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Before or After? When to Do Cardio in Your Weights Session

Cardio and Weights: Prioritize Your Workout

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Updated May 20, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Scenario 2 - Cardio before Weights

You get stuck into the cardio first up for 40 minutes because you think you will be too tired to tackle it at the end of the weights program. You understand you will expend more energy with cardio when you're fresh, so you can use more energy overall in the session, which is what you're aiming for.

Fresh legs for better cardio. If you do your cardio before you lift, there’s little doubt you will do this part of your program more efficiently, which probably means at higher intensity and with a higher aerobic fitness outcome. Heavy legs and arms after weights are not conducive to a good cardio session. I’ve tried both sequences many times, and running first is my preference even without the technical considerations.

As explained in So You Want to Burn More Fat, cardio of moderate output expends considerably more energy than an equal session of weights, so if you want to maximize energy output for weight loss and aerobic fitness, doing a solid cardio session is essential. Doing cardio first will maximize your output.

On the other hand, with attention to fueling, refueling and fluid intake, you will still be capable of a strong weights session after your aerobic session.

Strong arteries. It's also important to know that aerobic exercise is important even for specialist weight lifters and bodybuilders from a health perspective. Cardio helps keep the arteries elastic, which is beneficial for cardiovascular health. This is called ‘arterial compliance’ and several studies have shown that this worsens in weight trainers who do little aerobic exercise.

Study Shows Cardio before Weights is Beneficial

A study from the Human Performance Research Center, Brigham Young University, Provo, Utah, examined what happened to ten men who did resistance only, run only, resistance-run, and run-resistance sessions. (‘Resistance-run’ means weights before cardio and vice versa.)

Here’s what they reported:

  1. EPOC, the measure of the afterburn or energy output after you stop exercising was greatest when cardio was done before weight training.
  2. Running after a weights session was physiologically more difficult than doing it before lifting weights. (This has implications for efficiency and possibly safety.)
  3. The researchers recommend “performing aerobic exercise before resistance exercise when combining them into one exercise session”.

This was not a large study, so the results should be interpreted with caution. Nevertheless, this is in line with my own experience with this training sequence, and also that of some clients.

Other research found that 'running economy' is also impaired after a weights session, another reason why the weights-cardio sequence is less efficient.

Score for Scenario 2: the evidence is not quite in yet, but I’ll score it 4 our of 5 for doing cardio before a weights session.

Cardio Killed My Muscle

Some weight trainers are reluctant to do much cardio training because they believe it produces catabolic hormones like cortisol that break down muscle stores for fuel thus interfering with the anabolic muscle building process.

Although this subject is worthy of a more complete article on weight training nutrition and metabolism, a brief response is that you can protect muscle from this process by ensuring adequate nutrition before, during and after a session and by keeping aerobic training to under one hour if you have muscle building goals.

Forty or so minutes of cardio within an adequate nutritional environment is not going to hurt your muscle. In fact, in view of the discussion above, doing cardio after weights could be more damaging to muscle as 'beaten up' muscle strives to deal with the burden of aerobic activity. Your immediate post-weights activity should be dedicated to maximizing the anabolic environment. This is time for building up not breaking down. You achieve this by eating sensibly and adequately and by resting and sleeping -- and by not doing cardio after weights.

Summing Up

Here are my recommendations:

  1. Do most of your aerobic exercise before your weights program if you do both in the same session.
  2. Complete your weights session, cool down then immediately concentrate on recovery, repair and rebuilding rather than additional exercise.
  3. Consider separate sessions for cardio and weights on different days. This is a popular option when weight loss is not the primary goal. You could also experiment with separate sessions on the same day, but you need to get your refueling right with this approach.
  4. If weight loss is a primary goal, doing both on the same day with cardio first may offer some advantages in increased metabolism and energy expenditure.
  5. If strength, rather than hypertrophy (bigger muscles) is a goal, you probably should do cardio and weights on separate days because the heavier lifts may not go as well after doing cardio first. You need to be as fresh as possible for those 4RMs.
  6. You could mix and match upper and lower body workouts. For example, treadmill running and upper body weights one day and lower body weights and swimming another day.
  7. Don't get too hung up on this whole idea; if it suits you to reverse the order occasionally, it won't be a problem.

Sources:

Drummond MJ, Vehrs PR, Schaalje GB, Parcell AC. Aerobic and resistance exercise sequence affects excess postexercise oxygen consumption. J Strength Cond Res. 2005 May;19(2):332-7.

Palmer CD, Sleivert GG. Running economy is impaired following a single bout of resistance exercise. J Sci Med Sport. 2001 Dec;4(4):447-59.

Miyachi M, Kawano H, Sugawara J, Takahashi K, Hayashi K, Yamazaki K, Tabata I, Tanaka H. Unfavorable effects of resistance training on central arterial compliance: a randomized intervention study. Circulation. 2004 Nov 2;110(18):2858-63.

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