Chapter 6 Managing Impaired Muscle Performance

Overview Muscle is the only biological tissue capable of actively generating tension Muscle is the only biological tissue capable of actively generating tension This characteristic enables human skeletal muscle to perform the important functions of maintaining upright body posture, moving body parts, and absorbing shock This characteristic enables human skeletal muscle to perform the important functions of maintaining upright body posture, moving body parts, and absorbing shock

Skeletal Muscle Skeletal muscle possesses four biomechanical properties: Skeletal muscle possesses four biomechanical properties: –Extensibility: the ability to be stretched or to increase in length –Elasticity: the ability to return to normal resting length following a stretch –Irritability: the ability to respond to a stimulus –The ability to develop tension. The ability of skeletal muscle to develop tension is referred to as a contraction

Muscles An agonist muscle contracts to produce the desired movement An agonist muscle contracts to produce the desired movement An antagonist muscle opposes the desired movement An antagonist muscle opposes the desired movement –Antagonists resist the agonist movement by relaxing and lengthening in a gradual manner to ensure that the desired motion occurs, and that it does so in a coordinated and controlled fashion Muscle groups that work together to produce a desired movement, are called synergists Muscle groups that work together to produce a desired movement, are called synergists

Muscles Most muscles span only one joint Most muscles span only one joint However, there are many muscles in the body that cross two or more joints: However, there are many muscles in the body that cross two or more joints: –The erector spinae –The biceps brachii –The long head of the triceps brachii –The hamstrings –The rectus femoris

Development of Muscle Tension The magnitude of the tensile force generated by a muscle is dependent on a number of factors: The magnitude of the tensile force generated by a muscle is dependent on a number of factors: Type of contraction Type of contraction The force-velocity relationship The force-velocity relationship The ability to recruit motor units The ability to recruit motor units Electromechanical delay Electromechanical delay Force-length relationship Force-length relationship Angle of insertion Angle of insertion Angle of pennation Angle of pennation Stored elastic capabilities Stored elastic capabilities Gravity Gravity Fatigue Fatigue Muscle temperature Muscle temperature

Improving Muscle Performance Muscle performance can be measured using a number of parameters: Muscle performance can be measured using a number of parameters: –Strength: the ability of a muscle to generate force against a specific resistance, or to produce torque at a joint –Endurance: the ability of a muscle to sustain or perform repetitive muscular contractions for an extended period –Power: the product of muscular force and the velocity of muscle shortening

Improving Muscle Strength To increase strength, the load or resistance must be gradually increased during the muscle contraction To increase strength, the load or resistance must be gradually increased during the muscle contraction Strengthening of a muscle occurs when the muscle is forced to work at a higher level than that to which it is accustomed Strengthening of a muscle occurs when the muscle is forced to work at a higher level than that to which it is accustomed

Improving Muscle Strength If the metabolic capabilities of the muscle are progressively overloaded, adaptive changes occur within the muscle: If the metabolic capabilities of the muscle are progressively overloaded, adaptive changes occur within the muscle: –An increase in the size of the muscle (hypertrophy) –An increase in the efficiency of the neuromuscular system –An enhancement of the muscle’s endurance –An improvement in the power of the muscle

Improving Muscle Strength Four main types of strengthening exercise: Four main types of strengthening exercise: –Isometric –Concentric –Eccentric –“Functional”

Improving Muscle Strength The parameters that must be considered when developing an exercise program include: The parameters that must be considered when developing an exercise program include: –Intensity –Duration –Frequency

Improving Muscle Endurance To increase muscle endurance, exercises are performed against light resistance for many repetitions, so that the amount of energy expanded is equal to the amount of energy supplied To increase muscle endurance, exercises are performed against light resistance for many repetitions, so that the amount of energy expanded is equal to the amount of energy supplied

Improving Muscle Power Muscle power is increased by having a muscle work dynamically against resistance within a specified period Muscle power is increased by having a muscle work dynamically against resistance within a specified period –Example: Plyometrics

Specificity of Training Specificity of training involves the principle of the Specific Adaptation to Imposed Demand (SAID) Specificity of training involves the principle of the Specific Adaptation to Imposed Demand (SAID) Aim: To improve the strength and coordination of functional or sports- specific movements with exercises that approximate the desired activity Aim: To improve the strength and coordination of functional or sports- specific movements with exercises that approximate the desired activity

Increasing Flexibility Flexibility training has long been recognized as an essential component of any conditioning program as a means to prevent injury and improve performance Flexibility training has long been recognized as an essential component of any conditioning program as a means to prevent injury and improve performance Two broad types: Two broad types: –Static –Dynamic

Static and Dynamic Flexibility Static flexibility is defined as the passive ROM available to a joint or series of joints Static flexibility is defined as the passive ROM available to a joint or series of joints Dynamic flexibility refers to the ease of movement within the obtainable ROM Dynamic flexibility refers to the ease of movement within the obtainable ROM

Methods of Stretching Passive Passive Static Static Ballistic Stretching Ballistic Stretching Neuromuscular facilitation Neuromuscular facilitation

Delayed Onset Muscle Soreness This type of soreness, which occurs between hours after exercise, may last for up to 10 days This type of soreness, which occurs between hours after exercise, may last for up to 10 days Prevention of this type of muscle soreness involves careful design of the eccentric program including prepatory techniques, accurate training variables and appropriate aftercare Prevention of this type of muscle soreness involves careful design of the eccentric program including prepatory techniques, accurate training variables and appropriate aftercare

Sarcopenia Sarcopenia (sarco = muscle, penia = lack of), is not a disease but rather refers specifically to the universal, involuntary decline in lean body mass that occurs with age, primarily due to the loss of skeletal muscle Sarcopenia (sarco = muscle, penia = lack of), is not a disease but rather refers specifically to the universal, involuntary decline in lean body mass that occurs with age, primarily due to the loss of skeletal muscle When older people maintain muscular activity, the losses in strength with age are reduced substantially When older people maintain muscular activity, the losses in strength with age are reduced substantially

Neuromuscular facilitation The proprioceptive neuromuscular facilitation (PNF) techniques of hold- relax, stretch-relax, and agonist contract-relax can be used to actively stretch the soft tissues. The proprioceptive neuromuscular facilitation (PNF) techniques of hold- relax, stretch-relax, and agonist contract-relax can be used to actively stretch the soft tissues.

Neuromuscular facilitation Hold-relax – autogenic inhibition Hold-relax – autogenic inhibition –An isometric contraction of the range limiting antagonist is performed against slowly increasing resistance –This is followed by a voluntary relaxation by the patient and then passive movement of the extremity by the clinician

Neuromuscular facilitation Hold-relax-active – reciprocal inhibition Hold-relax-active – reciprocal inhibition –Following application of the hold-relax technique, the patient performs an active contraction into the newly gained range of the agonist pattern

Neuromuscular facilitation Contract relax Contract relax –And isotonic movement in rotation is performed followed by an isometric hold of the range limiting muscles in the antagonist pattern against slowly increasing resistance, voluntary relaxation, and active movement into the new range of the agonist pattern

Aquatic exercise The indications for aquatic therapy include instances when: The indications for aquatic therapy include instances when: –Partial weight bearing ambulation is necessary –To increase range of motion –When standing balance needs to be improved –When endurance/aerobic capacity needs to be improved

Aquatic exercise Contraindications include incontinence, urinary tract infections, unprotected open wounds, heat intolerance, severe epilepsy, uncontrolled diabetes, unstable blood pressure or severe cardiac, and/or pulmonary dysfunction Contraindications include incontinence, urinary tract infections, unprotected open wounds, heat intolerance, severe epilepsy, uncontrolled diabetes, unstable blood pressure or severe cardiac, and/or pulmonary dysfunction

Aquatic exercise Pool temperatures should be: Pool temperatures should be: –92 to 95°F for water exercise –85 to 90°F for active swimming –82.4 to 89.6°F for light activity