Introduction
The optimal production, control and efficiency of
human energy is the key composite determinant
of all muscular power for movement in sport. In
general, as noted in previous chapters, sport sci-
entists recognize three major human muscle
energy systems important for the generation of
adenosine triphosphate (ATP) for muscle con-
traction and subsequent power production.
The ATP–phosphocreatine (ATP–PCr) energy
system, which uses adenosine triphosphate and
creatine phosphate as its fuel sources, generates
maximal anaerobic power for very short periods
of time, such as 10 s for a 100-m dash. The lactic
acid energy system, which utilizes carbohydrate
via anaerobic glycolysis, is capable of sustaining
high anaerobic power production, such as 45 s
for a 400-m run. The oxidative energy system,
which uses carbohydrates via aerobic glycolysis
and fats via b-oxidation, can sustain aerobic
power for prolonged endurance events, such as
130 min for a 42.2-km marathon.
The three human muscle energy systems
depend on various dietary nutrients for optimal
functioning. Dietary carbohydrates and fats, two
of the macronutrients, provide the main sources
of energy. Protein, another macronutrient, may
also serve as an energy source, but as the amino
acids released by protein degradation are either
reutilized or oxidized, the amount of protein oxi-
dized per day must be replenished by dietary
intake. Protein is utilized primarily to synthesize
muscle tissue that serves as the structural
basis for energy production, and to synthesize
enzymes, hormones, and other physiological
substances that, along with vitamins and miner-
als (micronutrients), help regulate the myriad
of neural, hormonal and metabolic processes
involved in the release of energy from carbohy-
drates and fats for use during sport-related exer-
cise tasks.
Most sport nutritionists recommend that ath-
letes consume a balanced diet of macronutrients
and micronutrients to provide adequate energy,
regulate metabolic processes properly, and main-
tain an optimal body mass specific to their sport.
In general, dietary guidelines for healthy eating
developed for the average population are also
applicable to athletes. However, considerable
research effort has been expended to determine
whether or not dietary manipulation may be able
to enhance sport performance, and much of
this research has focused on the identification
and development of specific nutritional
ergogenic aids.
Nutritional ergogenic aids are purported to
enhance sport performance beyond that associ-
ated with the typical balanced diet. The major
categories targeted to physically active individu-
als include: megadoses of essential nutrients,
such as 1000 mg of vitamin C; engineered meta-
bolic byproducts of essential nutrients, such as b-Chapter 26
Nutritional Ergogenic Aids*
MELVIN H. WILLIAMS AND BRIAN C. LEUTHOLTZ
356
- Small segments of this chapter have been extracted
from Melvin H. Williams, The Ergogenics Edge: Pushing
the Limits of Sports Performance, Human Kinetics Pub-
lishers, Champaign, IL, 1998.