Over 40 but still want to do high-intensity workouts? Here's how to do it without harming your body
The midlife HIIT rules
Proving you really can have too much of a good thing, a new study has found that the benefits of the hugely popular HIIT workouts dwindle if you do them too often - and can even be harmful.
HIIT -which stands for high-intensity interval training - has been a fitness favourite for a while now, given its premise that short bursts of intense exercise burns more fat and build more muscle than longer, steadier workouts. Meaning more results in less time.
However, while the benefits of HIIT are widely known, is there a tipping point?
"There are countless types and formats of high-intensity training available without tested recommendations on how much is too much," says Jinger Gottschall, an associate professor of kinesiology at Penn State University in the US, who led the study.
"Individuals with a high volume of HIIT training were unable to reach their maximum heart rate regularly and complained of symptoms related to overtraining."
"It's one of the most popular types of exercise right now in gyms and classes," says UK-based personal trainer Matt Roberts, who has worked with Britain's former prime minister David Cameron and his wife Samantha.
"However, if it's not used appropriately, there's the risk of extreme overload, delayed onset muscle soreness (DOMS), injury and heart problems. Especially if you're new to fitness or over 40," says Matt (44).
So with that in mind, here are the midlife HIIT rules…
"HIIT training is a great way to train and it produces fantastic results for most people who use it, in terms of cardio gains, weight and fat loss and general gains in overall fitness and health," says Matt.
"However, if you're new to working out, don't do HIIT. Use a little interval training in your workouts, yes, do some weight training, yes, but don't do true HIIT. Not until you've been exercising fairly regularly for at least a month. After this you can start doing HIIT once a week and then after another month you can build up - if you wish - to doing it two or three times a week. It's not a good exercise for beginners."
"Even if you're reasonably fit and able to do HIIT without too many problems, three sessions a week is more than enough for most people, even very fit ones," says Matt. "Any more than that is probably too much."
This is in line with Professor Gottscall's study, whose findings were presented at the American College of Sports Medicine's annual conference, where she called for a weekly upper limit for HIIT fans.
Track your heart rate
Whether you use a Garmin, Fitbit or even the standard heart rate monitor on your phone, Matt says the easiest way to tell if you're overdoing it during a HIIT session is to invest in a fitness tracker. "These are a really good guide to whether you're pushing things a little too far," he says.
As a rule, HIIT workouts push your heart rate above 85pc of your maximum. "Raising your heart rate to 85-90pc of the maximum is fine," says Matt. "But only provided your recovery heart rate comes down to 65-70pc.
"The danger lies in not giving yourself sufficient recovery time between the peaks of intensity to get your heart rate down to this level.
"So give yourself an adequate rest period that is long enough for you, which varies from person to person, depending on their overall health and fitness levels.
"There is no one-size-fits-all with HIIT."
Don't push yourself (especially if you're a man)
"When men do HIIT - especially as they get older - there can be an issue with testosterone. It declines naturally with age, and as men get older there are two types of training that if you do them to the point of exhaustion, your body can't effectively use testosterone.
"One is too much endurance exercise, so things like marathon training. And the other is extreme high intensity interval training, like HIIT. So beyond a certain age, if you're a man and you do HIIT too often you can wear your body out so much it won't have the ability to regenerate testosterone levels."
Another reason to stick to the thrice-weekly limit.
Keep it short
The whole point of HIIT is short, but intensive bursts of fitness, so don't be tempted to prolong things. "I was surprised by the obvious difference between doing 30 to 40 minutes [of HIIT] and doing more than 45 minutes," says Professor Gottschall. "The difference in performance, stress-related feelings, and sleep quality was significant."
Matt says more than 40 minutes of high-intensity exercise can also increase your risk of injury and pain. "Thirty minutes of HIIT will give you similar, if not better, benefits to long, lower-intensity workouts. So don't be tempted to prolong your HIIT workouts, because they'll just become counterproductive - plus, you'll probably injure yourself."
Do yoga to complement HIIT workouts
"Teaching HIIT classes, I notice tightness in my shoulders and hips as well as my lower back, which is completely normal," says yoga teacher Chris Magee.
"So if I don't stretch once in a while my body feels very tight and my ability to move quickly in a HIIT class becomes more challenging.
"If you do too much of any one thing, your body can become adapted, locked with too much tension or weakness in certain areas which can lead to injury.
"Adding some yoga to your weekly workouts can help break down these patterns and release built up tension in the body. People often come to yoga for flexibility, but the more beneficial aspect to athletes is that of mobility, having full expanse and range of joints and muscles of the body, and having strength and control in that full range. Fitness should be the right balance of strength and stretching."
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