Smith M S, Dyson R, Hale T, Harrison J H, McManus P
Centre for Sports Science and Medicine, University College Chichester, UK.
Eur J Appl Physiol. 2000 Sep;83(1):34-9. doi: 10.1007/s004210000251.
The physiological effects of strategies for a rapid loss of body mass immediately before weighing-in for competition in weight-governed sports are unclear. This study examined the effects of a 3%-4% loss in body mass on a boxing-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 subjects 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 changes in plasma volume (PV) were inconsistent. Four subjects suffered reductions in PV between 15% and 30%, one subject maintained his E-trial value and two recorded an increase. The D-trial mean PV value was 8.0 (SD +/- 17.2)% lower but this fall was not statistically significant (P>0.05). Analysis of 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 (F1,6 = 3.93 P>0.05), time (F1.83,48 = 1.12, P>0.05) or interaction between them (F1.93,48, P>0.05). Furthermore, neither heart rate nor blood lactate responses in the boxing task differed between trials. These data were affected by the small sample. Power and effect size analysis using eta(2) procedure and removing the outlier data produced a mean fall in boxing performance of 26.8%. However, some subjects 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 mechanisms under-pinning this ability.
在体重控制类运动项目称重前迅速减轻体重的策略所产生的生理影响尚不清楚。本研究考察了体重减轻3%-4%对一项拳击相关任务的影响。七名新手业余拳击手在处于水合状态时（E组试验）以及运动诱导的热脱水后（D组试验），在一台原型拳击测力计上完成了三轮3分钟的模拟拳击。脱水后所有受试者体重均下降——平均体重下降了3.8（标准差±0.3）%[从77.3（标准差±11.3）千克降至74.4（标准差±10.7）千克，P<0.001]——但血浆容量（PV）的变化并不一致。四名受试者的PV减少了15%至30%，一名受试者维持了其E组试验时的值，两名受试者的PV有所增加。D组试验的平均PV值低了8.0（标准差±17.2）%，但这种下降无统计学意义（P>0.05）。对D组试验拳击表现的分析表明，一名受试者在两次试验中保持了其表现，另一名受试者提高了17.8%。一项对两个因素都进行重复测量的双向方差分析（条件×时间）显示，条件（F1,6 = 3.93，P>0.05）、时间（F1.83,48 = 1.12，P>0.05）或它们之间的交互作用（F1.93,48，P>0.05）均无显著的主效应差异。此外，拳击任务中的心率和血乳酸反应在两次试验之间也没有差异。这些数据受到样本量小的影响。使用η²程序并去除异常值数据进行的功效和效应量分析得出拳击表现平均下降了26.8%。然而，一些受试者似乎能够抵抗比赛前迅速减轻体重的有害影响，需要进一步研究来解释支撑这种能力的机制。
