Implementing the Copenhagen Adductor Exercise and Nordic Hamstring Exercise in West African Academy Soccer Players: An Intervention Study.

Background: This study implemented the Copenhagen Adductor Exercise (CAE) and Nordic Hamstring Exercise (NHE) to examine 1) whether CAE and NHE interventions are associated with adductor and hamstring strength gains in youth African male soccer players and 2) whether strength changes after a rest period and secondary intervention.

Study design: Pre-post intervention study.

Methods: Forty-four African elite male academy players (age 14.7±1.5 [12-18] years) participated in twice weekly CAE and NHE interventions for 8- and 10-week periods separated by a 4-week rest. Long lever adductor squeeze strength and prone isometric hamstring strength were measured with mixed-effects linear regression models to observe strength changes over time.

Results: Ninety-six and 95% of CAE and NHE sessions were completed in each intervention, with no adverse events related to the execution of the exercises. Adductor squeeze strength increased during the first intervention (baseline 3.23 [2.99-3.47] N/kg, post-intervention 3.53 [3.30-3.76] N/kg, p=0.911) and was maintained following the rest period (3.52 [3.27-3.76] N/kg, p=0.999) and second intervention (3.60 [3.35-3.84] N/kg, p=0.002). Hamstring strength improved during the first intervention (baseline 4.95 [4.42-5.49] N/kg, post-intervention 5.48 [4.95-6.02] N/kg, p<0.001), decreased to baseline during the rest period (4.98 [4.44-5.53] N/kg, p=0.996), and did not improve during the second intervention (5.01 [4.46-5.55] N/kg, p=0.978).

Conclusion: CAE and NHE interventions can be implemented at an elite African academy with high compliance. Adductor and hamstring strength improved in the first intervention, with no further improvements in the second intervention. Secondary interventions therefore should include higher exercise volume or load to improve longitudinal adductor and hamstring strength.

Level of evidence: Level III (Cohort Study).