C2 - Muscular System

• Hypertrophy:

  • If you exercise with some sort of resistance, it will stress the skeletal muscle
  • This actually results in parts of the muscle breaking which is called a micro-tear
  • The more you stress the muscle with heavier weights, the more the muscle breaks down
  • After having rested and eaten the right foods, the body then starts to repair itself and will actually mend the muscle tissue and make it bigger and better than before
  • If you continue this process, the muscle tissue will keep getting bigger, which will result in an increase in your muscle size - this is called hypertrophy
• Hypertrophy is an increase in the size of skeletal muscle
• Muscular Strength:

  • The amount of force a muscle can produce is related to its size: the larger the muscle, the more force it can produce
  • Force is another way of measuring strength
  • Therefore, the larger the muscle, the more strength it can produce
  • In order to increase a person's strength, they will need to undergo muscle hypertrophy which can only occur from resistance training
  • The area in which an increase in muscle strength is required will determine which muscles are included in a strength training programme
• Muscular Endurance (Myoglobin, Mitochondria, Glycogen and Triglyceride Stores):

  • Aerobic endurance training will also increase muscular endurance for the muscles that are utilised in the training
  • A person could use resistance training with high reps and low loads to increase their muscular endurance of specific muscles
  • The adaptations on the body from this type of training are to help the muscles to contract for long periods of time, which means the aerobic energy system will need to be the main form of energy provision
• Muscular Endurance (Myoglobin, Mitochondria, Glycogen and Triglyceride Stores):

  • Much of the adaptations that occur to the muscle tissues from muscular endurance training are to help to increase the amount of oxygen available to the working muscles and also increase the amount of energy that can be supplied by the aerobic energy system to the muscles, as the aerobic energy system supplies most of the energy during muscular endurance exercises
• Muscular Endurance (Myoglobin, Mitochondria, Glycogen and Triglyceride Stores):

  • Myoglobin is used to store oxygen in muscle tissues
  • Myoglobin combines with oxygen to form oxymyoglobin
  • Oxymyoglobin is used as an oxygen storage site for when the body is in oxygen deprivation
  • When a person is exercising and the oxygen supplied by the blood is not sufficient, this storage of oxygen in myoglobin in the muscle tissue will help to meet the oxygen requirement to produce energy
  • Through muscular endurance training, these stores of myoglobin are increased, which means there is more oxygen available
• Muscular Endurance (Glycogen and Triglyceride Stores):

  • The muscles will increase their stores of glycogen and triglycerides - both of these are sources of energy for the aerobic energy system
  • More energy is readily available in the muscle tissues to produce ATP
  • There is a significant increase in the number of mitochondria in muscle tissue from muscular endurance training
  • The energy production from the aerobic energy system takes place mainly in these organelles, so having more mitochondria in muscle tissues means even more energy can be produced by the aerobic energy system
• Muscle Tone:

  • Muscle tone is the contraction of muscles while a person is at rest: the more toned the muscles, the firmer they feel when the muscles are relaxed
  • From regular participation in exercise, muscle tone increases
  • Increased muscle tone helps a person to maintain their posture so that they have an upright stance, with shoulders back and stomach drawn in
  • Muscle tone helps a person to maintain their balance
  • High levels of muscle tone help a person to generate heat
  • A person with more muscle tissue will have a higher metabolic rate
• Hyperplasia:

  • Hyperplasia is the increase in number of muscle fibres
  • There is some debate as to whether adaption to exercise does actually lead to an increase in muscle fibres themselves or whether it is just an increase in the muscle fibre size that results in muscle hypertrophy
• Adaptation of Muscle Fibre Types:

  • Muscle fibres types will adapt to training by increasing in size - high intensity training results in hypertrophy if fast twitch fibres whereas low intensity training will lead to hypertrophy of slow twitch muscle fibres
  • The type of training carried out will determine how type IIx muscle fibres adapt
• Adaptation of Muscle Fibres Types:

  • In response to low intensity endurance training, type IIx fibres will convert so that they are more like type I muscle fibres which have a slow contraction speed and produce low intensity contractions
  • In response to high intensity training, they convert to become more like type IIa fibres which contract with high force for short periods of time
• Capillarisation:

  • Aerobic endurance training has the effect of increasing the number of capillaries in the muscle fibres, which helps to increase the diffusion rate of gas exchange in the muscles
  • This therefore increases the amount of oxygen entering the muscles from the blood stream, as well as the amount of carbon dioxide leaving the muscles into the blood stream