Contribution of walking, running and cycling to moderate-to-vigorous and total physical activity in adolescents and adults across and within seasons: cross-sectional data from the Norwegian HUNT Study.

Objectives: To examine the contribution of walking, running and cycling to moderate-to-vigorous physical activity (MVPA) and total physical activity (TPA) across and within seasons in adolescents and adults. Methods: We included 4433 adolescents (mean age 15.4 years, range 13-17, 56.4% female) and 28 082 adults (mean age 53.1 years, range 18-103, 56.9% female) who participated in the population-based HUNT Study from 2017 to 2019. Participants wore two accelerometers (mean wear time 5.6 days (SD 1.1), range 1-7 days), one on the thigh and one on the lower back, to determine MVPA (defined as moderate/brisk walking (>4.0 km/hour), running and cycling) and TPA (MVPA plus slow walking (≤4.0 km/hour)). Results: Median MVPA (min/week) across seasons was 224 (36% of TPA) in adolescents and 152 (24% of TPA), 150 (22% of TPA), 100 (17% of TPA) and 34 (8% of TPA) in adults aged 18-49, 50-64, 65-74 and ≥75 years, respectively. Slow walking constituted 64% of TPA across seasons among adolescents, increasing to 92% among those aged ≥75 years.Within seasons, moderate/brisk walking constituted 77-82% of MVPA in adolescents and 72-99% in adults. Adolescents accumulated 104 min/week (IQR 58-175) less MVPA during winter than summer. The corresponding differences in adults aged 18-49 and 50-64 years were 59 (40-90) and 51 (33-77), min/week, respectively. Seasonal differences in MVPA were less pronounced in the age groups 65-74 and ≥75 years. Conclusion: Moderate/brisk walking is the main contributor to MVPA in adolescents and adults. The level of MVPA, its seasonal variation and its relative proportion of TPA decrease from adolescence throughout adulthood.