Background The aim of this study was to investigate the effects of different exercise loads (short, medium and long swimming distances) on the thyroid hormone (THs) levels and serum lipid profiles of male professional swimmers. Materials and methods The participants in this study were 20 healthy male professional swimmers aged 18-22 years, who all competed at an elite level. The THs levels [thyroid-stimulating hormone (TSH), triiodothyronine (T3) and thyroxine (T4)] and serum lipid profile were also obtained. Results It was determined that the TSH and T4 values increased after exercise (p < 0.05). When compared to the pretest values, the increase in the TSH and T4 values following the L400 tests was statistically significant (p < 0.001 and p < 0.05). It was also determined that the changes in the cholesterol, high-density lipoprotein (HDL) and total glucose (TG) values were significant after exercise (p < 0.001). There was no significant difference between the groups in terms of the low-density lipoprotein (LDL) values (p = 0.07). According to the results, the cholesterol counts for the M200 and L400 groups were lower than the pretest counts (p < 0.001). When compared to the pretest values, the decrease in the HDL counts for the M200 and L400 groups was higher than the pretest HDL counts (p < 0.001 and p < 0.05, respectively). Further, the triglycerides counts for the M200 and L400 groups were higher than the pretest counts (p < 0.001). Conclusions Different exercise loads can have a positive impact on the physical health of swimmers via their lipid profiles and THs. Additionally, swimming exercise could be considered an efficient protective strategy against metabolic disorders, as it serves to balance the serum lipid levels.
Keywords: exercise; lipid metabolism; swimming; thyroid hormones.