Why do my muscles shake and feel the burn?
When you feel a burning sensation in your muscles, it is a sign that they are working anaerobically (without oxygen). This “burning” is a build up of lactic acid within the muscles, due to muscle fatigue. You will generally have to stop exercising momentarily in order to stop any further build up.
Once you have stopped for a few moments, the sensation will cease and you will be able to continue once again. The stronger your muscles get from regular practice, the longer it will take for this burning sensation to appear (if at all). Muscles can also shake during exercise and this is a sure sign that they are working hard.
This is a good thing but recognise when they are getting too shaky and you are losing proper technique, as it is time to rest when this happens.