No matter what you use to resistance train, the principle behind it is simple. Resistance training breaks down muscle. When muscle is broken down, the body works to repair the damage, rebuilding it stronger and larger than it was before. It is actually the recovery after resistance training that creates the change in muscle!
When you are performing resistance-training exercises, be sure to give the muscles you are working at least forty-eight hours to recover before you work them again. This amount of time allows the muscles to be repaired. Without rest, the muscles cannot repair, leading to faulty movements, muscle imbalances and often injury.