growth-enhancing properties. Additional sub-
stances are reviewed in Chapter 26. Again, there
is an absence of scientific research confirming
such effects (Rosenbloomet al.1992; Grunewald
& Bailey 1993; Coleman & Nelson-Steen 1996).
Putative enhancers of energy metabolism
In theory, performance should be enhanced if
a product ingredient increased the ability of
muscle to resynthesize adenosine triphosphate.
The most obvious candidates for such a role
would be metabolic intermediates such as
lactate, pyruvate, citrate and other tricarboxylic
acid intermediates, enzyme-system components
such as lipoic acid, alternative fuel sources such
as medium-chain triglycerides, mediators in fuel
oxidation such as carnitine, and components of
the high-energy phosphate pool such as inosine
and creatine. Of these, creatine ingestion appears
to have the most promise as an ergogenic aid
(Greenhaff 1995). As indicated in Chapter 27, cre-
atine ingestion is associated with an increase
in muscle creatine content, a response that may
be associated with increased performance in
very high intensity, short-duration activities.
However, as promising as creatine appears to be
as an ergogenic aid, and notwithstanding the
numerous products containing creatine as an
ingredient, it may still be premature to draw a
definitive conclusion regarding its efficacy.
While some laboratories have reported im-
proved sprint performance associated with crea-
tine feeding (e.g. Casey et al. 1996), others have
failed to find an effect (e.g. Barnettet al.1996).
Although the disparate results may merely be an
artefact of differences in experimental design,
feeding protocols, subject selection, and choice of
performance critieria, more research is needed to
confirm if this is indeed the case.
Conclusion
Efficacious sports nutrition products will
continue to play an important role in helping
athletes achieve and maintain a nutritional
status that positively influences body structure
530 practical issues
and function. The benefits of remaining well
hydrated during exercise, the advantages of
ingesting a diet high in carbohydrate content,
the importance of sodium in stimulating rapid
and complete rehydration, and the indispensible
nature of consuming adequate energy are exam-
ples of well-documented nutritional applications
around which many sports nutrition products
are based. There are, however, many products
that are associated with claims that lack scien-
tific substantiation. Sports health professionals
involved in public-education programmes have
an obligation to help provide consumers with
up-to-date and accurate information regarding
the veracity of product claims.References
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