A study of 22 amateur kickboxers found that repeated blows to the head can lower IGF‑1 levels and cause growth‑hormone (GH) deficiency, a type of pituitary problem. About one‑quarter of the fighters showed GH deficiency, and the more they trained or the older they got, the lower their IGF‑1 levels were.

Traumatic brain injury, which is a frequent and a worldwide important public health problem, may result in pituitary dysfunction. Concussion, a common type of lesion after traumatic brain injury, is an injury associated with sports including boxing and kickboxing. Kickboxing is one of the most popular martial arts and approximately 1-million people around the world participate in kickboxing sport. Head is the most common site of injury in amateur and professional kickboxers. Pituitary consequences of chronic repetitive head trauma in kickboxing have not been investigated until now. Therefore, the present study was designed to investigate the pituitary function in both retired and active amateur kickboxers. Twenty-two amateur kickboxers who have boxed in national and international championships (16 men, 6 women) with a mean age of 27.3 +/- 7.1 years, and 22 age- and sex-matched healthy controls were included in the study. Basal hormone levels were obtained from the participants. To assess GH-IGF-I axis, GHRH + GHRP-6 test and glucagon stimulation tests were used. Hypothalamo-pituitary-adrenal axis was assessed by glucagon stimulation test. When mean basal hormone levels were compared between kickboxers and the controls, IGF-I level was significantly lower in kickboxers (P < 0.05). Five (22.7%) and two (9.1%) of the 22 kickboxers had GH deficiency had ACTH deficiency, respectively. There were significant negative correlations between IGF-I levels and age, duration of sports and number of bouts (P < 0.05). Present data clearly demonstrate for the first time that amateur kickboxing is a novel cause of hypopituitarism and kickboxers are at a risk for hypopituitarism especially isolated GH deficiency. Therefore, participants of the combative sports who were exposed to chronic repetitive head trauma need to be screened.