No one goes to the gym with the plan of wasting time. You want to make the most of it. But training non-stop for an hour doesn’t make sense either, and when you’re doing cardio intervals, taking a break isn’t just encouraged, it’s required. However, a common mistake is taking too much time to recover between cardio bursts.
Exerting energy during exercise creates fatigue, and one of the measures of physical fitness is your ability to continue working out without allowing your speed, power, or intensity to diminish the more tired you get. One way to improve this is by pushing yourself and working out with intensity even when you’re getting tired. Over time, this will help your body become more efficient at delivering fresh oxygen to your muscles. Of course, losing a little steam over the course of a gym session is totally normal, but if you give yourself too much rest between exercises, it allows your heart rate to drop out of the moderate-intensity zone (that's the zone you should aim to stay in during these particular rest intervals) which means you’re not getting the cardiovascular challenge you need to get you to the next level.
The solution? Plan strategic rest intervals based off the type of workout you’re doing. (The big asterisk to this is super-heavy lifts that you could physically only do one at a time, otherwise known at your one rep max—for example, Olympic weight lifting. In this case you should take several minutes of rest because you're training different muscle fibers.)
Exactly how much you should rest varies depending on the modality, as well as individual fitness level. But here are some general guidelines on how much rest you should take as a starting point for your next workout.
We recommend starting with a 1:2 work to rest ratio for high-intensity interval training, which means you rest twice as long as you work. For example, if you sprint at an all-out intensity for 20 seconds, you'll rest for 40 before sprinting again. This is ideal for cardio intervals including sprints on the treadmill, stationary bike, indoor rowing machine, stair-climbing machine, or an elliptical, because you can ramp up the intensity very quickly.
Keep in mind that this is just a starting point—as you get more advanced, you can start to reduce your resting time, shifting to a 1:1 work to rest ratio. Or, you can try another common HIIT protocol known as Tabata. Here you’ll go all-out for 20 seconds and rest for 10 seconds for a total of eight rounds. This would be a 2:1 ratio, because you're working twice as long as you rest. However, Tabata is supposed to be extremely difficult—you should be giving it everything you've got and still only take 10 seconds in between.
No matter what your ratio is, you should be taking just enough rest that you can do your next interval with all-out intensity, but not so much that it's easy.
Bodyweight cardio—weight-free strength moves done at a speed that gets your heart rate up—can definitely fall under the high-intensity interval training category, but there’s a good reason the work-to-rest ratio is different. What it comes down to is that, as hard as these bodyweight moves might be, you can't accumulate as much fatigue as quickly as you can with cardio-sprint based intervals. Compare sit-ups to [sprints on] a bike: You cannot possibly do sit-ups fast enough or hard enough to match the intensity that you can create on a bike in the same amount of time.
That means, in order to get to the same level of intensity as you’d get doing a HIIT sprint, you have do spend a little more time doing bodyweight cardio. So the circuits tend to be a bit longer—while the rest periods stay roughly the same. For example, it might take 30 seconds to get to a certain heart rate on the treadmill, while to get to the same heart rate doing jumping jacks and squats could take two minutes—the cumulative time spent training is what ramps up the overall intensity of the circuit. Either way you’d want to rest for 60 seconds. Here, we suggest a quick three-minute bodyweight cardio circuit you can do:
Of course, every cardio workout doesn’t need to be interval training. The goal with steady-state cardio is duration over intensity, and it’s a great workout for building up your endurance, whether you’re training to run a race or just want more stamina in the gym.
During a steady-state cardio routine you want to sustain a medium-intensity (about 70 to 80 percent effort) over a longer period of time, say 30 to 60 minutes, or over the course of a distance-based run. So with traditional steady-state cardio your goal should be to break as little as possible. If you're just starting out, it's NBD if you need to take some walking breaks, but as your endurance increases you should aim to take as few as you can.
When you work out at a high intensity, you burn more calories because your heart rate is higher, which is great for fat-loss goals. And if your goal is to build lean muscle mass, minimal rest also trains your body to train more efficiently.
During a workout, give yourself just enough rest so that you can work out at an intense rate for your next interval or set, but not too much rest where you're fully recovered. Not too challenging, not too easy, but just right.