When it comes to getting fit, there are a couple of important terms to understand to help you reach your optimum workout. Check out these two fitness terms and learn what they mean.

The Pump

Immediately following a weight training exercise the muscle may seem full and tight for 15 to 30 minutes. The muscular pump is caused by trapped plasma within the muscle. During muscular contraction the contractile elements exert a force inward upon itself; the muscle diameter increases as it shortens. During intense muscular contraction this force inward occludes the vasculature momentarily backing up blood flow through that particular muscle group. A compensatory increase of blood pressure forces plasma from the congested capillaries into the interstitial spaces of the muscle cells.

Bodybuilders commonly perform pumping up exercises before appearing on stage. For most of us there is no real benefit from achieving a pump except for boosting your ego. Although, inability to achieve a pump is one symptom of overtraining. Fluid volume in the muscle and possibly blood volume decrease when glycogen stores are low. Intense cycling or swimming can also bring about a pump.

The Burn

The burning sensation during certain weight training exercises or high repetition training is caused by an accumulation of acid in the fatiguing muscle. Anaerobic glycolysis utilizes carbohydrates and produces water and acid, or free hydrogen ions. This acid does not clear sufficiently if blood flow is impeded. The vasculature within the muscle is temporarily occluded by the surrounding muscle when it is contracted intensely for a relatively prolonged duration.

The excessive acid acts upon nerve receptors producing the localized burning sensation. Excessive acid accumulation also impedes muscular contraction. Acid interacts with calcium rendering it unavailable for muscular contraction. If repeated regularly, the muscle will begin to adapt to this stress to become more efficient for later bouts.

Many basic or compound exercises (eg. squat, bench press, etc.) have a relatively dynamic contraction allowing the muscle to momentarily relax between repetitions. This can be accomplished by:

• natural transfer of resistance through the bone during complete contraction (eg. lock out on squat, bench press, etc.)
  
• shifting the resistance to synergistic muscle group (bench press: Front Deltoid to Pectoralis Major to Triceps)

In contrast, auxiliary or isolated exercises (eg. leg extensions, lever fly) have a relatively static contraction requiring the muscle to sustain contraction through the majority of the exercise.

Judging the effectiveness of an exercise on the burning sensation is fallacious. The burning sensation has nothing to do with fat burning as popularly believed.

Although the burning sensation may be indicative of the effectiveness of the exercise as it pertains to a specific type of muscular endurance, it does not efficiently promote strength, power, or muscle development. It actuality, an exercise that does not induce the burning sensation as readily may be superior for the development of strength and possibly muscular size.

For example, leg press (basic and compound) is noted to be superior to leg extension (auxiliary and isolated) for both strength and muscular size. It is possible though to supplement strength exercises with muscular endurance exercises to later transfer muscular endurance to muscular strength.

It can also be misleading to judge the exercise's effectiveness on particular muscle group based upon localized muscular fatigue. Often times, beginners feel muscular fatigue in unusual places until they become accustomed to that exercise. The weak link analogy can be attributed to this phenomenon. More common is the misconception that leg raises exercise the lower abdominal.