Download Presentation Package

chapter
Performance-Enhancing Substances
9
PerformanceEnhancing
Substances
Jay R. Hoffman, PhD; CSCS,*D; FACSM; FNSCA
Jeffrey R. Stout, PhD, CSCS, FACSM, FISSN, FNSCA
Chapter Objectives
• Provide reliable information to athletes on
the risks and benefits of performanceenhancing substances.
• Evaluate advertising claims for over-thecounter supplements marketed for
performance benefits.
• Describe the current status of research on
performance-enhancing supplements.
Key Term
• ergogenic aid: Any substance, mechanical
aid, or training method that improves sport
performance; for the purposes of this chapter,
the term refers specifically to pharmacological
aids.
Section Outline
• Types of Performance-Enhancing
Substances
Key Point
• The distinction between a drug and a
dietary supplement is linked to FDA
approval for safety and effectiveness.
Types of PerformanceEnhancing Substances
• Definition of Products That Can Be Sold as
Dietary Supplements
– A product (other than tobacco) intended to
supplement the diet that contains one or more
of the following dietary ingredients:
•
•
•
•
A vitamin
A mineral
An herb or other botanical
An amino acid
(continued)
Types of PerformanceEnhancing Substances
• Definition of Products That Can Be Sold as
Dietary Supplements (continued)
– A product (other than tobacco) intended to
supplement the diet that contains one or more
of the following dietary ingredients:
• A dietary substance for use by humans to supplement
the diet by increasing the total dietary intake
• A concentrate, metabolite, constituent, or extract (or
combination of any ingredient identified above)
(continued)
Types of PerformanceEnhancing Substances
• Definition of Products That Can Be Sold as
Dietary Supplements (continued)
– The product must also be intended for ingestion and
cannot be advertised for use as a conventional food
or as the sole item within a meal or diet.
Section Outline
• Hormones
– Anabolic Steroids
• Dosing
• Who Uses Anabolic Steroids?
• Ergogenic Benefits
– Muscle Mass and Strength
– Athletic Performance
• Psychological Effects
• Adverse Effects
(continued)
Section Outline (continued)
• Hormones
–
–
–
–
Testosterone Precursors (Prohormones)
Human Chorionic Gonadotropin
Insulin
Human Growth Hormone
• Efficacy
• Adverse Effects
– Erythropoietin
– β-Adrenergic Agonists
– β-Blockers
Hormones
• Anabolic Steroids
– The synthetic (man-made) derivatives of the male
sex hormone, testosterone
Table 9.1
Hormones
• Anabolic Steroids
– Dosing
• Athletes typically use anabolic steroids in a “stacking”
regimen, in which they administer several different drugs
simultaneously.
• The potency of one anabolic agent may be enhanced when
it is consumed simultaneously with another anabolic agent.
(continued)
Hormones
• Anabolic Steroids
– Dosing (continued)
• Most users take anabolic steroids in a cyclic pattern,
meaning that they use the drugs for several weeks or
months and alternate these cycles with periods of
discontinued use.
• Often athletes administer the drugs in a pyramid (step-up)
pattern in which dosages are steadily increased over
several weeks. Toward the end of the cycle, the athlete
“steps down” to reduce the likelihood of negative side
effects.
Dose-Response Curve
• Figure 9.2 (next slide)
– Dose–response curve of anabolic steroids and
changes in lean body mass
Figure 9.2
Reprinted, by permission, from Hoffman, 2002.
Hormones
• Anabolic Steroids
– Who Uses Anabolic Steroids?
• Olympic athletes, professional athletes, collegiate athletes,
and high school athletes have been reported to use
steroids.
• Many users are not involved in sports; they use steroids to
improve appearance.
– Ergogenic Benefits
• Muscle Mass and Strength
– Increases in muscle protein synthesis with steroid use are
likely responsible for increases in lean body mass.
– Changes occur in both recreationally trained and competitive
athletes.
Fat-Free Mass
• Figure 9.3 (next slide)
– Changes in fat-free mass with anabolic steroid
administration (200 mg/week nandrolone decanoate
for eight weeks) and following drug cessation
– *p < .05
Figure 9.3
Adapted, by permission, from Van Marken Lichtenbelt et al., 2004.
Hormones
• Anabolic Steroids
– Ergogenic Benefits
• Athletic Performance
– The purported ergogenic benefits commonly attributed
to anabolic steroid use are increased muscle mass,
strength, and athletic performance, but these changes
depend on the training status of the individual.
Hormones
• Anabolic Steroids
– Psychological Effects
• Anabolic steroid use is associated with changes in
aggression, arousal, and irritability.
– Adverse Effects
• The medical problems related to anabolic steroids may be
somewhat overstated.
• Many of the side effects linked to abuse are reversible upon
cessation.
• Side effects differ between anabolic steroid use under
medical supervision and consuming many drugs at high
doses.
Table 9.2
Hormones
• Testosterone Precursors (Prohormones)
– Although performance changes may not occur with
prohormone use, athletes may be at higher risk for
experiencing adverse side effects similar to those
associated with anabolic steroid use.
Hormones
• Human Chorionic Gonadotropin
– When injected into men, HCG can increase
testicular testosterone production.
• Insulin
– Insulin increases protein synthesis, but the side
effect of hypoglycemia can be fatal.
Hormones
• Human Growth Hormone
– Efficacy
• There are no studies on the efficacy of HGH in athletic
populations.
• Anecdotal reports suggest impressive musculoskeletal
performance changes in athletes using HGH.
Key Point
• The anabolic potential of human growth
hormone (HGH) and its ability to reduce
body fat have contributed to the rise in
HGH use among athletes.
Hormones
• Human Growth Hormone
– Adverse Effects
• Although growth hormone used as replacement therapy
for people with growth hormone or IGF-I deficiency can
be effective and can have minimal adverse consequences,
the dosages that are likely used by athletes may pose a
significant risk for acromegaly.
Hormones
• Erythropoietin
– Injections of EPO are associated with elevations in both
hematocrit and hemoglobin.
– Health risks include increased risk of blood clotting, elevations
in systolic blood pressure, a compromised thermoregulatory
system, and dehydration during aerobic endurance events.
• β-Adrenergic Agonists
– β-adrenergic agonists can increase lean mass and decrease
stored fat.
• β-Blockers
– β-blockers reduce anxiety and tremors during performance.
Key Point
• More research is needed to examine the
effect of many ergogenic aids in athletic
populations. Athletes should not misconstrue a lack of scientific information as an
indication of safety.
Section Outline
• Dietary Supplements
– Essential Amino Acids
– β-Hydroxy-β-Methylbutyrate
– Nutritional Muscle Buffers
• β-Alanine
• Sodium Bicarbonate
• Sodium Citrate
– L-Carnitine
– Creatine
• Importance of Creatine to Exercise
• Creatine Supplementation
(continued)
Section Outline (continued)
• Dietary Supplements
– Creatine (continued)
• Ergogenic Benefits
• Body Mass Changes
• Adverse Effects
– Stimulants
• Caffeine
– Efficacy
– Adverse Effects
• Ephedrine
– Efficacy
– Adverse Effects
• Citrus Aurantium
Dietary Supplements
• The sport supplement industry throughout
the world has exploded, with more than 600
sport nutrition companies marketing over
4,000 products that produce annual sales of
more than $4 billion in the United States
alone.
Dietary Supplements
• Essential Amino Acids
– EAA can augment muscle protein synthesis in
healthy human subjects.
• β-Hydroxy-β-Methylbutyrate (HMB)
– It is believed that HMB has both anabolic and
lipolytic effects, but research is limited. Recent
studies do not support HMB supplementation in
resistance-trained athletes.
Dietary Supplements
• Nutritional Muscle Buffers
– β-Alanine
– Sodium Bicarbonate
– Sodium Citrate
• L-Carnitine
– Studies examining L-carnitine’s role as an ergogenic
aid for increasing lipid oxidation have not shown
clear efficacy.
– L-carnitine may enhance recovery from exercise.
Dietary Supplements
• Creatine
– Importance of Creatine to Exercise
• The ability to rapidly rephosphorylate ADP is dependent
upon the enzyme creatine kinase and the availability of
creatine phosphate (CP) within the muscle.
– Creatine Supplementation
• Creatine supplementation increases the creatine content of
muscles by approximately 20%, but there is a saturation
limit.
– Ergogenic Benefits
• Studies consistently show significant ergogenic benefits.
Key Point
• Creatine, in the form of creatine phosphate
(CP; also called phosphocreatine [PCr]), has
an essential role in energy metabolism as a
substrate for the formation of adenosine
triphosphate by rephosphorylating adenosine diphosphate (ADP), especially during
short-duration, high-intensity exercise.
1RM Squat Strength
• Figure 9.4 (next slide)
– Changes in 1RM squat strength in experienced
collegiate American football players ingesting
creatine, creatine plus β-alanine, or a placebo
– * = significantly different (p < .05) compared to
placebo
Figure 9.4
Adapted, by permission, from Hoffman et al., 2006.
Key Point
• Creatine supplementation has been shown
to increase strength and improve training
by reducing fatigue and enhancing
postworkout recovery.
Dietary Supplements
• Creatine
– Body Mass Changes
• Prolonged creatine supplementation has been generally
associated with increases in body weight, especially
increases in fat-free mass.
– Adverse Effects
• Controlled studies have been unable to document any
significant side effects from creatine supplementation.
• Concerns include gastrointestinal disturbances and strain
on the kidneys.
Dietary Supplements
• Stimulants
– Caffeine
• Efficacy
– Increases time to exhaustion
– Effects on sprint or power performance unclear
• Adverse Effects
– Many adverse effects, including anxiety, gastrointestinal
disturbances, restlessness, insomnia, tremors, heart
arrhythmias, and increased risk for heat illness
– Is physically addicting
Key Point
• A central nervous system stimulant, caffeine
is an ergogenic aid that may enhance performance in aerobic and anaerobic athletes
alike.
Dietary Supplements
• Stimulants
– Ephedrine
• Efficacy
– Effective only when it is taken in combination with caffeine
– Improves aerobic endurance performance
• Adverse Effects
– Many adverse effects, including death
– Banned by most sport governing bodies, including the
International Olympic Committee
Dietary Supplements
• Stimulants
– Citrus Aurantium
• Is thought to contribute to appetite suppression, increased
metabolic rate, and lipolysis
• When combined with caffeine and other herbal products,
significant improvements in time to fatigue have been
reported
• On NCAA list of banned performance-enhancing drugs