The effect of acute exercise on undercarboxylated osteocalcin in obese men
The purpose of this study was to examine if the reduction in glucose post-exercise is mediated by undercarboxylated osteocalcin (unOC). Obese men were randomly assigned to do aerobic or power exercises. The change in unOC levels was correlated with the change in glucose levels post-exercise. The reduction in glucose post-acute exercise may be partly related to increased unOC.
Osteocalcin (OC) in its undercarboxylated (unOC) form may contribute to the regulation of glucose homeostasis. As exercise reduces serum glucose and improves insulin sensitivity in obese individuals and individuals with type 2 diabetes (T2DM), we hypothesised that this benefit was partly mediated by unOC.
Twenty-eight middle-aged (52.4 ± 1.2 years, mean ± SEM), obese (BMI = 32.1 ± 0.9 kg m−2) men were randomly assigned to do either 45 min of aerobic (cycling at 75% of VO2peak) or power (leg press at 75% of one repetition maximum plus jumping sequence) exercises. Blood samples were taken at baseline and up to 2 h post-exercise.
At baseline, unOC was negatively correlated with glucose levels (r = −0.53, p = 0.003) and glycosylated haemoglobin (HbA1c) (r = −0.37, p = 0.035). Both aerobic and power exercises reduced serum glucose (from 7.4 ± 1.2 to 5.1 ± 0.5 mmol L−1, p = 0.01 and 8.5 ± 1.2 to 6.0 ± 0.6 mmol L−1, p = 0.01, respectively). Aerobic exercise significantly increased OC, unOC and high-molecular-weight adiponectin, while power exercise had a limited effect on OC and unOC. Overall, those with higher baseline glucose and HbA1c had greater reductions in glucose levels after exercise (r = −0.46, p = 0.013 and r = −0.43, p = 0.019, respectively). In a sub-group of obese people with T2DM, the percentage change in unOC levels was correlated with the percentage change in glucose levels post-exercise (r = −0.51, p = 0.038).
This study reports that the reduction in serum glucose post-acute exercise (especially aerobic exercise) may be partly related to increased unOC.
KeywordsBone metabolism Exercise Glycaemic control Obesity Undercarboxylated osteocalcin
The authors wish to thank Dr. Thuy Vu for her assistance in recruitment and screening of volunteers. This study was partly funded by the Helen Macpherson Smith Trust and Victoria University Development Grant.
Conflicts of interest
- 10.Shiraki M, Yamazaki Y, Shiraki Y, Hosoi T, Tsugawa N, Okano T (2010) High level of serum undercarboxylated osteocalcin in patients with incident fractures during bisphosphonate treatment. J Bone Miner Metab (in press)Google Scholar
- 12.Fernandez-Real JM, Izquierdo M, Ortega F, Gorostiaga E, Gomez-Ambrosi J, Moreno-Navarrete JM, Fruhbeck G, Martinez C, Idoate F, Salvador J, Forga L, Ricart W, Ibanez J (2009) The relationship of serum osteocalcin concentration to insulin secretion, sensitivity, and disposal with hypocaloric diet and resistance training. J Clin Endocrinol Metab 94:237–245PubMedCrossRefGoogle Scholar
- 21.O’Leary VB, Jorett AE, Marchetti CM, Gonzalez F, Phillips SA, Ciaraldi TP, Kirwan JP (2007) Enhanced adiponectin multimer ratio and skeletal muscle adiponectin receptor expression following exercise training and diet in older insulin-resistant adults. Am J Physiol Endocrinol Metab 293:E421–E427PubMedCrossRefGoogle Scholar
- 22.Fatouros IG, Chatzinikolaou A, Tournis S, Nikolaidis MG, Jamurtas AZ, Douroudos II, Papassotiriou I, Thomakos PM, Taxildaris K, Mastorakos G, Mitrakou A (2009) Intensity of resistance exercise determines adipokine and resting energy expenditure responses in overweight elderly individuals. Diab Care 32:2161–2167CrossRefGoogle Scholar