15

Ergogenic Aids and Sport

chapter

Learning Objectives

• Review various substances that have been proposed to be ergogenic aids—substances or phenomena that enhance performance

• Learn the importance of including control groups and placebos when studying the ergogenic properties of a substance

(continued)

Learning Objectives (continued)

• Find out the proposed ergogenic benefits, proven effects, and risks of several pharmacological, hormonal, physiological, and nutritional agents

• Discover which substances that have been considered ergogenic are actually ergolytic—that is, they impair performance

Ergogenic vs. Ergolytic

Ergogenic aid: any substance or phenomenon that enhances performance

Ergolytic agent: any substance or phenomenon that has detrimental effects on performance

Researching Ergogenic Aids

Placebo effect: An effect produced by the subject’s expectations after administration of an inactive substance (placebo)

The Placebo Effecton 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

Sympathomimetic Amines: Amphetamines

• Central nervous system stimulants• Examples: ephedrine and pseudoephedrine• Proposed benefits:

– Increased concentration and mental alertness (state of euphoria)

– Decreased sense of mental fatigue– Enhanced athletic performance (speed, strength,

fatigue resistance)

Proven Effects and Risksof Sympathomimetic Amines

Proven effects• Weight loss• Reaction time, acceleration,

and speed• Strength, power, and

muscular endurance• Possibly aerobic endurance• Higher maximum heart rates

and peak lactate concentrations at exhaustion

• Better focus• Fine motor coordination

Risks• Death• Cardiac arrhythmias• Delay the sensation of fatigue• Extreme nervousness• Aggressive behavior• Insomnia

Beta-Blockers

• Prevent the binding of norepinephrine and decrease the effects of the sympathetic nervous system

• Proposed benefits: may improve accuracy (for shooting sports), decreased anxiety

• Proven effects: decrease maximum and submaximal heart rate and improve scores in shooting sports

• Risks: bradycardia, heart block, hypotension, bronchospasm, hypoglycemia, fatigue, and decreased motivation

Caffeine

• CNS stimulant; effects are similar to amphetamines• Proposed benefits:

– Increased mental alertness, concentration, reaction time, and energy level

– Reduced fatigue– Increased mobilization and use of FFA

Proven Effects and Risks of Caffeine

Proven effects• ↑ Mental alertness• ↑ Concentration• Elevated mood• ↓ Fatigue and delayed

onset• ↓ Reaction time• ↑ Catecholamine release• ↑ FFA mobilization• ↑ Use of muscle

triglycerides

Risks• Nervousness• Restlessness• Insomnia• Headache• Gastrointestinal problems• Tremors• Dehydration

Diuretics

• Increase urine production and excretion• Used for weight reduction and to mask other drugs

during drug testing

Proven Effects and Risks of Diuretics

Proven effects• Significant temporary

weight loss• ↓ Aerobic capacity

Risks• ↓ Thermoregulation• Electrolyte

imbalances• Fatigue• Muscle cramping• Exhaustion• Cardiac arrhythmias• Cardiac arrest

Hormonal Agents

• Anabolic steroids• Human growth hormone

Anabolic Steroids

• Are nearly identical to male sex hormones; synthetic form maximizes building effects

• Proposed ergogenic benefits– ↑ Fat-free mass and strength– ↑ Recovery from exhaustive training bouts

Proven Effects and Risksof Anabolic Steroids

Proven effects• ↑ Body mass and fat-free

mass• ↑ Total body potassium and

nitrogen• ↑ Muscle size• ↑ Strength

Risks• Testicular atrophy• Reduced sperm count• Prostate and breast

enlargement in men• Breast regression,

masculinization, and menstrual cycle disruption in women

• Personality changes• Liver damage• Cardiovascular disease

Percent Changes in Body Size, Body Composition, and Strength When Athletes

Used Anabolic Steroids and a Placebo

Adapted from G.R. Hervey et al., 1981, “Effects of methandienone on the performance and body composition of men undergoing athletic training,” Clinical Science 60: 457-461.

Relationship Between Total Doseof 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.

Changes in Fat-Free Mass and Quadriceps and Triceps Muscle Areas From MRI, and

Changes in Strength

Reprinted, by permission, from S. Bhasin et al., 1996, “The effects of supraphysiologic doses of testosterone on muscle size and strength in normal men,” New England Journal of Medicine 335: 1-7. Copyright © 1996 Massachusetts Medical Society. All rights reserved.

Human Growth Hormone

• Secreted naturally by pituitary; synthetic form used by some athletes

• Proposed ergogenic benefits:– Stimulation of protein synthesis in skeletal muscle– Stimulation of bone growth (if growth plates are not

yet fused)– Increased insulin-like growth factor synthesis– Increased lipolysis– Increased blood glucose– Enhancement of healing after musculoskeletal injury

Proven Effects and Risksof Growth Hormone

Proven effects (only in men > 60 years old)• ↑ Fat-free mass • ↓ Fat mass• ↑ Bone density

Risks• Acromegaly• Cardiomyopathy• Glucose intolerance• Diabetes• Hypertension

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)

• Proposed ergogenic benefits– 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

.

Proven Effects and Risksof Blood Doping

Proven effects• ↑ Maximal oxygen

uptake• ↑ Time to exhaustion• ↑ Performance time in

endurance events

Risks• ↑ Blood viscosity• Blood clotting• Heart failure• Blood matching errors• Hepatitis • HIV

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 (Dubuque, IA: Brown & Benchmark), 213-242. Copyright 1991 Cooper Publishing Group, Carmel, IN.

Erythropoietin (EPO)

• Natural hormone produced by the kidneys to stimulate red blood cell production

• Human EPO can be cloned and administered to increase red blood cell volume

• Proposed ergogenic benefits– Increases oxygen-carrying capacity of the blood

Proven Effects and Risks of EPO

Proven effects• ↑ Hemoglobin

concentration• ↑ Hematocrit

• ↑ VO2max

• ↑ Treadmill time

Risks• ↑ Blood viscosity• Thrombosis• Myocardial infarction• Congestive heart failure• Hypertension • Stroke• Pulmonary embolism

.

Oxygen Supplementation

• Breathed by athletes to increase oxygen content of blood

• Proposed ergogenic benefits:– Compete at higher intensities– Fend off fatigue– Speed recovery between exercise bouts

Proven Effects and Risksof Oxygen Supplementation

Proven effects• Breathing O2 during the

event enhances performance

• ↓ Peak blood lactate concentrations

Risks• No known serious risks

• O2 is flammable

Bicarbonate

• Natural part of body’s buffering system to maintain normal pH

• Proposed ergogenic benefits:– ↑ Blood pH, allowing higher concentrations of lactate

in the blood– Delays the onset of fatigue

Proven Effects and Risksof Bicarbonate Loading

Proven effects• Ingesting 300 mg per kg

body weight can increase performance in all-out exercise bouts between 1 and 7 minutes

Risks• Gastrointestinal

cramping• Bloating• 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–base 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, improving cardiovascular and metabolic function

• Proposed ergogenic benefits:– Increased potential for oxidative phosphorylation and

PCr synthesis– Enhanced 2,3-diphosphoglycerate synthesis in red

blood cells– Improved oxygen unloading from hemoglobin in the

active muscle– Improved buffering capacity– Improved endurance capacity

Proven Effects and Risksof Phosphate Loading

Proven effects• Improvements in VO2max

• ↑ Time to exhaustion• Results from studies are

divided

Risks• No known risks

.

Nutritional Agents

• Amino acids• L-carnitine• Creatine

Amino Acids

• L-tryptophan and branched-chain amino acids (BCAA) including leucine, isoleucine, and valine

• Proposed benefits include increasing 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: 789-794.

.

Creatine: ACSM Position Stand

• Can increase muscle PCr content, but not in all individuals

• The combination of creatine with large amounts of CHO might increase muscle uptake of creatine

• Exercise performance in short periods of intense, high power output activity can be enhanced, particularly with repeated bouts

• Maximal isometric strength, rate of maximal force production, and aerobic capacity are not enhanced by creatine supplementation

(continued)

Creatine: ACSM Position Stand (continued)

• Leads to weight gain within the first few days, likely attributable to water accumulation with creatine uptake in the muscle

• Combined with resistance training, creatine supplementation is associated with greater gains in strength and possibly associated with increased ability to train at higher intensities

• The high expectations for performance enhancement exceed the true ergogenic benefits