Here is yet another reason for gym bunnies to feel smug: exercise may be the best way to stave off dementia.

Research published in the journal Neurology found that middle-aged women with high physical fitness were 88 percent less likely than those with moderate physical fitness to develop the neurodegenerative disease. Meanwhile, those that did developed it much later than their less active peers.

“These findings are exciting because it’s possible that improving people’s cardiovascular fitness in middle age could delay or even prevent them from developing dementia,” study author Helena Hörder, from the University of Gothenburg, Sweden, said in a statement.

This is one of the longest-spanning studies of its kind, launching in 1968 when researchers measured the peak cardiovascular capacity of 191 women with an average age of 50. The volunteers were asked to exercise on a bike machine until they were exhausted, at which point their peak level was noted.

Forty women achieved 120 watts or higher, putting them in the high-level fitness bracket. A further 92 had medium-level fitness (81 to 120 watts) and 59 exhibited low-level fitness (80 watts or less). Some of those in the low-level fitness category were unable to complete the exercise due to chest pain, high blood pressure, or cardiovascular issues.

The volunteers were tested for dementia six times over the next 44 years, within which 44 (or 23 percent) went on to develop the disease. Yet, interestingly, the odds of diagnosis varied widely depending on a volunteer’s fitness level. While close to half (45 percent) of all those who did not finish the test developed dementia, only 5 percent of the highly fit women were ever diagnosed with the condition. Thirty-two percent of those categorized as low fitness and 25 percent of those of medium fitness developed dementia during that time.

But that’s not all. The two highly fit women who did develop dementia did so at an average of 11 years later than those who were moderately fit.

“This indicates that negative cardiovascular processes may be happening in midlife that could increase the risk of dementia much later in life,” Hörder added.

However, there were limitations to the study, such as its small size and the fact that all volunteers were women from Sweden. As the researchers point out, the women's fitness levels were only measured once so it doesn't confirm if they maintained or improved their fitness levels post-1968. Again, this could affect the results.

However, it does seem to support older studies that link physical activity to a significantly reduced risk of developing dementia – even if it is not as much as 88 percent.