© 2007 McGraw-Hill Higher Education. All Rights Reserved. Presentation revised and updated by Brian B. Parr, Ph.D. University of South Carolina Aiken Chapter 25 Ergogenic Aids EXERCISE PHYSIOLOGY Theory and Application to Fitness and Performance, 6th edition Scott K. Powers & Edward T. Howley

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Objectives 1.Define ergogenic aid. 2.Explain why a “placebo” treatment in a “double-blind design” is used in research studies involving ergogenic aids. 3.Describe, in general, the effectiveness of nutritional supplements on performance. 4.Describe the effect of additional oxygen on performance; distinguish between hyperbaric oxygenation and that accomplished by breathing oxygen-enriched gas mixtures. 5.Describe blood doping and its potential for improving endurance performance.

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Objectives 6.Explain the mechanism by which ingested buffers might improve anaerobic performances. 7.Explain how amphetamines might improve exercise performance. 8.Describe the various mechanisms by which caffeine might improve performance. 9.Identify the risks associated with using chewing tobacco to obtain a nicotine “high.” 10.Describe the risks of cocaine use and how it can cause death. 11.Describe the physiological and psychological effects of different types of warm-ups.

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Ergogenic Aid  Substances or phenomena that are work-producing and are believed to increase performance –Nutrients –Drugs –Warm-up exercises –Hypnosis –Stress management –Blood doping –Oxygen breathing –Music –Extrinsic biomechanical aids

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Research Design Concerns  Amount of substance –Too little or too much may show no effect  Subject –May be effective in “untrained” but not “trained” subjects, and vice versa –The “value” as determined by the subject  Task –Endurance vs. short-term events –Large-motor vs. fine-motor activities  Use –May enhance short-term performance but compromise long-term performance

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Research Design Concerns  Placebo –Look-alike substance containing nothing that will improve performance –Athlete’s belief in a substance may influence performance  Double-blind studies –Neither the investigators nor the subjects are aware of who is receiving the treatment

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Changes in Performance–the Placebo Effect Figure 25.1

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Dietary Supplements  Little evidence that dietary supplements improve performance with the exception of creatine  Creatine monohydrate supplementation –Increase muscle phosphocreatine (PC) For short-term, explosive exercise –Supplementation increases muscle creatine levels 20–25 g/day loading dose, 2–5 d/day maintenance dose –Improves ability to maintain force and power output –Increase in muscle mass Due more to water retention than protein synthesis –Side effects Some reported, but no long-term adverse effects

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Aerobic Performance  Oxygen breathing –Increases PO 2 of blood Hyperbaric chamber -Breathing air under higher pressure Increased %O 2 mixtures -Breathing >21% O 2 mixtures at atmospheric pressure –Before or after exercise No effect on performance –During exercise No real change in O 2 delivery Improved performance -3–5% increase in VO 2max -Especially in athletes who experience desaturation Not practical

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Effect of PO 2 on Performance: O 2 Enriched Gas vs. Hyperbaric Chamber Figure 25.2

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Aerobic Performance  Blood doping –Infusion of RBCs to increase hemoglobin concentration and oxygen carrying capacity of blood Autologous vs. homologous transfusion –Effective in improving VO 2max and endurance performance –Erythropoietin (EPO) Hormone that stimulates RBC production Part of therapy for chemotherapy or dialysis patients More difficult to detect than traditional blood doping –Artificial oxygen carriers

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Changes in Hemoglobin Levels Following Removal and Reinfusion Figure 25.3

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Anaerobic Performance  Blood buffers (sodium bicarbonate) –Enhances ability to buffer H + during exercise –Improves performances of 1-10 minutes duration or repeated bouts of high-intensity exercise No benefit for tasks of less than one minute –Optimal dose 0.3 gkg body weight -1 (with 1 liter of water) –Side effects Diarrhea and vomiting

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Drugs  Amphetamines –Catecholamine-like effect –Cause increased arousal and perception of increased energy and self-confidence –Improve performance in fatigued subjects only No improvement in alert, non-fatigued subjects

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Drugs  Caffeine –May improve performance at the muscle, nervous system, or the delivery of fuel to muscle –Can elevate blood glucose and increase fat utilization –Can decrease perception of fatigue and lower RPE during prolonged exercise –Effect is variable and dose-related Effect may be diminished in regular users –Potential side effects Insomnia, diarrhea, anxiety, irritability Diuretic effect? –Caffeine-ephedrine mixtures

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Factors Influenced by Caffeine That Might Improve Performance Figure 25.4

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Mechanisms by Which Caffeine May Increase FFA Mobilization Figure 25.5

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Drugs  Cocaine –Powerful stimulator of cardiovascular and central nervous systems –May cause sudden death  Nicotine –Smoking or chewing tobacco –Can stimulate both sympathetic and parasympathetic nervous systems Cardiovascular or GI effects –Known to cause diseases of the mouth, including oral cancer

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Mechanisms by Which Cocaine Can Kill Figure 25.6

© 2007 McGraw-Hill Higher Education. All Rights Reserved. The Relaxing and Stimulating Effects of Nicotine Figure 25.7

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Physical Warm-Up  Causes both physiological and psychological changes that are beneficial to performance –Increased muscle temperature, arousal, focus on event  Warm-up activities –Identical to performance –Directly related to performance –General warm-up

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Physical Warm-Up  Recommendations –Short-term performances (≤10 s max effort) ~40–60% VO 2max for 5–10 min, followed by 5 min recovery May reduce high-energy phosphates –Intermediate-term performances (>10 s, ≤5 min) ~60–70% VO 2max for 5–10 min, followed by ≤5 min recovery Goal to begin performance with slightly elevated VO 2 –Long-term performances (≥5 min) ~60–70% VO 2max for 5–10 min Too much may deplete muscle glycogen or increase thermal strain

© 2007 McGraw-Hill Higher Education. All Rights Reserved. Stretching  Increases joint flexibility  Increases muscle-tendon compliance  Reduces risk of injury –Little support in the literature –Stretching outside periods of exercise may reduce risk of injury –Stretching just prior to exercise does not