Transcript Seminar in Advanced Physiology of Exercise

New Yorker, Oct 9, 2000
Ergogenic aids fall into two categories:
 Physical / Verbal
– cheering, music, altitude training, sauna
and massage, psychology etc.
 Chemical and Pharmacological
– anabolic steroids, stimulants, narcotic
analgesics, beta blockers, diuretics, amino
acids, vitamins etc.
Ergogenic Aids: History of Use
 Ancient Greek Olympians ate mushrooms
 Aztec athletes ate human hearts
 In late 1800s, European cyclists took heroin, cocaine
"speedballs," and ether-soaked sugar tablets
 Winner of 1904 Olympic marathon took strychnine
and brandy during race
 Winner of 1920 Olympic 100-m dash drank sherry
with raw egg before race
 In 1960 Olympics, Danish cyclist died in road race
from amphetamine
 In 1967 Tour de France, famed British cyclist died,
also from amphetamine
 Olympic testing began in 1968 for stimulants
Ergogenic Aids: History of Use
 Development of Dianabol
 East German female
swimmers of 1970s-1980s
 Cyclists deaths (1987-1990)
 Chinese female swimmers
(1992-1994)
 1998 Tour de France
 27 Chinese athletes
removed from team
 Bulgarian and Romanian
weightlifting teams
expelled
 USATF relinquished
drug testing
– alleged >12 positive tests
not reported last 2 years
Desire to Win by Elite Athletes
A 1997 SI survey of elite US athletes asked whether
they would take an illegal drug that guaranteed an
Olympic gold medal.
 >90% would take it if assured of not being
caught
 >50% would take it even if side effects were
lethal in 5 years
Ergogenic Aids: Placebo Effect
Ariel & Savill, MSSE, 1972
Increasing Muscle Mass
 Anabolic
steroids
 Growth
hormone
 Protein
supplements
Anabolic Steroids
 Male hormones have anabolic effects
– accelerated growth of muscle, bone, and
red blood cells
 Anabolic steroids are synthetic relatives
to testosterone
– high-volume training needed for beneficial
effects
– inhibit protein breakdown
Anabolic Steroids: Secondary Effects
Androgenic effects
– males: testicular atrophy, breast
development,  sperm count, acne
– females: masculinization, facial & chest
hair growth, deepening of voice, acne
Additional effects
– aggressiveness, mood swings, altered
glucose metabolism, thyroid, lipid profiles
Commonly Used Anabolic Steroids





Testosterone
Stanazolol
Nandrolone
DHEA
Androstenedione
DHEA and Androstenedione:
Precursors of Testosterone
DHEA
Androstenedione
DHT
Testosterone
Estrone (E1)
Estradiol (E2)
Effects of DHEA and Androstenedione After
12 Weeks of Training
Wallace et al., MSSE, 1999
Protein Supplementation
 Research suggests that
athletes have 2-3X RDA
higher protein needs
 Typical American athletes
already consume this amount
 Increased carbohydrate
intake more important to
increasing muscle mass
Fatigue: Implications for Ergogenic
Aids
 Power/Speed events
–
–
–
–
muscle mass
CNS & sympathetic stimulation
acidosis
depletion of PCr
 Endurance events
–
–
–
–
–
muscle glycogen depletion
low blood [glucose]
fat oxidation rate
dehydration
diminished O2 delivery
Bicarbonate Loading
 Intramuscular effects of acidosis
–  PFK, phosphorylase
–  Ca2+ sensitivity
–  cross-bridge force output
–  ATP turnover
– slows recovery rate
 Effects of bicarbonate loading
–  plasma pH
– speeds H+ and La- transport from muscle
Benefits of Bicarbonate Loading
 not all studies report performance
benefits
– dependent on dosing
– benefits maximal exercise of 1-10 min
– GI distress
Performance After Bicarbonate Loading
Costill et al., Int J Sports Med, 1984
High-Intensity Exercise Effects on Muscle
Metabolites
force
lactate
PCr
ATP
Endurance Training Adaptations





 VO2max (~15%)
 cardiac output (~15%)
 mitochondrial volume (2X)
La threshold shifted to right
 ability to use fats (spares glycogen)
Increasing O2 Delivery
 blood doping
–  RBC and blood volume
–  submax pH
–  La, HR
 breathing 100% O2
 EPO
– stimulates RBC production
 altitude training
– live high, train low
ACSM Position Stand, The use of blood doping as an
ergogenic aid. MSSE, 28:i-viii, 1996.
Effect of Blood Doping on VO2max
and Fatigue
Performance
After Blood
Doping
Performance
After Inhalation
of 100% O2
What limits endurance performance?
Cytochrome
oxidase
Pyrave-malate
oxidase
Palmitoyl
carnitine oxidase
VO2max
Pyruvatemalate
oxidase
Palmitoyl
carnitine
oxidase
VO2max
Maximal
endurance
.95
.93
.74
.92
.89
.68
.89
.71
.91
.70
Davies et al., 1981, 1982
What limits endurance performance?
Recovery in rats
restored to normal ironintake diet.
Davies et al., AJP, 1982
Increasing Energy Supply
 Carbohydrate
availability
Glucose
– feeding before/during
competition
– enhancing fat use
 Creatine
– important for energy
production during
power/speed events
Increasing Fat Utilization
 FA availability will  fat oxidation
 Caffeine
–  lipolysis?
–  EPI release?
– blocks adenosine receptors
– inhibits phosphodiesterase
 Ephedrine
– ß-receptor agonist
Increasing Fat Availability
 Caffeine
–
–
–
–
–
–
–
 fat availability and  carbohydrate use?
spares carbohydrate stores?
 threshold for motor unit recruitment
altered E-C coupling
facilitated nerve transmission
 ion transport w/in muscle
 catecholamine release
 Other nutritional products
Carbohydrate
Feeding
During
Exercise
Ivy et al., MSSE, 1979
Effect of Diet on Carbohydrate
Storage and Exercise Duration
CHO intake
(g/24 h)
100 (15%)
280 (55%)
500 (98%)
Glycogen
content
(mmol/kg)
53
100
205
Exercise
time
(min)
57
114
167
Effect of Diet on Muscle
Carbohydrate Storage
Costill & Miller, IJSM, 1979
Other Banned Substances
 Stimulants – reduces tiredness
– ephedrine, cocaine,
amphetamines
 Painkillers
– narcotics
 Diuretics
– rapid weight loss
– masks steroid use
Dehydration and
Performance
Saltin & Costill, 1988
If you were to design a new
ergogenic aid for a(n),
 endurance athlete
 speed athlete
 power athlete
what physiological mechanism(s) would be
affected that result in better performances?