Dose Response of Nordic Hamstring Exercise on Performance in Athletes
Condition: Hamstring Injury
Study type: Interventional

Summary: 
      The aim of this research is to compare the effects of dose response of Nordic hamstring
      exercise on muscle strength, agility and speed in athletes a randomized controlled trial done
      at JKD cricket academy and sports centre, Peshawar. The sample size was 34. The subjects were
      divided in two groups, 17 subjects in Group 1 which will do high volume Nordic hamstring
      exercise and 17 in Group 2 which will do low volume Nordic hamstring exercise. Study duration
      was of 6 months. Sampling technique applied was non probability purposive sampling technique.
      Only 18-30 years athletes with BMI between 18.5-24.5 kg/m2 were included. Tools used in the
      study are Single leg hamstring bridge (SLHB), Agility t-test, 30-m speed test and muscles
      size .Data will be analyzed through SPSS 21.
    

Detailed description: 
      One of the most common injury in sports is the Hamstring injury, as hamstring is very
      susceptible to tears and strains. Hamstring muscle strain-type injuries are common in sports
      that involve high degree of speed, power and agility such as sprinters, soccer, basketball,
      tennis and football. Occurring in both recreational and professional sports, these injuries
      can result in substantial time lost from sport and commonly recur.

      When sprinting, the hamstring muscles of the swing leg function concentrically as hip
      extensors to quickly swing the thigh back, whereas the same muscle group acts eccentrically
      as knee flexors to decelerate the forward swing leg. This last action is a probable
      contributing injury mechanism because of the increased peak hamstring musculotendinous
      stretch, activation, and active lengthening contraction of the hamstring muscles. The Nordic
      Hamstring Exercise (NHE) was previously termed the 'Russian hamstring exercise'. This is a
      partner exercise which can be performed easily on the pitch without special equipment. The
      NHE involves the player attempting to resist a forward-falling motion from a kneeling
      position, eccentrically contracting hamstring muscles and thought to replicate hamstring
      function during terminal swing phase. NHE is a preventive strategy which may reduce the
      incidence of hamstring injury, medical costs, and personal suffering of the injured player
      keeping in view the training exposure, training intensity, and compliance to preventive
      measures. Programs that include the NHE reduce hamstring injuries by up to 51%. The NHE
      essentially halves the rate of hamstring injuries across multiple sports in different
      athletes. Even in the face of promising NHE preventive effect shown by previous
      studies,adoption and implementation of the NHE programs is still low. Evidence show
      improvement in performance, agility and speed in athletes by NHE training but lowest dose of
      NHE required to enhance athletes' performance , agility and speed is yet to be found. This
      study attempts to investigate the lowest dose response of NHE by comparing the effects of
      high volumes of NHE with low volumes of NHE.

      Literature review: Mjølsnes et al first demonstrated that a NHE program performed on the
      training environment of professional soccer players is more effective in developing maximal
      eccentric hamstring strength than a comparable program based on hamstring curl machine at the
      fitness center.

      Three large prospective trials (two randomized and one non-randomized) reduced injuries by
      approximately 70% by implementing the NHE in a team's training regime. The results from the
      meta-analysis suggested that teams using the NHE (in isolation or as part of a larger injury
      prevention program) reduced hamstring injury rates up to 51%.

      Brooks et al studied the effects of the NHE on the incidence and severity of hamstring
      strains among 546 professional rugby union players. The NH exercise group had a significantly
      lower hamstring injury rate and severity than the strengthening and the stretching/
      strengthening group.

      In a 2020, meta-analyses, positive outcomes were reported on jump performance, repeated
      sprint ability and agility of athletes after NHE protocol.

      A study conducted for 6 weeks concluded that NHE resulted in significant improvements in
      eccentric strength of hamstrings and performance in 10 m sprinters and also in change of
      direction speed immediately after the training protocol. These improvements remained even
      after 3 weeks of detraining.

      In a study NHE has shown improvements in strength and dynamic control after 10 weeks of
      training, a reduction in the maximum peak torque (when approaching full knee extension), and
      a lower incidence rate of hamstring injuries in athletes.
    

Intervention name(s): High volume nordic hamstring exercise; Low volume nordic hamstring exercise
Intervention type(s): Other; Other
Intervention description(s): To perform Nordic Hamstring Curls, the person will kneel on a pad (for knee comfort) and lower under control, his ankles must be stabilized and kept in a place with the help of a partner, but can also use a moveable object or a loaded barbell can also be used to achieve the stability. The person must then extend his hamstrings in order to lean forward, he should lean forward from the knee and not from the hip. The movement must be kept controlled and slow. The person should go as forward/low as possible but without the help of hands or arms. The only time one can put his hands in front of him is when he can't rely on his legs and then push himself back to starting position and then repeat the procedure again.Group 1 will do the Nordic hamstring exercise with protocol 3 repetitions × 3sets× 3 times for 4 weeks.; To perform Nordic Hamstring Curls, the person will kneel on a pad (for knee comfort) and lower under control, his ankles must be stabilized and kept in a place with the help of a partner, but can also use a moveable object or a loaded barbell can also be used to achieve the stability. The person must then extend his hamstrings in order to lean forward, he should lean forward from the knee and not from the hip. The movement must be kept controlled and slow. The person should go as forward/low as possible but without the help of hands or arms. The only time one can put his hands in front of him is when he can't rely on his legs and then push himself back to starting position and then repeat the procedure again. Group 2 will do the Nordic hamstring exercise with protocol 3 repetitions × 3 sets × 1 times for 4 weeks.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: Agility t test; Eccentric strength; Hamstring injuries; Nordic Hamstring exercises; Single leg Hamstring bridges