Lesson on the topic “Muscle work”
Answer, when was the working condition of the right hand restored most quickly, during rest or when working with the left hand? What is the importance of active rest for the muscular system?
Conclusion. The functionality of the right hand is restored faster when working with the left hand.
Active rest quickly relieves fatigue of the muscles that took part in the work.
Which work is easier: static work associated with holding a load, or dynamic work associated with moving a load of the same mass?
Why does your back get more tired than your arms when washing clothes by hand?
The back muscles function in a static mode, that is, they help maintain the same posture for a long time. With static force, the muscles are in a state of tension. With the simultaneous contraction of many muscle fibers, the work cannot be very long - the muscles get tired. Hands do dynamic work. The muscles contract alternately.
VII
Reflection
VIII
Homework:
do practical work, prepare messages.
The history of the origins of gymnastics
Physical exercises that would develop various muscle groups to maintain correct posture and muscle performance.
The influence of work rhythm on the development of fatigue
| Rhythm | Hand path, m (S) | Number of movements (n) | Work (in J.) | Onset of fatigue, with |
| Rare | 0,5 | |||
| Average | 0,5 | |||
| Frequent | 0,5 |
A
=
F
•
S
•
n
Make a Conclusion.
Additional material on the topic.
Muscle strength.
One of the physical qualities of muscles is muscle strength.
It is characterized by the magnitude of the maximum tension that a muscle can develop when excited. Muscle strength depends on the mass of contractile proteins, the number of muscle fibers, and the frequency of nerve impulses entering the muscle. The more contractile proteins a muscle has, the greater its strength. The rate of muscle contraction
is determined by the time it takes for the muscle to contract and relax.
The shorter this time, the greater the speed of contraction. Muscle endurance
is their ability to maintain a given rhythm of work for a long time.
Muscle tone
is a state of constant slight tension. Due to muscle tone, body posture is maintained.
Tonic contractions of the abdominal muscles hold the internal organs in a certain position. The tone of the unstriated vascular muscles ensures the required diameter of the vessels, and therefore constant blood pressure. Muscle work
There are static and dynamic work.
During static work,
the muscles are under prolonged tension, but do not change their position in space, for example, when holding a load, in a certain body position.
Static work is very tiring, especially for children and teenagers. During dynamic work,
muscle contraction alternates with relaxation, while the muscles move.
Such work is observed during running, walking, swimming and other movements. Dynamic work is less tiring. Fatigue
Muscle work is accompanied by energy loss. The energy required for muscle contraction is generated by the breakdown and oxidation of organic compounds, mainly carbohydrates. What are the causes of fatigue? When studying static work, it was found that it is not the muscles that get tired first of all, but the nerve centers that regulate the work of these muscles. Therefore, to maintain high physical performance, it is necessary that the nervous system also has high performance. Fatigue during dynamic work occurs for various reasons. The main ones are insufficient oxygen supply to muscles, decreased energy production, and accumulation of breakdown products. The question arises: is fatigue beneficial or harmful? It would seem that the answer is known - harmful. However, from a physiological point of view, fatigue is a beneficial phenomenon. Overwork is harmful. During muscular work, ATP is consumed, which is formed due to the oxidation of glucose. Decomposition products are carbon dioxide, water, lactic acid (lactate). Painful sensations during fatigue are caused precisely by the accumulation of lactate.
