I have been bodybuilding for 3 years but never really knew when to place my cardio activity. I work out four days a week. Currently I do around 40 minutes on a bike during my rest days (3 per week). Is this a proper routine or will it have an effect on my muscle mass?

Also, if I do four sets of a certain exercise should I augment the weight charge after each set or is this improper? I've heard different versions.

There really aren’t any specific research studies that have been done on the subject of the duration, frequency, and intensity of cardiovascular exercise as it relates to the simultaneous lifting of weights and the subsequent development or maintenance of muscle mass. However, there is plenty of empirical data that I have seen and experienced throughout my career so that I can give you a quality response.

The upper limit for duration of aerobic exercise without sacrificing muscle mass is right at 30 minutes. Most people who are focusing on gaining mass, but still want to keep their body fat levels under control, will not go more than 20 minutes in duration. The weekly frequency of this aerobic training should not be more than 5 days per week as well. You mentioned that you do cardio for 40 minutes and only 3 times per week. I still feel it is better to not go more than 30 minutes even though your frequency is less!

Let me say another key point here. The intensity at which the aerobic training is done is also of paramount importance. Keep your heart rate at OR BELOW 70% of your age predicted max heart rate (APMHR). You can read more about finding this heart rate if you type in "aerobic guidelines" in the search function on the home page of Fitrex.com.

To further answer your question, if your goal is to gain (or at least maintain) lean body mass than you should do your aerobic exercise at least 4 hours before your weight training session OR any time after. Say you train with weights over your lunch hour or after work, you would be fine doing your aerobic training when you get up in the morning because you would have at least 4 hours of rest before doing your weight training workout.

Also, because I am recommending the intensity of your aerobic session be kept low (70% APMHR), doing it after your lifting session will not have any negative consequences concerning hormonal responses (growth hormone, testosterone and cortisol levels) and ultimately, physical recovery.

To summarize, don't go more than 20-30 minutes in duration, keep your frequency at 3-5 days per week, keep your heart rate at the relatively low intensity range of 70% (or below) of your APMHR, and make sure you do your cardio either 4 hours before you weight workouts or anytime after! If you do this you will not lose any of your hard gained muscle mass and you will maximize the loss of bodyfat!

Now, answering your next question can be much more involved that you might think. There are times when you do not need to change the weight (increase) after each set. But, there are times when you should! It all depends on the type of exercise you are doing, your particular goals, whether you have warmed up or not, how many repetitions you are doing and your individual strength levels and technical proficiency skills. Whew, see what I mean!

Let me give you a couple specific examples. If you are doing a single joint exercise like leg extensions, and you are in one of the first phases of training where your repetitions are a little higher, say 10 or so, you will be fine doing 4 sets of 10 reps with the same weight. However, if you are doing a multi-joint exercise like the squat, you will obviously have to increase the weight as you go through the first couple of warmup sets. Then, you may have to change the weight after each of your actual "work" sets. And, you may have to increase or decrease the weights depending on how the workout is set up. Get on one of my programs and jump around between the weeks of training to see what I am talking about!