Muscle strengthening

Why is adequate muscle strength important?

• Muscles provide support for joints.

  Rationale: Without adequate muscle support - greater rate of wear & tear in joints

• Optimum Function:

  Rationale: Adequate muscle strength allows the body to keep up with the demands of life.

  These demands depend on age, occupation and gender

Indications for muscle strengthening exercise

1. Extended periods of immobilisation causing muscle atrophy

2. After an injury, a patient needs to regain adequate muscle strength to prevent re-injury

3. In the presence of debilitating disease

4. Effects of postural dysfunction

Muscle strength definition

• Ability of contractile tissue to produce tension and a resultant force based on the demands placed on that muscle

Factors that affect muscle strength

1. Physiological strength: depends on factors such as muscle size, the cross-sectional area of the muscle and its responses to training.

2. Neurological strength of impulse: how weak or how strong the signal is that tells the muscle to contract

3. Mechanical strength: refers to a muscle’s pulling force and the way those forces can be changed using bones and joints as lever

Cardiovascular endurance

• The capacity to maintain strenuous activity of multiple muscle groups for prolonged periods of time.

• Is the aerobic activity of the cardiovascular system to supply oxygen to the muscles during prolonged physical activity.

EXAMPLES :

• running, cycling and swimming

Isokinetic contraction

• When muscle contracts and shortens at a constant rate of speed, despite possible changes in external resistance

EXAMPLE:

• leg work done while riding a stationery bike

Manual Muscle Tes

• Application of increasing resistance to produce a concentric contraction of the muscle tested until a maximum contraction is reached

Isometric Test (manual testing)

• allows for structural differentiation because joint motion is prevented, and the test is isolated to the muscle’s isometric contraction

One-repetition maximum (1RM)

• the maximal load with which a task (movement) can be performed defined as “the greatest load (in kg) that can be fully moved (lifted, pushed or pulled) once, without failure or injury

One-repetition maximum (1RM) calculation

• 1RM = (0.033 x RTF x load in Kg) + load in Kg

Components of Muscle Performance

There are 3 components to improve muscle performance:

1. Muscle Strength

2. Muscle Power

3. Muscle Endurance

Muscle power

• The maximum force that a muscle or muscle group can generate in a minimum time. Its development depends on the right balance between speed and strength on a specific skill that requires explosiveness

To increase power you can:

1. Increase force (e.g., lift heavier weights),

2. Increase distance (e.g., move the weight through a greater range of motion),

3. Decrease time (e.g., perform the movement faster

Power training convention

• High-intensity, low-rep exercises.

• Fast execution of movements

• Adequate rest between sets to maintain explosivenes

Strength training convention

• high load/resistance and a low number of reps

• not dependant on time

Endurance

• The ability to perform low-intensity, repetitive or sustained activities over a prolonged period of time

Muscle endurance

• The ability of a muscle to sustain an isometric contraction or continued (concentric, eccentric) isotonic contractions

Principles of strengthening weak muscle

1. Overload

2. SAID

3. Reversibility

Overload

• An increased load or resistance should be applied to muscles to improve muscle performance

Sub principles of overload

1. To maintain muscle strength do not change load.

2. To increase muscle strength progressively increase: load & volume (reps, sets, frequency)

SAID (Specific Adaptation to Imposed Demand)

• the human body or in this case skeletal muscles will adapt

  specifically in response to the demands and stresses placed on it

Reversibility

• activity must continue at the same level to keep the

  same level of adaptation in muscle tissue. As activity declines, called detraining, muscle adaptations will regress

Types of exercise

1. Open kinetic chain exercise

2. Closed kinetic chain exercise

3. Resisted exercsie

Open kinetic chain exercise

• Movement when the distal segment moves freely in a non-weight bearing position

• Limb movement occurs distal to moving joint due to contraction of muscles that cross the joint

Open chain

• better for isolating movement to specific muscle group and improving control of a specific movement

Closed kinetic chain exerci

• The movement of the proximal body segment on a fixed distal segment. The extremity exercised remains in constant contact with the immobile surface, usually the ground

• promotes co-activation of muscle groups and dynamic

  stabilisation as well as improved proprioception, balance and neuromuscular con

Characteristics of closed kinetic chain exercise

1. Distal segment remains fixed in place

2. In weight-bearing position

3. Interdependent joint movement; predictable movement in adjacent joints

4. Movement of segment may occur distal/proximal to moving joint

5. Muscle activation in multiple muscle groups distal and proximal to moving joint

6. Internal stabilisation by means of muscle actio

Resisted exercise

• exercise whereby muscles contract against an external force

Benefits of resisted exercis

1. Improves mobility

2. Increased strength of connective tissues e.g. tendons

3. Increased bone mineral density (indicator of bone strength)

4. Decreased joint stress

5. Reduced risk of soft tissue injury

6. Improved capacity to repair (heal) damaged soft tissue

7. Possible improvements in balance in some population

Aesthetic and psychological benefits of resisted exercise

1. Positive changes in body composition: increased lean muscle mass and decreased body fat

2. Enhanced feelings of well-being

3. Improved perception of disability