Sara Mejia (sarahicks@mail.weber.edu)

Aerobic exercise provides multiple health benefits, some of these benefits are modulated by increased body temperature, vasodilation, sweating, and others. Previous studies have shown that exercising results in plasma uric acid (UA) increased concentrations. In this study, we sought to investigate if a 30-minute session of sauna-induced heat therapy has similar effects as exercising aerobically for the same amount of time on plasma UA. We hypothesize that heat therapy and exercise will increase concentrations of plasma UA.
Plasma from fourteen participants (age 23 ± 2 y, ht 1.74 ± 0.08 m, wt 80.9 ± 19.7, BMI 26.5 ± 5.5 kg/㎡) was collected and tested. Each participant completed a randomized crossover, counterbalanced control study. This trial consisted of a 20-minute resting period lying supine that was followed by 30 minutes of either sauna heat therapy (SAU: ~132°F/~56°C), cycling exercise (EXER: ~40-50% HRR), or upright sitting that served as the control (CON: control). At the completion of the trial, participants completed a 60-minute recovery period lying supine. Plasma samples were taken both pre- and post-completion of each activity for research evaluation.
Cycling exercise was the only treatment to increase UA concentration, EXER (pre 3.52 ± 0.16 vs post 3.67 ± 0.15; P = 0.03), SAU (pre 3.70 ± 0.17 vs post 3.73 ± 0.15; P = 0.85), CON (pre 3.90 ± 0.18 vs post 3.74 ± 0.14; P = 0.11).
Cycling for 30 minutes (40-50% HRR) was enough to increase UA levels. This is in accordance with previous studies showing that exercise increases vasopressin which concentrates plasma UA; in addition exercise results in lactic acid build up that prevents plasma UA excretion.
Sauna heat therapy for 30 min at ~132°F/~56°C did not affect plasma UA levels. Longer exposure or/and intensity may be required to observe noticeable changes in this marker.