Cambridge tech the muscular system

Movement and active muscle at the shoulder

Movements: 

Flexion, Extention, Abduction, Adduction, Horizontal flexion, Medial roatation and Lateral rotation.

Active muscles:

Anterior deltoid, Posterior deltoid, Deltoid, Latissimus dorsi, Pectoralis major, Trapezius and teres major

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Movement and active muscle at the Elbow

Movement:

Flexion and Extention

Active muscles:

Biceps brachii and Triceps brachii

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Movement and active muscle at the Radioulna

Movement:

Pronation and Supernation

Active muscle:

Pronator teres and Supinator muscle

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Movement and active muscle at the wrist

Movement:

Flexion and Extention

Active muscle:

Wrist flexors and extensers 

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Movement and active muscle at the vertebral

Movement:

Flexion, Extension and Lateral flexion

Active muscle:

Rectus abdominus, Erector spinae, Internal and external obliques

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Movement and active muscle at the hip

Movement:

Flexion, Extention, Abduction and Adduction

Actice muscle:

Iliopsoas, Gluteus maximus, Medius, Minimus, Adductor longus, brevis and magnus

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Movement and active muscle at the Knee

Movement:

Flexion and Extention

Active muscle:

Rectus femoris,Vastus medialis, Intermedius, Lateralis, Biceps femoris, Semimembranosus and Semitendinosus.

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Movement and active muscle at the Ankle

Movement:

Dorsiflexion and Plantar flexion

Active muscle:

Tibialis anterior, Gastrocnemius and Soleus

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Agonist, Antagonist and Fixator

Agonist: This term discribes the muscle or muscles responsible for the movement. For example, when the knee flexes, the biceps femoris on the posterior side of the femur contracts.

Antagonist: This term describes the muscle or muscles that relax in response to the active muscle. For example, when the knee flexes, the rectus femoris on the superior side of the femur is relaxed and this allows the knee to go into flexion.

Fixator: This term describes the muscle or muscles that elp to stabilise a joint or joints. For example, while the biceps and rectus femoris are acting as agonists and antagonists the abdominal, oblique and spinae muscles act as fixators holding the body still while it works.

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The bicep curl

This is the first stage of a bicep curl when the dumb bell has been lowered

  • The agonist during the lowering phase is the bicep brachii
  • During this phase of movement, the muscle is getting longer even though it is contracting. This is known as an eccentric contraction
  • The opposing muscle that is relaxed is the tricep brachii
  • In the next stage of the bicep curl, when the dumb bell is being lifted, the same muscle, the bicep brachii, is responsible for this
  • The muscle is shortening as it is contracting, therefore it is a concentric contraction
  • The triceps brachii is relaxed and remains antagonist
  • Throughtout the exercise the shoulder remains still. The deltoid is therefore acting as a fixator as it is holding the humerus in position
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Slow and fast twitch muscle fibres

There are two main types of muscle fibres: slow twitch (SO) fibres (type 1) and fast twitch fibres (type 2). Fast twitch fibres are further broken down into fast oxidative glycolytic (FOG) fibres (type 2a) and fast twitch glycolytic (FG) fibres (type 2b)

Slow twitch refers to the contractile speed of the fibres that use aerobic enegry to power their movement. Fast twich glycolytic fibres use glycogen as their primary energy sources, working without oxygen. Fast oxidative glycolytic fibres (FOG) combine the structural properties of fast glycolytic fibres and slow oxidative fibres. However, they dont contract as quickly as fast glycolytic fibres or have as much endurance as slow twitch fibres.

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Muscle fibre types and physical activity

The way that out muscles are made up of different fibre types has a direct impact on the types of activity we can be good at. If we consider an athlete such as Usain Bolt, he is able to perform very quick contractions over a short period of time. He is likely to have muscles that are made up of large amounts of fast twitch glycolytic (type 2b) fibres. A centre court netball player may have a more balanced percentage of fibres. It is important to remember that whatever mix of muscle fibres we are born with we are able to train these to adapt either in size (hypertrophy) or quantity (hyperplasia)

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positive short term effects of exercise

  • Increased blood flow to your muscles. At rest, blood flow to muscles is approximatley 5% of the total available. However, during exercise this can rise to up to 90% of the blood flow available. Increased blood flow increases the oxygen and energy available to your muscles.
  • Muscles are very inefficient and much of the enegy we use to contract the is lost in heat. However, the increases in muscle temperature, between 1 and 2 degrees, enables your muscles to be more flexible and apply a greater force over a longer joint range.
  • Physical activity in the short term can increase your alertness as hormones are released. These hormones can also help you to feel more relaxed after the activity.
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Negative short term effects of exercise

  • increased chance of muscle soreness after participating in physical activity. However, repeated bouts of physical activity reduce this effect
  • High-intensity physical activity can leave you fatigued and after other sessions if not appropriately moderated.
  • energy stores and myoglbin levels withing the muscle can become depleated
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Positive long term effects of exercise

  • Increased thickness of each muscle fibre (hypertrophy) improving strengh and contractile speed.
  • increased number of muscle fibres (fibre hyperplasia), increased strengh of contraction and potentially increased neuron size
  • Increased availability of the fuel source required (CP, Glycogen and Triglycerides)
  • Slow twitch and FOG fibres develop bigger and more efficient capillary beds, increasing mitochondrial density
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Negative long term effects of exercise

  • Repeated bouts of physical activity without suitable rest periods can cause overuse injuries in muscles
  • Possible injuries such as fasciitis (inflamation of the sheath around the muscle) can occur, particularly in the tibialis anterior muscle
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warm ups and cool downs

A warm up increases the blood flow to muscles, improving oxygen, glycogen and triglyceride levels without depleting the muscle. Low-intensity exercise also increases the temperature of the muscles combined with passive and dynamic stretches reduces the risk of injury in the muscles 

A cool down maintains blood flow to the muscles after physical activity and provides the muscles with an opportunity to replenish levels of glycogen and creatine phosphate and refresh the levels of oxygen stored within the myoglobin

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