What is something the Mets and Yankees have in common at the moment? The answer… a starting pitcher and second baseman on the DL with hamstring strains. Coincidently, even the timing was close.

The Mets lost starting right-hander Robert Gsellman to the injury on June 27th when he noted tightness in his left hamstring as he approached the mound after trying to beat out an infield single.

Less than two weeks earlier, on June 14th, Neil Walker, the Mets’ second baseman, partially tore his left hamstring while trying to leg out a bunt single.

Over in the Yankees’ clubhouse you’ll find second baseman, Starlin Castro, on the 10 day DL. Castro left the game on June 26th after trying to beat a ground ball that ended the third inningHis right hamstring injury sounds like a mild strain, with the player noting the current injury seems less severe than that suffered last season.

The remaining member of this NY hamstring support group is CC Sabathia. The Yankees’ veteran starter was having a great season before having to leave the game on June 13th due to a partial left hamstring tear. Unlike the others, Sabathia hurt his hamstring while pitching. Initially thinking the muscle was cramping he threw one more pitch before realizing otherwise.

Three of these four players suffered strains when sprinting, an activity during which the hamstrings are quite vulnerable. Why is that?

First a little anatomy

There are three muscles in the hamstring group: Semimembranosis, Semitendinosis, and Biceps Femoris, which has a long and short head.

For the most part, the muscles originate at the lower pelvis at a bony knob you can palpate in your lower butt called the ischial tuberosity. The semitendinosis inserts below the medial (inner) aspect of the knee at the upper tibia, while the semimembranosis and biceps femoris attach primarily to the outer aspect of the region below the knee: at the lateral fibular head, the lateral condyle of the tibia, at the posterior lateral capsule and at the fascia in the lateral leg.

As a group, the hamstrings are responsible for extending the hip and for flexing the knee. Other functions of the hamstrings are to provide dynamic rotary stability at the knee, and prevent forward translation of the tibia on the femur, contributing to stability in that plane of motion as well.

When the limb is fixed and hamstring functions with a reversal of its origin and insertion, the hamstrings assist in providing stability at the pelvis, and they act to extend the pelvis on the hip (rather than extending the hip on the pelvis). This is what takes place in the dead lift.

As with all muscle strains, those at the hamstrings are graded either as Grade 1: a mild pull of the muscle, Grade 2: a partial tear, or Grade 3, a complete rupture. Ruptures that take piece at the origin or insertion of a tendon and that take a piece of bone with them are called avulsions.

Common areas of injuries to the hamstrings are at the musculotendinous junction – where the muscle transitions to tendon – or in the thicker muscle belly.

What causes strains?

When the demand placed on tissue exceeds its ability to perform, the tissue is injured. In the case of the hamstrings, this often occurs when the muscle is stretched beyond its limits of flexibility – as when a first baseman stretches out to make a tough play – or when the muscle is overloaded.

Eccentric contractions – when a muscle is lengthening while still contracted and exerting tension – are one way in which muscles can be loaded. Of course, adding weights when training, or body weight with activity, compounds that load.

Because hamstring strains often occur while the muscle is contracting eccentrically, using eccentric exercise in a training program can be essential in helping to decrease vulnerability. Though studies have shown this to be the case, interestingly, these same studies found eccentric training did not reduce the severity when injury did occur, or lessen the likelihood of re-injury.

So why sprinting?

A number of studies have demonstrated that hamstring strains are most likely to occur in late swing before foot strike and in late stance before takeoff.

As the back leg is straightened and the toes are pushing off to propel the limb forward, the hamstrings are lengthened at the knee yet contracting as well. The load is heightened by an athlete’s body weight, while the need for power and speed also increase the demand. Eccentric strength is key.

In addition, a sudden activation during an eccentric contraction has been shown to cause more severe muscle injury.

Other factors that predispose to hamstring strains can be muscle weakness and/or a low ratio of hamstring to quadriceps strength. Diminished muscular endurance (leading to more rapid muscle fatigue with activity) and other strength imbalances throughout the lower kinetic chain and core can also lead to a higher incidence of hamstring strains. A number of studies point to hamstring tightness as a predisposing factor (though this requires further study) as do some that fault insufficient warm-up.

As for the latter, it is important to note that current thought is to warm up dynamically rather than focus on static stretching. Research has demonstrated that employing static stretching as a warm-up activity can actually briefly inhibit muscle strength. After exercise or activity, when the body is already warmed up, is the ideal time to include static stretches in your routine to improve muscle flexibility.



About the author

Abby serves as the Injury Expert for CBS New York where, since 2010, her Injury Breakdown Blog examines injuries in professional sports. She also blogs on health & fitness as well as sports injuries for Huffington Post, and Recovery Physical Therapy.com, where her blog earned a top ten mention for physical therapy blogs in 2012 @ WorldWideLearn.com. In a ranking of the Top 30 Healthcare Blogs for 2012, Top Masters in Healthcare also rated Abby’s blog in the top three in Physical Therapy! Abby is the founder of Fit-Screen and she welcomes your comments and questions!