Why you should be performing Nordic Hamstrings
As strength and conditioning coaches we’re all about injury prevention. Time out of sport is boring, it wastes money and can take a long time to return, not just physically but psychologically. We all know and accept that injuries do happen and unfortunately are part of sporting life, but some can be avoidable. For me, non-contact injuries should be very low on the injury list, especially injuries to the posterior chain – Gluteals, Hamstrings and Erector Spinae.
There are, like most muscle groups, so many exercises to choose from when looking to train the posterior chain, and in this particular instance, the hamstrings. The hamstrings are a unique group of 3 muscles; the Biceps Femoris, Semimembranosus and the Semitendinosus. They are bi-articular, which means they run over 2 joints, which also means they have 2 major functions. Firstly they are knee flexors, similar to what the biceps are in the arm when flexing the elbow, the hamstring flexes the knee. They are also hip extensors, these are the muscles that straighten you back up when bent at the hip.
Because they are bi-articular the hamstrings play a major role in most lower body movements, and especially running based movements. 16-23% of injuries in selected team sports (Arnason, Andersen, Holme, Engebretsen, & Bahr, 2004; Brooks, Fuller, Kemp, & Reddin, 2005) are hamstring injuries and 29% (Lysholm & Wiklander, 1987) in track and field. Which concluded in an average injury time of 18 days. As a sports person it is tough to rehab and try to come back from injuries. Over the years I have attempted to develop my knowledge to understand what happens during hamstring injuries and when the hamstrings are most vulnerable. Through out my learning it has become a theme of mine to focus on eccentric hamstring strengthening as I believe it to be one of the most valuable weapons a strength coach can have in his armoury It has been found that eccentric training can reduce injuries by up to 60 to 70% (Brughelli & Cronin, 2008).
When we run, the hamstrings go through larger than usual ranges of movement (Thelen, Chumanov, & Hoerth, 2005), especially during late swing phase when hips are flexed and leg extended which can put huge amounts of strain through the hamstring, particularly the Biceps Femoris, this is also the most common time in which hamstring injuries occur (Clark, Bryant, Culgan, & Hartley, 2005). In a study it was found that the Biceps Femoris accounted for 80% of total hamstring injuries amongst a cohort of 170 individuals with injured hamstrings (Koulouris & Connell, 2003).
The idea is that through eccentric training we can strengthen the hamstring whilst it is lengthening, with the hope that we can increase the optimum length in which the hamstring produces maximal force and therefore limit injuries (Brockett, Morgan, & Proske, 2001). Studies have shown that through eccentric strengthening, namely the Nordic hamstring curl, this can be achieved. Tests have been done at high volumes of 12 sets of 6 (Brockett, et al. 2001), and lower levels of 2-3 sets of 6-8 (Clark et al. 2005), both of which showed hamstring optimum force length to be increased. It is worth noting however, that the large volume used by Brockett et al. of 12 sets of 6 reps, is not needed as the DOMS (Delayed Onset of Muscle Soreness) that could be felt following this has shown to be enough for athletes to not want to continue, plus it is not sport specific and will not help to enhance training as loads will have to be lower as the athletes recover. There is evidence to suggest that 1 set of 5 reps with a strict 3-second eccentric is enough to fatigue the hamstring and therefore start the process of lengthening the optimal force angle (Marshall, Lovell, Knox, Brennan, & Sieglar, 2015).
Studies have shown that whilst the Nordic Hamstring exercise is not the most effective recruiter of the Biceps Femoris (Zebis, et al., 2013), that award is given to the supine leg curl and prone hip extension, it is however a valuable bodyweight exercise that can be used extensively in hamstring strengthening programmes It has also been suggested that is can be used as a precursor to injury when looked at force and/ or ‘break point’ of the exercise, as the breakpoint angle significantly correlates with peak concentric hamstring torque (Sconce, Jones, Turner, Comfort, & Graham-Smith, 2015). If you ‘break’ (cannot control your lowering any more) at a higher angle, i.e., closer to the start, there is evidence to suggest you are more susceptible to hamstring injury. The study concluded that although more research needs to be conducted on the use of the Nordic Hamstring Exercise as a repeatable test, the results do show that it is a reliable assessment.
There is an argument that as the exercise is unilateral in nature there could be more development in one hamstring over the other, however, studies have proven that whilst the hamstrings didn’t completely balance out, the average limb balance between left and right did improve significantly over a training period (Opar et al., 2015). Contraty to popular belief an imbalance of up to 20% between each leg does not increase chance of injury. Opar et al., work corresponds with Sconce et al., where both have found that low levels of eccentric hamstring strength was a precursor for injury. If you could test both eccentric hamstring force and break point angle, then you might have the opportunity to identify hamstring strain probability in your athletes.
The Nordic Hamstring exercise should be on all your exercise programmes. Yes it should be rotated, and yes it can be supplemented with other great hamstring and posterior chain exercises, but amateur athletes especially who don’t have huge amounts of equipment and need to start bringing this exercise in to their training regime just 2 sessions per week (Clark et al, 2005). For me the Nordic Hamstring curl is King of all hamstring eccentric exercises and will always be a part of my athletes training.
Reference List
Arnason, A., Andersen, T. E., Holme, I., Engebretsen, L., & Bahr, R. (2004). Risk factors for injuries in football. American Journal of Sports Medicine , 32.
Brockett, C., Morgan, D., & Proske, U. (2001). Human hamstring muscles adapt to eccentric exercise by changing optimum length. Medicine and Science in Sports and Exercise , 33, 783-790.
Brooks, J., Fuller, C., Kemp, S., & Reddin, D. (2005). Epidemiology of injuries in english professional rugby union, part 1: match injuries. British Journal of Sports Medicine , 39, 757-775.
Brughelli, M., & Cronin, J. (2008). Preventing hamstring injuries in sport. Strength and Conditioning Journal , 30 (1), 55-64.
Clark, R., Bryant, A., Culgan, J.-P., & Hartley, B. (2005). The effects of eccentric hamstring strength training on dynamic jumping performance and isokinetic strength parameters: a pilot study on the implications for the prevention of hamstring injuries. Physical Therapy in Sport , 6, 67-73.
Koulouris, G., & Connell, D. (2003). Evaluation of the hamstring muscle complex following acute injury. Skeletal Radiology , 32, 582-589.
Lysholm, J., & Wiklander, J. (1987). Injuries in runners. American Journal of Sports Medicine , 15, 168-171.
Marshall, P. W., Lovell, R., Knox, M. F., Brennan, S. L., & Sieglar, J. C. (2015). Hamstring fatigue and muscle activation changes during six sets of nordic hamstring exercise in amateur soccer players. Journal of Strength and Conditioning Research , 29 (11), 3124-3133.
Opar, D. A., Williams, M. D., Timmins, R. G., Hickey, J., Duhig, S. J., & Shield, A. J. (2015). Eccentric hamstring strength and hamstring injury risk in australian footballers. Medicine and Science in Sports and Exercise , 47 (4), 857-865.
Sconce, E., Jones, P., Turner, E., Comfort, P., & Graham-Smith, P. (2015). The validity of the nordic hamstring lower for a field-based assessment of eccentric hamstring strength. Journal of Sport Rehabilitation , 24, 13-20.
Thelen, D., Chumanov, D., & Hoerth, M. (2005). Hamstring muscle kinematics during treadmill sprinting. Medicine and Science in Sports and Exercise , 38, 108-114.
Zebis, M. K., Skotte, J., Andersen, C. H., Mortensen, P., Petersen, H. H., Viskaer, T. C., et al. (2013). Kettlebell swing targets semitendinosus and supine leg curl targets biceps femoris: an EMG study with rehabilitation implications . 47 (18), 1192-1198.
