Nordic hamstring exercise training alters knee joint kinematics and hamstring activation patterns in young men

Area of Science:

• Biomechanics
• Exercise Physiology
• Sports Science

Background:

• The Nordic hamstring exercise (NHE) is a popular method for eccentric hamstring training.
• Understanding the adaptations to NHE is crucial for optimizing training protocols.
• Previous research has explored various aspects of hamstring training, but specific kinematic and neuromuscular adaptations to a dedicated NHE program require further investigation.

Purpose of the Study:

• To investigate the kinematic and muscle activation adaptations during the Nordic hamstring exercise (NHE).
• To evaluate the effects of a 6-week eccentric hamstring training program solely utilizing the NHE.
• To explore potential mechanisms behind improved hamstring muscle control following NHE training.

Main Methods:

• Twenty-nine healthy males were recruited and randomly assigned to either a control group (CG) or an intervention group (IG).
• The intervention group (IG) underwent a 6-week training program focused exclusively on the Nordic hamstring exercise (NHE).
• Kinematic and electromyographic (EMG) data were collected during NHE performance to assess muscle activation and movement patterns.

Main Results:

• The 6-week eccentric hamstring training program significantly improved eccentric hamstring muscle strength (202.4 vs. 177.4 nm, p = 0.0002).
• Optimized kinematic parameters were observed, including increased control of the forward fall component of the NHE (73.7° vs. 68.1°, p = 0.022).
• Significant increases in hamstring electromyographic activity (EMG) were noted, indicating enhanced neuromuscular adaptation (p < 0.05, Cohen's d > 1.25).

Conclusions:

• A 6-week eccentric hamstring training program using the NHE can lead to substantial improvements in eccentric hamstring strength.
• The NHE program enhances neuromuscular control and optimizes movement kinematics during the exercise.
• These findings provide insight into the mechanisms underlying improved hamstring muscle control during eccentric contractions through dedicated NHE training.