Table 4.

Biochemical markers altered in overtraining syndrome

Altered markers	Level of alteration (overt, relative or exacerbated)*
Insulin tolerance test (ITT)
Cortisol during hypoglycaemia in response to ITT (μg/dL) Cortisol 30′ after hypoglycaemia in response to ITT (μg/dL) Cortisol increase during ITT (μg/dL)	Relative
ACTH 30′ after hypoglycaemia in response to ITT (pg/mL) ACTH change during ITT (pg/mL)	Overt
Growth hormone (GH) during hypoglycaemia in response to ITT (μg/L) GH 30′ after hypoglycaemia in response to ITT (μg/L)	Relative
Prolactin during hypoglycaemia in response to ITT (ng/mL) Prolactin 30′ after hypoglycaemia in response to ITT (ng/mL) Change in prolactin during ITT (ng/mL)	Relative
Basal hormones
Basal GH (μg/L)	Relative
Basal prolactin (μg/mL)	Relative
Oestradiol (pg/mL)	Overt
Total testosterone (ng/dL)	Relative
Testosterone-to-oestradiol ratio	Overt
Other hormones
Total catecholamines (μg/12 hours)	Exacerbated
Nocturnal urinary norepinephrine (μg/12 hours)	Overt
30′ after awakening salivary cortisol (ng/dL)	Relative
Immunological and muscular markers
Creatine kinase (U/L)	Exacerbated
Lactate (nmol/L)	Relative
Lymphocytes (/mm3)	Relative
Neutrophils (/mm3)	Relative
Platelet to lymphocyte ratio	Relative

Relative: Unaltered when compared with general population, but altered when compared with healthy athletes.

Exacerbated: Changes normally observed in healthy athletes that are exacerbated in the presence of overtraining syndrome.

*Overt: Markedly and exclusively altered in overtraining syndrome, when compared with both the healthy athletes and the healthy non-physically active subjects.

ACTH, adrenocorticotropic hormone.