• Question: why do your muscles get bigger when you exercise :)

    Asked by 264sprg52 to Andrew, Dan, Emilia, Helen, Katy, LauraAnne, Stephanie on 7 Nov 2016.
    • Photo: Dan Gordon

      Dan Gordon answered on 7 Nov 2016:

      This is a great question. Within the muscle there are what are called sarcomeres these sarcomeres are made up of tiny filaments of protein termed actin and myosin. You need to image that these filaments not only run parallel to each other but also above and below each other. It is these that give the muscle its structure.
      So when you start to do strength training the muscle structures are put under loading (tension). this tension triggers a series of responses. the first which is the short-term 0-8 week response is that the muscle gets stronger but not bigger, why? Well this is because the muscle innervated by the nerve or motor unit. So the result of the strength training is that more muscle fibres become recruited for the same amount of work but we don’t get bigger. however as long as we keep applying the training we start to see some neat responses to the muscle structure. We see something called satellite cell proliferation where the fibres start to split, but never detach, by doing this we get an increase in size (we will come back to this in a moment). Secondly we see what is called myofibrillar proliferation. This is where when the force is applied and taken away there is some micro damage to the structure, but this time rather than structure simply reconnecting in the way they were, they start to align them selves in response to the direction of which the force was applied. As such the muscle becomes more capable of generating force.
      I mentioned the size response. This only occurs in recovery not during exercise and is proportional the amount of tension (weight) and the amount of growth hormone that is released. this hormone is what triggers the building of the bigger structures. This whole process of getting bigger wont happen for at least 8 weeks though. Also of note is that you increase the size of the muscle fibres but ever the number, the number is genetically set.

    • Photo: LauraAnne Furlong

      LauraAnne Furlong answered on 9 Nov 2016:

      Dan has given a great answer, the muscles, tendons and bones in your body get stronger because you are applying forces to them. When you apply the force, you cause a little bit of damage to them, and this triggers the response Dan describes below. The important bit to remember when you are trying to get your muscles to be as big and strong as possible, is that this process takes a bit of time. You can’t exercise in the morning and have stronger muscles by the afternoon, or even in the next day or two after.

      You need to allow some time for the changes in the muscle to occur to allow it to get stronger, so usually an athlete won’t work the same muscle group in the same way for two days in a row. This is called recovery, and is an important part of player and athlete management to make sure they don’t overtrain and get injured. If you exercised the same muscles hard for several days in a row, instead of making them bigger you would end up making them very tired and sore, and getting them back to normal would take much longer. You need to make sure you’ve fed yourself properly help the muscle recover – protein is found in milk, meat and eggs and is very important for this. As Dan points out, the timeline for making your muscles bigger is actually quite long, so it could easily take several weeks to see a change.

Comments