A+P - muscular system.

• B1.

  • There are over 640 muscles in the human body and these make up approximately 40% of your body mass​.
  • The muscles that move your bones during sporting movements are called skeletal muscle.
  • You will learn all about these muscles, their fibres and the actions they cause- as well as the way in which they respond and adapt to exercise​.
• B1.

  Skeletal Muscle.

  • Also known as striated or striped muscle due to it’s appearance​.
  • Voluntary muscle which means it is under conscious control​.
  • Critical to sport and exercise as they are connected to the skeletal system​.
  • Skeletal muscle contracts and as a result, pulls on bones to create movement​.
  • They can become fatigued during exercise​.
• B1.

  Cardiac Muscle.

  • Only found in the wall of the heart​
  • Works continuously and doesn’t fatigue (when exercising)​
  • Specialist striated tissue that has its own blood supply​
  • Involuntary contractions help to force blood through blood vessels and around the body​
• B1.

  Smooth Muscle.

  • Involuntary muscle, works without conscious thought- slow contractions​
  • Functions under the control of the nervous system​
  • Located in the walls of your digestive system (regulates digestion) and blood vessels (regulates blood pressure)​
• B2.

  • Skeletal muscles are voluntary muscles which means they are under your control​
  • For example, you must send a conscious signal from your brain to your muscles to perform a sporting action​
  • Skeletal muscles are attached to your skeleton via tendons which pull on specific bones when the muscle contracts​
  • Skeletal muscles not only provide you with movement, strength and power but they are responsible for maintaining posture and generating heat ​
• B2.

  Major Muscles.

  • Deltoids​
  • Biceps​
  • Triceps​
  • Wrist Flexors​
  • Wrist Extensors​
  • Supinators​
  • Pronators​
  • Pectorals​
  • Abdominals​
  • Obliques​
  • Quadriceps​
  • Hip Flexors​
  • Tibialis Anterior​
  • Erector Spinae ​
  • Trapezius​
  • Latissimus Dorsi​
  • Gluteals​
  • Hamstrings​
  • Gastrocnemius​
  • Soleus​
• B3.

  Antagonistic muscles.

  • Under normal circumstances the muscles are partially contracting, ready to react to a stimulus from your nervous system
• B3.

  Antagonistic Muscle Pairs.

  • When a muscle contracts, it exerts a pulling force on the bones to which it is attached, causing them to move together around the joint​
  • Muscles must cross the joints that they move​
  • If a muscle did not cross a joint, no movement could occur​
• B3.

  Antagonistic Muscle Pairs - Muscle Action.

  • Stimulus: A stimulus from the nervous system occurs​
  • All or nothing​: Muscle fibres work on an all or nothing basis- either contracting completely or not at all​
  • Muscle contraction: At the point of contraction your muscles shorten and pull on the bones to which they are attached
• B3.

  Antagonistic Muscle Pairs.

  • When a muscle contracts , one end normally remains stationary while the other end is drawn towards it​
  • The end that remains stationary is known as the origin and the end that moves is called the insertion​
• B3.

  Antagonistic Muscle Pairs.

  • Muscles do not work in isolation​
  • They are assembled in groups and work together to bring about movement​
  • They act only by contracting and pulling​
  • They do not push, although they are able to contract without shortening and hold a joint firm and fixed in a certain position​
  • When the contraction ends, the muscles become soft but do not lengthen until stretched by the contraction of the opposing muscles​
• B3.

  Antagonistic Muscle Pairs.

  • The muscle that shortens to move a joint is called the agonist or prime mover​
  • This is the muscle principally responsible for the movement taking place- the contracting muscle​
  • The muscle that relaxed in opposition to the agonist is called the antagonist​
  • This is the muscle that is responsible for the opposite movement and the one that relaxes as the agonist works​
  • If it did not relax the movement would not take place.​
  • Antagonists exert a ‘braking control’ over the movement​
• B3.

  Synergists.

  • These are muscles that work together to enable the agonists to operate more effectively​
  • They work with agonists to control and direct movement by modifying or altering the direction of pull on the agonist to the most advantageous position.​
• B3.

  Fixators.

  • Fixator muscles stop any unwanted movement throughout the whole body by fixing or stabilising joint or joints involved in movement​
  • Fixator muscles stabilise the origin so that the agonist can achieve maximum and effective contraction​
  • Fixator muscles, contract isometrically (without movement)​
  • They help to prevent injuries​
• B3.

  Common Sporting Movement and Antagonistic Muscle Pairs.

  • Bicep Curl​
  • Antagonistic Muscle Pair- Biceps and triceps​
  • Upwards Phase- The bicep is the agonist, as it contracts, to flex the elbow and lift the weight upwards. The triceps are the antagonist, as they relax to allow the contraction of the bicep​
  • Downwards Phase- The triceps is the agonist, as it contracts, to extend the elbow and lower the weight downwards. The biceps are the antagonist, as they relax to allow the contraction of the triceps.​
• B3.

  Common sporting Movements and Antagonistic Muscle Pairs.

  • Squat, kicking a ball, any movement with a bend at the knee​
  • Antagonistic Muscle Pair- Quadriceps and Hamstrings
  • Downwards Phase- The hamstrings is the agonist, as it contracts to flex the knee. The quadriceps are the antagonist as they relax to allow the contraction of the hamstrings.​
  • Upwards Phase- The quadriceps is the agonist, as it contracts to extend the knee. The hamstrings are the antagonist as they relax to allow the contraction of the hamstrings.​
• B3.

  Common Sporting Movement and Antagonistic Muscle Pairs.

  • Sit up​
  • Antagonistic Muscle Pair- Erector Spinae and Abdominals​
  • Upwards Phase- The abdominals are the agonist, they contract to cause flexion at the trunk/hips. The erector spinae is the antagonist, as this relaxes to allow the abdominals to contract​
  • Downwards Phase- The erector spinae, is the agonist, it contracts to cause extension of the trunk/hips. The abdominals is the antagonist, as they relax to allow the erector spinae to contract.​
• B3.

  Common Sporting Movement and Antagonistic Muscle Pairs.

  • Press Up​
  • Antagonist Muscle Pair: Pectorals and trapezius​
  • Downwards Phase: Pectorals are the agonist, the triceps are also the agonist- the agonist eccentrically contract (meaning they get longer). The trapezius and biceps are the antagonists- and they contract concentrically. The deltoids are the synergists and contract eccentrically. The abdominals, obliques and quadriceps are the fixator muscles and all contract isometrically.​
• B3.

  Common Sporting Movement and Antagonistic Muscle Pairs.

  • Press up.
  • Antagonist Muscle Pair: Pectorals and Trapezius.
  • Upwards Phase: Pectorals are the agonist, the triceps are also the agonist-the agonist concentrically contract (meaning they get shorter). The trapezius and biceps are the antagonists- and they contract eccentrically. Synergists, deltoids, support the agonists in this movement by concentrically contracting. Fixators, abdominals, obliques and quadriceps, prevent any unwanted movement and all contract isometrically​
• B4.

  Skeletal Muscle Contraction.

  Isometric.

  • During an isometric contraction the length of the muscle does not change and the angle of the joint does not alter​
  • However, the muscle is actively engaged in holding a static position​
  • An example of this is the abdominal plank position​
  • This type of muscle work is easy to undertake but rapidly leads to fatigue​
  • It can cause sharp increases in blood pressure as blood flow is reduced​
  • Examples are the biceps in the cross position on the rings or the abs when doing the plank.
• B4.

  Skeletal Muscle Contraction.

  Eccentric.

  • An eccentric muscular contraction is when a muscle returns to its normal length after shortening against resistance​
  • Again, using a bicep curl as an example, this is the controlled lowering of your arm to its starting position​
  • At this point your muscles are working against gravity and act like a braking mechanism​
  • This contraction can be easier to perform, but it does produce muscle soreness​
• B4.

  Skeletal Muscle Contraction.

  Eccentric.

  • Eccentric muscle contractions occur in many sporting and daily activities​
  • Walking downstairs and running downhill involve eccentric contraction of your quadriceps which are used to control the movement​
  • Eccentric contraction can be a significant factor in the stimulus that promotes gain in muscle size and strength​
  • Eccentric contractions are sometimes known as the negative phase of muscle contraction​
• B4.

  Skeletal Muscle Contraction.

  Concentric.

  • When you make any movement such as a bicep curl, your muscle will shorten as the     muscle fibres contract​
  • In the bicep curl, the biceps shorten, bringing the forearm towards the upper arm​
  • Concentric contractions are sometimes known as the positive phase of muscle contraction​
• B4.

  Remembering Muscle Contractions.

  • Concentric- Contraction​
  • Muscle contracts, gets smaller, positive phase (e.g. upwards phase of bicep curl)​
  • Eccentric- Elongate​
  • Muscle returns to normal length, gets longer, negative phase (e.g. downwards phase of bicep curl)​
  • Isometric- No Movement​
  • Muscle contracts but no movement in length or position, holding​
• B5.

  Muscle Fibres.

  • All skeletal muscles are made up from muscle fibres​
  • These fibres fall into two main categories depending on their speed of contraction; Type I (slow twitch) and Type IIa and IIx (fast twitch)​
  • The mix of fibres varies from individual to individual and within the individual from muscle group to muscle group​
  • To a large extent this fibre mix is inherited​
  • However, training can influence the efficiency of the different fibre types ​
• B5.

  Muscle Fibres.

  Type 1.

  • These contract slowly and with less force​
  • They are slow to fatigue so are suited to longer-duration aerobic exercises- such as?​
  • Aerobic activity describes exercises where energy is produced using oxygen​
  • Slow twitch fibres have a rich blood supply and contain many mitochondria to sustain aerobic metabolism​
  • Type 1 fibres have a high capacity for aerobic respiration​
  • They are recruited for lower intensity, longer duration activities​
• B5.

  Muscle Fibres.

  Type 11a.

  • Type IIa, also known as fast twitch or fast-oxidative fibres are fast-contracting, able to produce a great force and are also resistant to fatigue​
  • These fibres are less reliant on oxygen for energy supplied by the blood and therefore fatigue faster than slow-twitch fibres​
  • Type IIa fibres are suited to speed, power and strength activities such as weight training with repeated repetitions (10-12 reps) and fast running events such as the 400 metres​
• B5.

  Muscle Fibres.

  Type 11x.

  • Type IIx fibres, also called fast twitch or fast glycolytic fibres, contract rapidly and have the capacity to produce large amounts of force, but they fatigue more readily, making them better suited to anaerobic activity​
  • They depend almost entirely on anaerobic respiration and are recruited for higher intensity, shorter-duration activities​
  • They are important in sports that include many stop-go or change of pace activities such as rugby or football, as well as 100m sprinters​
• B5.

  All or None Law.

  • For a muscle to contract it must receive a nerve impulse, and this stimulus must be sufficient to activate at least one motor unit which contains the motor neuron (nerve cell) and the attached muscle fibres​
  • Once activated, all the muscles fibres within ​

      the motor unit will contract and produce a ​

      muscle twitch​

  • This is known as the ‘all or none’ law, as muscle​

      fibres either respond completely (all) or not at all ​

      (none)​
• B6.

  Responses of the Muscular System to a Single Sport/Activity.

  • When you exercise or take part in sport your muscles will respond in a variety of ways​
  • Some of these responses are immediate and are known as acute responses​
  • Responses that take place over a longer period of time are known as chronic responses​
• B6.

  Acute Responses.

  • Increased blood supply​
  • Increased muscle temperature​
  • Increases muscle pliability​
  • Lactate​
  • Micro-tears​
  • Delayed onset of muscle soreness​
• B6.

  Acute Responses.

  Increased Blood Supply.

  • When you exercise there is an increase in metabolic activity (the rate at which you produce and release energy)​
  • An increase in metabolic activity requires a greater amount of oxygen and glucose in the muscles- this demand is met by the blood​

  How does this happen?​

  • Blood vessels expand and get wider allowing more blood to get to the muscle- vasodilation​
  • Blood flow therefore increases which will provide more oxygen to the muscles, it will also remove waste products such as carbon dioxide​
• B6.

  Acute Responses.

  Increased Muscle Temperature.

  • When you exercise you get warmer- this is because your muscles need energy from fuels such as carbohydrates and fats​
  • Fats and carbohydrates are broken down in a chemical reaction, and heat is the waste product​
  • The more you exercise, the harder you train, the more energy your muscles need- this results in more heat being produced ​
  • When you warm up before exercise you are preparing your muscles for exercise by slowly increasing their temperature​
• B6.

  Acute Responses.

  Increased Muscle Pliability.

  • The warming of your muscles during activity makes them more pliable and flexible​
  • Pliable muscles are less likely to suffer from injuries such as muscle strains​
  • An increase in pliability will improve joint flexibility, as warm and pliable muscles are able to stretch further​
• B6.

  Acute Responses.

  Lactate.

  • When performing high intensity activity you may experience a burning sensation- this is caused by lactic acid​
  • Lactic acid is formed as a waste product of anaerobic respiration​
  • This build up of lactic acid can cause rapid fatigue and may impede muscular contractions if it is not removed quickly​
• B6.

  Acute Responses.

  Micro Tears.

  • During resistance training such as weight training, your muscles are put under stress to the point that tiny tears occur in the muscles​
  • These micro tears cause swelling in the muscle which puts pressure on the nerve endings and creates pain ​
  • Training improvements will only be made if the body has rest and time to repair these micro tears, making the muscle a little bit stronger than it was before​
  • Proteins are used to repair muscle tissue​
• B6.

  Acute Responses.

  Delayed Onset of Muscle Soreness.

  • DOMS is the pain felt 24-48 hours after taking part in strenuous physical activity​
  • The soreness can usually last up to 3 days ​
  • DOMS is caused by micro tears that occur when you exercise, particularly if you are unaccustomed to the intensity of exercise​
  • DOMS is often associated with exercises where eccentric muscle contraction has occurred​
• B7.

  Adaptations of the Muscular System to Exercise.

  • Training or exercising regularly over a long period of time will allow your body’s muscular system to change and adapt​
  • These are known as chronic responses​
• B7.

  Chronic Responses.

  • Hypertrophy.
  • Increased tolerance to lactate.
  • Increased tendon strength.
  • Increased size and number of mitochondria.
  • Increased myoglobin store.
  • Increased storage of glycogen.
  • Increased storage of fat.
• B7.

  Chronic Responses.

  Hypertrophy.

  • Regular resistance training where the muscles are overloaded will increase muscle size and strength​
  • The increase in muscle size is a result of the muscle fibres becoming larger due to increases in protein in the muscle cells; this is known as hypertrophy​
  • The muscle fibres increase in size over time so that they can contract with greater force​