Glossary of Bodybuilding Definitions
Incline Bench – Bench where the body is tilted back in respect to the vertical. Incline benches are primarily used to work the upper-chest region.
Injuries – In bodybuilding terms, injuries are any damage to bone, muscle, or connective tissue. The most common bodybuilding injuries are muscle strains.
Insertion — The point of attachment of a muscle most distant from the body’s midline or center.
Insulin – Hormone secreted by the pancreas responsible for carbohydrate metabolism. This hormone determines if the carbohydrates are to be used for energy, for storage inside the muscle cells as glycogen, or for converting and storing the carbohydrates as fats when they are found in excess in the bloodstream.
Intermediate strength trainer — A person with 6 to 12 months of bodybuilding experience.
Isolation exercise — An exercise that involves just one muscle group and the movement of the one joint that that muscle group crosses. These types of exercises are sometimes called single-joint exercises. Examples are the dumbbell fly, lateral raise, and leg extension.
Isometric – Type of muscle contraction where there is no shortening of the muscle’s length. Isometric exercises were popularized by Charles Atlas.
Isotension – Exercise technique whereby continuous stress is placed on a given muscle. Extending the leg by contracting the quadriceps and holding the position for 10 to 20 seconds or more is an example of isotension. Bodybuilders make use of the technique during the pre-competition phase as it improves muscle separation.
Isotonic – Type of muscle contraction where the contracting muscle shortens. The muscle may also be lengthening, as when doing a “negative.” Most bodybuilding exercises are examples of isotonic contraction.
Joint – The point at which two bones meet. Most joints have a hinge-type structure which allows the bones to articulate over one another.
Knee wrap — A band of elastic fabric that is wound tightly around the knee to support the joint during squats and other heavy leg exercises.
Knurling — A grooved or roughened area along the gripping portion of a barbell or dumb¬bell that lessens the tendency for the hand to slip.
Lactic Acid – A product given off during aerobic respiration. Lactic acid was once thought to be strictly a waste product, however recent evidence suggests that a version of lactic acid called lactate is used by the liver to replenish glycogen supplies.
Latissimus Dorsi – Called the lats, these large fan shaped muscles are located on the back of the torso, and when properly developed give the bodybuilder the characteristic V-shape. The lats function to pull the arms down and back.
Layoff – Any time spent away from the gym is called a layoff. It can be referred to as a training vacation.
Lean body mass — Total body mass minus fat mass; this includes muscle, bone, organs, and water.
Lifter — Slang term that refers to a person who regularly strength-trains.
Ligament – Fibrous connective tissue that joins one bone to another.