Decline in cardiorespiratory fitness in the Swedish working force between 1995 and 2017

Abstract

Background: Long-term trend analyses of cardiorespiratory fitness (VO₂ max) in the general population are limited.

Objectives: To describe trends in VO₂ max from 1995 to 2017 in the Swedish working force and to study developments across categories of sex, age, education, and geographic regions.

Methods: A total of 354 277 participants (44% women, 18-74 years) who participated in a nationwide occupational health service screening between 1995 and 2017 were included. Changes in standardized mean values of absolute (L/min) and relative (mL/min/kg) VO₂ max, and the proportion with low (<32) relative VO₂ max are reported. VO₂ max was estimated using a submaximal cycle test.

Results: Absolute VO₂ max decreased by -6.7% (-0.19 L/min) in the total population. Relative VO₂ max decreased by -10.8% (-4.2 mL/min/kg) with approximately one-third explained by a simultaneous increase in body mass. Decreases in absolute fitness were more pronounced in men vs women (8.7% vs 5.3%), in younger vs older (6.5% vs 2.3%), in short (11.4%) vs long (4.5%) education, and in rural vs urban regions (6.5% vs 3.5%), all P < 0.001. The proportions with low VO₂ max increased from 27% to 46% (P < 0.001).

Conclusion: Between 1995 and 2017, there was a steady and pronounced decline in mean cardiorespiratory fitness in Swedish adults. Male gender, young age, short education, and living in a rural area were predictive of greater reductions. The proportion with low cardiorespiratory fitness almost doubled. Given the strong associations between cardiorespiratory fitness and multiple morbidities and mortality, preventing further decreases is a clear public health priority, especially for vulnerable groups.

Keywords: VO2max; aerobic capacity; maximal oxygen consumption; population; secular trend.