The present invention provides a to method for reinforcing a wind turbine blade, such as a root end. The root end comprises a first and a second bushing for attaching the wind turbine blade to a wind turbine hub, the bushings being located between an inner sidewall of the root end and an outer sidewall of the root end, the bushings being separated by retaining material, the method comprising forming a first injection channel in the retaining material; forming a first pressure release channel in the first retaining material, wherein the first pressure release channel is formed to be in fluid communication with the first injection channel in a region between the inner sidewall and the outer sidewall; and injecting adhesive material into the first injection channel at least until adhesive material enters the formed first pressure release channel. The invention also provides a wind turbine blade having a root end that has been reinforced using such a method. Further aspects are provided.