One of the biggest controversies in bodybuilding is whether cardio should be performed before a workout vs after a workout. There are experts and professionals who come down on either side of this comparison so it is important for each lifter to decide for themselves. Many believe that cardio after a workout offers more benefits but there is no universal agreement in the industry on this question. Each method will offer some benefits but may also include some drawbacks.

Cardio Benefits Before a Workout

Doing cardio before a workout is one option that has a few benefits. Maximum calorie burning is seen and this means that more fat will be burned off. This choice can also increase the Afterburn that is experienced. Cardio warms up the muscle tissues so they may be more flexible during the workout and will not injure as quickly.

Calories Burned are Maximized:

Cardio boosts your metabolic rate for many hours after this activity is stopped, and this will increase the number of calories that are burned off during a workout. When cardio is performed after the workout this metabolic boost is not in effect during the weight training. Cardio before a workout will help burn off a larger number of calories and this is often a reason used to support this method.

Afterburn is Increased:

Post exercise oxygen consumption shows the specific calorie burning that happens after a workout, and this is higher when cardio is performed before strength training. The best afterburn is seen when high intensity cardio is followed by weightlifting. This does leave less energy for the strength training component though, and it may increase the risk of injury from fatigue as well.

Muscle Tissues are Warmer During a Workout:

When cardio starts off any workout session then the muscle tissues have time to warm up completely and may be more flexible and limber. This may mean fewer large tears or other tissue damage that can happen when strength training is started with cold muscles.

Cardio Benefits After a Workout

The benefits of cardio after the workout are numerous. This method allows you to reserve your energy for the weightlifting and strength training regimen because glycogen stores are not depleted beforehand, and it typically provides better hormone profiles and blood PH levels when you reach the cardio component. Better muscle growth, lower injury risks,, and workouts that feel easier are other benefits when cardio happens after a workout.

No Glycogen Store Depletion:

When cardio is performed before a workout this activity depletes the glycogen stores in the body, leaving you tapped out in this area when you start the weightlifting component of the schedule. This can leave you tired, and you may end up cutting the session short as a result. Glycogen stores may help you keep going during the roughest part of the workout and if they are missing you are missing out on the potential benefits the session may cause.

Reserve Energy for Training:

It just makes sense to reserve your energy before strength training instead of using it for cardio. If you perform cardio first then you will be tired and will not have as much energy when you hit the weights. You will not reach the same intensity level because of your fatigue and it will be harder and take longer for you to get ripped.

Better Blood PH Levels and Hormone Profiles:

Cardio causes acidic changes in the blood due to the breakdown of stored energy in the body, and lactic acid can build up quickly when you engage in cardio activity. An acidic blood PH also causes fatigue in the muscle tissues and will cause poor performance as a result. Muscle contraction becomes more difficult and the mass and strength gained will be minimized. Cardio after a workout also means more favorable changes in hormone levels. Cardio activity produces cortisol, a hormone that provides energy by breaking down your muscle tissues, without also releasing the testosterone needed to build up the muscle tissues at the same time. A workout with weight training will release testosterone into the blood, and this protects muscles from being broken down excessively when cardio is performed afterward.

Better Muscle Growth:

The hormone and PH changes that happen when cardio is performed after a workout will provide better muscle growth and faster results. Pathways for building muscle in the body called mTOR pathways will be inhibited after cardio and this affects the growth and size that you can get from your training session.

Lower Injury Risk:

Mental and physical fatigue will increase your injury risks. When your mind is tired or your muscles are exhausted you are more likely to overtrain or to go too far, and you could end up with serious injuries that impact your training schedule and goals. Cardio first means that you are already tired after a grueling session before you ever lift the first weight.

Workouts Feel Easier:

Cardio after your workout will make your training session feel easier because you are well rested before you engage in strength training. After a cardio session you may feel worn out and the workout may seem much more difficult as a result of this. Weightlifting is hard enough as it is, why make it even more difficult?

Cardio Before vs. After Wrokout

For many cardio before a workout vs cardio after a workout is not a difficult decision. A majority prefer their cardio after the heavy lifting is done, but there are those who still believe that cardio before a strength training session works best for them.

Source

http://www.bodybuilding.com/fun/topicoftheweek34.htm

http://www.builtlean.com/2011/11/07/cardio-before-or-after-weights/