Jan 29, 2015Opening the Gait
If you know what to look for, watching someone run can reveal subtle flaws and inefficiencies that decrease speed and increase injury risk. This author has helped countless athletes identify and correct them.
By Dr. Karl Fields
Karl Fields, MD, is Director of the Sports Medicine Fellowship at Moses Cone Hospital in Greensboro, N.C., and a professor of Family Medicine and Sports Medicine at the University of North Carolina. He can be reached at: [email protected].
My experience with gait analysis began as a college runner at Yale University. Our coach, Robert Giegengack, had worked with the 1964 U.S. Olympic track and field team and was a keen student of running patterns. He regularly made minor adjustments to our running form, and occasionally he made major changes. For example, I tended to turn my toes outward, so he gave me drills in which I’d repeatedly run down the lines of the track until I could consistently hit the line with my big toe, even with my eyes closed. Running became easier and my competition times dropped almost immediately.
Coach Giegengack taught us the most essential lesson of running mechanics: You maximize efficiency when the body has no extraneous or wasted movement. The feet strike along an absolutely straight line, the body allows trunk rotation to the midline but not past it, the head and trunk posture remain upright with minimal motion, and the entire body appears to float effortlessly down the track.
Many factors play a role in an athlete’s gait, and as I learned firsthand, correcting a fault or inefficiency can lead to major performance gains. But to make such improvements, you must first understand how to properly analyze gait, identify any problems, and determine whether they should be corrected. Only then can you plan an intervention strategy that produces maximum results.
WHY GAIT MATTERS
Researchers who study gait can list several reasons why this area of biomechanics is important. Besides improving efficiency and performance, proper gait reduces the risk of chronic injury (by eliminating overstress to joints, bones, and muscles) and acute injury (by decreasing the likelihood of falling). Ideal gait can also hasten rehabilitation from injury, particularly any injury to the lower extremities.
The challenge, however, is that gait patterns are as individualized as fingerprints. It’s not simply a matter of pinpointing one “best gait” for all athletes and then teaching it through drills–optimal gait varies from person to person based on several anatomical and neurological factors.
For instance, most individuals are primary heel strikers, which means their heel hits the ground first during normal running. However, a significant minority are either midfoot strikers or forefoot strikers, and usually, an athlete’s natural striking pattern is what works best for them. Attempts to drastically change running form using a “one size fits all” approach typically fail, since they ignore this natural variety.
But certain gait characteristics hinder athletic performance and should be corrected. For example, wind resistance typically accounts for roughly seven to 12 percent of energy expenditure in running, and when the body rotates correctly, the thinnest profile strikes the wind and resistance is minimized. Excess rotation also forces the body to waste energy to correct head sway, trunk lean, and movement from side to side. Almost all athletes with improper rotation patterns can benefit from correction in this area.
Why is there no universal best gait? One important reason is that the same gait variance can be caused by vastly different conditions. A slight leg length disparity might make someone’s trunk lean toward the shorter side, but that same leaning can also be caused by osteoarthritis of the hip, which prohibits normal internal hip rotation on the forward leg swing. Furthermore, a trunk weakness or scoliosis might cause an almost identical leaning pattern.
Athletes consciously and subconsciously adjust their movement patterns as the body tries to maximize efficiency, avoid pain, and compensate for any weaknesses in the kinetic chain. When the mechanics they develop contain faults that hinder their performance or increase their risk of injury, careful analysis and targeted intervention are needed.
POINTS OF OBSERVATION
Over the past 30 years as a physician and researcher, I have tried to determine how best to approach gait optimization in athletes. One of the first and most critical elements of this process is effective observation, which ensures I get the information I need to decide what changes must be made.
I ask the athlete to begin with a walking gait, transitioning gradually from an easy pace to a faster one. I watch the individual walk and/or run away from me and toward me, and also observe them from the side. To ensure I gather a complete picture, I use these key points of analysis during observation:
Head movement. Is there excess vertical motion, or does the head sway from side to side?
Arm swing. Is it symmetrical? Do the hands swing forward and cross the midline of the body? Does one arm sway less or not move smoothly?
Trunk position. Is there too much forward or backward lean? Is there sway from side to side?
Pelvic rotation and position. Does the pelvis remain level as the individual walks? Does one side fail to fully rotate forward as the leg swings?
Degree of hip flexion. Is there adequate flexion for normal stride length?
Knee motion. Do both knees flex to the same level? Does the patella move smoothly and glide in its groove, or is there abnormal horizontal motion?
Overall leg alignment. Are there abnormal varus or valgus shifts in the position of the leg at any level?
Foot strike. Is it primarily at the heel, midfoot, or toe? Is there pronation, and if so, does it begin at the heel, midfoot, or forefoot? Is there supination, and if so, is it accompanied by a very loud heel strike, which suggests an overly rigid foot? Is the transition phase from foot strike to toe lift smooth, and is the pattern the same on each side?
An important caveat when following these steps is that walking gait and running gait are completely different patterns. There is much less variability in walking gait from one person to the next, particularly in terms of foot strike. While individuals may “toe in” or “toe out” and pronate or supinate, almost all will demonstrate heel strike. Since running and walking are fundamentally different activities, gait analysis for each requires its own interpretation of the function of the kinetic chain.
As we walk, we always land with the impact of approximately half of our body weight, thus creating much different stresses than running, which is essentially a series of bounds in which the full body weight is propelled forward one leg at a time. In addition, walking is a side-by-side activity during which one foot is always in contact with the ground.
A great way to evaluate walking pattern is to watch someone walk down a level beach. The footprints will be side by side, and it’s easy to see whether the feet land in a symmetrical position. If one foot rotates outward, this will clearly be shown by the impressions on the sand. The depth of the footprint reveals whether the individual is pushing with more force on one side than the other. Relative stride length, which can be determined by comparing the distance between two right imprints and two left imprints, may suggest weakness in one limb.
Running gait analysis requires a different approach. The phases of the running motion include initial foot strike, transition (forward propulsion by the leg that’s in contact with the ground), push off, and float, and then the pattern repeats with the opposite leg.
There are a few special challenges to analyzing running gait, and first among them is the amount of space needed for a runner to achieve a full, normal gait pattern. We’ve used long hallways at my clinic for analysis, but to get a more complete picture of an athlete’s running gait, it’s usually best to go outside, where you can view them from multiple angles and they can cover more ground.
Using a treadmill to analyze running gait might seem like a sensible alternative–it requires less space, and the observer can control viewing angle and distance from the runner with ease. However, relying only on treadmill-based analysis can be problematic. Runners often react differently to a moving surface underfoot than to solid ground, and their posture, leg drive, and other aspects of gait may change as a result. Some runners are also less comfortable on treadmills, and may alter their movement patterns accordingly.
While the observation points I’ve described are all important for running gait, a few key factors must be scrutinized in greater detail. First is a general impression of overall form–whether the athlete appears smooth, free-flowing, and floating as they run. This is somewhat subjective, but if you’ve ever watched elite runners who seem to glide down a track or course, you know what it looks like. At minimum, the athlete should display symmetry in form with no abnormal halting or jerking motion.
As you closely observe the basic elements of running form, you may notice certain faults. Below is a breakdown of common flaws, along with their primary causes. Movement screens, strength tests, and other types of individualized assessment are usually necessary to find the exact source of a gait problem and decide on a corrective strategy.
Head position. If you observe vertical motion, look for overstriding or weak core muscles around the pelvis. If there is horizontal sway, look for leg length disparity, scoliosis, poor lower-leg alignment, arthritis of the cervical spine, or upper-back muscle spasms. If you see forward leaning, look for postural problems, arthritis, or cervical disc injury.
Arm swing. Forward arm swing across the midline of the body often indicates that an athlete is compensating for abnormal pelvic rotation, scoliosis, leg length disparity, or generalized poor alignment.
Trunk position. Forward lean is a common symptom of chronic lower-back pain, lumbar disc disease, or sacroiliac joint problems. Backward lean is very unusual in athletes during running.
Pelvic rotation. Asymmetry in this area is often caused by a fixed sacroiliac joint. In athletes with significant leg length differences, the longer leg will often cross over the midline on the terminal swing phase and on impact, which causes excess forward rotation of the pelvis on the longer side. Osteoarthritis of the hip can also affect the degree of rotation, causing a limitation on the affected side.
Hip flexion. Ilio-psoas muscle contracture, osteoarthritis, a labral tear, a sports hernia, osteitis pubis, or any of the other common causes of groin pain will affect hip flexion, typically by resulting in less flexion on the affected side.
Knee motion. Horizontal tracking is often seen in athletes suffering from iliotibial band syndrome. An S-shaped or Z-shaped patellar motion pattern occurs with patellofemoral syndrome, and especially in cases of patellar subluxation. Genu valgum (knock-knees) is associated with meniscus problems, osteoarthritis, and abnormal femoral rotation. Genu varum (bow-leggedness) is often seen with cavus feet and in athletes with patellofemoral syndrome, plantar fasciitis, or tibial stress fractures. Genu recurvatum (knee hyperextension) is associated with patellofemoral syndrome.
Leg alignment. Poor overall leg alignment can point to femoral anteversion, tibial torsion, or anteriorly rotated hip articulations.
Foot strike. This is among the most critical aspects of gait analysis because the moment of impact is a high-risk time for injury. As described earlier, there is natural variation in foot strike, and trying to change an athlete’s striking pattern is generally not advisable. However, each type of strike has its own characteristics and heightened injury risk factors. A forefoot striker is most likely to suffer from metatarsal arch breakdown, hallux rigidus (limited big toe flexion), and hammertoes. Midfoot strikers often have resting pronation and a collapsible longitudinal arch. Heel strikers often have wider heels and significant callusing on the heels, caused by impact stress.
Pronation. Depending on the severity and whether it begins at the heel, midfoot, or forefoot, pronation while standing or walking may correct itself naturally during running, usually because the athlete develops exceptional posterior tibialis muscle strength. Excessive pronation can be detected on the leg backswing if the heel swings outward, or if the athlete shows tibial torsion or genu valgum. Those with serious forefoot pronation will often develop bunions and bunionettes.
INTERVENTION WITH ORTHOTICS
Correcting specific faults and inefficiencies in walking or running gait is a highly individualized process, requiring knowledge of the athlete’s movement problems as well as their anatomy, injury history, and athletic demands. One of the most effective intervention methods for improving gait is the use of foot orthotics. For more than two decades in my clinic, we have successfully produced orthotics to address a wide variety of conditions.
There isn’t a great deal of peer-reviewed research on the value of orthotics, but this may have less to do with their effectiveness and more to do with the logistics of designing studies. Individuals cannot be blinded to having an orthotic placed into their shoes, and thus it is difficult (if not impossible) to test a specific product against a placebo group–unlike with pharmaceutical testing, for instance, in which test subjects can be given a pill without knowing whether it contains actual medicine.
Benno Nigg, PhD, Director of the Human Performance Laboratory at the University of Calgary and a leading scientist in orthotics research, has found that the benefits of these devices come from two main sources: changing patterns of muscle firing, which reduces muscle fatigue, and correcting anatomical problems, such as leg length differences or a specific degree of pronation or supination. Consistent with the findings of this research, I have observed that only full-length and cushioned orthotics, as opposed to more rigid products, offer true benefit for most of the athletes I treat. Many athletes under my care have found relief from pain and gait-related movement problems with help from orthotic devices.
A podiatrist, team physician, or someone else with training in foot care can best determine how an orthotic should be used to address an athlete’s specific condition. But in my years of experience, I’ve developed a few general rules and observations that can help the process along:
• Individuals with rigid cavus feet or particularly high arches have shown more benefit from orthotics than any other group.
• Runners who pronate enough to visibly affect their form usually benefit from an appropriate corrective orthotic.
• Athletes with a history of stress fracture in the high tibia or above are especially likely to benefit from the extra cushioning offered by an orthotic, since these injuries are associated with high-impact foot strikes.
• Approximately three-fourths of my patients with plantar fasciitis have reported good to excellent relief of symptoms after using an orthotic.
• Individuals with “first ray insufficiency,” a condition in which the first metatarsal is much shorter than the second, often have progressive foot breakdown from excessive dynamic pronation. This condition in particular responds well to an orthotic containing a first ray post.
• A leg length disparity that results in a pelvic position shift (which can cause gait problems) generally requires orthotic correction to balance stresses in the lower extremities and pelvic girdle.
• Athletes with bunions typically have enough gait dysfunction to benefit from orthotics, but there is currently not enough evidence to determine whether orthotics can delay or prevent bunions from progressing or developing.
• Individuals who have had bunion surgery almost always need an orthotic after their procedure to prevent the bunion from recurring.
• Athletes with primary metatarsalgia (pain in the metatarsal region) can often be treated with off-the-shelf orthotics with the simple addition of a metatarsal pad.
• Athletes with a leg length disparity or foot breakdown who have never used orthotics may find that if they begin running longer distances, such as marathons, an orthotic can help them better tolerate the extra mileage.
• Orthotics are a reasonable therapy choice for athletes with recurrent or unresolved running injuries for which other treatments have failed. In many cases, orthotic use has led to a positive outcome even when we’ve been unable to understand how exactly they helped.
With or without orthotic intervention, gait analysis is a key to successful treatment of running injuries. In fact, I’ve found that analyzing a runner’s gait offers as much information as a standard physical examination. If I observe gait abnormalities that may have contributed to an injury, correction may come from an orthotic device, specific form-training strategies, or a specialized rehabilitation program.
If an athlete returning from a running injury has developed an abnormal gait, fixing the altered pattern before it becomes ingrained is crucial for preventing re-injury. For example, almost all runners who develop piriformis syndrome will return from injury with a gait in which the toes point outward on the affected side. This is caused by tightness and contracture of the piriformis muscle, which is a hip rotator. Until the athlete performs adequate stretching and rehab exercises to return the piriformis to its normal flexibility and function, their gait will remain abnormal.
For me, clinical gait analysis is a fun part of evaluating running performance. Each observation I make must be confirmed through a physical examination, and in that way I’m working almost like a detective, searching for subtle clues during the running motion and then identifying their cause and figuring out exactly what they mean. When I’m successful, the results of my search include enhanced prevention of and recovery from injuries, greater athlete comfort, and improved performance in any sport where running is an integral activity.