Slowly does it: The effect of attentional focus on biomechanical and neuromuscular factors during the Nordic hamstring exercise in young female athletes

Abstract

The inclusion of the Nordic hamstring exercise (NHE) is recommended for athletic populations to help reduce hamstring and ACL injury risk via increasing eccentric hamstring strength. However, previous research is yet to identify effective verbal cues to optimise NHE performance. Therefore, this study examined whether kinetic, kinematic, and neuromuscular responses differ when using an external-distal (DIST), external-proximal (PROX), internal (INT) or neutral cue (CON). Twenty-two trained young female athletes (16–18 years) performed three NHE repetitions per cue in a randomised, crossover, counterbalanced design. Peak force, knee breakpoint angle, peak knee velocity and electromyography of the semitendinosus and bicep femoris long-head muscles were recorded. Peak force was significantly higher in CON and DIST compared with INT and PROX (∼10–16 N, d = 0.58–0.72), while CON produced a lower breakpoint angle than other cues (∼9–12°, d = 0.95–1.24), indicating greater range of motion. CON also elicited the highest peak knee velocity (∼31–38°·s⁻¹, d = 1.45–1.92) and greater semitendinosus activation (∼10–14%, d = 0.32–0.42), with no differences observed for biceps femoris activation. Overall, the CON cue consistently enhanced kinetic, kinematic, and neuromuscular responses during the NHE. The instruction “lower yourself slowly to the ground” therefore appears to be an effective strategy to further enhance NHE performance. Coaches prescribing the NHE within injury-prevention programmes for youth female athletes can adopt this combined exercise-and-cue approach to develop eccentric hamstring strength.