Transcript Pharmacological Agents

Ergogenic Aids and Sport
CHAPTER 16 Overview
• Researching ergogenic aids
• Pharmacological agents
• Hormonal agents
• Physiological agents
• Nutritional agents
Ergogenic Aids Introduction
• Ergogenic (“work producing”) versus
ergolytic (“work breaking”) substances
• Potential aids
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Pharmacological agents
Hormones
Physiological agents
Nutritional agents
Table 16.1
Table 16.1 (continued)
Researching Ergogenic Aids
• Must be proven to enhance performance
– Claim alone insufficient
– True ergogenic versus pseudoergogenic responses
• Placebo effect
– Placebo: inactive substance that looks like the real
thing
– Expectations affect physiological response
– Double-blind experimental design
Figure 16.1
Researching Ergogenic Aids
• Scientific results may not provide clear
answers to ergogenic questions
– May be able to prove ergogenic action
– Results often equivocal
• Factors that can limit research
– Technique, equipment inaccuracy
– Research methodology
– Testing situations (lab vs. field)
World Antidoping Code:
Criteria for Prohibited Substance
1. Substance or practice has the potential to
enhance sport performance
2. Substance or practice has the potential to
harm the athlete
3. Substance or practice violates the spirit of
sport
Pharmacological Agents
• Must know all drugs taken by the athlete
– Therapeutic use exemption in advance for certain
medical circumstances
– Otherwise athletes may forfeit medals, prizes,
awards
• Check drugs versus banned substances list
• Examples: sympathomimetic amines, bblockers, caffeine, diuretics, recreationally
used drugs
Pharmacological Agents:
Sympathomimetics
• Sympathomimetic amines
– Amphetamines (also ephedrine, pseudoephedrine)
– Medical and ergogenic applications
• Proposed benefits of amphetamines
– Weight loss
– Heighten concentration and focus
– Make athletes more competitive, induce sense of
being indestructible and euphoria
– Enhance performance, delay fatigue
Pharmacological Agents:
Sympathomimetics
• Proven effects of amphetamines
–  State of arousal, energy, self-confidence
–  Fatigue
–  HR, blood pressure, blood flow, blood glucose,
FFAs
• Enhance performance by
–  Weight loss
– Improving reaction time, speed, and focus
–  Strength, power
–  Max HR, peak lactate
Pharmacological Agents:
Sympathomimetics
• Risks of amphetamines, ephedrine
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Death, toxicity
Heatstroke, cardiac stress
Addiction (psychological, physiological)
Masking of physiological danger signals
• Ephedrine and pseudoephedrine lack
benefits but still carry significant risks
Pharmacological Agents:
b-blockers
• b-blockers reduce sympathetic effects
– Used to treat cardiovascular disease
– Also for migraines, anxiety, stage fright
• Proposed benefits of b-blockers
– Decrease performance anxiety
– Enhance physical steadiness
Pharmacological Agents:
b-blockers
• Proven effects of b-blockers
–  Resting, submaximal, and maximal HR
–  Hand stability
• Risks of b-blockers
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Bronchospasm in asthmatics
Cardiac failure, low blood pressure/dizziness
Hypoglycemia (type II diabetics)
Fatigue, impaired performance
Pharmacological Agents:
Caffeine
• Caffeine
– Central nervous system stimulant
– Sympathomimetic effects (but weaker)
• Proposed benefits of caffeine
–  Mental alertness, feel more competitive
– More energy, reduced or delayed fatigue
– Enhanced mobilization of FFAs
– Glycogen sparing
Pharmacological Agents:
Caffeine
• Proven effects of caffeine
–  Alertness, concentration, and mood
–  Fatigue and reaction time (faster response)
–  Fat metabolism
–  All types of performance
• Risks of caffeine
– Nervousness, tremors, insomnia
– Headache
– GI problems
Pharmacological Agents:
Diuretics
• Diuretic clinical uses
– Increase urine production to reduce body water
– Control hypertension, edema
• Proposed benefits of diuretics
– Weight control
– Dilute other banned substances in urine samples
Pharmacological Agents:
Diuretics
• Proven effects of diuretics
– Significant temporary weight loss
– Resulting dehydration is ergolytic
–  Plasma volume   Qmax   VO2max
• Risks of diuretics
– Impaired thermoregulation
– Electrolyte imbalance (including hyponatremia)
– Death
Pharmacological Agents:
Recreational Drugs
• Alcohol, cocaine, marijuana, nicotine
• No ergogenic effects
• Many ergolytic effects
• Alcohol + caffeine = ergolytic effects
Hormonal Agents:
Anabolic Steroids
• Anabolic steroid use
– Androgenic: similar to male sex hormones
– Enhances anabolic function (builds bone, muscle)
– Athletes have become good at avoiding detection
• Proposed benefits of anabolic steroids
– Increased fat-free mass (FFM), strength
– Reduced fat mass
– Facilitate recovery after exhaustive exercise
Hormonal Agents:
Anabolic Steroids
• Proven effects on muscle mass, strength
–  body mass, FFM
–  Fat mass
–  Total body potassium and nitrogen (FFM markers)
–  Muscle size, strength
• Dose threshold for anabolic effects
– Small doses ineffective
– Large, chronic doses very effective
Figure 16.2
Figure 16.3
Hormonal Agents:
Anabolic Steroids
• High-dose testosterone  same effects
–  FFM
–  Triceps and quadriceps area
–  Strength
• Muscle mass increase is dose dependent
–  Type I and type II cross-sectional area
–  Number of muscle fiber nuclei
Figure 16.4
Hormonal Agents:
Anabolic Steroids
• Proven effects on cardiorespiratory
endurance
–  Red blood cell production and total blood volume
– No effect on VO2max
• Proven effects on recovery from training
–  muscle fiber damage after exhaustive lifting
–  Rate of protein synthesis during recovery (rats)
Hormonal Agents:
Anabolic Steroids
• Issues with anabolic steroid use
– Moral and ethical concerns
– Fair competition (basis for World Anti-Doping Code)
• Sexual risks
– Men: early growth stoppage, supression of normal
hormones (testicular abnormalities), excess
estrogen (breast enlargement)
– Women: disrupted menstruation/ovulation,
development of masculine sex characteristics
Hormonal Agents:
Anabolic Steroids
• Cancer risks: prostate, liver
• Cardiovascular risks
– Cardiac hypertrophy, cardiomyopathy, heart attack
– Thrombosis, arrhythmia, hypertension
–  HDL,  LDL
Hormonal Agents:
Anabolic Steroids
• Emotional and psychological risks
–  Aggression (“roid rage”)
–  Violence
– Potential drug dependence
• Other risks
– Contracting hepatitis, HIV/AIDS
–  Life span (mice)
–  Incidence of birth defects
– Long-term effects of abuse unknown
Hormonal Agents:
Andro, DHEA
• Baseball steroids scandal
– Androstenedione (Mark McGwire) purported to
enhance testosterone production
– DHEA may enhance androstenedione, testosterone
• Studies generally show andro and DHEA
ineffective
– No significant strength gains
– Possible increase in estrogen
– Banned anabolic steroids more effective, popular
Hormonal Agents:
Human Growth Hormone
• Human growth hormone (hGH)
• Six proposed benefits of hGH use
– Stimulates protein, nucleic acid synthesis
– Stimulates bone growth (young athletes)
– Stimulates IGF-1 synthesis
–  FFA mobilization,  fat mass
–  Blood glucose levels
– Enhances healing after injury
Hormonal Agents:
Human Growth Hormone
• Proven effects of hGH use
–  Fat mass
– Young athletes: no anabolic effects
– Older men:  FFM,  bone density
• Risks of hGH use
– Acromegaly
– Cardiomyopathy, hypertension
– Glucose intolerance/diabetes
Physiological Agents
• Using any substance that occurs naturally
in body to improve performance
• Five major physiological agents
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Blood doping
Erythropoietin (EPO)
O2 supplementation
Bicarbonate loading
Phosphate loading
Physiological Agents:
Blood Doping
• Blood doping
– Any means by which red blood cell count increases
– Often through transfusion of previously donated red
blood cells
• Proposed benefits of blood doping
– Enhanced oxygen-carrying capacity
– Improved aerobic endurance and performance
• Proven effects of blood doping
–  VO2max (long term)
–  Aerobic endurance (short term)
Figure 16.5
Physiological Agents:
Blood Doping
• Maximizing benefits of blood doping
– Must reinfuse 900+ ml whole blood
– Must wait 5 to 6 weeks before reinfusion
– Must freeze (not refrigerate) stored blood
• Blood doping and endurance performance
– Enhances aerobic performance
– Benefit more evident in second half of race
Figure 16.6
Physiological Agents:
Blood Doping
• Risks of blood doping
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Blood becomes too viscous
Excessive clotting, heart failure
Some sports set hematocrit limits for competition
Blood matching complications
Exposure to bloodborne diseases
• Potential medical risks far outweigh
benefits
Physiological Agents:
EPO
• EPO slightly different from blood doping
– Natural kidney hormone
– Stimulates red blood cell production
• Proposed benefits of EPO
– Increased hematocrit
– Increased oxygen-carrying capacity
• Proven effects of EPO
–  Hemoglobin, hematocrit, and VO2max
–  Time to exhaustion
Physiological Agents:
EPO
• Risks of EPO use
– Dangerous increase in blood viscosity
– Blood clots, heart attack, heart failure, stroke
– Pulmonary embolism, hypertension
• Effects of EPO less predictable than those
of red blood cell reinfusion
Physiological Agents:
O2 Supplementation
• Proposed benefits of O2 supplementation
– Increase dissolved oxygen in blood
– Delay fatigue, speed recovery
• Proven effects of O2 supplementation
– Preexercise treatment  little or no effect
– During exercise   work, work rate, metabolic
efficiency,  peak blood lactate levels
– After exercise  no effect
Physiological Agents:
O2 Supplementation
• Risks of O2 supplementation
– No known risks
– Safety needs further research
– Oxygen equipment potentially dangerous
• Overall, simply not practical
Physiological Agents:
Bicarbonate Loading
• Proposed benefits of bicarbonate loading
– Increased blood pH and buffering capacity
– Delayed onset of anaerobic fatigue
• Proven effects of bicarbonate loading
– 300 mg/kg   all-out performance for 1 to 7 min
– Enhanced H+ removal from muscle fibers
• Risks of bicarbonate loading
– GI discomfort (bloating, cramping)
– Sodium citrate  similar results without risks
Figure 16.7
Physiological Agents:
Phosphate Loading
• Proposed benefits of phosphate loading
– Enhanced PCr resynthesis
– Enhanced oxidative phosphorylation
– Greater O2 unloading at muscle
• Proven effects of phosphate loading
– Findings equivocal
– Some studies no effects, others  V̇O2max and time
to exhaustion
• No known risks of phosphate loading
Nutritional Agents:
Amino Acids
• L-tryptophan
– Proposed effects: analgesic, delays fatigue
– Proven effects: no improvement
• Branched-chain amino acids (BCAAs)
– Proposed effects: delay fatigue
– Study showed no effect from  or  BCAAs
• HMB (leucine metabolite)
– Some evidence may  FFM, strength but unclear
– Decreases cholesterol, LDL, blood pressure
Figure 16.8
Nutritional Agents:
L-Carnitine
• Proposed benefits of L-carnitine
– Enhanced fatty acid oxidation
– Glycogen sparing
• Proven effects of L-carnitine
– Conflicting results
– Most findings negative
Nutritional Agents:
Creatine
• Creatine
– Widespread use (recreational to professional)
– Target: skeletal muscle
• Proposed benefits of creatine
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Increased muscle PCr content
Enhanced peak power production
Serves as buffer, helps regulate pH balance
Enhanced oxidative metabolic pathways
Nutritional Agents:
Creatine
• ACSM conclusions regarding creatine
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Enhances high-power-output activity
Maximal strength not affected
With resistance training  strength gains
Results do not live up to expectations
• Creatine + exercise =  FFM, strength
• May not improve performance
Nutritional Agents:
Contamination of Supplements
• Supplement marketing and labeling not
overseen by FDA
• Purity of supplements and accuracy of
supplement labels suspect
• Contamination with banned substances can
lead to disqualification, forfeit of medals