NUTRITION IN SPORT

(Martin Jones) #1

each of the eight subjects. The work output
increased significantly (P<0.01) in the experi-
mental condition when compared with the
control or placebo condition (9940, 9263 and 9288
J, respectively). In the NaHCO 3 trial, pretest
blood bicarbonate levels increased significantly
above either the resting or control/placebo
pretest levels. An interesting finding in this study
was that the peak power, as measured in watts,
achieved by the subjects, also increased signifi-
cantly (P<0.05) in the experimental condition
when compared with that in the control or
placebo conditions.
In order to examine more closely the time
periods over which sodium bicarbonate can be
used as an ergogenic aid, McNaughton (1992b)
studied four different time periods (10, 30, 120
and 240 s) with a dosage of 300 mg · kg-^1 body
mass. Subjects ingested sodium bicarbonate or a
placebo and undertook a control test. There were
eight male subjects in each time group, and each
subject undertook three test sessions. As is usual
with a dosage of this size (300 mg · kg-^1 ), the
blood bicarbonate levels were increased in the
experimental trial when compared with those in
either the control or placebo trials. This was also
true for the base excess and pH measurements.
However, the work and power data collected
during the cycle ergometer tests over the four
time periods were only significantly different in
the latter two time periods (120 and 240 s), even
though the blood lactate levels in both the 10-
and 30-s trial were significantly higher after exer-
cise than the pre-exercise levels.
This work is in agreement with several other
studies suggesting that NaHCO 3 loading is
not effective for short-term anaerobic work
(McCartneyet al.1983; Katz et al.1984) but that it
is effective for longer-term work (Wilkes et al.
1983; McKenzie et al.1986; Goldfinch et al.1988).
McNaughton and Cedaro (1991) found the same
dosage of sodium bicarbonate to be effective in
rowing performance of 6 min duration using elite
rowers.


400 nutrition and exercise


Sodium citrate
A number of authors (Simmons & Hardt 1973;
Parry-Billings & MacLaren 1986; McNaughton
1990; McNaughton & Cedaro 1991b) have used
sodium citrate as an alkalizing agent rather than
sodium bicarbonate. The results of work from
our laboratory (McNaughton 1990) would
suggest that sodium citrate is an effective
ergogenic substance when given in dosages
between 300 and 500 mg · kg-^1 body mass, with
anaerobic capacity increasing in a linear fashion
in relation to these doses (McNaughton 1990). In
relation to duration of exercise, the high dosage
of sodium citrate appears to be effective in time
periods of between 2 and 4 min (McNaughton &
Cedaro 1991b). Sodium citrate does not appear to
be an effective ergogen when used with short-
term (30 s) maximal exercise (Parry-Billings &
MacLaren 1986; McNaughton & Cedaro 1991b).
A recent article (Potteiger et al.1996) has also sug-
gested that large doses (500 mg · kg-^1 body mass)
of sodium citrate may improve 30-km cycling
performance. These competitive cyclists com-
pleted the placebo 30-km trial in 3562.3 ±108.5 s,
while in the citrate trial they completed the same
distance in 3459.6 ±97.4 s. More work needs to be
undertaken to determine if this regimen can be
applied to other endurance activities.
Some subjects have reported short-term gas-
trointestinal distress as a side-effect of sodium
bicarbonate/citrate use (Wilkes et al. 1983;
Goldfinchet al.1988; McNaughton & Cedaro
1991b). Other possible side-effects have been
noted including gastric rupture (Downs &
Stonebridge 1989; Reynolds 1989), muscle
spasms and cardiac arrhythmias (Reynolds 1989;
Heigenhauser & Jones 1991).
Although detection of sodium bicarbonate and
citrate is difficult, several authors (Wilkes et al.
1983; Gledhill 1984; McKenzie 1988) have sug-
gested it is possible to detect, and therefore
control, using existing procedures (urine sample,
post-exercise). The work of McKenzie (1988) is
most detailed, with subjects providing a post-
exercise urine sample. Of the 65 subjects, no sub-
jects who had ingested NaHCO 3 had a urinary
Free download pdf