Methods and Subjects
A population representing non-elite runners were targeted for recruitment in this study. All subjects were recruited as volunteers in 3 major cities of India (Mumbai, Pune and Bengaluru) between May to June 2012. All subjects who had taken part in the Mumbai Marathon held each year during the month of January were contacted through information from a common database and invited to volunteer for this study. A brief overview of the study including the aim of the study, inclusion criteria and study methodology was also mailed to obtain informed consent from each volunteer. The inclusion criterion was that the participant must be an endurance runner in regular practice and who could run for 1 hour. A total of 146 runners participated in the study with 7 females and 139 males with a mean age of 40±9 years (range, 20-65 years).
The study was conducted at designated sites around each city. The average temperature and average humidity at the time of the run was recorded at each test site. Each participant was asked to bring 3 completed forms on the morning of the study day. These included the runner’s profile (age, gender, height, weight, and contact information), running history (longest running distance, running hours per week, running mileage per week and best performance) and an informed consent. The participants were instructed to hydrate themselves well the day before as they would for any endurance race and to strictly avoid alcoholic beverages the previous night. On arriving at the study location, each participant was asked to empty his or her bladder after which their weight was measured on a conventional scale whilst subjects stood in their undergarments wearing a towel. The participants were then asked to run for an hour with strict instructions not to drink any fluid during the run. At the end of an hour of running, the participants then were asked to empty their bladder again, dry themselves of any sweat and then to weigh themselves again on a measuring scale in their undergarments wearing a towel. The sweat rate (in litres) was calculated as the difference between the body weight at the beginning and the end of the one-hour run. This technique of calculating sweat rate is an approximation.