Serum testosterone (T) were investigated at rest and following exercise during 6 weeks
of continuous and intermittent swimming training in male rats, and the regulatory
mechanisms of the changes were discussed by evaluating serum luteinizing hormone (LH),
and conducting GnRH (gonadotropin releasing hormone, 1.5μg/kg body weight) or hCG
(human chorionic gonadotropin, 25IU/kg body weight) challenge tests. Relative to the
resting level, serum T increased after intermittent exercise (6.47±1.58 vs 3.08±2.85
nmol/l), which was followed with the same changes in LH (12.81±4.21 vs 5.70±1.56 nmol/l).
Serum T was lower after continuous exercise compared to the resting level (2.02±0.53
vs 10.96±3.11 nmol/l), while LH level was higher than that in sedentary group (11.23±5.61
vs 5.00±1.61 nmol/l). No significant changes were observed in resting T during and
after intermittent training. A lower resting T level was shown at the end of 3 weeks
of continuous training as compared to the sedentary group (1.88±0.69 vs 12.36±2.10
nmol/l), but it increased after 6 weeks of training. Serum T increased significantly
in the intermittent training group after hCG treatment as compared to the saline treatment
(52.42±12.10 vs 6.81±6.22 nmol/l), but insignificantly in the continuous training
group. The similar increases in serum LH were observed in all the groups after GnRH
treatment.
Key words:
Continuous exercise - intermittent exercise - testosterone - luteinizing hormone -
GnRH challenge test - hCG challenge test
