Objective: To determine if drinking 2 mL/kg body mass of PJ, hypertonic saline, or deionized water (DIW) pre-exercise affects aerobic performance or thermoregulation.Design: Crossover study. Setting: Controlled laboratory study.Patients or Other Participants: Nine euhydrated men (age ¼ 22 6 3 years, height ¼ 184.0 6 8.2 cm, mass ¼ 82.6 6 16.0 kg) completed testing.Intervention(s): Participants rested for 65 minutes. During this period, they ingested 2 mL/kg of PJ, hypertonic saline, or DIW. Next, they drank 5 mL/kg of DIW. Blood was collected before and after ingestion of all fluids. Participants were weighed and ran in the heat (temperature ¼ 38.38C 6 18C, relative humidity ¼ 21.1% 6 4.7%) at increasing increments of maximal heart rate (50%, 60%, 70%, 80%, 90%, 95%) until exhaustion or until rectal temperature exceeded 39.58C. Participants were weighed postexercise so we could calculate sweat volume.Main Outcome Measure(s): Time to exhaustion, rectal temperature, changes in plasma volume, and sweat volume.Results: Time to exhaustion did not differ among drinks (PJ ¼ 77.4 6 5.9 minutes, hypertonic saline ¼ 77.4 6 4.0 minutes, DIW ¼ 75.7 6 3.2 minutes; F 2,16 ¼ 1.1, P ¼ .40). Core temperature of participants was similar among drinks (PJ ¼ 38.78C 6 0.38C, hypertonic saline ¼ 38.78C 6 0.48C, DIW ¼ 38.88C 6 0.48C; P ¼ .74) but increased from pre-exercise (36.78C 6 0.28C) to postexercise (38.78C 6 0.48C) (P , .05). No differences were observed for changes in plasma volume or sweat volume among drinks (P . .05).Conclusions: Ingesting small amounts of PJ or hypertonic saline with water did not affect performance or select thermoregulatory measures. Drinking larger volumes of PJ and water may be more effective at expanding the extracellular space.Key Words: acetic acid, core temperature, exhaustion, sodium, vinegar Key PointsIngesting 2 mL/kg body mass of pickle juice (PJ) or hypertonic saline with water pre-exercise did not affect performance. Ingesting PJ or hypertonic saline did not alter final core temperature or sweat volume. Ingesting PJ or hypertonic saline with modest volumes of water did not cause plasma volume expansion. Ingesting small volumes of PJ with water before exercise is unlikely to affect athletic performance or select thermoregulatory variables, such as rectal temperature or sweat loss.