With poor fitness an established health risk, a University of Otago study has added to concerns about the next generation’s health and led researchers to say that measures to improve physical fitness among New Zealanders are urgently needed.

The University of Otago research is part of the Dunedin Multidisciplinary Health and Development Study that carried out an exercise cycle fitness test on all study members when the parents were 15-year-olds in 1986-87. This was followed up by testing and weighing 343 of the study members’ children between 2007 and 2015, when they were also aged 15.

The study, published in the New Zealand Medical Journal today, found that not only was the second generation taller, heavier and had higher body mass indexes than their parents at the same age, but they were also less fit, raising fears they may have a higher burden of non-communicable disease due to poor fitness.

“The findings support our hypothesis that physical fitness has declined over a generation,” said the study, which was led by Professor Bob Hancox.

The decline in fitness was particularly noticeable for girls, who weighed more and were less fit than their mothers had been at the same age. The decline in fitness among boys was smaller, but they were also less fit than their fathers had been at age 15, once body weight was taken into account.

One of the researchers, Dr Helena McAnally, said that girls’ fitness test scores were about 25 per cent lower than their mothers’ generation.

“It is well recognised that girls become less physically active earlier in adolescence, and this may be why their fitness levels were so much lower,” Dr McAnally says.

“We know fitness in adolescent tracks into adulthood and so these changes may have important long-term consequences for health and wellbeing.”

Hancox explained that while trends of increasing levels of overweight and obesity among young people are well recognised, there has been little research on changes in fitness.

“Our study is unusual in that we have measured fitness using the same technique in two generations of New Zealanders. The findings support many people’s perception that young people are less active and fit than their previous generations,” Professor Hancox says.

The study measured fitness using a cycle test. The cycle test measure used is less likely to be influenced by changes in body weight than running tests because it does not require you to carry your weight while exercising. Therefore, findings of reduced fitness in this research are not likely to be explained by increases in body weight.

“In summary, we have shown that the trend to increasing body weights among New Zealand adolescents has been accompanied by a decline in aerobic fitness,” says the researchers’ NZMJ article. “These trends are likely to result in an increased burden on health and society as a whole. Physical fitness in adolescence tracks into adulthood, and poor fitness is an established health risk. Measures to improve physical fitness among New Zealanders are urgently needed. “

The research was funded by the Health Research Council of New Zealand and supported by the Department of Preventive and Social Medicine. It was published today in the New Zealand Medical Journal.


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