Resistive force; the force generated by a factor to the external body
Torque; the degree in which a force tends to rotate an object.
There are three different types of levers in the body; First-class, Second-class and Third-class.
First-class; when the muscle force and resistive force is on different sides of the fulcrum e.g. the head resting on the vertebral column. As the head is raised, the facial portion of the skull is the resistance, the fulcrum is between the atlas and occipital bone, and the effort is the contraction of the muscles of the back.
Second-class; when the muscle force and resistive force act on the same side of the fulcrum, with the muscle force acting through the level longer than that through which the resistive force acts - e.g. raising the body up onto the toes. The body is the resistance, the ball of the foot is the fulcrum, and the effort is the contraction of the calf muscle.
Third-class; most of the limbs in the human body are third-class levers. When the muscle force and resistive force act on the same side of the fulcrum, with the muscle force acting through the lever shorter than that through which the resistive force acts - e.g. adduction of the thigh. The weight of the thigh is the resistance, the hip joint is the fulcrum, and the contraction of the adductor muscle is the effort.
Heat production;
The ability of being able to maintain body temperature. However, when a muscle contracts this produces around 70% of body heat due to the energy produced in the muscle tissue. Blood is another essential element in temperature control; this is because during exercise, heat from the body core and working muscles is redirected to the skin when the body is overheating. When the internal heat of the body reaches too low of a level thermo receptors in the skin relay a message to the hypothalamus in the brain. In response to this signal, the skeletal muscles contract and then relax in involuntary (shivering) increasing muscle activity to generate heat. Muscles are also responsive to exterior heat - cold air increases muscle tone, and hot conditions have a relaxing effect on muscles.
Maintenance of posture;
The ability of being able to keep a certain position e.g. sitting or standing. Also, As well as enabling movement, muscles also maintain the body’s posture and position. Sensory receptors in the muscles monitor the tension and length of the muscles and provide the nervous system with crucial information about the position of the body parts, therefore enabling posture to be maintained. Muscles are never completely at rest, nor do they actually have to shorten in length when they contract. The tension or tone produced as a result of these contractions between various opposing groups of muscle helps us remain in a static position, even when we are asleep.
There are two different types of muscle fibres; Type 1 and Type 2.
Type 1; which is also known as slow twitch, they contract more slowly which enables you to keep going for a long time. Slow twitch fibres are good for endurance activities such as cross country, as they work for a long time without getting fatigued. Usually slow twitch fibres are red because they are rich in oxygen that provides the energy for the muscles.
Type 2; more commonly known as fast twitch fibres, they contract a lot quicker but are easily fatigued. They use anaerobic metabolism to create fuel. Fast- twitch fibres can be split into two groups; Type 2a and Type 2b.
Type 2a; also known as fast-oxidative-glycolytic, have a quick contraction speed they are generally used for aerobic metabolism, and are able to use either glucose or fats as a source of energy.
Type 2b; also known as fast glycolytic, have a quick contraction speed and are only recruited for brief maximal efforts they are easily fatigued. They are what most people would think of as sprinters muscle fibres, and are therefore of no use for sustained performance.