Transcript Presentation Package - faculty.coe.unt.edu

chapter
15
Ergogenic Aids
and Sport
Did You Know . . . ?
The placebo effect refers to when your body’s
expectations of a substance determine your body’s
response to it. While the effect is psychological in
origin, the body’s physical response to the substance
is real.
The Placebo Effect on Muscular
Strength Gains
Data from G. Ariel and W. Saville, 1972, "Anabolic steroids: The physiological effects of placebos,"
Medicine and Science in Sports and Exercise 4: 124-126.
Pharmacological Agents
Sympathomimetic amines
Beta-blockers
Caffeine
Diuretics
Recreationally used drugs
Amphetamines
• Increase mental alertness, blood pressure, heart rate,
blood glucose and FFA levels, and muscle tension
• Decrease sense of fatigue
• Redistribute blood flow to skeletal muscles
• May enhance speed, power, endurance, concentration,
and fine motor coordination
• May be addictive and can trigger cardiac arrhythmia or
death
Beta-Blockers
• Prevent the binding of norepinephrine and decrease
sympathetic nervous system activity
• May improve accuracy (for shooting sports)
• Decrease aerobic capacity but have no effect on
strength, power, or muscular endurance
• Prolonged use can cause bradycardia, heart blockage,
hypotension, bronchospasm, fatigue, and decreased
motivation
Caffeine
• Increases mental alertness, concentration,
catecholamine release, and mobilization and use of
FFA by the muscles
• Decreases fatigue and lowers perception of effort
• Improves endurance performance; may improve sprint
and strength performance
• Can cause nervousness, insomnia, and tremors and
can lead to dehydration
Diuretics
• Increase urine production and excretion
• Used for weight reduction and to mask other drugs
during drug testing
• Cause weight loss (water loss)
• Can lead to dehydration, impaired thermoregulation,
and electrolyte imbalances
Hormonal Agents
• Anabolic steroids
• Human growth hormone
• Oral contraceptives
Anabolic Steroids
• Are nearly identical to male sex hormones; synthetic
form maximizes building effects
• Increase muscle mass and strength
• Can cause testicular atrophy, reduced sperm count,
and prostate and breast enlargement in men
• Can cause breast regression, masculinization, and
menstrual disruption in women
• Cause personality changes, liver damage, and
cardiovascular disease
Percent Changes in Body Size, Body
Composition, and Strength When Athletes
Used Anabolic Steroids and a Placebo
Relationship Between Total Dose of
Steroid and Change in Fat-Free Mass
(in kg)
From an article published in Metabolism, vol. 34, G.B. Forbes, "The effect of anabolic steroids on lean body
mass: The dose response curve," pp. 271-573, Copyright 1985.
STEROIDS AND STRENGTH GAINS
Human Growth Hormone
• Secreted naturally by pituitary; synthetic form used by
some athletes
• Difficult to detect synthetic from natural in drug testing
• Proven to increase lipolysis and blood glucose levels
• Can cause acromegaly, enlargement of internal organs,
muscle and joint weakness, diabetes, hypertension,
and heart disease
Physiological Agents
•
•
•
•
•
Blood doping
Erythropoietin
Oxygen supplementation
Bicarbonate loading
Phosphate loading
Blood Doping
• Artificial increase in total volume of red blood cells
(often via transfusion)
• Improves endurance performance by increasing blood’s
O2-carrying capacity
.
• Increases VO2max, time to exhaustion, and measurable
performance
• Can cause blood clotting, heart failure, and transfusion
complications
.
Changes in VO2max and Running Time to
Exhaustion After Reinfusion
of Red Blood Cells
Adapted, by permission, from F.J. Buick et al, 1980, "Effect of induced erythrocythemia on aerobic work
capacity," Journal of Applied Physiology 48: 636-642.
Improvements in Running Times After
Reinfusion of Red Blood Cells
Adapted, by permission, from L.L. Spriet, 1991, Blood doping and oxygen transport. In Ergogenics Enhancement of performance in exercise and sport, edited by D.R. Lamb and M.H. Williams (Dubugue, IA:
Brown & Benchmark), 213-242. Copyright 1991 Cooper Publishing Group, Carmel, IN.
Erythropoietin
• Natural hormone produced by the kidneys to stimulate
red blood cell production
• Can be cloned and administered to increase red blood
cell volume
.
• Increases VO2max and time to exhaustion
• Can cause blood clotting and heart failure due to
increased blood viscosity
Oxygen Supplementation
• Breathed by athletes to increase oxygen content of
blood
• Can improve performance if administered during
exercise, but not before or after
• Too cumbersome to be practical
• No serious risks known
OXYGEN SUPPLEMENTATION AND
PERFORMANCE
Bicarbonate
• Naturally part of body’s buffering system to maintain
normal pH
• Loading increases blood alkalinity so that more lactate
can be cleared (delay fatigue)
• Ingesting 300 mg per kg body weight can increase
performance in all-out exercise bouts between 1 and 7
minutes
• Can cause gastrointestinal cramping, bloating, and
diarrhea
Concentrations of (a) Blood Bicarbonate
and (b) Blood Hydrogen Ion With and
Without Ingestion of Sodium Bicarbonate
Adapted, by permission, from D.L. Costill et al., 1984, "Acid-based balance during repeated bouts of
exercise: Influence of HCO3," International Journal of Sports Medicine 5: 228-231.
Phosphate
Loading is thought to increase phosphate levels
throughout the body, which then
• increase potential for oxidative phosphorylation and
PCr synthesis,
• enhance oxygen release to the cells, and
• improve cardiovascular response to exercise and
buffering and endurance capacities.
Studies are divided on results of phosphate loading.
No risks are yet known.
Nutritional Agents
• Amino acids
• L-carnitine
• Creatine
Amino Acids
• L-tryptophan and BCAA
• Proposed to increase endurance performance
by delaying fatigue
• Studies are inconclusive on effects on
performance
Time to Exhaustion on .a Cycle
Ergometer at 70% of VO2max
Adapted, by permission, from G. van Hall et al., 1995, "Ingestion of branched-chain amino acids and
tryptophan during sustained exercise in man: Failure to affect performance," Journal of Physiology 486: 789794.
Creatine
• Supplement to better maintain muscle ATP levels
• Shown to increase strength and possibly fat-free body
mass
• Not shown to help endurance performance, sprint
running, or sprint swimming performance