Key Muscle Groups

Label Your Body Pectoralis Major Quadriceps Deltoids Hamstrings Triceps Brachii Biceps Brachii Soleus Trapezius Rectus Abdominus Quadriceps Hamstrings Gastrocnemius Hip Adductors Tibialis Anterior Latissimus Dorsi External Obliques

Muscles

Skeletal Muscle These muscles are made up of cylindrical fibres and are under the control of the body. All these muscles are attached to the skeleton. These muscles make up about 40% of the weight of a man, but less for a woman because women have higher fat percentages. Muscles are made up of protein, when we are eating protein such as fish or meat we are actually eating the muscle of the animal.

Skeletal Muscle The skeletal muscles are usually long and thin and because they cannot push they are usually paired up with another skeletal muscle. One muscle contracts causing flexion at the joint, the other contracts extending the joint. These pairs of muscles are called antagonists. In order to get full movement while one muscle contracts the other must relax (isotonic contraction)

Slow Twitch Fast Twitch IIa Fast Twitch IIb Type 1 Fast Oxidative Glycolytic Fast Glycolytic Contract slowly Contract quicker Contract quickest Are moderately powerful Are quite powerful Are very powerful Are small Are bigger Are the biggest Have lots of mitochondria Have fewer mitochondria Have very few mitochondria High myoglobin content Moderate myoglobin content Low myoglobin content Resistant to fatigue Moderately resistent to fatigue Easily fatigued High capillary density Low capillary density High aerobic capacity / low anaerobic capacity Relatively high aerobic & anaerobic capacity. Low aerobic capacity / high anaerobic capacity Low muscle energy stores e.g. ATP, PC & muscle glycogen. higher muscle energy stores e.g. ATP, PC & muscle glycogen. The highest muscle energy stores e.g. ATP, PC & muscle glycogen.

Muscle Fibre Types The different amount of muscle fibre types in the body differ from person to person It is dependant upon the genes that have been passed through our families Proportions can vary according to the action of the particular muscle Muscle involved in maintaining posture are found to have large amounts of slow twitch fibres as they are continuously working to retain good posture.

Muscle Fibres and Training By structuring specific training activities an athlete can develop and bring about changes in skeletal fibres Suitable training can improve slow twitch fibres to operate more quickly However it is not possible to convert them to fast twitch fibres

Muscle Fibres and how they adapt to exercise. The right type of exercise will produce the appropriate response. So what is the right type of exercise? As a result of low intensity, long duration activities…Slow twitch fibres will become better able to produce energy aerobically, Type IIa fibres will start to take on type I characteristics and type IIb fibres will begin to become more aerobic efficient All 3 fibre types will become more efficient as a result of prolonged exposure to a particular environment. As a result of high intensity, short duration activities….Type IIb fibres will become better able to produce energy anaerobically, Type IIa fibres will begin to develop type IIb characteristics and Type I fibres will begin to become more anaerobically efficient As a result of high intensity, short duration activity that is repeated with little rest… Type IIa fibres will become better able to delay a lactic acid build up, Type I & type IIb fibres will take on type IIa characteristics.

Fibre Recruitment During exercise the body will use a combination of all 3 Fibre Types depending on exercise intensity Regardless of activity, always use type 1 first, then select either 2a or 2b depending on activity

Force Production Light Intensity Exercise – Mostly type 1 Medium Intensity Exercise – Type 1 & 2a High Intensity Exercise – Type 1, 2a & 2b