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Unformatted text preview: n currently active triathletes performed four
20-second all-out sprints on an air-braked cycle
ergometer with each trial separated by 20-second
recovery periods. Muscle biopsies were obtained so
that subjects could be matched for intramuscular Cr
content before they were randomly assigned to receive either a Cr (n = 8; 20 g/day for 20 days) or a
placebo group (n = 8). Results indicated that free Cr
was significantly higher in the Cr group compared
with no change in the placebo group; however, there
were no significant differences between groups regarding test performance parameters.
3. Potential Adverse Effects
It appears as though the consensus, regarding
issues of possible adverse effects from Cr supplementation, is that there is no strong scientific evidence to support any reported adverse effects. Most
of the reports have been rather minor in nature and
purely anecdotal; however, it is critical to note that
well controlled, long-term studies in humans are
Sports Med 2005; 35 (2) 122 Bemben & Lamont lacking, therefore, caution should still be used if Cr
is to be used on a long-term basis.
3.1 Gastrointestinal (Stomach Cramping,
Nausea, Diarrhoea, Vomiting) Perhaps the most often reported adverse effect of
Cr supplementation is gastrointestinal (GI) distress.
It appears that, if the Cr is insufficiently dissolved[9,18] or if it is ingested during or immediately
after exercise, there seems to be more reports of
stomach upset. However, when a placebo group has
been included and the study has been double blinded, there appears to no detrimental effect on the GI
In a recent double-blind study completed by our
laboratory that examined the effects of Cr supplementation, protein supplementation, a combination
of both Cr and protein supplements, or a placebo
supplementation in 40- to 60-year-old men, we had
essentially no reports of any GI upset (nausea,
vomiting or diarrhoea) when the drinks were consumed immediately following a resistance training
programme designed to facilitate muscle hypertrophy (three sets, ten exercises, 80% 1RM). Subjec...
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