Bodybuilding Forum

lindamethue · Joined: 30 Oct 2006 Posts: 5 Location: australia

"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.
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