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Strength
The capacity to exert a muscle contraction against resistance.
Types of contractions
Isotonic contractions
Isotonic contractions change the muscles in length. They can either be
concentric or eccentric.
Concentric – shorten muscles
Eccentric – lengthen muscles
Isometric contractions
This involves a static resistance during which the muscle does not change
length. E.g holding the leg in place.
How to improve strength
Progressive overload of frequency, intensity and duration.
Frequency – increase the number of repetitions or speed of a movement;
Intensity – add more resistance, as with weights
Durations – the length of time
Isometric contractions help increase strength but muscles will tire easily so
frequent rests will be needed.
Isotonic contractions are very effective to increase strength. Eccentric work
should be included if muscles are weak or injured, to increase flexibility.
Stamina
Staying Power. The endurance of muscles and/or the heart and breathing.
Muscle endurance
The power for a muscle to contract over time, as in strength (see progressive
overload).
Cardiovascular endurance
The heart, the blood and blood vessels, which transport necessary nutrients
and gases to and from the muscles and organs. The blood also carries heat to
the skin for removal by sweating and radiation and takes away waste
products.
What is the respiratory system? (see p32)
How to improve cardiovascular endurance
Aerobic exercise
Aerobic exercise improves long term endurance by increasing muscular
endurance/stamina, cardiorespiratory endurance/stamina, reduces fat
deposits and maintains bone mass.
Aerobic exercise uses oxygen and requires continuous, rhythmic use of large
muscle groups at 60-90% of maximum heart rate and 50-85% of maximum
oxygen uptake for 20-60 mins.
Anaerobic exercise
Anaerobic exercise works the muscles without oxygen and therefore is more
tiring and produces waste lactic acid.