Monday, September 23, 2013

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

"Should I do aerobic training before or after a weights session?" This 
is a frequently asked question and one over which a wide spectrum of 
opinion exists even though it may seem like trivia if you're new to 
weight training. Yet, as with many issues in the exercise sciences, 
answers to complex questions can be blurred by qualifications and 
exceptions and tempered by the exercise goals you have set -- weight 
loss, muscle, strength, sporting prowess, appearance and so on. 

The following attempts to clarify the issue and provide some clear 
direction.

Cardio and Aerobics 

Aerobic exercise, often called 'cardio' for short, is any exercise at 
an intensity at which oxygen can be sustainably supplied to large 
muscle groups over time and which places consistent demands on the 
heart and lung system, the cardiorespiratory system. 

Cardio is something you do at a sustained pace over a longer period of 
time rather than in short bursts of energy such as in interval running 
or lifting weights. Cardio is walking, jogging, distance running, 
swimming and cycling; and using treadmill, stepper, cross trainer and 
rowing machines in the gym. Blood glucose and stored glucose and fats 
are the main fuels used in aerobics. 
Training with Weights 

In contrast, lifting weights is an activity practiced in short bursts 
of anaerobic (without oxygen) activity. In effect, 'anaerobic' doesn't 
mean that we stop using oxygen, it just means that the activity is of 
such an intensity that the muscle's requirement for oxygen is 
exceeded, resulting in metabolic products such as lactate and an 
eventual inability to continue at that intensity. Stored muscle 
glucose and phosphocreatine are the main fuels used in strength 
training. 

Now that you're clear on the essential difference between aerobics and 
weight training, let's consider this in the context of doing cardio 
before or after a weights session. I'll assume that a 'session' is one 
visit to a gym for the purposes of a workout. Let's examine the 
scenarios I propose.

Scenario 1 - Cardio after Weights 

You walk into the gym and do a warmup on the treadmill for 10 minutes, 
but you don't want to do too much cardio because you reckon you need 
the energy to max out your weights session. Anyway, you heard that 
you'll burn more fat if you do it after the weights. 

Saves energy for weight lifting. This may seem to be good logic; 
however, doing 40 minutes of cardio at moderate pace is not going to 
deplete enough energy to prevent you from lifting well. As long as 
you've replaced your carbohydrate glucose stores after any previous 
exercise session with proper eating, the body will have stored up to 
500 grams, or a pound of glycogen. 

A jogging or running treadmill session of 40 minutes may use about 600 
kcalories of energy, depending on your size and pace. Of this, some 
fuel will be fat, some will be stored glucose and some blood glucose. 
A reasonable estimate is that you would use around 80 to 100 grams (3 
or 4 ounces) of stored glucose out of, say, 400 grams that you have 
available. You can see that you have plenty left in reserve for 
strength training. 

What's more, if you replace some of this used fuel with a sports drink 
or energy bar before you start the weights, you'll only be a little 
depleted from when you walked in the door. 

Burn more fat. Now this one really sounds attractive, the idea being 
that if you deplete some carbohydrate stores, particularly blood 
glucose, with an initial weights session, you'll be in fat burning 
mode. Theoretically this makes some sense but as we saw in my article, 
So You Want to Burn More Fat1, the fat burning zone is a mythical 
construct and what really matters is how much energy you expend 
overall. 

Score for Scenario 1: sounds good, but in reality only 2 points out of 
5.

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. 


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Larry Austin
www.PaladinFitness.com


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