Key takeaways
A 2019 review of over 2.5 million adults found fitness has declined since the 1980s
Children's shuttle-run fitness fell in most high-income countries from 1981, with the decline slowing after 2000
Rising body fat and less daily activity explain much of the fall
We are told that people are less active than they used to be. But are they actually less fit? Researchers led by Grant Tomkinson have spent two decades pulling together fitness test results from millions of children and adults to answer that question. The short answer: yes, in most places, aerobic fitness has fallen.
Children: the shuttle-run record
Many countries have tested schoolchildren with the 20 m shuttle run (the "beep test") for decades, which makes it a rare long-term record of population fitness.
- An early analysis by Tomkinson and colleagues (2003) of shuttle-run data from 11 countries found that children's aerobic performance had declined between 1980 and 2000.
- A later review (Tomkinson, Lang and Tremblay, 2019) covered children and adolescents in 19 high- and upper middle-income countries from 1981 to 2014. Fitness declined in most countries, in boys and girls, with the fastest fall in the 1980s and 1990s and a slowdown or plateau after about 2000.
The pattern was not uniform: some countries declined much more than others, and a few showed little change.
Adults: 2.5 million people over five decades
Lamoureux and colleagues (2019) pooled data on more than 2.5 million adults from 1967 to 2016. Adult fitness was broadly stable or rising until the 1980s and has declined since, in men and women and across age groups. The decline was seen in high-income countries, where most of the data come from; evidence from elsewhere is thin.
| Group | Trend in cardiorespiratory fitness | Main source |
|---|---|---|
| Children and adolescents | Declined from 1981, slower after 2000 | Tomkinson et al., 2019 |
| Adults | Declined from the 1980s | Lamoureux et al., 2019 |
| Physical activity, worldwide | High levels of insufficient activity, little improvement 2001–2016 | Guthold et al., 2018 |
Why is fitness falling?
- More body fat. Most field tests and VO2max values are expressed per kilogram, so a heavier population scores lower even if hearts and lungs are unchanged. Rising obesity explains a good part of the decline. See VO2max and body weight.
- Less daily movement. Cars, desk jobs and screens have reduced everyday activity. A WHO-led analysis by Guthold and colleagues (2018) estimated that around a quarter of adults worldwide do not meet activity guidelines, with little improvement over 15 years.
- Social factors. Income inequality, urban design and less active travel to school have been suggested, though these are harder to measure.
These explanations come from trends and associations, so cause and effect cannot be proven for any one factor.
Why it matters
Fitness is one of the strongest predictors of health and survival (see VO2max and longevity). A population-wide fall in fitness, especially in children, is likely to show up later as more heart disease, diabetes and disability, and a smaller margin before everyday tasks feel hard in old age (see VO2max and ageing).
There is also a practical consequence for norms: average values today may be lower than older reference tables. Being "average" for your age is not the same as being fit. Compare yourself against the norms by age and sex and the VO2max chart, and aim for above average.
The good news: individual fitness is trainable
Population trends do not decide your own number. VO2max responds to training at any age, often by several ml/kg/min within months (see VO2max trainability). Team sports like football and simple habits such as running or cycling to work all count.
- Estimate your baseline with the VO2max calculator.
- Follow a simple plan from how to improve VO2max.
- For more on the evidence, browse the research overview.
Frequently asked questions
Are people less fit than they used to be?
On average, yes. Large reviews show that the aerobic fitness of both adults and children in many countries has declined since around the 1980s.
Why is fitness declining?
The main suspects are rising body fat and less physical activity in daily life, from transport to work. Fitness tests measured per kilogram are especially affected by weight gain.
Does a population decline affect my own VO2max?
No. Your fitness depends on your own training, weight and age. It does mean that average norms today may be lower than older reference values.
Sources
- Lamoureux NR, et al. Temporal trends in the cardiorespiratory fitness of 2,525,827 adults between 1967 and 2016: a systematic review. Sports Med, 2019.
- Tomkinson GR, Lang JJ, Tremblay MS. Temporal trends in the cardiorespiratory fitness of children and adolescents representing 19 high-income and upper middle-income countries between 1981 and 2014. Br J Sports Med, 2019.
- Tomkinson GR, et al. Secular trends in the performance of children and adolescents (1980–2000): an analysis of 55 studies of the 20m shuttle run test in 11 countries. Sports Med, 2003.
- Guthold R, et al. Worldwide trends in insufficient physical activity from 2001 to 2016: a pooled analysis of 358 population-based surveys with 1.9 million participants. Lancet Glob Health, 2018.