Are You Missing a Step When Coaching Change of Directions? The Importance of the Penultimate Foot Contact for Performance and Injury Risk Mitigation

Directional changes are some of the most exciting and decisive actions performed in multidirectional sports, often performed to deceive and evade opponents or change location on the pitch or court. Despite their importance for performance, directional changes are actions associated with injury inciting events such as knee ligament (ACL), hamstring, groin, or ankle injury. Much of the attention has been placed on examining technical, neuromuscular, and biomechanical characteristics of the main foot plant which is primarily responsible for executing and deflecting the centre of mass during directional changes. However, we argue that practitioners are missing and overlooking an important step when coaching and examining performance and injury risk determinants during change of direction.

In this blog, we will highlight the importance of the penultimate foot contact for successful and effective change of direction and discuss the implications for performance, injury risk, and screening. This will be based on our penultimate foot contact review we published in 2019 (Dos’Santos, Thomas, Comfort, & Jones, 2019); however, we are now in position to share some new insights based on recent research we have conducted.

What is the Penultimate Foot Contact and What is its Purpose?

Directional changes are a multistep action (Andrews, McLeod, Ward, & Howard, 1977) and the penultimate foot contact (PFC – or penultimate step) plays a major role in facilitating such actions. The PFC is defined as “the 2nd to last foot contact with the ground prior to moving into a new intended direction” (Dos’Santos et al., 2019)(Figure 1) and serves two primary functions (dependent on the COD scenario, angle of COD, approach velocity, and physical capacity for that athlete):

1. Positional / preparatory step – to facilitate an effective whole-body position for effective push-off during the main COD foot contact (i.e., final foot contact [FFC] – main execution phase).
2. Braking step – to reduce momentum prior to push-off during the FFC (typically for CODs of sharper angles >60˚, but dependent on the COD scenario, approach velocity, angle of COD, and athlete physical capacity).

Why is the Penultimate Foot Contact Important?

Athletes during COD typically initiate the directional change one or more steps prior to the main COD foot contact; this is known as anticipatory postural adjustments. These postural adjustments typically include kinematic changes in foot placement, trunk lean and rotation (and pelvis rotation), and head rotation. By typically pre-rotating the step or steps prior to the main push-off (FFC) (Figure 2), this helps re-orientate the whole-body centre of mass (COM) towards the intended direction of travel, thus reducing the redirection demands of the FFC, facilitating faster performance, and making it easier to deflect the centre of mass (David, Mundt, Komnik, & Potthast, 2018).

For sharper directional changes (i.e., ≥ 60˚ cuts and 180˚ pivots), the PFC also plays an important role as a preparatory step by positioning the whole-body COM for effective push-off during the FFC. For example, in Figure 3 for a 180° COD, you can see the athlete goes through rapid hip, knee, and ankle dorsi-flexion to lower the COM, and they perform this in a rotated position to re-orientate the COM towards the intended direction of travel, again reducing the redirection demands during the FFC. This then puts the athlete in a favourable position for effective push-off during the FFC, where the PFC now is an optimal position to facilitate effective reacceleration.

When performing COD actions, athletes will typically reduce their velocity (i.e., momentum) prior to changing direction. The magnitude of the reduction in momentum will be influenced by a variety of factors, including the athlete’s approach velocity, physical capacity, intended angle of COD, sports specific scenario, and environmental factors (i.e., shoe-surface interface, frictional properties etc.). As approach velocity and / or angle increases, athletes will need to reduce their momentum over the PFC and potentially over a series of steps prior to the FFC, in order to perform the intended angle of COD, which we describe as an angle-velocity trade-off (Figure 4) and we have discussed in this review in 2018 (Dos’Santos, Thomas, Comfort, & Jones, 2018). Based on the literature, it appears that for CODs ≤ 45°, PFC braking requirements and forces are limited, and velocity maintenance is key (however the PFC is still important for effective body positioning). Conversely, for CODs >60°, the PFC plays an important role in braking and undoubtedly preliminary deceleration is needed. It is worth noting that with greater approach velocities, distances, and angles, preliminary deceleration will occur over a number of foot contacts, with deceleration distances of 1-7m commonly observed.

Results from our research show that PFC dominant braking strategies (i.e., maximising and emphasising horizontal braking force / impulse) could be one strategy to help improve COD performance (Dos’Santos, McBurnie, Thomas, Comfort, & Jones, 2020; Dos’Santos, Thomas, Jones, & Comfort, 2017; Dos’Santos, Thomas, McBurnie, Comfort, & Jones, 2021a; Graham-Smith, Atkinson, Barlow, & Jones, 2009; Jones, Thomas, Dos’Santos, McMahon, & Graham-Smith, 2017; McBurnie, Dos’ Santos, & Jones, 2021) while reducing knee joint loading during the FFC and potential injury-risk (Dos’Santos et al., 2021a; Graham-Smith et al., 2009; McBurnie et al., 2021). We have also some preliminary evidence that the antepenultimate foot contact (3^rd to last foot contact) is also important for facilitating braking and deceleration for fast entry velocity pre-planned 180° CODs (Dos’ Santos, Thomas, & Jones, 2021); however, we will expand on this in a future blog. From a performance aspect, by braking earlier during the PFC (and potentially steps prior) we:

1. Increase braking impulse which leads to a reduction in horizontal momentum of the COM (i.e., impulse-momentum relationship).
2. This then allows more effective weight acceptance and preparation for the drive-off phase of the directional change, and can allow the FFC to emphasise propulsion, rather than braking (as the FFC often has a dual role of braking and propulsion), also resulting in a shorter ground contact time (a key determinant of faster performance).
3. Greater PFC braking forces are associated with faster 70°, 90˚ and 180˚ COD performance (Dos’Santos et al., 2017; Dos’Santos et al., 2021a; Graham-Smith et al., 2009; McBurnie et al., 2021).

From an injury risk perspective, PFC dominant braking strategies may help alleviate knee joint loads during the FFC (Dos’Santos et al., 2019; Dos’Santos et al., 2021a; Graham-Smith et al., 2009). Knee joint loads have the potential to strain the ACL, and when high enough, can result in rupture. Emphasising braking during the PFC is a safer strategy compared to the FFC because:

1. PFC braking is typically performed in the sagittal plane where we can utilise the strong hip and knee musculature and the GRF vector is more aligned with knee joint (though athletes should ensure strong lower-limb frontal plane alignment).
2. The knee goes through greater knee flexion range of motion (PFC ~100-120° vs. ~FFC 20-60°), which means greater angular displacement. Thus, based on the work-energy principle, increased work equates to a greater reduction in kinetic energy and decrease in velocity (change in velocity).
3. We reduce FFC GRF and subsequent knee joint loads in FFC – the limb which gets injured during COD actions – while reducing the braking requirements of the FFC.
4. Crucially, ACL injuries occur ≤ 50ms which provides limited / insufficient time for postural adjustments (neuromuscular feed-forward mechanism). Thus, reducing momentum prior to FFC is critical for reducing knee joint loads and potential ACL strain.

We have also shown in three 6-week change of direction technique modification intervention studies, that teaching athletes how to decelerate effectively, and adopt PFC braking strategies can improve cutting (Dos’Santos, McBurnie, Comfort, & Jones, 2019; Dos’Santos, Thomas, Comfort, & Jones, 2021b) and pivoting performance (Dos’Santos, Thomas, McBurnie, Comfort, & Jones, 2021b) and associated biomechanics while reducing potential knee joint loads  (Dos’Santos, Thomas, Comfort, & Jones, 2021a). For further information on PFC technical guidelines and braking and COD technique modification training programmes, please read these published articles, or see our braking strategy training resource linked below.

We feel that deceleration training is a critical component of teaching athletes how to fully utilise the PFC for effective change of directions. In our braking strategy training resource (linked below), we highlight that the PFC is not only critical for facilitating effective direction changes during forward running, but also a key preparatory step during lateral shuffles, oblique running, and backpedalling. We demonstrate the variety of positions, movement planes, and intensities, that can be utilised when developing an athlete’s braking strategy during field-based training. This method of training can be an isolated training session, or if limited for time, can be easily integrated into the field-based warms-up of sports’ technical/tactical sessions.

ACCESS FREE BRAKING STRATEGY TRAINING RESOURCE HERE

Penultimate Foot Contact Technical Guidelines

Technical guidelines for coaching the PFC are presented in our review article we have published in SCJ (Dos’Santos et al., 2019). and Hopefully, coaches can begin to understand the importance of the PFC as a preparatory and / or braking step.

Briefly, key technical characteristics for braking during PFC involve:

• Creating a large COM to centre of pressure (COP) distance, via anterior placement of the PFC in front of the body, and a backward lean of the trunk to shift the COM posteriorly. This emphasizes a posteriorly directed force vector and maximises horizontal braking force to reduce momentum (impulse = change in momentum) prior to the push-off phase.
• Simultaneous, hip, knee (up to ~100˚) and ankle dorsi-flexion occurs, to support the loading in the sagittal plane (facilitates longer braking force application, thus impulse – range of motion movement principle) and lower the COM for better stability. This occurs over a ground contact time of 0.15-0.40 s (note: this is influenced by entry velocity and angle of COD).
• Practitioners should be aware of knee alignment during the PFC and reinforce strong frontal plane lower-limb alignment.
• The head and trunk should be directed forward, or some athletes may choose to rotate slightly towards the intended direction of travel to reduce the redirection demands during the FFC, for effective realignment into the new intended direction, and permit earlier visual scanning of the situation.

Braking Strategy Variance

It is also worth noting that athletes may adopt variance in braking strategies. The video below illustrates the differences in braking strategies adopted by athletes. For example, in the case of a 180° COD, some athletes adopt a bilateral / dual support braking strategy, whereby the foot involved with PFC remains in contact with the ground during the braking phase of the FFC. This strategy facilitates and distributes the loading across two-foot contacts, thus maximising braking impulse over the PFC due to the longer GCT, and potentially lowering forces during the FFC. In addition, this approach loads up the inside leg, and the PFC is now in an optimal position for acceleration once the FFC is complete.

Conversely, illustrated by the female athlete and bottom video, athletes may adopt a clear flight phase between the PFC and FFC during a 180° turn, and adopt a unilateral / single support braking strategy, whereby the athlete will rotate their whole body during this flight phase in order to align themselves into the intended direction. The absence of leaving the PFC or inside leg in contact with the ground increases the loading during the FFC, and typically prolongs the ground contact time, thus potentially sub-optimal for performance and injury risk. It is also worth acknowledging the amount of preparation time will influence the braking strategies adopted by athletes. For example, with longer preparation times (pre-planned or early identification of a stimuli), athletes will likely adopt braking over a greater number of foot contacts, whereby the ante-penultimate might be a key braking step and the PFC can be more pre-rotated to facilitate early reorientation and easier deflection. Conversely, with shorter preparation times (unplanned COD and / or late reaction to stimuli), more abrupt braking is likely to occur with a greater reliance on the PFC. Therefore, as part of an agility development framework, it would be key to develop a range of different braking solutions and strategies for athletes.

We like to use the example of landing from a jump to help explain the importance of the PFC during COD. It is safer for an athlete to land bilaterally when landing from a jump, because the potential mechanical loading can be distributed more evenly between both limbs, thus substantially reducing the loading to each limb. Conversely, when landing unilaterally, all the mechanical loading must be tolerated and braking forces must be produced and supported on limb, thus increasing the absolute loading to that limb. This example can be applied during aggressive and sharp directional changes whereby the absolute loading to the limbs can be reduced by adopting a bilateral turning strategy. However, we appreciate that athletes must possess flexible movement strategies and a range of movement solutions to achieve the movement outcomes they require in sport. Therefore, athletes will likely require the capacity to be able to display both bilateral and unilateral turning strategies; however, practitioners should be cognizant that the bilateral turning strategy appears to be both the fastest and safer strategy.

Screening Penultimate Foot Contact Movement Quality

Practitioners should be aware of knee alignment during the PFC when screening and coaching COD technique. The video below shows an athlete displaying sub-optimal lower-limb alignment during a cutting task utilising the CMAS. In this example, it is worth highlighting that sub-optimal movement quality and neuromuscular control was exhibited during a pre-planned, low-entry velocity task, in a non-fatigued state. These poor mechanics are likely to be amplified in a fatigued, unplanned COD, and situations with greater approach velocities, which will likely exacerbate the potential knee joint loads to this athlete. In this scenario, this a red-flag and we immediately highlighted this potential issue to the head of S&C and sports medicine. Consequently, in addition to screening and coaching the main execution foot contact during directional changes, it is imperative practitioners evaluate the PFC and potentially steps prior during COD to optimise performance and mitigate injury risk. This can be done during the CMAS using the frontal plane camera video footage and / or during linear horizontal deceleration task and pivoting tasks with a high-speed camera positioned in the frontal plane.

Summary

Hopefully in the blog we have convinced you why the PFC is an important aspect of COD performance and injury risk mitigation. In summary, we have 3 key take-home messages and practical applications to support you in your delivery of COD and agility training and screening:

1. COD is a ‘multistep action’ – PFC should not be ignored or overlooked, and can be considered a ‘preparatory  step’ and / or braking step to facilitate effective COD.
2. Adopting a PFC dominant strategy may lead to faster performance and reduced knee joint loading in FFC and can be considered a strategy to mediate the performance-injury conflict that is present during COD.
3. Practitioners should be aware of braking strategy variance and PFC lower-limb alignment when coaching and screening COD mechanics.

References

Andrews, J. R., McLeod, W. D., Ward, T., & Howard, K. (1977). The cutting mechanism. The American journal of sports medicine, 5(3), 111-121.

David, S., Mundt, M., Komnik, I., & Potthast, W. (2018). Understanding cutting maneuvers–The mechanical consequence of preparatory strategies and foot strike pattern. Human Movement Science, 62, 202-210.

Dos’ Santos, T., Thomas, C., & Jones, P. A. (2021). How Early Should You Brake During A 180° Turn? A Kinetic Comparison Of The Antepenultimate, Penultimate, And Final Foot Contacts During A 505 Change Of Direction Speed Test. Journal of sports sciences, 39(4), 395-405.

Dos’Santos, T., McBurnie, A., Comfort, P., & Jones, P. A. (2019). The Effects of Six-Weeks Change of Direction Speed and Technique Modification Training on Cutting Performance and Movement Quality in Male Youth Soccer Players. Sports, 7(9), 205.

Dos’Santos, T., McBurnie, A., Thomas, C., Comfort, P., & Jones, P. A. (2020). Biomechanical determinants of the modified and traditional 505 change of direction speed test. The Journal of Strength & Conditioning Research, 34(5), 1285-1296.

Dos’Santos, T., Thomas, C., Comfort, P., & Jones, P. A. (2021a). Biomechanical effects of a 6-week change-of-direction technique modification intervention on anterior cruciate ligament injury risk. The Journal of Strength & Conditioning Research, 35(8), 2133-2144.

Dos’Santos, T., Thomas, C., Comfort, P., & Jones, P. A. (2021b). Biomechanical Effects of a 6-Week Change of Direction Speed and Technique Modification Intervention: Implications for Change of Direction Side step Performance. Journal of strength and conditioning research, Published Ahead of Print.

Dos’Santos, T., Thomas, C., Jones, P. A., & Comfort, P. (2017). Mechanical determinants of faster change of direction speed performance in male athletes. The Journal of Strength & Conditioning Research, 31, 696-705.

Dos’Santos, T., Thomas, C., Comfort, P., & Jones, P. A. (2018). The effect of angle and velocity on change of direction biomechanics: an angle-velocity trade-off. Sports medicine, 48(10), 2235-2253.

Dos’Santos, T., Thomas, C., Comfort, P., & Jones, P. A. (2019). The Role of the Penultimate Foot Contact During Change of Direction: Implications on Performance and Risk of Injury. Strength & Conditioning Journal, 41(1), 87-104.

Dos’Santos, T., Thomas, C., McBurnie, A., Comfort, P., & Jones, P. A. (2021a). Biomechanical determinants of performance and injury risk during cutting: a performance-injury conflict? Sports medicine, 51, 1983–1998.

Dos’Santos, T., Thomas, C., McBurnie, A., Comfort, P., & Jones, P. A. (2021b). Change of direction speed and technique modification training improves 180° turning performance, kinetics, and kinematics. Sports, 9(6), 73.

Graham-Smith, P., Atkinson, L., Barlow, R., & Jones, P. (2009). Braking characteristics and load distribution in 180 degree turns. Paper presented at the Proceedings of the 5th annual UKSCA conference.

Jones, P. A., Thomas, C., Dos’Santos, T., McMahon, J., & Graham-Smith, P. (2017). The Role of Eccentric Strength in 180° Turns in Female Soccer Players. Sports, 5(2), 42. Retrieved from http://www.mdpi.com/2075-4663/5/2/42

McBurnie, A., Dos’ Santos, T., & Jones, P. A. (2021). Biomechanical Associates of Performance and Knee Joint Loads During an 70-90° Cutting Maneuver in Sub-Elite Soccer Players. Journal of strength and conditioning research, 35(11), 3190-3198.