Therapeutic Techniques to Increase Muscle

Strength

PT 154: Therapeutic Exercises IIIMs. Mary Grace M. Jordan, PTRP

December 1, 2009

As physical therapists…

“…one of the major goal of physiotherapy in neurological rehabilitation is the optimization of functional motor performance..”

Major impairments limiting motor performance Muscle weakness or paralysis Soft tissue contracture Lack of endurance Physical fitness

Muscle Strength The ability of contractile tissue to produce tension

and a resultant force based on the demands placed upon the muscle.

Functional Strength…“The ability of the neuromuscular system to produce,

reduce, or control forces, contemplated or imposed, during functional activities, in a smooth, coordinated manner.”

Learning objectives… Discuss muscular weakness, disuse

weakness, and paralysis Review the principles of strength training Discuss the following:

Strength training regimes Isotonic vs. Isometric vs. Isokinetic exercises Open chain vs. Close chain exercises Complications of strength training Considerations in force gradation

Learning objectives… Discuss concepts of resistance training, PNF,

and Task-oriented approach to increase strength of neurologic and developmental conditions

Discuss evidence of technique effectiveness

Physiologic factors which affect strengthSTRUCTURAL Cross-sectional area Density of muscle

fibers per unit cross-sectional area

Efficiency of mechanical leverage across joints

FUNCTIONAL Number, type, and

frequency of motor units recruited during a contraction

Initial length Efficient cooperation

between synergic muscles

Strength is therefore…

A function of the properties of muscle and depends on intact neurological function.

(Buchner and De Lateur, 1991)

Skilled motor performance requires that… Each muscle involved in the action has to

generate peak force at the length appropriate to the action

Force has to be graded and timed so synergic muscle activity is controlled for task and context

Skilled motor performance requires that… Force has to be sustained over a sufficient

period of time

Peak forces must be generated fast enough to meet environmental and task demands

Can strength impairments be reliably measured in a patient

with a CNS lesion?

Assumptions… Measuring strength was not appropriate Primary impairment affecting functional

performance was not weakness but spasticity Strength training in the CNS patient was

considered contraindicated, since it was believed that strength training would increase tone problems (Bobath, 1978; Davies, 1985)

Recent research says… Paresis is an important factor in impaired

functional performance as spasticity. Strength can be measured in 3 ways:

Isometrically Isotonically Isokinetically***Alternative: dynamometers

Muscle weakness and paralysis… Results in loss of movement or stability of a

particular joint Creates a state of muscular imbalance which

affects all the groups concerned in the production of coordinated movements

“CONTRACTION is the only means by which muscle power can be maintained or increased…”

Muscle weakness and paralysis…

“…any lesion or habit which prevents or limits contraction will result in muscle wasting”

Paralysis complete loss of ability to contract

Paresis partial loss or a muscle may be merely weak or sub-

normal

Muscle weakness and paralysis… Causes1. Lesions affecting the

Anterior Horn Cells2. Lesions affecting the

Motor Pathways3. Lesions affecting the

Muscle Tissue4. Reduced endurance

due to decline in physical activity.

Disuse Weakness… A minimum level of strength

is necessary for the performance of everyday motor task.

Strength requirements of people fluctuate over their lifetimes, and even from day to day.

The neuromuscular system is capable of accommodating to these fluctuations.

Disuse Weakness…A patient may not use his

muscles because… He cannot He does not need to He will not

How will you know if its TRUE weakness or APPARENT

weakness?

Hence…

Strength training

…is necessary after stroke to improve the force generating capacity and efficiency of weak muscles and to improve functional motor performance.

Treatment of impaired strength Focus on generating force to move a body

segment or alternatively, generating force to resist a movement.

Use of PRE Use of Isokinetic equipments Eccentric vs. Concentric strength training Task-specific circuit training

Principles of Strength Training Overload (resisted

work) Progression Specificity Reversibility

Strength training regimes Static, Dynamic, and Isokinetic Progressive resistance exercises Use of manual resistance Use of light weights Use of isokinetic training systems

Strengthening regimes

What to use?

Isotonic vs. Isometric vs. Isokinetic

Open chain vs. Close chain exercises

Therapeutic techniques to increase muscle strength Resistance exercises Proprioceptive Neuromuscular Facilitation Motor Re-learning Program / Task-oriented

approach

Kinetic chain exercises… Are given to strengthen lower limb extensor

muscles using body weight (i.e. step-ups, modified squat to stand, heel raise, leg press)

Take advantage of the specificity principle as muscles are exercised concentrically and eccentrically in a movement pattern that shares the dynamic characteristics of commonly performed motor actions (i.e. sit-to-stand, bending down to pick objects, stair negotiation).

Eccentric vs. Concentric exercise… Voluntary eccentric contractions produce

greater muscle force than concentric muscle contraction.

Eccentric exercise has greater mechanical efficiency and has lesser metabolic energy cost than concentric exercise.

Studies showed that… Utilizing both concentric and eccentric

muscle contractions in strength training has been shown to produce better gains in strength than concentric contractions alone.

(Hakkinen and Komi, 1981)

Quick stretch… Concentric activation of weak muscles may

be facilitated by the enhanced muscle spindle activity occurring as a result of the rapid switching from eccentric to concentric muscle activity.

If an eccentric contraction immediately precedes a concentric contraction, concentric phase generates more force due to the effect of the stretch-shortening cycle.

Elastic band resistance exercise… An inexpensive and simple means of exercising

which can be carried out by patients on their own. Provides variable resistance throughout the range of

movement There is some difficulty controlling the exact amount

of resistance Recommended as a means of increasing ms.

Strength, preserving or inc. jt. range and ms. extensibility, and encouraging unsupervised exercise.

PNF An approach to therapeutic exercise that

combines functionally based diagonal patterns of movement with techniques of neuromuscular facilitation to evoke motor response and improve neuromuscular control and function.

PNF techniques Repeated contractions Dynamic reversals of antagonists Stabilizing reversals Rhythmic stabilization Combination of isotonics Repeated stretch from beginning

of range Repeated stretch throughout the

range

Motor Re-learning Program Task-oriented approach to

improve motor control focusing on re-learning of daily activities.

4 steps Analysis of task Practice of missing components Practice of task Transference of learning

What time / phase should you start implementing

strengthening exercises?

What do you need to consider in grading the force that you will apply to your patient?

Resistance exercises Any form of active exercise in which a

dynamic or static muscle contraction is resisted by an outside force, applied either manually or mechanically.

Take note: Warm-up Placement of resistance Direction of resistance Stabilization Intensity/Amount of resistance Number of repetitions and sets; rest

intervals Monitor patient’s response Cool-down

Eliciting activity in very weak muscles Grade 2-3 Partial body weight resistance Resistance through a small range of

movement Lifting small weights through a limited range Elastic band exercises Concentric and eccentric exercise on an

isokinetic dynamometer

Eliciting activity in very weak muscles Grade 0-1 More studies are needed to explore training

of severely weakened or paralyzed muscles In theory, since lower levels of muscle

activation are required for the same force effect in eccentric compared to concentric exercise, attempts at eccentric contraction may enable an individual with very weak muscles to improve activation.

Resistance exercises Precautions

Valsalva maneuver High-risk patients

Coronary artery disease Myocardial infarction Cerebrovascular disorders Hypertension

S ubstitute motions Overwork weakness

Complications to strength training Spasticity Incomplete innervation Muscle substitution Effect of drugs on exercise Effects of length changes on

muscle

How to prescribe strengthening

exercises?

Basic considerations… Dosage can be increased by increasing the

number of repetitions, the number of sets, and the resistance provided.

Muscles should be exercised to the point of fatigue but not pain in order to obtain some change.

Patients should be warned that they may experience a small degree of delayed muscle soreness.

Basic considerations… Strength training utilizes resistance from body

weight, free weights, elastic bands, isokinetic dynamometry, exercise machines, treadmill walking.

Strength training can be carried out under supervision, independently and in group circuit training classes.

Basic considerations… The exercise should be specific as possible to

the functional actions being trained to ensure carryover.

In the case of patients with very weak muscles, any type of exercise which results in generation of some force can be practiced.

Strength training is carried out with sub-maximal loads (as a general rule 10 repetitions at 50-80% of maximal possible 1RM load with a goal of 3 sets)

Is there evidence on the effectiveness of the

techniques?

Studies… Research now is documenting the

contribution of impaired strength to functional limitations in patients with CNS lesions.

Led to a growing awareness of the need to examine and document weakness in the patient with CNS pathology.

Training programs appear to be effective in improving strength; the degree to which they affect other primary impairments is not clear.

Studies reported…

The following changes after periods of strength training and physical conditioning:

Increases in muscle strength, improved postural stability, and reduction of falls in the elderly. (Aniansson et al 1980, Aniasson and Gustafsson 1981, Sauvage et al 1992, Fiatarone et al 1990,1994, Judge et al. 1993, Tinetti et al. 1994, Campbell et al. 1997, Gardner et al. 2000)

Increases in muscle strength after stroke (Sunderland et al. 1992, Engardt et al. 1995, Sharp and Brouwer 1997, Sherrington and Lord 1997, Brown and Kautz 1998, Duncan et al. 1998, Teixeira-Salmela et al. 1999, 2000, Weiss et al. 2000)

Studies reported… Improvement in gait performance (Nakamura et al,

1985, Bohannon and Andrews 1990, Nugent et al 1994, Lindmark and Hamrin 1995, Sharp and Brouwer 1997, Krebs et al. 1998, Teixeira-Salmela et al. 1999, 2000, Weiss et al. 2000)

Improvements in the ability to balance (Hamrin et al. 1982, Weiss et al. 2000)

Improvements in stair climbing (Bohannon and Walsh 1991)

Strengthening exercises for the pediatric population…

Strengthening exercises for the pediatric population…

In order to increase a child’s strength… Progress the movement from a gravity-eliminated

movement to one that is working against gravity. Alter the amount of assistance given so that the

child has to use greater force control. Increasing the number of repetitions or

lengthening the time of exercise will help improve endurance.

Coordination should improve with an increase in strength and endurance, depending on the lesion.

In order to increase a child’s strength… Progressive resistive exercises, isometric and

isokinetic training programs can be used for children who demonstrate adequate cooperation.

For the younger child, age appropriate play, adaptive toys, and games can serve the same purpose.

Practice of bimanual activities Engagement into sports is recommended.

Learning objectives… Discuss muscular weakness, disuse

weakness, and paralysis Review the principles of strength training Discuss the following:

Strength training regimes Isotonic vs. Isometric vs. Isokinetic exercises Open chain vs. Close chain exercises Complications of strength training Considerations in force gradation

Learning objectives… Discuss concepts of resistance training, PNF,

and Task-oriented approach to increase strength of neurologic and developmental conditions

Discuss evidence of technique effectiveness

Laboratory sessionAssignment: Identify muscle groups that are involve and formulate

exercises (using resistance, PNF, and MRP techniques) for the following activities:

1. Rolling from supine to right side-lying2. Long sitting from supine3. Standing from short sitting4. Walking:Initial contact, Midstance, and Swing phase5. Ascending stairs6. Descending stairs7. Bathing8. Dressing upper garments9. Dressing lower garments10. Carrying shopping bag weighing 2 kilos using the right hand11. Use of bilateral arm crutches or walker

Microsoft Office Word 97 - 2003 Document

References: Basmajian, J. & Wolf, S. (1990). Therapeutic exercise (5th

ed.).Baltimore:Williams & Wilkins. Crosbie, J & McConnell, J. (1993). Physiotherapy: Foundations

for practice: Key issues in musculoskeletal physiotherapy. Oxford:Butterworth-Heinemann Ltd.

Gardiner,M.(1981).The principles of exercise therapy (4th ed).London: Bell & Hyman Ltd.

Kisner,C. & Colby, L. (2002). Therapeutic exercise:Foundations and techniques (4th ed.). Philadelphia:F.A. Davis Company.

Shumway-Cook, A. & Woollacott, M. (2001). Motor control: Theory and practical applications (2nd ed.). Philadelphia:Lippincott Williams & Wilkins.

Thank you and see you in the laboratory sessions…