Researchers found that older adults' aerobic fitness levels are directly related to the incidence of age-related language failures such as 'tip-of-the-tongue' states.
The research, published in Scientific Reports, is the first of its kind to investigate the relationship between aerobic fitness levels and temporary cognitive lapses.
This includes not having a word come to mind when speaking - known as a 'tip-of-the-tongue' state.
People in a tip-of-the-tongue state believe they know a word but are unable to produce it, a phenomena which occurs more frequently as we grow older.
Researchers from the University of Birmingham, the University of Agder in Norway, the University of Leuven in Belgium and King's College London measured the occurrence of tip-of-the-tongue states in a psycholinguistic experiment.
The study compared a group of 28 healthy older adults with 27 young people in a 'tip-of-the-tongue' language test.
The first group had 20 women and eight men, with average ages of 70 and 67 respectively, while the younger one had 19 women and eight men with average ages of 23 and 22 respectively.
The test involved a 'definition filling task' on a computer.
Participants were asked to name famous people in the UK, including authors, politicians and actors, based on 20 questions about them.
They were also given the definitions of 20 'low frequency' and 20 'easy' words and asked whether they knew the word relating to the definition.
The groups underwent a static bike cycling test, a gold standard test which quantified their ability to use oxygen during exercise and their resulting individual aerobic fitness levels.
Dr Katrien Segaert, of the University of Birmingham's School of Psychology who led the study, said: "Older adults free from medical diseases still experience age-related cognitive decline.
"Significantly, what we found was that the degree of decline is related to one's aerobic fitness.
"In our study, the higher the older adults' aerobic fitness level, the lower the probability of experiencing a tip-of-the-tongue state."