Nighttime Workouts Better for Lowering Blood Glucose?

TOPLINE:

Daily life activity that happens mostly in the evening is associated with lower glucose levels in sedentary adults with overweight or obesity, particularly in those with impaired glucose regulation.

METHODOLOGY:

• Afternoon and evening exercise sessions improve glucose homeostasis in adults with overweight or obesity, but little is known about the timing of lifestyle activity that accumulates naturally as part of daily lives.
• Researchers examined how the timing of physical activity affects glycemic control in 186 adults in Spain (mean age, 46.8 years; 50% women) with overweight or obesity (mean body mass index, 32.9) and at least one metabolic impairment (blood pressure, lipid levels, and glycemic control) who reported being inactive.
• They monitored physical activity and glucose levels for 14 consecutive days using an accelerometer and a continuous glucose monitoring device, respectively.
• Based on the duration of each day’s moderate to vigorous physical activity, individuals were categorized as inactive (0 minutes), somewhat active (0-21.4 minutes), active (21.4-42.9 minutes), or very active (> 42.9 minutes).
• Based on the timing, physical activity was classified as morning, afternoon, or evening if > 50% of the activity occurred during those periods; otherwise, it was labelled as “mixed.”

TAKEAWAY:

• The 24-hour mean glucose levels were approximately 1.0 mg/dL and 1.5 mg/dL lower on the somewhat active and very active days, respectively, than on inactive days.
• Physical activity concentrated in the evening was associated with lower mean glucose levels than inactivity: 24-hour (−1.28 mg/dL; P = .004), daytime (−1.10 mg/dL; P = .020), and overnight (−2.14 mg/dL; P = .002).
• Compared with inactivity, physical activity in the afternoon hours was associated with lower 24-hour (−0.98 mg/dL, P = .019) and overnight (−1.72 mg/dL, P = .007) mean glucose levels but not lower daytime mean glucose levels.
• The association was more pronounced in participants with impaired glucose regulation but was similar in men and women.

IN PRACTICE:

“These findings highlight the promising area of MVPA [moderate to vigorous physical activity] timing as a novel approach to improve metabolic health in people at risk of developing cardiovascular diseases,” the authors wrote.

SOURCE:

The study was led by Antonio Clavero-Jimeno, Department of Physical Education and Sports, University of Granada, Granada, Spain, and published online in Obesity.

LIMITATIONS:

The observational nature of the study may prevent the establishment of causal relationships. The lack of data on dietary intake and stress levels may have impacted the results as these factors are known to influence glucose regulation. Moreover, the precise impact of technical errors in the continuous glucose monitoring device and day to day variability could not be determined. The effect size in mean glucose levels was relatively modest, but the participants had a sedentary lifestyle, and the effect may be larger at higher activity levels.

DISCLOSURES:

The study was funded by the European Regional Development Fund, Spanish Ministry of Science, Innovation and Universities; University of Granada; and other European organizations. The authors declared no conflicts of interest.