Intensity has been identified as the single most crucial factor to success in your training. Intensity can be defined as the percent of your momentary ability to perform an exercise.

Intensity has nothing to do with how much resistance you are using, nor what percent of your 1 repetition maximum is for a chosen exercise. It refers to the DEGREE OF DIFFICULTY that you experience during the exercise. The specific intensity required to produce optimal gains in strength is unknown at this point. However, if you are a healthy person and perform an exercise to the point of MOMENTARY MUSCULAR FAILURE (100% intensity), you can be assured that you have attained a level of intensity that will stimulate growth and strength (34& 35).

What is "HIT"?

The acronym "HIT" stands for HIGH INTENSITY TRAINING. HIT simply means organizing your workouts so that they are:

1. HARD - as hard as possible IN GOOD FORM.

2. BRIEF - 1-3 sets of a few basic exercises performed in an hour or less.

3. INFREQUENT - No more than three times per week, often times two, or even one.

4. SAFE - HIT is meant to be extremely productive in terms of size/strength gains AND also has a built-in safety component. One of the fundamental goals of strength training is to act as INJURY PREVENTATIVE

HIT is a disciplined style of training which is based on the two universally known factors affecting muscular growth - OVERLOAD and PROGRESSION.

The reps should be done in a controlled fashion so tension is placed on the muscles. Some use a 2 second count for the concentric (lifting) phase while others use a 20 second count. The key is performing QUALITY repetitions to a point of volitional fatigue.

One set IS productive, although some high intensity advocates sometimes choose to perform more than one set. Some people may require additional sets. As a general rule, with of course some exceptions, one set performed in a high intensity manner will provide all the stimulation you need.

ii) General Guidelines to HIT BRIEF, HARD work done INFREQUENTLY (34).

When you're in the gym you want to focus your energies on only performing work that is productive, i.e., growth producing. In good form, you push yourself as far as you can go on every set. Now, by training this way you simply CANNOT do the marathon 2-3 hour workouts the "champs" say they do in the muscle mags.

HIT can be summed up in the following GENERAL guidelines. These guidelines - or ones very similar - have formed the basis of strength training programs for years:

1. TRAIN WITH A HIGH LEVEL OF INTENSITY.

Intensity is defined as "a percentage of momentary ability". In other words, intensity relates to the degree of "inroad" or muscular fatigue, made into muscle at any given instant. Research, going back almost 100 years now to studies done by German scientists, has conclusively shown that intensity is the SINGLE MOST IMPORTANT FACTOR in obtaining results from strength training.

It has been shown that the HARDER that you train (intensity), the GREATER the adaptive response. A high level of intensity is characterized by performing an exercise to the point of concentric (positive) MUSCULAR FAILURE, i.e., you've exhausted your muscles to the extent that the weight cannot be moved for any more repetitions. Failure to reach a desirable level of intensity - or muscular fatigue - will result in little or no gains in functional strength or muscular size as low intensity workouts do very little or nothing in the way of stimulating muscle size/strength. Evidence for this "threshold" is suggested in the literature by the OVERLOAD PRINCIPLE (Enoka, 1988; Fox and Mathews, 1981; Hochschuler, Cotler and Guyer, 1993; Jones, 1988; Wilmore 1982). Essentially this principle states that in order to increase muscular size and strength, a muscle must be stressed - or "overloaded" with a workload that is beyond its present capacity. Your intensity of effort must be great enough to exceed this threshold level so that a sufficient amount of muscular fatigue is produced.

2. FOLLOW THE "DOUBLE PROGRESSION" TECHNIQUE IN REGARDS TO REPETITIONS AND WEIGHT.

For a muscle to increase in size and strength it must be forced to do PROGRESSIVELY HARDER WORK. Your muscles must be overloaded with a workload that is increased steadily and systematically throughout the course of your program. This is often referred to as PROGRESSIVE OVERLOAD.

Therefore every time you work out you should attempt to increase either the weight you use or the repetitions you perform relative to your previous workout. This can be viewed as a "double progressive" technique (resistance and repetitions). Challenging your muscles in this manner will force them to adapt to the imposed demands (or stress).

3. PERFORM 1 TO 3 SETS OF EACH EXERCISE.

In order for a muscle to increase in size/strength it must be fatigued or OVERLOADED in order for an adaptive response to occur. It really doesn't matter whether you fatigue your muscles in one set or several sets - as long as your muscles experience a certain level of exhaustion.

When performing multiple sets, the cumulative effect of each successive set makes deeper inroads into your muscle thereby creating muscular fatigue; when performing a single set to failure, the cumulative effect of each successive repetition makes deeper inroads into your muscle thereby creating muscular fatigue. Numerous research studies have shown that there are NO significant differences when performing either one, two or three sets of an exercise, provided, of course, that one is done with an appropriate level of intensity (i.e. to the point of concentric muscular failure).

4. REACH CONCENTRIC MUSCULAR FAILURE WITHIN A PRESCRIBED NUMBER OF REPETITIONS.

As stated above, research shows that our level of intensity is the most important factor in determining your results from strength training - the HARDER you train, the BETTER your response. As muscle hypertrophy is an adaptive response by the body to stress, you should always strive to go as far as you can go on that "impossible" rep. Every centimeter matters. Your "impossible" rep should last between 10-15 seconds. One could even call this an "isometric rep".

If concentric muscular failure occurs before you reach the lower level of the repetition range, the weight is too heavy and should be reduced for your next workout. If the upper level of the repetition range is exceeded before you experience muscular exhaustion, the weight is too light and should be increased for your next workout by five percent or less.

The GENERAL recommendation is 8-12 repetitions But this can vary from individual to individual, and from body part to body part. In many cases people have been known to benefit from higher reps for their lower body (12-15), while lower reps for the upper body (6-8). The most important thing to remember here is that it the *number* of repetitions isn't the key factor - TIME is. One can perform a set of 10 reps in as low as 10-15 seconds, or a set of only 1 rep in 60 seconds. So how many seconds per repetition? The general guideline is a 6 second repetition consisting of a 2 second lifting (concentric) phase, followed by a 4 second lowering (eccentric) phase. The emphasis is placed on the lowering, or NEGATIVE, as research has shown this to be the most productive part of the rep.

The lowering of the weight should also be emphasized because it makes the exercise more efficient: the same muscles that are used to raise the weight concentrically are also used to lower it eccentrically. The only difference is that when you raise a weight, your muscles are shortening against tension and when you lower a weight, your muscles are lengthening against tension. So, by emphasizing the lowering of the weight, each repetition becomes more efficient and each set becomes more productive. Because a muscle under tension lengthens as you lower it, lowering the weight in a controlled manner also ensures that the exercised muscle is being stretched properly and safely. Thus in a 8-12 rep scheme with the above guidelines, each set should take you between 48-72 seconds until you reach concentric muscular failure.

5. TRAIN FOR NO MORE THAN ONE HOUR PER WORKOUT.

If you are training with a high level of intensity, more than one hour is counterproductive as it increases the probability of overtraining due to a catabolic hormone called cortisol. Overtraining, next to injury, is your worst enemy. Avoid it like the plague. In addition, the faster you can complete your workout, given the same amount of sets performed, the BETTER CONDITIONING obtained.

6. MOVE QUICKLY BETWEEN SETS

The transition time between each set varies with your level of conditioning. You should proceed from one exercise to the next as soon as you catch your breath or feel that you can produce a maximal level of effort. After an initial period of adjustment, you should be able to recover adequately within 1 to 3 minutes. Training with a minimal amount of recovery time between exercises will elicit a metabolic conditioning effect that cannot be approached by traditional multiple set programs.

7. EXERCISE THE MAJOR MUSCLE GROUPS FIRST.

The emphasis of your exercises should be your major muscle groups (i.e. your hips, legs and upper torso). You should select any exercises that you prefer in order to train those body parts. It is recommended that lower body work be done first, as it is more taxing. This is not always the case, as a technique for bringing up a lagging body part is to work it first in your routine, but it is a general outline.

8. DO NOT SPLIT YOUR ROUTINE - DO NOT WORK YOUR BODY ON SUCCESSIVE DAYS

Many bodybuilders practice a split routine. The reasoning is that training their upper body on one day and lower body on the next day allows them additional time to work each muscle group "harder". HIT advocates fervently believe that this is NOT the case.

First, split routines lead you to believe that *more* exercise is better exercise. Remember HARDER exercise is better. And if you train harder you MUST train briefer, not longer. You cannot train hard for a long period of time. Thus, out of physiologic necessity, people who use a split routine have to reduce the intensity of their exercise which leads to less growth stimulation.

9. GET AMPLE REST AFTER EACH TRAINING SESSION

Believe it or not, your muscles DON'T get stronger while you work out. Your muscles get stronger while you RECOVER from your workout. After high intensity training your muscle tissue is broken down (although that's a very basic way of describing it) and the recovery process allows your muscle time to rebuild itself.

10. AS YOU GET STRONGER DECREASE THE FREQUENCY OF WORKOUTS AND/OR AMOUNT OF SETS

Exercise physiologists have found that your strength increases disproportionately to your recovery ability. Thus the stronger you get the LESS high intensity exercise you can tolerate. Some authorities, such as Dr. Ellington Darden, mention a "300/50%" ratio of strength to recovery ability potential. Thus in theory, the average trainee has the potential to increase his untrained strength by a factor of 4, but his recovery ability will only increase by a factor of 1.5.