Friday Morning Poster Presentations: Posters displayed from 7:30 a.m.-12:30 p.m.: One-hour author presentation times are staggered from 8:30-9:30 a.m. and 9:30-10:30 a.m.: E-24 Free Communication/Poster - Applied Exercise Immunology: FRIDAY, JUNE 2, 2006 8:30 AM - 10:30 AM ROOM: Hall B
PURPOSE: To examine the effect of nocturnal exercise at two different ambient temperatures on salivary cortisol and immunoglobulin A (s-IgA) in healthy young men.
METHODS: Five healthy collegiate men who had not smoked and had no mental or endocrine diseases (21.0±3.4yrs, 175.8±3.8 cm, 70.0±7.3 kg, 10.6±1.4% body fat) participated in two separate (at least 15 days), counter-balanced, experiments. In each experiment, subjects cycled on a stationary bike for 60 min at 55% of maximal heart rate (HR) beginning at 0100 in 15 lux for four consecutive days. In one experiment, subjects cycled at 26°C raising body temperature (HC) from 35.7±0.7 at resting to 36.2±0.6°C at 60 min of exercise. In another experiment, they exercised at 17°C suppressing body temperature with cooling devices (LC) from 33.4±1.1 at resting to 33.2±0.6°C at 60 min of exercise. During the experiment, they started to sleep at 0400, woke up at 1200, and were asked to maintain normal activity level during rest of the day. During exercise, rectal and skin temperatures, and HR were continuously monitored and recorded. In each experiment, approximately 2–3 ml of stimulated saliva was collected in Salivette for one min at 0100, 0200, 0400, and 1200 hours on day 1 and 4, and analyzed for salivary cortisol and s-IgA.
RESULTS: Salivary cortisol concentration on day 1 was 0.05±0.04, 0.12±0.09, 0.06±0.03, and 0.42±0.17 at HC, and 0.06±0.02, 0.09±0.05, 0.13±0.06, and0.47±0.11 ug/dLatLCat0100, 0200, 0400, and 1200, respectively, and the values at 1200 were higher than three previous time periods in both conditions (p < 0.05) without difference between conditions (p > 0.05). Cortisol on day 4 was 0.06±0.03, 0.08±0.06, 0.04±0.03, and 0.52±0.10 in HC, and 0.06±0.02, 0.10±0.06, 0.07±0.02, and 0.53±0.09 ug/dL at LC at each sampling time. No condition and time interactions were found in cortisol concentration on day 4. s-IgA on day 1 was 52.0±37.1 and 70.4±40.0 at HC, and 46.8±18.1 and 40.0±19.5 mg/dL at LC at 0100 and 0200, respectively. s-IgAonday 4 was 27.0±7.7 and 55.0±26.8 in HC, and 35.2±8.9 and 54.8±27.3 mg/dL at LC at 0100 and 0200, respectively. No condition and time interactions were found in s-IgA on day 4.
CONCLUSIONS: These data indicated that a nocturnal exercise with varying body temperature in different ambient temperatures did not influence salivary cortisol and s-IgA responses in healthy men.