Participants
A total of 14 participants were recruited and consented to participate in the study. Two running participants (1 male, 1 female) completed the first test, but withdrew from the study before completing the second test due to schedule conflicts. A third participant (female cyclist) was forced to stop prior to completing the second test due to gastrointestinal distress upon ingestion of the first capsule, which was determined to be sodium after un-blinding the data. Data were analyzed for the 11 remaining participants (4 males, 7 females). Two participants chose to cycle for the 2-hr exercise tests, while 9 participants opted to run on the treadmill. All 11 participants had a background in endurance training; participants’ endurance training level varied from half-marathon training to full Ironman triathlon training and ultra-distance running. The majority of tests were separated by 1-2 weeks (13.5 ± 6.45 days). Three participants completed the tests more than two weeks apart (21, 22, and 26 days between tests). Characteristics of the participants are shown in Table 1.