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The Dynasty Doctor

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Editor’s Note: We’ve received messages for years asking for coverage of medical issues facing the NFL and fantasy football owners.  ”The Dynasty Doctor” is a series we run on an as needed basis.  If you have any questions in regards to concussions, ACL procedures, recovery times from specific injuries or anything else related to medical science, submit your question here and it may be featured in an upcoming article with our own resident M.D., Dr. Scott Peak. He’s a board certified neurologist, neuro-oncologist and is the Director of Neuro-Oncology in the Department of Neuroscience/Neurosurgery for a large health care system.

After the latest installment of the Dynasty Doctor, we were asked about Miles Austin and his history of hamstring injuries.

Hamstrings are muscles that start at the hip and femur (upper leg), and insert onto the tibia and fibula (lower leg). Hamstrings consist of the semimembranosus, semitendinosis, and biceps femoris (long and short heads) muscles, all coming together to form one large muscle in the posterior thigh. The most frequently injured hamstring muscle is the biceps femoris, and we will discuss this shortly. Hamstrings are responsible for both flexing the knee joint, preventing excessive extension of the knee joint (straightening of the lower leg), and extends the hip (makes the upper leg bend downward).

Hamstring strains are common injuries in sports activities, and specifically amongst NFL players (see Table 1). An excellent study of NFL players with hamstring injuries, over a ten year period of time, showed an average of 180 hamstring strains in 144 players per year.1 213 games were lost amongst those players, with injuries described as mild in 40%, moderate in 41% and severe in 18%.1 Most injuries occurred in the preseason (53%), and over 80% did not involve contact.1 Most injuries occurred during passing plays and on special teams. The most common positions injured are wide receivers and defensive backs. Rate of re-injury was 16.5% in this study, and has been described to be as high as 34%.1

Hamstring strains most commonly occur during maximal running or sprints. In a full-on sprint, the hamstrings serve a multi-dimensional role. As a player accelerates, the hamstrings will flex the lower leg to generate forward force. At full speed, the quadriceps pull the lower leg up, and the leg is nearly straight (fully extended). As the leg starts to reach the limits of extension, the hamstrings will contract, opposing the force generated by the quadriceps muscle, slowing down extension of the lower leg, thereby preventing excessive extension (eccentric force). At the same time, the hamstrings will also pull on the hip, extending the hip (downward force on upper leg), and this is called concentric force (shortening of muscles, like doing a curl with free-weights, biceps shorten as weight is pulled towards the chest). Hamstrings are most commonly injured when eccentric force transitions to concentric force, as the hamstring is maximally lengthened, and individual muscle units are vulnerable to excessive lengthening beyond their capacity, and yet it must simultaneously shorten to pull the hip downward.

Once a hamstring strain has occurred, the underlying pathology involves bleeding within the muscle, swelling and pain. In the acute phase of injury, it is critical to treat it in the proper manner, or blood can harden, forming a clot (hematoma) in the muscle, this will eventually calcify, and that is like having a rock in muscle. Once a blood clot has calcified, it can remain present for a long time, replacing previously needed muscle fibers. In addition, scarring and connective tissue can replace muscle fibers, reducing the number of muscle fibers present, and this results in shortening of the hamstring muscles, reduction in flexibility and power, ultimately increasing risk of re-injury. It is critical to identify a hamstring strain early, treat it appropriately, and use rehabilitation to improve strength and flexibility without worsening the injury.

Rehabilitation for hamstring injuries (see Table 2) can be a delicate balance of strengthening using eccentric force, but carefully incorporating other types of exercise, such as concentric force. Athletes and their trainers must also be careful to avoid returning to play too soon, as risk of re-injury is much higher if proper healing has not taken place. The key indicator for a return to action is when a player has completed all phases of rehabilitation and can perform sports-specific activities without pain or a sense of tightness in the previously injured hamstring. Studies report a lower incidence of hamstring injuries in certain football teams, while others have a higher incidence, suggesting not all clubs are as efficient in rehabilitating hamstring strains.2

There are a few risk factors for hamstring strains:

1.) Age/Race

Those with African-American or Aboriginal ethnic backgrounds have a greater frequency of hamstring strains. These racial groups have a higher amount of type II muscle fibers (‘fast-twitch’ fibers). Fast-twitch fibers are good at creating explosive movements, but make these athletes more prone to strains. Increased pelvic tilt might also contribute to this racial predisposition to injury.

 2.) Age

Older age increases risk of hamstring strain. Age cut-off appears to be those older than 24 years of age.3 Possible reasons might include increase in body weight, reduction in muscle mass, greater risk of lumbar strain and reduced flexibility in players older than 24 years of age. 3

 3.) Hamstring to quadriceps ratio (H:Q ratio)

Athletes with weaker hamstring strength relative to quadriceps strength are at greater risk for hamstring injuries. This makes sense, as this results in excessive extension of the lower leg, stretching the hamstrings too far, resulting in tearing of muscle fibers and hamstring strains.

4.) Fatigue

As fatigue builds up, neural input into the hamstrings may not be as coordinated compared to the fully energized state. The biceps femoris has two “heads,” or attachments, and each one is innervated by two different nerves (tibial vs common peroneal). If neural input is not precisely coordinated, as can happen during a fatigued state, the biceps femoris may not work synchronously, thereby increasing risk of muscle strain. This is likely the reason why many hamstring strains occur during preseason or practice, when conditioning may not be optimal. This is also the reason why smart NFL coaches like to have their players in optimal condition, and also why players who hold out may end up injured upon their return. Data exists to show greater frequency of strain injuries late in games, again supporting fatigue as a causative factor. Altered technique and reduced focus when fatigued might contribute.

5.) Insufficient warm-up

Most fans probably do not give it much thought when players are seen stretching before the game starts. This, however, helps to reduce risk of muscle strains. Muscles are primed to work most efficiently at a higher temperature, and warming up helps to get these muscles at the proper internal temperature before the real action starts. Studies show as little as 1 degree Celsius increase in temperature can substantially improve force absorbed and flexibility in hamstrings.

6.) Prior injury

A prior hamstring injury will increase risk for recurrent hamstring strains. As mentioned previously, this occurs when a blood clot or connective tissue replaces muscle fibers, and this puts a player at greater risk for recurrent hamstring strains. Studies have shown that a previously injured hamstring does not generate the same amount of force as a healthy hamstring, and this can lead to aggravation of the injury when the same amount of force is applied.3

Miles Austin has unfortunately been plagued by hamstring injuries the past two years. In 2011, he missed six games when he pulled both hamstrings. In 2012, he did not miss any games, but had another hamstring injury in preseason, and this chronic strain seemed to adversely impact him throughout the year. Repeated hamstring injuries can reduce strength, explosiveness, flexibility and make an athlete more hesitant to push it on the field. Austin seems to have a few red flags for re-injury of hamstring strains, including older age (28) and history of hamstring injuries (2011 and 2012). Looking at his 2012 numbers, referenced from Pro Football Focus (PFF), Austin finished 23rd in the NFL in slot performance, but 50th in deep passing efficiency (25% snaps or more). In 2009, when Austin had his finest season, he finished 15th in deep passing efficiency, but he has been on a downward trend, finishing 26th in 2010, 15th in 2011 and 50th in 2012. The plummet in deep passing efficiency is particularly concerning in 2012, as Austin missed the last six games of 2011 with both hamstrings strained, and this represents his post-injury performance. Deep passing efficiency would be adversely impacted by muscle strains, as such activity places significant stress on hamstrings. Time will tell if he can improve his performance as a deep threat, but another hamstring injury will severely impact his ability to regain optimal performance.

In terms of owning Austin, I would be selling him. He is at high risk for recurrent hamstring injuries, and each one will further reduce his on-field performance, thus rendering him less valuable both to your team and the Dallas Cowboys. In fact, Austin came close to be released after the 2012 season, and I have no doubt his recent history of hamstring strains and risk for recurrent injury played a big role in that thought process.

References

1. Elliott MC, Zarins B, Powell JW, et al. Hamstring Muscle Strains in Professional Football Players: A 10-Year Review. The American Journal of Sports Medicine, 2011;39(4): 843-850.

2. Petersen J, Holmich P. Evidence based prevention of hamstring injuries in sport. Br J Sports Med 2005;39:319-323.

3. Opar DA, Williams MD and Shield AJ. Hamstring Strain Injuries: Factors that Lead to Injury and Re-Injury. Sports Med 2012;42(3):209-226.

4. Sarwark JF. Essentials of Musculoskeletal Care, 4th Edition. 2010. Pages 231-233.

 Table 1

Hamstring strains2

Grade

Description

Recovery

1

A few muscle fibers torn, minor swelling and pain, minimal to no loss of strength or range of motion. 3 weeks.

2

More damage to muscle with loss of strength. 4 to 6 weeks.

3

A complete tear through the muscle that prevents movement. 3 months or longer.

Table 2

Treatment of Hamstring Injuries4

Phase Time Goals Treatment

1

1 to 7 days Reduce pain and inflammation, stop bleeding, prevent scar tissue. Rest, ice, compression, elevation, NSAIDs*,, stretching.

2

3 days to 3 weeks Control pain/swelling, full range of motion, maintain conditioning, improve muscle strength. Ice, compression, electrical stimulation, pain-free pool/range of motion/bike exercises.

3

1 to 6 weeks Control pain/swelling, increase strength and flexibility. Ice, compression, electrical stimulation, advancing exercise and stretching.

4

2 weeks to 6 months Return to sport, improve flexibility and strength. Control pain. Return to play, stretching, exercises continued, heat, ice, NSAIDs* as needed.

5

3 weeks to 6 months Avoid re-injury. Maintenance stretching and exercise.

*NSAIDs = Non-steroidal anti-inflammatory drugs (Motrin, Advil, ibuprofen, aspirin)

9 Comments

9 Comments

  1. Eric Barrett

    March 23, 2013 at 5:07 am

    Any thoughts on MJDs lisfranc fracture ???

    • Scott Peak

      March 23, 2013 at 6:42 pm

      Hey, Eric. Great question. That sounds like an interesting article to write. 🙂

      I’m not a fan of football players with foot injuries, particularly of the Lis-Franc variety. Still, surgery can help improve recovery for these kind of injuries. Re-injury can be hard to predict, and anatomy of the foot is very, very, very complicated. So, it’s buyer beware. However, MJD’s value is heavily discounted right now, so a contending team could take a chance on him in 2013. I love MJD’s attitude, and he recently commented on getting 2000 yards in 2013, like AP. Still, I would only trade for him at a discount, and that depends on whether his current owners feel the same.

  2. German Cowboys

    March 23, 2013 at 7:50 am

    Pelvic postural Dysfunctions and Spodylolithesis, as an example for vertebra postural dysfunctions, are other cause of hamstring-injuries.

    Therefore Hamstring-injuries are mostly caused by the individual player’s anatomy and pathophysiological biomechanics ; with other words , some players with certain anatomic and pathophysiological status of their bodies, tend to hamstring-injury , even if they do not have other prior injuries, despite their age and even if their warm-up program is perfect.

    you could make a case that the player with hamstring issue, could be defined injury-prone, if he has a significant anatomic postural dysfunction, which cannot be corrected easily.

    But a player , who had a hamstring injury, because of bad luck, or insufficient warm-up, cannot be called injury prone.

    In case of Miles Austin, without knowing his medical data, i would assume he could be called injury- prone , because of the occurrence of these injuries. That cannot be tough luck only.

    Fantasy-wise i would be caution to rely on Miles Austin as my lead WR on my team. On an explosive offense like the Cowboys, Miles Austin makes a good WR2 , just make sure your WR-corps is deep enough, if injury strikes again.

    • Scott Peak

      March 23, 2013 at 6:42 pm

      Thanks for the comments! Agreed.

  3. Brian

    March 23, 2013 at 9:48 am

    I’m a Physical Therapists Assistant and have absolutely loved your articles in regards to fantasy. I feel like knowing anatomy has always given me sort of a leg up on my league mates. Keep it up!

    • Scott

      March 23, 2013 at 6:36 pm

      I have a friend who’s a physical therapist and there’s quite a few times I’ve consulted with her on my players injuries.. she finds my concern for my players humorous. lol

    • Scott Peak

      March 23, 2013 at 6:43 pm

      Thanks Brian! Just don’t pull a hammy getting that ‘leg up’. 😉

  4. Jacob Feldman

    March 23, 2013 at 9:52 am

    I’m guessing that it would be reasonable to lump Andre Johnson into the same category as Miles Austin given that Johnson has had career long issues as well.

    • Scott Peak

      March 23, 2013 at 6:45 pm

      Yes, I would do so. Johnson did rebound last year, though, so hopefully he is on the right track back.

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