Bodybuilding and Aerobic Endurance

There are two fundamentally different kinds of endurance: muscular and cardiovascular.

• Muscular endurance is the ability of the muscle to contract over and over during exercise and to recruit the maximum number of fibers to perform that exercise. For example, while doing heavy squats, you fatigue muscle fibers in the leg so quickly that if you want to get through an entire set you need muscle fibers that recuperate quickly and you need to be able to bring many additional fibers into play during the course of the set.
• Cardiovascular endurance is the ability of the heart, lungs and circulatory system to deliver oxygen to the muscles to fuel further exercise and to carry away waste products (lactic acid).

While these two aspects of endurance are distinct, they are also connected. After all, what good is having a well-developed cardiovascular capacity if the muscles you are using in some effort can't keep up the pace and give out? And how well can you perform if your muscles have tremendous endurance ability but your circulatory system can't deliver the oxygen they need?

Just about everyone understands that you increase cardiovascular capacity by doing high volumes of aerobic exercise - exercise that makes you breathe hard, causes your heart to race, and that you can keep up for long periods of time. When you do this you:

• increase the ability of your lungs to take oxygen from the air and transfer it to the bloodstream;
• increase the capacity of your heart to pump large volumes of blood through the circulatory system and to the muscles;
• increase the number and size of the capillaries that bring blood to specific muscles;
• increase the capacity of the cardiovascular system to flush lactic acid (which causes the feeling of burning in the muscles during intense exercise) out of the muscles.

You increase muscular endurance by performing a relatively high volume of muscular contractions. When you do this you:

• increase the size and number of capillaries to the specific muscles being exercised;
• increase the ability of the muscles to store glycogen (carbohydrate), which is needed to create energy for muscular contractions;
• increase the mass of the muscle mitochondria (energy factories) that create substances like ATP (Adenosine Triphosphate) out of glycogen which are used to fuel muscular contraction;
• increase the development of the type of muscle fiber mostly involved in endurance exercise.

There are basically two types of muscle fiber (as well as a lot of intermediate, in-between fiber types):

1. White, fast-twitch fiber is a anaerobic power fiber that contracts very hard for short periods but has little endurance and a relatively long recovery period.
2. Red, slow-twitch fiber is 20% smaller than fast-twitch and not as powerful, but is aerobic and can continue to contract for long periods as long as sufficient oxygen is available.

Because bodybuilding training relies on a higher volume (sets and reps) of effort than weightlifting, it has some cardiovascular benefit and also leads to an increase in muscular endurance. Bodybuilders tend to train at a pace which is just below the threshold of cardiovascular failure - that is, they train as fast as they can without overwhelming the ability of the body to provide oxygen to the muscles. This doesn't make them automatically good t endurance activities, such as running or riding a bicycle, but it keeps them in pretty good cardiovascular shape. When it comes to those other types of activity, you are dealing with both specificity of training and specificity of physical adaption. You have to train on a bicycle to be good on one. You have to work at running to improve your ability as a runner. However, a well-trained bodybuilder will usually be in good enough shape to do well at these kinds of exercises and to show considerable improvement very rapidly, providing his size and bodyweight are not too much of a negative factor.

Arnold Schwarzenegger always believed that cardiovascular endurance is almost as important to a bodybuilder as muscular endurance. Hard training results in a build up of lactic acid in the muscles being used - a waste product of the process that produces the energy for muscular contraction. If the heart, lungs and circulatory system have been able to provide enough oxygen to the area, the lactic acid will be reprocessed by the body into a new source of energy; if not, the buildup will eventually prevent further contraction, leading to total muscular failure.

In my previous blog, I have described the virtues of jumping rope as an excellent cardiovascular exercise that can be performed for both aerobic and anaerobic endurance purposes. Together with my daily cycling and walking, 2-3 sessions a week provide all the cardio training I require. However, some people may find the jump-rope does not suit them or causes them to have problems with their legs and ankles, so other methods of developing cardiovascular conditioning includes treadmills, steppers and rowers.

The fact is, the better conditioned your heart, lungs and circulatory system, the more intense training you will be able to do in the gym and the more progress you will make as a bodybuilder.