You lose flexibility when building or strengthening muscles?  I used to believe exactly this, and still people say “my muscles are very tight because I do weight training and don’t stretch”.   These are the factors that bust the myth: Firstly, effectively warming up.  Secondly, doing muscle building exercises in full range. Thirdly, focusing on the eccentric phase of an exercise.  These 3 factors mean that you will not only gain muscle and strength but increase your flexibility while strength training.

1. Warming up

Warming up stretches, tenderises and prepares the muscles.  Put simply, warming up means that the muscles get switched on, ready to be put under pressure through some form of resistance training.  Just so we are on the same page; stretching is not warming up.  Stretching is relaxing muscles and the whole body, that’s not our goal if we want to build muscle and flexibility.  If we want to build muscle and flexibility in our legs, warm-up with the legs, and visa versa with the upper body.  Alternatively, we can use the same exercise to warm-up as we use to build muscle, just with less weight or less pressure.  5 – 10 minutes is generally enough or until your body feels ready and warm in the area to be used.

It is important to warm-up the body area or part that will be used in the strengthening.

2. Doing muscle building exercises in full range

This is major in BUSTING the MYTH.

Every muscle attaches at some area of the body and inserts at another area.  In between is connective tissue and MUSCLE.  If we only use a small range of motion when exercising, than over time the muscles will become shorter.

BUT, interestingly, if we use the muscle through it’s full range under resistance, the muscle will actually lengthen and flexibility will increase.

I often see people training in short range of movements, so even though their muscles can stretch out longer, they only do between 50-70% range of movements, this is telling the body that we want it to shorten, and we don’t want the length.

Full range of movement is best achieved using slow movements.

3. Focusing on the eccentric phase of the exercise


When focusing on performing an exercise in the Eccentric Contraction, where the movement lengthens the muscle, (as seen in the second movement in the picture), it increases flexibility.

If it is done slowly and through full range, it will INCREASE flexibility.

Often this is where the myth of losing flexibility through muscle building comes from, often we do the Concentric Contraction slowly (as seen in the first movement in the picture) and then just lower the weight quickly in the second phase, this type of training may shorten the muscle and not build strength and muscle  as well either.   However, building the most muscle and strength can be achieved by doing both the concentric and eccentric phases slowly.

To bust this myth:

WARM-UP the muscle we are about to train + Do the exercise through full range of muscle movement + Focus on slowing down through the eccentric phase = Strong and Flexible Muscles