researched of all sports nutrition products. For-
mulated to rapidly replace fluid lost as sweat
during physical activity, sports drinks com-
monly contain a mixture of mono-, di- and
oligosaccharides (as maltodextrins), minerals
(most often sodium, potassium and chloride),
along with assorted flavourings. The carbohy-
drate concentration of most commercially avail-
able sports drinks ranges from 5% to 8%
carbohydrate (i.e. 50–80 g carbohydrate per litre).
The physiological effectiveness of sports drink
ingestion has been well documented (Lamb &
Brodowicz 1986; Murray 1987; Maughan 1991;
Maughanet al. 1995) and the plethora of related
data provided part of the foundation for the posi-
tion stand on exercise and fluid replacement
published by the American College of Sports
Medicine (ACSM 1996). Chapters 15–19 of
this text provide an excellent review of issues
regarding fluid and electrolyte homeostasis and
Chapter 8 addresses the topic of carbohydrate
feeding during exercise.
Carbohydrate-rich beverages
The value of ingesting a diet high in carbohy-
drate content has been well established, as
detailed in Chapters 5–8. Any food or beverage
high in carbohydrate content could conceivably
be termed a carbohydrate-loading supplement,
although this designation is usually applied to
commercial products, most often beverages.
Whether purchased in liquid form or recon-
stituted from a powder mix, these beverages
should contain a carbohydrate concentration in
excess of regular soft drinks (10–14% carbohy-
drate) and common fruit juices (12–16% carbohy-
drate). It is accepted at face validity that the
ingestion of adequate amounts of such products
will help athletes meet their goals for dietary
carbohydrate intake, the result of which will be
effective restoration of glycogen stores in liver
and muscle.
Complete-nutrition/energy beverages
These beverages, usually in the form of milk-
528 practical issues
shake type drinks, contain varying combinations
of carbohydrate, protein, fat, vitamins and min-
erals. Some of these products contain an array of
other nutrients and metabolites. It is accepted at
face validity that the ingestion of these supple-
ments will provide the energy and nutrients
included in them, the inference being that intake
of the nutrients will help athletes meet their daily
nutritional needs. Additional claims of product
benefits to structure or function (e.g. ‘adds lean
body mass’, ‘boosts fat metabolism by 43%’)
would require direct substantiation by accept-
able scientific research.Energy bars
This category of supplements includes solid
foods in bar form. Most bars provide 140–250
kcal (588–1050 kJ) of energy and contain varying
proportions of carbohydrate, protein, fat and
micronutrients. Most of these products are asso-
ciated with statements of nutritional content (e.g.
‘contains ginseng’), although a few make struc-
ture or function claims (e.g. ‘burn more body
fat’). In the latter case, the manufacturers must
be held accountable for providing acceptable
scientific support.Carbohydrate gels
These products are often small packets of
carbohydrate syrup (20–30 g) positioned for use
during prolonged exercise as an alternative
means of carbohydrate intake. The claims made
for these products are most often statements of
nutritional content. Most products advise the
user to ingest the gel with ample amounts of
fluid to help assure rapid gastric emptying.Vitamin supplements
Vitamins are sold as single nutrients (e.g. vitamin
C),in combination with other vitamins (e.g. B
complex vitamins), or as vitamin–mineral tablets
that contain assorted nutrients. Some manufac-
turers employ a use-specific positioning for their
products that imply particular benefits (e.g. ‘an