Type 2B - These fibres, also called fast twitch or fast glycolytic fibres, contain a low content of myoglobin, relatively few mitochondria, relatively few blood capillaries and large amounts glycogen. Type 2B fibres are white, they are geared to generate adenosine triphosphate or by anaerobic metabolic processes, they are not able to supply skeletal muscle fibres continuously with sufficient ATP, they tire easily, they split ATP at a fast rate and have a fast contraction velocity. These fibres are found in large numbers in the muscles of the arms. The sporting event that is related to type 2B fibres is athletics and the event would be Shot Put.
Muscle Movement
Agonist – This is used to describe a muscle that causes specific movement or possibly several movements to occur through the process of its own contraction. For an agonist to be effective as a mover in the skeletal system it must actually cross one or more structures that can move. This is where the muscle crosses a joint by way of a connecting tendon.
Antagonist – Antagonist muscles are found in pairs and are called antagonistic pairs. These consist of an extensor muscle, which "opens" the joint thereby increasing the angle between the two bones. The flexor muscle does the opposite to an extensor muscle.
Antagonistic pairs are needed in the body because muscles can only exert a pulling force, and can't push themselves back into their original positions. An example of this kind of muscle pairing is the biceps and triceps muscles.
When the biceps are contracting, the triceps are relaxed, and stretches back to its original position. The opposite happens when the triceps contract.
Synergist - Synergist muscles stabilize muscle movements to keep them even, they control the movement so that it stays within a range of motion which is safe and desired. These muscles can also be seen as helping hands; they focus on the effort of movement by creating a high level of control. By working synergistically, these muscles also reduce the amount of work they need to do, which can improve endurance.
Fixator - Fixators are designed to fix or stabilize a joint. For example, when people stand up, Fixator groups at the ankles keep the joints stable so that the ankles will not bend or wobble, causing difficulties with balancing. Fixator groups are also what allow people to isolate movements to a specific joint or area of the body, with the muscle group holding nearby joints in place.
Types of Contractions
Isometric – This muscle stays the same in length as it works and so no movement occurs. For example, the muscles in the vertebral column contract isometrically to help maintain our posture.
Concentric – A concentric contraction is a type of muscle by which the muscles shorten while generating force.
Eccentric - An eccentric contraction occurs when a muscle is contracting, and an external force is trying to lengthen the muscle. The classic mechanism for a muscle strain is an eccentric contraction.
Sliding Filament Theory
The sliding filament theory is the method by which muscles are thought to contract.
At a very basic level each muscle fibre is made up of smaller fibres called myofibrils. These contain even smaller structures called actin and myosin filaments. These filaments slide in and out between each other to form muscle contractions; because of this we have the “sliding filament theory”!
The diagram above shows part a myofibril called a sarcomere. This is the smallest unit of skeletal muscle that can contract. Sarcomeres repeat themselves over and over along the length of the myofibril.
Response to Exercise
Short Term – When you exercise there is a build-up of lactic acid in the muscles, this happens when there is no oxygen in the muscles and this can also lead to cramp. Another short-term effect of exercise is where you tear your muscles, this can happen when you are exercising, the muscle tears and then repairs itself with muscle fibres, this will increase the size and mass of the muscle.
Long Term –
- Increased numbers of mitochondria means an increase in the rate of energy production.
- The muscles, bones and ligaments become stronger enabling them to cope with the additional stresses and impact put on them.
- The amount of myoglobin within the skeletal muscle increases, which allows more Oxygen to be stored within the muscle, and then transported to the mitochondria.
- Muscles are capable of storing a larger amount of glycogen for energy.
- Enzymes involved in energy production become more concentrated and efficient to aid the speed of metabolism.
Hypertrophy - Is when a cell, in this case a muscle cell, increases in size through growth. Extreme hypertrophy may result in the cells splitting to create new ones.
Increased Strength of Tendons - Tendons become stronger with regular exercise as it causes them to stretch further than normal. In response to the stresses that exercise places on tendons, the tendons will increase the number of collagen fibres in them. The collagen fibres form a matrix or cross like structure within the tendon; and so with more collagen fibres present the matrix is a lot denser and strengthens the overall tendon. This will then allow you to put even further stresses on the muscles and tendons during exercise.
Analyse D2
The short-term effect of exercise on the muscular system is that lactic acid builds up in the muscles, this happens when there is no oxygen to the muscles, this can lead to cramp. You also tear your muscles when you exercise, the muscle tears and then repairs it with muscle fibres, which will increase the size and mass of the muscle.
The long-term effects of exercise are that you have an increased numbers of mitochondria, this means an increase in the rate of energy production. The muscles, bones and ligaments become stronger to help cope with the additional stresses and impact that is put on them. The amount of myoglobin within the skeletal muscle increases, which allows more Oxygen to be stored within the muscle, and transported to the mitochondria. Muscles are capable of storing a larger amount of glycogen for energy, the enzymes involved in energy production become more concentrated and efficient to aid the speed of metabolism. Hypertrophy is a long-term effect of exercise; this is when the muscle cell, increases in size through growth. Extreme hypertrophy may result in the cells splitting to create new ones. Another long-term effect of exercise is the increased strength of tendons; tendons become stronger with regular exercise and this causes them to stretch further than usual. If you have strong tendons they will help prevent strains and any other injuries.
In my opinion there are more advantages than disadvantages to regular exercise as it is a fun and healthy way to improve the muscular system.