Many people with the heart rhythm disturbance called atrial fibrillation (Afib) report poor quality of life and limitations on their activity. the upper chambers of the heart beat irregularly, often very fast. As a result, people may experience palpitations, shortness of breath or weakness. Although it sounds counter-intuitive, recent research suggests that high-intensity interval training (HIIT) can ease symptoms.
High-Intensity Interval Training for Atrial Fibrillation:
Researchers have long recognized that physical activity can improve quality of life for Afib patients. However, some people are understandably reluctant to spend hours every week on exercise. Moreover, cardiologists worried that vigorous exercise might complicate their arrhythmia.
A new randomized controlled trial compared high-intensity interval training to moderate intensity continuous training among 86 people with atrial fibrillation (JAMA Network Open, Oct. 31, 2022). High-intensity interval training improved resting heart rate and quality of life equally with substantially less time spent exercising. Specifically, those assigned to HIIT spent two 23-minutes sessions a week, compared to two hour-long sessions of moderate intensity continuous training.
How Is a HIIT Session Structured?
Each 23-minute session began with two minutes of warm-up at 50% of peak power. Participants then completed two 8-minute training intervals–30 seconds of maximum output (80 to 100%) interspersed with 30 seconds of active recovery. There were four minutes of rest between the two 8-minute blocks. Following this, after the second block, volunteers cooled down for one minute at 25% of peak power. They were using cycle ergometers, which made it possible to measure these fractions of peak power. Over the course of 12 weeks, the exercise demands increased, but so did the participants’ capacities for peak power output.
What Was the Moderate Intensity Workout Like?
The hour-long session started with 10 to 15 minutes warming up with aerobic exercise. Once warmed up, volunteers chose walking or jogging, an elliptical trainer, cycling or rowing and did that for 30 minutes. The exercise leaders urged them to work “somewhat hard,” keeping heart rate at least 67% of peak. Following that half hour, they took 15 minutes for stretching and strengthening exercises.
Functional capacity was measured by how far the study participants walked on an indoor track in six minutes. On average, people in the HIIT group went 21 meters further at the end of the study than at the beginning. Those in the moderate workout group also went further, about 13 meters.
The researchers reported only a few adverse events during the exercise sessions: two in the HIIT group and one in the moderate intensity group. On the other hand, more people in the HIIT group dropped out of the study. Some people apparently value efficiency, while others prefer a manageable level of effort.