nor was there any effect on performance in a 4.8-
km treadmill run for time (Williams et al. 1990).
Five days of inosine supplementation (5000 mg ·
day–1) did not influence peak power, end power,
a fatigue index, total work, or post-test lactate in
competitive male cyclists undertaking several
cycle ergometer exercise tasks (Starling et al.
1996). In both studies, inosine supplementation
actually impaired performance in some of the
tests, including run time to exhaustion in a peak
oxygen uptake test (Williams et al. 1990) and
time to fatigue in a supramaximal cycling sprint
(Starlinget al. 1996).
safety
Inosine supplementation appears to be relatively
safe, but may increase production of uric acid
which could lead to complications in those
afflicted with gout.
Glycerol
theory
Glycerol is an alcohol derived from triglycerides.
Investigators theorize that a combination of
glycerol–water supplementation may be a more
effective hyperhydration technique than water
hyperhydration alone. Increasing body water
stores may be theorized to enhance aerobic
endurance performance, either by increasing
blood volume or by increasing resistance to
dehydration while exercising under heat-stress
environmental conditions.
efficacy
Glycerol-induced hyperhydration (ª1 g glycerol ·
kg–1body weight with 20–25 ml water · g–1glyc-
erol), when compared with water hyperhy-
dration alone, has been shown to increase total
body water, including blood volume, to a greater
extent (DeLuca et al. 1993; Freund et al. 1993;
Sawkaet al. 1993). Several studies have shown
that glycerol-induced hyperhydration improves
cardiovascular responses, temperature regula-
tion, and cycling exercise performance under
warm/hot environmental conditions (Lyons
et al. 1990; Montner et al. 1992). However, Lamb
and others (1997) reported that glycerol-induced
hyperhydration exerted no significant effect on
temperature regulation, physiological or meta-
bolic responses to exercise, or prolonged cycling
performance. Additional research is needed to
help resolve these contradictory findings,
particularly so in sports in which the extra body
mass needs to be moved, such as distance
running.safety
Although the dosages used in these studies
appear to be safe, larger doses may lead to abnor-
mal pressures in tissue spaces.Ginsengtheory
Ginseng, a plant extract, is a generic term encom-
passing a wide variety of compounds derived
from the family Araliaceae. The ergogenic effect
of ginseng is attributed to specific glycosides,
also referred to as ginseng saponins or gin-
senosides. The specific physiological effects of
ginseng extracts depend on the plant species, the
various forms including Chinese or Korean
ginseng (Panax ginseng), American ginseng (P.
quinquefolium), Japanese ginseng (P. japonicum)
and Russian/Siberian ginseng (Eleutherococcus
senticosus). Although the mechanism underlying
the alleged ergogenicity of ginseng on physical
performance has not been defined, theories
include stimulation of the hypothalamic–
pituitary–adrenal cortex axis and increased
resistance to the stress of exercise, enhanced
myocardial metabolism, increased haemoglobin
levels, vasodilation, increased oxygen extraction
by muscles, and improved mitochondrial metab-
olism in the muscle, all of which theoretically
could enhance aerobic exercise performance
(Dowlinget al. 1996).