Hamstring Strain in High School Athletes
Condition: Strains Thigh
MeSH terms: Sprains and Strains
Study type: Interventional

Summary: 
      The purpose of the current study is, 1) Determine the effectiveness of injury prevention
      programs for prevention of hamstring muscle strains, 2) Identify how these programs impact
      athletes' flexibility, muscle stiffness, strength, and power, and 3) Determine the ability of
      a state-of-the-art imaging technology, shear wave elastography to predict future hamstring
      muscle strain injury.
    

Detailed description: 
      Hamstring strains are a significant problem for basketball athletes across levels of play for
      both sexes. The impact of hamstring muscle strains (HSMS) is significant. Injuries typically
      result in persistent symptoms and lengthy recovery periods which limit the athlete's practice
      and play time. Even more significantly, HSMS have high rates of reinjury. It is estimated
      that approximately one-third of hamstring strains are recurrent. Given the high incidence of
      HSMS and the substantial tendency for injuries to recur, it has been advocated the greatest
      impact may be achieved by the development of improved techniques for prevention of initial
      injury.

      Multiple risk factors for HSMS have been identified. Perhaps the strongest modifiable risk
      factor associated with HSMS is an imbalance between quadriceps and hamstring strength,
      specifically the eccentric hamstrings and concentric quadriceps strength ratio. The rationale
      is that sufficient eccentric capacity of the hamstring muscles is necessary to offset the
      concentric quadriceps contraction during the terminal swing phase of running. Not
      surprisingly, prevention programs that emphasize eccentric hamstring strengthening have been
      effective in reduction of HSMS injury rates.Prospective studies have demonstrated mixed
      results regarding the relationship between hamstring flexibility and hamstring injury, and
      the effectiveness of a flexibility program for reduction of the incidence of HSMS remains
      controversial. Stretching duration, frequency, timing of stretching relative to sports
      activities and the type of stretch being performed have been suggested as important factors
      in the effectiveness of a flexibility program at reducing injury occurrence. In addition,
      reduced hip flexor and quadriceps flexibility has been identified as a risk factor for HSMS.
      Further investigation is necessary to determine if a flexibility program that addresses both
      anterior and posterior thigh musculature reduces injury risk. The role of neuromuscular (NM)
      deficits as a risk factor in HSMS injuries is unclear. Inclusion of NM exercises in a six
      week training period improved lower extremity control and movement discrimination, which has
      been suggested to contribute to HSMS injury prevention. However, the impact of a NM injury
      prevention program on HSMS rates has not been established.

      Sheer wave elastography (SWE) represents an emerging imaging technology. This real-time
      imaging technique evaluates the local mechanical properties of muscles. Thus, SWE has the
      potential to provide more sensitive insight into muscle stiffness than flexibility
      assessment. Recent studies have utilized this technique to evaluate the effect of lower
      extremity positioning on hamstring stiffness. The relationship between stiffness measures
      obtained using SWE and HSMS has not, however, been established.

      Key gaps in knowledge regarding HSMS injury prevention programs remain. Most critically, the
      effectiveness of HSMS prevention programs among basketball athletes is unknown. Furthermore,
      the comparative effectiveness of eccentric, flexibility, and NM training for reduction of
      HSMS injuries is also unknown. Assessment of lower extremity strength, rate of power
      production, flexibility, and stiffness (captured with SWE) may elucidate the mechanisms
      underlying the effectiveness of injury prevention training, and aid in enhancement of injury
      prevention programs. Thus, the potential impact of this proposal is profound as our
      investigative team aims to fill these gaps in knowledge. Ultimately, the results of this
      study have the potential to 1) reduce injuries among basketball athletes and consequently
      enhance and lengthen athletic careers, 2) provide scientific rationale underlying the effects
      of HSMS injury prevention training, and 3) determine if a novel ultrasound imaging technique
      may be effective in determining risk for HSMS.
    

Intervention name(s): Stretching; Strengthening; Neuromuscular
Intervention type(s): Other; Other; Other
Intervention description(s): Lower extremity flexibility exercises will be performed; Eccentric hamstring strengthening exercises will be performed; Dynamic lower extremity balance and movement control exercises will be performed
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: This is a prospective, randomized, repeated measures single- blind clinical trial.
Masking: Single (Investigator)
Primary purpose: Prevention
Keywords: hamstring; ultrasound; intervention