Capillary Density and Muscular Growth

Capillary Density

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If you're like most bodybuilders, anything that will boost your gains in the gym is always welcome. Drug free or not, a greater understanding of capillary density and its implications on muscular growth may well prove to be a fantastic boost to how much muscle you can add to your body and how quickly you can achieve that growth.

The Role Of ATP In Anaerobic Training

Anaerobic training is a process whereby the ATP (adenosine triphosphate) used for exercise is derived in the absence of oxygen. Note: The energy in food is broken down and delivered through the energy-rich compound (ATP). When ATP combines with water in a process called hydrolysis and is acted on by a special enzyme called adenosine triphosphatase the ATP bonds are broken down to form adenosine diphosphate or ADR The chemical breakdown results in the release of free energy. (Fitness: The Complete Guide, Hatfield 1996: 52)


The amount of ATP stored in the body (about 85 g or 3 oz) is only enough energy to perform maximum exercise for several seconds. Because ATP can't be supplied by way of the blood or other tissues it must be recycled continuously within each cell. Some of this energy for ATP resynthesis is supplied rapidly and without oxygen by the transfer of chemical energy from another high-energy compound called creatine phosphate or CP. The cell's concentration of CP is about three to five times that of ATP. For this reason CP is considered the high-energy phosphate reservoir. If the activity is short-lived CP is usually readily available to be broken down in the ATP reformulation process. (Fitness: The Complete Guide, Hatfield 1996: 52) In essence, the way the body produces ATP varies with different intensities and duration. This process determines whether training is anaerobic or aerobic.

Weight Training And Hypertrophy


While hypertrophy (and possibly hyperplasia) is a welcomed physiological adaptation, some adaptations may hamper the growth process. As we increase lean muscle mass, capillary density decreases. If that doesn't sound an alarm in your mind then let me explain.

The Circulatory System Dissected

The human circulatory system is a closed loop that circulates blood to all body tissues. Circulation of blood requires the action of a muscular pump the heart that creates the pressure head needed to move blood through the system. Blood travels away from the heart in arteries and returns by way of veins.

The system is considered closed because arteries and veins are continuous through smaller vessels. Arteries branch extensively to form a tree of smaller vessels. As the vessels become microscopic they form arterioles, which eventually develop into beds of smaller vessels called capillaries.

Capillaries are the smallest and most numerous of all blood vessels; all exchanges of oxygen, carbon dioxide and nutrients between the tissues and the circulatory system occur across capillary beds. The number of capillaries decreases as lean muscle mass increases. The opposite outcome is true with aerobic exercise, where capillary density increases as part of the adaptation process. (Exercise Physiology, Powers and Howley 1990: 190-192)

A decrease in the number of capillaries could potentially slow the growth process down. Imagine if you were trying to grow a tree from sapling to cedar. As the live got larger, you decreased the water, oxygen and nutrient supply. Naturally, as you'd expect, growth would begin to slow down and a point would be reached where the tree would not receive enough nutrients, oxygen and water to grow any more. Decreasing capillary density in proportion to increasing lean mass may present the same problem. This decrease leads to the need or potential need for an aerobic component to be added to a mass-building program.

Different Schools Of Thought

A couple of different schools of thought exist on the role of aerobic training in bodybuilding that have potential applications. The problem is these schools of thought are on opposite ends of the continuum. Let's see how we can use these two opposing views to our advantage.

On one end of the continuum you have no aerobics while mass building. Mike Mentzer believed that we only have a certain number of adaptive/recovery units available to deal with stress that are not set aside for different types of stress anaerobic training, aerobic training, injuries etc. His contention was, if the goal is to build lean mass all our adaptive energies need to be focused on that process. Incorporating an additional stressor, like aerobic training, would be out of the question with this philosophy.

The other end of the continuum is the belief that the more cardio you do the better because you can consume more calories in an attempt to stimulate or support growth without getting fat and you build up cardio-vascular density, which is among other things, increasing the number of capillaries and/or capillary density. This philosophy has been popularized by John Parrillo.

As you can see, we have a valid need for the addition of an aerobic component to our bodybuilding program. The question is how do we meet this need? After all. two of the great minds of bodybuilding are miles apart on their philosophies.

Specificity And Overload Principles

The principle of specificity states that muscle fibers involved in training will respond specifically according to the type of training. For our purposes, this theory means we need to focus on an aerobic training stimulus.

Since we are interested in studying all muscle groups, specific exercises and exercise protocols need to be applied to every muscle group. In essence, we won't be using the bike, stair climber or treadmill as the focus of our aerobic component. (Remember, this aerobic component is being used to bolster the process of attaining new lean muscle mass not to be confused with calorie burning.)

The principle of overload states that for a process of adaptation to be stimulated, a greater than normal intensity, duration or frequency of exercise must be present. This theory is the same principle we use in stimulating lean mass gains.

Applying the aforementioned principles must also be done without overtraining, that is exceeding our body's ability to recover, by placing too great a demand on it. You can overtrain by applying too great an overload or not allowing enough lime to elapse between training sessions for the demand to be met. Other factors, such as diet, stress (any form) and drugs, can also affect overtraining. Even though, John Parrillo and the late Mike Mentzer are not close in what they advocate, a hybrid of the two philosophies may be the answer.

According to the principle of specificity, we need to target the specific muscle group with specific training to create the stimulus for our desired outcome. That specific training has to be strictly regulated in terms of volume and frequency, as to not constitute overtraining, and to be as efficient as possible. This principle may require some adjustments to your present training scheme. Let's take a look at some basic frameworks, which may be just the compromise we need.

Combining It All Together

The whole body can be worked with three exercises (or similar) pushups, deadlifts and squats. Here is how they can be used to help build capillary density. These exercises are to be spread throughout an entire training schedule, evenly spaced to maximize recovery. You will work all the muscle groups of the body, while using the least number of exercises possible.

Using exercises that require balance and stabilization are of much greater benefit to the bodybuilder than strictly using machines, the human body was designed for labor.

Muscles were intended to be used in concert, the pushup, deadlift and squat meet these design specifications.

The 20 to 25 rep range is the choice for stimulating an increase in cardiovascular density. Doing only 12 to 15 reps is too much of an intermediate level ol repetitions between anaerobic and aerobic training and we need to be concerned about hampering strength gains. Doing 20 to 25 reps offers a host of awesome benefits - possible release of growth hormone, increased use of fatty acids for fuel and a Hushing of your musculature pumping fresh blood and nutrients in and wastes out.

In addition to the least number of exercises possible to obtain our end goal, the least amount of work per exercise is also warranted a single set. In this case, we are talking about a total of 1 set. You will already be sufficiently warmed up from your workout. Since this set will be the final exercise of the day, a warmup will not be necessary. Besides, you will be warming up for 20 or so reps before the last few struggling reps preceding failure.

To summarize: do 1 set of pushups, deadlifts and squats to all-out failure in the 20 to 25 rep range - one exercise per workout when possible and spread them out as evenly as possible. For example, deadlifts following back on Monday; pushups following chest on Wednesday; squats following legs on Friday. Again, you may have to make some adjustments to accommodate, but it will be well worth the effort.

You can achieve the benefits of both worlds. It's just a matter of manipulating the various theories to maximize growth. By upping your rep range on anaerobic-type exercises you'll get the advantages of aerobic training. You will also increase your capillary density and achieve the overall development that you've been looking for.





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