Effects of long-term physical activity on cardiac structure and function: a twin study

Area of Science:

• Cardiology
• Exercise Physiology
• Twin Studies

Background:

• Athletic training induces cardiac adaptations, but long-term effects considering genetic and environmental factors are less understood.
• Investigating the impact of sustained physical activity on cardiac structure and function is crucial for public health.

Purpose of the Study:

• To examine the long-term effects of physical activity versus inactivity on cardiac structure and function in genetically related individuals.
• To assess cardiac adaptations in twin pairs with a 32-year discordance in physical activity levels.

Main Methods:

• Studied 12 same-sex twin pairs (monozygotic and dizygotic) from the TWINACTIVE study, discordant for physical activity for 32 years.
• Measured resting echocardiography and electrocardiography at the end of the follow-up period.
• Quantified physical activity levels using MET hours/day, with active co-twins being significantly more active.

Main Results:

• Active co-twins exhibited a significantly lower resting heart rate (59 bpm) compared to inactive co-twins (68 bpm).
• No significant difference was observed in the heart rate-corrected QT interval between active and inactive co-twins.
• Trends indicated greater left ventricular mass per body weight and higher T wave amplitude in active co-twins, though not statistically significant (p=0.08).

Conclusions:

• The primary cardiac adaptation to long-term physical activity is a reduced resting heart rate, independent of genetic liability and childhood environment.
• Sustained physical activity leads to beneficial cardiac adaptations, including potentially increased left ventricular mass and altered T wave morphology.
• Twin study design effectively controlled for genetic and early-life environmental factors, isolating the impact of long-term physical activity.