Effects of early progressive eccentric exercise on muscle size and function after anterior cruciate ligament reconstruction: a 1-year follow-up study of a randomized clinical trial.
OBJECTIVE
The authors previously reported that focused eccentric resistance training during the first 15 weeks following anterior cruciate ligament reconstruction (ACL-R) induced greater short-term increases in muscle volume, strength, and measures of function relative to standard rehabilitation. The purpose of this study was to evaluate the effects of early progressive eccentric exercise on muscle volume and function at 1 year after ACL-R.


METHODS
Forty patients who had undergone an ACL-R were randomly assigned to 1 of 2 groups: a group that received early progressive eccentric exercise (n=20) and a group that received standard rehabilitation (n=20). Seventeen participants in the eccentric exercise group and 15 participants in the standard rehabilitation group completed a 1-year follow-up. Magnetic resonance images of the thighs were acquired 1 year after ACL-R and compared with images acquired 3 weeks after surgery. Likewise, routine knee examinations, self-report assessments, and strength and functional testing were completed 1 year after surgery and compared with previous evaluations. A 2-factor analysis of variance for repeated measures (group x time) was used to analyze the data.


RESULTS
Compared with the standard rehabilitation group, improvements in quadriceps femoris and gluteus maximus muscle volume in the involved lower extremity from 3 weeks to 1 year following ACL-R were significantly greater in the eccentric exercise group. Improvements in quadriceps femoris and gluteus maximus muscle volume were 23.3% (SD=14.1%) and 20.6% (SD=12.9%), respectively, in the eccentric exercise group and 13.4% (SD=10.3%) and 11.6% (SD=10.4%), respectively, in the standard rehabilitation group. Improvements in quadriceps femoris muscle strength and hopping distance also were significantly greater in the eccentric exercise group 1 year postsurgery.


CONCLUSIONS
A 12-week focused eccentric resistance training program, implemented 3 weeks after ACL-R, resulted in greater increases in quadriceps femoris and gluteus maximus muscle volume and function compared with standard rehabilitation at 1 year following ACL-R.
Gerber
J Parry
JP
US Military-Baylor University Postgraduate Sports Medicine Residency Program, US Military Academy, Keller Army Community Hospital, West Point, NY 10996, USA. John.Gerber@us.army.mil
Marcus
Robin L
RL
Dibble
Leland E
LE
Greis
Patrick E
PE
Burks
Robert T
RT
LaStayo
Paul C
PC
D000328:Adult; D016118:Anterior Cruciate Ligament / Q000503:physiopathology / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries; D002081:Buttocks; D004434:Early Ambulation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007718:Knee Injuries / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D009929:Organ Size; D052097:Quadriceps Muscle / Q000473:pathology* / Q000503:physiopathology*; D020127:Recovery of Function / Q000502:physiology; D055070:Resistance Training / Q000379:methods*; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult