The Lunge: Form Versus Function, Part 1: Screening

Shouldn’t the middle of the knee sit directly over the second toe during a full lunge?

This is an extremely common question asked during courses and discussions about movement screening, functional training or rehab. There may be bigger issues to discuss in fitness, but this one is still a firm favorite.

It is unclear where the concept of the knee staying over and not transgressing the second toe originated. Some claim it was first noted in a 1978 Duke University study, but based on this author's reading, research and discussions, this “old nugget” could very well be a case of unsubstantiated wisdom. The idea's proponents often claim that this position will reduce loading forces and be less injurious to the knee, especially when the femur/thigh sits horizontally and the foot is orientated inline with the femur. A 2010 study challenged this notion by taking 18 subjects through 12 rep max long step lunges and short step lunges while recording forces and EMG recruitment patterns. The researchers found insignificant ACL tension in the short lunge with greater knee flexion taking the knee past toes. They also noted significantly greater PCL forces in the long stride lunge, where the knee stays behind the toe line (Escamilla et al., 2010).

In addition to carefully positioning the knee during a lunge, many also recommend a vertical and centered spine during the exercise. The idea is that the calf, quad and hamstring groups will be less prone to stress/injury, and that the whole movement will be more “stable” if these clearly defined guidelines are strictly followed. This has also become “common knowledge,” with countless mentions within instructional articles. For example, in the article "The Anatomy of a Perfect Lunge," Dyan Quesada states, “The most common error made when performing this exercise is not keeping the back in a straight line when bending both knees" (2006).

However accepted these concepts have become, the real world continues to challenge them. If this is truly the most efficient way to perform lunges, then shouldn't this also be the most common way for athletes to perform them in "real time” athletic function? Therefore, if we observe lunge-based sports and activities, we should see that the most efficient and effective athletes employ the most efficient and effective lunge form, especially if they have also been trained by folks who are great believers in the universal knee-over-toes concept.

We would expect to see this:

But instead we find this:

What we see in free-play is the body making all sorts of angles and shapes, often at the extremes of 3-dimensional movement, but clearly still recognizable as a lunge. It is common to observe these same shapes in most other dynamic sports as well, be it hockey or fencing, or a sport with no handheld driving force, such as soccer. Put simply, the body is doing whatever it can to “get there,” and the best athletes are able to pull this off successfully. But what happened to the perfect lunge form? Now before folks jump up and start howling…yes, it is clear that these movements are being driven by extreme environmental necessity, and that the athletes are performing close to their thresholds. It is also clear that if we asked them to do this, and only this, during both their training preparation and court-play time, there would probably be dire consequences. But have no doubt, when the umpire calls play, or the referee blows the whistle, the shapes that our athletes will be striving for will look like those above. It is our job to train, maintain and rehab these athletes to a point where they can make these shapes not only safely, but also somewhat better than the next guy.

Where does the conceptual 90/90 lunge fit into all this?

You’d think nowhere, but let’s not ditch it yet. To figure out what really works, it makes sense to study a sport that requires multiple lunges—in this case, we'll look at badminton. Without a doubt, badminton players must master the lunge, be it to get to a drop shot, to defend the mid court, or to perform repetitive, but essential, practice drills on court. If anyone can display or benefit from perfect lunge mechanics, it will be a badminton player.

(Please note: Even though we'll focus on the sport of badminton in this article, the lunge-based concepts can be applied to many other sports, or we could say "sports preparation" as a whole.)

If we look a little deeper into badminton's association with the lunge, we can recognize a potential 3-tier pattern:

1st Tier - At the Gym

During the athletes' strength and conditioning sessions, the lunge is certainly popular, but its form is predominantly along aligned 90/90 criteria. Stride lunge and line lunge walks are common, and the heavy loading sessions are all wisely performed with nailed and aligned form.

2nd Tier - Technical On-Court Drills

Not surprisingly, badminton players do a lot of court drills—refining, rehearsing, and optimizing the essential shot-making skills that they will need during game play. Repetition is essential, or at least unavoidable, and in this sport it is not unusual for the coaches to set up tables full of hundreds of stacked shuttlecocks and “multi-feed” them over the net in specific hitting patterns…short to long, mid-court side-to-side saves, short and recover and short again, etc. Hundreds of lunges are performed, with the majority pretty “clean,” maybe not always 90/90, but often not far off. Skilled coaches can manipulate this by subtle pace and direction changes of their feeds, but on most occasions the athletes drop into a rhythm that allows them to arrive at these shots in some tidy and reliable shapes. And, of course, there is a reason…these drills have to be predictive, since the athlete is striving for this bio-motor rhythm and the coach has to hold them off from their end range threshold or risk a breakdown of the drill. The aims and demands of the drill dilute the "chaos factor" found in competitive free-play, and the extreme lunge shape-making is equally diluted. (Note to reader: diluted doesn’t mean “easy.”)

3rd Tier - Competitive Play

This is the unpredictable “chaos” of competition…see previous images where we covered the expansive nature of competitive lunge mechanics.

There seems to be a “leap of faith” between each of these three tiers. The use of the lunge is neither seamless or functionally progressive. If we believe that ultimate performance relies upon ultimate preparation, then there seem to be gaps. Is our training and conditioning truly supporting a high success rate with multi-dimensional threshold lunge ability, or are we leaving a fair few stones unturned?

1st Tier Screens: The Primal Lunge

The lunge has become known as one of the primal or primary patterns of movement (Chek, 2003). Think of it as a biomechanical “constant,” or an essential building block of many more complex movement sequences or chains. It is an essential component of dynamic sports and activities, a tool that can be used during the training and preparation for these activities, but it has also become a biomechanical “marker” for assessment of movement competence. Our understanding and application of movement screening is growing and almost all screening systems will include observation and interpretation of a “lunge” as part of its protocol.

The problem is, there is a lunge, and then there are lunges…

The supposedly unadulterated, standard, textbook anterior lunge will be the mainstay of most assessment protocols. Perhaps with a stick down the back, or maybe “in-line.” It’s a good choice, as we can observe front leg force absorption, lumbo-pelvic control, spinal angles, trail leg release and right/left symmetry among many other things.

This simple screen is without doubt a powerful and recommended assessment tool. Assessment techniques such as Gray Cook's Functional Movement Screen system may highlight this vertical spinal posture and provide perfectly valid, reliable comparative interpretation. If your client/athlete is struggling to control the range, stability, and timing demands of this fundamental movement, then it is clear they may have issues when they need to employ it at speed and under load and fatigue during more dynamic activities. The screening observation may give the "green light" for the trainer to intervene with corrective and progressive training protocols that help "clean up" the client’s issues with their lunge screen. But therein lies the problem…their dynamic activities will go on to ask more of this lunge, and our screening protocols should reflect this inevitability. Just because you are competent with the fundamental anterior lunge doesn’t mean you will demonstrate the same competence with the production and recovery of a frontal plane lunge, or a transverse plane one, or a lunge that incorporates opening the anterior muscular "chain."

2nd Tier Lunge Screens

Fans of the toes over the knee, please take a look at the examples above. Even though we have altered the lunge mechanics to help focus our observations, there is still a strong flavor of “alignment” to these moves. The knee is, in fact, sitting over the lead foot in the first 3 examples...the trunk stays centered and often upright, with the pelvis relatively level. So, is this the way to do it? Are they the biomechanical markers that we are looking for? It would help to consider these variations of the lunge as “2nd tier” movement screens. There is more variation and motor expansiveness than a simple anterior lunge (1st tier screen?), but the movement is still quite predictable in its nature, and competent movers will perform them in “default” mode, with the body sub-consciously taking the safest and most reliable route to get the job done—a bit like the skilled badminton athlete performing their court drills within their threshold. Of course, less competent or functionally-compromised movers will show us dysfunction.

The question arises…can we claim that we are fully understanding an athletes’ movement competence without taking our screening of the lunge into 3rd tier territory? A “level” of movement where we see the elements of chaos and sheer necessity driving the body into making more extreme shapes and moves. Of course if we decide to do this we need some form of order to this apparent chaos to ensure our screening remains reproducible, comparable and sets recognizable benchmarks. We have to concede that it is extremely difficult to test at absolute threshold, but we can find ways to get closer to it and still gather reliable results.

3rd Tier Lunge Screens

From a standing position an anterior long lunge with alternate toe touch is performed in the images below. In this case, it is also performed “in-line," narrowing the base and exposing more frontal plane demand. Note how the athlete has to:

• get through the forward leg hip and rear leg calf, decelerate and recover with the posterior chain,
• displace and control the center of gravity away from the lumbo-pelvic “safety zone” and over the lead leg,
• add a compound spinal rotation to make the reach,
• push back and out of this lunge to the standing start position in order to assess their ability to re-gird and recover from an end range lunge.

Below is another example of an anterior lunge and recover, but this time incorporates a full-range frontal plane drive. Notice how the pelvis counter displaces against the trunk dragging the knee with it outside the foot. Efficient lateral chain function decelerates and recaptures this dynamic movement…or, in the case of movement dysfunction, it will fail to do this and regional distortions, pronation and restricted range may be observed and recorded. (Frontal plane stability has been somewhat under-estimated in many athletic assessment protocols.)

Next, the lunge is now performed into the frontal plane but includes a full range and dynamic transverse plane drive. Notice how this exposes lead leg dynamics. In this case, the right leg is driven to the right and we observe it releasing into a pronation deceleration with a contra-lateral trunk rotation and a supination deceleration with the ipsilateral rotation. We should also expect to see efficient control of relative internal and external rotation at the hip.

This is an anterior in-line lunge incorporating a full range transverse plane reach backwards. It drives the trunk into extreme counter rotation if the left foot is forward and left shoulder driven back, but also tests control of the trunk and lumbo-pelvis “opening out” as the shoulder drives to the right. A big question of control and resistance (stability) is asked of the lead leg as it anchors and modulates this total body movement.

We have traveled a long way from the standard primal lunge. Without a doubt, we have also come a long way from worrying about the single criterion of whether or not a knee is sitting directly above a second toe. You will need to consider force absorption and production mechanics, chain function, core and dynamic stability, motor patterning, specific regional movement control, symmetry, and doing this in multiple planes…lots of stuff! You can seek out where your athlete’s strengths are and expose where their weaknesses lie.

In fact, an understanding of one single “movement” has almost become a basis for observing an athlete's global motor competence. READ THIS SENTENCE AGAIN.

This is a concept that could be at the hub of what we do as personal trainers. At first, it seems a bit unwise. Why restrict your assessment of a client’s expansive athletic ability to variations of one test movement? However, ALL dynamic movements are subject to ever-present “functional constants,” with many of these constants (as mentioned previously) all revolving around our ability to deal with gravity, ground reaction, momentum control, force absorption and re-girding production…and all in a balanced, 3-dimensional, reproducible and often high threshold manner. So, in fact, we could consider that we are not actually testing the “lunge,” but merely using it as a tool to test our client’s abilities with the all-important functional constants. A lack of competence with these has consequences for ALL movement, and not just the one you have chosen to test and observe. This framework of 3-tier thinking can be applied to all of the familiar test/primal movements that we commonly apply in our movement screening processes. It can be easily adapted to a squat, or a jump, a single leg dip, and to some extent to a pull or a push. The test movement can be expanded from its most primal foundation 1st tier presentation all the way up and close to its 3rd tier threshold, and most of this is done by applying the outlined framework of the 3 planes of movement and an expanding threshold of range. Once comfortable with this, you have a system that can provide you with a huge insight into an athlete’s movement competence. If necessary, this can be taken further with other components being added such as external loading, speed and repetition/fatigue.

Initially it can appear daunting though because, quite frankly, it looks like a lot of work, especially when considering we mentioned that this is just one of the fundamental movements that we could opt to screen. This does not have to be the case, and in fact we only employ 3 or 4 of these fundamental movements within popular screening systems. Humans are uniquely bi-pedal, and our functional locomotion is driven by our ability to sling one foot in front of the other, control it, recover it, and do so any which way that is needed. Understanding this most primal component of our motor capability is a prime target of movement assessment, and manipulating the way we evaluate a lunge can help us in this process.

Are you going to throw this 3-tier lunge process at every client and athlete that you work with? Not wise. Our screening systems and skills need to be adaptable. We all work with different communities and face different constraints. We absolutely need the more standardized screening systems that provide us with definitive quantitative reasoning tools, just as we also need to develop and trust our abilities to observe and interpret movement from a more qualitative perspective. Once we start to observe and discuss function in motion, we recognize distinct “rules of engagement.” These are the functional constants. They never change and they provide us with a common language to share.

What could be the way forward in applying a more expansive approach to lunge screening? Always trust and test the basic anterior lunge variations because they are a proven and reliable indicator. However, practice and, when possible, employ a frontal plane, transverse plane and posterior lunge variation and develop your observations of good benchmarks for these movements. When comfortable with this you can become more expansive and choose variations that are relevant to your athlete or that challenge the integrity of the movement patterns you are rehabilitating/training. Test, test again, observe change, evaluate progress.

At this point, we have simply examined the lunge as a movement observation tool. The second article in this series goes on to investigate what we can do with it as a training tool.

References

1. Escamilla, R.F. et al. (2010, Oct). Cruciate ligament forces between short-step and long-step forward lunge. Med Sci Sports Exerc . 42(10):1932-42.
2. Gray, G. (1995). Lower Extremity Functional Profile. Wynn Marketing.
3. Gray, G.  Functional Video Digest Series.
4. Chek, P. (2003). Primal Pattern Movements. Chek Institute.
5. Clark, M. (2003). Essentials of Integrated Training.
6. Cook, G. (2003). Athletic Body in Balance. Human Kinetics: Champaign, IL.
7. Kritz, M. et al. (2009). Using the body weight forward lunge to screen an athletes lunge pattern. NSCA.
8. Page, P. (2002). The Janda Approach. Thera-Band Academy.
9. Quesada, D. (2006). The Anatomy of a Perfect Lunge. Get to the Core, Inc. Retrieved from http://www.coretherapy.com/health_news/articles_the_anatomy_of_%20a_perfect_lunge.html.