HIIT (High-intensity interval exercise) is increasingly documented as a form of exercise that is beneficial and suitable for our modern lifestyles. For those short on time, a few minutes of HIIT or a few minutes of sprinting can be just as effective as much longer exercise sessions in boosting certain functions, including mitochondrial function essential for our cellular health (and youthfulness). This is the theme of this small study published in the American Journal of Physiology.
Mitochondria, these small powerhouses of cells, are essential for good health. Previous research has shown that exercise creates new mitochondria and improves the function of existing mitochondria. This change in mitochondrial function in response to a single exercise session generates signals that may induce beneficial changes in cells and reduce the risk of chronic disease. High-intensity interval exercise (HIIT) consists of short periods of high-intensity aerobic exercise, which will increase the heart rate, alternated with brief periods of recovery. Until this study, it was unknown whether the intensity of an intense workout can positively affect
This small study followed 8 young adult volunteers during cycling training, of varying intensity:
- moderate intensity: 30 minutes of continuous exercise at a maximum effort of 50%,
- HIIT: 5 sessions of 4 minutes at a maximum effort of 75%, each separated by a minute of rest,
- sprint: 4 sessions of 30 seconds at maximum effort, each separated by 4.5 minutes of recovery.
The research team measured the amount of energy participants expend during each training session and compared mitochondrial changes in thigh muscles before and after each session.
Reactive oxygen levels benefit cells: Researchers have found that levels of hydrogen peroxide – a type of molecule involved in cell signaling called 'reactive oxygen species' containing oxygen and hydrogen- are changed, in different parts of the mitochondria, after exercise. While too much reactive oxygen can be harmful to cells, here researchers find that the levels measured are the right amount to promote cellular responses beneficial to metabolic function.
A few minutes of intense exercise elicits mitochondrial responses similar to longer moderate-intensity activity. “Just two minutes of sprinting is enough to induce responses similar to 30 minutes of moderate-intensity aerobic exercise,” the researchers write.
Data suggesting that exercise can be tailored to individual preferences and constraints with the same benefit of these metabolic adaptations.
Important implications for adapting the practice of exercise to our lifestyles.
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