Lecture 2: Strength Training pt.1

What is strength?

the greatest measurable force a muscle exerts to overcome a resistance in a single, maximal effort

In PT, what does strength mean?

muscles should be able to generate enough force to meet physical and functional demands of the patient

What is functional strength?

the ability of the neuromuscular system to produce and control forces in a coordinated manner during activities

How do you increase strength?

by lifting, lowering or controlling heavy loads using a low number of reps or over a short time period

What are the two main factors that contribute to an increase in strength?

a result of neural adaptation and an increase in the size of the muscle fiber

What is power?

measurement of how fast a muscle can contract to produce force through the ROM

What is the formula to find power?

power = force x velocity

What is necessary (1st step) for a muscle to develop power?

adequate muscle strength is necessary for a muscle to develop power

What are some ways to increase power?

• changing the rate

• reducing the time required to produce a contraction

• increasing the amount of work during a set time period

What is muscular endurance?

the ability to perform low intensity repetitions and/or resist fatigue over a prolonged period of time

How do you increase muscular endurance?

muscle contractions with light loads using many repetitions or a sustained contraction for a prolonged time period (isometric)

What are the 3 guiding principles used to improve muscle performance in PT?

overload, reversibility, specificity

What is the principle of overload used for?

increase strength

What is overload?

working harder than what is normal for you

When strength training, what is needed to increase in order to improve strength?

amount of resistance (weight)

When training for endurance, what is needed to increase to improve endurance?

amount of time a contraction is sustained or the number of reps

Before even considering progressive overload, what is an important factor to remember?

think safety first!!

What are some critical decision to make when deciding how to overload the muscle?

1. What is the underlying pathology or condition? 

2. What stage of healing is the injury?

3. What are the impairments? (Loss of function)

4. Are age modifications needed for the patient?

5. Are there any comorbidities?

6. What are the patient’s goals?

What does the SAID Principe stand for?

Specific Adaptation to Imposed Demand

What is the purpose of the SAID Principle?

emphasize task specific exercises

What does the Reversibility Principle state?

strength and endurance increases in response to specific training are temporary unless used regularly for functional activities

When does detraining begin?

a week or two after you don’t exercise

If you completely stop training a muscle, how long will it take for training effects to be lost?

within 8 weeks

What are the 5 Physiological Muscular Adaptations to resistance exercise?

1. Neural Adaptations

2. Hypertrophy: Increase in muscle fiber SIZE

3. Vascular Adaptations

4. Muscle fiber type Adaptations?

5. Connective Tissue Adaptations

What is the initial rapid gain in strength from?

due to an increased neural activity, not adaptive changes in the muscles tissue

For neural adaptations, the increased recruitment of the number of motor units and increased rate of firing cause…?

motor learning and improved coordination

EMGs suggest there is little to no muscle fiber hypertrophy in the…?

first 4 weeks of exercise

What is muscle hypertrophy?

increase size of an individual muscle fiber that leads to increased strength usually by 4-8 weeks (possible 2 weeks w/ high intensity)

What causes muscle hypertrophy?

increase in protein (action & myosin) synthesis

What Type of muscle fibers increases in size more readily?

Type II muscle fibers increase in size more readily than Type 1

Where does the greatest increase in hypertrophy occur with?

high rep, moderate load- eccentric exercise

What does evidence state about muscle fiber type adaptions?

there is little to no evidence of type I or type II conversion under any training conditions in rehabilitation or fitness programs

In endurance training, the cardiovascular and respiratory fitness occur with…?

low intensity, high reps (volume) resistance exercises

What occurs to the capillary bed density in strength training?

they decrease because of the increased number of myofilaments per fiber

What occurs to the tendons and ligaments with resistance training?

tensile strength of tendons and ligaments increases

What occurs to the connective tissue with resistance training?

it thickens, supporting enlarged fibers

What occurs to the bone mineral density with weight bearing exercises?

it increases

What are some precautions with resistive exercise?

• Cardiovascular-  Avoid Valsalva maneuver

• Emphasize Exhalation during exertion

• Pain should not occur or get worse with exercise

• Avoid Fatigue- assess patient and adjust

• Avoid Overtraining

• Substitutions - assess stabilization and adjust amount of resistance if observed

• Medications - may have negative side effects

• Discontinue ther ex with excessive pain, dizziness, SOB

What are some contraindication for resistive exercise?

• Severe or excessive Pain

• Acute, Inflammation  

  • Isometrics are OK!

• Severe Cardiopulmonary Disease – need MD approval

• Conditions or Surgery with ROM or weight bearing limitations could limit the choice of exercise – need MD approval