Validity of an on-field re-adaptation program following a hamstring injury in professional soccer

Key points

1. 01All 13 program items passed expert validation with Aiken's V between 0.78 and 0.98
2. 0219 La Liga players returned to play in a mean of 22.42 (SD 2.32) days after a grade II hamstring strain
3. 03No reinjuries were recorded in the 6 months following return to play
4. 04The program progresses from gym mobilization and strengthening to on-field sport-specific drills over approximately 17 days
5. 05Drills incorporate repeated sprint ability, acceleration-deceleration reeducation, and neuromuscular control of the core and lower limbs

How it was conducted

Design

Prospective longitudinal technical report: expert validation followed by application in professional players

Validation panel

15 strength and conditioning and rehabilitation fitness coaches, mean experience 15.40 (SD 1.57) years in elite clubs and national teams across Europe

Player sample

19 male professional soccer players from Spanish First Division (La Liga), age 24.23 (SD 5.36) years, diagnosed with grade II hamstring strain injury confirmed by MRI and/or ultrasound

Intervention

13-item on-field program beginning on day 8 post-injury, preceded by gym mobilization and percutaneous needle electrolysis; drills arranged in progressively increasing complexity

Validation method

Aiken's V content validity coefficient with 95% confidence intervals; minimum threshold of 0.75 required for validity

Primary outcomes

Aiken's V for each of the 13 items and number of days to return to competitive play

What they found

• All 13 items were rated valid by experts with Aiken's V between 0.78 and 0.98 (95% CI range 0.63-1.00 across items)
• The highest-rated items (Aiken's V > 0.90) were items 3, 4, 6, 7, 8, 9, 11, 12, and 13, which incorporated repeated sprint ability and acceleration-deceleration patterns
• Item 6 received the highest rating with Aiken's V of 0.98 (95% CI 0.88-1.00)
• Item 1 received the lowest rating with Aiken's V of 0.78 (95% CI 0.63-0.88)
• Players returned to competitive play in 22.42 (SD 2.32) days
• No reinjuries were reported in the 6 months following return to play in any of the 19 players

Limitations

• No control group: return-to-play time cannot be attributed to this program versus standard care
• Small sample of 19 players with no comparison to other rehabilitation protocols
• Reinjury follow-up was limited to 6 months and relied on clinical reporting without standardized monitoring
• Pre-injury and post-injury GPS performance data were not compared, so functional recovery level is unknown

Why it matters

For patients

Professional soccer players with a grade II hamstring strain may be able to follow a structured on-field program and return to competition in about 3 weeks without reinjury in the short term.

For clinicians

The 13-item program provides a sport-specific, progressively loaded framework validated by expert consensus that can guide on-field rehabilitation decisions after hamstring strain in elite soccer.

For readers

This is a small, uncontrolled technical report; the validation is based on expert opinion rather than a clinical trial comparing outcomes, so results should be interpreted with caution.