It’s not enough to walk the dog. That is to say, there are several components to a well-executed exercise plan or prescription. For most of us, walking at 2-3 mph would best be categorized as an “activity of daily living” rather than exercise.
One reason to exercise is to improve or maintain cardiorespiratory fitness. The World Health Organization recommends a minimum of 150 minutes of moderate exercise per week, or 75 minutes of “vigorous” activity. However, the American Heart Association is now recommending 300 minutes per week, and a JAMA review article in 2015 highlighted that for longevity benefits, while 150 minutes reduced all-cause risk of death by 31%, 450-700 minutes per week resulted in a 39% decreased risk of death. If you are doing the math, that is approximately 1 hour per day. There is no question that moderate to intense cardio-aerobic exercise is a powerful longevity tool, and in fact, fitness is a better predictor of lifespan than cardiovascular risk factors and labs. The heart rate must rise to 60-70% of your heart rate maximum (something we call zone 2 training) in order to count.
However, there is another reason to exercise, and another type of exercise, that is key to stave off functional disability, muscle atrophy, falls, and sports injuries. We can call this resistance exercise, or strength training, or musculoskeletal exercise. The purpose of building strength is to maintain mobility in our later years, maintain our bone density, improve our metabolic conditioning, facilitate fat loss, and importantly, to increase insulin sensitivity. Strength training is a metabolic stimulus that pulls glucose back into muscle glycogen, rather than having it float around and end up in the liver, where it is much more likely to convert to lipid (fats). The liver can circulate these fats as damaging lipoproteins or as triglycerides headed for fat storage depots. And fatty liver (called “NASH”- non-alcoholic steatohepatitis) is currently the most common form of liver disease worldwide and a precursor lesion of cirrhosis. So, strength training is important for our structural integrity but also for our metabolic fitness (ability to manage glucose and insulin, and maintain lower body fat).
A carefully planned strength program can be executed in a twice-a-week format taking no longer than an hour total for the week. If most of the exercises are compound (think total body or multiple muscles involved) all of the important muscles of posture and movement can be worked adequately. An ultra-minimalist program could be just a leg press and a pull-down type of movement. (3 sets of 10-15, to muscle failure or loss of form). The magic of strength training occurs hours and days after the session, as the muscle fibers rest and repair from the overload. As we get older, our time to recover gets longer, meaning we may not need or want to strength train more frequently than when we were younger. As part of a longevity consult, we will create a strength prescription that works for you, as well as educating you on the proper amount and timing of dietary protein that allows for muscle fiber synthesis. As a bonus, and soon to be featured in another blog, we now know that exercise has a direct effect on senescent cells (aged, damaged) to reverse one of the nine major hallmarks of aging. So, exercise, either type, can be viewed as the ultimate “senolytic” treatment…an active purge of geriatric cells in the body. If you are committed to a longevity program, movement is one of your top tools. We can help design a program to fit your body and your schedule.