Exercise, Why It Really Is the Key to Longevity

exercise and mitochondrial health

Everyone understands that exercise is important, yet they don’t seem to grasp the multiplicity of health benefits physical movement imparts. Moreover, it seems many people feel that exercise is unnecessary as long they follow a healthy diet. Don’t get us wrong, a healthy diet is certainly paramount to longevity, but it will never replace the need for a concerted exercise regimen.

By the same token, no amount of drugs or over-the-counter supplements will ever replace diligent exercise. Thus, it’s pertinent to make physical fitness a priority for improving your health and longevity. But we’re not just talking about any type of exercise, we’re talking specifically about diligent, vigorous training.

Unlocking Your Health Potential with Movement

At its most basic, physical movement is a means of burning calories (energy). Thus, even when you get up to walk outside and grab the daily newspaper, your body uses biomechanical energy to fuel those few steps. This is why step and fitness trackers, like the FitBit, have become a craze as of late, since research suggests that walking at least 10,000 steps per day (which is roughly five miles) improves longevity.

However, the physiological benefits of simply walking a few thousand steps per day are minimal when compared to exercise that requires more intense physical exertion. In simpler terms, walking is merely a way to burn a few calories with little downstream benefit.

On the contrary, the beneficial metabolic adaptations of high-intensity exercise are so numerous it’s almost impossible to cover them all in one article (don’t worry though, we will cover the most significant benefits herein).

Do note before moving on that this article is not implying that low-intensity exercise, such as walking, is inherently not beneficial for health. Going for a walk after a long day at the office is certainly a good idea, especially if you have physical limitations that impede your ability to exercise vigorously. Nevertheless, the longevity benefits of intense exercise far outweigh those of low-intensity exercise (both anecdotally and in research).

Physiological Benefits of Vigorous (High-Intensity) Exercise

Before we dive into the many benefits of vigorous exercise, it’s necessary to understand what this type of exercise entails. In scientific literature, High-intensity Exercise Training (HIET)” is described as exercise performed at or above the lactate/lactic acid threshold.

As such, HIET relies predominantly on anaerobic respiration, which uses glucose to produce energy (and lactic acid as a byproduct). Lactic acid is that pesky molecule that is responsible for the “burning” sensation you feel in your muscles after vigorously exerting yourself for as long as possible.

For example, the lactic acid buildup in your leg muscles when you sprint as fast as possible, or in your chest when you bench press a heavy barbell, is ultimately what inhibits your ability to continue that exercise at max capacity for much more than 20 seconds, or a few repetitions, respectively. Contrast that with low-intensity exercise (walking) which you could do for possibly hours on end with no issue (because it’s not intense enough to produce lactic acid).

Going forward, the benefits discussed herein come from research examining subjects that undergo vigorous exercise/HIET.

Vigorous Exercise Increases Mitochondrial Biogenesis (and Metabolic Rate)

Mitochondria are organelles that act as the “powerhouse” of cells, and are where the electron transport chain occurs. The process of mitochondrial biogenesis is where cells increase their mitochondrial content. Mitochondria are key regulators of metabolic rate as they are home to uncoupling proteins (UCPs) that modulate thermogenesis.

Research has shown that skeletal muscles undergo mitochondrial biogenesis after high-intensity exercise (but not low-intensity exercise).[iii]Moreover, UCP expression increases dramatically in muscle tissue – upwards of 8-fold – shortly after vigorous exercise (and remains elevated for 24 hours thereafter).[iv]

In short, by training vigorously (for even just 20 minutes) will elevate your metabolic rate at rest for many hours after exercise takes place.

Vigorous Exercise Increases Growth Hormone and Testosterone

Shortly after high-intensity strength and endurance training, the endocrine system undergoes a variety of changes.[v] For starters, growth hormone secretion increases significantly; this is key for longevity and healthy body composition as growth hormone is associated with longer life span and is also a potent fat-burning hormone (since it increases fatty acid oxidation).[vi]

Moreover, testosterone levels increase after vigorous exercise, and remain elevated as long as intense training remains constant.[vii] Testosterone is the most potent anabolic hormone in humans, and is also associated with longer life span.[viii]

In fact, low testosterone levels has become quite an epidemic, with many males resorting to doctors to treat the issue via testosterone injections. Lack of intense physical exercise may very well be an underlying cause of low testosterone levels, but this is ultimately good news as the issue can be reversed after a concerted exercise regimen is set in place.

Vigorous Exercise Enhances Insulin Sensitivity

“Insulin resistance” is a term denoting that your cells have become ‘numb’ to the main role of insulin (i.e. remove glucose from the blood). If your body is resistant to the effects of insulin, then you eventually reach a state where insulin levels are chronically elevated. Eventually, this manifests into type-2 diabetes, meaning your body no longer utilizes carbohydrates properly.

Contrarily, having high “insulin sensitivity” means your body responds appropriately to insulin signaling. Vigorous exercise in both healthy subjects and even type-2 diabetics has been shown to dramatically increase carbohydrate utilization/insulin sensitivity.[ix],[x] Basically, training intensely means you can “get away with” eating some starchy foods without having to worry your body will store them as fat.

Vigorous Exercise Improves Heart Health and Blood Lipid Profiles

A 24-week human trial separated subjects into either moderate-intensity exercise or high-intensity exercise treatments. The two treatments were matched for total calories burned. The findings showed high-intensity training is more effective in improving cardiorespiratory fitness and blood lipid profiles than moderate-intensity training (despite equal calorie burn between the two groups).[xi]

This further reinforces that vigorous exercise induces metabolic adaptations that aren’t replicated by lower intensity forms of exercise. Also, don’t forget that your heart is ultimately a muscle, and needs to be trained for optimal function. Research confirms that high-intensity exercise is indubitably the most effective way to enhance your heart’s efficiency.

Vigorous Exercise Decreases Telomere Shortening

Telomeres are short noncoding sequences found at the end of chromosomes. The length of telomeres is a crucial measure of longevity as they shorten each time cells replicate. Research seems to suggest modest amounts of vigorous exercise may actually increase the activity of the enzyme telomerase, which can actually extend telomeres (theoretically reversing the aging process).[xii] This is likely one of the most significant mechanisms by which intense exercise can extend lifespan.

Vigorous Exercise Decreases Waist Circumference and Visceral Fat Tissue

Visceral fat tissue is the fat that surrounds internal organs and lies under subcutaneous fat (think “beer belly”). Excessive visceral fat tissue has consistently been associated with elevated levels of blood triglycerides (i.e. hypertriglyceridemia), which is a major risk factor for cardiovascular disease.[xiii]

Moreover, organ (especially the pancreas and liver) inflammation, decreased growth hormone, insulin resistance, and secretion of proinflammatory adipokines have all also been associated with excess visceral fat tissue.[xiv], [xv]

Essentially, if your health and longevity mean much to you, then carrying a lot of visceral fat is likely antagonizing your goals. Positively though, a study by Slentz et. al found a significant negative correlation between visceral fat tissue and serum growth hormone levels among individuals in that trained to their anaerobic/lactate threshold.[xvi] In layman’s terms, vigorous exercise decreases visceral fat tissue.

Moreover, the anaerobic threshold group had increased resting basal metabolic rate and significantly decreased weight circumference. Not surprisingly, both the “Low-intensity Exercise Training (LIET)” and “No Exercise” groups actually exhibited decreased basal metabolic rate and minimal change in waist circumference.


In the long-term, high-intensity exercise is not only more beneficial for longevity, but also less time consuming. Rather than slaving away on the treadmill for two hours, you’re better off doing a couple all-out sprints or any form of exercise that pushes you to your lactate threshold. Even as little as five 100-yard sprints can have significant impact on your physiology (and longevity), and will take less than 20 minutes to complete for most people.

Of course, there’s one thing that tends to scare people away from high-intensity exercise: it burns! Just keep in mind that the payoff is well worth it. Maybe there is some inherent truth to the old adage, “No pain, no gain,” after all.

[i] Gregg, E. W., Gerzoff, R. B., Caspersen, C. J., Williamson, D. F., & Narayan, K. V. (2003). Relationship of walking to mortality among US adults with diabetes. Archives of internal medicine, 163(12), 1440-1447.

[ii] Gibala, M. J., Little, J. P., MacDonald, M. J., & Hawley, J. A. (2012). Physiological adaptations to low‐volume, high‐intensity interval training in health and disease. The Journal of physiology, 590(5), 1077-1084.

[iii] Little, J. P., Safdar, A., Wilkin, G. P., Tarnopolsky, M. A., & Gibala, M. J. (2010). A practical model of low‐volume high‐intensity interval training induces mitochondrial biogenesis in human skeletal muscle: potential mechanisms. The Journal of physiology, 588(6), 1011-1022.

[iv] Jiang, N., Zhang, G., Bo, H., Qu, J., Ma, G., Cao, D., … & Zhang, Y. (2009). Upregulation of uncoupling protein-3 in skeletal muscle during exercise: a potential antioxidant function. Free Radical Biology and Medicine, 46(2), 138-145.

[v] Kraemer, W. J., Patton, J. F., Gordon, S. E., Harman, E. A., Deschenes, M. R., Reynolds, K. A. T. Y., … & Dziados, J. E. (1995). Compatibility of high-intensity strength and endurance training on hormonal and skeletal muscle adaptations. Journal of applied physiology, 78(3), 976-989.

[vi] Besson, A., Salemi, S., Gallati, S., Jenal, A., Horn, R., Mullis, P. S., & Mullis, P. E. (2003). Reduced longevity in untreated patients with isolated growth hormone deficiency. The Journal of Clinical Endocrinology & Metabolism, 88(8), 3664-3667.

[vii] Craig, B. W., Brown, R., & Everhart, J. (1989). Effects of progressive resistance training on growth hormone and testosterone levels in young and elderly subjects. Mechanisms of ageing and development, 49(2), 159-169.

[viii] Horstman, A. M., Dillon, E. L., Urban, R. J., & Sheffield-Moore, M. (2012). The role of androgens and estrogens on healthy aging and longevity. Journals of Gerontology Series A: Biomedical Sciences and Medical Sciences, 67(11), 1140-1152.

[ix] Dunstan, D. W., Daly, R. M., Owen, N., Jolley, D., De Courten, M., Shaw, J., & Zimmet, P. (2002). High-intensity resistance training improves glycemic control in older patients with type 2 diabetes. Diabetes care, 25(10), 1729-1736.

[x] Henriksen, E. J. (2002). Invited review: Effects of acute exercise and exercise training on insulin resistance. Journal of Applied Physiology, 93(2), 788-796.

[xi] O’Donovan, G., Owen, A., Bird, S. R., Kearney, E. M., Nevill, A. M., Jones, D. W., & Woolf-May, K. (2005). Changes in cardiorespiratory fitness and coronary heart disease risk factors following 24 wk of moderate-or high-intensity exercise of equal energy cost. Journal of applied physiology, 98(5), 1619-1625.

[xii] Kadi, F., Ponsot, E., Piehl-Aulin, K., Mackey, A., Kjaer, M., Oskarsson, E., & Holm, L. (2008). The effects of regular strength training on telomere length in human skeletal muscle. Medicine & Science in Sports & Exercise, 40(1), 82-87.

[xiii] Katsuki, A., Sumida, Y., Urakawa, H., Gabazza, E. C., Murashima, S., Maruyama, N., … & Adachi, Y. (2003). Increased visceral fat and serum levels of triglyceride are associated with insulin resistance in Japanese metabolically obese, normal weight subjects with normal glucose tolerance. Diabetes care, 26(8), 2341-2344.

[xiv] Fontana, L., Eagon, J. C., Trujillo, M. E., Scherer, P. E., & Klein, S. (2007). Visceral fat adipokine secretion is associated with systemic inflammation in obese humans. Diabetes, 56(4), 1010-1013.

[xv] Banerji, M. A., Faridi, N., Atluri, R., Chaiken, R. L., & Lebovitz, H. E. (1999). Body composition, visceral fat, leptin, and insulin resistance in Asian Indian men. The Journal of Clinical Endocrinology & Metabolism, 84(1), 137-144.

[xvi] Slentz, C. A., Aiken, L. B., Houmard, J. A., Bales, C. W., Johnson, J. L., Tanner, C. J., … & Kraus, W. E. (2005). Inactivity, exercise, and visceral fat. STRRIDE: a randomized, controlled study of exercise intensity and amount. Journal of Applied Physiology, 99(4), 1613-1618.