hydroxy-b-methylbutyrate (HMB) from leucine;
nutraceuticals or phytochemicals, non-drug
substances found in plants that are purported to
affect metabolism, such as ginseng; non-essential
nutrients, such as creatine; and drug nutrients,
legal drugs found naturally in foods or bever-
ages consumed by humans, such as alcohol and
caffeine. Examples of these nutritional ergogenic
aids can be categorized as follows.
1 Megadoses of essential nutrients:
(a) amino acids: arginine, ornithine, lysine and
tryptophan;
(b) vitamins: vitamin B12,vitamin C and
vitamin E;
(c) minerals: boron, chromium and
phosphates.
2 Engineered metabolic by-products of essential
nutrients:
(a) HMB (b-hydroxy-b-methylbutyrate);
(b) DHAP (dihydroxyacetone plus pyruvate);
(c) FDP (fructose diphosphate).
3 Non-essential nutrients:
(a) carnitine;
(b) choline;
(c) glycerol;
(d) inosine.
4 Plant extracts (phytochemicals):
(a) gamma oryzanol;
(b) ginseng;
(c) wheat germ oil;
(d) yohimbine.
5 Drug nutrients:
(a) alcohol;
(b) caffeine.
Nutritional ergogenic aids may be used in
attempts to increase sport performance in
various ways, such as: increased energy supply
in the muscle (e.g. creatine supplements);
increased energy-releasing metabolic processes
in the muscle (e.g. l-carnitine supplements);
enhanced oxygen delivery to the muscle (e.g.
iron supplements); increased oxygen utilization
in the muscle (e.g. coenzyme Q 10 supplements);
decreased production or accumulation of
fatigue-causing metabolites in the muscle
(e.g. sodium bicarbonate supplements); and
improved neural control of muscle contraction
(e.g. choline supplements). Because all nutrients
may be involved in energy production or control
in one way or another, every nutrient may be
potentially ergogenic for specific sport tasks. The
potential capacity of many specific essential
and non-essential nutrients to enhance the three
human energy systems is detailed in other chap-
ters of this volume, including the role of creatine
supplementation to enhance the ATP–PCr
energy system, the ingestion of sodium bicarbon-
ate to improve performance in sport events asso-
ciated with the lactic acid energy system, and
dietary carbohydrate regimens to increase
aerobic endurance capacity associated with the
oxygen energy system.
This brief review will focus on several nutri-
tional ergogenics commonly marketed to ath-
letes as dietary supplements with alleged
ergogenic properties to improve performance in
(i) strength/power sport tasks, and (ii) aerobic
endurance sport tasks.Strength/power sport tasks
Arginine, ornithine and lysinetheory
Human growth hormone (hGH), a polypeptide,
is released from the pituitary gland into the
bloodstream and affects all body tissues. Supple-
mentation with various amino acids, particularly
arginine, ornithine and lysine, has been used
in attempts to stimulate the release of hGH.
Increased serum levels of hGH in turn may
stimulate production and release of insulin-like
growth factor-1 that may lead to increases in
muscle mass and strength. Additionally, amino
acid supplementation is theorized to stimulate
the release of insulin, another anabolic hormone.efficacy
In early research, Elam (1989) reported that in
conjunction with a weight-training programme,
supplementation with arginine (1 g · day–1) and
ornithine (1 g · day–1) reduced body fat, increased