest Trail (PCT) is a 4265-km hiking trail that extends from the US-Mexican border to the US-Canadian border through the mountain ranges of western North America. Individuals who hike the entire length of the trail in one season (4-6 months) perform long daily exercise durations while exposed to extreme environmental temperatures, high altitudes, intense solar radiation, and the consumption of calorie-rich, nutrient-poor diets. This case study reports changes in arterial function and body composition in a subject before and after a 112-day long-distance hike of the PCT. Brachial artery flow-mediated dilation, a measure of vascular endothelial function, decreased from: 6.97% to 5.00%. Carotid-femoral pulse wave velocity, a measure of aortic stiffness, increased from 5.39 to 5.76 m/s. Dual-energy x-ray absorptiometry scans detected no major changes in total-body bone mineral density, fat mass, or lean mass, although there were minor, unfavorable changes in some subregions of the body. It is important for individuals completing a long-distance hike to be aware of the potential deleterious changes associated with large volumes of exercise and consuming a high-calorie, low-quality diet.