Concentric and eccentric phases
. A rep has two phases, i.e., the positive or concentric (pushing or pulling)
part when the muscle shortens, and the negative or eccentric (lowering) part
when the muscle lengthens. Sitting down to a chair is the negative or eccen-
tric phase of a squat, while standing up is the positive or concentric phase.Sets
. An exercise is usually done for multiple sets before moving onto the next
exercise. Sets come in two basic types: warmup sets and work sets. Warmup
sets are done with weights lighter than those to be used for work sets.
Warmup sets prepare you for work sets.Flexion and extension of joints
. Bringing together the bones associated with a joint is flexion, e.g., sitting is
knee flexion because it brings the bones of the upper and lower leg closer
together. Joint extension brings the bones into alignment, e.g., straightening
the legs.Range of motion
. Reps can be done with a full or partial range of motion. Usually the full
range is performed—all the way up, and all the way down. But a few exer-
cises are usually done with a partial range of motion. For example, very few
people squat to where their thighs fold over their calves. So most squatters
only do a partial movement. To squat to a position of full knee flexion, with
a weight that is heavy for the lifter concerned, can be injurious, especially to
the lower back.. Short-range movements of just a few inches are intentionally used in some
programs. ese are called partial reps, or partials. A partial rep could start
at the beginning, middle or end point of an exercise, or specifically from or
to the sticking point. If the partial is over just the final few inches of a rep, it
is often called a “lockout.”Body parts
. Exercises target specific body parts, or muscle groups. In a simplified format
here are the main body parts: