Change of direction biomechanical landmarks as performance and injury prediction markers
The ability to change direction in response to a stimulus is an important aspect of CoD performance in competitive environments, whereas most studies on CoD performance are limited by their controlled experimental nature, which is why it is difficult to establish direct correlations between biomechanical landmarks that could serve as indicators for performance and injury prediction, respectively (Fox, 2018). Furthermore, there is considerable variability between sports with regard to cutting and CoD strategy employed to evade opponents, as well as inherent sport and gender differences with regard to predisposition to injury during CoD and cutting manoeuvres (Bencke et al., 2013). This article will attempt to highlight some of the biomechanical features or landmarks that have been found to correspond with performance outcomes in CoD tasks, while also indicating biomechanical risk factors for injury in sports that involve cutting. Considerations for practical application will be provided for the practitioner, although it should be noted that the controlled nature of the suggested exercises cannot mimic the dynamic nature of team sports, where neural factors could have a decisive influence in both performance and injury prevention (Welch et al., 2019).
Change of direction as a key performance indicator (KPI) in team sports
A quick glance at top-class team sport reveals that change of direction ability is a key performance indicator, as it allows players to evade tackles, beat players and score goals or points, respectively. In football, for example, players have been found to make approximately 723 turns and swerves per game (Polman & O’Donoghue, 2007), and cutting ability has been successfully used in talent identification testing batteries to discriminate between elite and sub-elite players (Reilly et al., 2000). As the best team sports players are not necessarily also the best athletes, coaches need to rely on qualitative as well as quantitative assessment of movement competency in order to establish whether a player has the required abilities to perform at the elite level, which includes change of direction (CoD) performance. Nevertheless, quantitative analysis of cutting manoeuvres can provide practitioners with valuable information on athletes’ neuromuscular, biomechanical and mobility capacities, and can inform training programme design with respect to CoD performance.
Biomechanical landmarks influencing CoD performance
In a recent study, Marshall et al. (2014) found that five biomechanical factors were associated with cutting time: peak ankle power, peak ankle plantar flexor moment, range of pelvis lateral tilt, maximum thorax lateral rotation angle, and total ground contact time (see table below). This study looked at performance outcomes in a 75° cutting task within a controlled setting. Explosive force production about the ankle, pelvic control during single-limb support, and torso rotation toward the desired direction of travel were all key factors associated with cutting time. Given that power describes the ability to produce force quickly, it is not surprising that peak ankle plantar flexor moment and shorter ground contact times are also significantly correlated with cutting time. Although many muscle groups are involved in the multi-joint action of cutting, exercising the ability of the muscles contributing to peak ankle plantar flexor power, moment, and shorter ground contact times should be given greater emphasis. Although no ideal exercise that is best at enhancing these specific qualities while cutting has neem identified in research studies, plyometric exercises such as the countermovement drop jump may be particularly useful as they have been found to produce relatively large ankle plantar flexor moments, power outputs, and short ground contact times (Marshall et al., 2013). Marshall et al. (2014) found further support following work by Meyers et al. (2005) indicating that neuromuscular control of the pelvis is important during high-speed multidirectional sports, as it provides the anchor to facilitate dynamic locomotion. The Marshall study found that reduced pelvic lateral tilt (contralateral drop) during the knee flexion phase of the cut was associated with faster cutting times, while on the contrary, greater contralateral drop actually predisposed athletes to increased risk of abdominal and groin pain (Meyers et al., 2005). These findings suggest that the ability to produce explosive force about the ankle, maintain good pelvic control, and exhibit effective torso rotation were all related to performance ability. In terms of force vectors, the results obtained by Welch et al. (2019) highlight the importance of greater horizontal and rapid force production in cutting and greater reactive strength qualities to enhance cutting performance, which essentially means that the ability to produce a greater proportion of force horizontally is important for better CoD performance outcomes.
Furthermore, Young et al. (2002) suggested that cutting performance depends on 3 neuromuscular force production characteristics, namely maximum strength, explosive strength, and reactive strength. These seem to be necessary due to the various eccentric and concentric force demands observed during cutting and utilization of the stretch-shortening cycle. Shorter total ground contact time seems to have been consistently correlated with performance in cutting (Welch et al., 2019), indicating the time in which force is produced is important for performance. Welch et al. (2019) identified early rate of force development (RFD) as force production in periods under 100 ms, which may be important when reviewing neuromuscular assessment on instruments such as force plates. With all the cited studies done in a controlled environment, however, it would be interesting to be able to measure neuromuscular and biomechanical parameters in real-time game situations, when the neural factor becomes an even greater KPI.
Biomechanics of injuries during changes of direction
The biomechanical landmarks associated with injuries in CoD actions vary from sport to sport, although certain common markers exist. According to Hewett et al., (2010), there are four theories that explain the risk of ACL injury during a CoD action, after taking into consideration the gender factor that predisposes female athletes to a four to six-fold greater incidence of ACL injuries compared to their male counterparts while playing the same high-risk sports. The ligament dominance theory suggests that female athletes at high risk perform athletic manoeuvres with excessive knee valgus, hip adduction and hip internal rotation. Trunk dominance theory suggests that poor trunk control during athletic manoeuvres leads to increased risk for ACL injury. Quadriceps dominance theory suggests that excessive relative quadriceps forces or reduced hamstring recruitment place the ACL at high risk for injury. Finally leg dominance theory suggests that large leg-to-leg asymmetries predispose athletes to injury (Hewett et al., 2010).
Incidentally, the highest incidence of non-contact anterior cruciate ligament (ACL) injury in ball sports has been observed during handball match play, where it has been documented that young female handball players are the most susceptible to sustain an ACL injury (Bencke et al., 2013). The highest frequency of ACL injuries in handball is seen during non-contact side-cutting movements. The side-cutting manoeuvre in handball is usually very abrupt and explosive, with a very large angular change of direction, and this distinguishes the handball side-cut from other, more forward oriented, sports-specific movements like landing, drop jumping or side-cutting in, for example, football. Based on examinations of video recordings during handball play, Olsen et al. (2004) reported that the ACL injuries seemed to occur when performing a side-cutting manoeuvre with little knee flexion and with excessive valgus and knee internal or external rotation, which is supported by findings by Bencke et al. (2013) in that external loading during the handball side-cutting manoeuvre may force the knee into valgus and outward rotation unless counteracted by muscles or ligaments.
Performance and injury prediction: are we looking at the same landmarks?
While there are some common landmarks in CoD performance and injury prediction, such as contralateral pelvic drop, other biomechanical factors are not so conclusive and a narrower stance in cutting, along with soft landing and greater knee flexion, whilst minimizing risks of injury, actually reduces cutting performance (Fox, 2018).
In handball side-cutting manoeuvres, Bencke et al. (2013) observed external knee moments of flexion, external rotation and valgus, along with external hip moments of extension, abduction and internal rotation 30–40 ms after foot contact. Their results underline the importance of implementing preventive exercises that increase activity of medial hamstrings, to match the external outward rotating knee moments and knee valgus moments, and increase activity of hip external rotators to match the external hip inward-rotating moment.
A forefoot landing pattern along with trunk rotation and lateral flexion in the intended cutting direction were identified as biomechanical strategies that could both reduce potentially hazardous knee joint moments and enhance CoD speed. Minimizing knee valgus during change-of-direction manoeuvres may also reduce ACL injury risk, with this biomechanical strategy found to have no impact on performance (Fox, 2018).
For the strength and conditioning practitioner, one of the most important research findings is that the ability to cut quickly is dependent on the ability to produce large amounts of horizontal force rapidly (Welch et al., 2019). Marshall et al. (2015) suggest that plyometric training, pelvic control work, and cutting technique training may all be particularly useful in enhancing performance outcome. Plyometric training, including drop and bounce style drop countermovement jumps, could be a useful tool to prescribe in order to improve explosive force production at the ankle joint and reduce ground contact time while cutting. For both performance and injury prevention outcomes, pelvic control exercises should be prescribed in an effort to enhance frontal plane pelvic control during eccentric loading. Frontal plane control of the pelvis in single-limb stance is determined, at least in part, by the neuromuscular ability of the gluteal muscles, which should guide practitioners to prescribing exercises such as single-leg squats and single-leg stick and hold landings (see video series below). Trunk rotation exercises using medicine balls thrown in the desired direction of travel, coupled with augmented feedback during cutting drills may also be particularly useful. Augmented feedback has been known to improve performance and Myer et al. (2013) found that augmented feedback on deficits identified in a drop jump assessment resulted in a significant improvement in jumping technique.
Bencke, J., Curtis, D., Krogshede, C., Jensen, L. K., Bandholm, T., & Zebis, M. K. (2013). Biomechanical evaluation of the side-cutting maneuver associated with an ACL injury in young female handball players. Knee Surgery, Sports Traumatology, Arthroscopy, 21(8), 1876-1881. doi:10.1007/s00167-012-2199-8
Fox, A. S. (2018). Change-of-direction biomechanics: Is what’s best for anterior cruciate ligament injury prevention also best for performance? Sports Medicine, 48(8), 1799-1807.
Hewett, T. E., Ford, K. R., Hoogenboom, B. J., & Myer, G. D. (2010). Understanding and preventing ACL injuries: Current biomechanical and epidemiologic considerations – update 2010. North American Journal of Sports Physical Therapy: NAJSPT, 5(4), 234-251.
Marshall, B. M., & Moran, K. A. (2013). Which drop jump technique is most effective at enhancing countermovement jump ability, “countermovement” drop jump or “bounce” drop jump? Journal of Sports Sciences, 31(12), 1368-1374. doi:10.1080/02640414.2013.789921
Marshall, B. M., Franklyn-Miller, A. D., King, E. A., Moran, K. A., Strike, S. C., & Falvey, É. C. (2014). Biomechanical factors associated with time to complete a change of direction cutting maneuver. Journal of Strength and Conditioning Research, 28(10), 2845-2851. doi:10.1519/JSC.0000000000000463
Myer, G. D., Stroube, B. W., DiCesare, C. A., Brent, J. L., Ford, K. R., Heidt, R. S., & Hewett, T. E. (2013). Augmented feedback supports skill transfer and reduces high-risk injury landing mechanics: A double-blind, randomized controlled laboratory study. The American Journal of Sports Medicine, 41(3), 669-677. doi:10.1177/0363546512472977
Olsen, O., Myklebust, G., Engebretsen, L., & Bahr, R. (2004). Injury mechanisms for anterior cruciate ligament injuries in team handball: A systematic video analysis. The American Journal of Sports Medicine, 32(4), 1002-1012. doi:10.1177/0363546503261724
Polman, R.C.J. & O’Donoghue, P.G. (2007) Deceleration movements performed during FA Premier League soccer matches. Journal of Sports Science & Medicine, 18(11), 6-11.
Reilly, T., Williams, A. M., Nevill, A., & Franks, A. (2000). A multidisciplinary approach to talent identification in soccer. Journal of Sports Sciences, 18(9), 695-702. doi:10.1080/02640410050120078
Welch, N., Richter, C., Moran, K., & Franklyn-Miller, A. (2019). Principal component analysis of the associations between kinetic variables in cutting and jumping, and cutting performance outcome. Journal of Strength and Conditioning Research, 00, 1-8. doi:10.1519/JSC.0000000000003028
Young, W.B., James, R., Montgomery, I. (2002). Is muscle power related to running speed with changes of direction? The Journal of Sports Medicine and Physical Fitness, 42(3), 282-288.