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A Knee Up to Play

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Casey walks slowly to the edge of the pool, scars from his three knee surgeries visible on his legs. Within moments, the 6-foot 5-inch, 265-pound linebacker is running in the water. His personal fitness trainer (PFT) adjusts the water depth and gradually progresses the impact to prepare Casey for a safe and comfortable return to gravity-based activity. The athlete practices specific sports-play-related drills that lessen stress on his body; the water’s natural resistance serves as adequate overload. The PFT works as a member of the recovery team, which includes Casey’s physical therapist and physician, to provide a balanced solution to simultaneous demands: on the one hand, protection against undue stress, so that the body can heal; on the other hand, enough stress to minimize muscle atrophy (Paulos, Wnorowski & Beck 1991).

PFTs who work with athletes (or weekend athletes) may be confronted with sport-specific knee injuries like Casey’s. At some point following surgery (if that’s necessary), clients will want to get back in the game. After medical clearance, and with communication from a physical therapist, they may still not be ready for the turf; but what about the surf? Water training can be just the program design element needed to bridge the gap. A PFT who understands common sport-specific knee injuries and knows how water is an ally in postrehabilitation can create a progressive workout schedule that meets the needs of clients, as laid out by their allied healthcare teams.

Sport-Specific Knee Conditions

Participation in soccer, football, basketball, skiing or tennis often generates knee injuries from a combination of cutting, jumping, twisting and stop-and-go movements. Some of the more common knee injuries associated with sports are discussed below (this is not an exclusive list). A client who has any of these conditions must obtain medical clearance before starting an exercise program.

Anterior Cruciate Ligament Injuries

The anterior cruciate ligament (ACL) plays an important role in knee stability by preventing the tibia from sliding forward on the femur. Injury to the ACL most frequently occurs when cutting (changing direction) or coming down from a jump with a straight knee. Frequently, the meniscus (knee cartilage) also tears with a complete ACL tear. The primary goal of care is to prevent the knee from giving way. ACL injuries often bring sudden pain, knee instability, rapid swelling and limited movement. But in some cases, symptoms can take as long as 6–12 hours to occur.

Recurrent episodes lead to increased wear and tear on the knee and, ultimately, arthritis. Activities that put the knee at high risk for giving way are those in which the knee is kept nearly straight. High-risk activities include cutting; jumping; and walking on uneven ground or down a slope, a hill or a flight of stairs (Torrey 1996).

Complete ACL rupture can sometimes be managed without surgery by avoiding high-risk activities, strengthening the lower extremity and wearing a custom knee brace during all activities. The brace prevents the knee from straightening completely and stabilizes the knee joint. Reconstructive surgery is recommended for individuals who cannot or do not want to give up high-risk activities associated with the knee giving way. During reconstructive surgery, an ACL graft is inserted into the tibia and femur. Today, successful knee stabilization occurs in 90% of ACL reconstructive surgeries. However, stress or load on the graft (especially in straight-knee positions) can lead to irreversible stretching of the graft and knee instability.

Posterior Cruciate Ligament Injuries

The posterior cruciate ligament (PCL) is injured much less frequently than the ACL. PCL injuries are frequently caused by a direct blow to the front of the knee. Damage to other ligaments surrounding the knee may occur in conjunction with a PCL tear. Most PCL tears that occur without injury to other ligaments can be rehabilitated without surgery. Complete rupture of the PCL alters the normal joint mechanics and increases stress on the knee joint, which can lead to premature arthritis. Reconstructive surgery may be necessary if arthritic changes are present or if the injury is combined with other ligament or meniscal injuries. Following a complete PCL tear, clients should wear a custom-fit brace for activities that include cutting, pivoting and jumping.

Meniscal Tear/Surgery

Each knee contains two menisci, one on the medial side and one on the lateral side of the joint. The menisci, which are made of cartilage, provide shock absorption and lend stability to the knee. They are most susceptible to injury when a rotary force occurs during knee flexion or extension (Torrey 1996). A torn meniscus usually requires arthroscopic surgery. Meniscal injuries can sometimes be repaired; however, it is frequently necessary to remove the damaged area. A torn or removed meniscus can lead to arthritis.

The same kind of traumas that cause sprains can tear menisci. Repeated squatting or kneeling can also weaken menisci, increasing the risk of injury. Swelling may happen immediately or within 24 hours. Other symptoms include continual pain and a clicking or locking with knee movement. Once the menisci are torn, the knee may buckle or lock without warning. Wearing a brace during activity can help protect the knee from further injury, but surgery may be needed to remove pieces of torn menisci.

Chronic Anterior Knee Pain

Chronic anterior knee pain is a general term used to describe a number of conditions that can affect the front of the knee. These dysfunctions are usually a result of overuse or poor training, but they can also be influenced by muscle strength imbalances; muscle tightness; or problems related to the anatomic alignment of the femur, tibia or patella. The various conditions that cause pain and dysfunction in the anterior knee are also collectively called patellofemoral syndrome. These are some of the conditions that may be involved:

Patellar tendonitis—a strain with resulting inflammation of the patellar tendon, usually resulting from ballistic or repetitive activities (i.e., running or jumping) or from resisted open-kinetic-chain knee extension exercises.

Patellar malalignment—poor patella positioning, which can result from imbalances in muscle strength, muscle tightness (i.e., tensor fasciae latae), variances in femur anatomy, or the size or resting position of the patella. All these factors can lead to problems with the patella’s ability to glide smoothly and can potentially cause abnormal tracking or dislocation.

Chondromalacia—softening of the undersurface of the kneecap, which results from increased wear and tear on the patella.

Osgood-Schlatter Disease—inflammation where the patellar tendon attaches at the tibial tubercle. This condition is seen in adolescents and occurs when strength demands from the quadriceps and patellar tendon pull too hard on the tibial growth plate.

Any clients with anterior knee pain should avoid deep squats and ballistic resisted knee extension. Step work can also increase anterior knee pain. Clients should be able to tolerate static squats (progressed from mini squats to half squats) of gradually increasing duration as well as straight-leg kicks.

Training in the Water

Water’s natural resistance and buoyancy create a unique training environment that makes it possible to progressively adjust muscular overload and impact. Understanding how water training differs from land training enables PFTs to optimize use of the pool environment for safe, comfortable and effective programming. Within the continuum of care (postrehabilitation, recovery and return to play/fitness), water broadens the options available to clients for comfortably progressing activity.

  • Access to a rehabilitation pool is not mandatory. A swimming pool is normally fine, since clients remain warm by staying active (suggested water temperature is 83–88 degrees Fahrenheit, 28–31 degrees Celsius). Important considerations include a safe entry and exit and appropriate water depth for training.
  • Following surgery or wound healing, an aquatic environment may be ideal during all phases of ACL rehabilitation, especially given the concerns over providing an ideal weight-bearing load (Brindle, Nyland & Johnson 2001). By training in varying depths and employing flotation and resistive devices, clients can safely progress from range-of-motion and neuromuscular-recovery activities to more aggressive muscle strength and endurance challenges and sport-specific functional movement patterns (hopping and jumping).
  • By using water as a liquid resistance device, trainers can apply functional overload through normal planes of play or through movements that mimic activities of daily living (ADL), leading to improvements in neuromuscular adaptations (Lawton & Coberly 2000; Prins & Cutner 1999). Water also provides accommodating resistance. The harder or faster clients push, the greater the resistance, which can improve power. Small modifications in speed create significant changes in overload. Clients can increase or decrease intensity on demand, simply by changing movement speed (Sanders 2000).
  • Because of water’s buoyancy and resistance, clients can expend a high volume of energy with minimal lower-body impact (Becker & Cole 1997). Running in shallow water (without a buoyancy belt) at maximal effort is ranked as one of the top 10 hardest activities, burning an estimated 17 kilocalories per minute (McArdle, Katch & Katch 1999). Range of motion at the lower extremity may be more comfortable in the water, especially for an affected limb, and strength training can begin sooner.
  • Water enables clients to perform exercises with appropriate impact, engaging resistance in the planes of weakness for healing. For example, someone recovering from a shoulder injury may experience pain on land during exercises involving shoulder flexion. When the shoulders are submerged, buoyancy assists with shoulder flexion. As a result, pain is reduced, and the client can maximize shoulder function.
  • Deep water provides zero impact, which is especially effective for cardiovascular training when there is low tolerance
    to impact. However, specificity of training for return to
    gravity-based movement (and improved land performance) is limited; therefore, a progression from zero impact to
    gravity-based movement is needed. This progression would begin in deep water, then shift to transitional or neck depth, and end in shallow water, where the impact is more similar to what occurs on land.

Partnership in the Continuum of Care

By working as team members with allied healthcare professionals, PFTs are better equipped to provide best practices for clients’ health. Certain tools help trainers bridge the rehabilitation phases that are supervised by a physical therapist. Communication between physical therapist, PFT and client is necessary to move a client progressively through the continuum of care (illness to health and fitness). Pre-exercise screening, repeated during the postrehabilitation phase, helps ensure the client’s readiness for each bout of activity and alerts the PFT to changes in condition. Being able to identify abnormal responses to exercise helps determine the appropriate next step. PFTs should look for the following:

  • a moderate increase in pain symptoms
  • moderate or greater pain during or after exercise
  • swelling
  • loss of range of motion
  • loss of function
  • increased difficulty with land activities such as stair climbing, moving from sitting to standing, and squats
  • an increase in local temperature at the knee

Appropriate actions when abnormal responses occur may include the following:

  • ice and rest
  • adjusting water depth (going deeper), to decrease weight bearing or to work in deep water only
  • performing lower-extremity exercises in straight planes
  • simplifying exercises
  • reducing size and/or speed of movement
  • avoiding end of range (Watch that water currents do not push the limb past the end of the knee’s range of motion.)
  • possibly eliminating eccentric knee extension activities, such as squats, rebounding (jumping) and step work

PFTs should refer a client to a physician if there is a persistent increase in pain and swelling, loss of movement due to pain, an abnormal gait or a limp.

There is no recipe approach for a “one-size-fits-all” training method. Each person requires individualized assessment, exercise design and supervision. When clients are ready to return to normal sports activity, the skills they’ve learned during postrehabilitation should help reduce the risk of re-injury.

Screening Guidelines

PFTs should address the following items with each client before the client begins exercising. During the program, it’s vital to be on the lookout for abnormal responses (see above) to exercise and to return frequently to these screening components to check that the client is ready to continue training.


  • Obtain medical clearance, and check for cardiovascular risk factors using the guidelines suggested by the American College of Sports Medicine (ACSM 2006).
  • Check for pain-free range of motion compared with the other knee. Have the client sit in a chair to perform knee extension with the good leg and then repeat with the affected limb. Check range of motion on both sides.

A visual analogue scale (VAS) is a useful tool for evaluating pain (Crossley et al. 2004). Ask the client to rate pain on the VAS from 0 to 10, with 0 being no pain and 10 being intense pain. If the client’s pain increases 2–3 points, decrease the exercise intensity and duration until the pain rating decreases. If it does not lessen, then refer the client back to a physician.

  • Start training a minimum of 12–16 weeks postsurgery (depending on wound healing).
  • Be sure there is no more than minimal swelling. If a client’s knee swells for more than 48 hours or the swelling produces intense pain not easily treated with normal over-the-counter pain medication, refer the client to a physician.

One of the most serious, but not common, causes of swelling is infection, which can delay the postrehabilitation process. If you believe a client may have an infection, call immediately for medical treatment.

Meniscal Tear

  • Obtain medical clearance, and check for cardiovascular risk factors (refer to ACL and PCL screening guidelines).
  • Ask the client if the meniscus has been repaired or removed. The answer will affect the postrehabilitation plan. The program can become aggressive sooner if the meniscus has been removed, especially if the focus is on strengthening the quadriceps. If the meniscus has been repaired, the client will first need to work with a physical therapist to achieve three early postoperative rehabilitation goals: getting the knee out fully straight, decreasing swelling and regaining quadriceps muscle control.
  • Check for pain-free range of motion compared with the other leg (refer to ACL and PCL guidelines).
  • Start training a minimum of 2–4 weeks after surgery.
  • Make sure the wound is healed.

Chronic Anterior Pain

  • Obtain medical clearance, and check for cardiovascular risk factors (refer to ACL and PCL guidelines).
  • Check for full knee range of motion compared with the other leg (refer to ACL and PCL guidelines).
  • Check for pain during squats, sit-to-stand or stair climbing. Conduct a simple 30-second sit-to-stand test to assess pain (Sanders 2000).
  • Be sure there is no more than minimal swelling (refer to ACL and PCL guidelines).

    Training Objectives

ACL, PCL and Meniscal Tear/Surgery

  • Stretch the tensor fasciae latae, quadriceps, gastrocnemius, hamstrings, gluteals and soleus.
  • Strengthen all muscle groups of the knee, hip, lower leg, trunk and general upper extremity.
  • Include general cardio conditioning (deep-water jogging or shallow-water walking).

A client with a PCL injury is not an appropriate candidate for pool exercise until 12–16 weeks postsurgery, owing to guidelines restricting active hamstring contraction (knee flexion) for 3 months.

The 6- to 10-week postsurgery period is the weakest point in the graph for ACL clients (Pavlik et al. 2006). Progress gradually and check for proper biomechanics and abnormal responses after each session.

Training Tips:

  • Use functional exercises to decrease stress on the knee. (Co-contraction of the quadriceps and hamstrings decreases anterior translation of the tibia. Hamstring strengthening promotes knee stability.)
  • Note that the client may wear a knee brace in the pool, especially if moves include cutting, jumping, pivoting or stepping down.
  • Avoid the breast stroke; rotary-type kicks with quick snapping movements; quick stopping or ballistic knee movements, such as jumping or rebounding, in very shallow water; and high-speed pushing off the pool wall.
  • Minimize quick changes in direction for 6–8 months; minimize complicated choreography.
  • Include balance, coordination and proprioception training.
  • Gradually increase movement size and/or speed to adjust resistance overload.
  • Work to end of range during warm-water static stretches only.
  • Use gradual progressions for squats and step work, beginning with mini squats in water that off-loads the body comfortably and then gradually progressing to shallower water.
  • For PCL exercise, minimize resisted, open-kinetic-chain knee flexion exercises (such as kicking backward into knee flexion).

Chronic Anterior Pain

  • Focus strengthening exercises on the quadriceps (especially the vastus medialis during the last 30 degrees of knee extension), trunk, gluteals and hamstrings.
  • Stretch the tensor fasciae latae, gluteals, quadriceps, hamstrings, gastrocnemius and soleus.
  • Include cardio conditioning.

Training Tips:

  • As necessary, perform cardio activity in deep water with reduced loading, gradually increasing impact by moving to shallow water as tolerated. Progress deep-water activities from straight-knee kicking (flutter, scissors kicks) to bent-knee kicking.
  • Start kicking activities with knee in extension, and progress gradually to knee flexion.
  • Gradually progress kicking to include (in the final phases of training) flutter kicking in the vertical position and then prone or supine.
  • Minimize deep squats and ballistic resisted knee extension.
  • Be aware that step work can increase anterior knee pain. Check frequently with the client and watch facial responses.
  • Check for pain during and after exercise.
  • Progress all exercises gradually.
  • Minimize rebound movements and avoid ankle buoyancy cuffs.

Bridging to Land

Clients recovering from a knee injury can’t stay in the water indefinitely. Constantly observing for signs and symptoms of pain and swelling will provide information about the appropriateness of the exercise intensity, frequency and duration as athletes move from water to land. Casey, the athlete in the opening example, bridged from water to terra firma by cross-training on land. Eventually he’d use water as an adjunct cross-training environment to supplement his land workouts. Each intervention is different, depending on the athlete. Therefore, PFTs need good communication skills so they can evaluate comfort, functional ADL skills and sports play performance in order to find the right balance between water and land sessions. Simple assessments, such as checking for swelling, may offer insights about what volume of water or land training is appropriate during the transition period.

As a PFT yourself, and a member of a healthcare team, you should always work within your scope of best practice. With proper knowledge and experience, you can offer individualized exercises that serve to extend training after “graduation” from rehabilitation. When you use water as a safe and effective gateway to land-based activities, you garner skills that enhance your expertise as a member of the recovery team. By linking clients from postrehabilitation to normal activities of living, you improve movement efficiency for sports activity and speed athletes’ return to play.




Clinical results show that athletes who participate in water rehabilitation and postrehabilitation have better scores on postural sway, indicating better balance and fewer episodes of re-injury after return to play (Lawton & Coberly 2000). Research supports using the water environment in knee postrehabilitation training programs. What follows is a review of other relevant research.

  • Twenty patients with intra-articular anterior cruciate ligament (ACL) reconstructions were randomly assigned to a land or water exercise group. Researchers recorded thigh girth, joint effusion and passive range of motion at the knee every 2 weeks for the first 8 weeks after surgery. Results indicated greater gain in peak torque during land exercises; however, the water exercise group reported greater functional improvements, along with minimized joint effusion (Tovin et al. 1994).
  • Water treadmill–trained patients who had undergone ACL reconstruction gained greater muscle girth at the calf and thigh, greater quadriceps strength and better range of motion at the knee than patients who performed conventional treadmill exercise or cycling on land (Napoletan, Janes & Hicks 1991).
  • A case study reported by Roi et al. (2005) illustrated that a 35-year-old world-class soccer player who sustained a complete ACL tear during the competitive season was able to return to play within 90 days of surgery. Sessions included a combination of aquatic therapy and land-based flexibility, strength and field work. The water- and land-based progressive rehabilitation program allowed the patient to play for 20 minutes during a game 77 days after surgery and to play a full game 90 days after surgery, with no further treatment for his knee. A personalized progressive program of water- and land-based training led to an optimal and early return to play.

Suggested Water Exercise Progressions

To ensure safety and proper exercise performance in the water, remember these fundamental skills and principles:

  • Sculling, preferably with webbed gloves at the surface, supports balance and helps stabilize the body during exercise. Check for proper vertical body alignment (begin with core stabilization) to minimize the floating effects of buoyancy, which may push the body into a horizontal position.
  • Use rating of perceived exertion to monitor intensity.
  • Water temperature combined with water pressure and turbulence may blunt pain sensations. Encourage clients to progress water exercise gradually and check for any postexercise response when they return to land. An increase in pain after exercise indicates a need to decrease intensity during the next session.
  • Gradual increases in speed or the addition of water turbulence from jets or from traveling through the water will significantly increase intensity. Encourage clients to adjust intensity by adjusting speed and effort.







    Visual Analogue Scale (VAS)Worst
    possible painNo pain


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