SEHS Topic 4.2.2- 4.2.5 Joint and
Movement Type
Outline the types of different muscle
contractions
• Types: isotonic, isometric, isokinetic, concentric,
eccentric
• An isotonic contraction is any contraction is which a
muscle shortens to overcome resistance.
• When a muscle shortens, at least one joint moves,
and body movement occurs. The resistance can
come from lifting a weight, pulling up your body, or
from some other object such as when you lift a bag
of groceries.
• An isotonic contraction involves two
phases.
• The concentric phase occurs when
muscle is shortened in an upward
movement.
• The eccentric phase occurs when the
muscle is lengthened in a downward
movement.
• 1. A concentric muscle contraction is a type of
muscle activation that increases tension on a
muscle as it shortens.
• Concentric contractions are the most
common types of muscle activation athletes
perform in a gym when lifting weights
Muscle Contraction Types Cont’d:
Eccentric
• An eccentric muscle contraction is a type of
muscle activation that increases tension on a
muscle as it lengthens. Eccentric contractions
typically occur when a muscle opposes a
stronger force, which causes the muscle to
lengthen as it contracts.
• Common exercises that cause an eccentric
contraction include lowering weights and the
downward motion of squats, going down
stairs, running downhill, push ups or pull ups.
Isometric Contraction
• Isometric muscle contractions do not involve
any movement. An isometric contraction
occurs when your muscles push against a
fixed resistance and no joint or body
movement occurs. Even though there is no
movement, your muscles are still working
and contracting.
Cont’d
• Isometric Examples
• You can do isometric exercises in two different ways:
By trying to move something that is too heavy for you
to move or by holding static exercise poses. The
second method includes plank holds, squat holds, side
planks, abdominal holds, lunge holds and any other
motionless exercise. Rather than counting repetitions,
isometric exercises involve holding the position for a
given amount of time, such as 30 seconds.
• Isometric exercises do not significantly build
strength but they can maintain strength, which is
why they are sometimes used in a rehabilitative
setting.
• Ex. If someone suffers from arthritis and it is
painful to perform range of motion exercises,
isometric exercises may help maintain strength in
the joint muscles without causing more pain
Isokinetic Contraction
• An isokinetic contraction is a specific type of
concentric muscle contraction that occurs when
the muscle contracts and shortens at the same
speed throughout the entire range of motion.
• To produce one, special equipment is usually
needed to gauge the speed of the contraction and
keep it steady regardless of the force being
exerted.
• This allows the muscle to maintain maximum force
throughout the entire movement.
Cont’d
• Isokinetic exercises are also used in therapeutic settings.
• Using a dynamometer to control the contraction, isokinetic
exercise helps build strength in stroke victims or people who
have limited used of their muscles. An isokinetic contraction
is a dynamic contraction but the speed of the entire
movement is controlled by the machine.
• This control prevents injury and also measures areas of
strength and weakness in muscles.
• Any exercise involving the contraction of muscles can be
isokinetic if the dynamometer is being used
What is a dynamometer?
• A dynamometer or "dyno" for short, is a device for
measuring force, torque, or power.
• In the medical terminology, hand-held
dynamometers are used for routine screening of
grip and hand strength, and the initial and ongoing
evaluation of patients with hand trauma or
dysfunction.
• They are also used to measure grip strength in
patients where compromise of the cervical nerve
roots or peripheral nerves is suspected
Cont’d
Agonistic and Antagonistic Muscles
• Most muscles work in pairs, and when a muscle
works it needs to have an agonist and an
antagonist.
• Antagonistic pairs are located in opposite sides of
a joint or bone.
• An "antagonist" is a classification used to
describe a muscle that acts in opposition to the
specific movement generated by the agonist and
is responsible for returning a limb to its initial
position
Cont’d
Explain the concept of reciprocal inhibition
• When the central nervous system sends a message
to the agonist muscle (muscle causing movement)
to contract, the tension in the antagonist muscle
(muscle opposing movement) is inhibited by
impulses from motor neurons, and thus must
simultaneously relax.
Analyze movements in relation to joint
action and muscle contraction
• Ex. During the upward movementr of a bicep
curl the joint action is: ____________
• Ans.: Flexion
• While the biceps contracts concentrically, the
tricep contracts eccentrically.
• Analyze the exercises on the following slide for
both.
• 1.
2.
• 3.
4.
Explain delayed onset muscle soreness (DOMS) in relation to
concentric and eccentric muscle contraction
Cont’d
• DOMS is primarily a function of eccentric muscle
contractions.
• It is associated with muscle damage on a structural
level (microtears) and the inflammation response
that follows.