Optimizing Collateral Damage

The collateral vascular damage inflicted by weight training occurs regardless of one’s specific intentions and to varying degrees based on training intensity, duration, frequency, and volume. Fortunately, it is possible to optimize the benefits of this damage by knowing its specific causes and effects.

Muscle Tissue & Collateral Circulation

Let’s begin by discussing the anatomical location where this exercise-induced damage occurs. The collateral circulation perfuses the intramuscular areas in the form of microscopic capillaries and veinuels. These small and fragile capillaries transport oxygen and nutrient rich blood from the main arteries to the muscles, while the equally small and fragile veinuels work with the lymphatic system to carry expelled muscle tissue wastes and oxygen deficient blood back to the main vascular tree. These small vessels facilitate the exchange of nutrients and oxygen on a cellular level.

This collateral vascular tissue is quite delicate and branches extensively throughout the muscular areas. There is no doubt that the greater the volume of these intramuscular vessels the greater the health of the surrounding lean tissue. In fact, any body tissue cell that is sufficiently supplied with nutrient rich blood by means of collateral circulation has the benefit of the full benefit of the cardiorespiratory system, performing more optimally and living longer than those not readily perfused by collateral blood vessels.

Adipose Tissue

There is also, of course, collateral circulation in other body tissue such as adipose and organ tissue. It is thought by some researchers that the greater the volume of collateral blood provision to fatty tissue, the greater the conversion and storage of circulating calories (mostly over-abundant glucose, triglycerides, and fatty acids). This is obviously undesirable when it comes to weight maintenance and general health.

Causing Collateral Damage

Capillary damage occurs when resistance exercise calls on the target muscle to maintain a sustained contraction for prolonged periods. The longer the duration and the greater the intensity of the sustained contraction, the greater the capillary damage. The greater the volume of high rep sets performed, the greater the damage, as well.

During prolonged contraction, the girth of the working tissue increases enough to ‘pinch’ or block the flow of blood to the working muscles much like the act of pinching a garden hose. With this ‘pinching’ comes a back-up of pressurized blood not able to enter the working intramuscular region. Upon relaxation the blood quickly perfuses into the now relaxed musculature. This pressurized perfusion results in the bursting of already very fragile microscopic capillaries causing an ‘escape’ of blood in and around the working muscles. The extent of the damage will be based on the variables of duration, intensity and most importantly, volume.

The repeated performance of high rep sets back to back (volume training) clearly amplifies the rock hard pump that is the hallmark of volume/high rep training. This so-called ‘pump’ occurs due to the collateral veins’ and the lymphatic system’s inability to capture and then return this exercise induced increase in escaped intramuscular fluid back to the main vascular tree.

Not only are wastes removed slower during a pump, but cellular nutrient and oxygen provision is adversely effected as well. In short, fluids remain in the intramuscular areas for longer periods when experiencing the pumped sensation.

Since nutrient provision and waste removal are both limited during this pump, it becomes directly prohibitive to size and strength training if performed exclusively. Many resistance trainees with scarce body fat covering a particular working muscle during high rep/volume training can see burst capillaries beneath the fascial layer appearing in the form of bruising.

One can consider the vessel damage to require a fairly long recovery period, about the same as that of muscle tissue. Not unlike muscle tissue damage sustained during training, protein is needed to repair these tiny vessels which are they themselves muscle tissue as well. And, not unlike muscle tissue growth during recovery, when these small vessels are repaired, they in turn form new branches. This is the cardiovascular tissue’s way of preparing itself for next exercise session and it leads to a slight increase in muscle size. This usually is caused mainly by the temporary increase in fluid remaining in the musculature just trained.

While the above would give one reason to think the ‘pump’ is something best avoided, it is important to realize that these vessels will recover fully. What’s more, the newly formed branches act to improve and make more efficient the movement of blood in the intramuscular regions. This increased proficiency will also facilitate greater muscle growth in the long run as well. The effected muscle tissue becomes more efficient which is the ground-work for defining better health for all exercise participants young and old, male or female regardless of individual goals.

The burning sensation associated with the ‘pump’ is unmistakable and is the universal indicator of capillary extension. The above information can be thought of an argument in favor of phase training, holistic training, periodization, etc. All people who use resistance training, from retired executives to competitive bodybuilders, require a regular dose of high-rep training to enhance the exchange of nutrients and wastes on a cellular level.

For weight training enthusiast looking for size and strength increase, consider employing some high-rep training occasionally to optimize energy provision and improve cellular performance.


These resources are for the purpose of personal trainer growth and development through Continuing Education which advances the knowledge of fitness professionals. This article is written for NFPT Certified Personal Trainers to receive Continuing Education Credit (CEC). Please contact NFPT at 800.729.6378 or [email protected] with questions or for more information.
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