Glutes are arguably the most important muscle group for runners. Unfortunately, they are also the most neglected in terms of maintenance and strength. Studies link glute weakness to achilles tendinitis, runner’s knee, iliotibial (IT) band syndrome and other common injuries.
If you glutes are so important and their weakness contributes to many injuries, why are they neglected. Simply put, most athletes of all ages are unaware of the role their glutes play in their running performance. The goal of this article is to create a better awareness of the function of glutes for runners, what causes glute weakness or imbalance, how to identify if you have a problem and how to stretch & strengthen your glutes.
Your gluteus maximus is your butt, the two smaller, glute muscles (called glutes) are located on the side of your butt, near and slightly above your hip joint. When we run, the glutes’ job is to hold our pelvis level and steady. The gluteus maximus is responsible for hip extension, or raising your leg behind your thigh and knee behind you after pushing off with your foot. Good hip extension creates the energy of that leg swing into forward motion.
The problem is, without good hip extension you won’t have a powerful stride, which means your speed will be limited. The other key role of glutes for runners is providing stability for the pelvis and knees and keep our legs, pelvis and torso aligned. If you have strong glutes, side-to-side motion will be limited and you will be a more efficient runner because your energy is directed forward. Basically you can faster at the same effort level.
Also, when the glutes aren’t working properly, some of the impact forces are transmitted elsewhere down the legs. It’s common for many runners to have strong abs and back muscles but weak glutes.
How does this Glute dysfunction occur?
It’s common for the gluteal muscles to become inhibited which will prevent them from properly engaging and being able to perform their role.
Part of the problem is that glutes aren’t as active as other running muscles during routine activities. This leads to your hamstrings, quads, and calves becoming disproportionately stronger (also called an imbalance).
This imbalance limits the effectiveness of the glutes. The end result is that if we aren’t aware of this imbalance and subsequently correct it, typical movement and habits will place increased emphasis on the stronger muscle groups such as the Quads, rather than allowing the glutes to contribute properly within the running motion.
This kind of strength imbalance can cause injury problems over time as the body learns not to use the glutes as it tries to favor the stronger quads. If not properly identified, a glute weakness/imbalance typically doesn’t get corrected on it’s own because most runners don’t perform strength training exercises that isolate and strengthen the glutes. Exercises you can complete to fix this problem are listed below.
Additionally, excessive sitting can cause tight muscles, in particular the hip flexors, which will then inhibit the glutes, making them weak and ultimately pulling your pelvis out of alignment.
Bottomline, you need to work the smaller glutes to stay injury-free. The following video helps to explain the issue.
Glute Strength Tests
To see if you have weak glutes, you’ll need to perform the following glute strength tests.
Standing Glute Test – Left
Standing Glute Test – Right
Stand with your hands over your head, palms together. Lift your right foot off the ground and balance. Watch the left side of your hips to see if it dips down. If it does, it’s a sign of glute weakness.
In these photos, I’ve inserted a YELLOW HORIZONTAL LINE, to help identify whether or not my hips are dipping. You can have a friend take a photo while performing this test or you can complete the test while in front of a mirror to observe results yourself.
I recommend the photo, so you can look at the results more closely.
Try it on the other side, too. Next, do this: While in the same position, lean to the right of your body, checking to see if your left side dips. Move your hands to the left of your body and see if your right side dips. If your hips dip, it’s a sign that your glutes need work. Try this test also after a long or hard run to see how your glutes perform when fatigued.
Glute strengthening and stretching exercises
For each exercise start with 10 reps the first week and then progress to 15 reps (switch legs), rest for 30 seconds and complete 3 total sets.
Watch this video for a modified lunge stretch using a chair:
Tight hip flexors can inhibit the firing of your glutes. Complete this stretch after every workout (crossfit/conditioning or run)
Step forward and lower your back knee. Keep your knee over your ankle. Hold for 30 seconds on each side.
Glute & Hip Strengthening Exercises
This video shows some exercises that are completed with a stretch cord. Stretch cords may be available at your gym. If you don’t have access to a stretch cord, you can complete the exercises below (see photos and descriptions).
Kick Backs – This exercise engages the middle-butt and low back.
Start on all “4s” by placing your hands under your shoulders and knees under your hips.
Extend your right knee and hip to even your right leg with your torso. Be sure your foot is flexed and your neck is neutral by looking down towards the ground. Hold momentarily. Return to starting position.
This exercise is a variation of kick backs. While your elbows and right knee are on the ground, lift your left leg until it is parallel with the ground. This is your starting position. Lift your left leg up about 6-12 inches while keeping it straight and then return to your starting position.
This exercise strengthens the gluteus medius and minimus (smaller muscles in the butt).
Start on all “4s.” Next, make a 90 degree angle with your right leg and then lift your right leg up 6-12 inches while keeping your knee bent. Hold momentarily, then return to starting position.
Lie flat on the ground with your hands by your sides and your knees bent. Pushing up mainly with your heels, keep your back straight and raise your hips up off of the floor. Hold there at the top for a few seconds and then go back to where you started and repeat. For an added bonus, try this exercise with only one foot on the ground at a time!
Single Leg Squat:
Stand on your left leg. Lift your right out in front of you. Stand tall (don’t round your shoulders), and keep your left knee over your ankle as you lower down into a squat. Your hands can extend out for balance.
Modified Single Leg Squat:
Stand on edge of curb as shown in image. Raise right leg slightly and squat slightly with left leg (note how right foot is higher in 1st photo, side view). Start with 8-10 squats/leg and after completing this exercise 3 times/week for 2 weeks, increase to 15 squats/leg.
Last year when I surveyed hundreds of runners who visit middleagemarathoner.com, to no surprise, I found that injuries were the biggest obstacle faced by middle age runners. Coach Greg McMillan is currently conducting his own survey and he shared with me that his initial results showed a similar finding.
The purpose of this article is to provide four different strategies to help you avoid injuries. These aren’t the only four strategies you should use and you may already be using a few of these strategies yourself, but hopefully I can share something new that you can try to further injury proof your body.
Background: For the longest time, I felt like I was a slave to nagging injuries. It was one of my biggest challenge that was preventing me from regularly racing 1/2 and full marathons. Being a busy professional, I simply didn’t have time to implement a comprehensive injury prevention routine. About 99%+ of the middle age runners whom I coach don’t have a lot of time either. However, it’s important for any runner to engage in some kind of program that involves some of the strategy that I discuss in this article.
Over the years, I worked with my primary physician, physical therapist, athletic trainers and running coaches in addition to completing a lot of my own research and trial/error to finally develop my own injury proofing regime. There’s not a “one size fits all” solution when it comes to middle age runners and injury avoidance.
Bottomline, I eventually “cracked the code” of injury-free running. Since 2012, I have been injury free.
Note, that I didn’t say I have been pain free. There’s a difference and it’s how you manage your pain that greatly contributes to remaining injury free. It’s remaining injury free that allows runners to build consistency and reach their goals.
Following are four of the strategies that I use in parallel to remain injury free.
1. 3 Too’s – I’ve read this from a few sources as the leading cause of running injuries.
a) Too much – mileage – depending on your base, athletic ability and running experience, running too much weekly mileage can lead to injuries.
b) Too soon – weekly increases should be limited to no more than 10% of the previous weeks’ total mileage. Increase your weekly and monthly running totals gradually.
c) Too much – change – although it’s important to vary your weekly workouts (discussed below), going from the couch to running every day and also completing heavy conditioning workouts will likely lead to injury. It’s important to gradually (over several months) increase the intensity of your training. Your body needs to be ready to increase mileage, run intervals or perform intense conditioning workouts.
2. Vary the intensity, mileage & route of your workouts. This is essential in my training plans. Changing pace, intensity and duration of runs will help ensure you improve. You can’t expect to improve if you run the same route at the same pace, day after day. Simply varying the routes or running surfaces is one of the best ways to spread out the various forces on your lower body so that no one tissue or tendon gets overworked.
3. Practice proactive recovery – along with the 3 too’s, you should regularly use a foam roller and an occasional ice bath. I use compression socks to help me recover from both hard and long runs. However, to truly be proactive, you need to complete workouts at a level where your body is ready. This means scheduling workouts based on other workouts you will or have already completed that same week or in previous weeks. Coach Jay Johnson says, “keep the hard days hard and easy days easy.” I also recommend taking at least 1 day off (no exercise) per week.
4. Listen to your body – along with being proactive you need to also be reactive with your recovery. If something you’re doing is resulting in pain that forces you to alter your running form, I strongly recommend stopping that particular activity, identifying the root cause of the pain and seeking professional medical advice to eliminate the issue. If the rigors of training for a particular race like a full or half marathon become too painful, you may need to postpone the race or simply run a shorter race like a 5 or 10k.
BONUS: 5. Use a coach – A good running coach can provide you with a training plan that meets your athletic ability, goals and helps to prevent injury. Sometimes I adjust scheduled long runs, speed work and some of the scheduled high-intensity training. This allows more time to rid yourselft of the pain and get healthy so you can get back to your training.
If you’re not doing so already, implementing these strategies will make a big difference to your performances over time. Although each strategy isn’t a “cure-all.” If after working these strategies into your plan and you still are fighting the injury bug, then I would replace one of the days you run with a cross-fit/aerobic (eliptical, stationary bike or swimming) and conditioning workout. If after making this change you still continue to get hurt, then I would visit with a medical professional and if you’re not with one already, I would speak with a coach who can take a look at your training and suggest some alternative workouts that may help you train injury free.
In this article, I will discuss how to use a foam roller and why a foam roller is my “secret weapon.” Foam rollers are great tools for both injury prevention and performance enhancement. Foam rollers are the poor man’s massage therapist. They can provide soft tissue work to help many athletes, in any setting. Sources & references that I used to help me complete this article are listed at the end of the article.
A foam roller is simply a cylindrical piece of extruded hard-celled foam. Think swimming pool noodles, but more dense and larger in diameter. They usually come in one-foot or three-foot lengths. I find the three-foot model works better, because I can roll on both legs at once, but it obviously takes up more space.
Foam Roller Basics
Foam rolling is a form of self-massage that helps to relieve muscle tightness. Rolling applies pressure to specific points on your body that helps loosen the muscles and assist in returning them to normal function. When I think of normal function, this means your muscles are elastic, healthy, and ready to perform at a moment’s notice.
However, for me, a foam roller is more than a tool to rehab injured muscles, I believe it should be used by healthy runner’s to warm-up and cool-down after workouts. Rolling properly on foam can improve circulation. Rolling breaks down knots that can limit range of motion and it can prepare muscles for stretching. Foam rollers, when used correctly, can release tension and tightness between the muscles and the fascia (which surrounds the muscle or group of muscles). Foam rolling, as well as dynamic stretching (after a run or after foam rolling) can help improve flexibility and range of movement, and actually decrease the risk of injury.
It’s important to move slowly and even stop and hold the roller on tender spots. Ensure you breathe through the discomfort. If an area really hurts, go gentle on it and support some of your weight elsewhere, using your arms. One thing you want to avoid is rolling on an injured or inflamed area of your body. For this reason, I recommend to those that I coach to go indirect before direct. This means that if you find a spot that’s particularly sensitive, ease away from that area by a few inches. Take some time to work a more localized region around areas where you feel discomfort. Work these “neighboring areas” before using larger, sweeping motions. Eventually work to keep pressure on the affected area with the foam roller. You can add more “weight” as the muscle relaxes by stacking your legs. With a foam roller, you can basically work to your own pain threshold.
I know many people that don’t want to roll, because they think it will hurt. This may be true, especially when you start rolling for the first time. There can be some discomfort, but this is often because these muscles are tight. Once loosened, rolling is rarely painful. Instead it feels very good on tired muscles.
The foam roller is a critical part of my marathon training. Just remember that your legs are “round” and not “flat.” This means that you shouldn’t roll on one side of your leg. Work all sides of your legs. Especially the IT Band (discussed below).
If you’re new to foam rolling, start out gradually with lighter pressure and a shorter session. In time you can progress to more intense pressure.
While foam rolling can be done both before and after a workout, pre-workout sessions should focus on problem areas whereas post-workout sessions can focus on all of the muscle groups worked that day.
The key to foam rolling is to use your body weight on the roller.
I’ve attached a few videos from various sources to help demonstrate how to properly use a foam roller. These are my favorite foam roller exercises:
1. Warm-Up – Use the foam roller prior to running. Complete light rolling with long, sweeping strokes to the long muscle groups like the calves, adductors, and quadriceps. Focus on areas that are particularly stiff. Be careful not to roll on your lower back. If you feel stiff, rolling increases blood flow and helps to relieve muscle tightness that can interfere with proper running form.
2. Cool-Down – Use the foam roller after running and stretching. Similar to warm-up, lightly roll with long strokes all around your legs. You can roll on your upper back because the shoulder blades and muscles protect the spine, whereas there is no similar protect if you were to roll the lower back. Concentrate rolling on areas that seem particularly stiff or sore.
3. Calves – This is the most common foam roller exercise along with hamstrings. Place the roller under one or both of your calves. If only doing one calf at a time, rest your other foot on the floor. Roll all the way from your ankle to below the knee. As discussed above, your legs are round and not flat, so rotate your legs in and then out. If you want to add pressure, simply stack your ankles.
4. Hamstrings – Along with calves, another very common rolling exercise. Place the roller under your thighs. Roll from the knees to the buttocks. To increase the pressure, roll one leg at time while turning your leg in and out.
5. Front Shins – If you are suffering from shin splints, then you should roll on the outside part of your lower leg (the part associated with shin splints). Besides biomechanical inefficiencies, the primary reason for shin splints is a muscle imbalance in your lower legs. Shin splints typically occur with beginner runners or a runner who’s returning from a lengthy layoff. When running on hard surfaces with worn out or ill-fitting shoes, the weaker front “Anterior Tibial” muscles are overloaded or shocked by the stronger calf muscles.
In this article, I want focus less on rehab and more on how to use a foam roller for the Anterior Tibial muscle. If you are suffering from shin splints, take this exercise slow to prevent further injury. Start at the top (near the knee) and work down then up again along the outside front of your leg. You can do this in a kneeling position or a position similar to a plank. However, as with most foam rolling stretches, you might need to adjust to target the muscle (and not fall over in the process).
6. Iliotibial (IT) Band – Until I successfully loosened up my IT Band with the foam roller, I experienced what felt like, never ending foot and ankle discomfort. My Doctor had confirmed that I wasn’t injured. However, it was my Physical Therapist who connected my tight IT Band as the root cause of my aches and then showed me how to properly roll on and loosen up my IT Band. After working on this for a few weeks, I noticed that the foot and ankle pain that I had experienced for 2+ years, finally went away.
To work the IT Band, lie on your side with the roller near your hip, rest your other legs foot on the floor and then move along your outer thigh. For most runners, working the IT Band with a foam roller is particularly painful. This is because the IT band is often too tight. IT Band injuries are more painful than rolling over a tight IT Band, so it’s well worth your time to perform this exercise regularly. If you don’t feel much discomfort when performing this exercise, then try increasing the pressure by stacking your legs. When you feel discomfort, go slow and let IT Band loosen itself. Don’t forget to breath while performing this exercise.
7. Quads – Because your legs are round and not flat, we must also roll on our quads. This is a simple, but slightly awkward exercise. Lie on your stomach with a roller placed under the front of your thigh and slowly roll up and down from the bottom of your hip to the top of your knee.
8. Inner Thighs or Adductors – I rarely perform this exercise, but I do know others who work their adductors to rehab groin injuries or strains. Lie on your stomach with one leg extended slightly to the side, knee bent. Place the roller in the groin area of the extended leg and roll the inner thigh. You’ll have to brace yourself with your elbows (like a plank) to complete this roll.
9. Gluteus or buttocks – your butt does a lot of work when you’re running, so you need to treat it with some foam rolling. You should also take the time to roll on your lower back. Make sure that you roll slowly. You get more benefit from the foam roller when you go slow over the tightest or most painful areas.
10. Other areas to roll – neck, hip flexors and feet
Assessing Effectiveness of your foam rolling efforts
As discussed, it can be hard to use a foam roller, especially if it’s slightly painful. Massage work and even some stretching can also be uncomfortable, especially with stiff or “knotted” muscles. Therefore, it is important that runners learn to distinguish between a moderate level of discomfort related to working a muscle’s trigger point and pain or discomfort that can lead to injury.
When you complete a foam rolling session, you should feel better, not worse. The roller should never cause bruising. The first thing you should do after foam rolling is ask yourself how your muscles feel. Once you start feeling the awesome effects of rolling, you’ll want to make it a part of your regular training regime. Remember to be patient. Becoming mobile and strong requires a long-term commitment to foam roller deep-tissue massage and other recovery work.
If you continue to feel pain after your foam rolling sessions, you should visit a physical therapist. You may have an injury or it might be possible that you’re simply not rolling correctly.
In addition to my vast experience of training with a foam roller, I used the following sources & references to assist me in completing this article on how to use a foam roller.
Peak Fitness by Mercola.com
I appreciate any comments and feedback on this article. Please follow me on Facebook and Twitter
One way to minimize risk of injury, while maximizing the life of your shoes, is to rotate use of your shoes.
I follow Peter Larson’s Runblogger.com. Although I don’t know Peter, it appears that he’s able to make a living blogging about running. His writing is insightful and well researched. The following story was recently published and makes sense.
For the last 20 years, I have run in the same shoe until it’s time to move on to a fresh pair (typically 450 – 500 miles). I have been fortunate to avoid any “major” injuries. However, because I pronate, I require a stable shoe. Also, I’m somewhat of a heal striker, so I need additional padding.
Currently I have had success with the Asics GT2000. Although this model is no longer produced, I’ve been able purchase 2 new pairs in the last 45 days (on Amazon for $75 and at a local sporting good store for $60). I’m of the opinion that if you’re able to train in a particular shoe or if you have a couple of shoes you wear (a lightweight pair for the track or trail running shoes) that allow you to train for marathons injury free, then stick with that shoe. If you can find a pair on sale, then make the purchase regardless of need. These days shoe manufacturers are so quick to upgrade a shoe and take it’s predecessor off the market so you’re forced to pay $120+.
Peter discusses rotating shoes for different workouts. Please take a look at the following post and let me know what you think.
The reality is that a segment of the running community has long recognized the value of rotating shoes for different workouts or to keep the legs fresh. However, there are more than a few runners who would never consider doing so and to whom the concept of a shoe rotation is totally new and a bit scary.
A fair number of the injured runners I see in the clinic do all of their training on roads in a single shoe (or maybe two very similar models from different brands). Often when I bring up the idea of rotating shoes the response is something along the lines of “It’s OK to do that???” Many are receptive to trying something different, but when I tell them it’s ok to mix a new shoe in with their current one on different workouts they seem perplexed.
I’ve long wondered why running shoe companies and retail stores aren’t more vocal about this concept of a shoe rotation. It seems like a win-win (provided the runner can afford multiple pairs of shoes). I’ve asked a few retailers and brand reps about this, and there seems to be some sensitivity about the possibility that a customer might feel they are being pushed to buy something they don’t need. Shoes are expensive after all, and getting more expensive every year.
I do think that the article makes good sense, and it’s written by Spencer White, head of the Saucony Lab. Spencer is a good scientist, and I’ve spent a few days with him down at Saucony HQ (he did a full gait analysis on me with their force treadmill and 3D kinematic setup). He and I share a lot of common ground in our thinking about shoes, running form, and injuries, and this paragraph pretty much sums up my own thinking on why rotating shoes makes sense:
“Our bodies are best at doing one thing: Adapting to the environment and the stresses we expose them to. For runners this means that our bodies adapt to the stress of running, becoming fit and strong. But… because running is so repetitive, it can occasionally overstress our bodies, especially when we increase training intensity. Every step loads the same tissues in the same way as the previous step. Running shoes can affect how the stress of running is distributed within the tissues of your body. By wearing different shoes on different days, you may avoid overloading any one muscle, tendon, bone, or ligament while simultaneously strengthening others.”
Spencer goes on to talk about shoes and speed:
“If you run at different speeds on different days, or on different surfaces (if you don’t do this, you should!), you may find that a shoe that feels just right at a training pace feels too mushy for intervals, or that the racing flat that works so well for a track workout just feels jarring when running more slowly on the run home. For many runners, a shoe that compresses more feels like it works better with their stride at slower paces, while a shoe that compresses less feels like it works better with their stride at faster paces.”
I personally liken running shoes to golf clubs. A golfer would never play 18 holes with just a putter. Golfers have a bag full of clubs that each has an intended purpose. In a similar manner I think some runners would benefit from having a few different shoes to use for different purposes. Find the most comfortable shoe you can find for most of your mileage. Get a flat for days you run a bit faster. A trail shoe to maximize variation by getting yourself off of the road once in awhile. I think that by mixing things up you’ll avoid hammering your body with the same repetitive stress every time you run, and this might reduce your chances of getting hurt.
What do you think, do you find value in rotating shoes?
Staying injury free with your running is critical if you want to reach your goals. If you’re injured, you can’t train and if you can’t train, you won’t run achieve your goals. My marathon training plans incorporate at a minimum, the following 5 steps. In a separate checklist, I outline in detail 8 things that you can immediately implement to ensure you remain injury free.
1. Rest or decrease your mileage every 3-4 weeks. While training for a race, you should keep track of your weekly mileage. This is especially important while gradually increasing mileage. The body needs some rest from the pounding of running to stay injury free. Every 3-4 weeks, depending how strong you are feeling, reduce your mileage for the week. I suggest reducing by 25% for intermediate runners and around 40% for beginners.
2. Remember weekly mileage. No matter how strong you are feeling, it’s not recommended to increase weekly mileage by more than 10% per week. Also, I do not think it’s wise to increase the length of the weekly long run by more than 2-3 miles each week. I’ve made this mistake before when I was training for the Portland Marathon a few years ago. Sudden mileage increases in excess of 10% each week can increase injury risk. To be able to avoid injuries while you add miles, take an additional day off every 4 weeks. It helps you complete scheduled long runs, but incorporating rest into the week will help your body heal faster.
3. Warm-up at the beginning of training runs. When you start each run or interval session with some light stretching in addition to 4-5 minute jog. You may also transition in to the faster pace with 4 short accelerations/strides. When the legs warm-up, improve your pace gradually. Doing strides and incorporating some jogging or recovery for no more than 30 seconds between sets of 2 x 100m, you will soon have the ability to hit your target pace during track workouts
4. Regularly run fast. This doesn’t mean each time you head out, go fast. Rather, you must regularly complete track and hill work. Should you only do speed work monthly, the body won’t get used to faster running. One speed workout each week will help you get faster and get in better shape, injury free. Don’t forget, whenever you do speed work, always warm-up first.
5. Staying injury free can best be accomplished by stretching right after runs. Stretching right after a run, when your muscles are warm, can help combat all the contractions you have with each and every step. Following a high exertion effort, try to avoid stretching intensely. Stretching a tired muscle an excessive amount could tear muscle tissue and basically increase the time to recover. After hard workouts I recommend that you stretch lightly.
I enjoy following Peter Larson’s RunBlogger blog. Peter has time to analyze running a little more technically or “science like” than I can and he has good insight. Over the last month, I too have been researching whether I’m a heal striker and whether I should work to correct my gait. I continually battle sore ankles and feet. My physical therapist took some video of me running on a treadmill and told me that I’m a heel striker. He recommended that I shorten my stride and try to maintain 180 steps (both right and left) per minute.
The easiest way to do this is to count your right or left steps (every time your right or left foot hits the ground) for 30 seconds. Multiple the result by 4 and this is your total steps per minute. Ideally you want to be at 45. I’ve been working on doing this for the last 2 weeks. It feels like I’m running with my shoes tied together, but I am able to run at sub 7:00/mile pace. The challenge is being able to run with these short steps without thinking about it. I think it will take me quite a while to get used to these shorter strides. When I first started counting my steps, I was closer to 160 steps/minute. Now I’m around 172 – 174. I either need to shorten my stride further or move my legs quicker.
Over the past few days I’ve been reading my way through the June 2013 issue of Footwear Science (sure to be found on a newsstand near you!). The issue is a compilation of presentation abstracts from the annual meeting of the Footwear Biomechanics Group that was recently held in Brazil. To be honest, I eat this stuff up, and this is probably the first periodical I’ll have gone through cover-to-cover in a few years. There are a ton of interesting studies in the issue (I hope to write about several of them), and one that I found particularly fascinating was titled “Initial foot contact patterns during steady state shod running.”
In the study, a group from Belgium led by Bastiaan Breine set out to examine foot strike patterns among runners using a novel measuring device. What they did was place a pressure sensing plate on top of a force plate so that both underfoot pressure tracings and force application could be recorded simultaneously.
Traditionally, foot strikes have been classified either visually (point of first contact between foot/shoe and ground) or by using a method known as the Strike Index. With the Strike Index, footstrike is classified by the location of initial contact as determined by center of pressure tracings under the foot. Using the this method, initial contact (IC) under the rear one-third of the foot would be classified as a heel strike, IC under the middle one-third would be classified as a midfoot strike, and IC under the anterior one-third would be a forefoot strike (which in my opinion is problematic since this requires a very anteriorly placed initial contact to score a forefoot strike).
The authors of this study observe that although pressure tracings might be recorded at initial contact, the actual forces at work might be very small and functionally irrelevant. So, in addition to scoring foot strikes by location of initial contact as determined by pressure tracings, they decided to also score foot strikes based on the location of maximal impact loading rate (impact loading rate is the rate of force application and is typically expressed in units of body weights/second). Max loading rate is functionally meaningful in that higher max loading rates have been linked to increased risk of injuries like stress fractures.
So what did they find? Using Strike Index only they found that 45 out of 55 runners were rearfoot strikers and the remaining 10 were midfoot strikers (same pattern on both feet). However, when they used the location of the instant of maximal loading rate to classify foot strikes they found that:
1) On the left foot, 11 of the 45 heel strikers were actually midfoot loaders, and 1 midfoot striker was a forefoot loader.
2) On the right foot, 13 of the 45 heel strikers were actually midfoot loaders, and apparently 2 heel strikers were forefoot loaders.
Below is a reproduction of their figure showing what the underfoot pressure tracings for the various strike patterns look like:
What you’ll note from the above diagram is that the blue and red tracings both originate on the rear, outer portion of the heel indicating initial heel contact. However, things differ from that point on. The blue line moves quickly forward along the outer margin of the shoe and peak impact loading rate actually occurs under the midfoot. The red line veers inward a bit and peak loading rate is squarely in the center of the heel. So, although the initial contact pattern is similar (both are “heel strikers”), the actual loading pattern is very different. The authors feel that those exhibiting a pattern like the blue line should not be considered heel strikers. If the proportions in their sample are reflective of the frequency with which these patterns might be found in the broader running population, it might mean that as many as 25-33% of “heel strikers” don’t actually load much at all under their heels!
My personal interest in this study is that I’m pretty sure that my foot strike tracing would be in the blue-line category, or somewhere between blue and green. I’m a mild heel striker if you look at me on film in most shoes, but when I was running on the force treadmill at Saucony HQ I was told by biomechanist Spencer White that I loaded under the midfoot. This would also seem to explain to me why my wear patterns nowadays originate at outside of the heel and extend forward along the lateral edge, whereas I used to absolutely destroy just the back-most corner of my heels. I suspect when I went through my running form experimentation phase a few summers ago I shifted my tracing from red to blue, and in some shoes (and barefoot) to green. I’m beginning to also wonder if this might explain why I’m so sensitive to heel-forefoot drop in running shoes – given my mild heel strike it seems to not take very much additional material under the heel to start messing with my stride. It would be very interesting to take this group of pseudo-heel strikers and examine how their stride changes with varying shoe properties.
Perhaps the biggest issue that this study might bring up is that any other studies that have compared heel strikers to midfoot or forefoot strikers may not have actually been comparing what they thought they were comparing – it really depends on how the heel strike was classified. If it was done by video or by Strike Index alone there may have been some midfoot loaders in the heel strike group…