Isometric, Isotonic, and Isokinetic Exercises

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Isometric Exercise

Same length; Muscle contraction without noticeable change in length of muscle (velocity = 0); No physical work done, but tension and force output production are high; Contraction must be held for at least 6 seconds to develop peak tension

Types of Isometrics

Muscle setting, Resisted isometrics, Stabilization exercises

Muscle Setting

Low intensity against little or not resistance; Promote muscle relaxation, mobility and circulation while decreasing pain and spasm; Does not approve muscle strength but can slow muscle atrophy

Resisted Isometrics

Performed against manual or mechanical resistance; Develop strength when pain or movement limitations exist; For strength gains, use force 60-80% of muscle's max force capacity; Amount or resistance the muscle can hold will vary based on the point in the ROM at which the exercise is completed; In order to gain strength throughout the range, isometric exercises should be performed at various positions throughout the range

Stabilization Exericses

Co-contraction of msucles surrounding a proximal joint; Isometric contraction held at mid-range against gravity; Usually performed in weight bearing positions as close-chain exercises; Body weight of patient is usally the resistance provided for exercises; Rhythmic stabilization (applying resistance manually to the same joint in opposite motions to facilitate a simultaneous contraction of muscles on both sides of the joing

Precaution

Be careful to avoid Valsalva maneuver (perform rhythmic breathing)

Isometric Exercise Positives

Can use initially in rehab secondary to ROM; Maintain neural connections

Isometric Exercise Negatives

Doesn't strengthen full ROM (10 degress carryover); No functional benefits

Isometric Exercise Examples

Quad sets/ham sets; Wall push-ups; Gluteus squeezes; Ball squeezes between legs

Isotonic Exercise

Same tension; Exercise carried out against a load (constant or vaiable) while the muscle shortens or elongates through the available range (velocity = variable); Used to increase dynamic strength, muscle endurance and power; May be performed with manual or mechanical resistance

Isotonic Constant vs. Variable Load

We typically think of isotonic exercise having a fixed load. However, since force production is not the same throughout the muscle with a fixed load, a variable load can be defined as isotonic. Key Point: Load cannot be greater than what the weakest point of the muscle can lift; Variable loads allow the resistance to change throughout the full ROM in order to provide load on the muscle at multiple pints throughout the ROM

Isotonic Concentric vs. Eccentric

Should usally include a omponent of each; this most resembles functional use of muscles; Concentric; Eccentric

Isotonic Concentric

Tension develops as muscle is shortened when external force is applied

Isotonice Eccentric

Tension Develops as muscle is elongated when external force is applied; Provide shock absorption during closed-chain activites; Greater force production capabilities than concentric contraction; More efficient than concentric contraction (less effort required); May be easier to perform in acute phases of rehab than concentric exercies; Control greatest load-->maximal resistance can be used in later stages of rehab; Greater resistance to fatigue by consuming less oxygen and fewer energy stores

Isotonic Precautions

Increased stress on cardiovascular system (should teach thrymic breathing); DOMS (keep load low acutely and progressively increases)

Isotonic Force Production Variations

Max eccectric contaction produces greater force than max concentric contraction; The same force production for concentric contraction requires a greater number of motor units be recruited

Isotonic Velocity alters production of force via neuromuscular unit capacity

Slow Velocity; Higher velocity; For strength training, slow speed is utilized with heavy loads

Slow Velocity

Greater force with eccentric contraction

Higher Velocity

Eccentric contraction levels off or lsightly increases while concentric contraction decreases

Isotonic Positives

Multiple points get load; Can be open or closed chain; Easy application; Can be inexpensive; Contraction against a maximal load produces more tension than an isometric contraction

Isotonic Negatives

Only can use oad the weakest point can lift; Requires training on proper completion for safety

Isotonic Concentric Examples

Lifting weights, push-ups (lowering phase), theraband

Isotonic Eccentric Examples

Lowering weights, releasing theraband, slow stand/lowering to sit

Open Kinematic Chain

Exercise is when the distal end of the moving segment moves freely

Open Kinematic Chain Exercise

Can be performed with manual or mechanical resistance, dynamically or statically; If weight bearing is contraindicated, this will be the only type of exercise; Don't prepare patient for funtional performance of skills if not used in combination with close-chain, weight-bearing exercises

Open-Chain Kinematic Positives

Allow isolation of one joint or muscle; Can get infor about torque production with isokinetics; Decreased resitance forces

Open-Chain Kinematic Negatives

Don't help joint position sense or proprioception; Increased acceleration and joint deformation; Increased mechanoreceptor deformation

Open-Chain Kinematic Examples

SAQ/LAQ; Ankle circles; Heel slides/ abduction slides

Closed-Chain

Exercise is when the body moves over a fixed distal segment

Closed-Chain Exercise

Can be performed with manual or mechanical resistance, using the patient's body weight, and in a dynamic and static fashion; Involve concentric, eccentric and isometric contractions; Provide load for muscles, joints, bones and noncontractile tissues; Stimulate mechanoreceptors within joints-->co-contraction-->increased stability; Improve muscle power/strength/endurance, stability, balance, and coordination; Can't be performed if NWB; Goor for improving stability in shoulder and hip girdles

Closed-Chain Positives

Teach agonist/antagonist relationships; Can be multiplaner; Force begins at the ground; Each joint absorbs some of the force; Decreased shearing forces; Decreased acceleration forces; Increased joint congruency; FUNCTIONAL!!!

Closed-Chain Negatives

Too much strain for patients with RA; Difficult to see muscle compensations

Closed-Chain Examples

Weight shifting, wall push-ups, lifting weights, standing activities

Isokinetic Exercise

Same movement speed; Movement occurring at a constant, controlled speed (velocity=constant); Resistance will vary throughout the RAM, as exercise load changes in relation to the ability of the muscle to produce force in various parts of the ROM; Allow concentric and eccentric exercise; Strength gains appear to be speed dependent: training speed=speed where the strength gains occur; Can safely perform movements at high rate that would cause damage in isontonic exercises

Isokinetic Concentric

Capacity of muscle to produce force decreases as speed increases

Isokinetic Eccentric

Capacity to produce force may increase to a point as speed increases

Isokinetic Positives

Maximum resistance through full ROM: can change at weaker points in ROM; High speed (500 degrees/sec); Provides good objective data (work comp)

Isokinetic Negatives

Expensive equipment; No interia; Requires training of staff

Isokinetic Examples

Cybex; Kincom; Cam and pulley system; Athletic Rehab

Isotonic Equipment

Free weights; Elastic resistance devices; Pulley systems; Trampoline; Variable-resistance equipment; Swiss ball; Body blade; Exercise bike; Resistive reciprocal exercise unit; Closed-chain resistance devices

Isomentric Equipment

Use isotonic equipment to hold weight that is too heavy for patient to life; Isokinetics set at 0 degrees/sec

Isokinetic Equipment

KIN/COM. Biodex, Lido, Merac, Cybex II, UBE, Orthotron II

Isometric Regimens

Breif repetitive; Multiple-angle

Breif Repetitive

Hold isometric contraction for 6 seconds; 20 second between contractions; Up to 20 contractions can be performed

Multiple-Angle

Used to achieve increased strength throughout ROM, as physiological overflow occurs only in 20 degrees surrounding training angle; Resistance should be applied at last every 20 degrees to strengthen entire ROM; One regimen has 10 reps, 10 bouts, 10 second contraction every 10 degrees

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