Anterior Cruciate Ligament Injury Is Associated With Fast Twitch Hamstring Muscle Fiber Typology.

Area of Science:

• Sports Medicine
• Biophysics
• Muscle Physiology

Background:

• Anterior cruciate ligament (ACL) injuries are common in male football players.
• Muscle fiber type (MFT) distribution influences athletic performance and hamstring injury risk.
• Hamstring muscles act as biomechanical synergists to the ACL.

Purpose of the Study:

• To investigate the relationship between hamstring MFT distribution and ACL injury in football players.
• To determine if hamstring carnosine content, an indicator of MFT, differs between players with and without ACL injuries.

Main Methods:

• Proton magnetic resonance spectroscopy (¹H-MRS) was used to evaluate hamstring MFT distribution.
• Thirty-seven male football players with ACL injuries and 49 matched controls participated.
• MFT distribution was estimated via relative carnosine content analysis.

Main Results:

• Significant differences in hamstring carnosine content were observed between ACL injury and control groups (p=0.011).
• The ACL injury group exhibited higher average carnosine content (0.204 ± 0.011 AU) compared to the control group (0.169 ± 0.008 AU).
• Estimated FT fiber dominance was higher in the ACL group (27%) than in the control group (18%).

Conclusions:

• ACL injury history is significantly associated with hamstring muscle carnosine content.
• Higher fast-twitch (FT) fiber dominance may be a contributing factor or consequence of ACL injury.
• Further prospective research is needed to establish a causal link between intramuscular carnosine content and ACL injury risk for injury prevention strategies.