Acute And Chronic NGF Responses During A Training Season In Young Swimmers

Nerve Growth Factor (NGF) is crucial for the functional accuracy of the cholinergic neurons in the central nervous system and for the growth and phenotypic maintenance of neurons in the peripheral nervous system. PURPOSE: We investigated the acute and chronic effects of a swimming training season of young athletes on serum NGF, both at rest and after a maximal exercise bout. METHODS: Eleven well-trained male swimmers (14.08 ± 1.0 yrs) participated in the study. Measurements were carried out at the beginning of the training season (T1) as well as pre- and post- taper of each of the two competitive periods (i.e., T2, T3 for the first macrocycle, and T4, T5 for the second macrocycle, respectively). Blood samples were drawn at pre- and 1 hour post a maximal, 400 m swimming testing. Serum NGF levels were measured by ELISA. Adjustment for exercise-induced plasma volume changes was performed before data analysis. Two-way ANOVA with repeated measures was used for statistics. RESULTS: Rest NGF values were not significantly different throughout the experimental period, although there was a tendency for them to increase from T1 to T5 (56%: T1 15.56 ± 1.4 vs T5 24.23 ± 5.6; p > 0.05). No significant differences were found among the post 400 m testing timepoints or between pre-post testing (p > 0.05) (T1: 15.56 ± 1.4 vs 19.31 ± 5.0; p > 0.05, T2: 15.16 ± 1.9 vs 14.35 ± 1.7; p > 0.05, T3: 16.34 ± 1.3 vs 13.99 ± 1.8; p > 0.05, T4: 16.81 ± 1.7 vs 17.18 ± 2.3; p > 0.05, T5: 24.23 ± 5.6 vs 18.27 ± 2.8; p > 0.05). CONCLUSIONS: This data suggest that long-term swimming training may affect the resting concentrations of circulating NGF in young swimmers. More studies are needed to further examine the NGF responses at different timepoints during the recovery period after acute bout(s) of swimming exercise.