Abstract
Thyroid hormones are important regulators of energy metabolism and may influence energy
processes during physical exercise. There are controversial results concerning thyroid
hormone metabolism during strenuous exercise in adult athletes and only scant data
concerning the impact of strenuous exercise on thyroid hormone metabolism in children
and adolescents. Although some studies demonstrate a transient change in thyroid hormones
during intense physical performance, most studies agree that these changes are of
minor impact, practically reflecting the relative negative energy balance during strenuous
exercise. This state of hypometabolism during intense physical performance has also
been confirmed in highly trained female young athletes, who may be also characterized
by reproductive axis dysfunction, manifested either as luteal-phase deficiency or
amenorrhea, alongside the typical constellation of low T3 , insulin and leptin levels. More importantly, strenuous exercise during childhood
or adolescence is mostly accompanied by a delay of skeletal maturation, and height
and may have a long-lasting negative effect on growth and acquisition of maximum bone
mass. In conclusion, although thyroid hormones are only transiently or insignificantly
changed during strenuous exercise, adequate caloric intake should be guaranteed in
highly performing young athletes in order to counteract the relative negative energy
balance and prevent alterations in endocrine-metabolic profile. Moreover, when growth
and pubertal progression in very young athletes are significantly impaired, a reduction
in the intensity of the physical exercise should be advocated in order to guarantee
better final height and adequate acquisition of bone mass.
Key words
Thyroid hormones - Metabolism - Sport - Exercise - Childhood - Adolescence - Female
athlete - Hypometabolic state - Growth - Pubertal delay
References
Eating disorders. In: Drinkwater BA (ed) Women in sport. Oxford, England; Blackwell Scientific 2000:
364-376
ganten@hol.gr
