| As above, go slow on the eccentric (downward) portion of the lift, and explosive, but controlled, on the concentric (Upward) portion of the lift. I remember the two terms by thinking "Concentric, sounds kind of like Contracting, which is the upward portion of lifts."Once you know that one, you then know the other one due to process of elimination :P
As crazy said, the eccentric portion of the lift is the most important. You getting some of that info from your DC training I bet, Crazy :P I end all lifts that I can, and that makes sense to, on the eccentric portion of the lift.
Here's a little something on the two parts of the lifts. Gives you some insight into what's happening during the two different phases.
Credit to digitorum for writing the information that follows:
Effects of muscle fibre shortening on fibre damage - concentric action
Firstly, the "sticking point" of a muscle occurs where the muscle fibres shorten to a specific point where maximum force can be produced, although this won’t mean maximum force is produced mechanically because leverages will vary (6). Anyway, as the fibres go past this sticking point as it is called, tension decreases across the length of the fibre and if tension decreases, force is reduced and less damage can be done to the fibres in that portion of the rep (4). This is because the myosin cross bridges involved with binding to the actin within the fibres, become disrupted (4). So, on the concentric portion of your lift, tension will vary (5), meaning it is not the most effective part of your lift to cause fibre damage.
Effects of muscle fibre lengthening on muscle damage - eccentric action
When a muscle fibre lengthens under contraction, the situation is different. The greater the stretch in the muscle fibres, the greater the tension developed and therefore more force can be produced leading to increased levels of fibre damage (4). Muscle fibres do not obey Hooke’s Law of Elasticity, they will exert proportionally more tension the greater the force applied under stretch! (4). This is why pre-stretching the long triceps head and both biceps is effective in French presses and incline dumbbell curls respectively. Also when you lower the weight, it requires more force than needed to raise it, therefore developing more tension even as the fibres continue to lengthen. This is where the most muscle fibre damage occurs (5, 7).
Sarcomeres are the contractile units within the myofibrils which in bundles form muscle fibres, and these contain the actin and myosin proteins responsible for the "sliding filament" contraction (4, 5). During the eccentric lowering of the weight, these proteins are under greater tension since external resistance is greater than muscular force, and their component parts actually break because of this (5, 7). Each rep, more sarcomeres will "break", some on the concentric lift but most on the eccentric. Once you have completed your workout, thousands of sarcomeres at different points along the fibre will have been broken. If you continue to workout after this, you can easily pull your muscle, which occurs because certain muscle fibres have too many broken sarcomeres along their length and the tension delivered by the rest of the muscle is high enough to tear the whole muscle fibre which could not cope because of its weakened state. |