The Importance of the Hamstring Strength in Reducing Injury Risk in Netball Players

Amongst the many team ball sports accessible to the youth of Australia, netball is one of the most popular sports for young Australian females. The nature of the game involves high intensity and high impact movements, which can impact the growing body of youth female athletes thus rendering them susceptible to injury. These movements often include rapid acceleration, deceleration, and changes in direction, whilst at times performing jumping and/or landing movements. As a result, young female netball athletes are more susceptible to injuries in the knee, particularly concerning their Anterior Cruciate Ligament. This important ligament is more commonly known as the ACL.

The difference in incidence of ACL injuries between male and female athletes is alarming. With female athletes being 4-6 times more likely to sustain an ACL injury than males. In particular, younger netball athletes are at even HIGHER risk of ACL injury. With the peak incidence occurring between ages 14 and 16. Reasons for this discrepancy are widespread and not fully understood in the literature, however it appears to be a combination of structural, muscular, biomechanical and hormonal factors.

A common factor increase young female athletes risk of ACL injury is in-effective co-activation of the hamstring and quadriceps muscle. Co-activation refers to two muscles activating in synchronization. The quadriceps and hamstring muscles support ligaments around the knee, assisting in reducing large external loads applied to the joint. Efficient quadriceps and hamstring co-activation protects the knee joint from injury risk factors such as knee abduction and valgus knee motion. Also known as ‘knocked knees’ – a term you may have heard before, which is used to describe the act of the knees coming together.

Your quadriceps play an important role in straightening your knee, whilst your hamstrings bend your knee. A strength imbalance between these two muscle groups increases risk of injury. Often, female athletes have a large imbalance between the quads and hamstrings. With the quads being much, much stronger then the hamstrings.The hamstrings play a significant role in deceleration and protecting the knee joint, particularly during landing. A poor quadriceps to hamstring strength ratio increases the risk of valgus knee movement during landing and therefore overall ACL injury potential.

During and following puberty the hamstring to quadriceps strength ratio deficit starts to emerge in female athletes. Quadriceps strength increases relative to increases in height and body mass. However, this is not seen with the hamstrings which remain the same. This creates a large strength imbalance. Several studies have shown females generally have increased quadriceps activation and decreased hamstring activation when landing, running, side cutting and crosscutting. This increases load on the ACL, increasing risk of injury. If the hamstrings cannot activate effectively, increased load is placed on the ACL thus increasing potential for knee valgus motion, putting the ACL at risk of injury. 

High incidences of ACL injuries sustained by young female athletes demonstrate the need to implement effective injury prevention programs such as strength training to improve muscular strength, neuromuscular efficiency (the ability of the nervous system to recruit the correct muscles and produce force) and movement competency.

If you want to prepare your young female netball athletes for game intensity, athletic development, improve performance and prevent injuries it is important to implement an integrative and appropriately designed strength training program.

Programs involving resistance and plyometric training for young female netball athletes increase co-activation of the hamstring and quadriceps muscle group. Increased quadriceps and hamstring co-activation improves joint stability, movement efficiency and muscular control to prevent lower body injuries. This is important in supporting the ACL during movement and effective in reducing risk factors associated with ACL injury in female netball athletes. Such as improving knee bending and straightening range of movement (ROM) during landing as well as decreasing the ‘knocking knee’ movement.

It is optimal to introduce NMT to female netball athletes pre-adolescence as after age 14, female athletes may have developed altered joint mechanics due to the changes that occur during maturation. A combination of plyometric and resistance training is most effective for decreased ACL injury risk with more prominent results in female netball athletes under 18 years of age (1).

For the greatest preventative effects, under guidance of a qualified and experienced strength and conditioning coach, a strength training program inclusive of 2 or more sessions per week, for 30 minutes or more should be implemented. It is important to involve hamstring-strengthening exercises to counterbalance the anterior shear force (angled force on front of the knee) produced by quadriceps to protect the ACL.

Plyometric exercises that demonstrate improved hamstring strength that should be included involve exercises such a depth jumps, single leg hurdle hops, single leg push off, broad jumps and split squat jumps (2). Resistance exercises should also be included for the lower body such as back squat, lunges, barbell split squats and of particular importance to the hamstring muscles the Romanian deadlift, Nordic lowerings, glute bridges and hip thrusts.

Technique focus during NMT programs is crucial and load should only be increased if movement in each exercise is performed correctly. Incorporating and emphasizing deep knee flexion during plyometric and strength exercises significantly improves knee bending during landing as they involve greater recruitment of the hamstrings (3).

If you want to see results in the reduction of ACL injuries in your young female netball athletes, compliance and applying progressive overload (incremental loading of exercises over a period of time) are essential to facilitate long-term physical adaptation.

In summary, the occurrence of ACL injuries can be reduced drastically in young female netball athletes by increasing hamstring strength. If you have any questions about how you can increase your hamstring strength to prevent injury in netball, email me at [email protected]

 

References

  1. Myer GD, Sugimoto D, Thomas S, and Hewett TE. The Influence of Age on the Effectiveness of Neuromuscular Training to Reduce Anterior Cruciate Ligament Injury in Female Athletes: A Meta-Analysis. The American Journal of Sports Medicine 41: 203-215, 2013.
  2. Struminger, A. H., Lewek, M. D., Goto, S., Hibberd, E., & Blackburn, J. T. (2013). Comparison of gluteal and hamstring activation during five commonly used plyometric exercises. Clinical biomechanics, 28(7), 783-789.
  3. Myer GD, Ford KR, Palumbo J, and Hewett TE. Neuromuscular Training Improves Performance and Lower Extremity Biomechanics in Female Athletes. Journal of Strength & Conditioning Research 19: 51-60, 2005.