Short Periods of Intense Physical Activity Associated With Cardiorespiratory Fitness—Especially in Men With Type 2 Diabetes

Bouts of intense exercise can lead to cardiorespiratory fitness and decreased risk for cardiovascular disease in patients with type 2 diabetes.

Bout-related moderate to intense physical activity was associated with improved cardiorespiratory fitness in patients with type 2 diabetes, but especially male patients, according to findings published in Diabetes Care.

Research over time has found that exercise at specific times of the day can lead to more weight loss, glucose control and cardiovascular responses. In this featured study, researchers describe how bouts of moderate to vigorous intensity physical activity may effect cardiovascular health in men with type 2 diabetes.

The goals of this study were three-fold. First, researchers, who were led by Jingyi Qian, PhD, of Brigham and Women’s Hospital, Boston, set out to characterize the temporal distribution (timing) of bout-related moderate to vigorously intense physical activity in overweight or obese adults with type 2 diabetes. Second, they sought to define whether the timing of physical activity varied according to sociodemographic or anthropometric factors at baseline. And, finally, they sought to determine associations of timing of bout-related physical activity with baseline cardiorespiratory fitness, which is an independent predictor for cardiovascular complications, overall mortality and risk for coronary heart disease.

The study is based on an analysis of data from the Look AHEAD (Action for Health in Diabetes) study, a landmark clinical trial of overweight or obesity adults with type 2 diabetes. The patients were randomized to either an intensive lifestyle intervention or diabetes support and education in order to assess the effects of the lifestyle intervention on cardiometabolic outcomes.

The new study included 2,035 overweight or obese adults with type 2 diabetes from Look AHEAD from 8 sites in the United States. Patients were assessed for physical activity by a hip-mounted RT3 triaxial accelerometer for 7 days. Cardiorespiratory fitness was defined as the level of metabolic equivalent tasks (METs) needed to intake 3.5 mL/kg/min of oxygen. Bout-related moderate to vigorous physical activity was defined as at least 3 metabolic equivalent tasks of at least 10 minutes.

Separated by bout-related physical activity groups, no group differences were observed for BMI, blood pressure, diabetes duration, fasting glucose, fasting glycated hemoglobin, lipid parameters, or smoking status. Inactive individuals or those more active in the evening had the highest and lowest Beck depression scores, respectively (P <.001). Individuals most active in the evening were the youngest (P <.001). Inactive individuals were most heavily biased toward female gender (P <.0001) and Black ethnicity (P =.03).

In general, cardiorespiratory fitness differed among the bout-related physical activity cohorts (P <.0001). Compared with individuals who exhibited a mixed physical activity pattern, those who were inactive had lower fitness (mean b, -0.46; 95% CI, -0.67 to -0.26 METs) and those who were active in the morning had greater fitness (mean b, 0.25; 95% CI, 0-0.5 METs).

Adjusting for bout-related metabolic equivalent tasks by minutes per week, inactive (mean b, 0.44; 95% CI, 0.21-0.68 METs), evening (mean b, 0.29; 95% CI, 0.04-0.54 METs), and morning (mean b, 0.25; 95% CI, 0.01-0.49 METs) cohorts had higher fitness than the mixed group.

Stratified by gender, men in the midday group had lower cardiorespiratory fitness (mean b, -0.46; 95% CI, -0.87 to -0.06 METs) and those in the morning group had higher fitness (mean b, 0.36; 95% CI, -0.03 to 0.75 METs) compared with the mixed group (P =.02). For the women, the inactive group also had a lower fitness level (mean b, -0.26; 95% CI, -0.5 to -0.02 METs) and those in the evening group, higher fitness (mean b, 0.35; 95% CI, 0.04-0.66 METs) compared with the mixed group (P =.0006).

Among men, the association between the Framingham risk score was increased among the morning group (mean b, 2.18; 95% CI, 0.7-3.65 METs; P <.01). No other significant associations were observed after correcting for gender, age, ethnicity, education, location, diabetes duration, smoking status, Beck depression score, average bout intensity, and bout-related METs ´ minutes per week.

This study was limited by its cross-sectional design. It remains unclear whether patterns of physical activity have a causative effect on fitness or cardiovascular risk.

These data indicated bout-related moderate to vigorous physical activity among overweight or obese men with T2D was associated with cardiorespiratory fitness. The men who were most active in the morning were at increased risk for coronary heart disease.

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.


Qian J, Walkup M P, Chen S-H, et al. Association of Objectively Measured Timing of Physical Activity Bouts With Cardiovascular Health in Type 2 Diabetes. Diabetes Care. 2021;44(4):1046-1054. doi:10.2337/dc20-2178.