By Dr. Mercola
When it comes to healthy habits, too much of a good thing can backfire, and that certainly applies to exercise. While most people get far too little exercise for optimal health, some do end up exercising too much — either by exercising too intensely for too long, and/or by working out too frequently.
Excessive exercise, especially if you're still focusing on traditional endurance cardio like long-distance running, can be particularly troublesome if you have a heart condition.
Both Forbes1 and Time Magazine2 recently highlighted research from Sweden and Germany showing that regularly exercising intensely for extended periods of time could do more harm than good in those with a history of heart disease.
That said, such warnings should not be taken as advice to stop exercising! It's important to remember that exercise has also been shown to prevent heart disease as effectively as medications. The take-home message here is that, to protect and optimize your heart health, you'll want to:
- Exercise safely and effectively. Research has clearly demonstrated that short bursts of intense activity is safer and more effective than conventional cardio—for your heart, general health, weight loss, and overall fitness
- Make sure you allow your body to sufficiently recover between sessions. An equation to keep in mind is that as intensity increases, frequency can be diminished
Recent research has given us a much better understanding of exercise physiology, and many of our past notions have been turned upside-down, in terms of how long and how hard you can push yourself without doing harm.
High-endurance training, such as running for an hour at a time, puts extraordinary stress on your heart. And while stressing a muscle usually makes it stronger, extremely high stress can have the opposite effect—and when it comes to your heart muscle, this can be bad news.
Excessive Exercise Can Put Heart Patients at Increased Risk
Studies have repeatedly demonstrated that extreme endurance exercise leads to high levels of oxidative stress, inflammation, and damage to your heart tissues. This produces acute physiological responses that can trigger a cardiac event. Now we can add two more studies to this growing list.
In the first, German researchers3, 4 followed more than 1,000 people in their 60s for 10 years. About 40 percent of them engaged in 60 minutes' worth of moderate-intensity aerobic exercise two to four times per week.
Of the remaining participants, half got an hour of exercise more than four times per week. The other half exercised less than twice a week—about one in 10 reported exercising rarely, if ever.
All of them had been diagnosed with coronary artery disease, but were in stable condition. Not surprisingly, those who exercised the least (less than twice a week) had the highest risk for both a cardiac event and all-cause mortality, compared to those who engaged in moderate exercise.
However, the most active patients also had an increased risk, doubling their risk of heart attack and stroke, compared to more moderate exercisers. As noted by the authors:
"...[W]hen taking time-dependence of physical activity into account, our data indicated reverse J-shaped associations of physical activity level with cardiovascular mortality, with the most frequently active patients also having increased hazards.
This study substantiated previous findings on the increased risks for adverse outcomes in physically inactive CHD patients. In addition, we also found evidence of increased cardiovascular mortality in patients with daily strenuous physical activity..."
The second study,5 conducted by Swedish researchers, suggests that excessive endurance exercise during younger years might increase your risk of developing heart problems later in life. Here, more than 44,400 men between the ages of 45 and 79 were surveyed about their exercise habits at age 15, 30, 50, and during the previous year. As reported by the featured article:6
"Those who exercised intensely for more than five hours a week were 19 percent more likely to have developed an irregular heartbeat, which is a key factor in stroke risk."
Short Bursts of Intense Activity Appear to Be Safer for Your Heart
Not only have other studies confirmed that excessive endurance cardio takes a heavy toll on your heart, they've also concluded it's one of the least efficient forms of exercise. Over the past 30 years, the number of people running marathons has increased 20-fold, while obesity has tripled. Indeed, many who take up running in order to lose weight end up dismayed at the lack of results.
High-intensity interval training (HIIT), on the other hand, has proven to be far more efficient and effective—and safer for your heart as well. Part of the reason for this is because it mimics the movements of our hunter-gatherer ancestors, which included short bursts of high-intensity activities, but not long-distance running.
An added boon is that you can complete an entire HIIT session in 20 minutes, and you only need to do them twice or three times a week. Any more than that and you'll actually be overdoing it. It makes sense that your body was hardwired for intermittent, high intensity activity, and research supports the notion that HIIT recreates exactly what you need for optimal health. Twice-weekly, 20-minute long sessions can help you:
- Lower your body fat
- Improve your muscle tone
- Boost your energy and libido
- Improve athletic speed and performance
Intensity and Recovery—Two Key Factors to Get the Most from Your Workout
HIIT is core part of my Peak Fitness program, which Phil Campbell was instrumental in helping me develop. Briefly, a Peak Fitness routine typically includes the following. (For a demonstration, please see the videos below).
- Warm up for three minutes
- Exercise as hard and fast as you can for 30 seconds. You'll want to raise your heart rate to your anaerobic threshold, and to do that, you have to give it your all during these 30-second intervals. (As a general guideline, you can calculate your anaerobic threshold by subtracting your age from 220)
- Recover for 90 seconds
- Repeat the high intensity exercise and recovery cycle seven more times
If you have a chronic disease, you will, of course, need to tailor your exercise routine to your individual scenario, taking into account your stamina and current health. For example, you may need to exercise at a lower intensity, for shorter durations, or with lesser frequency. At the outset, you may only be able to do a couple of repetitions, and that's okay too. Slowly work your way up to eight repetitions.
Besides intensity, recovery is a keyfactor of high intensity workouts. As mentioned earlier, as your intensity increases, you typically need to decrease the frequency, to ensure your body has time to repair and recuperate between sessions. For this reason, it is NOT recommended to do high intensity exercises more than three times a week. Both Phil Campbell and Dr. Doug McGuff have addressed this in previous interviews.
It's also important to give your body the nutrients it needs to repair and recover. Consuming a fast-assimilating protein such as 10-20 grams of high-quality whey protein within 30 minutes of your workout will bring your muscles out of their catabolic state and supply them with the nutrients they need for repairs. Processed carbs or fructose-laden sports drinks should be avoided at all costs, as these will nullify many of the benefits of exercise. As just one example, consuming fructose (including that from fruit juices) within two hours of a high-intensity workout will decimate your natural human growth hormone (HGH) production, which is a MAJOR benefit of interval training.
Seven Signs You May Be Overdoing It
When you perform high intensity training, it's very important to carefully consider the frequency of your sessions to give your body enough time to recover in between. If you don't, the exercise has the potential to do more harm than good. To really maximize your workout efforts, you'll want to strive for that "Goldilocks' Zone" where you're pushing hard enough to challenge your body at your current level of fitness, while allowing your body to recuperate in between.
Again, if you're doing high intensity interval exercises, it's NOT recommended to do them more than three times a week. I currently do elliptical Peak Fitness twice a week and some high intensity work with a personal trainer involving body movements and light weights once a week. If you're unsure whether you may be pushing yourself too hard, the following seven symptoms may signal that you need to cut back a bit and allow your body to recover between sessions:
- Exercise leaves you exhausted instead of energized
- You get sick easily (or it takes forever to get over a cold)
- You have the blues
- You're unable to sleep or you can't seem to get enough sleep
- You have ''heavy'' legs
- You have a short fuse
- You're regularly sore for days at a time
For Optimal Health, Add Variety to Your Workout, and Beware of Excessive Sitting
The take-home message here is that one of the best forms of exercise to protect your heart is short bursts of exertion, followed by periods of rest. By exercising in this way, you recreate exactly what your body needs for optimum health. Heart attacks, for example, don't happen because your heart lacks endurance. They happen during times of stress, when your heart needs more energy and pumping capacity, but doesn't have it. So rather than stressing your heart with excessively long periods of cardio, give interval training a try—just be sure you're fully recovered in between sessions. If you experience any of the seven warning signs listed above, cut back a bit.
During any type of exercise, as long as you listen to your body, you shouldn't run into the problem of exerting yourself excessively. And, with interval training, even if you are out of shape you simply will be unable to train very hard, as lactic acid will quickly build up in your muscles and prevent you from stressing your heart too much. That said, intense exercise should also be balanced with strength training, proper stretching, core strengthening, stress reduction, good sleep, and an optimal nutrition plan. You'll find much more information about HIIT and other types of exercise in the fitness section of my website. Of equal, if not greater importance, is to avoid being too sedentary in general, between workout sessions.
Compelling research now tells us that prolonged sitting can have a tremendously detrimental impact on your health even if you exercise regularly. The reason for this is because your body needs to interact with gravity in order to function optimally. Most recently, an Australian study7 warned that inactivity is the greatest heart risk factor in women over 30—beating out other well-known risk factors like smoking, obesity, and high blood pressure. As reported by Reuters:8
To counteract the ill effects of sitting, make sure to get out of your chair every 15 minutes or so. To learn more about the benefits of intermittent movement, please see my interview with NASA scientist Dr. Joan Vernikos. Personally, I usually set a timer for 15 minutes while sitting, and then stand up and do one legged squats, jump squats, or lunges when the timer goes off. The key is that you need to be moving all day long, even in non-exercise activities. I make it a habit to set a timer for 15 minutes and get up and do about a minute or so of exercise to break up my sitting sessions. I would strongly encourage you to do the same. You can get a start by reviewing the recent article I did on this with loads of different video examples.
"Based on rates of death from heart disease in Australia, the researchers calculated that if all the women represented by the study population could do about one hour of moderately intense activity a day, some 2,612 deaths would be avoided. That's more Australian women than are killed in road accidents each year..."