PROLACTIN RESPONSE TO UNUSUAL PHYSICAL STRESS IN YOUNG FEMALE ATHLETES

A. Kochaсska-Dziurowicz, W. Gaweі, T. Gabrys

Institute of Occupational Medicine and Environmental Health, Sosnowiec,
Department of Obstetrics and Gynaecology, County Hospital in Їory,
Academy of Physical Education, Katowice,
Poland

Introduction.The hormonal response to stress is directly related to the intensity of of the stimulus and greatly depends on the individual`s perception of potentially stressful situation. In order to evaluate prolactin responses to unusual physical stress in women, we selected a group of female runners who were subjected to hard physical exertion. As they have never trained in such conditions - exercise to a complete exhaustion - we assume that preparations for such an exercise and exercise itself produced good model of a stress situation.

Material and methods. A group of 14 sportswomen aged 15-19 years (mean 16,4 ± 1,2 years) who trained running for 100-400 m distances was selected for the test. They never took any medication containing steroid hormones and were in good health at the time of test. They were menstruating, although in 4 cases cycles were irregular. They were in different stages of cycle at the time of test. Physical, training and gynaecological characteristisc were similar in the group.

The exercise was performed using bicycle ergometer (MONARU-824). Participants had to keep a steady speed of pedalling - 60 rotations/minute. Primary load was 1 W kg^-1 and increased stepwise every 3 minutes by 1 W kg^-1 until subject`s refusal due to exhaustion. Blood samples were collected from an indwelling venous catheter before exercise, at the moment of the end of test and 30 and 90 minutes later.

Prolactin levels were determined in serum using specific radioimmunoassay kits (Orion Spectria Diagnostica, Finland) applying tubes coated with antibodies. Results were analysed statistically with STATGRAPHICS program (Manngistics Rockville, MT, USA). Mean (x) and standard deviation (SD) were calculated after testing for normal distribution by chi-square distribution (x²) test. Differences between normal distribution groups were tested with t-Student's test.

Results. Mean level of prolactin before test was 238 ± 104,9 mU/l (range 94-452 mU/l). Just after the end of test average prolactin level was 259,2 ± 100,3 mU/l (range 94-418 mU/l). 30 minutes after completion of test average prolactin level fell to 204,1 ± 92,6 mU/l (range 64-379 mU/l). 90 minutes after the end of test average prolactin level was 204,1 + 92,6 mU/l (range 40-344 mU/l). Statistically significant difference from pre-stress values was noted 90 minutes after completion of the test (p<0,004).

Average number of load steps was 4,83 ± 0,8 (range 4-6), average exercise duration was 13 min 55 sec ± 3 min 10 sec (range 12-16 min). Calculated average power consumption during test was 271,47 ± 49 W (range 192-335 W).

Discussion. No significant changes were found in endocrinological profile of strenuously exercising oligomenorrheic adolescents (Creatsas 1992). Females recruited to this experiment showzed normal resting average levels of prolactin. Unlike in other experiments we observed only an insignificant rise in serum prolactin concentration immediately after test (Keiser 1987, Hale 1983). This rise can be attributed to adrenal activation associated with exercise (de Souza 1991, Voigt 1987). It was also observed that prolactin concentration increases linearly with exercise in highly trained eumenorrheic women irrespectively of the phase of menstrual cycle(Keizer 1987). This was not confirmed in our experiment.

Existing data indicate that prolactin response to purely psychological stress are rarely seen (Delitala 1987).

We conclude that in highly trained female athletes unusual physical exertion produces significant changes in prolactin levels only after stressor withdrawal.

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Kochacska-Dziurowicz, A. Prolactin response to unusual physical stress in young female athletes / Kochacska-Dziurowicz A., Gawei W., Gabrys T. // Человек в мире спорта : Новые идеи, технологии, перспективы : Тез. докл. Междунар. конгр. - М., 1998. - Т. 1. - С. 174-175.