Let's start out with a simple game of word association. When I say, "baseball injuries" you say…

Most, if not all, of you had “shoulder, elbow, or the infamous Tommy John” come to mind immediately. If not, you certainly thought of an upper body injury. While those injuries are undoubtedly important when considering prevention, the lower body must also not be neglected. Let’s consider and focus on the hamstring group. Baseball players are asked to exert maximal force on their hamstring muscles from an immobile position, and this is done often during a single game. Whether sprinting down the baseline trying to beat a base hit or fielding a ball, forces exerted on the hamstring are neither in a single plane nor a single direction. With that being said, not only does a trainer need to consider the stresses, but he also must consider the surface on which baseball is played. Take into consideration the infield vs. the outfield, grass, vs. sand, grass vs. field, turf vs. AstroTurf (or turf variations)...but now you also need to add bumps, hills, divots, and bases to the equation! This is where your personal trainers, strength and conditioning coaches, athletic trainers, and physical therapists live, and this is where I will begin, focusing primarily on injury prevention.

In understanding the importance that eccentric (lengthening) contractions play in injury prevention, it is imperative to have a background in why injuries, particularly to muscles, occur in the first place. Muscle strain injuries are thought to occur when muscles are actively lengthened to greater than normal lengths. Only the combination of an active muscle being lengthened will produce the mechanical strain that can cause a muscle injury.

The length-tension relationship suggests that, under most normal movement conditions, the body, either through motor control or biomechanical strategies, attempts to optimize muscle length so that maximal force, torque, and power can be produced. The descending portion of the length-tension curve (RED) is thought to be the region of vulnerability since, at this point, total tension (GREEN) is subsequently increasing, as is the length of the muscle. Current research suggests that athletes who produce peak tension at shorter lengths are more likely to be injured. Thus, if optimum lengths of muscle tension could be shifted to longer lengths, those athletes would be less susceptible to injury.

Length tension curve of a muscle 123014

So Where is the Relevance?

When you consider a muscular contraction, you may think of a simple motion such as a bicep curl. During the initial part of the curl, your biceps are concentrically contracting (or shortening); however, what about the second portion of the exercise? During the descending portion of the bicep curl, the bicep must control the descent of the weight being held; otherwise, your arm would simply drop. Here, the bicep is contracting eccentrically, meaning contracting while simultaneously lengthening.

Multiple studies have concluded that eccentric contractions tend to shift the optimum length of tension development to longer lengths (pushing the length tension curve to the right) in such muscles as elbow flexors, foot plantar flexors, knee flexors, and extensors. Three main variables have been determined to affect this shift, including intensity of eccentric exercise, volume of eccentric exercise, and length of the muscle during eccentric contraction. Interestingly enough, the exercise does not have to be of high intensity. High intensity eccentric contractions have actually been found to increase muscle damage in order to obtain length changes.

In summary, eccentric exercises can help to prevent injuries by shifting the length tension relationship of a muscle to longer, less vulnerable lengths.

hamstring injury exercises baseball 123014

Ten Helpful Exercises to Prevent Hamstring Injuries:

Target:

Biceps Femoris

O: Long head: upper inner quadrant of posterior surface of ischial tuberosity. Short head: middle third of linea aspera, lateral supracondylar ridge of femur

I: Styloid process of head of fibula. lateral collateral ligament and lateral tibial condyle

A: Long head: Hip extension. Short head: Flexes and externally rotated the knee

Semimembranosis

O: Upper outer quadrant of posterior surface of ischial tuberosity

I: Medial condyle of tibia below articular margin, fascia over popliteus and oblique popliteal ligament

A: Flexes and medially rotates knee and extends hip

Semitendenosis

O: Upper inner quadrant of posterior surface of ischial tuberosity

I: Upper medial shaft of tibia below gracilis (Pes anserine)

A: Flexes and medially rotates knee and extends hip

Foam rolling copy 123014

1. Foam rolling

  • While long sitting over a foam roller, sweep all three hamstring muscles by internally and externally rotating your hips, taking note to tender spots.
  • Once tender spots are found, target by completing small rolls over spots, gradually working to bigger rolls. Repeat on all tender spots.

single leg russian dl 123014

2. Single-Leg Russian Dead Lifts

  • Start in a single leg stance with weight in contralateral (opposite) hand.
  • Slowly flex at your hips, keeping ipsilateral knee slightly flexed (~10-20 degrees) and contralateral leg extended. Slowly bring weighted hand to single limb stance leg.
  • Return to extended position.

Nordic Exercise copy 123014

3. The Nordic Exercise

  • In a tall kneeling position on an airex pad or mat of your choice, have a partner hold ankles.
  • Slowly extend your knees and lower your body to the ground with your hips forward, keeping a straight line from knee to shoulder.
  • Use your hands to halt progression and propel yourself back into starting position.

Eccentric Hamstring Curls copy 123014

4. Eccentric Hamstring Curls on Cybex Machine

  • Sitting in an upright position, position a thigh immobilizer above the patella so as to not hinder patella movement throughout range of motion.
  • Place lower leg bar just above Achilles tendon. Curl by flexing knees, slowly return to knee extension with a 10 count.

stability ball bridge 123014

5. Stability Ball Bridge and Curl

  • Lye in a supine (on back) position with you arms at a 45-degree angle away from your body to support yourself.
  • Place your heels on a stability ball, press you heels into the ball, and bridge your hips.
  • Flex your knees and hips to curl stability ball underneath yourself, then slowly return to the starting knee and hip extension.

Resisted partner pushing 123014

6. Resisted Partner Pushing

  • With a partner, interlock your arms at shoulder level.
  • Let your partner dig in and begin to push you backwards as you resist while taking backwards steps.
  • This exercise targets both eccentric and concentric activation of the hamstring musculature.

Single leg star copy 123014

7. Single-Leg Star or Y Pattern Excursions

  • In a single-leg stance with ipsilateral hip and knee slightly bent, contralateral hip flexed and knee extended, begin exertion to front position, slightly squatting with ipsilateral leg.
  • Bring contralateral heel out as far as possible.
  • Repeat in Y or star pattern.
  • To progress, complete on Bosu.

Eccentric walking lunges copy 123014

8. Eccentric Walking Lunges

  • With or without dumbbells, complete walking lunges, slowly dropping your knee to the ground (with a three- to five-second count) and keeping your hip aligned with your knee as to not to overextend.
  • Repeat until fatigued.

TRX jump squat 123014

9. TRX Jump Squats

  • Holding onto TRX straps, perform a double-limb squat and propel with a jump into the air.
  • Upon decelerating to the ground, slowly return to squatting position.
  • Repeat until fatigue.

Self hamstring stretch copy 123014

10. Self Hamstring Stretch (post workout)

  • Lying in a supine position, place bilateral legs flat against the ground, keeping contralateral knee pressed against ground or rolled up towel.
  • Use stretching strap to flex ipsilateral leg at hip, keeping knee fully extended.
  • Hold stretch for approximately 30-45 seconds and repeat four times.

References

  • Brughelli, M., Cronin, J. Preventing hamstring injuries in Sport. Strength and Conditioning Journal 30: 2008
  • Bowers, E., Morgan, D., and Proske, U. Damage to the human quadriceps muscle from eccentric exercise and the training effect. J Sports Sci 22:1005-1014, 2004.
  • Brockett, C., Morgan, D., and Proske, U. Human hamstring muscles adapt to eccentric exercise by changing optimum length. Med Sci Sports Exerc 33: 783-790, 2004.
  • Clark, R., Bryant, A., Culgan, J., and Hartley, B. The effects of hamstring strength training on dynamic jumping performance and isokinetic strength parameters. Phys Ther Sport 6: 67-73, 2005.
  • Philipou, A., Bogdanis, G., Nevill, A., and Maridaki, M. Changes in the angle-force curve of human elbow flexors following eccentric and isometric exercise. Eur J Appl Physiol 93:237-244, 2004.