Understanding Muscle Physiology and Fitness Principles

Muscles make up ____% of person’s body mass

40%

Muscle fiber

Single muscle cell.

Hypertrophy

Increase in size of muscle fiber.

Atrophy

Decrease in size of muscle fiber.

Slow-twitch fibers

Red muscle fibers that are fatigue-resistant but less powerful, used for long duration, endurance activities.

Fast-twitch fibers

White muscle fibers that contract rapidly and forcefully but fatigue quickly, used for actions that require strength, power, or speed.

Tendon

Connects muscle to a bone (strain).

Ligament

Connects bone to bone (sprain).

Muscles

Move the body and enable it to exert force.

When a muscle contracts (shortens), it…

moves a bone by pulling on the tendon that attaches the muscle to the bone.

Strength training helps

prevent and manage cardiovascular disease and diabetes

Repetition maximum

Maximum amount of resistance that can be moved a specified number of times.

assessing muscular endurance

Count the maximum number of repetitions of an exercise.

Power

Ability to exert force rapidly.

Static (isometric) exercise

Involves a muscle contraction without a change in the muscle length.

Isotonic (dynamic) exercise

Involves a muscle contraction with a change in the muscle length.

Concentric muscle contraction

Muscle gets shorter as it contracts (causes movement).

Eccentric muscle contraction

Muscle lengthens as it contracts (controls movement).

Constant resistance exercise

Load stays constant throughout a joint's entire range of motion (e.g. free weights, body weight).

Variable resistance exercise

Uses a changing or variable load throughout the joint's entire ROM (e.g. machine weights).

Plyometrics

Rapid stretching of a muscle group that is undergoing eccentric stress, followed by a rapid concentric contraction (e.g. box jumps).

FITT Principle

Frequency, intensity, time, type; recommends a minimum of 2 or more non-consecutive days/week of lifting.

Intensity

Resistance- amount of weight lifted determines the way the body adapts.

Failure

Leave 1-2 reps in the tank

Strength training

Low to moderate reps (1-5), moderate to high resistance (60-100% of 1 rep max) 'heavy weights, a few times'

training for endurance

Moderate to high reps (15-20), low to moderate resistance, 'lighter weights, more reps'

Hypertrophy

increase in size of muscle fiber

Reps

Number of times an exercise is performed during 1 set

Set

Group of reps followed by rest (1-3 sets is common)

Heavy weights

Rest 3-5 mins between sets

Low to moderate weights

Rest 1-3 mins between sets

Flexibility

The ability of a joint to move through its normal, full range of motion

Range of motion

Full motion possible in a joint

Static flexibility

Ability to hold an extended position at one end or point in a joint's range of motion

Dynamic flexibility

Ability to move a joint through its range of motion with little resistance

Benefits of stretching

Relief of aches and pains, muscle cramps, improved blood vessel health

Gonionmeters

used to measure each joint's range of motion

FITT principle

Goal: attain adequate flexibility in major joints

Static stretching

Stretch a muscle slowly and gently and hold in a stretched position

Dynamic stretching

Muscles are stretched by moving joints slowly and fluidly through their ROM in a controlled manner

PNF

a type of stretching where you contract and then relax

Low-back pain

Affects more than 85% of Americans by age 50; second most common ailment in the U.S.

Essential fat

Fats that are critical for normal body functioning; 3-5% of total body weight in men, 8-12% in women

Adipose tissue

Tissue in which fat is stored in fat cells under the skin or around organs

Percent body fat

The % of total body weight that is composed of fat

Obesity

More severe degree of overweight; prevalence increased from 13% in 1960 to about 42% today

Type 2 Diabetes

A disease that interferes with glucose metabolism

Metabolism

Process by which food energy and nutrients are made available to and used by the body

Resting metabolic rate (RMR)

Energy required (in calories) to maintain vital body functions while the body is at rest

Energy balance

Balance between energy intake and energy expenditure

Body mass index

Measure of relative body weight

Energy density

Calories per ounce or gram of food

1 pound of fat

3500 calories

Negative energy balance

You expend more calories than you take in (weight loss)