Int J Sports Med 2006; 27(2): 105-111
DOI: 10.1055/s-2005-837621
Physiology & Biochemistry

© Georg Thieme Verlag KG Stuttgart · New York

The Intensity Level of Physical Exercise and the Bone Metabolism Response

L. Maïmoun1 , 2 , J. Manetta3 , I. Couret4 , A. M. Dupuy5 , D. Mariano-Goulart4 , J. P. Micallef6 , E. Peruchon6 , M. Rossi4
  • 1Groupe de Recherche Interdisciplinaire Sur le Métabolisme Osseux (GRISMO), Montpellier, France
  • 2Centre Propara, Montpellier, France
  • 3Service Central de Physiologie Clinique, CHU Lapeyronie, Montpellier, France
  • 4Service de Médecine Nucléaire, CHU Lapeyronie, Montpellier, France
  • 5Service de Biochimie, CHU Lapeyronie, Montpellier, France
  • 6INSERM, Montpellier, France
Further Information

Publication History

Accepted after revision: January 30, 2005

Publication Date:
02 June 2005 (online)

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Abstract

This study investigated the short-term effects of the intensity level of physical exercise on bone metabolism and related hormones. The responses of calciotropic hormones and bone biochemical markers were evaluated in seven male cyclists (mean age 24.4 years, range 20 - 39) during two 50-min cycling tests performed 15 % below (-VT) and 15 % above (+VT) the ventilatory threshold. In each test, venous blood samples were drawn at rest, at the 30th and 50th min of exercise, and after 15 min of recovery. For both intensity levels, no significant variation in calcium, 25-hydroxyvitamin D, 1.25-dihydroxyvitamin D, or cortisol level was observed. Intact parathyroid hormone (iPTH) level increased significantly after the last minute of the test (41 %, p < 0.05) and peaked during the recovery (80 %, p < 0.05) only in response to exercise performed at +VT. Serum phosphorus concentration rose during both tests, while albumin levels increased only at +VT. Concerning bone cell activity, osteocalcin, and type I - C telopeptide breakdown products transiently increased only in response to exercise performed at +VT (11 % and 16.8 %, respectively; p < 0.05). Bone alkaline phosphatase increased similarly for both intensity levels after 30 min (12 %, p < 0.05) and 50 min (12 % for -VT vs. 14 % for +VT, p < 0.05). All markers of bone turnover returned to initial values during the recovery. In conclusion, a no-impact but intense and sustained exercise performed at +VT transiently stimulated bone turnover and iPTH secretion, suggesting the existence of a bone stimulation threshold. In addition to the well known effect of mechanical constraints, both the duration and intensity of exercise may induce changes in bone turnover.

References

Laurent Maïmoun

Centre Propara, Parc Euromedecine

263, rue du Caducée

34195 Montpellier

France

Phone: + 33467046704

Fax: + 33 4 67 54 35 36

Email: laurent.maimoun@oreka.com