Rapid changes of body weight after a headstand: a metrological analysis

Despite recent rules from amateur wrestling sport-governing bodies intended to discourage extreme weight loss measures, wrestling culture still includes varied methods to make weight, including holding a headstand position immediately before stepping on the scale. The procedure, according to the notion, will reduce reported mass anywhere between 250 and 500 g (weight between 2.45 and 4.89 N). The aim of this study was to compare any possible differences between the headstand procedure (HS) and a normal (CON) weight measure, using a metrological approach defined by the European Association of National Metrology Institutes. Seventeen adult men were weighed on a force plate before and after doing a headstand or standing normally for 30s. The order of treatment application was assigned randomly. Post-test weight was significantly larger than pre-test (mean ± s.d.) (640.7 ± 62.8 N and 640.3 ± 62.7 N, respectively, p < 0.0001) under both treatments. No treatment vs. time of test interaction was found. No significant difference was found between CON and HS weight (640.6 ± 62.8 N and 640.9 ± 62.9 N, respectively, p=0.3815). The metrological tests suggest that the statistical differences found are related to the force plate measuring errors in every pre-established time interval. The 45 g (0.44 N) difference found between pretest and post-test lies within the uncertainty range identified for the equipment (± 110 g or 1.08 N). In conclusion, a 30-second headstand has no significant effect on registered body weight. The small variations obtained were due to equipment-associated measuring errors. This experiment offers systematic empirical evidence to aid in the elimination of this unjustified practice among the wrestling community.