From the Guidelines
The most effective physical therapy exercises for quadriceps and hamstring strengthening after anterior cruciate ligament reconstruction (ACLR) include isometric quadriceps exercises, such as static quadriceps contractions and straight leg raises, which can be safely prescribed during the first 2 postoperative weeks, as well as leg press, hamstring curls, and eccentric cycle ergometer training, which can be initiated at 3 weeks after surgery 1. These exercises are effective because they mimic functional movements while providing progressive resistance, which stimulates muscle fiber growth and improves neuromuscular coordination.
- Isometric quadriceps exercises, including static quadriceps contractions and straight leg raises, can be started during the first 2 postoperative weeks and confer advantages for faster recovery of knee range of motion without compromising stability 1.
- Leg press can be started at 3 weeks and can improve subjective knee function and functional outcomes, although it may not result in significant gains in strength at 4 months after surgery 1.
- Hamstring curls can be performed using a functional pattern similar to a half squat (0°−45°) to improve quadriceps and hamstring strength, functional activities, and subjective function, with monitoring of anterior knee pain and progression of load 1.
- Eccentric cycle ergometer training may result in greater strength gains, better daily activity level, and greater quadriceps muscle hypertrophy if initiated at 3 weeks instead of 12 weeks after surgery, with the beneficial effects persisting 1 year after ACLR 1. It is essential to start with lighter weights or body weight and gradually increase intensity as strength improves, performing these exercises 2-3 times weekly with at least one day of rest between sessions to allow for muscle recovery and growth. Key considerations for rehabilitation after ACLR include early mobilization, patellofemoral pain reduction, and the introduction of open kinetic chain exercises, which may vary depending on the graft type used 1. Neuromuscular training should also be added to strength training to optimize self-reported outcome measurements and prevent reinjuries 1. Psychological factors, such as self-efficacy, locus of control, and fear of reinjury, can influence the rehabilitation process and return to play after ACLR, and should be evaluated using an objective instrument 1.
From the Research
Quadriceps Strengthening Exercises
- The study 2 found that an eight-week quadriceps strengthening program was effective in improving pain, function, and quality of life in patients with knee osteoarthritis.
- The program consisted of quadriceps strengthening exercises, which were applied in a randomized clinical trial and showed statistically significant differences in all variables assessed.
Hamstring Strengthening Exercises
- The study 3 suggests that eccentric knee flexor conditioning reduces the risk of hamstring strain injury when compliance is adequate.
- Exercises with a proven benefit on biceps femoris long head fascicle length and improvements in eccentric knee flexor strength should form the basis of effective injury prevention protocols.
- Hip extension-oriented movements, such as those that activate the biceps femoris long head and semimembranosus, may be beneficial for targeting specific muscles in injury prevention programs.
- Knee flexion-oriented movements, which activate the semitendinosus and biceps femoris short head, may also be effective for hamstring strengthening.
Key Considerations
- When selecting exercises for hamstring strengthening, consider the impact of exercise selection on muscle activation and the effect of training interventions on hamstring muscle architecture, morphology, and function 3.
- Practitioners should consider the effect of a strength training program on known or proposed risk factors for hamstring injury 3.