The importance of adopting good form and technique in order to avoid injury and fast track your progress cannot be stressed enough.
The most common reason that people don’t lift weights correctly is because they try to lift more than they are capable of. The tendency to use too much weight typically results in poor form, which decreases your ability to get results and increases your risk of injury.
Exercising through a full range of motion
Ideally you want to work each target muscle through its natural range of motion for complete development and reduce the risk of injury. Range of motion refers to the distance and direction that a joint can move between the flexed and extended position. Ideally we should try to perform each exercise through a full range of motion (i.e. from complete extension to complete contraction). There is evidence to suggest that we recruit more muscle fibres in an exercise when the muscle is loaded from the fully stretched position and an emphasis is placed on the end of the positive phase. In other words, the position of peak contraction is emphasised by squeezing really hard at the completion of each eccentric repetition. Another benefit to lifting through a full range of motion includes the stretching of the antagonist muscles (the muscles that act in opposition to the agonist), as well as enhancing both muscle strength and joint flexibility, when executed with proper lifting technique.
Maintaining constant tension
You should ideally look to maintain constant tension throughout the movement and avoid locking out the joint as a mean to rest, as this decreases intensity. Locking out on an exercise where you are employing peak contraction in order to increase stress on the muscle (as in the fully extended position of tricep pushdowns) is quite different to locking out as a means to rest between reps by taking tension off the muscle (as in locking your knees out at the completion of each leg press rep).
Focussing on the negative (eccentric contraction)
Concentrate on the negative portion of the lift by trying to lower the weight at the same pace, if not slower than you lifted it. Research indicates that it is the negative (eccentric) portion of the lift that is responsible for imposing the stress and micro-trauma on muscle fibres, which leads to more shapely muscles.
Slow down rep speed
One of the most common mistakes I witness in the gym is the use of speed and momentum to lift the weight, followed by a total lack of focus and control when the weight is lowered. Simply slowing rep tempo, or timing as it is commonly referred to, by consciously squeezing (not swinging or bouncing) the weight up and then lowering it slowly under control can increase exercise intensity significantly and imposes significantly more stress on the working muscles, which leads to better results from your training.
Achieving peak contraction
Emphasise the position of peak contraction by squeezing really hard at the completion of each eccentric repetition. As mentioned previously, this helps recruit a maximum number of muscle fibres and some experienced trainers also believe that regularly focussing on peak contraction stimulates growth in areas of the muscle otherwise not stimulated. As such, over time, this actually improves the shape and refinement in that muscle.
Avoid ballistic changes of direction of movement
When transitioning from the eccentric portion of the rep into the concentric phase, there should be no bouncing or fast change in direction. The weight should be lowered slowly and deliberately to the fully extended position and then the change of direction should be initiated with a deliberate and controlled contraction (think of squeezing the weight up rather than “ballistically bouncing” it up). The practice of bouncing out of the bottom position in exercises such as lying leg curls and bench press in an attempt to lift more weight or extend a set past positive failure has resulted in more severe muscle tears and ruptures than any other.
Consider exercise sequence
It is generally advisable to proceed from the larger muscle groups to the smaller muscle groups during a workout. This allows optimal performance of the most demanding, major body-part movements when you are at your freshes, and you are more likely to have better weight lifting technique when fatigue is low and focus is high.
By Mario Van Biljon, Body Guru