Importance of understanding the difference between muscular contractions! • A concentric contraction causes muscles to shorten, thereby generating force. • Eccentric contractions cause muscles to elongate in response to a greater opposing force. • Both Concentric and Eccentric contractions can be refereed to as Isotonic Contractions. Isotonic contractions generate force by changing the length of the muscle. • Isometric contractions generate force without changing the length of the muscle. WHY IS THIS IMPORTANT TO UNDERSTAND? During any exercise you are stronger on the eccentric contraction. Your body is able to recruit more muscle fibres, allowing you to have more control when lengthening your muscle. If the body was unable to control eccentric loading, the muscle would easily be at risk of over lengthening, potentially creating tears in muscle fibres, tendons and ligaments, resulting in INJURY!
When exercising most people empathise the concentric (shorting of the muscle). But we know we can control more load (weight) eccentrically. More empathise should be put on eccentric part of the movement. In a program you will commonly see tempo ratios such as 2:2 or 2:1:2 2 numbers for example: 2:2 simple means, 2 seconds concentrically, 2 seconds eccentrically. 3 numbers for example: 2:1:2 simple means, 2 seconds concentrically, 1 second isometric, 2 seconds eccentrically. It’s important to take not of ratios when following an exercise program, for example: Barbell Back Squat, 50kg, 5sets, 5 reps tempo 5:1:2. 5 Seconds eccentric (lowering) 1 second isomeric (pause) 2 second concentric (raising).The exercise would be 10x harder with a tempo such as this, compared to a generic 2:1 tempo. Why would it be 10x harder? The force is applied for a greater length of time, this is referred to as time under tension.