Eat right and exercise to slow the aging process. That’s good advice, but what you hear less about is the best WAY to exercise to keep your body youthful. For years, moderate-intensity cardio, like long-distance running or cycling, was the form of exercise most experts recommended, but times are changing. Now, time-expedient high-intensity interval training, or HIIT, is gaining favor.
Research shows HIIT builds cardiovascular endurance in the same way moderate-intensity exercise does, and some research shows it improves aerobic capacity (V02 max) more than moderate-intensity aerobic exercise. HIIT training is also effective for reducing body fat, especially belly and waist fat. In addition, when you do a high-intensity interval workout you get the benefits of the HIIT “after-burn” where you burn more calories and fat even after you finish your workout. Just as intriguing are the potential anti-aging benefits of HIIT training.
How HIIT Keeps You Youthful
One change that happens as you age is you produce less growth hormone. Along with the growth hormone decline comes an increase in body fat, especially visceral fat, deep abdominal fat that increases the risk for health problems like type 2 diabetes and heart disease. This age-related decrease in growth hormone is also linked with reduced cognitive function, declining bone health, and adverse changes in lipids and immune function.
What does all of this have to do with HIIT training? High-intensity interval training, because you do it at a high intensity, activates fast-twitch muscle fibers, “strength and power” fibers that stimulate the greatest increase in growth hormone. When you do moderate-intensity cardio, you’re mostly using slow-twitch fibers, ones that are optimized for endurance. You’ll get more aerobically fit by targeting slow-twitch fibers with moderate-intensity aerobic exercise, but you won’t get the same growth hormone “kick.”
HITT Training is Less Catabolic Because It’s Short in Duration
Some athletes try to boost their performance by injecting growth hormone, but you can get some of the benefits of this anti-aging hormone naturally with HIIT training. In contrast, long periods of moderate-intensity exercise, especially when you’re in a low energy state, boosts the release of cortisol, a hormone that blocks the release of growth hormone. Those long sessions of cardio may be working against you from an anti-aging standpoint.
One of cortisol’s main jobs is to make sure your muscle cells have enough glucose to use as fuel during periods of stress such as prolonged exercise. Once you’ve depleted muscle glycogen, the storage form of glucose, cortisol begins breaking down protein, including muscle protein, so the liver can use the amino acids to make new glucose. So, you may be losing more than body fat when you do long cardio workouts – you’re also tapping into the muscle you’re working so hard to maintain. It’s no secret we lose muscle with age and sarcopenia becomes a growing problem the older we get. Sarcopenia is one of the biggest age-related health issues people face after the age of 50 and one that contributes to loss of functionality.
Because HIIT workouts are shorter, they don’t trigger a sustained rise in cortisol, so muscle loss is less of an issue. Moderate-intensity cardio places your body into a catabolic state for a sustained period of time. Yes, you’ll burn fat, but also a certain degree of muscle. With HIIT training you get fat-burning, cardiovascular exercise with less time investment and less muscle breakdown. In fact, during high-intensity exercise, you’re using fast-twitch muscle fibers, ones optimized for strength and power. HIIT training can actually make you stronger and more powerful. Plus, high-intensity interval training leads to a greater rise in testosterone, another anabolic hormone, relative to steady-state exercise.
HIIT Training and Metabolic Health
With age, insulin sensitivity decreases. That’s one reason type 2 diabetes incidence goes up with age, and it becomes more difficult to lose weight. As cells become less sensitive to insulin, more insulin is released into your bloodstream and insulin resistance ensues. Estimates are that 60% of the population has some degree of insulin resistance. Insulin resistance is a risk factor for age-related problems like type 2 diabetes, heart disease and some forms of cancer. Research shows even short periods of high-intensity exercise boosts insulin sensitivity, which helps keep you metabolically healthy. HIIT training may be especially effective for people with insulin resistance and type 2 diabetes.
HIIT and Strength Training: A Good Anti-Aging Prescription
The other form of exercise that maximizes growth hormone and testosterone release is strength training. With strength training, you’re activating fast-twitch muscle fibers, the type of fibers we lose the most of with age. Resistance training using moderate to heavy resistance also boosts the synthesis of new bone, to help prevent age-related loss of bone mass. High-intensity resistance training is slightly better at improving bone health than moderate intensity. Just as importantly, strength training enhances strength and lean body mass to help prevent sarcopenia. HIIT and strength training are both important parts of an anti-aging exercise strategy.
Of course, you should allow your body enough rest and recovery time after a HIIT workout. Don’t try to do it every day. You can get the benefits doing it only 2 or 3 days per week.
The Bottom Line?
All forms of exercise offer health benefits, but high-intensity interval training may help you shed more visceral abdominal fat, prevent age-related loss of muscle tissue, preserve bone health and reduce insulin resistance. Combine physical activity with a whole food diet that contains adequate protein and you’ll increase your odds of being healthy and staying fully functional as you grow older. What could be more motivating than that?
Med Sci Sports Exerc 2007;39:665-71.
American Journal of Physical Medicine and Rehabilitation. 2012. Nov 9(11): 941-59.
Semin Reprod Endocrinol. 1999;17(4):311-25.
The Journal of Clinical Endocrinology and Metabolism. “Effect of low and high intensity exercise on circulating growth hormone in men.” (2013)
Calcified Tissue International, 66, 399-404.
Peak Fitness. “High-Intensity Interval Training May Help Slow Aging”
Hormones 2003, 2(4):243-249.
The Journal of Physiology, 590, 1077-1084. (2012)
J Endocrinol Invest. 2012 Dec;35(11):947-50.
BMC Endocr Disord. 2009; 9: 3.Published online 2009 Jan 28. doi: 10.1186/1472-6823-9-3
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