Mayo Clinic study: High-intensity aerobic exercise can reverse cellular aspects of aging

Everyone knows that exercise is good for you, but what type of training helps most, especially when you're older -- say over 65? A Mayo Clinic study says it's high-intensity aerobic exercise, which can reverse some cellular aspects of aging. The findings appear in Cell Metabolism.

Mayo researchers compared high-intensity interval training, resistance training and combined training. All training types improved lean body mass and insulin sensitivity, but only high-intensity and combined training improved aerobic capacity and mitochondrial function for skeletal muscle. Decline in mitochondrial content and function are common in older adults.

High-intensity intervals also improved muscle protein content that not only enhanced energetic functions, but also caused muscle enlargement, especially in older adults. The researchers emphasized an important finding: Exercise training significantly enhanced the cellular machinery responsible for making new proteins. That contributes to protein synthesis, thus reversing a major adverse effect of aging. However, adding resistance training is important to achieve significant muscle strength.

"We encourage everyone to exercise regularly, but the take-home message for aging adults that supervised high-intensity training is probably best, because, both metabolically and at the molecular level, it confers the most benefits," says K. Sreekumaran Nair, M.D., Ph.D., a Mayo Clinic endocrinologist and senior researcher on the study. He says the high-intensity training reversed some manifestations of aging in the body's protein function. He cautioned that increasing muscle strength requires resistance training a couple of days a week.

The study's goal was to find evidence that will help develop targeted therapies and exercise recommendations for individuals at various ages. Researchers tracked metabolic and molecular changes in a group of young and older adults over 12 weeks, gathering data 72 hours after individuals in randomized groups completed each type of exercise. General findings showed:

• Cardio respiratory health, muscle mass and insulin sensitivity improved with all training.
• Mitochondrial cellular function declined with age but improved with training.
• Increase in muscle strength occurred only modestly with high-intensity interval training but occurred with resistance training alone or when added to the aerobic training.
• Exercise improves skeletal muscle gene expression independent of age.
• Exercise substantially enhanced the ribosomal proteins responsible for synthesizing new proteins, which is mainly responsible for enhanced mitochondrial function.
• Training has little effect on skeletal muscle DNA energy transfer but promotes skeletal muscle protein expression with maximum effect in older adults.