Analysis of the Hamstring Muscle Activation During two Injury Prevention Exercises

Abstract

The aim of this study was to perform an electromyographic and kinetic comparison of two commonly used hamstring eccentric strengthening exercises: Nordic Curl and Ball Leg Curl. After determining the maximum isometric voluntary contraction of the knee flexors, ten female athletes performed 3 repetitions of both the Nordic Curl and Ball Leg Curl, while knee angular displacement and electromyografic activity of the biceps femoris and semitendinosus were monitored. No significant differences were found between biceps femoris and semitendinosus activation in both the Nordic Curl and Ball Leg Curl. However, comparisons between exercises revealed higher activation of both the biceps femoris (74.8 ± 20 vs 50.3 ± 25.7%, p = 0.03 d = 0.53) and semitendinosus (78.3 ± 27.5 vs 44.3 ± 26.6%, p = 0.012, d = 0.63) at the closest knee angles in the Nordic Curl vs Ball Leg Curl, respectively. Hamstring muscles activation during the Nordic Curl increased, remained high (>70%) between 60 to 40° of the knee angle and then decreased to 27% of the maximal isometric voluntary contraction at the end of movement. Overall, the biceps femoris and semitendinosus showed similar patterns of activation. In conclusion, even though the hamstring muscle activation at open knee positions was similar between exercises, the Nordic Curl elicited a higher hamstring activity compared to the Ball Leg Curl.

Is neuromuscular inhibition detectable in elite footballers during the Nordic hamstring exercise?

“…Despite no differences in BF activation between groups, higher levels of BF muscle activation were found at the more flexed (90-30º epoch) compared to the 30-0º epoch (Figure 2). These results agree with Iga et al (2012) and Monajati et al (2017) who demonstrated maximal muscle activity as occurring between 90-30º and 60-40º of knee flexion, respectively. 29,30 Our findings further support the effectiveness of the NHE to elicit high levels of muscle activation (96-114%) during the exercise's first 60º of knee excursion, which falls to and moderate levels of activation (57-75%) during the terminal 30º at long muscle lengths.…”

“…These results agree with Iga et al (2012) and Monajati et al (2017) who demonstrated maximal muscle activity as occurring between 90-30º and 60-40º of knee flexion, respectively. 29,30 Our findings further support the effectiveness of the NHE to elicit high levels of muscle activation (96-114%) during the exercise's first 60º of knee excursion, which falls to and moderate levels of activation (57-75%) during the terminal 30º at long muscle lengths. 31 Previous research suggests that in the presence of reduced BF activation following injury, changes in the relative contribution of other muscle synergists may represent a compensatory mechanism against neuromuscular inhibition.…”

“…It would then appear reduced GM activation, a recognised risk factor for hamstring strain injury within footballers 19 is detectable during the NHE. Additionally, at this more extended knee position during the NHE, authors suggest the BF to be primarily resisting an anterior pelvic tilt (relative hip flexion) moment as opposed to knee extension, 30 and therefore acting as a synergist to the hip extensors including the GM. 32 The activation ratios reported for the previously injured players may represent a greater neuromuscular demand placed upon the BF to attenuate the anterior pelvic tilt moment.…”

Posterior Thigh Isometric Force Measurement with Extended Knee

“…Lower limb movement analysis has been studies to determine the sequence of contraction of posterior and anterior muscles of the thigh [1]. Moreover, muscle force characterization is increasingly important in rehabilitation and sports medicine 4].…”

“…Lower limb movement analysis has been addressed in several studies to determine the sequence of contraction of posterior and anterior muscles of the thigh [1] muscle force characterization is increasingly important in rehabilitation and sports m [2], especially for elite athletes [3, injuries occur during sports when the athlete, during terminal swing phase of running [5] extends the lower limb beyond limits. Rehabilitation is very important after injuries or surgical repair.…”