This study examined the effects of serial reductions in energy and fluid in
take on two simulated boxing performances separated by 2 days recovery. Eig
ht amateur boxers (age: 23.6 +/- 3.2 years; height 275 +/- 5 cm; body mass
[BM] 73.3 +/- 8.3 kg [Mean +/- SD]) performed two simulated boxing bouts (B
B) under normal (N-trial) and restricted (R-trial) diets in a counterbalanc
ed design over 5 days. The trials were separated by a 9-day period of norma
l dietary behavior (X-trial). BM was recorded on days 1, 3, and 5 of each t
rial. Simulated bouts of three, 3-min rounds with I-min recovery were compl
eted on days 3 (BB 1) and 5 (BB2) of each 5-day trial. Punching force (N) w
as recorded from 8 sets of 7 punches by a purpose-built boxing ergometer. H
eart rate (f(C)) was monitored continuously (PE3000 Polar Sports Tester, Ke
mpele, Finland), and blood lactate (BLa) and glucose (BG) were determined 4
-min post-performance (2300 StaPlus, YSI, Ohio). Energy and fluid intakes w
ere significantly lower in the R-trial (p < .05). Body mass was maintained
during the N-trial but fell 396 (p < .05) during the R-trial. There were no
significant differences in end-of-bout f(C) or post-bout BG, but BLa was h
igher in the N- than the R-trial (p < .05). R-trial punching forces were 3.
2% and 4.6% lower, respectively, compared to the corresponding N-trial bout
s, but the differences did not reach statistical significance. These result
s suggest that energy and fluid restrictions in weight-governed sports do n
ot always lead to a significant decrease in performance, but because of the
small sample size and big variations in individual performances, these fin
dings should be interpreted with care.