The adductor strengthening programme prevents groin problems among male football players: a cluster-randomised controlled trial

Key points

1. 01Risk of reporting any groin problem was 41% lower in the intervention group (OR 0.59, 95% CI 0.40 to 0.86, p=0.008)
2. 02Average weekly groin problem prevalence was 13.5% in the intervention group versus 21.3% in the control group
3. 03The programme uses a single exercise with three progression levels and requires less than 5 minutes per weekly in-season session
4. 04Compliance averaged about 70% of the recommended protocol in both preseason and competitive season phases
5. 05The per-protocol analysis showed an even larger benefit: 47% lower risk (OR 0.53, 95% CI 0.36 to 0.78, p=0.001)

How it was conducted

Design

Cluster-randomised controlled trial (35 semiprofessional Norwegian football teams, February to October 2016)

Participants

652 players enrolled; 489 included in intention-to-treat analysis (intervention n=247, control n=242)

Intervention

Adductor Strengthening Programme using the Copenhagen Adduction exercise (3 progression levels), 2-3 times per week for 6-8 weeks preseason, then once per week for 28-week competitive season

Control

Instructed to train as normal

Primary outcome

Weekly prevalence of all groin problems during the competitive season, measured with the OSTRC Overuse Injury Questionnaire

Secondary outcome

Weekly prevalence of substantial groin problems (moderate or severe reductions in training or performance, or inability to participate)

What they found

• Average weekly prevalence of all groin problems: 13.5% (95% CI 12.3%-14.7%) in intervention vs 21.3% (95% CI 20.0%-22.6%) in control
• ITT analysis: 41% lower risk of groin problems in the intervention group (OR 0.59, 95% CI 0.40 to 0.86, p=0.008)
• Per-protocol analysis: 47% lower risk (OR 0.53, 95% CI 0.36 to 0.78, p=0.001)
• Substantial groin problems: 5.7% (95% CI 5.1%-6.3%) intervention vs 8.0% (95% CI 7.5%-8.5%) control; 18% lower risk but not significant (OR 0.82, 95% CI 0.51 to 1.33, p=0.42)
• Cumulative incidence of all groin problems: 55% intervention vs 67% control
• Cumulative incidence of substantial groin problems: 28% intervention vs 37% control
• Mean preseason compliance: 73% of recommended sessions; in-season compliance: 0.7 sessions per week (70% of recommendation)
• No adverse events reported

Limitations

• Blinding of players, coaches, and principal investigator was not possible, introducing potential performance bias
• Retrospective questionnaire completion during the last month of the study may have introduced recall bias
• Compliance was self-reported and could not be independently verified
• No detailed clinical diagnosis was obtained for most reported groin problems, limiting classification by injury entity

Why it matters

For patients

Football players can substantially cut their chance of developing groin pain during a season by adding a simple adductor exercise to their warm-up routine, with very low time cost and no reported adverse effects.

For clinicians

Prescribing the Adductor Strengthening Programme as part of football training warm-up is a practical, evidence-backed strategy for groin injury prevention; the in-season dose is one short session per week.

For readers

This is the first RCT to show that a groin-targeted exercise programme significantly reduces groin problem prevalence in male footballers, supporting its inclusion in structured warm-up protocols such as the FIFA 11+.