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Unformatted text preview: or to performance of
the AST, four 15-second bursts of high-intensity
running, each separated by 30 seconds of passive
recovery, were performed to ensure depletion of PCr
stores. Statistical analysis revealed that there were
no significant group or interaction effects for performance times on the treadmill or blood lactate
concentrations. There was a significant interaction
for plasma ammonia concentrations indicating a
trend for plasma ammonia to decrease for the Cr
group. These data suggest that, during the present
study, Cr supplementation offered no ergogenic advantage over the placebo condition with regard to
No improvements in performance were also
demonstrated by Preen et al., who studied the 2005 Adis Data Information BV. All rights reserved. 121 effect of pre-exercise Cr supplementation on intermittent sprint performance. Eight active, but not
well trained men either received Cr (15g + water) or
a placebo treatment during their first day of testing.
Fourteen days later, in a randomised, double-blind,
crossover design, subjects were then re-tested before
ingesting the other treatment that was not received
on the first test. Cr or placebo treatments were
ingested 60 and 120 minutes prior to the start of an
80-minute sprint cycle task. The protocol consisted
of ten sets of multiple 6-second sprints, with recovery periods varying from 24 to 84 seconds. Subjects
carried out the same protocol 14 days later and
received the alternative treatment to what was received previously. Variables recorded and analysed
included work done and peak power. Muscle biopsies were also taken from the vastus lateralis prior to
exercise and at 1 and 3 minutes post-exercise. Data
analyses revealed that there were no significant
changes in cycling performance after ingestion of Cr
and that muscle ATP concentrations and total Cr
levels were not different between the two groups.
Finn et al. also reported no difference in intermittent cycle performance following Cr ingestion.
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