Cardiorespiratory fitness

Demography

Type 2 diabetes

Endocrinology

Metabolic equivalent

Physics

Astronomy

Evening

Physical fitness

Physical therapy

Internal medicine

Sociology

Medicine

Physical activity

Morning

Diabetes mellitus

Diabetes Care

Moderate- to vigorous-intensity physical activity (MVPA) improves cardiovascular health. Few studies have examined MVPA timing. We examined the associations of timing of bout-related MVPA with cardiorespiratory fitness and cardiovascular risk in adults with type 2 diabetes.Baseline 7-day hip-worn accelerometry data from Look AHEAD participants (n = 2,153, 57% women) were analyzed to identify bout-related MVPA (≥3 METs/min for ≥10 min). Cardiorespiratory fitness was assessed by maximal graded exercise test. Participants were categorized into six groups on the basis of the time of day with the majority of bout-related MVPA (METs × min): ≥50% of bout-related MVPA during the same time window (morning, midday, afternoon, or evening), <50% of bout-related MVPA in any time category (mixed; the reference group), and ≤1 day with bout-related MVPA per week (inactive).Cardiorespiratory fitness was highly associated with timing of bout-related MVPA (P = 0.0005), independent of weekly bout-related MVPA volume and intensity. Importantly, this association varied by sex (P = 0.02). In men, the midday group had the lowest fitness (β = -0.46 [95% CI -0.87, -0.06]), while the mixed group in women was the least fit. Framingham risk score (FRS) was associated with timing of bout-related MVPA (P = 0.02), which also differed by sex (P = 0.0007). The male morning group had the highest 4-year FRS (2.18% [0.70, 3.65]), but no association was observed in women.Timing of bout-related MVPA is associated with cardiorespiratory fitness and cardiovascular risk in men with type 2 diabetes, independent of bout-related MVPA volume and intensity. Prospective studies are needed to determine the impacts of MVPA timing on cardiovascular health.

Association of Objectively Measured Timing of Physical Activity Bouts With Cardiovascular Health in Type 2 Diabetes