Athletes recovering from an injury typically follow a progression through the rehabilitation process ultimately leading to return to play. Functional testing algorithms have been proposed to ensure that every athlete is tested along the continuum of rehabilitation to address each physical quality of performance (8). For the strength and conditioning as well as the rehabilitation professional, restoration of strength and power is paramount to a successful outcome and optimal performance. Several studies have demonstrated that power differentiates elite from nonelite athletes in the same sport (3,4,6,10,15,19,20). Therefore, integration of power-based exercises should be the focus of the terminal phases of rehabilitation as the athlete transitions back to the weight room. Without a proper strength base, however, optimal power cannot be achieved.
Athletes recovering from injury, particularly in the lower extremities, have specific considerations that need to be addressed in rehabilitation. For example, Neitzel et al. have shown that athletes recovering from anterior cruciate ligament (ACL) reconstruction “unconsciously unload” their involved limb up to a year after surgery (14). In other words, athletes do not realize that during bilateral lower limb tasks, they are shifting weight to the uninvolved limb. Furthermore, Paterno et al. (17) and Chmielewski (7) found that athletes unload their involved limb up to a year after surgery during performance of a depth jump. Another study found avoidance of high vertical impact forces and compensation during bilateral movements in 50 ACL-reconstructed patients (5). Finally, a study by Angelozzi et al. (1) found that it took a year after surgery before the rate of force development in the involved limb was equal to the uninvolved one. From these studies, it is evident that unilateral deficits present after lower extremity injuries exist and need to be a focus of rehabilitation and strength and conditioning. Without appropriate loading of the involved limb, an athlete will struggle to change direction properly, may leave the uninvolved limb at risk of overuse injury, or may cause reinjury of the involved limb when the athlete eventually must fully load it during athletic competition.
“Triple extension” is a combination of ankle plantarflexion, knee extension, and hip extension. It is the synergy of these 3 individual components that allows an athlete to run, jump, sprint, and change direction to perform their sport movement. Deficits in ankle plantarflexion have been found after Achilles tendon reconstruction (12) and knee extension after ACL reconstruction (23). Therefore, it is plausible that deficits along the kinetic chain will have a detrimental effect on power through triple extension. Depending on an athlete's individual impairments and functional limitations, components of triple extension are addressed in rehabilitation, but rarely together. For example, a common step-up exercise involves hip and knee extension but lacks ankle plantarflexion. Another example is the heel/calf raise exercise. With this exercise, the athlete commonly has the hips and knees already extended while they perform ankle plantarflexion. It is well documented that, particularly after an injury or surgery, the athlete may demonstrate deficits in neuromuscular coordination (9,13,16,18,24). The lack of neuromuscular control may lead to several deleterious effects including aberrant movement patterns that can exacerbate the current injury or potentially cause a new injury. Furthermore, deficits in neuromuscular control may cause inefficient movement through improper mechanics of sport activities. Intuitively therefore, these movements can and should be addressed in earlier phases of rehabilitation to eventually help maximize return to sport activities such as running, jumping, and cutting.
Triple extension is maximized most by the use of Olympic-style movements such as the clean, jerk, and snatch (2,11,21). Although the recovering athlete may not be appropriate for high loading and/or complex movements like these in the early and middle phases of the rehabilitation process, the movements can be facilitated in a safe manner. The following are suggested interventions to facilitate power development and triple extension in the terminal phases of rehabilitation.
See Video 1, Supplemental Digital Content 1, https://links.lww.com/SCJ/A166.
Because of unloading of the involved limb during double-leg tasks found in previous studies, it is common for the recovering athlete to struggle with performing squats correctly. Under the skilled eye of a rehabilitation or a strength and conditioning professional, tilting of the pelvis or side flexion of the lumbar spine can be observed in an athlete who is not symmetrically distributing weight. Therefore, the rehabilitation or strength and conditioning professional can facilitate weight shifting to the involved side by putting the uninvolved limb on a small step. Once the athlete can squat with proper form, the step can be removed. Ultimately, this exercise helps ensure that the athlete is ready for more complex movements like back/front squats and Olympic-style lifts.
TRIPLE EXTENSION HEEL RAISE
See Video 2, Supplemental Digital Content 1, https://links.lww.com/SCJ/A167.
Here, the athlete triple flexes, then triple extends. The subject is shown barefoot in the video only to illustrate even distribution of weight among the metatarsal heads during the activity. Shoes are encouraged during performance of the exercise. The athlete may have their hands on the wall for either safety or to help ensure proper performance of the exercise. Any athlete who lands from a jump or decelerates before changing direction needs to triple flex before triple extending (23). Common errors in performance include frontal plane tilting of the pelvis, “hiking” the hip to compensate for weak hip extension, inability to maintain ankle dorsiflexion at the start of the movement, and inability to fully extend the hip, knee, and ankle.
TRIPLE EXTENSION LUNGE
See Video 3, Supplemental Digital Content 1, https://links.lww.com/SCJ/A168.
The athlete completes a walking lunge, then plantarflexes the ankle after the concentric hip and knee extension. Common errors with this movement include lack of frontal plane control of the pelvis and knee, lack of transverse plane control of the knee, or loss of balance in the triple extension position. Additionally, the lunge can be modified based on the subject's diagnosis. For example, an athlete with patellofemoral pathology can perform less knee flexion and more hip flexion (knee behind the toes) to reduce patellofemoral compressive forces. However, when trying to facilitate a more quadriceps-dominant lunge, more knee flexion (knee over the toes) may be performed.
TRIPLE EXTENSION STEP-UP
See Video 4, Supplemental Digital Content 1, https://links.lww.com/SCJ/A169.
The athlete performs a step-up, but adds ankle plantarflexion to the movement. Dumbbells or barbells can be used for resistance. The rehabilitation or strength and conditioning professional should be mindful of the athlete being able to maintain proper balance during this movement.
See Video 5, Supplemental Digital Content 1, https://links.lww.com/SCJ/A170.
Weyand has previously stated that the most explosive athletes put the most amount of force into the ground and spend the least amount of time on the ground (22). Here, the athlete “punches” the step to elevate the amount of force. Although this is not a triple extension movement, it encourages single limb force. This punch into the ground is similar to the bilateral tasks involved in Olympic-style lifts.
Before adding these modifications into a program, the athlete should demonstrate proficiency with the more “standard” heel raise, lunge, and step-up. Furthermore, the athlete should be able to maintain the fully extended position without a loss of knee extension, hip extension, or maintenance of erect trunk posture. Adding these modifications is a simple way to “begin with the end in mind” and facilitate athletic movements before the athlete returns to more complex movements in the weight room and ultimately, back to sport.
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