New study reveals regular exercisers benefit from the same heart changes seen in athletes

INDIVIDUALS who work out for just a few hours a week could benefit from an enlarged heart, a phenomenon previously only recognised in athletes, according to a new UK study.

The research also provides important information for doctors who could be mistaking an enlarged heart resulting from exercise, known as "athlete's heart," for a heart condition.

For the study, one of the largest of its kind, a team of researchers based at Imperial College London recruited 1096 adults age 18-97 with a median age of 39, and asked participants to report on their physical activity levels over the past year.

Participants fell into one of four activity groups, level I, almost entirely sedentary; level II, light physical activity or exercise for one to three hours per week; level III, moderate physical activity or exercise between three and five hours per week; and level IV, more than five hours exercise per week or regular competitive sports.

The researchers also analyzed the genes of the participants to rule out any predisposition to heart disease which could possible cause heart changes; hearts were also measured using cardiac magnetic resonance (CMR).

The results showed that above a threshold of three hours, the more exercise you do, the more your heart is likely to adapt, with around one-third of participants taking part in three to five hours of exercise per week, and one in five of these individuals showing an increase in the thickness of the heart muscle and the volume of the heart chambers.

Of those who reported doing more than five hours of exercise a week, over half developed similar changes, with the team finding that the more the exercise these participants did, the more significant the changes.

The changes, which occur in tandem as the heart adapts to exercise, enable the heart to pump more blood and therefore supply the exercising muscles with more oxygen and nutrients. One of the study's lead researchers, Declan O'Regan, cautioned that these changes shouldn't be misdiagnosed as heart disease, when heart changes happen in isolation from each other.

The researchers now believe that an individual's activity level should be taken into account before diagnosing common heart conditions, and used along with a heart scan and other measures such as an ECG, to identify those with a heart problem.

The findings were published on Tuesday in the journal Circulation: Cardiovascular Imaging.