The effect in humans of rapid loss of body mass on a boxing-related task

The physiological effects of strategies for a rapid loss of body mass immed iately before weighing in for competition in weight-governed sports are unc lear. This study examined the effects of a 3%-4% loss in body mass on a box ing-related task. Seven novice amateur boxers completed three 3 min rounds of simulated boxing on a prototype boxing ergometer in an euhydrated state (E-trial) and after exercise-induced thermal dehydration (D-trial). All sub jects lost body mass following dehydration-mean body mass fell 3.8 (SD +/- 0.3)% [77.3 (SD +/- 11.3) to 74.4 (SD +/- 10.7) kg. P < 0.001] - but change s in plasma volume (PV) were inconsistent. Four subjects suffered reduction s in PV between 15% and 30%: one subject maintained his E-trial value and t wo recorded an increase. The D-trial mean PV value was 8.0 (SD +/- 17.2)% l ower bur this fall was not statistically significant (P > 0.05). Analysis o f D-trial boxing performance showed one subject maintained his performance over the two trials and a second improved 17.8%. A two-way ANOVA (condition x time) with repeated measures on both factors showed no significant main effect differences for condition (F-1.6 = 3.93 P > 0.05), time (F-1 83.48 = 1.12, P > 0.05) or interaction between them (F-1 93.48, P > 0.05). Further more, neither heart rate nor blood lactate responses in the boxing task dif fered between trials. These data were affected by the small sample. Power a nd effect size analysis using eta(2) procedure and removing the outlier dat a produced a mean fall in boxing performance of 26.8%. However. some subjec ts appeared able to resist the deleterious effects of a rapid loss of body mass prior to competition and further research is needed to explain the mec hanisms under-pinning this ability.