Don't do Cardio before Lifting Weights: Research Review

Have you ever wondered if it's a good idea to do cardio and weight training on the same day? Does one affect the other and if so, what's the best order to do your exercise in. We'll look at what some of the scientific research says in this "Research Review".

I love the idea of people understanding the science of health, nutrition and fitness a little better. I’m a scientist at heart and I’ve also spent 5 years of my life working as a teacher so making difficult concepts a little more understandable and accessible is something I really enjoy.

I decided that I want to start an ongoing series of articles on the blog that will focus on one research paper at a time, breaking down the research and (hopefully) making it a little easier to understand. I’d also like to add my own critique and opinion on how the research is relevant to the everyday person trying to improve their diet, fitness and health in general.

The first research paper I’m going to review is all about the effects that aerobic exercise can have on your weight training progress if you do your cardio immediately before lifting heavy things. When I recommend an exercise routine to my clients I frequently get asked if they can do cardio on the same day as their strength training. This article will go through some of the reasons why I don’t usually recommend it.    

Many people who exercise to get fitter and healthy will often do a combination of aerobic exercise (cardio) such as running, cycling, swimming etc. and strength training such as weight lifting. At the risk of oversimplifying things, lifting weights allows you to build strength and muscle (which looks good) while cardio is often used to burn extra calories and reduce body fat.

Most good coaches will probably agree that a combination of strength training and cardio will help people achieve the best results when it comes to looking better and being healthier, in general. However, how you combine these two very different types of exercise can affect the results you get longterm. For example, what happens when you decide to do your lift weights right after going for a run? Let’s have a look at todays study to find out.

In this study, 11 healthy men who trained regularly with weights (between 2 and 4 days a week), did a resistance exercise session 10 minutes after doing one of 4 different aerobic exercise routines. Each volunteer did each of the aerobic routines with at least 72 hours of rest in between.

The 4 different aerobic exercise (AE) routines included:

1. Running at a moderate intensity for 45 minutes
2. Running at a moderate intensity for 20 minutes
3. Running at a high-intensity intervals for a total of 15 minutes with a total of 15 minutes of low intensity running in between
4. Running at moderately high intensity, uphill for 20 minutes

The resistance exercise (RE) routine included the following multi-joint exercises:

• High Pull
• Squat
• Bench Press
• Deadlift
• Push Press

These exercises were performed in the order listed for 3 sets each of about 10 reps (except for the high pull, which was done for 6 reps), with 3 minutes rest between sets; so it was pretty standard weight training session.

The control for the experiment (which gives the scientists values for comparison) was a light warm-up of 5 minutes of treadmill walking, some light stretching and some light warm-up sets of the RE movements, instead of cardio. 

During each RE routines performed after each of the different AE routines, the researchers measured:

• Number of reps performed for each exercise
• Bar speed
• Power
• Heart Rate
• Blood lactate (a measure of metabolic exertion)
• Relative Perceived Exertion (RPE) (a measure of how hard the volunteers found the exercises)

Basically, they found that doing cardio 10 minutes before lifting weights means you’ll perform worse in the gym.

In general, all of the different AE routines ended up in:

• less repetitions done
• less power and
• lower bar speed

...for all the different gym exercises. Routine 1 (running for 45 minutes) and especially routine 3 (the high-intensity interval training) had the greatest effects on reducing gym performance. Of all the exercises, squats were the exercise that was most affected by doing cardio.

The table below shows the number of reps performed for each resistance exercise after each of the AE routines (1-4). The column on the left is the control group, for comparison and shows that all AE routines ended up in less reps done (or at least with a tendency for less reps).

On top of less reps, less power and less bar speed, cardio before weights also resulted in higher levels of blood lactate (a by-product of muscular exertion) and relative perceived exertion, meaning the volunteers felt they were working harder after the cardio.

This was a pretty well done experiment in my opinion, for a few reasons:

Pros:

• The volunteers were already used to resistance exercise so the results apply to people who train regularly
• The volunteers were well instructed in the movements with a few training sessions before the actual experiments, which were also used to determine the AE training intensities
• Each volunteer performed each of the AE routines and had plenty of time to recover (72 hours) between each experiment
• The experiment used multiple multi-joint (compound) exercises which gives a wider picture of how different exercises are affected by cardio

Cons:

• There were only 11 volunteers which means it’s hard to extrapolate the results to the general population
• All the volunteers were men which means the same results “might” not apply to women  
• The weight training was performed only 10 minutes after the cardio so we can't be sure if the volunteers would have done better if they had more time to recover

As I mentioned earlier, most people perform a combination of cardio and resistance exercise to reach their fitness and weight-loss goals. With my own clients, I prefer to focus on weight training to help them build muscle and strength which helps them to develop healthier and (debatably) more attractive bodies in the long term. I do recommend cardio but more as a supplement to the weight training, which I feel gives better results.

Considering I feel that weight training gives better results, it makes sense to try and get the most out of your weight training routine. In that case, doing cardio before lifting weights doesn’t seem like a good idea. In general, the more volume you can do when weight training, the better. The volume of any weight training exercise is basically the weight you lift multiplied by the number of reps multiplied by the number of sets. Volume is directly related to muscle growth and subsequent strength development so the more volume you can do and recover from, the better.

This study basically shows that doing cardio before lifting weights not only reduces the amount of reps you can lift (which reduces volume) but also reduces power and bar speed which are important for strength and power athletes.

It’s also important to note that squats were the exercise that was most negatively affected by doing cardio. This isn’t really surprising considering all the AE routines were different variations of running, which obviously would tire out the legs. On top of that, the longer and more intense running routines (45 minutes of running and the high-intensity interval running) resulted in the worst gym performance.

That depends (my favourite phrase) on your own goals and the time you have available to train. If your goal is to get bigger and stronger in the gym (which I feel is a great goal for most men and women, even if they’re not athletes or bodybuilders), then my advice would be to do your weight training BEFORE you do cardio (if you do it at all). This allows you to do more volume and develop more muscle. This would be especially true if you're planning on doing a leg day... running before hand might not be a great idea.

But, if you’re training for a marathon or an iron-man or other endurance event then obviously it’s important to give priority to your cardio and just supplement with weights. Interestingly, the reverse of this experiment has also been shown to be true: doing weights before cardio can also reduce performance during aerobic exercise. Even when weight training is a priority, doing some cardio too will bring it’s own benefits (such as help to control body fat levels) but it’s best left till the end of your session or for a different day.

It also depends on the amount of time you have to dedicate to different exercise. Some people’s schedules force them to do weight training and cardio on the same day or in the same time slot. In that case, you work with what you have but if your goal is developing your muscles to their maximum (which is a good plan) then it’s a good idea to lift those weights before hitting the treadmill or exercise bike.

Train well, folks.

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1. Ratamess NA, Kang J, Porfido TM, Ismaili CP, Selamie SN, Williams BD, Kuper JD, Bush JA, Faigenbaum AD. Acute resistance exercise performance is negatively impacted by prior aerobic endurance exercise. J Stren Cond Res. 2016 Oct 30. (10):2667-2681.    

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