By Dr Joseph Mercola
Eighty percent of Americans fail to meet the recommended amount of exercise, which is 2.5 hours of moderate-intensity activity or 1.25 hours of vigorous-intensity activity each week… along with twice weekly strength-training workouts.
These are the “official” US government exercise recommendations, but they are not the last word on fitness. How much exercise you need depends on a number of factors, not the least of which is the type of activity you do. The more intense you work out, the less frequently you should do it (and the shorter the duration should be).
Wondering how to get maximum exercise benefits in minimal time? It’s entirely possible to get a phenomenal workout in just 20 minutes two or three times a week if you’re using, for instance, high-intensity interval training (HIIT) or super-slow weight training. But this doesn’t mean you should simply sit around for the rest of the week.
Regular walking (upwards of 7,000 steps a day) is also important, in addition to regular exercise. But before I get into the details, here’s something you should know: even small amounts of exercise matter… and any amount of exercise is better than none at all.
When you exercise intensely, you can reap greater rewards in a shorter period of time. For starters, high-intensity interval training burns more calories in less time – a mere 2.5 minutes, divided into five 30-second sprint intervals at maximum exertion, each followed by four minutes of light pedaling to recuperate, can burn as much as 220 calories.
Besides burning more calories, HIIT has also been shown to produce greater health benefits overall than conventional aerobic training, such as increasing insulin sensitivity and glucose tolerance – both of which are critical components of optimal health.
One study that found doing just three minutes of high-intensity exercise per week for four weeks could lead to a 24 percent improvement in insulin sensitivity.
Another important benefit of high-intensity interval training is its ability to naturally increase your body’s production of human growth hormone (HGH), also known as “the fitness hormone.”
HGH is a synergistic, foundational biochemical underpinning that promotes muscle and effectively burns excessive fat. A study published in the journal Cell Metabolism even showed that when healthy but inactive people exercise intensely, even if the exercise is brief, it produces an immediate change in their DNA.
While the underlying genetic code in the muscle remains unchanged, exercise causes important structural and chemical changes to the DNA molecules within your muscles. This contraction-induced gene activation appears to be early events leading to the genetic reprogramming of muscle for strength, and to the structural and metabolic benefits of exercise.
Several of the genes affected by an acute bout of intense exercise are genes involved in fat metabolism. Specifically, the study suggests that when you exercise, your body almost immediately experiences genetic activation that increases the production of fat-busting proteins HIIT also plays an important part in promoting overall health and longevity. This too is something you cannot get from conventional, aerobic endurance training. Other benefits associated with high-intensity interval training include decreased body fat, increased sexual desire, better muscle tone and firmer skin.
The HIIT approach I personally use and recommend is the Peak Fitness method, which consists of 30 seconds of maximum effort followed by 90 seconds of recuperation, for a total of eight repetitions. Super Slow strength training is another high-intensity exercise, which may even be more effective than Peak Fitness cardio. While they both are highly effective, you can generate a higher cardiac output with Super Slow training as discussed in my interview with Dr. McGuff.
By slowing your movements down, you’re actually turning them into high intensity exercise. The super-slow movement allows your muscle, at the microscopic level, to access the maximum number of cross-bridges between the protein filaments that produce movement in the muscle. You can perform the super-slow technique with hand weights, resistance machines, bodyweight exercises, or resistance bands.
You only need about 12 to 15 minutes of super-slow strength training once a week to achieve the same HGH production as you would from 20 minutes of Peak Fitness sprints, which is why fitness experts like Dr. Doug McGuff are such avid proponents of this technique. The key to making this work for you is intensity, which needs to be high enough that you reach muscle fatigue. If you’ve selected the appropriate weight for your strength and fitness level, your goal is to have enough weight that you cannot do more than 12 reps, but not so much that you can’t complete at least four. Ideally, you will be somewhere in the neighborhood of seven to eight.
When the intensity is this high, you can decrease the frequency of your strength training sessions. In fact, the higher your fitness level, the less often you should do them. I also recommend incorporating Buteyko breathing, which involves breathing only through your nose while working out. This raises the challenge to another level. As a guideline, when you start out, allow your body at least two days to rest, recover, and repair between high-intensity sessions, and do not exercise the same muscle groups each time.
As your strength and endurance increases, decrease how often you do the sessions, as each one is placing greater stress on your body (provided you keep pushing yourself to the max). As a rule, avoid doing high-intensity exercises more than twice or three times a week. You can enjoy other activities on the off-days, such as swimming, Pilates, yoga, biking,gardening, or whatever other activities tickle your fancy. I also encourage you to use a pedometer and walk as much as possible, ideally 7,000 to 15,000 steps daily.
Not Exercising May Be Worse Than Smoking
If you’re looking for motivation to get moving, consider this: research shows that inactivity is lined to more than 5 million deaths each year, which is similar to the death toll taken by smoking. Data also suggests that at least twice as many deaths occur due to a lack of exercise than due to obesity. This is really astounding, considering one in five US deaths are associated with obesity. Study author Ulf Ekelund from the Medical Research Council Epidemiology Unit at the University of Cambridge told TIME:
“This is a simple message: just a small amount of physical activity each day could have substantial health benefits for people who are physically inactive.”
As stated by Dr. Timothy Church, director of preventive medicine research at the Pennington Biomedical Research Center in Baton Rouge, exercise indeed affects your entire body—from head to toe—in beneficial ways.d This includes changes in your:
- Muscles, which use glucose and ATP for contraction and movement. Tiny tears in your muscles make them grow bigger and stronger as they heal. Gaining more muscle through resistance exercises has many benefits, from losing excess fat to maintaining healthy bone mass and preventing age-related muscle loss as you age. The intensity of your resistance training can achieve a number of beneficial changes on the molecular, enzymatic, hormonal, and chemical level in your body.
- Lungs. As your muscles call for more oxygen, your breathing rate increases. The higher your VO2 max—your maximum capacity of oxygen use—the fitter you are.
- Heart. Your heart rate increases with physical activity to supply more oxygenated blood to your muscles. The fitter you are, the more efficiently your heart can do this, allowing you to work out longer and harder. Your blood pressure will also decrease as a result of new blood vessels forming.
- Brain. The increased blood flow also benefits your brain, allowing it to almost immediately function better. Exercising regularly also promotes the growth of new brain cells, boosting your capacity for memory and learning. A number of neurotransmitters are also triggered, such as endorphins, serotonin, dopamine, glutamate, and GABA. Some of these are well-known for their role in mood control. Exercise, in fact, is one of the most effective prevention and treatment strategies for depression.
- Joints and Bones. Exercise can place as much as five or six times more than your body weight on them. Weight-bearing exercise is one of the most effective remedies against osteoporosis, as your bones are very porous and soft, and as you get older your bones can easily become less dense and hence, more brittle — especially if you are inactive.
The simple take-home message is this: if you are currently living a sedentary lifestyle, the mere act of incorporating some high-intensity activity two or three days a week, along with regular walking, can significantly reduce your mortality rate.
Main image: Wikicommons
About Dr. Mercola
Dr. Joseph Mercola finished his family practice residency in 1985 but was trained by the conventional model. In his first years of private practice, he treated many symptoms with prescription drugs and was actually a paid speaker for the drug companies.
But as he began to experience the failures of this model in his practice, he embraced natural medicine and has had an opportunity over the last thirty years to apply these time tested approaches successfully with thousands of patients in his clinic.
Over 15 years ago he founded Mercola.com to share his experiences with others. The site is the most visited natural health site in the world for the last seven years with nearly two million subscribers. He’s also written two NY Times bestselling books, and has had frequent appearances on national media including the Dr. Oz show and major news channels.