National and international temporal trends in mean CRF (per decade) from 965 264 children aged 9–17 years from 19 countries between 1981 and 2014
| Group | Absolute changes in mL/kg/min (95% CI) | Per cent changes (95% CI) | ||
| Pre-2000 | Post-2000 | Pre-2000 | Post-2000 | |
| Poland | −7.6 (−8.1 to 7.1) | −2.4 (−2.7 to 2.1) | −17.8 (−18.9 to 16.7) | −5.2 (−5.8 to 4.6) |
| Lithuania | −5.0 (−5.2 to 4.8) | −5.0 (−5.4 to –4.6) | −11.2 (−11.7 to 10.7) | −11.2 (−12.0 to 10.4) |
| South Africa | −4.8 (−5.8 to 3.8) | −1.5 (−2.2 to 0.8) | −10.9 (−13.2 to 8.6) | −3.6 (−5.2 to 2.0) |
| Portugal | −3.7 (−4.7 to 2.7) | −0.8 (−1.1 to 0.5) | −8.0 (−10.0 to 6.0) | −1.7 (−2.4 to 1.0) |
| Australia | −3.5 (−3.9 to 3.1) | −0.4 (−0.7 to 0.1) | −7.9 (−8.8 to 7.0) | −0.9 (−1.6 to 0.2) |
| Seychelles | −3.1 (−3.2 to 3.0) | −3.1 (−3.3 to 2.9) | −7.3 (−7.6 to 7.0) | −7.3 (−7.7 to 6.9) |
| France | −2.6 (−2.9 to 2.3) | −3.4 (−3.5 to 3.3) | −5.4 (−6.1 to 4.7) | −7.9 (−8.2 to 7.6) |
| Canada | −2.2 (−2.4 to 2.0) | 0.4 (0.2 to 0.6) | −4.8 (−5.2 to 4.4) | 0.9 (0.6 to 1.2) |
| Hungary | −1.7 (−1.9 to 1.5) | −1.7 (−1.9 to 1.5) | −4.4 (−5.0 to 3.8) | −4.1 (−4.7 to 3.5) |
| Greece | −1.2 (−1.4 to 1.0) | 0.1 (−0.1 to 0.3) | −3.0 (−3.5 to 2.5) | 0.1 (−0.3 to 0.5) |
| Belgium | −1.1 (−1.4 to 0.8) | 2.0 (1.5 to 2.5) | −2.5 (−3.1 to 1.9) | 4.2 (3.0 to 5.4) |
| Spain | −1.1 (−1.3 to 0.9) | −0.3 (−0.5 to 0.1) | −2.7 (−3.1 to 2.3) | −0.7 (−1.1 to 0.3) |
| Italy | −0.7 (−0.9 to 0.5) | −0.6 (−1.0 to 0.2) | −1.7 (−2.3 to 1.1) | −1.8 (−3.1 to 0.5) |
| The Netherlands | −0.7 (−0.9 to 0.5) | −0.5 (−0.8 to 0.2) | −1.7 (−2.2 to 1.2) | −1.1 (−1.9 to 0.3) |
| Estonia | −0.2 (−0.4 to 0.0) | −0.2 (−0.5 to 0.1) | −0.3 (−0.6 to 0.0) | −0.4 (−1.0 to 0.2) |
| UK | 0.2 (0.0 to 0.4) | −2.4 (−2.6 to 2.2) | 0.5 (0.0 to 1.0) | −5.2 (−5.6 to 4.8) |
| USA | 0.3 (−0.4 to 1.0) | −1.1 (−1.4 to 0.8) | 0.8 (−0.9 to 2.5) | −2.6 (−3.2 to 2.0) |
| Brazil | 0.7 (−0.3 to 1.7) | 1.3 (0.8 to 1.8) | 1.3 (−1.0 to 3.6) | 3.4 (2.1 to 4.7) |
| Japan | 1.9 (1.6 to 2.2) | 1.4 (1.3 to 1.5) | 3.8 (3.3 to 4.3) | 2.8 (2.7 to 2.9) |
| Boys | −1.9 (−2.0 to 1.8) | −0.6 (−0.7 to 0.5) | −4.2 (−4.5 to 3.9) | −1.4 (−1.7 to 1.1) |
| Girls | −1.2 (−1.3 to 1.1) | −0.3 (−0.4 to 0.2) | −3.0 (−3.3 to 2.7) | −0.6 (−0.9 to 0.3) |
| Children (aged 9–12 years) | −1.6 (−1.7 to 1.5) | −0.7 (−0.8 to 0.6) | −3.5 (−3.8 to 3.2) | −1.7 (−1.9 to 1.4) |
| Adolescents (aged 13–17 years) | −1.6 (−1.7 to 1.5) | −0.1 (−0.2 to 0.0) | −3.8 (−4.1 to 3.5) | −0.3 (−0.5 to –0.1) |
| All | −1.6 (−1.7 to 1.5) | −0.4 (−0.5 to –0.3) | −3.6 (−3.8 to 3.4) | −0.9 (−1.1 to –0.7) |
Note: positive changes in means indicate increases in mean CRF and negative values indicate declines.
CRF, cardiorespiratory fitness.