ORIGINAL ARTICLE

IGFBP-3, a sensitive marker of physical training and overtraining

M Elloumi¹, N El Elj², M Zaouali², F Maso¹, E Filaire¹, Z Tabka², G Lac¹

¹ Laboratoire de Physiologie de la Performance Motrice, Université Blaise Pascal, Bat Biologie B, Les Cézeaux, 63177 Aubière Cedex, France
² Laboratoire de Physiologie et des Explorations Fonctionnelles, Faculté de Médecine Ibn Eljazzar, 4000 Sousse, Tunisia

Correspondence to:
Correspondence to:
Gérard Lac
Laboratoire de Physiologie de la Performance Motrice, Université Blaise Pascal, Bat Biologie B, Les Cézeaux, 63177 Aubière Cedex, France; Gerard.LAC{at}univ-bpclermont.fr

Objective: To investigate the response of the somatotrope axis (insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3)) to intense exercise in relation to tiredness.

Methods: The study involved 11 rugby players who completed a questionnaire intended to evaluate fitness or, conversely, overtraining and who agreed to plasma samples being taken before and after an international rugby match.

Results: The main finding of our study is that we observed strong negative correlations between IGF-1 (r = 0.652) and IGFBP-3 (r = 0.824) levels and the overtraining state estimated using the French Society of Sport Medicine questionnaire. In particular, there was a fall (of up to 25%) in IGFBP-3 levels after the match in the more fatigued subjects compared to an increase (of up to 40%) in fit subjects.

Conclusions: A fall in IGFBP-3 in response to an intense bout of exercise may represent an index of tiredness in highly trained sportsmen, as indicated by the scores obtained from the overtraining questionnaire.

Abbreviations: AFC, after the competition; BMI, body mass index; CV, coefficient of variability; G1, group 1; G2, group 2; GH, growth hormone; IGF-1, insulin-like growth factor-1; IGFBP-3, insulin-like growth factor binding protein-3; SD, standard deviation; SFMS, French Society of Sport Medicine

Keywords: IGF-1; IGFBP-3; overtraining; overtraining questionnaire; rugby match

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