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ACL Injury: Returning from Rehab Back to the Gym

In this article, we will review contributing factors, the anatomy of the anterior cruciate ligament, knee biomechanics, stages of rehabilitation and safe program design for working with a client who has sustained this specific injury.


Learning objectives:

  1. Identify the cause of anterior cruciate ligament tear
  2. Understand the Medical/PT management of ACL repair
  3. Identify the physical therapy/stages of rehabilitation
  4. Identify, which exercises, are safe vs. unsafe based on biomechanics and science
  5. Design a Program for an ACL repair client understanding the science and evidenced based research


ACL Injuries are one of the most prevalent knee injuries that affect females 3-9x more likely to being sustained then men. Resulting in at least 200,000 ACL repair each year with an est. cost of $3 billion (Frobell, R, et al 2010). According to the research, there are several factors that predispose women to ACL injuries.

Predisposing Factors


Research has shown that the women have weaker glute medius and glute minimus (Willy, R, 2013 & Jacobs 2007). Also, per the research female athletes have a combination of decreased relative hamstrings and high relative quadriceps strength or a low hamstring (H:Q) strength, place them at an increased risk for ACL injury.


Women biomechanically recruit their quadriceps more than males in order to stabilize the knee joint during sport specific movement.  When transitioning from jumping to landing, it has been shown, that women tend to demonstrate more valgus deformity, which is due to poor landing mechanics and weaker lateral stabilizers as per the research.


Female athletes tend to increase quadriceps activation during plyometric (Ford KR et al. 2011).Women also tend to demonstrate more knee valgus during side step cutting using more vastus lateralis muscle than men do(Ford 2005).  Women also overly contract their quadriceps muscles when decelerating to a ball as seen in soccer, whereas men use more hamstring activation (Ebben, W, et al, 2010).

Anterior Cruciate Ligament ACL Injury

The Mechanism of injury of an ACL injury is where an athlete or person is struck forcing tibia on femur, hyperextending the knee. This creates immediate swelling, inability to straighten knee, and pain with walking.


The classic symptoms of an ACL injury are that the individual presents with local swelling with loss of 10 degrees of knee extension.

Rehab: our goal is to reduce swelling, improve and restore extension first then strengthen vastus medialis oblique muscle.

Phases of Rehabilitation

Phase 1:  (0-4 weeks)

Goal is to improve mobility then stability. Gaining full extension of knee with strengthening using static exercises (body weight)against gravity, such as straight leg raises.

Phase 2: (4-8 weeks)

Goal is to improve knee mobility, followed with hamstring, glute and static core strengthening.

Phase 3:  (8-12 weeks)

Goal is to improve dynamic stability in the knee and hip junction. Followed with dynamic strengthening of lower extremities. Exercises such as in place lunges, forward and diagonal reverse lunges are taught to the patient during this phase.

Phase 4: (12-16 weeks)

  • 3 ½ months light jogging begins
  • 4 months running begins
  • 4 months introduction of plyometrics
  • Surgical reconstruction typically sidelines athlete for 6-9 months and once cleared by M.D. can return to sport activity

Program design for ACL client

Working with an ACL client requires careful thinking and planning with respect to one’s program design. It is important for clients with history of an anterior cruciate ligament injury/repair when transitioning from physical therapy back to the gym or exercising at home, that it be done carefully. The focus of the training should be on continued strengthening the hamstring, glute maximus, glute medius, and glute minimus muscles.

Biomechanically, the strengthening of hamstrings pulls posterior(back), taking pressure off the ACL. The stabilizers of  the hip(glute medius and minimus) muscles need to be stronger as they are involved with functional activities such as getting in and out of car, out of bed or  with athletes, cutting movements seen in sports such as soccer and football.

Program design should be based on science not guessing. Program design should be personal and customized with the focus on return to sport vs. functional strength.

Unsafe exercises

There are several exercises that a client with an ACL injury should avoid. First, biomechanically during seated leg extension machine, this exercise creates the greatest  amount of shearing force of the tibia on the femur. When performed from 30 degrees of knee flexion to knee extension.

Second, pistol squats cause increased compression force and pressure to the patellofemoral joint. Finally, depth jumps are another exercise that I would highly recommend to not teach your clients. This exercise biomechanically places a tremendous amount of compression and loading to the ACL region, which is unsafe.

Post Therapy Focus

Simplifying things. When working with an ACL client, the focus of post therapy should  focus on:

  • Stretching quadriceps, hip flexors, ITB and HS
  • Focus on strengthening hamstrings
  • Dynamic core strengthening
  • Dynamic balance training


Knee injuries plague all individuals from the average person to the athletic population. One of the most common injuries affecting women more frequently than men for the past several years per the research, are anterior cruciate ligament sprain/tear injuries. Now understanding the contributing factors, the anatomy of the anterior cruciate ligament, knee biomechanics, stages of rehabilitation and program design, should prepare you to work with any ACL client.

written by Chris Gellert, PT, MMusc & Sportsphysio, MPT, CSCS, C-IASTM, CPC

Chris is the CEO of Pinnacle Training & Consulting Systems(PTCS). A continuing education company that provides educational material in the forms of evidenced based home study courses, ELearning courses, live seminars, DVDs, webinars, articles and teaching in-depth, the foundation science, functional assessments and practical application behind Human Movement. Chris is both a dynamic physical therapist with 19 years experience, and a personal trainer with 20 years experience, with advanced training, has created 16 home study courses, is an experienced international fitness presenter, writes for various websites and international publications, consults and teaches seminars on human movement.