Muscle Contraction Research Paper

MUSCLE CONTRACTION AND FATIGUE

BACKROUND INFORMATION:

Muscles make up about 40 to 50 % of the male body and 30 to 40 % of the female body. In that case we can conclude that the muscles play a very important role in our body. But one of the most important things about muscles is their ability to contract and help us with movement. The first step of a muscle contraction would start with the brain. The brain sends an impulse to the muscle, which then travels down through the motor neuron to the neuromuscular junction, to which it then lets out acetylcholine. The impulse then travels through the sarcolemma and transverse tubules (T- tubules). While the impulse passes through the transverse tubules, the sarcoplasmic reticulum releases calcium

Now this cycle continuously runs until the impulse comes to a halt. Now, once the impulse stops and action potential has stopped, relaxation in the muscle takes place. In muscle relaxation calcium ions are released from troponin and tropomyosin covers up the binding site, which stop contraction. And finally, calcium returns to the sarcoplasmic reticulum where it awaits its next impulse, to start this entire cycle over again. Muscle contraction is a very complicated process, but with a lot of it comes muscle fatigue. For example, when your running your muscles are consistently contracting at a very fast pace, and about a few minutes into running, your body begins to feel heavy, you begin running at a slower pace, and your muscles begin to burn and tighten. To sum it up, Fatigue is tiredness that is caused by muscles going at a lower rate in their ability to produce movement. In muscle fatigue, muscles can no longer respond to signals sent from the nervous system. When doing high intensity workouts, fatigue can be caused by the need for more oxygen in the body. As you exercise your muscles begin to work harder, and they need more oxygen then when they were relaxed. When oxygen

But when the body runs out of the oxygen supply, that glucose gets turned into lactic acid, causing the power output to decrease and the fatigue to take over. Although, fatigue is in ongoing research, medical doctors think it can be due to these two reasons: the leakage of calcium and the failure of action potential to release acetylcholine. When calcium continuously leaks into the muscle, the force produced by the muscle begins to weaken, and the calcium also triggers a “protein- digestive enzyme that ruins muscle fibers”. The damage to those muscle fibers can cause a slight amount of pain or tightness in the muscle that leads to fatigue faster than normal. Acetylcholine gets broken down by an enzyme, acetylcholinesterase, (AChE). AChE enzyme, which is bonded to collagen fibers in the “extracellular matrix of synaptic cleft” allows for the breakdown of acetylcholine into acetyl and choline, which are products that cannot activate the ACh receptor. Therefore, the action potential in