Weight Training Biomechanics and Kinesiology Terms

adduction/abduction

abduction and adduction refer to motions that move a structure away from or towards the center of the body.

abduction

abduction occurs when a body part moves away from the midline of the body. when you lift your arms so your hands are level with your shoulders (like you would in lateral raises), that's abduction of the shoulder. when you shove your knees out in a squat, that's abduction (the outside muscles of your butt are the primary abductors).

internal/external rotation (medial/lateral)

internal rotation is rotation of an appendage towards the midline of the body. external rotation is rotation away from the midline of the body.

midline

a kinesiology term describing an imaginary line running down the middle of the body, and separating its right and left sides.

supplemental exercise

a supplemental exercise is usually a compound exercise performed immediately after the main exercise for the purpose of bolstering, supporting, and improving the main exercise. for example, if bench press is your main exercise for the day, you may then switch to heavy dumbbell bench presses as the supplemental exercise for the day.

plyometrics

a type of exercise that involves a rapid eccentric contraction followed quickly by explosive concentric contraction. used to increase power and speed. the most common plyometric exercises involve jumping movements. usually you jump down from a box and then immediately jump back on top of it over and over again. care must be taken with plyometrics as they put a lot of stress on the joints and tendons. other plyometric options are explosive push-ups, and various medicine ball throws.

accessory/auxiliary exercise

accessory exercises are performed after the main and supplemental exercises for the purposes of increased work capacity, antagonist muscle training (the opposite of the main muscle groups you just trained), hypertrophy, prehab, rehab, and support of the main lifts. pull-ups, bicep curls, and ab work are good examples of auxiliary exercises to a barbell strength training program.

adduction

adduction is when body parts move towards the midline of the body. when you lower your arms down to your side that's adduction of the shoulder. when your knees come back in as you stand up in a squat, your adductors (the inside of your thigh) are at work.

compound movement

exercises or movements that involve more than one joint and muscle group. squats, deadlift, bench press, shoulder press, power cleans, and pull-ups are examples of compound movements. the benefits of compound movements are many; they give the biggest bang for your buck for the time spent on them, they work the body as a complete system instead of piece-by-piece, they create a major hormonal response that causes your body to produce more testosterone and growth hormone (naturally), and they get you bigger and stronger faster than anything else.

isolation movement

exercises or movements that involve only one joint and a limited number of muscle groups. examples: bicep curls, leg curls, hamstring curls, tricep extensions. the benefits of isolation movements are almost entirely aesthetic — they cause more sarcoplasmic hypertrophy (muscle storage growth) than heavy compound movements, which can lead to larger-looking muscles, but not necessarily stronger muscles.

extension movements

extension movements increase the angle between a segment and its proximal segment. straightening your elbow in a tricep pushdown is extension. rising up from a squat uses hip and knee extension. straightening up in a deadlift also uses hip and knee extension.

flexion movements

flexion movements decrease the angle between a segment and its proximal segment. bending the elbow towards you in a bicep curl is a flexion movement because the angle between your forearm and bicep decreases. squatting down is a flexion movement because the angle between your thigh and calf decreases.

flexion/extension

movements that affect the angle between two parts of the body.

supination/pronation

rotation of the foot or forearm so that the sole or palm face anteriorly (supination) or posteriorly (pronation). when your palms face out from your body, they're in a supine position; when they face in, they're pronated. "overhanded" grip on deadlifts or pull-ups is pronation. "underhanded" grip is supination.

isometric contraction

the contraction of a muscle without significant movement. for example, this is what your back, spinal erector muscles, and abdominals do during a squat or deadlift. they are in isometric contraction, but they aren't the muscles doing the prime moving of the barbell. really your entire "core" works this way. its job is to stabilize, via isometric contraction, the entire trunk, so that no energy is lost between the base of support (the floor) and the load (the barbell). another example, is when bodybuilders "flex" their muscles to force blood into the muscles without actually moving the joints that the muscles cross.

concentric contraction

the contraction of a muscle, resulting in its shortening. when you curl a dumbbell up towards your body, that's concentric contraction. concentric contractions generally cause less soreness and inflammation than eccentric contractions.

eccentric (negative) contraction

the lengthening of a muscle under load. it's the contraction that occurs in the "negative" or lowering part of a movement. for example, when you're lowering the bar to your chest on the bench press, you experience an eccentric contraction in your chest muscles. eccentric contractions generally cause more soreness and inflammation than concentric contraction, because more muscle damage occurs during this portion of the movement.

stretch reflex

when a muscle is quickly lengthened under load (eccentric phase) a rebound effect takes place much like a quick stretching of a rubber band. this is why it is harder to pull a deadlift from the floor and reset each rep than to touch-and-go each rep after the first rep. it would also be much more difficult to start a bench press or squat from the bottom as opposed to the top.