Why tight hamstrings matter part 2

In Part 1 we looked at the function and physiology of tight muscles and how progressive lengthening and strengthening can improve your rehabilitation and performance. Part two of this series looks at the bio-mechanical implications of tight hamstrings.

The mighty Hip Hinge

This action is arguably the most important movement for a healthy low back but also for force production through your hips. To simplify: hinging at the hip is what should happen when you bend forward at the waist. In an ideal movement your torso maintains a neutral (picture 2) posture while almost all of the forward bend occurs around your hip axes. A poorly performed forward bent shows limited change in the hip angle with excessive bending through the low back. hip-hinge

 

Poor movement or posture in this forward bend excessively loads your spine and intervertebral discs. It also destroys any mechanical advantage meaning our muscles have to fire harder when we bend forward and return to standing. Think through how many times in the run of a day would you bend forward and return to standing. Imagine you work in a plant or factory where you spend the majority of your day leaning forward over an assembly line or work table. How long before this excessive loading starts to wear on the joints and tissues of your back.

Back to hamstrings. They are one of the strongest limiters for this hip hinge. In a proper hip hinge you take your hamstrings through considerable lengthening. If you lack flexbility in your hamstrings you will quick stop pivoting about your hips because your hamstrings have pulled tight. If your haven’t reached the end of your required movement then you will likely bend through your spine to make up the difference.

Spine stability while running

Imagine yourself on a bosu ball, a balance board, a floating wharf on a pond. Every time the platform tilts forward you adjust your posture. Wobbling side to side makes you constantly lean side to side to stay upright. Your spine is undergoing the exact same balancing act as you run. Every foot strike tilts your pelvis side to side and the muscles around your spine work hard to keep your spine and torso balanced above.
So here is the important question, does your back hurt after you run. If yes is your answer maybe it’s time to think about spine stability while you run.

The sideways hip drop

Since your spine and pelvis operate in 3 dimensions let’s simplify things and just worry about side to side movements. What is unique about running versus walking or even standing is that you’re jumping from one leg to the other. When you walk you have near constant support on both feet, especially during that all important foot strike where forces going through your body are the greatest (*somewhere around 1.5 – 2x your body weight). During running one foot hits the ground while the opposite leg is no longer supporting that side of your pelvis. So what happens? You have one force driving upwards through the support leg and 1/2 of your body weight driving downwards on the unsupported side. That’s somewhere in the realm of 2-2.5x your body weight forcing your pelvis to tilt in the time it takes your foot to fully hit on the ground, milliseconds. In that same time your spine has to quickly react, help absorb that force and keep your torso upright. You’ll repeat this process about 4000 times in a 5K run.
running-hip-arrows

 

Making the correction

Having the strength to absorb that force is paramount. That strength comes from a group of muscles called your hip abduction complex which includes well known muscles like your glutes (maximus, medius and their youngest sibling minimus) and other less common muscles like piriformis, superior and inferior gemellus. These muscles help lift your leg to the side if your not standing on that leg otherwise it helps keep your pelvis level. What are some effective exercises? I have three favorites for lateral hip strength and all you need is a resistance band.

1. Side lying leg lifts: Lying flat on your side with your legs stretched straight lift your leg 12-18 inches in the air and slowly bring your feet back together. Really focus on keeping your pelvis anchored by not allowing it to roll backwards or to hike towards your ribs. Wrap a light resistance band around your thighs to add resistance. You should be able to comfortably perform 5-10 repetitions. As you improve you can add 2-3 more sets of 5-10 repetitions with a 30 second break.

2. Side lying clams: It’s the exact same set up as exercise #1 but now you bend your legs about half way. Instead of lifting your whole leg pinch your heels together and just lift your knee. This exercise will really make your pelvis roll backwards so work hard to anchor your pelvis so all of the movement happens down in your hip joint not up in your back. Use the same sets and reps as #1.

3. Sideways band walks: Take a resistance band and tie it in a loop around your feet so there’s a little tension if your feet are shoulder width apart. Making sure to lift your feet with every step. Lift your left foot and step sideways to a wide stance. Then lift your right foot and slowly return to shoulder width stance. You should feel the resistance from the band with each step. If you have space repeat those wide steps 3-5 times to the left and then back 3-5 times to the right. Keep a light bend in your knees and proper back posture.

 

The forward tilt

The next dimension we want to check in on is front to back motion for your spine. The most common in this case in what is called the anterior tilt of your pelvis. It is normal to have a slight (about 10 degrees) anterior pelvic tilt. That angle allows for a normal inward curve in your lumbar spine and sets up the muscles of your pelvis and low back for the best possible strength. It’s a very common issue for runners, especially as they fatigue, to start exaggerating that anterior tilt. Now instead of having a slight inward curve of your spine it’s significant. That wharf on the pond is slanted well forward and you’re leaning back hard to keep from falling in. That alone can be exhausting and painful for your low back.

Sadly, that’s just the start. That change in pelvic and spine angle takes away from the stability provided by your abs (aka core) so you’re forced to rely on your hip flexors and long low back muscles to stabilize that poorly positioned spine. To make matters worse that altered pelvic angle makes it more to effectively use your glutes to properly absorb the force of every foot strike. Instead those forces are transmitted straight to your low back where joints and muscles a fraction the size of your hip joints and muscles are expected to absorb the same forces.side-on-runner

 

Making the correction

This can be as much about comfort and habit as it is about strength. Maybe it feels normal to increase the tilt of your pelvis so it may not be a strength issue as much as a matter of practicing good posture. Watch a couple episodes of Family Matters and carefully watch Steve Urkel, he takes posterior pelvic tilt to a very high level. If watching him helps you can work on sitting, standing and eventually walking with slightly “Urkelled” hips. You never need to take this to the extreme but just a light push in that direction. If watching some classic 90s television doesn’t solve it here is a simple drill to help you feel the pelvic position.

Sit on a fairly hard chair or bench where you can plant your feet firmly on the ground. Focus and feel exactly what part of your bum is hitting the seat. On a hard seat your should feel that pressure land right on your sit bones (ischial tuberosities to be exact). Practice tilting your pelvis forward and backwards trying to feel the pressure on your sit bones move forward and backward. Now try to isolate just moving the pressure backwards without slouching your torso. Feel exactly what you’re contract/pushing to make that movement happen. Once you’re successful there move on to standing with bent knees and try to recreate the same pelvic tilt. Progress this to walking while tilting and finally practice this technique while running.

Do you plank? This is another great way to test your pelvic control. A lot of people with low back pain feel planks working their low back rather than their stomach. This is typically because their ‘strong’ position comes from hyper-extending their low back while stabilizing with their hip flexors and low back muscles (as we talked through above) rather than their abs (aka core). To correct this position drop to your knees while staying in the plank position on your forearms. This should make it simpler to start moving your pelvis towards that Urkel position and removing the pressure from your low back. With practice you’ll be able to hold a kneeling plank with tension in your stomach and minimal pressure through your low back. The next step is key. To make this exercise more challenging dig your toes into the ground while in your kneeling plank and slowly lift your knees 1 inch off the ground. This should really ramp up the tension in your stomach while allowing you to maintain good pelvic position. Work to build your endurance in this position by holding as long as you can (up to 60 seconds) without losing posture or feeling that strain return to your low back. It’s more effective to perform the exercise for a shorter period and rest than to push through back technique or pain.

Why tight hamstrings matter Part 1

Understanding muscle physiology and biomechanics can make a world of difference to a person training but also to their recovery when injured. These concepts apply to any muscles but with the prevalence of hamstring strains being one of the highest this might hit home with more people. Since they’re fairly large ideas we’ll start with my favorite concept the length tension relationship.

Length Tension curve

This should ring a bell with anyone who has studied exercise physiology. The concept explain how and why a muscle can produce different amounts of force as it progresses from long to short and short to long. Your fingers can be a great example of how the many small fibers of any muscle interact; a key foundation of the concept. Interlock your fingers (like the photos below) and imaging thousands of tiny hooks on the fingers of one hand that will connect with thousands of hooks on the other hand. The greater the area of contact between fingers then greater the number of hooks that connect and give you the greatest strength. This follows a simple pattern: as you slide your fingers together the area of contact increases to a peak (middle image) then slowly decreases as your fingers overlap too far and slide behind your hand (third image). The curve below shows how that area of contact directly affects that muscle’s strength. I’ve added dotted lines to show the area of overlap, notice how that area of overlap directly relates to the strength curve below.

length-tension-fingers

So now apply that concept to your hamstrings but this time we’ll run the concept in reverse order, short to long. Imagine lying flat on your back and think about the length of your hamstrings. In that position they are pretty short. Probably close to that fully shortened position from the pictures above (on the right). Now imagine one leg being lifted straight in the air until your foot is directly above your hips. As your leg moved from the floor to straight up in the air it passed from near fully shortened (too much muscle fiber overlap), through mid length (optimal overlap and max strength) to near full length (minimal fiber overlap and weakness). The key is that you are not equally strong at all lengths. You have the best strength and lowest likelihood of injury in that middle 50% of the movement.

length-tension-SLR

So here is the real magic. Hopefully this turns a light bulb on. Let’s get back to tight hamstrings. If yours are tight you have probably realized that you can’t actually lift your foot all the way above your hips. If you could you’d have a fairly large range of that motion where you are acceptably strong (highlighted in green). Instead, inflexible one, you have a very narrow window (shown on the right image in green) where you are usefully strong surrounded by two equally large ranges where you are weak and susceptible to injury.

Improving your length and strength

When you get right down to performance or recovery you want a larger range of motion through which you have useful strength. Adding length to a muscle through rigorous stretching will give you greater range but all you’ve really done is spaced out those hooks. You’ll also introduced new ranges of motion that your nervous system hasn’t experienced so you can expect to be fairly uncoordinated. Proper improvements come from slowly increasing the length of a muscle while performing strengthening exercises that progressively challenge that new range of motion. This will encourage your muscle to build more hooks and train your nervous system to control this new found range.

There's nothing wrong with your…

A phrase used regularly by many health professionals and generally rejected by patients with a problem. There’s nothing wrong with your back, neck, shoulder, knee etc. Chances are if you’re in their office you know that something is wrong. My advice on this one after hearing countless patients tell me their own “There’s nothing wrong” stories or similar “It’s in your head” tales is to keep in mind who is telling you that there is nothing wrong.

Everyone will examine you through their own professional lens. Here’s an example: let’s say you have low back pain and your family doctor has sent you to specialists for opinions and treatment options.

First it’s off to a surgeon, they examine you and determine your back pain doesn’t warrant surgery. Your back pain doesn’t require removing bone, cutting tissue or reshaping cartilage so from a surgeon’s perspective there’s nothing wrong with your back.

So now it’s on for some x-rays. The radiologist looks at your x-rays and she doesn’t see any fractures, dislocations or deformities so as far as she can report there is nothing wrong with your back.

You talk to a urologist they check your urine and bladder, the nephrologist looks at your kidneys and the enterologist checks on your digestive tract. None of them see your low back pain because through their respective professional lenses. Your back pain doesn’t show up because it doesn’t fit into their expertise or expectations.

If you’ve been through this I have an important translation for you: “There’s nothing wrong” really means “I can’t find your problem” or “I can’t treat your problem”.

Understanding this very important translation should help you realize that you are ultimately responsible for your own health and you may need to take the extra step to find the right health practitioner who can find and treat your problem.