Manual Muscle Testing

Muscle strength defined

• The ability of contractile tissue to produce tension and a resultant force according to the demands placed on that muscle

The causes of muscle weakness

1. After trauma (e.g. Muscle strain, bone fractures)

2. In presence of disease (e.g. cancer, neurological diseases)

3. After surgery (e.g. surgery to repair soft tissue or fractured/broken bones)

4. In presence of pain

5. After disuse, disuse leads to muscular atrophy

Why does a physiotherapist measure muscle strength

1. To assess (and record) muscle weakness.

2. To monitor the success of a physiotherapeutic intervention.

3. To guide the progression of rehabilitation.

MMT (manual muscle testing)

• a non-invasive assessment method used by a variety of manual therapists to evaluate neuromusculoskeletal integrity

• is used to assess muscle strength

• Used when the muscle is compromised

Characteristics of MMT

• An MMT is a manual form of muscle strength testing which does not require any additional equipment.

• This is the standard way of assessing muscle strength in the absence of specialised equipment and the method students use in the clinical setting

• Manual muscle testing is a qualitative measure

Dynanometer

• is a small device that fits in the examiner's hand and is placed at precise locations on a subject's limb to assess the force generated by various muscles or groups of muscles

Isotonic Contractions

• maintain constant tension in the muscle as the muscle changes length

• can be either concentric or eccentric

Concentric Contractions

• a type of muscle contraction in which the muscles shorten while generating force, overcoming resistance

Eccentric Contractions

• results in the elongation (lengthening) of a muscle while the muscle is still generating force; in effect, resistance is greater than force generated.

• can be voluntary or involuntary

Isometric Contractions

• generate force without changing the length of the muscle

Range of muscle work (muscle excursion)

Inner Range

• This is the shortest length a muscle can be at its point of maximum contraction. It's the position where the muscle's fibres are most shortened from the midpoint.

Outer Range

• This is the longest length a muscle can be stretched to. It's the position where the muscle fibres are most lengthened from the midpoint.

Middle Range

• This is the position between midway between the inner and outer ranges

Clinical significances of ranges of muscle work

• crucial in physiotherapy and rehabilitation

• helps in assessing the range of motion of a joint

• identifies muscle imbalances

• to aid in designing exercises to improve strength and flexibility

EXAMPLE:

• exercises can be tailored to target specific ranges of motion depending on rehabilitation goals

MRC Grading Scale

• 0 = No muscle activation on palpation; gravity counterbalanced/eliminated

• 1 = Trace muscle activation, such as a twitch, without achieving full range of motion; gravity counterbalanced/eliminated

• 2 = Muscle activation with gravity eliminated, achieving full range of motion; gravity counterbalanced/eliminated

• 3 = Muscle activation against gravity, full range of motion

• 4 = Muscle activation against some resistance, full range of motion – relevant to the patients age, sex and occupation.

• 5 = Muscle activation against examiner’s full resistance, full range of motion – relevant to the patients age, sex and occupation

Deconstructing the MRC Muscle Grading Scale

• refers to a muscle or group of muscles being tested for its strength

• the muscle being tested is dependant on the physiotherapists assessment if the patient’s clinical presentation

Resistance

• refers to the manual resistance provided by the physiotherapist/ examiner with their hands as to counteract the patient’s movement while testing grades 4 and 5

• can be gradual, moderate or maximum

Range of motion (muscle testing context)

• refers to the active ROM the patient can reach based on their will as a muscle produces tension

Limitations of the MRC grading scale

• There may be individual variation in reporting

• Only assesses muscles contracting in a concentric manner

• The scale may not be applicable in all patient populations

Contraindications to measuring muscle strength

Contraindication = a situation, symptom or condition that makes a particular treatment or procedure unsuitable or inadvisable for a person due to potential for harm

• When the test may disrupt the healing process

• Cause further injury

• Exacerbate or worsen a patient’s condition

• unhealed/ unstable joint

• dislocation or unstable joint

Precautions to measuring muscle length

• history cardiac problems

• where fatigue may worsen a patient’s condition

• certain surgical procedures

• presence of pain