OBJECTIVE:
The objective of this study was to examine the effects of an 8-week progressive resistance training program on hip joint muscles' strength measures, using the Copenhagen adduction (CA) and the sliding hip (SH) exercises.

DESIGN:
Prospective randomized controlled trial.

SETTING:
Sport training and medical centers.

PARTICIPANTS:
Forty-two young male football athletes (age 17.5 ± 1.1 years; height 178.3 ± 3.2 cm; body mass 66.1 ± 8.6 kg) allocated to a CA, SH, and matched control (C) group.

INTERVENTIONS:
Two weekly sessions of CA and SH.

MAIN OUTCOMES MEASURES:
Maximal eccentric strength test for the hip adductor (EHAD) and maximal eccentric strength test for the hip abductor (EHAB) muscles, and the relative EHAD/EHAB ratio assessed through a break test in the side-lying position.

RESULTS:
No significant differences between groups were found at baseline for any of the assessed variables (all P > 0.053). The CA group had a significant strength increase in the right and left leg (d = 2.11, d = 1.9, respectively). The SH group also had a significant strength increase in the right and left leg (d = 1.68 and d = 1.67, respectively). The CA group presented EHAD/EHAB improvements in the right and left leg (d = 0.84 and d = 1.14, respectively). The SH group also presented EHAD/EHAB improvements in the right and left leg (d = 1.34 and d = 1.44, respectively).

CONCLUSIONS:
Both exercises' protocols were effective in inducing significant increases on EHAD, EHAB, and EHAD/EHAB ratio when compared with the control group. Practitioners should be aware of the training effectiveness of both protocols.