Active Resisted Exercise-part 1

Mazyad Alotaibi

Introduction Introduction • Resistance exercise is an essential element of Rehab

programs for person with impaired function and for those who wish to promote and maintain health and physical well-being.

• It can be defined as any form of active exercise in which a dynamic or static muscle contraction is overloaded (resisted) by an external force (manually or mechanically). The resistance must be sufficient to increase the intra-muscular tension to the maximum without interfering with the ability of the muscle to do coordinated movements.

A comprehensive examination and evaluation is the basis upon which a program of resisted exercise is warranted and will improve a person's current level of function.

Factors affect the appropriate resistance training:

1- Underlying pathology.2- Extent and severity of impairment.3- The presence of other deficits.4- The stage of tissue healing after injury of surgery.5- Patient's age6- Overall level of fitness.7- Cooperation of the patient with the program.

Forms of resistance:• Free weights (dumbbells, weight machines).

• Pulley circuit• Springs• Water• The patient• The physiotherapist • Strong elastic bands, and even the body itself.

N.B. In resistance training, intensity is determined by the amount of weight against which subjects are working. It is very important to start at a low level to avoid injury

Types of Resistance Exercise• Isometric resistance exercise: In which a muscle contracts without change in length or visible

motion.• Dynamic (Isotonic) exercise: In which a muscle contracts against load which may be- Manual: in which the resistance force is applied by the therapist- Mechanical: in which the resistance force is applied by

mechanical equipment.• Isokinetic exercise: In which the velocity of muscle contraction is controlled by a

rate-limiting device that controls the speed of movement of a body part.

I. Isometric (Static) Exercise- Is static form of exercise during which muscle contracts and produces

tension without change in the length of the muscle or visible joint motion.

- During isometric contraction a great amount of tension and force output produced from the muscle, which will increase strength if it is sustained against resistance for at least 6 seconds.

- Capable of increasing muscle strength at specific joint angles- May produce spikes in systolic blood pressure

• Could cause life-threatening cardiovascular accident• To reduce this event to occur - REMIND the person to breath.

• Widely used in rehabilitation• Attempt to use positional or functional exercise – work at multiple

angles throughout the range if possible

• Contractions should be held for 10 seconds at frequency of 10 or more per hour

– Utilized to enhance lift or activity at “sticking point”

Types of Isometric (Static) Exercise :1- Muscle-setting exercises: low –intensity, isometric exercises performed against little to no resistance. It will not improve strength but retard muscle atrophy in early stage of rehabilitation. Quadriceps and Gluteal muscles are common examples for Muscle-setting exercises.

2- Resisted isometric exercise: isometric exercises performed against manual or mechanical resistance to increase strength when active movement is painful. - The amount of tension produced during isometric exercise, is directly affected by the length of muscle at the time of contraction. Therefore, the amount of resistance also must be vary at different angles in the range.

3- Stabilization exercise: joint or postural stability can be developed by isometric exercise through activating co-contraction, that is, the contraction of antagonist muscles that surround proximal joints. Co-contraction is achieved by mid-range isometric holding against manual resistance or against gravity, in which emphasis is placed on isometrically controlling trunk musculature and proximal muscle of the extremities.4- Multiple-angle isometric exercise: in which the resistance ( manual, mechanical), is applied at multiple joint positions within the available ROM.

II. Dynamic Exercise• When a muscle contracts dynamically against a fixed resistance, the tension produced

from the muscle varies as the muscle contracts and shortens (concentric) or lengthens under tension (eccentric).

Types of Dynamic ExerciseTypes of Dynamic Exercise

1- Manual or mechanical resistance: the Dynamic Exercises are performed against manual or mechanical resistance.

2- Concentric and Eccentric exercise: in which the resistance is applied to a muscle as it shortens or lengthens.

■Concentric exercise involves dynamic resistance of a muscle while muscle shortening occurs as in lifting a weight.

■ Eccentric exercise involves dynamic resistance of a muscle while muscle lengthening occurs in an attempts to control the resistance. It involves negative work as in lowering a weight, descending stairs and provide a source of shock absorption during closed-chain functional activities.

■ Eccentric contraction produces more tension than an isometric or concentric contraction.

■ Eccentric contraction consumes less oxygen, fewer energy stores, fewer motor units fire to control the same load than concentrically.

■ Concentric muscle contractions accelerate body segment, while while eccentric muscle contraction decelerate body segment.

3-Open and Closed Kinematic chains exercises: they were used to describe how forces occur during human motion and how segments of the body are linked together.Open Kinematic chain exercise refers to movement in which the distal segment (the foot or hand) moves freely in space.- Traditionally most manual and mechanical resistance exercise have been applied using Open Kinematic chain exercise.- Open Kinematic chain exercise can be used if weight bearing is contraindicated. - Also Open Kinematic chain exercise can be performed in a dynamic or static manner. Closed Kinematic chain exercise refers to movement where the body moves over a fixed distal segment.- Closed-chain exercise are performed in a weight-bearing position when the foot is planted on the ground and the muscle action lifts or lowers the body as in stair climbing or squatting activities.- Closed-chain exercise occurs in upper limb when a person performs a push-up.- Closed-chain exercise are used to stimulate mechanoreceptors in and around joints more effectively than open-chain exercise.- Closed-chain activities improve stability, balance, coordination and agility in functional weight-bearing posture.

III. Isokinetic Exercise- Is a form of dynamic exercise in which the velocity of muscle shortening or lengthening is controlled by a rate-limiting device that control the speed of movement.- The resistance met during Isokinetic Exercise accommodate to the tension-producing capabilities of the muscle and loads the muscle to capacity throughout the ROM, and that is why called accommodation resistance exercise.accommodation resistance exercise.- Isokinetic training can occur in either concentric or eccentric mode.- Speeds of exercise may range from a slow velocity (15-30o/ sec) to a very fast velocity (300-400o/ sec). - Isokinetic training can be used safely to increase muscle strength, endurance and power.

Uses and indicationsThe main purposes of resistance exercise is to

improve muscle performance which refers to, the capacity of a muscle to do work (force x distance), this muscle performance can be enhanced by some form of resisted exercise.

Elements of muscle performance:1- Strength: the greatest measurable muscle

tension exerted by a muscle or muscle group to overcome resistance during a single, maximum effort.

In order to increase the strength of a muscle, muscle contraction should be loaded for a relatively low number of repetition or over a short period of time.

2- Endurance: the ability to perform low-intensity, repetitive, or sustained activities over an extended period of time without fatigue. Unlike strength, endurance develops by increase the oxidative and metabolic capacities due to low-intensity muscle contractions, high repetitions, and a prolonged time period.Endurance can be classified into:

Muscular endurance (local endurance).■Cardiorespiratory endurance (total body endurance), is ■

characterized by having a muscle contract and resist a light load for many repetitions or sustain a muscle contraction for an extended period of time.

3- Power: is the work produced by a muscle per unit of time (force x distance).

Power can be improved by either increasing the work that a muscle must perform in a specified period of time or by reducing the amount of time required to produce a given force.

Factors That Determine Levels of Strength, Endurance & Power

• Size of Muscle– Proportional to cross-sectional diameter of muscle

fibers– Increased cross-sectional area = increased strength

and force production– Hypertrophy

• Increase in muscle size– Atrophy

• Decrease in muscle size

Factors That Determine Levels of Strength, Endurance & Power

• Number of Muscle Fibers

Factors That Determine Levels of Strength, Endurance & Power

• Neuromuscular Efficiency– Strength is directly related to efficiency of the

neuromuscular system– Initial increases in strength during first 8-10 weeks

are attributed to neuromuscular efficiency

Factors That Determine Levels of Strength, Endurance & Power

• Age– Men & women increase strength throughout

puberty & adolescence– Peaks at age 20-25– After age 25, max strength declines 1% annually– Decline is related to physical activity– Able to retard decline in performance through

activity

• Overtraining– Imbalance between exercise and recovery

• Training exceeds physiological and psychological capacity of individual

– Can have negative effect on strength training– May result in psychological or physiological

breakdown• Injury, illness, and fatigue can be indicators

Fast-Twitch vs. Slow Twitch• Slow Twitch Fibers

– Type I or slow oxidative (SO)– More resistant to fatigue– Time required to generate force is greater in slow twitch fibers– Primarily associated with long duration, AEROBIC activities

• Fast Twitch Fibers– Type IIa (fast oxidative glycolytic- FOG)

• Moderately resistant to fatigue– Type IIb (fast glycolytic - FG)

• Fatigues rapidly – true fast twitch– Type IIx – fatigue resistant with force capacity (a<x<b)– Produce quick, forceful contractions – Short-term, high intensity activities, ANAEROBIC activities

•Ratio in Muscle▫Both fiber types exist in individual muscles▫Ratio varies by muscle and by individual▫Postural muscles = % primarily type I fibers▫Power, explosive strength muscles = % type II

fibers

Physiology of Strength Development

• Muscle Hypertrophy – 3 theories– Hyperplasia – in number of muscle fibers

• Genetically determined & does not seem to increase with training

• Evidence exists of fibers splitting – conducted in animals

– Hypothesized increased number of capillaries – partially correct

• No new capillaries• Increase in dormant capillary activity to meet needs

of muscle

Physiology of Strength Development– Reversibility – adaptations of muscle due to training

can begin to reverse within 48 hours of removing training

Other Physiological Adaptations to Resistance Exercise

• Strength of non-contractile structures– Tendons and ligament increase– Increased bone-mineral content

• Improved oxygen uptake– If resistance training is high enough to elicit a

cardiovascular response/adaptation

• Increased metabolic enzymes

Overload Principle– To improve strength, muscle must be worked at a level

higher than it is accustomed to– Muscle will maintain strength if it is trained against a

consistent resistance that it is accustomed to• Existence of current strength & will result in increased muscle

endurance

– Effective training requires a consistently increasing effort against progressively more resistant loads

– In rehabilitation, rate of progression is determined by athlete’s response to specific exercise

• Be mindful of pain when dealing with progression

Aims of Resisted exercise

1- Improvement and maintenance of muscle strength, power and endurance.

2- Increase strength of connective tissues, ligament and tendons.

3- Increase bone mineral density4- improve coordination and balance.4- Increase muscle mass (hypertrophy) and

decrease body fat.5- Increase blood flow of the working muscle.6- Enhance physical performance during ADL .7- Increase heat production and improve repair

and healing process.8- Decrease stress on joint and reduce risk of

soft tissue injury during physical activities.

Precautions for Resistance exercise

1- Cardiovascular precautions which include▲The Valsalva maneuver: which is an expiratory effort against a closed

glottis, should be avoided during resistance exercise, especially during isometric and heavy resistance exercise.

Sequences:Deep inspiration, closure of the glottis, contraction of abdominal muscles,

increased in the intra-abdominal pressures, decreased in venous return leads to a decreased in in cardiac output, a temporary drop in ABP leads to an increase in the H.R.

When the expiration occurs, there is a pronounced increase in blood pressure due to rapid venous blood flow into the heart that leads to a forceful contraction of the heart.

Prevention:- Patient should not hold his breath- Have the patient exhale during the exercise- Ask the patient to count or talk during exercise

2- Fatigue: is the diminished response of a muscle or muscle groups to repeated stimulus. The therapist should be aware of the pattern of fatigue that occur either during the static or dynamic exercise and gear the exercise program accordingly to avoid its occurrence.3- Recovery from exercise: the body must be given time to restore itself to the existed state before the exhaustive exercise.4- Overwork and Overtraining: in heavy resisted training, exercise program must be progressed cautiously to avoid acute muscle fatigue induced individual to stop exercising. Overtraining: a decline in physical performance in healthy subjects due to high-intensity, inadequate rest intervals between training sessions or too rapid progression of exercise. Overwork: progressive deterioration of strength in already weakened muscles by non-progressive neuromuscular disease.

5-Muscle soreness: - Acute Muscle soreness: - Muscle pain develops during or directly after strenuous exercise due to lack of adequate blood flow & oxygen and accumulation of lactic acid and potassium in the exercised muscle.- it is transient and subside quickly when adequate blood flow & oxygen are restored to the muscle.- Delayed-onset Muscle soreness: Muscle tenderness and temporary stiffness develop 12-24 hours after exercise. This may be due to microtrauma to muscle fibers and/or connective tissues that result in tissues degeneration.

6- Substitute motions: it occur if too much resistance is applied during exercise. An appropriate amount of resistance and correct stabilization should be applied to avoid substitute motions.7- Osteoporosis: A reduction of mineralized bone mass associated with an imbalance between bone resorption and bone formation. Resistance exercise must be applied and progressed vary cautiously to avoid pathological fracture.Contraindications include:1- Inflammation: the use of dynamic resisted exercise can lead to increase swelling and more damage to muscle. In this case it can be replaced by low-intensity isometric exercise.2- Pain: sever joint or muscle pain during exercise or 24 hours after it, should be carefully evaluated.