abstract
- Stress experienced by young athletes (ages 11 to 23 years) during competition was studied by comparing urinary epinephrine (E) and norepinephrine (NE) excretion at rest, during bicycle exercise (55% max) and during a hockey game. Athletes were divided into four groups: 11, 12, 16, and 23 years olds with four subjects in each group. Urinary production rates were similar between experimental conditions and age groups. Both resting E and NE levels were constant across all ages. Game E levels were significantly higher (P less than 0.05) than resting and bicycle levels in both the 16 and 23 year old groups. Epinephrine excretion during hockey was also significantly higher (P less than 0.05) in the 23 year old athletes than in the 11 and 12 year olds and in the 16 year olds compared to the 11 year olds. Game NE was significantly elevated (P less than 0.05) above resting levels in the 16 and 23 year olds. Submaximal NE excretion was not significantly different from resting levels in any of the age groups (P greater than 0.05). Physical stress as reflected by NE excretion was constant across all ages within each experimental condition. Generally, sympathetic stimulation and NE excretion appeared to be related to intensity of physical activity, being greater during hockey than during submaximal exercise. Significant adrenal medullary activation and E excretion was evident only during hockey and then, only in the older athletes.