How Much Exercise Do You Really Need?

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You probably know zero exercise is not enough and that going for a walk every day is generally a good thing. And if you’re training for a marathon, you’ll be on your feet for a couple hours of hard workouts every week. But what is the benchmark for a human being just trying to squeeze enough healthy exercise into their life? Let’s break it down.

The basics: 150 minutes of cardio and two days of strength training every week

Fortunately, all the major public health organizations are in agreement. The World Health Organization, the Centers for Disease Control and Prevention, and the American Heart Association are all on board with the following guidelines for aerobic exercise:

• At least 150 minutes per week of moderate intensity (cardio) exercise like walking or easy jogging, or 75 minutes per week of vigorous exercise like running, or a combination. (If you can easily meet that, more is better.)

• At least two days per week of muscle strengthening activity, like lifting weights or doing other strength training like pushups, resistance band exercises, or even heavy manual labor like shoveling.

A previous edition of the guidelines said that you need to do your cardio for a minimum of 10 minutes at a time for it to count, but the current recommendation is to get it in however you can, even if that includes some shorter bursts here and there.

If that's too easy, level up to 300 minutes

If you’re pretty athletic, the above won’t sound like much. Good news! The WHO has set a secondary goal for folks like you. It’s simple: just do double the above. So you can aim for 300 minutes of moderate cardio, or 150 minutes per week of vigorous activity. Here's what that might look like:

• An intense, hour-long martial arts class three times a week (60 x 3 = 180, but this is vigorous cardio, so the minutes count double)

• Go on a 45-minute after-dinner walk every day (45 x 7 = 315 minutes of moderate cardio)

• Commute by bike to work, 20 minutes each way (40 minutes per day x 5 days per week = 200 minutes moderate cardio) and play recreational league soccer for two matches per week (50 minutes each game, for some combination of moderate and vigorous cardio, definitely puts us over 300).

What do "moderate" and "vigorous" exercise mean?

Walking at a purposeful pace counts as "moderate" cardio, and jogging counts as "vigorous." I have a detailed breakdown here of what exercises count as moderate versus vigorous. The distinction is not based on heart rate or effort level, but rather on a scientific metric called METs that relates to how much energy and oxygen the exercise takes. Moderate exercise is anything that scores between 3 and 6 METs, and vigorous exercise is 6+ METs.

That said, you can estimate by effort level. When you're doing moderate exercise, you'll be a little bit sweatier or breathing a little harder than when you're at rest, but you can do it continuously without feeling tired. It may not even feel like a workout. Here are some examples of moderate cardio:

• A brisk walk

• Commuting or doing errands by bike, on relatively flat ground

• Using a spin bike or other cardio machines like the elliptical, at a low intensity, steady pace

• Housework and light yard work, like washing windows or mowing the lawn with a power mower

By contrast, vigorous exercise includes activities where you're working hard and breathing hard. You might still be able to keep up a conversation, but it's not likely to feel easy. Vigorous exercise also includes the really hard stuff where you might not be able to keep it up very long. This could include:

• Running fast

• Bicycling uphill

• Pushing yourself to finish a Crossfit WOD with a good time

• Swimming laps

• Playing a game of soccer or basketball

• Tougher housework and yard work, like chopping wood or using a push mower

Can I combine moderate and vigorous cardio?

You can mix and match these two intensities. The math is simple if you think about 150 minutes as your target and consider every minute of vigorous cardio counting double. Here are some examples:

• A 20 minute brisk walk every weekday morning (20 minutes x 5 days = 100 minutes moderate cardio) plus a 30-minute spin class that has you working pretty hard (30 minutes counted double is 60; add that to the 100 and you're at 160 minutes).

• An hour of hiking, three days a week (60 minutes x 3 sessions = 180 minutes moderate cardio)

• Three 30-minute jogs (30 minutes x 3 = 90 minutes moderate cardio) plus a workout with 10 minutes easy jogging for a warmup and then 20 minutes of hard running, followed by a cooldown of another 10 minutes easy. (20 minutes vigorous x 2 is equivalent to 40 minutes moderate cardio, plus we can add the warmup and cooldown for another 20 moderate minutes). That gives you 150 total.

• Go for a 30-minute easy bike ride on Monday. Try a 45-minute water aerobics class on Wednesday. Take a short hike on Saturday. Mow the lawn for an hour on Saturday. (30 + 45 + 30 + 60 = 165 moderate cardio)

How much strength training do you need?

So far we’ve been talking about aerobic exercise, which is the kind where you’re continuously moving (or, perhaps, doing quick work/rest intervals) and your heart rate is up. But there are other important forms of exercise, too. The WHO and other organizations recommend two days per week of “high intensity muscle strengthening activity,” which includes anything where you’re thinking in terms of sets and reps. (Three sets of eight to 10 reps is a good structure to start.)

That activity can be anything that challenges your muscles, and where the last rep is a lot harder than the first. This could include lifting weights, or resistance band exercises, or bodyweight exercises like push-ups. So if you run three days per week and have time for more exercise, don’t just fit in extra runs; try adding two days in the weight room.

The strength training recommendations are for two days per week, per muscle group. If you like to work your upper body and lower body separately, that would mean two upper body days and two lower body days. If you prefer workouts that work all your muscles, you only need to do two of those full-body workouts per week (at minimum).

Can you get too much exercise?

What about an upper limit on how much exercise you get? There isn’t one, from a public health point of view. More is better. (And even if you are doing less than the recommendations, anything is better than nothing.) That said, it is always possible for you, as an individual, to do more exercise than your body is ready for. Don’t jump from a life of occasional strolling to a marathon training plan. (And if you are on that marathon training plan and you’re feeling worn down, take a break already.)