Children today are 15% less fit than their parents and would take 90 seconds longer to run a mile Children's cardiovascular fitness is declining steadily across the world The falling fitness levels in children could lead to worse health in adulthood The main cause of falling fitness is increasing levels of obesity Many older people claim that â€˜things were better in my dayâ€™ and new research suggests that when it comes to childhood fitness, they might just be right. The study found children today are not as fit as their parents were. Today's children have a cardiovascular fitness 15 per cent lower than their parents did at the same age. Today's children have a cardiovascular fitness 15 per cent lower than their parents did at the same age They would also run a mile around 90 seconds slower than children 30 years ago could. Researchers found children's cardiovascular fitness is declining worldwide, and the decline in running fitness may indicate worse health in adulthood. The main reason is an increase in body fat. Lead author Dr Grant Tomkinson, senior lecturer at the University of South Australia's School of Health Sciences, said: â€˜If a young person is generally unfit now, then they are more likely to develop conditions like heart disease later in life. â€˜Young people can be fit in different ways. They can be strong like a weightlifter, or flexible like a gymnast, or skilful like a tennis player. â€˜But not all of these types of fitness relate well to health. â€˜The most important type of fitness for good health is cardiovascular fitness, which is the ability to exercise vigorously for a long time, like running multiple laps around an oval track.â€™ Researchers analysed 50 studies on running fitness between 1964 and 2010 that involved more than 25 million children in 28 countries. Today's children would take 90 seconds longer to run a mile than their parents did They gauged cardiovascular fitness by how far youngsters could run in a set time or how long it took to run a set distance. The researchers found cardiovascular endurance declined significantly during the 46 years. Average changes were similar between boys and girls, younger and older children, and across different regions, although they varied country to country. The study is the first to show that childrenâ€™s cardiovascular fitness has declined around the globe since about 1975. Across nations, endurance has declined consistently by about five per cent every decade. Dr Tomkinson said declines in cardiovascular endurance are probably caused by social, behavioural, physical, psycho-social and physiological factors. Country-by-country fitness findings are mirrored in measurements of obesity and body fat, suggesting they may be linked. Dr Tomkinson said: â€˜In fact, about 30 per cent to 60 per cent of the declines in endurance running performance can be explained by increases in fat mass.â€™ He said children should engage in at least 60 minutes of daily activities that use the body's big muscles, such as running, swimming or cycling. He added: â€˜We need to help to inspire children and youth to develop fitness habits that will keep them healthy now and into the future. â€˜They need to choose a range of physical activities they like or think they might like to try, and they need to get moving.â€™