FTCE 6.7

Determine how human body systems adapt to physical activity.

Muscle Fiber Types

• Slow Twitch– Type I

• Fast Twitch– Type II

Table 2.2 Relative Involvement of Muscle Fiber Types in Sport Events

Event Type I Type II

100-m sprint Low High

800-m run High High

Marathon High Low

Olympic weightlifting Low High

Barbell squat High High

Soccer High High

Field hockey High High

Football wide receiver Low High

Football lineman High High

Basketball Low High

Distance cycling High Low

Table 2.3 Major Adaptations to Resistance Versus Aerobic Endurance Training

Variable Resistance Aerobictraining endurance training

Size of muscle Increase No changefibers

Number of muscle No change No changefibers

Movement speed Increase No change

Strength Increase No change

Aerobic capacity No change Increase

Anaerobic capacity Increase No change

Adaptations to resistance training are specific to the

type of exercise performed.

Although aerobic endurance training increases

aerobic power, it does not enhance muscle strength or

size. In fact, intense aerobic endurance training can

actually compromise the benefits of resistance training.

Table 4.1 Exercise Prescription Guidelines for Stimulating Bone Growth

Variables Specific recommendations

Volume 3-6 sets of up to 10 repetitions

Load 1-10RM

Rest 1-4 min

Variation Typical periodization schemes designed to increase muscle strength and size

Exercise selection Structural exercises: squats, cleans, deadlifts, bench presses,

shoulder presses

The components of mechanical load that stimulate

bone growth are the magnitude of the load (intensity),

rate (speed) of loading, direction of the forces, and

volume of loading (number of repetitions).

The process of hypertrophy involves both an

increase in the synthesis of the contractile proteins actin

and myosin within the myofibril and an increase in the

number of myofibrils within a muscle fiber. The new

myofilaments are added to the external layers of the

myofibril, resulting in an increase in its diameter.

Stimulating Muscular Adaptations

For strength: high loads, few repetitions, full recovery periods

For muscle size: moderate loads, high volume, short to moderate rest periods

For muscular endurance: low intensity, high volume, little recovery allowed

Table 4.2 Proportion of Type II Fibers in Athletes Who Perform Anaerobic Activities

Type of athlete Type II fibers

Bodybuilders 44%

Javelin throwers 50%

800-m runners 52%

Weightlifters 60%

Shot-putters 62%

Discus throwers 63%

Sprinters and 63% jumpers

A general connective tissue

response to aerobic endurance exercise

is increased collagen metabolism.

It has been theorized that the endocrine system can be manipulated naturally with resistance training to enhance the development of various target tissues, thereby improving performance.

Endocrine Glands of the BodyEndocrine Glands of the Body

The force produced in the activated fibers stimulates

receptor and membrane sensitivities to anabolic factors,

including hormones, which lead to muscle growth and

strength changes.

Hormone responses are tightly linked

to the characteristics of the resistance

exercise protocol.

Large-muscle group exercises result in

acute increased serum total testosterone

concentrations in men.

Growth hormone is important for a child’s normal

development and appears to play a vital role in adapting

to the stress of resistance training. However, GH

injections result in a wide variety of secondary effects

not related to changes in muscle size or strength and

can, in fact, result in hypertrophy with less force

production than results from exercise-induced

hypertrophy.

Training protocols must be varied to allow the

adrenal gland to engage in recovery processes and to

prevent the secondary responses of cortisol, which can

negatively affect the immune system and protein

stuctures.

Human Heart Structure and Blood FlowHuman Heart Structure and Blood Flow

Arterial and Venous Components of the Circulatory System

Arterial and Venous Components of the Circulatory System

The cardiovascular system transports nutrients and

removes waste products while helping to maintain the

environment for all the body’s functions. The blood

transports oxygen from the lungs to the tissues for use

in cellular metabolism; blood also transports carbon

dioxide—the most abundant by-product of metabolism

—from the tissues to the lungs, where it is removed

from the body.

The primary function of the

respiratory system is the basic exchange

of oxygen and carbon dioxide.

Acute aerobic exercise results in increased cardiac

output, stroke volume, heart rate, oxygen uptake,

systolic blood pressure, and blood flow to active muscles

and a decrease in diastolic blood pressure. Resistance

exercise with low intensity and high volume generally

results in similar responses, some to a lesser degree.

Acute bouts of high-intensity, low-volume resistance

exercise result in increased heart rate and increased

diastolic and systolic blood pressure but no change in

oxygen uptake, no change or a slight increase in cardiac

output, and no change or a slight decrease in stroke

volume.

During aerobic exercise, large amounts of oxygen

diffuse from the capillaries into the tissues, increased

levels of carbon dioxide move from the blood into the

alveoli, and minute ventilation increases to maintain

appropriate alveolar concentrations of these gases.

Aerobic exercise training results in increased

maximal cardiac output and maximal oxygen uptake,

slower resting heart rate, increased capillarization,

improved ventilation efficiency, increased oxygen

extraction, and OBLA occurring at a higher percentage of

aerobic capacity.