The 25-year study, run by the Sports Institute at the Karlsruhe Institute of Technology (KIT), is called 'Gesundheit zum Mitmachen', which translates roughly to 'health through participating'.

It was initiated by sports scientists Klaus Bös und Alexander Woll and involved almost 500 volunteers from the Bad Schönborn in the state of Karlsruhe, the Stuttgarter Zeitung reports.

Since 1992 the participating men and women, aged between 35 and 80, were tested regularly on strength, flexibility, stamina and fine motor skills.

The unique long-term project has both scientific and practical purposes: the initiation and implementation of measures which promote health as well as the planning and conception of a long-term scientific study into the correlation between activity, fitness and health.

According to Klaus Bös, former head of the KIT Sports Institute, the question of nutrition was deliberately left out of the study as, “it would have gone beyond the scope of the framework and we simply lacked the sufficient expertise in that wide field.”

When the KIT study first began in 1992, 500 people aged 35 to 55 were chosen at random to be tested and were invited back for further testing every five years, alongside a new 'class' of 35-year-olds.

A little over 120 people took part in all the tests over the 25 year period, with a proportion of volunteers dropping out at various points along the way.

During each phase, subjects filled out questionnaires on their health and sporting habits. Their fitness was then assessed with physical tests observed by a doctor, a medical technical assistant and a sports scientist.

Blood samples, body fat measurements and psychological health of the volunteers were also studied.

Health problems inevitably increase with age but results from the KIT study confirm that people who regularly take part in active hobbies have far fewer complaints than those who are inactive.

Those who do not achieve 2.5 hours of moderate physical activity per week, as recommended by the World Health Organisation, are three times more likely to develop circulatory, cardiovascular, orthopaedic and neurological problems, as well as being four times more likely to suffer from type 2 diabetes, than those who are active. 

The KIT study also reports a significant increase in physical and sporting activities in the Bad Schönborn population.

The largest increase was visible for the age range of 51- to 60-year-olds as, while this age group took part in on average only 45 minutes of exercise per week in 1992, this had increased to 120 minutes by 2015.

According to Klaus Bös, it doesn't really matter what kind of sport you're doing.

“Sport has to fit with people, not vice versa,” which means it could be walking, jogging, bike riding, swimming or anything else that gets your heart-rate up.