Table 1

Progressions in sets and repetitions through the exercise programme

Target week	Sessions	Sets per side	Repetitions	Time under tension per repetition (s)	Total time under tension (per leg, s)	Original CA exercise level
1	2	2	6	20	240	Level 1
2	2	2	6	20	240	Level 2
3	2	3	6	20	360	Level 3
4	2	3	8	20	480	Level 4
5	2	3	8	20	480	Level 5
6	2	3	6	3 s concentric 3 s eccentric	108	Level 6 (full CA)
7	2	3	8	3 s concentric 3 s eccentric	144	Level 6 (full CA)
8	2	3	10	3 s concentric 3 s eccentric	180 s	Level 6 (full CA)

Levels 1–5 are isometric muscle contractions progressing in difficulty. Level 6 is a traditional CA exercise and is an eccentric/concentric exercise shown to prevent groin problems,5 increase EHAD strength and EHAD:EHAB ratio.13
Level 1: participants performed a supported isometric adduction hold off a 30 cm box in a short-lever side-lying position. The participants then raise their pelvis from the floor, keeping their lower knee on the ground for support (figure 1A).
Level 2: participants lifted their supporting leg and brought their knees together (figure 1B).
Level 3: participants progressed to a long lever-supported isometric hold with their foot becoming the contact point for the hold. They then lifted their pelvis, keeping their lower leg foot on the floor for support (figure 1C).
Level 4: participants lifted their supporting leg and brought their knees together in a long-lever position (figure 1D).
Level 5: the box height was increased to hip height as determined by the original CA exercise14 (figure 1E).
Level 6: participants used a partner to perform a dynamic eccentric exercise. This involved their partner holding the upper leg at hip height and supporting the ankle and knee joints and the participant lowering their pelvis towards the ground over a period of 3 s. The participant then lowered their leg while supporting themselves and returned to the start position14 (figure 1F).
CA, Copenhagen adduction; EHAB, eccentric hip abduction; EHAD, eccentric hip adduction.