Mitochondria and aging: Why HIIT is the game-changer for fitness and longevity

The mitochondria are considered the ‘powerhouses’ or ‘engines’ of your cells. As Dr. Terry Wahls points out, most chronic diseases involve dysfunctional mitochondria. Poorly functioning mitochondria play a big role in disease risks, a slower metabolism, and the aging process. Researchers have concluded that exercise improves mitochondrial quality and function and stimulates mitochondrial turnover. It’s time to start thinking about these little organelles that have a big impact on our wellness and longevity.

Exercise for your mitochondria

Additional research also revealed that just 12 weeks of resistance exercise training yielded qualitative and quantitative changes in skeletal muscle mitochondrial respiration. Not only did resistance training increase lean body mass by 4% and quadriceps muscle strength by 15%, but staying committed to those 12 weeks of training also improved the respiratory capacity and functioning of the mitochondria.

So, which exercise is superior for improving mitochondrial functioning? Which exercise results in the most dramatic positive cellular changes? Let’s dive into the research.

The study

In a study published in Cell Metabolism, the researchers explored how different types of exercise — resistance training, high-intensity interval training (HIIT), or a mix of both — change muscles and cells at the molecular level in younger and older adults. The researchers focused on how genes and proteins respond to exercise, how exercise impacts the mitochondria, and how these changes affect overall fitness and metabolism.

The study methods

For 12 weeks, younger and older adults completed one of three exercise programs: traditional resistance training, HIIT, or a mix of both at a lower intensity. The researchers measured fitness and VO2 peak, insulin sensitivity, muscle mass and strength, mitochondrial health and function, and changes in gene activity and protein levels in muscle.

The results

Here are the study results:

• HIIT has the biggest impact in improving aerobic fitness, insulin sensitivity, and mitochondrial function, compared to other workouts. These results were especially noticeable for older adults.
• HIIT reversed some age-related declines in muscle mitochondria and enhanced the cell’s ability to make new proteins.
• HIIT enhanced mitochondrial capacity by close to 50% for young adults and nearly 70% in older adults.
• Resistance training mostly helped build muscle mass and strength, but didn’t have as much of an impact on aerobic fitness or mitochondria. The combined training resulted in smaller and moderate benefits compared to just doing HIIT alone.

Changes at the molecular level

HIIT caused significant increases in gene activity and protein-building machinery. Most of the benefits from exercise take place after the genes send their signals during the protein-building stage. HIIT improved protein quality and helped reduce damage to muscle proteins, which helps the body build new and efficient mitochondria.

Concluding thoughts

This study shows that HIIT is one of the most powerful ways to improve muscle health and fitness even in later years. This type of exercise, which involves shorter bursts or intervals of higher-intensity movements, is superior for the mitochondria and helps your body make more and better mitochondria, which can slow age-related decline and boost your energy levels.