We have three different muscle contractions with exercising and they are concentric in which the muscle shortens, eccentric in which the muscle lengthens and isometric which you are in a fixed position. When you think of a bicep curl you are having eccentric movement as you bring the dumbbell up squeezing the bicep and then eccentric when you stretch and lengthen the bicep head as you extend the arm, however there is isometric movement when you hold the squeeze, and it is the strongest at the point eccentric movement cause you do not have momentum on your side you are going against everything bringing the weight down controlled. Next we are doing a tricep extension which you have concentric and eccentric contraction but not isometric. And once again your strongest at the point of concentric because you are almost relaxing at eccentric. With a lateral raise you have concentric bring weight up, eccentric bring weight down and if you hold at the top of the movement isometric. And the strongest point would be the down of the eccentric movement. With a quad extension you have all three contractions concentric with flex up, eccentric when you bring it down, and isometric when you hold the squeeze. The strongest movement here would also be the eccentric contraction because you’re generating tension in the muscle that of which is 50% greater than concentric. In a hamstring curl the concentric would be the curl of your heel back, eccentric the heel coming all the way back out extended and isometric when you hold the weight at the top of the contraction. The strongest contraction would again be the eccentric movement creating a stronger tension. Now a shoulder press we have the concentric with push upward, eccentric with the downward movement and then isometric with the hold at the top of the contraction. The strongest contraction is the eccentric slow steady down. With a front raise you have the concentric movement with the raise, eccentric with lowering of the weight, and isometric with the hold at the top. The strongest contraction is again the eccentric because the tension is so high on the down motion. A squat you’re gunna have a concentric movement pushing up, an eccentric with the down part of the squat ands isometric at the top of the squat holding. The strongest contraction would be the eccentric because the tension is the greatest at the bottom of the squat. With a lat pull down you have the concentric movement with the lat pull with the downward movement and contraction of the lat, eccentric wen you extend back up, and then isometric when you hold the lat pull down at the bottom. The strongest contraction will be the eccentric up controlling all the tension up. A back row you have the concentric movement when you bring the weight toward the body, the eccentric when you slowly bring the weight out, and the isometric when you hold the squeeze at the top. The strongest contraction is the eccentric when you bring the weight down controlled from the squeeze at the top. What I learned is where the contraction is the strongest and felt the difference as well so now I have something to show and tell to clientele to help them better understand the workouts.