IN THIS ISSUE
Read this article »
Read this article »
Read this article »
Read this article »
Athletic Training Services Team
Texas Medical Center/San Jacinto
Bene Barrera ATC, LAT
Jeff Collins, LAT
Jace Duke, ATC, LAT
Emery Hill, ATC, LAT
Terry King, LAT
Michelle Leget, ATC, LAT
Ha Nguyen ATC, LAT
Caitlyn Prescott ATC, LAT
Scott Tidwell, LAT
Jerry Meins, ATC, LAT
Stephen Melancon, ATC, LAT
Brandon Roberts, ATC, LAT
Bill Wissen, ATC, LAT
Richard Gregoire, ATC, LAT
Layne Schramm, ATC, LAT
Dwight Adsit, ATC, LAT
Paula Douglas, ATC, LAT
Keith Jahn, ATC, LAT
Mike Pace, ATC, LAT
Prevention of Hamstring Injury
Strains of the hamstring muscle group are a considerable cause of disability in athletics. The majority of hamstring injuries occur during pre- and early-season activities. Sprinting athletes, who are characterized by their explosive power and great stride length, are at a particularly high risk for injury. A clear need exists for preventative interventions, and conditioning regimens that may help decrease injuries to the hamstring muscle group.
The hamstring muscle group is comprised of three main muscles of the posterior fascial compartment of the thigh: the biceps femoris, which consists of two parts – the long and short heads - and runs along the outside of the leg and inserts into the head of the fibula; the semitendinosus is located along the inside of the leg and inserts on the front of the tibia; and the semimembranosus runs along the same path but underneath the semitendinosus and also inserts on the front of the tibia.
The unique biomechanics of the hamstring muscle group create multiple motions at the hip and the knee. Working together, the hamstring muscles cause flexion of the knee and extension of the hip. Specifically, the long head of the biceps femoris extends the hip during ambulation. Both short and long heads flex the knee and laterally (externally) rotate the tibia in knee flexion. The semimembranosus and semitendinosus muscles extend the hip when the trunk is stabilized. These two muscles also flex the knee and medially (internally) rotate the tibia when the knee is bent.
During the swing-through phase of ambulation, the hamstring muscle group acts as a hip extensor and a knee extension decelerator. When performing an action such as sprinting, the forces generated across the hamstrings are significant.
The hamstring muscles play a crucial role in the deceleration of knee extension when walking or running and deceleration of knee extension is a common cause of hamstring strains. Deceleration of knee extension is an agonistic action performed by the hamstring muscles against the movement of the quadricep muscles. This eccentric contraction (a contraction as the muscle lengthens) can create higher muscle tension stress than a concentric contraction (a contraction when the muscle shortens). During the swing-through phase of ambulation, the hamstring muscle group acts as a hip extensor and a knee extension decelerator. When performing an action such as sprinting, the forces generated across the hamstrings are significant. If the muscle group is not conditioned to handle these stresses, the muscles are at risk for injury.
Prevention of hamstring injury: To prevent hamstring injury, the muscles must be able to adapt to the stress demands placed on them. Strengthening of this muscle group consists of strength, power and endurance conditioning, as well as muscle relaxation and flexibility exercise. Remembering that the hamstring muscle group controls two joints, attention to conditioning in both knee flexion, as well as hip extension is imperative. Static hamstring curls address knee flexion, but it is necessary to also exercise hamstring contraction through the entire hip extension range of motion. It is critical to apply the overload principal both concentrically as well as eccentrically throughout the full range of motion of both knee flexion and hip extension. This exercise is easily achieved with elastic bands, as well as cable exercise machines. Core exercises to improve pelvic and trunk stabilization have been shown to reduce hamstring injuries.
Flexibility: A normal running stride is a fluid, coordinated movement free of muscular “tightness” with range of motion that is equal bilaterally. Athletes with soft tissue contractures, either from musculotendinous injury, weakness, or contracture are at risk of injury. Flexibility exercises are essential to improve muscle relaxation and range of motion.
A primary goal of athletes is to remain injury free during their training and competition seasons. Employment of basic conditioning principles as described may help in prevention of injury. All athletes, depending on body type, performance and sport skills, and conditioning levels can benefit from inclusion of a hamstring-specific conditioning and flexibility programs.
Friction Blister Care
Friction blisters are a common complaint of runners and other endurance athletes. A friction blister is a soft pocket of skin that is filled with clear fluid that typically results from continuous rubbing against the skin. This persistent assault to the skin causes irritation, minor damage and separation of the epidermal cell layers, which then fill with a clear, plasma-like liquid. When the friction injures a blood vessel, the pocket will fill with blood rather than clear fluid. Moisture increases this abrasive force and, therefore, the potential to form a blister. A study that investigated the advantages of acrylic over cotton socks in long distance runners found fewer and smaller blisters with the 100% acrylic socks due to the water retentive nature of cotton.
The most common site of friction blisters is the foot. Specifically, the tips of the toes, balls of the feet, and the posterior heel. Blisters may be painful, depending on their location and size. Generally, large blisters over bony prominences are exquisitely tender due to continued friction, compression, and the amount of weight the area supports.
Prevention of blisters is achieved by wearing dry, moisture-wicking acrylic or polyester socks and changing wet socks frequently. Wearing dual layer socks or two pair of socks during activity helps disperse friction between the sock layers. Shoes that fit properly play a critical part in blister prevention. The use of antiperspirant to reduce moisture and friction has been used by some athletes to help prevent blisters.
When excessive sweating (hyperhidrosis) is a contributing factor, absorbent talc powders can be used or the area can be soaked in 10% tannic acid. These measures may reduce moisture, although tannic acid and other astringents can cause minor skin discoloration. Botulinum toxin injections are also extremely effective for hyperhidrosis but the treatment is costly and the toxin has been associated with muscle weakness.
Small blisters usually resolve spontaneously if left untreated. Fluid is reabsorbed by the body and the underlying tissue thickens as the hood of the blister dries up. Large blisters, however, may interfere with activity and should be pierced and decompressed after disinfecting the blister hood and the surrounding skin. The blister should be pierced using a sterile needle or blade to puncture the blister in at least two areas near the periphery, which will allow the fluid to drain. A repeat puncture may be necessary if the blister margins close during healing.
The blister roof should be left intact to minimize the chance of infection and to aid in healing. Once a blister is punctured it becomes an open wound that is vulnerable to infection. After a blister has been pierced proper wound care with an antibiotic salve and bandage is required.
Further friction can be minimized with the application of a water and glycerin gel matrix. Placement of a moleskin covering over the bandage can help with continued friction. A small foam or felt “donut” pad around the blister can also prevent friction. Once pain and friction are relieved, the athlete may return to activity.