topic 11

Ergogenic – to increase work, especially to increase potential for work output

Nutritional Agents:

🍞 Carbohydrates – endurance performance (time to exhaustion) linked to glycogen content of muscle.

• Athletes use "glycogen loading" to improve endurance performance since glycogen depletion is a major cause of fatigue/exhaustion.

• By eating complex CHO rich diet for 3 days, glycogen content of muscle is almost doubled, and time to exhaustion improved.

• Must also maintain blood glucose levels during prolonged (1–4 hours) exercise. Intensity can’t be maintained when blood glucose is low.

• CHO consumption (with fluids) improves endurance performance, but only in late phase (>90 min) of extended bout.

• Consuming CHOs during prolonged exercise does not directly spare muscle glycogen, but preserves liver glycogen. Enables working muscles to rely more on blood glucose in sessions lasting more than 90 min.

• Do not ingest CHOs shortly (<45 min) before start of exercise, as this causes hypoglycemia (insulin response), resulting in early fatigue since muscle deprived of circulating energy source. During exercise, CHO consumption doesn’t stimulate insulin release.

🥑 Fats – (low intensity, not high intensity) exercise. Rich source of energy both at rest & during exercise.

• Unlike CHOs, simply eating more fats will not increase use of fats during exercise.

• Muscle can only use FFAs. Eating more fat raises triglycerides, not FFAs.

• Some stimulants (e.g., caffeine) do increase circulating FFAs & improve prolonged exercise of moderate intensity. However, effects are inconsistent. (complete protein w/ full amino acid profile)

Protein – small role as substrate, but this can increase if diet rich with proteins.

• Many have used protein supplements for muscle growth & repair.

• RDA for protein is 0.8 g/kg body weight.

• Protein needs greater for athletes in training.

• Strength training requires protein intake of 1.4–1.8 g/kg body weight (don’t overconsume or else kidneys damaged)

• Endurance training requires protein uptake of 1.2–1.4 g/kg body weight.

• In strength trained athletes, consuming more than 1.8 g/kg no more effective in building muscle mass.

• Uptake of more than 2.0 g/kg may present health risks (renal system taxed in trying to eliminate excess nitrogenous waste).

Pharmacological Agents:

1) Amphetamines – CNS stimulants. First used to enhance endurance performance by troops during WWII to prevent or delay fatigue.

Physiological effects:

• ↑ BP

• ↑ HR

• Shunting of blood to skeletal muscles

• ↑ blood glucose & FFAs

• ↑ muscle tension

Fight/Flight Response – Always Under Drug

Performance effects:

• ↑ speed

• ↑ power

• ↑ endurance ( ↑ time to exhaustion, but no change in VO₂ max)

• ↑ strength

• ↑ fine motor coordination

Risks:

• Addictive

• Tremor

• Cardiac arrhythmias

• Delay "sensation" of fatigue, push CV system too far

• Anorexia

• Vomiting

• Insomnia

• Cerebral hemorrhage

• irritability

2) Caffeine – CNS stimulant, found naturally in coffee, tea, chocolate, soft drinks.

Physiological effects: Same as amphetamines, but weaker

• ↓ fatigue, delays its onset

• ↓ reaction time (quicker reactions)

• ↑ catecholamine release (stimulates HSL) → breakdown of tg into FFAs

• ↑ circulating FFAs

• ↑ use of intramuscular triglycerides

Performance effects:

• ↑ endurance performance, extends time to exhaustion

• May improve strength & sprint times (↑ release of Ca²⁺ from SR; helps Na⁺/K⁺ pump maintain sarcolemmal excitability)

Risks:

• Addiction

• Insomnia

• Tremor

• Diuresis → ↑ susceptibility to dehydration/heat injury

Hormonal Agents:

1) Anabolic Steroids

• Came into use in athletes in early 1950s. Stimulate natural hormone testosterone.

• Synthetic steroids try to separate androgenic (male sexual) from anabolic (muscle building) properties.

Proposed effects:

• ↑ muscle mass (strength), facilitate recovery from intense workouts, improve aerobic capacity (VO₂ max)

Proven effects:

• Very few well-controlled studies, those available show:

  • ↑ body mass

  • ↑ fat-free mass

  • ↑ muscle size

  • ↑ strength

With low doses of steroids, evidence shows:

• 1–2 kg increase in fat-free mass (more with high doses)

• More effective when combined with heavy resistance training

• No significant effect on VO₂ max, but high doses do ↑ RBC production

• No evidence that recovery is facilitated

Risks:

• Banned by sports/athletic associations

• In young athletes, can prevent normal bone growth (ossify epiphyseal bands)

• In males, ↓ secretion of testosterone, testicular atrophy, ↓ sperm count

• In males, can cause prostate enlargement, ↑ risk of prostate cancer

• In females, interferes with natural hormone regulating ovulation, can develop masculine secondary sexual characteristics

• In males & females, liver & heart damage, ↓ HDL’s