DYNAMIC HIP ADDUCTION, ABDUCTION AND ABDOMINAL EXERCISES FROM THE HOLMICH GROIN-INJURY PREVENTION PROGRAM ARE INTENSE ENOUGH TO BE CONSIDERED STRENGTHENING EXERCISES - A CROSS-SECTIONAL STUDY

Abstract

Background: Training intensity is an important variable in strength training and above 80% of one repetition maximum is recommended for promoting strength for athletes. Four dynamic and two isometric on-field exercises are included in the Hölmich groin-injury prevention study that initially failed to show a reduction in groin injuries in soccer players. It has been speculated that exercise-intensity in this groin-injury prevention program was too low to induce the strength gains necessary to protect against groin-related injuries.

Purpose: To estimate the intensity of the six exercises from the Hölmich program using electromyography (EMG) and possibly categorize them as strength-training exercises.

Study design: Cross-sectional study.

Methods: 21 adult male soccer players training >5 hours weekly were included. Surface-EMG was recorded from adductor longus, gluteus medius, rectus abdominis and external obliques during isometric adduction against a football placed between the ankles (IBA), isometric adduction against a football placed between the knees (IBK), folding knife (FK), cross-country skiing on one leg (CCS), adduction partner (ADP) and abduction partner (ABP). The EMG-signals were normalized (nEMG) to an isometric maximal voluntary contraction for each tested muscle.

Results: Adductor longus activity during IBA was 84% nEMG (95% CI: 70-98) and during IBK it was 118% nEMG (95% CI 106-130). For the dynamic exercises, ADP evoked 87% nEMG (95% CI 69-105) in adductor longus, ABP evoked 88% nEMG (95% CI 76-100) in gluteus medius, FK evoked 82% nEMG (95% CI 68-96) rectus abdominis, and 101% nEMG (95% CI 85-118) in external obliques. During CSS < 37% nEMG was evoked from all muscles.

Conclusion: These data suggest that exercise-intensity of all the six investigated exercises in the Hölmich groin injury prevention program, except cross-county skiing, is sufficient to be considered strength-training for specific muscle groups in and around the groin region.

Level of evidence: 3.

Keywords: Abdominals; adductor longus; electromyography; gluteus medius; soccer.

Figure 1.

The six included exercises: a = ”isometric adduction against a football placed between the ankles”; b = ”isometric adduction against a football placed between the knees”; c = “folding knife”; d = “crosscountry skiing on one leg”; e = “adduction partner” performed by the player to the left; f = “abduction partner” performed by the player to the left.

Figure 1.

Mean peak of median nEMG with standard error for adductor longus, gluteus medius, external obliques and rectus abdominis during the exercises. nEMG = Normalized electromyography.