letes are unable to make concrete choices about,
for example, how much sodium bicarbonate/
citrate should be used or over what time periods
it is effective.
Several authors (Wijnen et al.1984; McKenzie
et al.1986; Parry-Billings & MacLaren 1986) have
used a research paradigm involving multiple
exercise bouts interspersed with rest/recovery.
The exercise periods have varied, but have been
between 30 and 60 s with rest/recovery periods
from 60 s (Wijnen et al.1984; McKenzie et al.1986)
to 6 min (Parry-Billings & MacLaren 1986). The
results of this work have generally been incon-
clusive. Wijnen et al.(1984) infused bicarbonate
intravenously in one of two doses (180 or 360 mg·
kg-^1 body mass) while subjects rode a cycle
ergometer for 60 s with a rest period of 60 s, and
repeated this a further three times. Both dosages
of NaHCO 3 significantly raised pH (P<0.01)
above the control condition in a manner which
was dependent upon the dosage. However, as
has been shown in some studies previously, the
increased pH did not lead to an increase in per-
formance in all subjects. McKenzie et al.(1986)
used a protocol similar to that of Wijnen et al.
(1984), but used dosages of either 150 or 300 mg ·
kg-^1 body mass. Blood pH and blood bicarbonate
levels increased in both experimental conditions
when compared with the control treatment.
When time to fatigue and the amount of work
done were compared, the two experimental con-
ditions both increased these parameters but with
no difference between the two dose levels. In
another interval type paradigm, Parry-Billings
and MacLaren (1986) again found that a dose of
300 mg · kg-^1 body mass had no effect on 30 s of
exercise when interspersed with 6-min recovery
periods. Again, this was despite an increase in
blood bicarbonate levels of approximately
8 mmol · l-^1 above control levels.
Bicarbonate dose and exercise
Various studies have suggested, either directly or
indirectly, that there is a minimum level of
sodium bicarbonate ingestion needed to improve
performance. Katz et al.(1984) found no differ-
398 nutrition and exercise
ences in performance time on a cycle ergometer
test at 125% V.
o2max.after subjects ingested 200 mg
NaHCO 3 ·kg-^1 body mass despite significant (P<
0.001) rises in pH prior to exercise. Blood
bicarbonate and base excess also significantly
increased and the hydrogen ion to lactate ratio
(nmol/mmol) was significantly lower in the
experimental trial than in the control trial, all of
which suggest that buffering was available but
for some reason was not effective. Horswill et al.
(1988) also found no improvement in exercise
performance with dosages between 100 and
200 mg · kg-^1. In this interesting experiment, the
authors (Horswill et al.1988) had subjects under-
take four 2-min sprint tests after they had con-
sumed either a placebo or one of three doses
of sodium bicarbonate (100, 150 or 200 mg · kg-^1 ).
Pretest plasma bicarbonate levels were not dif-
ferent, nor were they different between the
placebo and 100 mg · kg-^1 groups 1 h after the
test, but they were significantly increased in
the 150 and 200 mg · kg-^1 conditions. Even
though plasma bicarbonate levels increased with
the latter dosages, subjects were still unable to
use the increased buffer capacity given by the
NaHCO 3.
In a study from our laboratory (McNaughton
1992a), we attempted to extend the work of
Horswillet al.(1988) to determine which dosage
was most efficacious. We also decided to use an
exercise bout of 60 s, since previous experience
had led us to believe this would elicit high blood
lactate levels and low levels of blood pH. Each of
the subjects undertook a total of seven tests: one
control, one placebo and one of five doses of
NaHCO 3 (100, 200, 300, 400 and 500 mg · kg-^1 )
(Fig. 29.3). These were undertaken in a random
fashion, after the control test, which was always
first. The ingestion of sodium bicarbonate as a
dose of 100 mg · kg-^1 did not increase blood bicar-
bonate levels, in agreement with the work of
Horswillet al.(1988). Larger doses had the effect
of significantly increasing the levels of blood
bicarbonate.
Unlike Horswill et al.(1988), this author found
a significant increase in performance with a dose
of 200 mg · kg-^1 and this improvement increased