The Health Journey Study

The main scientific aim of the Health Journey Study was to examine associations between lifestyle behaviors and health-related risk factors within a single cohort across three life stages: adolescence, emerging adulthood, and established adulthood. The emphasis is on examining changes in health from adolescence to adulthood and on investigating how early-life health is linked to adult health.
An Icelandic cohort born in 1988 was measured at ages 15 (Wave 1 in 2003, N = 443), 23 (Wave 2 in 2011, N = 201), and 36 (Wave 3 in 2024, N = 491). In 2003, Iceland was highly homogeneous. Therefore, the sampling strategy emphasized the geographical distribution of participants (rather than ethnicity or religion) to represent the population of both rural and urban regions. Objective measures included aerobic fitness, physical activity (PA), sedentary behavior, sleep, body composition, blood pressure, grip strength, and blood values. Subjective measures included self-reported mental and physical health, sleep, social functioning, PA, education, living arrangements, nutrition, and alcohol and nicotine use.