By Dr. Mercola
At least half of all Americans do not engage in enough physical activity to prevent chronic diseases such as heart disease and diabetes, and on September 15, the US Surgeon General issued a new nationwide call to action:1,2 Walk more!
Please understand that I typically disagree with the conventional medical nonsense the Surgeon General often promotes. However, even a broken clock is right twice a day and this happens to be one of those times.
The call to "Step it Up" recognizes the responsibility of urban and city developers, urging communities to promote and design walk-friendly neighborhoods. In all, the five strategic goals presented by the Surgeon General include:
- Make walking a national priority
- Design communities that make it safe and easy to walk for people of all ages and abilities
- Promote programs and policies to support walking where people live, learn, work, and play
- Provide information to encourage walking and improve walkability
- Fill surveillance, research, and evaluation gaps related to walking and walkability
The Surgeon General even offers a playlist on Pandora3 to listen to during your walks, if you don't already have some favorite music to inspire you to get moving. However, the streaming service I use, Spotify, just added a pace matching running mode to its Android app.4
Make Walking a Priority, and Remember to Step Up the Pace Too
The recommendation to walk more didn't come out of the blue. It's been part of the public health policy for Americans since 2008, but inspiring people to get moving has been tough.
Federal guidelines recommend getting at least 2.5 hours a week of moderate intensity activity, such as brisk walking. Yet about 30 percent of adult men and women report getting only 10 minutes or so of physical activity per week!
Furthermore, as noted in a recent Medical Press article,5 getting people to step up the intensity of their activity has been an even greater challenge. But to reap the greatest benefit, your activity really needs to be done above a certain intensity.
The featured article6 offers the following advice to gauge the level of intensity of your activity, and how to use a fitness tracker to measure it for you:
"To measure activity intensity, a measure called the Metabolic Equivalent, or MET, is used. 1 MET is the rate of energy consumed by a person at rest (or watching television for example).
Moderate intensity activity is defined as activity that is between 3 to 5.9 METs of energy expenditure. This in turn equates to walking at a pace of 4.8 km per hour (3 miles per hour).
Devices like those from Fitbit track activities at, or above, this level activity as 'active minutes.' The target is set at 30 minutes a day and is recorded only if the wearer does more than 10 minutes at this intensity.
The accuracy of wearables to estimate METs is improved if they have a heart rate monitor built in...
[I]f you have a Fitbit (or other wearable), concentrate on the active minute target and less on the number of steps. Aim to get between 2.5 and 5 hours of active walking done a week.
If you don't have a wearable pedometer, another way of measuring the right level of intensity when walking is that you should have enough breath to be able to talk to someone but not be able to sing."
Diabetics Need Higher Intensity Activities
The recommendation to walk more and to take note of the intensity at which you move is particularly important for diabetics, as well as those who are insulin resistant or prediabetic, which means you're already well on your way toward developing diabetes.
In the UK, they specifically promote high-intensity interval training (HIIT) for diabetics,7 and for good reason.
A number of studies have highlighted the importance of HIIT as part of a successful treatment protocol against diabetes. In one such study,8,9 older overweight type 2 diabetics improved their glucose regulation in just six HIIT sessions done over the course of two weeks.
They also increased their mitochondrial capacity, which means their bodies became more effective at producing energy. Total time investment: 60 minutes per week. The key is intensity. In this study, participants performed 10 bouts of 60-second cycling at 90 percent of their maximum heart rate, interspersed with 60 seconds of rest.
While this may sound like too grueling a workout for someone who's overweight, out of shape, and/or older, HIIT researcher Dr. Martin Gibala, who has spent the last decade researching HIIT, claims most people do really well with this kind of exercise.
Another study10 (also co-authored by Dr. Gibala) used the same kind of HIIT program on sedentary but otherwise healthy middle-aged individuals. The only difference was that here, they exercised at 60 percent of their max heart rate rather than going all out.
Despite the reduction in intensity, they too were able to improve their insulin sensitivity and blood sugar regulation after just three sessions per week for two weeks.
In a follow-up study,11 people with full-blown type 2 diabetes saw improvement in blood sugar regulation for the next 24 hours following just one HIIT session at 90 percent of their max heart rate.
Just how minimal a time investment can you get away with, provided the intensity is high enough? Remarkable as it may seem, a fourth study found that just three minutes of HIIT per week for four weeks improved participants' insulin sensitivity an average of 24 percent!
Turn Your Daily Walk into a High Intensity Exercise
Many researchers are now starting to reemphasize the importance of walking. As noted by Katy Bowman,12 a scientist and author of the book: Move Your DNA: Restore Your Health through Natural Movement:
"Walking is a superfood. It's the defining movement of a human. It's a lot easier to get movement than it is to get exercise. Actively sedentary is a new category of people who are fit for one hour but sitting around the rest of the day. You can't offset 10 hours of stillness with one hour of exercise."
It is estimated that walking could prevent almost half of all diabetes cases. I believe high intensity walking could have an even greater effect, and it doesn't get a whole lot easier than picking up the pace of your walking. Best of all, just about anyone can do it, regardless of your age, weight, or fitness level.
In Japan, Dr. Hiroshi Nose and colleagues have developed walking programs for the elderly that incorporates bouts of higher intensity.13 His program calls for repeated intervals of three minutes of fast walking, aiming for an exertion level of about six or seven on a scale of one to 10, followed by three minutes of slow strolling.
Not only were elderly participants able to significantly improve their aerobic fitness and blood pressure after five months, walking for a mere 30 minutes three times a week; two years later, 70 percent of the participants were still adhering to the program and continued to reap sustained health benefits.14 Even if you're a younger person, this strategy can be an excellent entry into higher intensity training.
Daily Walking Is a Foundational Part Of a Healthy Lifestyle
Both research and experience confirm that walking is powerful medicine, and you can make it even more powerful by incorporating principles of high-intensity interval training. Simply alternating between speed-walking and slow strolling will allow you to maximize your rewards.
I believe aiming for 7,000 to 10,000 steps a day might be ideal for most people, and this is over and above your regular exercise program. If you're currently not doing anything in terms of fitness, please do consider getting more walking into your day. This in turn may spur you on to a more regimented fitness program, which would ideally include one to three HIIT sessions per week, such as that demonstrated below.
Core Principles of High-Intensity Interval Training
Following is a summary of what a typical HIIT routine might look like using either an elliptical machine or stationary bike:
- Warm up for three minutes
- Exercise as hard and fast as you can for 30 seconds. You want to get your heart rate up to your calculated maximum heart rate. The most common formula for this is to subtract your age from 220. You should be gasping for breath and feel like you couldn't possibly go on another few seconds. (In the beginning, you may opt for a lower threshold, like say 60 percent of your max heart rate, which you can then bump up to 80 or 90 as your fitness improves.)
- Recover for 90 seconds, still pedaling, but at slower pace and decreased resistance
- Repeat the high intensity exercise and recovery seven more times, for a total of eight repetitions. (In the beginning, you may only manage two or three repetitions. That's ok. Just keep adding reps until you reach a total of eight.)
This routine requires a mere 20 minutes of your time from start to finish, and only four minutes of that is spent in "all out" exercise. I typically cool down for another three to five minutes, and use a functional parameter of my heart rate. I like to get my heart rate down to around 120 before I stop, which gives me enough time to recover. I highly recommend using a heart rate monitor when doing these exercises as it is very difficult to accurately measure your heart rate without one.
Reverse Your Diabetes with Exercise, Diet, and Meal Timing
If you're diabetic or show signs of insulin resistance or prediabetes, the time to get moving is NOW. You may need to start slow and just aim for walking 10,000 steps a day, but eventually, you really need to consider bumping up the intensity. HIIT, even if it's just interval speed walking, is a really potent way to boost your insulin and leptin sensitivity, which is at the heart of your disease. Remember, while diabetes is a serious condition, it is reversible!
Naturally, in addition to ramping up physical activity, you also need to address the food you eat, as you cannot exercise your way out of a flawed diet. Some studies15 have shown that diabetics can significantly improve their health with exercise alone without making any dietary changes at all, but if you really want to get to the bottom of your condition and truly resolve it, I strongly advise you to make some basic dietary changes.
Unfortunately, you're not likely to get sound advice from most doctors or diabetes organizations. A primary reason for the failure of conventional diabetes treatment over the last 50 years has to do with seriously flawed dietary recommendations. Fructose, grains, and other sugar forming starchy carbohydrates are largely responsible for your body's insulin resistance, and sugars and grains — even "healthy" grains such as whole, organic ones, along with processed foods and trans fats — need to be drastically reduced, and swapped out for higher amounts of real food, including healthy fats and vegetables.
So, start cooking from scratch with fresh ingredients. Remember, processed foods are the main source of all the primary culprits, including high-fructose corn syrup and other sugars, processed grains, trans fats, artificial sweeteners, and other synthetic additives that may aggravate metabolic dysfunction.
If you have carefully followed the diet and exercise guidelines and still aren't making sufficient progress, I strongly recommend incorporating intermittent fasting. This effectively mimics the eating habits of our ancestors, who did not have access to grocery stores or food around the clock. They would cycle through periods of feast and famine, and modern research shows this cycling produces a number of biochemical benefits, including improved insulin/leptin sensitivity, lowered triglycerides, and other biomarkers for health and weight loss.