‍Background/Purpose 

Hamstring strains are common in sports such as soccer. There are a variety of hamstring strength exercises, but each will provide slightly different loading and muscle activation patterns. Therefore, the purpose of this article was to compare hamstring muscle use during different hamstring strength training exercises in professional soccer players.  

Methods 

36 professional soccer players from elite Spanish U18 and reserve teams were randomly assigned to perform one of four different hamstring exercises: 1) Nordic hamstring exercise, 2) flywheel leg curl, 3) Russian belt, or 4) conic-pulley hip extension exercise. Each group performed 4 sets of 8 repetitions of their assigned exercise with maximal intensity. Functional MRI was used to measure T2 relaxation time of individual muscles before and immediately after each set. Changes in T2 provide an indication of muscle use during the exercise.  

Results 

The flywheel leg curl had the greatest changes in T2 for several muscles, including the gracilis (95%), semitendinosus (65%), biceps femoris short head (51%) and biceps femoris long head (14%). Notably, it had the highest T2 for the biceps femoris short head and semitendinosus compared to all other exercises. Nordic hamstring exercise also had significant activation of semitendinosus, biceps femoris short head, and gracilis.  

Key Takeaways 

• The flywheel leg curl had high muscle activation across multiple muscles of the hamstrings and their synergists (e.g., gracilis), including those that play an important role in hamstring strain injuries.  

• Flywheel exercises also emphasize loading during the eccentric to concentric transition point, which may be useful for preparing the tissues for demanding portions of sprinting (e.g., early stance phase).  

• Exercises that prioritize knee flexion (flywheel leg curl and Nordic hamstring) resulted in better muscle activation of hamstring muscles than hip extension exercises (Russian belt and conic-pulley hip extension). With flywheel leg curl providing the most well-rounded muscle activation across the various muscles measured in this study.   

These results provide context to why several studies have found flywheel leg curls to be a promising strategy for reducing hamstring strain injury frequency and severity (Askling et al., 2003; de Hoyo et al., 2015).

Link:
https://www.thieme-connect.com/products/ejournals/abstract/10.1055/s-0042-100290