There is a lack of definitive evidence supporting deficits in voluntary activation in participants with prior hamstring injury, moreover it remains unknown if spinal mechanisms contribute to suspected deficits. To determine the effect of prior hamstring strain injury on knee flexor concentric and eccentric strength, voluntary activation, surface electromyographic activity (sEMG), stretch and tendon reflex amplitudes. Twenty-five participants were recruited, twelve with a history of unilateral hamstring strain injury of at least moderate severity. Voluntary activation, strength and sEMG activity were recorded during maximal eccentric and concentric knee flexor contractions at 60/s. Stretch and tendon reflexes were also recorded at rest. Previously injured limbs exhibited lower levels of voluntary activation (mean difference=-24.1%[95% CI=-34.1 to-14.0%], p&0. 001) strength (mean difference vs. control group=-0.37 Nm/kg [95% CI=-0.71 to-0.03 Nm/kg], p= 0.03) and normalised sEMG (mean difference=-17%[95% CI=-32 to-2%], p= 0.02) during maximal eccentric knee flexor contractions compared to control group. No such differences were seen in concentric contractions. Stretch reflexes (mean difference=-3.8%[95% CI=-6.8 to-0.8], p= 0.02) and tendon reflexes (mean difference=-13%[95% CI=-26 to 0%], p= 0.04) were also lower in previously injured compared to control biceps femoris muscles. Moderate to severe hamstring strain injury is associated with long-term deficits in voluntary activation during maximal eccentric contraction. Hamstring injury history is also associated with deficits in stretch reflex and tendon reflex amplitude.