Strength and Power (healthy)

Strength

The ability of a muscle or muscle group to exert maximal force in a single effort

Power

The highest output attainable during a particular movement

What matters in terms of power

Speed

How can you assess strength

Dynamometry

How can you assess power

5 rep sit to stand

What are the two types of testing with a dynamometer

Make or Break

Make test

Involves the patient pushing as hard as possible into a stationary dynamometer

Break test

Involves the patient resisting as the force is increased against them

How will comfort impact readings

Less comfort will decrease value

What does further placement mean for lever arm

Increases lever arm

What does an increased lever arm do to the mechanical advantage

It increases the mechanical advantage

Why should you perform 3 dynamometer readings

First one tends to be confusing for patients
Allows more efforts to gauge responds

Reasonings for taking the average of 3 reps with dynamometry

Accounts for bets and worst efforts
Gives an overview of general strength during most tasks

Reasonings for taking the best rep with dynamometry

Only includes best effort
Gives insight into maximum capacity to generate force

Strength should be within what percentage for each side when using a dynamometer

~10%

What can a dynamometer reading help estimate

1 rep max

General benefits of resistance training

Possible improvement in capacity in ability to repair and heal soft tissue
Possible improvement in balance
Improved performance for ADLs, occupational tasks, and recreational tasks
Improved QoL
Positive changes in body composition

What type of exercise is resistance training

Active

What kind of muscle contraction is involved in resistance training

Dynamic or static

What provides resistance during resistance training

Outside force

What type of force is applied during resistance training

Manual or mechanical

What are the two types of energy systems

ATP-PC system
Anaerobic Glycolytic System

What are the main fuel sources for the ATP-PC system

Adenosine triphosphate (ATP)
Phosphocreatine (PC)

Where is the ATP-PC system stored

Muscle cells

What is the ATP-PC system fuel source

PC

Does the ATP-PC system have a small or large maximum capacity

Small

Does the ATP-PC system have a small or large maximum power

Large

In the ATP-PC system, what is the energy for

Short, quick bursts

Which part of activity is the ATP-PC system a major source for

The first 30 seconds

When does the ATP-PC system replenish

During rest

What is the fuel source for the anaerobic glycolytic system

Glycogen/Glucose

What are the products of the anaerobic glycolytic system

Resynthesized ATP
Lactic acid

Maximum capacity and power produced by anaerobic glycolytic system

Both intermediate

What is the energy produced in the anaerobic glycolytic system used for

Moderate intensity
Short duration

What part of the activity is the anaerobic glycolytic system used during

30-90 seconds

How does skeletal muscle respond to resistance training

Hypertrophy
Possible hyperplasia
Increased type IIA fibers (remodeling of type IIB)
Decreased mitochondrial density

How does the neural system respond to resistance training

Increased motor unit recruitment
Increased rate of firing (causing decrease in contraction time)
Increased synchronization of firing

How does the metabolic system respond to resistance training

Increased ATP/CP storage
Increased myoglobin storage
Increase in triglyceride storage

How does other tissue respond to resistance training

Increased thickness and tensile strength of tendons, ligaments, and connective tissue
Increased bone mineral density
Possible increase in bone mass

ACSM recommendation for resistance training: frequency

At least 2-3 times/week

ACSM recommendation for resistance training: intensity

At least 60%

ACSM recommendation for resistance training: time

1-4 sets
1-12 reps

ACSM recommendation for resistance training: type

Body weight
Free weights
Machines

ACSM recommendation for resistance training: endurance

Load: < 70% 1 rep max
Set/Rep: 2-4 sets, 10-25 reps
Rest: 30-60 seconds

ACSM recommendation for resistance training: strength (novice)

Load: 60-70% 1 rep max
Set/Rep: 1-3 sets, 8-12 reps
Rest: 1-3 minutes

ACSM recommendation for resistance training: strength (advanced)

Load: 80-100% 1 rep max
Set/Rep: 2-6 sets, 1-8 reps
Rest: 1-3 minutes

ACSM recommendation for resistance training: power

0-60% 1 rep max
Set/Rep: 1-3 sets, 3-6 reps
Rest: 1-3 minutes

What are the benefits of isometric contractions

Controlled positioning
Person specific resistance
Improved strength + or - 15 degrees of position where strengthening occurred

What are the limitations of isometric contractions

Potential increase in BP with valsalva maneuver
Limited ROM carryover

What are the benefits of concentric contractions

Looks like ADLs
Larger ROM used

What are the limitations of concentric contractions

Requires more motor control
May require equipment

What are the benefits of eccentric contractions

Higher loads can be used
Difficult parts of ADLs

What are the limitations of eccentric contractions

Most likely to result in DOMS
More coaching needed
Requires greater control of movement

In manually applied resistance where does the resistance come from

The PT

When can manually applied resistance be used

During isometric, concentric, and eccentric

What do you need for manually applied resistance

Good body mechanics

What are the advantages of manually applied resistance

Effective in early stages
Finely graded resistance
Controlled ROM
Easily adjusted

What are the disadvantages of manually applied resistance

Amount of load is limited
Speed is slow to moderate
Can’t be done without PT
Labor intensive for the PT
Impractical for muscular endurance due to time

Manually applied resistance guidelines

Stabilize proximal attachment of muscle
Apply force distal to moving segment
Hand placement to provide tactile cues

What are the strengths of body weight/gravity

No equipment isneeded

What are the limitations of body weight/gravity

Ability to change load

What are the strengths of free weights/simple pulleys

Ability to change position and work different muscle groups
Can be used for isotonic or isometric
Stabilizing muscle recruited
Constant load throughout range

What are the limitations of free weights/simple pulleys

Minimal stabilizing support provided externally
Need a variety of dumbbells/plates to change load
Constant load throughout range

What are the strengths of weight machines

Load varies throughout range
Specific in movement allowed to isolate muscle group(s)
External stabilization provided to patient
Ability to change load more easily

What are the limitations of weight machines

Specific in movement allowed
Translation of load to other pieces of equipment is difficult
Expensive
Space

What are the strengths of elastic resistance bands

Portable
Inexpensive
Versatility - not gravity dependent
Various speeds of movement allowed

What are the limitations of elastic resistance bands

Difficult to gauge true resistance
Elastic can fatigue
Allergies

Higher load causes ____ mechanical demand

More

Lower load causes ____ mechanical demand

Less

A larger arc of movement causes ____ mechanical demand

More

A smaller arc of movement causes ____ mechanical demand

Less

A longer lever arm causes ____ mechanical demand

More

A shorter lever arm causes ____ mechanical demand

Less

A higher speed causes _____ power needed

More

A slower speed causes ____ time under tension

More

A longer rest period allows for ____ recovery for strength and power

More

A shorter rest period allows for ____ recovery

Less

Shorter rest period are better for what

Endurance

What are the two autoregulated approaches to resistance training

RPE
Repetitions in reserve

RPE Goal

Lift a weight until desired RPE is felt

Rep goal

Lift weight that requires desired RPE to lift 1 time

What does reps in reserve estimate

How many more repetitions could have been completed
Typically want to get close to failure (<5 reps in reserve)