Effectiveness of a warm-up programme to reduce injuries in youth volleyball players : a quasi-experiment

OBJECTIVES : To establish the effectiveness of the ‘VolleyVeilig’ programme on reducing injury rate, injury burden and injury severity in youth volleyball players. METHODS : We conducted a quasi-experimental prospective study over one season of youth volleyball. After randomisation by competition region, we instructed 31 control teams (236 children, average age 12.58±1.66) to use their usual warm-up routine. The ‘VolleyVeilig’ programme was provided to 35 intervention teams (282 children, average age 12.90±1.59). This programme had to be used during each warm-up before training sessions and matches. We sent a weekly survey to all coaches, collecting data on each player’s volleyball exposure and injuries sustained. Multilevel analyses estimated differences in injury rates and burden between both groups, and we used non-parametric bootstrapping to compare the differences in injury numbers and injury severity. RESULTS : We found an overall reduction in injury rates of 30% for intervention teams (HR 0.72; 95% CI 0.39 to 1.33). Detailed analyses revealed differences for acute (HR 0.58; 95% CI 0.34 to 0.97) and upper extremity injuries (HR 0.41; 95% CI 0.20 to 0.83). Compared with control teams, the intervention teams had a relative injury burden of 0.39 (95% CI 0.30 to 0.52) and a relative injury severity of 0.49 (95% CI 0.03 to 0.95). Only 44% of teams fully adhered to the intervention. CONCLUSION : We established that the ‘VolleyVeilig’ programme was associated with reduced acute and upper extremity injury rates and lower injury burden and severity in youth volleyball players. While we advise implementation of the programme, programme updates to improve adherence are needed.http://bjsm.bmj.comhj2023Sports Medicin

Effectiveness of a warm-up programme to reduce injuries in youth volleyball players: A quasi-experiment

Objectives To establish the effectiveness of the € VolleyVeilig' programme on reducing injury rate, injury burden and injury severity in youth volleyball players. Methods We conducted a quasi-experimental prospective study over one season of youth volleyball. After randomisation by competition region, we instructed 31 control teams (236 children, average age 12.58±1.66) to use their usual warm-up routine. The € VolleyVeilig' programme was provided to 35 intervention teams (282 children, average age 12.90±1.59). This programme had to be used during each warm-up before training sessions and matches. We sent a weekly survey to all coaches, collecting data on each player's volleyball exposure and injuries sustained. Multilevel analyses estimated differences in injury rates and burden between both groups, and we used non-parametric bootstrapping to compare the differences in injury numbers and injury severity. Results We found an overall reduction in injury rates of 30% for intervention teams (HR 0.72; 95% CI 0.39 to 1.33). Detailed analyses revealed differences for acute (HR 0.58; 95% CI 0.34 to 0.97) and upper extremity injuries (HR 0.41; 95% CI 0.20 to 0.83). Compared with control teams, the intervention teams had a relative injury burden of 0.39 (95% CI 0.30 to 0.52) and a relative injury severity of 0.49 (95% CI 0.03 to 0.95). Only 44% of teams fully adhered to the intervention. Conclusion We established that the € VolleyVeilig' programme was associated with reduced acute and upper extremity injury rates and lower injury burden and severity in youth volleyball players. While we advise implementation of the programme, programme updates to improve adherence are needed

Quantitative kinetic analysis of nucleolar breakdown and reassembly during mitosis in live human cells

One of the great mysteries of the nucleolus surrounds its disappearance during mitosis and subsequent reassembly at late mitosis. Here, the relative dynamics of nucleolar disassembly and reformation were dissected using quantitative 4D microscopy with fluorescent protein-tagged proteins in human stable cell lines. The data provide a novel insight into the fates of the three distinct nucleolar subcompartments and their associated protein machineries in a single dividing cell. Before the onset of nuclear envelope (NE) breakdown, nucleolar disassembly started with the loss of RNA polymerase I subunits from the fibrillar centers. Dissociation of proteins from the other subcompartments occurred with faster kinetics but commenced later, coincident with the process of NE breakdown. The reformation pathway also follows a reproducible and defined temporal sequence but the order of reassembly is shown not to be dictated by the order in which individual nucleolar components reaccumulate within the nucleus after mitosis