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Concentric failure: the momentary inability to lift a weight through the full range of motion

Isometric failure: the inability to hold the weight without movement

Eccentric failure: the inability to lower the weight under control

Concentric failure will occur before isometric failure which will occur before eccentric
failure. On a calorically restricted diet, going past the point of positive failure is probably not a
good idea and will most likely induce overtraining. Therefore, we will only consider positive failure
in the exercise routines.
There is a great deal of debate both in research and popular literature about training to
muscular failure. Some authors feel that training to muscular failure is the ONLY way to
generate adaptations to strength training while others argue that failure is not a prerequisite. A
full discussion of both sides is beyond the scope of this book. This author feels that as long as
individuals are training within a repetition or two of failure (such that at least 10 repetitions are
performed when 12 could have been done in good form) progress should occur.

Repetition (rep or reps)

One repetition of an exercise is the combination of a concentric muscle action and an
eccentric muscle action (a lifting followed by a lowering). Some individuals will perform eccentric
only training (where the weight is lifted by a partner and lowered by the trainee) in which case one
lowering would count as a repetition.

Repetition Maximum (RM)

RM refers to a weight that can be performed X reps but not X+1 reps in perfect form. For
example, if a trainee can do 8 reps in perfect form with 100 lbs but not 9, 100 lbs would be their
8RM weight. The relationship between RM loads and percentage of 1 repetition maximum (the
amount you can lift for 1 rep and 1 rep only) appears in figure 1.

Figure 1: Relationship between reps and percentage of 1 rep maximum

20%

% of 40%

M 50%

A 60%

X 70%

I 80%

M 85%

U 90%

M 100%

100+ 50 20 15 10 8 6 4 2 1

Number of Repetitions

Note: This is a generalized curve and may vary for different bodyparts, individuals and

between men and women.