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Types of strength training
Weight training
Weight and resistance training are popular methods of strength training which
use gravity (through weight stacks, plates or dumbells) or elastic/hydraulic
resistance respectively to oppose muscle contraction. Each method provides a
different challenge to the muscle relating to the position where the resistance
to muscle contraction peaks. Weight training provides the majority of the
resistance at the initiating joint angle when the movement begins, when the
muscle must overcome the inertia of the weight's mass (however, if repetitions
are performed extremely slowly, inertia is never overcome and resistance remains
constant). In contrast, elastic resistance provides the greatest opposition to
contraction at the end of the movement when the material experiences the
greatest tension while hydraulic resistance varies depending on the speed of the
submerged limb, with greater resistance at higher speeds. In addition to the
equipment used, joint angles can alter the force output of the muscles due to
leverage and the relative overlap of actin and myosin contractile proteins.
Resistance training is a form of strength training in which each effort is
performed against a specific opposing force generated by resistance (i.e.
resistance to being pushed, squeezed, stretched or bent). Exercises are isotonic
if a body part is moving against the force. Exercises are isometric if a body
part is holding still against the force. Resistance exercise is used to develop
the strength and size of skeletal muscles. Properly performed, resistance
training can provide significant functional benefits and improvement in overall
health and well-being.
The goal of resistance training, according to the American Sports Medicine
Institute (ASMI), is to "gradually and progressively overload the
musculoskeletal system so it gets stronger." Research shows that regular
resistance training will strengthen and tone muscles and increase bone mass.
Isometric training
Isometric exercise or 'isometrics' are a type of strength training in which the
joint angle and muscle length do not change during contraction. Isometric
exercises are opposed by a force equal to the force output of the muscle and
there is no net movement. This mainly strengthens the muscle at the specific
joint angle at which the isometric exercise occurs, with some increases in
strength at joint angles up to 20° in either direction depending on the joint
trained. In comparison, isotonic exercises strengthen the muscle throughout the
entire range of motion of the exercise used.
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