Training, The Environment, & Ergonomic Aids

Chapter 15

Exercise Physiology

Thermoregulation

• Basics• Cold Stress• Heat Stress• Heat Dissipating Mechanisms• Clothing• Exercise in Heat• Sweating• Heat Tolerance• Cold Tolerance

Basics-1• Body temp fluctuates throughout the day• Lower in sleep; higher when awake- even during

“lazing”• Tcore = Core Temperature

– Eardrum, rectum, esophagus– Estimate the temperature of the hypothalamus

• Oral Temperature is 1F less than rectal temperature

• The body can tolerate a core temperature can drop 18F, but only increase 5F.

Basics-2• Tskin = Shell Temperature

– Arm, trunk, leg, head, etc.• Tbody = Mean Body Temperature (est. of

avg. core temp– Tbody = (0.6 x Tcore) + (0.4 x Tskin)

• Hypothalamus= central coordinating center for temperature regulation; cannot “shut off” the heat– Thermal Receptors– Temperature changes in the blood

Cold Stress• When at rest in extreme

cold:– Reduce heat loss– Increase heat production

• Physiological Adaptations– Vascular Constriction– Muscular Activity– Hormonal Output

(epinephrine & norepinephrine increase heat production; prolonged exposure releases thyroxine to elevate resting metabolism)

Heat Stress• Without thermoregulation,

CBT could increase 1.8F per minute in intense, sustained exercise (4min=bad)

• Mechanisms– Radiation– Conduction– Convection– Evaporation

Heat Dissipating Mechanisms

• Circulatory System- Workhorse– Blood to skin for

convection, conduction, radiation, & evaporation

– Sweating begins seconds after vigorous exercise; after 30 min an equilibrium is established

– Hormonal adjustments to conserve salts (aldosterone) & fluid lost in sweating (ADH; vasopressin)

Clothing• Cold-

– Several layers or layers with fur, feathers, or synthetic fabrics

– Wet clothing loses 90% of insulating qualities; heat moves away from the body faster since H2O conducts heat faster than air

• Heat-– Loose fitting or moisture

wicking fabrics– Light colors to help

evaporate sweat & reflect heat

Exercise in Heat

• Circulatory system competes:– Increase BF to active muscles – Increase BF to skin to dissipate heat

• Sweating reduces blood plasma volume which decreases SV and increases HR

• Max cardiac output & aerobic capacity decreases in heat exercise since increased HR isn’t offset by decreased SV

• Core temp should increase in exercise; shows optimal physical functioning

Sweating• Blood plasma supplies most of sweat• Diuretics & laxatives or vomiting = dehydration• If left on their own, athletes only replace ½ of

H2O lost during exercise • Dehydration

– Increases systemic resistance to maintain BP– Decreases BF to skin which decreases heat

dissipation• Dehydration in cold weather

– Cold air has less moisture– Fluids used to humidify & warm incoming air– Cold increases urine production– Overdressing = more sweating

Heat Tolerance• Heat acclimatization- physiologic changes that

increase heat tolerance– First sessions in heat should be light intensity & only

15-20 minutes– Benefits dissipate after 2-3 weeks in regular

temperatures– Exercise in actual heat increases acclimatization and

is more beneficial than simulated heat exercise• Excess body fat makes it harder to regulate

temperature in heat because:– Fat is warmer than muscle– Fat insulates/holds more heat; prevents dissipation– Smaller body surface area to mass ratio= decreased

evaporation• Heat Stress Index p. 535

Cold Tolerance

• Wind Chill Index p. 536

• Cold air does not damage respiratory tract

Altitude

Barometric pressure

Dalton’s Law of Partial Pressure

Matt Carpenter Video 

Oxygen & Blood

Adjustments to High Altitude

ERGOGENIC AIDS

Barometric Pressure•is the force that is exerted on objects by the weight of the atmosphere above them.•the air above us and around us does weigh down on us.•is measured in terms of the downward force that the atmosphere exerts per unit of a certain area.•Higher elevations have lesser atmospheric pressure because they simply have less atmosphere above them. In lower elevations, of course, the opposite is true.•if it did not exist, then the atmosphere wouldn't either. •the downward force of barometric pressure is part of what causes water to boil. The less pressure there is, the more heat energy is required.

Dalton’s Law of Partial Pressure

•Dalton proposed that for a mixture of gases in a container, the total pressure exerted is the sum of the pressures hat each gas would exert if it were alone.•The pressure each gas exerts in a mixture of gases is called its Partial Pressure.•Ptotal = P1 + P2 + P3

Matt Carpenter Video

• http://video.nytimes.com/video/2009/02/23/sports/othersports/1194837978491/high-altitude-dominance.html

• The percentage of those molecules that are oxygen is exactly the same: 21%. The problem is that there are fewer molecules of everything present, including oxygen.

Oxygen & Blood•Hemoglobin increases at high altitude. High altitude causes oxygen to bind less tightly to hemoglobin, so that less is taken up in the lungs.•Physiological Shunt: blood that goes through lungs w/o picking up O2•Hypoxic pulmonary vasoconstriction (response to physiological shunt) blood vessels tighten so less deoxygenated blood can get through the lungs. •At high altitude, there is less oxygen in the air that you breathe, so all areas of the lungs are hypoxic.•Unfortunately, the lungs still respond to the shortage of oxygen in the same way: by tightening the blood vessels. 

Adjustments to High Altitude

Immediate• Hyperventilation

(reduce CO2)• Body fluids more alkaline

(b/c of hyperventilation)• Increase HR

Long-term• Hyperventilation• Excretion of bases• Increased HR• Cardiac output reduced• Reduced stroke volume• Increased hemoglobin• Increased capillarization of

skeletal muscle• Increased mitochondria• Increased aerobic enzymes

Ergogenic Aids

Ergogenic History

Ergogenic Prevalence

Ergogenic Basics

Source: “Use of Ergogenic Aids” by Athletes, by Marc D. Silver, MD

Ergogenic History

• 776BC first Olympic games (Greece)• 1889 French Physiologist reverse aging

with testicular extract injection• 1935 Testosterone synthesized• 1940’s Athletes take anabolic steroids• 1960’s- IOC bans steroids• 1968- Formal drug tests @ Olympics• 1988- Ben Johnson stripped of gold medal

Ergogenic Prevalence• Anabolic steroids

– Teens 11% boys & 2.5% girls– HS seniors started @ 16yo or younger– Adults 15% (self-report); higher in men– mostly cosmetic use by non-competitive

• 13,914 collegiate – creatine (13%)– amino acid supplements (8%) – dehydroepiandrosterone (DHEA)- a precursor to

testosterone and estrogen (1%)

Ergogenic Basics

Any means of enhancing energy production and utilization. Five categories:

1. Mechanical aids

2. Psychological aids

3. Physiologic aids

4. Pharmacologic aids

5. Nutritional aids

EXAMPLES

Ergogenic Examples

Any means of enhancing energy production and utilization. Five categories:

1. Mechanical aids- lightweight racing shoes

2. Psychological aids- hypnosis

3. Physiologic aids- blood doping ***

4. Pharmacologic aids- steroid supplements

5. Nutritional aids- creatine supplements

PHYSIOLOGIC AIDS

Physiologic Aids

Blood Doping

• http://www.youtube.com/watch?v=kDTxb3gzKFE (1:39)

• http://www.youtube.com/watch?v=XQQmK0g7v_0 (7:38)

• http://www.youtube.com/watch?v=ei2jr7nQcvg (5:15)

Hypoxic Training

• http://www.youtube.com/watch?v=fQTepZQe9O8 (1:48)

• http://www.youtube.com/watch?v=i7oEKp2E7Uc (2:26)

• http://www.hypoxico.com/Altitude-Training-Rentals.shtml (site)

HAPPY SPRING BREAK!•Online tests reopened for ½ credit. Must email me your new scores.•Online test for this chapter open until Tuesday, March 15th