effects of two volumes (1.5 L or 3.0 L) of commercially available
electrolyte beverage (1.44 mM·L-1 Na+) taken
during a 24-hour recovery period post-exercise, on plasma volume (PV)
expansion 24-hours post-exercise were assessed. A simple random-order
crossover research design was used. Subjects (n = 9 males: age 21
± 4 years, body mass 80.0 ± 9.0 kg, peak incremental 60-second cycling
power output 297 ± 45 W [means ± SD]) completed an identical exercise
protocol conducted in hot ambient conditions (35oC, 50%
relative humidity) on two occasions; separated by 7-days. On each
occasion, subjects received a different volume of 24-hour fluid intake
(commercial beverage) in random order. In each case, the fluid was
taken in five equal aliquots over 24-hours. PV expansions 24-hours
post-exercise were estimated from changes in haemoglobin and haematocrit.
Dependent t-testing revealed no significant differences in PV expansions
between trials, however a significant expansion with respect to zero
was identified in the 3.0 L trial only. Specifically, PV expansions
(%) were; 1.5 L trial: (mean ± SE) 2.3 ± 2.0 (not significant with
respect to zero), 3.0 L trial: 5.0 ± 2.0 (p < 0.05, with respect
to zero). Under the conditions imposed in the current study, ingesting
the greater volume of the beverage lead to larger mean PV expansion.
WORDS: Hypervolemia, dehydration, re-hydration.