What follows is an essential guide to the most commonly used terms in the gym. Take a few minutes to familiarize yourself with them, and you'll feel more comfortable and competent whilst working out. After all, knowledge is power.

Aerobic: Low intensity, longer duration exercise that temporarily increases heart rate as a means to improve the efficiency of oxygen consumption by the body. Bodybuilders use aerobic exercise to burn calories and lose excess fat.

Anabolic: Relating to the phase of metabolism where simple substances are transformed or synthesized into complex materials of living tissue. Lifting weights at a high level of intensity triggers anabolism.

Anaerobic: High intensity, shorter duration exercise that primarily uses glucose rather than oxygen. Lifting a heavy barbell is anaerobic.

Barbell: A six or seven-foot bar that holds plates of different sizes and weights. This is the principle tool of strength training.

Biceps: The large muscle at the front of the upper arm. Also referred to as biceps brachii.

Cardio: Aerobic exercise mostly intended to expend calories and burn fat, and of course, strengthen the heart.

Concentric Contraction: Also called the "positive" movement. The contraction of a muscle against gravity, such as pressing a barbell upward during a bench press or pulling the lat bar downward during a pulldown.

Cycle: Refers to deliberate variation in the intensity and volume of workouts, or to variation of dosages of steroids or other growth-enhancing drugs.

Definition: Term that refers to having low body fat that permits muscles to stand out in bold relief.

Deltoids: A triangular muscle that covers the shoulder joint and is used to raise the arm from the side.

Dumbbell: A short bar that holds a few plates and is held with one hand. Useful for wrist and forearm exercises, but otherwise far less useful than a barbell.

Eccentric Contraction: Also called the "negative" movement, it's the lengthening of a muscle while under tension, such as lowering a barbell during a bench press or a barbell curl.

Forced Reps: Extra repetitions of an exercise assisted by a spotter who bears some of the weight.

Glutes: The group of the three large muscles of each buttock that extend, abduct and rotate the thigh.

Hamstrings or Hams: The group of three muscles constituting the back of the upper leg that serve to flex the knee joint, abduct the leg, and extend the thigh.

HIT or High Intensity Training: The method of training that stresses brief, intense workouts over longer, less intense workouts.

Intensity: Used loosely as the degree of difficulty of a given exercise or workout. More accurately defined in Power Factor Training as the amount of weight lifted per unit of time. (e.g. "I can bench press 3,750 pounds per minute.")

Isolation: The technique of working a single muscle rather than a larger muscle group.

Isometric Contraction: Keeping a muscle under tension without eccentric or concentric motion.

Lactic Acid: A waste product of glucose and glycogen metabolism produced in the muscles during intense exercise. Causes pain and soreness.

Lats: The latissimus dorsi muscles are either of two wide, flat, triangular-shaped muscles that run from the vertebral column to the humerus. Their development creates the V-shaped torso.

One Rep Max (1RM): The heaviest weight with which a person can complete one full repetition. (e.g. "My max rep on the bench press is 325 pounds.")

Pecs or Pectorals: The large muscles of the chest.

Pump: The feeling of muscles when they are engorged with blood after intense exercise.

Quadriceps: The large, four-part muscle at the front of each thigh. Primarily used to extend the leg at the knee.

Range of Motion (ROM): Refers to the limits of motion of the joints and muscles associated with an exercise.

Reps or Repetitions: One complete movement of an exercise from start to finish. For example, on a bench press, lowering the bar from full extension to the chest and back up to full extension.

Rotator Cuff: The group of muscles and tendons that secures the arm to the shoulder joint and allows for easy rotation of the arm.

Ripped: see "Definition."

Set: A group of consecutive repetitions. (e.g. "I did three sets of 12 reps on the bench press.")

Smith Machine: Equipment that allows an integrated barbell to slide up and down along vertical rods using bearings for smooth motion. Usually incorporates several safety stops to limit the range of motion.

Split: Dividing exercises into groups performed during separate workouts.

Spotter: Partner who, if necessary, assists in placing heavy weight into position and acts as a safety in case fatigue prevents lifter from completing a repetition.

Static Contraction Training: Training method using accurately measured isometric contractions in only the strongest range of motion in order to maximize intensity.

Superset: Technique of combining two exercises, which are done in immediate succession for the same muscle or muscle group. (e.g. "For my triceps, I did a superset of close grip bench presses followed by weighted dips.")

Triceps: The large three-part muscle that runs along the back of the upper arm.

Volume: Refers to the quantity of exercise in a workout rather than the intensity. Volume and intensity are inversely proportional.

Workout: A combination of exercises performed in succession with brief rest periods between them.