Recently, nonexercise activity thermogenesis (NEAT) has been highlighted for its ability to prevent weight gain and obesity. It has also been shown that the long-range negative autocorrelation of glucose dynamics, considered to reflect long-term blood glucose controllability, breaks down in patients with diabetes.
The purpose of this study was to clarify the effect of restricted NEAT on the glycemic profile and/or control characterized by glucose autocorrelation.
The glucose dynamics of 10 young healthy subjects were measured by continuous glucose monitoring during a day with normal activity and a day with restricted NEAT. To estimate the correlation property of the glycemic fluctuation, we used detrended fluctuation analysis, a method that analyzes the long-range temporal autocorrelation of signals.
In the long-range regime (>130 min) on a normal activity day, the detrended fluctuation analysis scaling exponent was α 2 = 1.37 ± 0.21. This was significantly (P = 0.036) smaller than the reference “uncorrelated value” of α = 1.5, suggesting that glycemic fluctuation was negatively autocorrelated. In contrast, on a day with restricted NEAT in the long-range regime (>167.5 min), the exponent was α 2 = 1.57 ± 0.15; this was significantly (P = 0.024) larger than 1.5, implying a lack of negative correlation.
The negative autocorrelation of glucose dynamics disappears with restricted NEAT compared with normal activity. This indicates that NEAT, reflective of all nonvolitional muscle activity, plays an important role in long-range negative correlation and hence long-term blood glucose control in healthy young adults.
1Graduate School of Comprehensive Human Science, University of Tsukuba, Ibaraki, JAPAN; 2Division of Endocrinology and Metabolism, Department of Medicine, Jichi Medical University, Tochigi, JAPAN; 3Faculty of Health and Sports Science, Doshisha University, Kyoto, JAPAN; 4College of Engineering General Education, Nihon University, Fukushima, JAPAN; and 5Educational Physiology Laboratory, Graduate School of Education, The University of Tokyo, Tokyo, JAPAN
Address for correspondence: Yoshiharu Yamamoto, Ph.D., Graduate School of Education The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; E-mail: firstname.lastname@example.org.
Submitted for publication January 2012.
Accepted for publication July 2012.