Transcript physiology - Cert IV Fitness PT Loftus

Sutherland College Health & Recreation Semester 2 2012. Version 1
CIV Fitness/S&C
Steven Tikkanen – F129
1
ESSENTIALS OF STRENGTH TRAINING AND CONDITIONING
CHAPTERS 1 & 2
MUSCLE PHYSIOLOGY &
NEUROMUSCULAR ANATOMY AND
ADAPTATIONS TO CONDITIONING
FIBRE TYPES
• Type I (or slow twitch)
• Type II (or fast twitch)
• Type I
• Resist fatigue by having large numbers of mitochondria
• High aerobic enzyme activity
• Dense capillary concentration
FIBRE TYPES
• Type II
• Type IIb
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•
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Muscle fibre fatigues rapidly
Relatively few mitochondria
Low aerobic enzyme activity
Few capillaries
• Type IIa
• Has some of the fatigue-resistant qualities of Type I muscle
fibres
• More mitochondria
• Greater aerobic enzyme activity
• Greater capillary density
• Compared to Type IIb muscle fibres
TYPES OF MUSCLE ACTION
• Concentric muscle actions
• Occur when the total tension developed in all cross-bridges of a
muscle is sufficient to overcome any resistance to shortening.
• Isometric muscle actions
• Occur when the tension in the cross-bridges equals the resistance
to shortening.
• The muscle length remains relatively constant.
TYPES OF MUSCLE ACTION
• Eccentric muscle actions
• Occur when the tension developed in the cross-bridges is less
than the external resistance
• The muscle lengthens despite contact between the myosin crossbridge heads and the actin filaments
ACTIVATION OF MUSCLES
• Motor unit
• Is a motor neuron and all of the muscle fibres that it innervates.
• This is the basic functional entity of muscular activity.
ACTIVATION OF MUSCLES
• Acetylcholine
• Is the neurotransmitter released at the pre-synaptic terminal that
causes excitation of the sarcolemma.
• Not the action potential (electric current)
NEUROMUSCULAR ANATOMY AND
ADAPTATIONS TO CONDITIONING
Neuromuscular anatomy and physiology
• All-or-none principle – same as firing a gun. Once a
sufficient amount of pressure is placed on the trigger, the
gun fires; however, squeezing the trigger harder will not
cause the bullet to go faster.
• A stronger stimulus does not cause a stronger contraction.
• Twitch – is an action potential travelling along a motor
neuron results in a short period of activation of the
muscle fibres within the motor unit.
NEUROMUSCULAR ANATOMY AND
ADAPTATIONS TO CONDITIONING
• Recruitment
• If the activity requires near-maximal performance, such as a
power clean.
• Most motor units are called into play.
• With Type IIb making the more significant contribution.
• Complete activation of the available motor neuron pool is
probably not possible in un-trained people.
NEUROMUSCULAR ANATOMY AND
ADAPTATIONS TO CONDITIONING
Proprioception
• Proprioceptors – are located in joints, muscles
and tendons.
• Kinaesthetic sense – is the information sent to
the brain consciously or unconsciously by the
proprioceptors, to give conscious appreciation of
the body in three-dimensional space.
• Muscle spindles – intrafusal fibre sense stretch
and send information to CNS, the motor neuron
sends information back for the extrafusal fibres
to contract, to take away the stretch. Knee jerk
test.
NEUROMUSCULAR ANATOMY AND
ADAPTATIONS TO CONDITIONING
• Golgi tendon organs – GTO feels stretch if the
stretch is to great then the GTO will switch off
the muscle under stretch.
Neuromuscular adaptations to exercise
• Hypertrophy – increase in muscle cross sectional
area (CSA). It has been found that fast twitch
muscles increase in size much more than slow
twitch muscles. Therefore it has been suggested
that fast twitch athletes will have a greater CSA.
NEUROMUSCULAR ANATOMY AND
ADAPTATIONS TO CONDITIONING
• Hypertrophy – cont. –
• Time – it can take up to 6-8 weeks to see any hypertrophy in
muscle. As the first few weeks strength will come from neural
adaptations. Both intramuscular and intermuscular
coordination improves. Therefore less muscle is needed to
perform work, therefore must increase intensity.
AEROBIC ENDURANCE TRAINING
• Aerobic endurance training increases aerobic power, it does
not enhance muscle strength or size.
• In fact, intense aerobic endurance training can actually
compromise the benefits of resistance training.