resistance exercise

Resistance exercise

an activity in which dynamic or static muscle contraction is resisted by an outside force applied manually or mechanically.

• Also referred as “resistance training”

Muscle performance

is the capacity of a muscle to do work (force × distance)

Strength (muscle strength)

Broad term that refers to contractile elements of muscle producing force.

Strength training

using muscle force to raise, lower, or control heavy external loads

Muscle power

• related to the strength and speed of movement

• rate of performing work.

Power training

plyometric training

Endurance (muscle endurance)

ability of a muscle to contract repeatedly against an external load, and resist fatigue over an extended period of time

Endurance training

light external load, many repetitions over an extended period of time

Overload principle

To improve muscle performance, the muscle must be challenged to perform at a level greater than that to which it is accustomed.

Overload principle focus

This principle focuses on progressively loading muscle by manipulating:

• intensity (how much external resistance) of exercise

and

• volume (repetitions, sets, or frequency) of exercise

strength training

external resistance is incrementally and progressively increased

endurance training

emphasis is on increasing time and number of repetitions

Specific adaptation to imposed demands (SAID) principle

• This principle will guide therapists to choose exercise parameters to best meet functional needs and goals.

Specificity of training

• For example, if functional activity requires more muscular endurance than strength, lower intensity exercises performed over a longer time should be emphasized

Detraining (reduction in muscle performance)

• begins 1 week or 2 after the cessation of resistance exercises

• training effects are lost in an average of 2 to 4 weeks.

Fatigue

• Complex phenomenon affecting muscle performance

• Types of fatigue

  • Muscle (local) fatigue

  • Cardiopulmonary (general) fatigue

Muscle (local) fatigue

• Gradual decline in force-producing capacity of neuromuscular system

  • Leads to decrease in muscle strength

• Normal and reversible response

• Fiber-type distribution in a muscle (Type I and Type II), affects resistance to fatigue

Muscle fiber Type I

• Slow-twitch, tonic

• Found in postural muscles

• Low level tension, extended period of time

Muscle fiber Type IIX

• Fast-twitch, phasic

• High amount of tension, short period of time

• Susceptible to fatigue

muscle fiber types and resistance to fatigue

Cardiopulmonary (general) fatigue

• Systemic diminished response to prolonged physical activity (e.g or repetitive work)

• Related to the body’s ability to use oxygen efficiently

Factors that influence fatigue

• Health status

• Diet

• Lifestyle (sedentary or active)

Signs and symptoms of fatigue

• Muscle pain and cramping

• Shaking or trembling of the muscle

• Unintentional slowing of contraction velocity

• Movements are jerky or inconsistent

• Inability to complete the movement pattern

through range of available motion

• Use of substitute motions

• Inability to continue low-intensity physical

activity

Skeletal muscle adaptations - Hypertrophy

increase of individual muscle fiber size

Skeletal muscle adaptations - Hyperplasia

increased number of muscle fibers

Dosage of exercise includes:

• Intensity

• Volume

• Frequency

• Duration

Intensity

• Amount of external resistance (exercise load or training load)

• Submaximal vs maximal exercise loads

Intensity - Repetition maximum (RM)

• Greatest amount of weight that can be moved through full ROM a specific number of times before fatiguing

  • Examples:

    • 10-RM - amount of weight that could be lifted and lowered 10 times through the ROM

    • 1-RM - just one time

Volume

Total repetitions x intensity (lbs)

• Example:

  • 3 sets x 10 reps with a 5-lb dumbbell= 30 (total repetitions) x 5 lbs= 150 lbs of volume

Volume - Strength

• 60% to 80% of a 1-RM

• 8 to 12 repetitions for 2 or 3 sets

Volume - endurance

• low resistance

• 3 to 5 sets of 40 to 50 repetitions

Frequency

Number of exercise sessions per day or per week

• beginner 2-3

• intermediate 3-4

• advanced 4-7

Duration

• Total number of weeks or months

• Lifetime duration for maintenance

Rest interval

• Higher exercise intensity a longer rest interval is needed

• Moderate-intensity resistance training, a 2 to 3 minute rest period after each set

Determinants of resistance exercise

• Alignment

  • Stabilization

  • Intensity

  • Volume

  • Exercise order

  • Frequency

• Rest interval

  • Duration

  • Mode

  • Velocity

  • Periodization

  • Integration of exercises into

  functional activities

Manual resistance exercise

• Type of active-resistive exercise, external resistance provided by a therapist.

• Also can be self-generated manual resistance.

Mechanical resistance exercise

Form of active-resistive exercise; external resistance applied through equipment or mechanical apparatus.

Isometric Exercise (Static Exercise)

Muscle contracts without an appreciable change in length and without joint motion

Isometric Exercise (Static Exercise) - Types: Muscle setting exercises

• Low-intensity isometric contractions against little to no resistance

• For acute stage of healing

Isometric Exercise (Static Exercise) - Types: Stabilization exercises

To improve postural stability or dynamic joint stability.

Isometric Exercise (Static Exercise) - Types: Multiple-angle isometrics

• Resistance at multiple joint positions

• Goal of exercise is to improve strength throughout the ROM

Isometric Exercise (Static Exercise) - Duration of muscle activation

• Held for 6 seconds and no more than 10 seconds

• 10-second contraction allows a 2- second rise time, a 6-second hold time, and a 2-second fall time

Isometric Exercise (Static Exercise) - Joint angle

• Muscle strength gains occur only at or closely adjacent to the joint angle at which resistance is applied

• Physiological overflow 10° in either

direction

Dynamic Exercise - Concentric

Dynamic muscle activation and physical shortening of the muscle (e.g lifting a weight)

Dynamic Exercise - Eccentric exercise

Dynamic muscle activation; physical lengthening of the muscle occurs (e.g lowering a weight)

Dynamic Exercise - Concentric vs Eccentric

• Greater loads can be controlled with eccentric exercise

• Greater loads can be lowered than can

be lifted

• Eccentric muscle contractions generate less fatigue than concentric contractions

• Gains in muscle strength and mass are greater with eccentric than with concentric training

Isokinetic exercise

• Isokinetic: movement at a constant velocity

• The joint angular velocity is predetermined and held constant by isokinetic dynamometer

• Training velocities tend to be substantially slower for eccentric training, ranging from 30° to 120°/sec with most eccentric training initiated between 60° and 120°/sec.

Closed kinetic chain exercise

• Distal segment remains fixed or in contact with support surface

• Typically performed in weight-bearing positions

• Internal stabilization by means of muscle action, joint compression and congruency, and postural control

• Example: Squatting down

Open kinetic chain exercise

• Distal segment moves in space

• Typically performed in non-weight-bearing positions

• External stabilization (manually or with equipment) often required

• Example: Swinging the leg

Progressive resistance exercise

• System of dynamic resistance training in which a constant external load is applied to the contracting muscle by some mechanical means and then incrementally increased.

• PRE concept introduced by DeLorme

Blood Flow Restriction (BFR)

• Strength training regimen that decreases blood flow to a muscle an constricting device

• Pressure intended to maintain sufficient arterial blood flow while occluding venous flow distal to the device

• Muscle hypertrophy is enhanced.

• At least 20% of 1-RM over a period of at least 6 weeks

Precautions for resistance exercise 1

• 1

• Ambient temperature comfortable

• Select clothing for exercise

• Pain should not occur during exercise

• Do not initiate resistance training at a maximal level to minimize delayed-onset muscle soreness (DOMS)

• No resistance across an unstable joint or distal to a fracture site that is not completely healed

• Have the patient avoid breath-holding to prevent the valsalva maneuver; emphasize exhalation during exertion.

Precautions for resistance exercise 2

• 2

• Avoid uncontrolled, ballistic movements

• Prevent incorrect or substitute motions

• Avoid exercises that place excessive, unintended secondary stress on the back.

• Be aware of medications a patient is using

• Adequate rest intervals between exercise sessions

• Discontinue exercises if the patient experiences pain, dizziness, or unusual or precipitous shortness of breath.

Delayed-onset muscle soreness S/S

Muscle soreness and aching beginning 12 to 24 hours after exercise, peaking at 48

to 72 hours, and subsiding 2 to 3 days later

Contraindications for resistance exercise

• Pain

• Inflammation

• Severe cardiopulmonary disease