Acute non-contact lower limb injuries, especially hamstring strains, are a persistent issue in team sports.
Traditional approaches look for linear relationships (e.g., weak hamstrings = injury), but injuries are often caused by interacting factors, not isolated ones.
This study used systems thinking and structural equation modeling to better understand the complex web of risk factors contributing to these injuries.
Can we use systems-based approaches to identify and model the dynamic interrelationships among risk factors that lead to acute non-contact lower limb injuries, especially hamstring strains, in team sports?
What Did the Researchers Do?
The authors conducted two studies: one qualitative, one quantitative.
Qualitative (Causal Loop Diagram - CLD)
- Used literature and seven structured group modeling sessions.
- Participants: 8 experts (academics, clinicians, team staff, and a system dynamics expert).
- Outcome: Created the Hamstring Injury Causal Loop Diagram (HI-CLD) showing how 65 internal/external/institutional factors interact.
Quantitative (PLS-SEM)
- Prospective cohort study of 99 football players.
- Preseason testing included: strength, flexibility, fatigue, muscle endurance, EMG activation, and injury history.
- Athletes tracked for injury occurrence throughout the season.
- Two structural equation models built: one for hamstring injuries, one for all non-contact lower limb injuries.
What Were the Results?
Qualitative Findings
- 65 interconnected risk factors were mapped.
- Diagram included feedback loops: balancing (B) and reinforcing (R).
- Influences span athlete (e.g., fatigue), team (e.g., coaching strategies), and institutional (e.g., scheduling) levels.
Quantitative Findings
Hamstring injuries
- Directly influenced by age > 24 and isometric hamstring strength asymmetries.
- Indirectly influenced by hamstring/core endurance, which impact strength asymmetries.
All non-contact injuries
- Directly influenced by strength asymmetries and prior injuries.
- Age moderated the effect of asymmetries—older athletes were more impacted.
What Does This Mean?
- Injury risk is multifactorial and dynamic—think systems, not symptoms.
- Endurance (core and hamstring) may not be direct risk factors, but they matter due to their effect on strength balance.
- Older athletes and those with prior injuries need more individualized care.
- Strength asymmetries are a clear, measurable, and modifiable target.
Limitations
- The cohort was limited to 99 football players in one country.
- Findings may not generalize across sports, genders, or age ranges.
- PLS-SEM shows relationships, not true causality.
- CLD is based on expert consensus and literature—not real-time dynamic data.
Coach’s Takeaway
- Treat injury risk as a network of factors, not isolated variables.
- Focus on reducing asymmetries and boosting endurance—especially for older or previously injured athletes.
- Use field-friendly screening tools to track fatigue, coordination, and workload deviations (e.g., GPS, RPE).
Reference
Liveris, N.I. (2025). Applying systems thinking approaches to investigate the complex interrelationships of risk factors affecting acute non-contact lower limb injuries in team sports. Br J Sports Med.
