Unit 3

• Muscle performance testing offers insights into a patient’s strength, endurance, power, and functional capabilities.
• These tests help diagnose conditions, tailor rehabilitation programs, monitor progress, and guide return-to-activity decisions.
• Muscle performance testing enhances clinical decision-making, informs exercise prescription, and contributes to improved patient outcomes.
• Mastering muscle performance testing techniques enables physical therapists to effectively evaluate and improve muscle function.
• Limited muscle performance can be linked to body structure functional impairments, activity limitations, and participation restrictions.
• A direct deficit in muscle performance may cause a functional deficit, like the inability to lift a child.
• Indirect deficits can contribute to poor movement patterns and postures and/or excessive tissue load and stress, possibly leading to injury.
• Work, defined as Force x Distance, signifies a muscle's capacity to do work.
• Muscle performance is influenced by neurological, biochemical, biomechanical, metabolic, cardiovascular, respiratory, cognitive, and emotional factors.
• The key elements of muscle performance include strength, endurance, and power.
• Impaired muscle performance is related to weakness or atrophy, and factors like disease, injury, disuse, immobilization, and inactivity can contribute.

Definitions of Muscle Performance

• Strength is the ability to produce tension and resultant force based on muscle demands.
• Power involves the rate of performing work; the product of force and velocity as well as the number of repetitions of a given intensity in a given amount of time.
• Endurance is the ability of muscle groups performing a movement to sustain that movement; it includes cardiopulmonary and muscle endurance.

Muscle Performance: Strength

• Factors influencing strength include cross-sectional size of muscle, length/tension relationship, recruitment of motor units, and type of muscle contraction.
• Fiber type distribution in the muscle, energy stores and blood supply, speed of contraction and the patient motivation are all factors affecting muscle strength.

Muscle Performance: Endurance

• Endurance is a general term referring to the ability to perform low-intensity, repetitive/sustained activities over a long period.
• Cardiopulmonary endurance, or total body endurance, relates to repetitive, dynamic motor activities, such as walking, biking, or swimming that use large muscle groups.
• Muscle endurance is fatigue resistance in the muscle.

Assessing Muscular Strength

• Common methods include gross strength testing, Manual Muscle Testing (MMT), 1 repetition maximum, dynamometry isokinetic testing, and isometric strength testing for muscle integrity.
• MMT involves assessing muscle groups and specific muscles.
• One repetition maximum is the maximum resistance that can be lifted one time.

Assessing Muscular Endurance

• Measurements include counting the maximum number of repetitions of muscular contraction, reps/distance before fatigue, monitoring functional activity over a time period and evaluating cardiovascular endurance with tests like the 6-minute walk test.

Manual Muscle Testing (MMT)

• MMT estimates relative muscle strength and manually assesses a muscle’s strength and contractility.
• Evaluating muscle strength with MMT shows neurologic deficits and can differentiate true weakness from imbalance or poor endurance.
• MMT can also be called motor testing, muscle strength grading, or manual muscle testing.
• Accurate strength assessment relies on morphological and neural factors, including muscle characteristics, muscular and neurologic performance.

Terminology and Concepts in MMT

• Make testing involves the examiner exerting just enough force to prevent joint movement which makes an isometric test.
• Break tests use enough force to overcome the patient's resistance, causing joint movement.
• Patient position/test position should be specific to support accuracy and reliability for the patient and test part position with gravity minimized or resisted.
• Pressure/Resistance involves the amount of force that opposes test movements.
• Substitution involves compensation for lack of strength in the tested area.
• Isometric Contraction is muscle contraction, but the muscle only shortens slightly in length and the joint does not move.
• Concentric Contraction involves the muscle shortening with contraction and the joint moves anti-gravity.
• Eccentric Contraction involves the muscle lengthening with contraction and the joint moves anti-gravity.
• Agonist is a contracting muscle whose action is opposed by another muscle ex(biceps brachii), the other relaxes (triceps brachii).
• Fixation means the stability of a body part.
• Synergists may work as fixators, secondary movers, or neutralizers.

Purpose of MMT/Strength Testing

• MMT aids in detecting of weakness, which may be due to nerve involvement, disuse atrophy, stretch weakness, pain, fatigue, or general patient status
• MMT aids in detecting muscle imbalances by synergists and antagonists
• MMT aids in determining the muscles' ability to function in movement and to provide stability and support
• MMT can help determine a patient's motor control and movement patterns which includes substitutions and compensations
• MMT serves to isolate and identify the structure that is causing pain or injury and examines central and peripheral nervous system function.

MMT and Dynamometry

• A dynamometer evaluates muscle performance and is used for resistive exercises.
• Combining a hand-held dynamometer with MMT improves grading accuracy; the results are specifical and quantifiable.

Joint vs. Muscle Relationships to MMT

• For 1 joint muscles, the optimal test position is Midrange.
• 1 joint muscles shorten through full ROM.
• For 2 joint muscles, optimal test position is End range.
• 2 joint muscles cannot fully contract through full ROM.
• When a two or multi-joint muscle can no longer effectively generate force due to being in a shortened position the result is Active Insufficiency.

Isolating Muscles During MMT

• With 2 joint muscles, put the two joints in a shortened position at one of its joints so it cannot produce optimal force.
• One tests one joint muscles from another because the muscles may have similar actions and one varies position for accurate assessment isolating each specific action

Process and Sequence for MMT

• Sequencing of the MMT includes using the right position, determining ROM, and stabilizing
• The sequence also includes location lever am and direction of pressure to be applied.
• To properly sequence PTs should think ahead and explain what to do for a test.

Anti-Gravity (AG) vs. Gravity Eliminated (GE)

• Antigravity (AG, gravity-resisted) relates to movement against gravity and is functional while gravity eliminated (GE, gravity minimized) relates to movement in the horizontal plane in a position that eliminates gravity and is used when the resistance is too great.

Range of Motion

• To determine PROM the limb is taken through classical PROM to determine if there are restrictions and prepare what is going to be tested
• To determine the ability of movement the patients AROM is is observed

Stabilization

• Stabilization is best facilitated by a firm surface, body weight or other muscles in order to best isolate muscles and allow for the greatest effort.

Lever Arm and Pressure

• Apply pressure near the DISTAL end of the bone that the muscle to be tested inserts (the longest lever arm) this applied opposite to the line of pull of the muscle

Sequencing of MMT

• Think ahead, explain what to do, considering positions and test all needed muscles before moving the position
• Testing order example: prone-Glut max & Hamstrings, sidelying Hip abductors & adductors, seated -Hip flexors, Quads, Hip Internal & External rotators

Muscle Length Testing

• Muscle length is the ability of a muscle crossing a joint to lengthen within its available ROM.
• The terms muscle length and flexibility are considered synonyms that often determines normal arthrokinematics/biomechanics
• Normal muscle length relates to joint alignment, biomechanics, osteokinematic motions.
• Multi action muscles test are the range of multiple cardinal plane motions.
• With passive insufficiency, the hamstring muscle group is lengthened but full hip flexion and knee extension can not occur at the same time.

Factors that Can Affect Muscle Length and Extensibility

• Prolonged Immobilization, Paralysis, weakness, connective tissue can cause adaptive shortening.
• Direct injury to a muscle, immobilization, Adhesions and fibrous tissue deposition can decrease extensibility.
• One-joint and Multi Join muscles have different results in terms of muscle flexibility and muscle extensibility
• Researches that flexibility changes with age and is gender differences
• Mobility could be specific and changes can occur, flexibility accommodate the requirements to adapt with demands. Factors in joint testing include comfortable the sensation of pain

General Concepts for Muscle Length Testing (MLT)

• Key points include Passively separate the insertion or distal attachment and Lengthen opposite of muscle action across all the planes.
• Tips for MLT include stabilizing the proximal attachment to prevent compensation and communicating effectively.
• Assess what is the normal feel and Interpret based on if limited, excessive, or at normal length

Technique Performance Criteria

• Technique performance should include the purpose, body placement and how to interpret a limb during test
• The body needs to have time to rest in the position. Evaluate the response of the limb during test.

Range of Motion Determinations

• If not a standardized value, muscle length should allow full or near-full joint ROM.
• Limb symmetry can be considered which is acceptable but normal length is note always there. Symptoms: if a patient experiences pain during the MLT, muscle tissue was likely injured or guarded.

MLT Interpretation

• A limited length can cause functional deficit, a biomechanical change that has affect on the muscle function or mobility.
• Altered biomechanics can negatively affect movement efficiency while decreased range of motion or injury.