Acute effects of gluteal warm up on knee valgus motion during jumping and landing in adolescent females

This study aimed to assess the effect of a ninety second gluteal warm-up (GW) on knee valgus motion during take-off and landing tasks in adolescent females; assess its efficacy on jump performance; and assess whether those with Generalised Joint Hypermobility (GJH) respond differently. GJH has been linked to greater knee injury risk and gluteal muscle action has been linked to a reduction of knee valgus motion, a known factor in knee injury, as well as improved jump performance. Where warm-up time is limited, a 90 second warm-up that activates the gluteal muscles could prove very useful and this study sought to establish whether this warm-up could acutely affect physical performance and whether it has potential use in injury prevention by reducing excessive knee-valgus motion. Twenty-three active females (age 16 ± 1.38 years, weight 58.43 ± 12.81kg) participated. Joint mobility was assessed using a Beighton’s test (scores ≥ 4 being classified as GJH). Participants attended two sessions and carried out both the GW and a standard dynamic warm up (DW). CMJ height was measured using Pasco force platforms and analysed through SparkVue software. Knee valgus angles were recorded during CMJ take-off and landing, as well as drop landings from a 32cm high platform. Angles were assessed using Kinovea 2D video analysis software. Repeated measures ANOVA was used to assess the effects of warm-up on knee valgus motion and jump height. Warm-up did not significantly affect jump height or knee valgus motion and those with GJH did not on the whole, respond differently to their non-hypermobile counterparts. Non-hypermobiles did respond to a gluteal warm-up with a reduction in knee valgus during take-off but no difference during landing was found. In conclusion, the short gluteal warm-up performed equally well when compared to a longer dynamic warm-up suggesting it may be useful in sports settings where speed of preparation is paramount, but it did not appear to be any better at acutely affecting knee valgus mechanics in those with GJH. Key words: Hypermobility, Lower Limb Kinematics, Injury Prevention