Strengthening in upper motor neuron lesions is an important part of rehabilitation of the neurological disorders. Your understanding of strengthening in UMN lesions will be clarified by this presentation, which explains how strengthening in musculoskeletal and neurological illnesses differs.

1. STRENGTHENING IN
UMN LESION
ANISHA D KATOLE
FINAL BPTh

2. CONTENTS :
 INTRODUCTION
 INCREASING MUSCLE STRENGTH
 Type of exercise
 Specificity of strength training
 SUMMARY

3. INTRODUCTION :
 The major goal of physiotherapy in neurological rehabilitation is the
optimization of functional motor performance. Major impairments limiting
motor performance are muscle weakness or paralysis, soft tissue contracture,
lack of endurance and physical fitness.
 Here are some general guidelines for strength training in relation to the
optimization of motor control and skill, training to increase physical fitness and
endurance, and methods of decreasing stiffness and preserving soft tissue
length.

4. INCREASING MUSCLE STRENGTH :
 The physiological factors which affect strength are structural and functional.
 The Structural factors include the cross-sectional area of the muscle (its size), the
density of muscle fibers per unit cross-sectional area and the efficiency of mechanical
leverage across joints.
 The functional factors include the number, type and frequency of motor units recruited
during a contraction, the initial length of muscles and the efficiency of cooperation
between synergic muscles involved in the action. In addition, biomechanical factors
also affect strength.
 In addition, biomechanical factors also affect strength.

5.  Strength is a function of the properties of muscle and depends on intact neurological
function. (Buchner and de Lateur 1991).
 It follows that strength training is necessary after stroke to improve the force generating
capacity and efficiency of weak muscles and to improve functional motor performance.
 Skilled motor performance, however , requires the following:
 each muscle involved in the action has to generate peak force at the length appropriate
to the action
 this force has to be graded and timed so synergic muscle activity is controlled for task
and context
 the force has to be sustained over a sufficient period of time
 peak forces must be generated fast enough to meet environmental and task demands
such as increasing walking speed to cross the road at traffic lights.

6.  Factors associated with the nature of the lesion, the patient's pre-stroke physical
condition and subsequent physical inactivity provide, therefore, several compelling
reasons for emphasizing strength training following a stroke, summarized as follows.
 1. Muscle weakness is a major impairment to effective functional performance
 a stroke usually results in some degree of muscle weakness, including paralysis,
primarily as a direct result of a reduction in descending inputs on spinal motoneurons
and of the number of motor units activated.
 the immobility which ensues results in mechanical and functional changes to the
muscles and connective tissue, and predisposes to further reductions in strength
 elderly individuals may have had varying degrees of muscle weakness and reduced
endurance and cardiovascular responses pre-stroke due to a decline in physical activity.

7.  2. There is mounting evidence that strength training is effective following
Stroke
 muscle strength is increased
 increased strength can be associated with improved functional Performance
 when incorporated into an intensive activity programme, exercise capacity and
endurance are also improved.
 3. There is no evidence that spasticity (hyperreflexia) or hypertonus (resistance
to passive movement) increase, and some evidence that they decrease, after
strength training.

8.  Strength training effects are both neural and structural, and include:
1. stimulation of neuromuscular changes due to reorganized drive from supraspinal
centres. Changes include enhanced muscle excitation, improvements in recruitment of
motoneuron pool, inhibition of antagonist muscles, motor unit activation and
synchronization of the firing pattern of motor units (Hakkinen and Komi 1983, Sale
1987)
2. stimulation of metabolic, mechanical and structural muscle fibre changes that result in
larger and stronger muscles due to an increase in actin and myosin protein filaments
(Sale 1987, Thepaut-Mathieu et al. 1988).

9. TYPE OF EXERCISE:
 There are several methods of strength training in use in rehabilitation:
 Isometric exercise: a muscle contraction is performed with little movement or change
in muscle length
 Isotonic exercise: an exercise in which the resistance remains constant; includes active
gravity-eliminated exercise, free weights , weight-loaded machines and elastic band
exercise
 Isokinetic exercise: exercise that uses an isokinetic dynamometer in which the speed is
kept constant and the variable resistance matches the force applied.

10. Single joint and kinetic chain exercises:
 Isotonic and isokinetic exercises
may be performed by isolating one
segment (sometimes called open-
chain exercise). In these exercises,
the limb moves against resistance
with the distal segment free, as in
the seated knee extension exercise.
 Functionally, however, in many
everyday actions, the foot, shank
and thigh behave as a linked
segmental chain.
 The term lower limb kinetic chain
(or 'closed-chain') exercise
(Palmitier et al. 1991) is used to
describe exercises that recruit all
three links together. Movement at
one joint, of necessity, produces
movement of the other joints

11.  Kinetic chain weightbearing
exercises are typically given to
strengthen lower limb extensor
muscles using body weight and
other forms of resistance include
exercises in which the body mass is
lowered and raised over the feet.
 for example, step-ups, modified
squat to stand, heels raise and
lower, and leg press exercises

12.  These exercises take advantage of the specificity principle in that muscles are
exercised concentrically and eccentrically in a movement pattern that shares
some of the dynamic characteristics of commonly performed motor actions
such as sit-to-stand, bending down to pick up objects in standing, stair
climbing and descent (Palmitier et al. 1991)
 In weightbearing kinetic chain exercises, synergistic muscle activity plays a
large part in the action. Consequently, the individual is not only increasing the
strength of a group of muscles but is being trained to control the muscle forces
produced across the segmental linkage.
 There is some clinical evidence that weightbearing exercises for the lower limb
can improve strength and functional performance in individuals with disability.

13.  For example, a programme of this type of strength training was followed by improved
isometric strength, gait and sit-to-stand (STS) performance in children with cerebral
palsy (Blundell et a1. 2002).
 practicing step-up exercises was associated with improved gait after stroke and in
elderly subjects (Nugent et a1. 1994, Sherrington and Lord 1997).

14.  It is likely that in patients with very weak muscles - any method of strength
training, including exercises performed with the distal segment free, may be of
value. There is some theoretical support for the view that, in this situation, any
exercise that stimulates muscle activation and requires the muscle to work
eccentrically, concentrically or isometrically will transfer into improvements in
functional motor performance.
 Isokinetic exercise, where available, may be particularly useful in patients who
have difficulty sustaining appropriate levels of muscle activation through
range. However, when muscles are stronger, i.e. above a certain threshold that
strength training should consist of exercises that are dynamically similar to the
actions being trained in order to train motor control and maximize carryover
into function.
 Exercises are progressed by increasing the number of repetitions, the range of
movement (e.g. height of step) and the amount of resistance or load.

15. Concentric and eccentric exercise:
 The force-producing capacity (tension regulation) of muscle differs during
lengthening and shortening contractions
 Voluntary eccentric contraction {comparison with concentric contraction}
o Produces greater muscle force
o Lower rate of motor unit discharge
 Lesser levels of muscle activation are needed for greater levels of force
(Westing et a1. 1990).

16.  In an normal population, utilizing both concentric and eccentric muscle
contractions in strength training has been shown to produce better gains in
strength than concentric contractions alone.
• When the muscle is actively stretched in eccentric contraction tension in
series elastic component increases stored elastic energy is used in
subsequent concentric action.
 In patients with neuromotor impairment, it is possible that, at the neural level,
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 (Burke et a1. 1978).

17. Elastic band resistance exercise:
 Elastic bands provide an inexpensive and simple means of exercising which can be
carried out by patients on their own.
 Each exercise should start with the slack of the elastic band taken out. One advantage of
the elastic band over hand weights is its ability to provide variable resistance
throughout the range of movement.
 For individuals following stroke the use of these bands is recommended as a means of
increasing muscle strength, preserving or increasing joint range and muscle
extensibility, and encouraging unsupervised exercise for both upper and lower limbs.
 Progression involves increasing intensity of exercise (number of repetitions), load
(using band colour to increase resistance) and frequency (number of times per day).

18. SPECIFICITY OF STRENGTH TRAINING:
 The principle of specificity is usually explained with reference to such factors as the
structure and function of particular muscles, biomechanical constraints such as length
of moment arm, and the nature of synergic cooperation.
 Functional actions are made up of complex movements of the multi-segment linkage
which require strength, coordination and balance.
 Strength training may need to focus on exercising muscles through a specific part of the
range (e.g. calf muscles from fully lengthened to mid-range for stance phase of gait). It
is therefore critical that a close examination is made of the patient's ability to generate
and sustain force as active motor tasks are practiced, and that this is followed up by
exercise and training specifically targeting the muscles in which weakness is evident
and apparently affecting function.

19. Efficacy of muscle strength training after stroke:
 Studies have reported the following changes after periods of strength training and
physical conditioning:
 Increases in muscle strength, improved postural stability and reduction in falls in the
elderly (Aniansson et a1. 1980, Aniasson and Gustafsson 1981, Sauvage et a1. 1992,
Fiatarone et a1. 1990, 1994, Judge et a1. 1993, Tinetti et a1. 1994, Campbell et a1.
1997, Gardner et a1. 2000)
 Increases in muscle strength after stroke (Sunderland et a1. 1992, Engardtet a1. 1995,
Sharp and Brouwer 1997, Sherrington and Lord 1997, Brown and Kautz 1998, Duncan
et a1. 1998, Teixeira-Salmela et a1. 1999,2001 Weiss et a1. 2000).

20.  Many of these studies also document a positive relationship between increased
strength and functional performance.
 For example, increased strength of lower limb muscles (hip and knee flexors
and extensors, ankle dorsi- and plantarflexors) is associated with improvements
in aspects of:
 gait performance (Nakamura et a1. 1985, Bohannon and Andrews 1990,
Nugent et a1. 1994, Lindmark and Hamrin 1995, Sharp and Brouwer 1997,
Krebs et a1. 1998, Teixeira-Salmela et a1. 1999,2001, Weiss et a1. 2000)
 Ability to balance (Hamrin et a1. 1982, Weiss et a1. 2000)
 Stair climbing (Bohannon and Walsh 1991).

21. SUMMARY:
 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.
 Strength training utilizes resistance from body weight, free weights, elastic bands,
isokinetic dynamometry, exercise machines, treadmill walking
 Exercise dosage is increased by increasing repetitions, number of sets, load.
 Strength training is task specific or oriented towards characteristics of tasks to be
learned.
 For endurance, high repetition numbers are practiced at low levels of load, and include
stationary cycling, arm cycling and treadmill walking.
 For very weak muscles, the methods used are those which best facilitate force
generation for that individual and may include simple exercises, biofeedback, mental
practice, electrical stimulation.
 Strength training can be carried out under supervision, independently and in group
circuit training classes

22. REFERENCE:
 Stroke Rehabilitation - Guidelines for Exercise and Training to Optimize Motor
Skill by Janet H Carr EdD FACP Honorary Associate Professor, School of
Physiotherapy, Faculty of Health Sciences, The University of Sydney, Australia
Roberta B Shepherd EdD FACPFoundation Professor of Physiotherapy, Honorary
Professor, School of Physiotherapy, Faculty of Health Sciences, The University of
Sydney, Australia

23. THANK YOU