Results published in Journal of Exercise Nutrition and Biochemistry indicated that 12 weeks of vitamin D supplements at a daily dose of 1,200 IU in combination with circuit training produced greater improvements in body composition, abdominal fat, blood lipid, and insulin resistance index than vitamin D or circuit training alone.
“From the results of this study, it was concluded that vitamin D intake and circuit training for 12 weeks would have a positive effect on the abdominal fat and blood lipid of elderly women with vitamin D deficiency and type 2-diabetes,” wrote researchers from Kyung Hee University in Korea.
However, the Korean researchers still have unanswered questions, particular regarding the mechanism of action.
“According to weight and BMI results obtained in this study, the most significant reduction was in the group with vitamin D intake combined with circuit training,” theywrote. “However, it is difficult to determine whether a synergistic effect of vitamin D intake and circuit training for body composition was apparent.
“The mechanism through which the increase in the concentration of vitamin D in the body affects body composition is also difficult to explain, but it is interpreted that the vitamin D receptor (VDR) is activated by the action of 25(OH), and has a positive effect on body composition while improving the homeostasis control ability of calcium.”
Fifty-two elderly women with type-2 diabetes and vitamin D deficiency were recruited to participate in the study. The women were randomly assigned to one of four groups: The control group (no supplements and no exercise); the circuit training group; the vitamin D supplementation group; or the group receiving a combination of vitamin D supplementation and circuit training.
Results showed that the vitamin D only and control groups did not display any significant changes in body weight, fat mass, percent body fat, or BMI, but did decrease in the training groups.
The training groups also displayed improvements in total cholesterol, triglyceride, and LDL and HDL cholesterol levels.
All of the improvements were greater when training was combined with vitamin D supplementation.
“The abdominal fat results indicate that the increase of fat metabolism and the reduction of abdominal fat are effectively accomplished when combining exercise that increases direct physical activity with vitamin D intake rather than only independent treatment of vitamin D intake,” they wrote.
“It was concluded that the 12 weeks of vitamin D supplementation and circuit training would have positive effects on abdominal fat and blood lipid profiles in T2D and vitamin D deficient elderly women. Vitamin D supplementation was especially effective when it was complemented with exercise training.”
The study was funded by a grant from the National Research Foundation of Korea from the Korean Government.
Source: Journal of Exercise Nutrition and Biochemistry
Volume 18, Number 3, Pages 249-257, doi: 10.5717/jenb.2014.18.3.249
“Effects of vitamin D supplementation and circuit training on indices of obesity and insulin resistance in T2D and vitamin D deficient elderly women”
Authors: H.-J. Kim, C.-K. Kang, H. Park, M.-G. Lee