title: Rapid weight-loss impairs simulated riding performance and strength in jockeys: implications for making-weight.
abstract: Despite the performance concerns of dehydration in other sports, there are currently no data on the effects of rapid weight-loss on the physical and cognitive performance of jockeys in a sport-specific context. In a randomised crossover design, eight Great Britain (GB) male licensed jockeys were assessed for chest strength, leg strength, simulated riding performance (assessed by maximum pushing frequency on a mechanical riding simulator during the final two furlongs of a simulated 2 mile race) and simple reaction time after performing 45 min of exercise, during which euhydration was maintained (Control trial) or induced 2% dehydration (Rapid Weight-Loss trial). Reductions in both chest (-13.8 ± 3.03% vs. 0.62 ± 1.04%) and leg strength (-4.8 ± 4.8% vs. -0.56 ± 2.5%) were greater in Rapid Weight-Loss compared with Control (P < 0.01 and P = 0.04, respectively). Similarly, reductions in simulated riding performance were also greater (P = 0.05) in Rapid Weight-Loss (-2.8 ± 4.0%) compared with Control (-0.07 ± 1.5%), whereas there were no significant changes (P = 0.14) in simple reaction time. We conclude that a 2% reduction in body mass, as achieved by 45 min of moderate-intensity exercise undertaken in a sweatsuit (a common method of inducing acute dehydration by jockeys), significantly impairs maximum pushing frequency during a simulated race. In addition, the observed reductions in strength may also increase the occupational hazards associated with race riding.
authors.affiliation: a Research Institute for Sport and Exercise Sciences , Liverpool John Moores University , Liverpool , UK.
authors.forename: George
authors.initials: G
authors.lastname: Wilson
authors.forename: Malcolm B
authors.initials: MB
authors.lastname: Hawken
authors.forename: Ian
authors.initials: I
authors.lastname: Poole
authors.forename: Andy
authors.initials: A
authors.lastname: Sparks
authors.forename: Simon
authors.initials: S
authors.lastname: Bennett
authors.forename: Barry
authors.initials: B
authors.lastname: Drust
authors.forename: James
authors.initials: J
authors.lastname: Morton
authors.forename: Graeme L
authors.initials: GL
authors.lastname: Close
mesh_terms: D000818:Animals; D054874:Athletic Performance / Q000502:physiology*; D018592:Cross-Over Studies; D003681:Dehydration / Q000150:complications*; D015444:Exercise / Q000502:physiology*; D006736:Horses; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology; D053580:Muscle Strength; D013177:Sports / Q000502:physiology*; D013546:Sweating / Q000502:physiology*; D015431:Weight Loss / Q000502:physiology*