Quick Hit Summary
Hamstring strains are one of the most frustrating injuries for athletes to suffer. It seems that once a hamstring is injured, it’s likely to be injured again within a couple of years. In a recent study, it was shown that even when pain-free, previously strained hamstrings lack strength/power during eccentric muscular contractions. In addition there range of motion is limited during hip flexion. In order to combat this problem, I recommend including more Single Leg Romanian Dead Lifts (SLRDL) into your exercise program.
Hamstring Strains
How many individuals have injured their hamstrings while training? Furthermore, how many have injured the same hamstring multiple times to the point where you now seem to have chronic hamstring problems? I’m sure that many hands would go up if I asked this question to group of seasoned athletes, especially those who play sports requiring high velocity movements. It seems like once you have hamstring problems, you always have hamstring problems.
Figure 1 Muscles of the hamstrings. From top to bottom: semimembranous, semitendinosus and biceps femoris (long head). The short head of the biceps femoris is not highlighted in any of these pictures.234
Recently a research study was published that may be of importance to those suffering from chronic hamstring strains. What did it say? Read on to find out!
Research on Chronic Hamstring Strains
In a recently published paper, researchers examined the biomechanics 26 males who were fully recovered (ie- could exercise pain free) from previous hamstring strains. For reference, each athlete had on average 2 hamstring strains within the past year. Additionally, the average degree of severity was a grade 2 strain. For reference, a grade 2 strain is one in which you walk with a noticeable limp, have pain upon touch, but not so severe that it has detached from the bone. Lee et al. looked at the performance of their injured leg vs. their non-injured leg while they were running at 80% max speed or while performing resistance based exercises1. The researchers were particularly focused on the eccentric strength and power of the previously injured hamstring vs. that of the normal leg as its generally under these types of contractions where strains occur.
As hypothesized, during the resistance portion of the testing, it was found that the eccentric strength and power of the previously injured hamstring was compromised (vs. non-injured leg). During the running portion of the testing, results indicated that hip flexion of their injured leg was significantly less (2º) than that of the uninjured leg.
Interpreting the Research
Unless properly strengthened (see below), hamstrings are at a higher risk of reinjury as they’re put into a stretched position. Since each degree of hip flexion puts the hamstrings on greater stretch, the body may try to prevent reinjury by subconsciously decreasing hip flexion.
The runners in this study were only going at 80% max speed. Differences in hip flexion may be even more drastic when going at 100% intensity. Two potential problems occur with reduced hip flexion. First, it increases the risk of injury as the body attempts alters its mechanics to account for the difference. Second, from a performance standpoint, with reduced hip flexion comes slower speed (don’t misinterpret this statement to mean that you should be pulling your knees to your chest while running!!!). In conclusion, this study shows that weakness in the eccentric strength/power/flexibility of an injured hamstring may be the underlying reason as to why reinjury commonly occurs.
Exercise to Help Prevent Reinjuring the Hamstring
Please Note – This article is only focused on the hamstring muscle itself. If you find that you have chronic hamstring strains, the other thing to consider is if your hip flexors are tight which causes your pelvis to tilt anterior (ie – forward), putting additional strain on the hamstring and nerves that innervate it. Based off the work of Janda, this would mean the key is strengthening the hamstrings while stretching the hip flexors to allow for better pelvic alignment.
One of the single best exercises that I know of to prevent hamstring strains, as well retrain those which already have been injured, is the Single Leg Romanian Deadlift (SLRD). Rather than explain every detail of the exercise, I have a URL link that shows a demonstration of the exercise. Please note, that I have no association with the individual demonstrating the exercise. I found it simply through searching on google and was the first decent demonstration of the exercise that I came across:
This exercise fits perfectly with the research gathered by Lee et al. As you can see, this exercises both the eccentric and concentric functions of the hamstring. This is similar to running where the hamstrings are continuously cycling between eccentric (swing phase) and concentric actions (pull through phase). Additionally the hamstring is stretched through a full range of motion to help account for the loss of flexibility commonly seen with this type of injury.
There are a few quick notes that I’d like to make that were not explicitly mentioned on this video:
On the swing leg (leg not in contact w/ floor)
First, one may work work towards being able to keep both legs next to each other while performing the lift or minimize backward swing with leg. This is the form championed by Ian King when performing the lift. However, I've had trouble with individuals first starting this lift to perform it correctly in this stance due to the increased difficulty of it. Thus I've went to building to this position as an individual gets more comfortable with the hip motion (ie – start off with leg swing and build towards both legs together). I will start out by allowing the swing leg to go back with body other while the other one is firmly planted on the ground. One should be able to keep a straight line through their body, extending from the top of the head—>butt—>heel.
- Have athlete consciously contract his/her glutes (butt) muscles as if they were trying to crack a walnut between them.
- Have athlete straighten out their swing leg as if they were trying to touch their heel to the wall behind them.
- Tap the athlete’s glute muscles to helps facilitate their contraction. Be sure to ask the athlete/lifter for permission first.
Second, keep your toes pulled towards your shin (ankle is in a dorsiflexed position) on swing leg throughout entire movement. Often athletes/lifters will point their toes towards the wall behind them (plantarflex). I want them to them dorsiflexed to strengthen the anterior muscles of the lower leg.
Third, make sure the athlete DOES NOT OPEN UP THEIR HIPS. If you look at the video, you’ll notice that the guy’s hips are always “square” to the floor. They are not rotated to one side or another. Often when first mastering this lift, athletes will allow their hips to “open up” to the side of their swing leg. Here are some coaching cues to help with this prolem:
- Have athlete engage their core muscles prior to lowering body and make sure their belly button points straight at the ground.
- Additionally, tell them to point the toes of their swing leg directly into the floor or towards the heel of their stance leg.
- If all else fails, hold their hips square to the ground throughout the movement. to help them acquire correct kinesthetic awareness of movement.
- As athlete gets more comfortable, have them bring swing leg back in line with stance leg depending on the goal of what you're trying to accomplish.
Now as you get this move mastered w/ the swing leg going behind you, work towards keeping the swing leg "still", by the side of your other leg for even greater challenge.
On the stance leg (leg in contact w/ floor):
First, the knee can bend with the movement. It doesn’t have to be in a locked position. However, the majority of the movement should come from your hips. Try to lower your body by pushing your butt towards the wall behind you. When you can’t push it any farther behind you, pause and then return to the starting position. If you try to lower yourself further, you’re probably going to round your back.
Second, the guy in the video talks about “pushing through your heel” when returning from the bottom. Rather than think about that, I want athletes to return to the start/vertical position by consciously contracting their glute muscle on their stance leg. In other words “pull through your hips” in order to return to the start position. Although there will be some hamstring contraction, I want most of the pulling motion to come primarily from the glutes. The more active/stronger your glute muscles, the less likely you’ll have hamstring problems. Again the "squeeze your butt like you're trying to crack a walnut b/w the cheeks" has been a useful cue. (As a side note – I learned that one from a high school athlete I was working with as he was "coaching up" one of his teammates.)
Another general problem is that athletes like to look at themselves in the mirror as they’re performing this exercise. In most circumstances, I think its beneficial to use a mirror while learning an exercise. That way you can visually see what you’re doing which often helps. However, I’ve found that athletes tend to lose there balance while looking at themselves in the mirror while lowering their body. This is caused from bending your neck to see yourself, putting your head position (w/respect to your neck) in an unnatural position. Think of it like this, when walking, do you ever bend your neck upward toward the ceiling/sky (which would put your neck in the same position as you’d be if you were trying to lower yourself while looking at a mirror)? Of course not!
As a final tip, this is the one exercise that I generally allow individuals to use some light weight when starting vs. using just body weight. Instead of boring you with the biomechanics of it, I’ll just let you know that it will help athletes maintain balance. I recommend holding 5-10 lbs in the arm opposite of your stance leg (ie-left leg on ground, weight in right hand). Having the weight in your opposite arm will also help keep the hips from opening up as well.
Bottom Line
Hamstring injuries are common to many athletes who compete in anaerobic based sports. It seems like once one is injured, it always stays injured. A key exercise to help hamstring strains is the Single Leg Romanian Dead Lift (SLRDL). Incorporating this exercise into your routine will strengthen the hamstring at it’s most vulnerable points, thus, reducing your risk of injury.
Stay healthy and Good Luck!
References
1 Lee MJ, Reid SL, Elliott BC, Lloyd DG. Running Biomechanics and Lower Limb Strength Associated with Prior Hamstring Injury. Med Sci Sports Exerc. 2009 Sep pg. 1942-1951.
2 Accessed May 30, 2010 from: http://en.wikipedia.org/wiki/Semitendinosus
3 Accessed May 30, 2010 from: http://en.wikipedia.org/wiki/Semimembranous
4 Accessed May 30, 2010 from: http://en.wikipedia.org/wiki/Biceps_femoris
5 Article archive photo. Created by Chuck Marean. Accessed June 19, 2010 from: http://commons.wikimedia.org/wiki/File:Hamstring_stretch.jpg