Should I mix intervals and weight training together in the same workout? I go to classes that alternate them.

This question really piggybacks on a question I answered recently (I’ll link to it) about full body and split routine or body part strength training.

The best “after-burn” for exercise occurs after strength training. It’s even better than interval training. After burn is good. That’s like “free” energy expenditure. It’s your metabolism revved up while you’re sitting at your desk or enjoying down time.

You don’t get that when you start mix intervals and weight training.

When You Mix Intervals and Weight Training

You also tend not to get the muscular fatigue which stimulates long term metabolism changes. That in turn stimulates long term body composition changes- in other words fat loss.

If you want greater fat loss you want to spend energy doing the highest quality exercise, not just moving in a frenzy fast. You’ll find a lot of group fitness and bootcamp classes with circuits and people moving rapidly around the room are doing a lot of movement but with less specific purpose.

What's Happening (Pre COVID19, at least)

They’re using battle ropes. And they aren’t even sure what the purpose of that is. It’s going to elevate the heart rate. And it’s going to do it and use the upper body and core in a way not usually included. But do those muscles reach true muscular fatigue to change body composition? Or not?

The same is true of burpees. They’re doing using the whole body. There are about 5 places in a burpee that joints are at risk. Heart rates elevate definitely and fatigue sets in quickly, making those 5 places of potential injury even more risk compared to reward.

Do you know why you're doing each exercise?

What’s the real purpose of a burpee? I'm not sure there is a specific goal with it other than it’s hard and it uses no equipment. It will elevate your heart rate. But check in with your wrists, shoulders, lower back, knees, and blood pressure before you do it. If you don’t have good form doing a squat, a plyometric jump, a plank, and aren’t able to come from lying to standing quickly without dizziness, it’s a no.

Post Production Note

[As a post-production note, I'm reflecting on the idea that certain exercises were once popular, then faded away, and some come back usually in cycles similar to the market and economy. Burpees are one of those moves. If they were safe, effective, free, and everyone should be doing them, why would they have ever disappeared? I don't let it be a secret I'm truly disappointed in trainers who rely on lists of exercise and include burpees regularly among them. I'm of the belief that this approach is not personal training if you can scroll to it in a Facebook feed or find it posted on a whiteboard at a gym. 

If you've been led to believe a personal trainer is layers of a) always dresses in exercise clothes b) has a certification (whatever that means to you since 94% of women don't have a clue about the quality of specific certifications and all assume if trainers are working they're qualified) c) gets excited and cheerleads while other people or they themselves exercise... we have a problem.

In the world we will live in after COVID19 placing higher value on health than ever before, my hope is that we choose with a better filter than that. The stereotypical personal trainer has been created by stereotypical demand by consumers. Its been allowed. It's time to can that and demand better. end post-production note]

Aside from Bootcamps

Now, enough on the types of movements often done in crazy interval training bootcamp sessions, what about hopping on your treadmill or bike for 2 minutes of sprinting between weight training exercises?

It will elevate your heart rate, yes. But is it as valuable or more as splitting your strength – do it well then doing a set of intervals? Do you save time? Do you burn more calories or have an after burn of more energy therefor more fat?

Not necessarily. And if the fast intervals leave you weaker during strength you may do less good during strength. You may be still in “fast” mode and not really reach muscular fatigue as much as get tired.

However, is it detrimental as long as you maintain proper form? If you don’t swing things around or race through as many repetitions as possible (AMRAP)?

How to Decide:

1) Always come back to your goal … your goal… then decide what’s the best protocol based on the best research we have for women just like you to accomplish that goal?

2) You see a lot of variety for variety’s sake …. And if one trainer or instructor is doing it and it’s popular or trending… many will jump on it. If you’ve followed a lot of trends and if your body hasn’t changed positively doing so… there’s a reason.. that’s a gamble. If it wasn’t based on research about you it isn’t as likely to get you results.

We do know… strength training has the greatest after burn.

Intervals have an excellent after burn.

Combining them though doesn’t make it even better. It washes out the value of either.

3) All the above said, if you need a lot of variety to continue to be excited about exercise, then you may want to have this in your routine regularly, say once a week.

Mentioned in the podcast: 

Full Body vs Split Routine workouts