Introduction
Horizontal decelerations are movements during which the horizontal momentum of the body is reduced; for example, to slow down after a sprint or to prepare for a cutting or pivoting manoeuvre. During multidirectional team sports, horizontal decelerations form a substantial part of the total number of activities performed (Akenhead et al., 2013; Dalen et al., 2016; Harper et al., 2019; Vigh-Larsen et al., 2018). Not surprisingly then, decelerations have important implications for both performance and injury risk in multidirectional team sports. In soccer, for example, horizontal decelerations are one of the most important movements preceding goals (Martínez-Hernández et al., 2023) and a high frequency of decelerations during games is positively linked to match outcome (Rhodes et al., 2021). From an injury perspective, horizontal decelerations are a major contributor to common injuries, including hamstring strain injuries (Gronwald et al., 2022; Kerin et al., 2022)and anterior cruciate ligament (ACL) injuries (Cochrane et al., 2007; Della Villa et al., 2020; Johnston et al., 2018), across various multidirectional sports.
Given the strong links between horizontal decelerations and performance and injury, a thorough understanding of the demands of deceleration movements is warranted. In a recent musculoskeletal modelling study (Verheul et al., 2024) we have sought to clarify the key requirements of decelerations from an in-depth biomechanical perspective. One important aim of this work was to take a step towards informing appropriate deceleration-specific training prescription, which is yet suboptimal (Marvin et al., 2024). To achieve this, we provided a comprehensive description of forces acting at the different levels of the musculoskeletal system – i.e., at a whole-body level, a structural level, and a tissue level (Verheul et al., 2020). In this blog I will outline the most important forces experienced during the initial step of decelerating from sprinting across different levels of the musculoskeletal system. I will then discuss the influence of various confounding factors on deceleration forces and make several suggestions for training implications.
The phases of a deceleration step
The ground-contact phase of a horizontal-deceleration step can be broken down into three phases, during which the musculoskeletal demands are distinct (see Figure 1 and the accompanying video (Verheul et al., 2024)). The first phase describes the initial 0-30% of ground contact, during which the foot strikes the ground. This phase is primarily characterised by the presence of major external ground reaction forces leading to high contact forces on the lower-limb joints. The second phase describes the time between 30-80% of stance and is marked by high internal ankle plantarflexion and knee extension joint moments, leading to eccentric force requirements on the quadriceps and soleus muscles. The third and final phase describes the last 20% of ground contact and is characterised by large internal knee extension moments and eccentric quadriceps (especially the rectus femoris) force requirements. This distinction between the three phases of decelerations can help us understand the combination of forces acting on the body at different levels.
Forces acting at different levels of the musculoskeletal system
Whole-body forces
The ground reaction force is a commonly used metric to assess overall musculoskeletal loading and refers to the external force experienced by the body (i.e., the whole-body level) during a collision with the ground. During decelerations the peak vertical ground reaction force can be up to 6-8 times the body weight of an athlete. To put this in perspective, this is ~1.5-3 times higher than the external force experienced during accelerated or high-speed running (Verheul et al., 2021, 2019) (Figure 2). These high forces are even more pronounced in the horizontal anteroposterior (i.e., forward-backward) direction, which are typically ~4 times higher compared to other tasks. Note that the horizontal ground reaction force is necessary to slow down the horizontal centre of mass velocity of the body. It is important to note that the peak ground reaction forces, both in vertical and horizontal direction, typically occur within the first 30-50 ms after the foot strikes the ground (Figure 1 – phase 1). This leads to high loading rates (i.e., the rate at which the force increases) which puts increased demands on the muscles to contract rapidly (see below section on muscle forces).
Structural forces
Although the relationship between ground reaction forces and internal forces is not linear, the high external forces experienced during decelerations subsequently lead to high internal forces on the joints (i.e., the structural level). Immediately after the foot strikes the ground (Figure 1 – phase 1) the ankle, knee, and hip are exposed to considerable joint contact forces (also called ‘bone-on-bone’ forces). Especially for the ankle, the contact forces are very high at ~25 times the body weight of the athlete, which is ~2-2.5 times greater than what is typical for running at a constant speed. These high ankle forces help explain why athletes who engage in multidirectional sports are exposed to a greater risk of sustaining ankle injuries (Fong et al., 2007). Similar to the ankle, the knee’s joint contact forces in the axial direction (i.e., along the axis of the shank) – but not the shear forces – are also substantial at ~13 times body weight. These high compressive knee forces predispose athletes to an elevated risk of sustaining knee injuries, such as ACL rupture. Hence, it is not surprising that decelerations have been found to be a major risk factor for ACL injuries during multidirectional sports (see, e.g., Della Villa et al., 2020 or Lucarno et al., 2021).
In addition to high contact forces, the joints experience substantial moments during each phase of decelerating. The internal hip extension (Figure 1 – phase 1), knee extension and ankle plantarflexion (Figure 1 – phase 2), and knee extension (Figure 1 – phase 3) moments are particularly large. These large moments are essential for stabilising the joints and prevent collapse in the presence of the high external ground reaction forces and are produced through a concerted coordination of the lower-limb muscles. Therefore, I will now highlight the key muscle forces that are required for decelerating.
Tissue forces
To cope with the whole-body and structural forces described above, considerable demands are placed on the lower-limb muscles and tendons. These are summarised for twelve key muscles in Table 1. When examining the required muscle forces (i.e., forces at a tissue level), there are two key characteristics to consider: first, the magnitude of the force produced by a muscle during the movement, and second, the kinematics of the muscle during contraction (either lengthening or shortening). Especially high peak forces produced whilst the muscle is lengthening (i.e., eccentric muscle actions), are known to lead to muscle damage and fatigue. This can result in reductions in performance (Lakomy and Haydon, 2004) and put athletes at an increased risk of injury (Jaspers et al., 2018).
The most important muscle group for effectively attenuating the external and internal forces during decelerations are the quadriceps. The rectus femoris and vasti muscles contract eccentrically throughout the entirety of the stance phase and primarily function to stabilise the knee joint by producing a large knee extension moment. The required quadriceps forces are not only considerable in magnitude (up to ~5.5 times the athlete’s body weight) but also occur at the highest (eccentric/lengthening) velocity of all the muscles in the lower limbs. This combination of eccentric contraction, high force requirements, and high muscle lengthening velocities, make the quadriceps muscles most prone to fatigue, muscle damage and injury, and declines in muscle coordination ability and performance.
Besides the quadriceps, several other muscle groups are required to produce substantial forces – both in magnitude and whilst lengthening. The gluteus muscles contract eccentrically and produce forces up to ~6.5 times body weight. This is required to counter rapid hip flexion due to the trunk moving forward because of the high horizontal ground reaction forces. Furthermore, two shank muscles – the tibialis anterior and soleus – produce their highest forces (~4 and ~3 times body weight, respectively) eccentrically at high lengthening velocities. Nevertheless, in contrast to the quadriceps, these muscles only contract eccentrically for shorter bursts of time during the stance phase. Hence, although the glutes, soleus, and tibialis anterior are at risk of fatigue and muscle damage because of repeatedly decelerating, performance declines and injury risk are likely to be lower compared to the quadriceps.
A muscle group of particular interest for multidirectional sports are the hamstrings, which are well known be one of the major injury locations. Recent evidence has suggested possible links between deceleration movements and hamstring injuries (Gronwald et al., 2022; Kerin et al., 2022). Interestingly, the hamstrings do not produce considerably high and/or eccentric forces when horizontally decelerating. It should, however, be noted that the work discussed here only describes mechanical forces and does not consider the individual capacity of the muscles, which is likely to be lower for the hamstrings compared to, e.g., the vasti.
Factors affecting deceleration forces
So far, I have described the forces experienced during the first step of decelerating from a maximal sprint. However, decelerations in multidirectional sports are also commonly initiated from submaximal running speeds. Moreover, slowing down – either to a full standstill or to adequately prepare for a follow-up manoeuvre – typically takes multiple steps over which the body’s momentum gradually decreases. Hence, when we are interested in the musculoskeletal load accumulated by athletes due to decelerations, a description of a broader range of horizontal deceleration activities is necessary. This includes submaximal-speed decelerations and changes in forces over multiple steps. Although data on various (submaximal) approach speeds and multiple steps is currently unavailable, some of our preliminary work (Hitchens and Verheul, in progress) highlights several key messages.
Decelerations initiated from maximal sprinting (i.e., a 100% approach speed) impose greater vertical and horizontal ground reaction forces compared to decelerations performed from 85% and 70% approach speeds (Figure 3). Moreover, external forces are always the highest during the first decelerative step and progressively decrease across subsequent steps. It is interesting to note that even at the third step of a deceleration from sprinting, the peak vertical ground reaction force (~3.7 times an athlete’s body weight) remains comparable to those observed in high-speed running (3-4 times body weight) and are considerably larger than to those seen in accelerative running (~2 times body weight) (see Figure 2). This highlights that the damaging and fatiguing nature of the movement likely accumulates more throughout the entirety of deceleration tasks compared to other tasks. Additionally, the decrease in peak force across steps is more pronounced in the vertical direction (13% and 11% decrease from first to second, and second to third step, respectively), compared to the horizontal direction (1% and 7% decrease from first to second, and second to third step, respectively) (Figure 3). This interaction increases the horizontal-to-vertical force ratio in the second and third step which leads to a greater deceleration intensity (i.e., the rate of slowing down of the horizontal centre of mass velocity), and thus a better deceleration performance (see below section on implications). In our ongoing work we aim to further examine the impact of changes in the external force ratio on internal forces acting on individual structures and tissues.
Implications for deceleration-specific training
Given the high forces (both external and internal) experienced by the musculoskeletal system, adequate preparation of multidirectional team-sports athletes is essential to cope with the demands of deceleration movements. Although the necessity for deceleration-specific training has been highlighted (Harper et al., 2024, 2022; Harper and Kiely, 2018; McBurnie et al., 2022), the effectiveness of current deceleration training practice remains limited, with a lack of training specificity being one of the underlying reasons (Marvin et al., 2024). This lack of specificity is, at least partially, the result of a limited understanding of the individual muscle demands when decelerating. The above-described muscle forces, an insight in muscle-specific lengthening velocities, can thus be used to inform future training interventions.
Based on the whole-body, structural, and tissue forces outlined above, several aspects should be kept in mind when prescribing deceleration-specific training interventions. First, the quadriceps are the most highly challenged muscle group during horizontal decelerations. Specifically, the quadriceps need to cope with a combination of high forces and rapid lengthening velocities. High-velocity and high-load eccentric training is thus likely to be the most effective approach to enhance deceleration ability and fatigue resistance of the quadriceps. The same approach is recommended for the gluteus, soleus, and tibialis anterior muscles. Second, joint contact forces are considerably higher during decelerations compared to other tasks (especially at the ankle). This requires an ability to safely coordinate the lower-limb muscles to stabilise the joints and effectively attenuate the induced structural forces. However, such coordinative ability is often compromised by lower-limb injuries (e.g., ACL rupture (Sinkjær and Arendt-Nielsen, 1991; Smeets et al., 2021)). Hence, during rehabilitative training after injury, high-speed decelerations should be one of the last tasks to be included prior to return-to-play and are a key movement to quantify as part of performance and return-to-play assessments. Finally, preliminary results from Hitchens and Verheul (in progress) show a greater horizontal-to-vertical ground reaction force ratio (and subsequent deceleration intensity) in the later deceleration steps. It is possible that the initiation of decelerating after, e.g. sprinting, results in a sub-optimal body position due to the transition from an anterior to a posterior lean, limiting the athlete’s ability to generate high horizontal ground reaction force during the first deceleration step. Therefore, to optimise deceleration performance, deceleration-specific training should not only focus on increasing the horizontal-to-vertical force ratio, but also on an efficient transition into the deceleration.
It is important to emphasise that the most appropriate forms of training are likely to be dependent on the sport and individual athlete. However, several excellent suggestions for deceleration-specific eccentric training methods have recently been described in a previous blog post and in the braking performance framework (Harper et al., 2024). Nevertheless, the effectiveness of such eccentric training approached with a view to enhance deceleration ability or reduce deceleration-related injury rates, largely remains to be established.
Summary
To summarise, there are several key takeaways described in this blog:
- Both external and internal forces acting on the musculoskeletal system are substantially higher during horizontal decelerations compared to other multidirectional team-sports movements.
- Muscles exposed to a combination of high forces and rapid lengthening velocities are the quadriceps, gluteus, tibialis anterior, and soleus muscles, and require specific consideration.
- Training approaches targeting enhanced deceleration performance or injury prevention may focus on these muscle groups, but the effectiveness of deceleration-specific training remains to be established.
- Sub-optimal body position during the initial deceleration step may limit an athlete’s ability to generate the required external forces, warranting a focus on efficient transition into the deceleration.
References
Akenhead, R., Hayes, P.R., Thompson, K.G., French, D., 2013. Diminutions of acceleration and deceleration output during professional football match play. J. Sci. Med. Sport 16, 556–561. https://doi.org/10.1016/j.jsams.2012.12.005
Cochrane, J.L., Lloyd, D.G., Buttfield, A., Seward, H., McGivern, J., 2007. Characteristics of anterior cruciate ligament injuries in Australian football. J. Sci. Med. Sport 10, 96–104. https://doi.org/10.1016/j.jsams.2006.05.015
Dalen, T., Jørgen, I., Gertjan, E., Havard, H.G., Ulrik, W., 2016. Player load, Acceleration, and Deceleration during 45 Competitive Matches of Elite Soccer. J. Strength Cond. Res. 30, 351–359.
Della Villa, F., Buckthorpe, M., Grassi, A., Nabiuzzi, A., Tosarelli, F., Zaffagnini, S., Della Villa, S., 2020. Systematic video analysis of ACL injuries in professional male football (soccer): injury mechanisms, situational patterns and biomechanics study on 134 consecutive cases. Br. J. Sports Med. 54, 1423–1432. https://doi.org/10.1136/bjsports-2019-101247
Fong, D.T.-P., Hong, Y., Chan, L.-K., Yung, P.S.-H., Chan, K.-M., 2007. A Systematic Review on Ankle Injury and Ankle Sprain in Sports. Sports Med. 37, 73–94. https://doi.org/10.2165/00007256-200737010-00006
Gronwald, T., Klein, C., Hoenig, T., Pietzonka, M., Bloch, H., Edouard, P., Hollander, K., 2022. Hamstring injury patterns in professional male football (soccer): a systematic video analysis of 52 cases. Br. J. Sports Med. 56, 165–171. https://doi.org/10.1136/bjsports-2021-104769
Harper, D., Cervantes, C., Dyke, M.V., Evans, M., McBurnie, A., Santos, T.D., Eriksrud, O., Cohen, D., Rhodes, D., Carling, C., Kiely, J., 2024. The Braking Performance Framework: Practical Recommendations and Guidelines to Enhance Horizontal Deceleration Ability in Multi-Directional Sports. Int. J. Strength Cond. 4. https://doi.org/10.47206/ijsc.v4i1.351
Harper, D.J., Carling, C., Kiely, J., 2019. High-Intensity Acceleration and Deceleration Demands in Elite Team Sports Competitive Match Play: A Systematic Review and Meta-Analysis of Observational Studies. Sports Med. 49, 1923–1947. https://doi.org/10.1007/s40279-019-01170-1
Harper, D.J., Kiely, J., 2018. Damaging nature of decelerations: Do we adequately prepare players? BMJ Open Sport Exerc. Med. 4, 1–3. https://doi.org/10.1136/bmjsem-2018-000379
Harper, D.J., McBurnie, A.J., Santos, T.D., Eriksrud, O., Evans, M., Cohen, D.D., Rhodes, D., Carling, C., Kiely, J., 2022. Biomechanical and Neuromuscular Performance Requirements of Horizontal Deceleration: A Review with Implications for Random Intermittent Multi-Directional Sports. Sports Med. 52, 2321–2354. https://doi.org/10.1007/s40279-022-01693-0
Hitchens, L., Verheul, J., in progress. A biomechanical comparison of deceleration performance across multiple steps and approach speeds.
Jaspers, A., Kuyvenhoven, J.P., Staes, F., Frencken, W.G.P., Helsen, W.F., Brink, M.S., 2018. Examination of the external and internal load indicators’ association with overuse injuries in professional soccer players. J. Sci. Med. Sport 21, 579–585. https://doi.org/10.1016/j.jsams.2017.10.005
Johnston, J.T., Mandelbaum, B.R., Schub, D., Rodeo, S.A., Matava, M.J., Silvers-Granelli, H.J., Cole, B.J., ElAttrache, N.S., McAdams, T.R., Brophy, R.H., 2018. Video Analysis of Anterior Cruciate Ligament Tears in Professional American Football Athletes. Am. J. Sports Med. 46, 862–868. https://doi.org/10.1177/0363546518756328
Kerin, F., Farrell, G., Tierney, P., McCarthy Persson, U., De Vito, G., Delahunt, E., 2022. Its not all about sprinting: mechanisms of acute hamstring strain injuries in professional male rugby union—a systematic visual video analysis. Br. J. Sports Med. 56, 608–615. https://doi.org/10.1136/bjsports-2021-104171
Lakomy, J., Haydon, D.T., 2004. The Effects of Enforced, Rapid Deceleration on Performance in a Multiple Sprint Test. J. Strength Cond. Res. 18, 579.
Lucarno, S., Zago, M., Buckthorpe, M., Grassi, A., Tosarelli, F., Smith, R., Della Villa, F., 2021. Systematic Video Analysis of Anterior Cruciate Ligament Injuries in Professional Female Soccer Players. Am. J. Sports Med. 49, 1794–1802. https://doi.org/10.1177/03635465211008169
Martínez-Hernández, D., Quinn, M., Jones, P., 2023. Linear advancing actions followed by deceleration and turn are the most common movements preceding goals in male professional soccer. Sci. Med. Footb. 7, 25–33. https://doi.org/10.1080/24733938.2022.2030064
Marvin, L., Read, P., McLean, B., Palmer, S., Fransen, J., 2024. Training Interventions for Improved Deceleration Ability in Adult Team-Based Field Sports Athletes: A Systematic Review and Meta-Analysis of the Literature. Int. J. Strength Cond. 4. https://doi.org/10.47206/ijsc.v4i1.313
McBurnie, A.J., Harper, D.J., Jones, P.A., Dos’Santos, T., 2022. Deceleration Training in Team Sports: Another Potential ‘Vaccine’ for Sports-Related Injury? Sports Med. 52, 1–12. https://doi.org/10.1007/s40279-021-01583-x
Rhodes, D., Valassakis, S., Bortnik, L., Eaves, R., Harper, D., Alexander, J., 2021. The Effect of High-Intensity Accelerations and Decelerations on Match Outcome of an Elite English League Two Football Team. Int. J. Environ. Res. Public. Health 18, 9913. https://doi.org/10.3390/ijerph18189913
Sinkjær, T., Arendt-Nielsen, L., 1991. Knee stability and muscle coordination in patients with anterior cruciate ligament injuries: An electromyographic approach. J. Electromyogr. Kinesiol., Ligaments and the Sensory-Motor Control of Knee Motion and Stability 1, 209–217. https://doi.org/10.1016/1050-6411(91)90036-5
Smeets, A., Willems, M., Gilson, L., Verschueren, S., Staes, F., Vandenneucker, H., Claes, S., Vanrenterghem, J., 2021. Neuromuscular and biomechanical landing alterations persist in athletes returning to sport after anterior cruciate ligament reconstruction. The Knee 33, 305–317. https://doi.org/10.1016/j.knee.2021.10.020
Verheul, J., Gregson, W., Lisboa, P.J., Vanrenterghem, J., Robinson, M.A., 2019. Whole-body biomechanical load in running-based sports: The validity of estimating ground reaction forces from segmental accelerations. J. Sci. Med. Sport 22, 716–722. https://doi.org/10.1016/j.jsams.2018.12.007
Verheul, J., Harper, D., Robinson, M.A., 2024. Forces experienced at different levels of the musculoskeletal system during horizontal decelerations. J. Sports Sci. 42, 2242–2253. https://doi.org/10.1080/02640414.2024.2428086
Verheul, J., Nedergaard, N.J., Pogson, M., Lisboa, P., Gregson, W., Vanrenterghem, J., Robinson, M.A., 2021. Biomechanical loading during running: can a two mass-spring-damper model be used to evaluate ground reaction forces for high-intensity tasks? Sports Biomech. 20, 571–582. https://doi.org/10.1080/14763141.2019.1584238
Verheul, J., Nedergaard, N.J., Vanrenterghem, J., Robinson, M.A., 2020. Measuring biomechanical loads in team sports – from lab to field. Sci. Med. Footb. 4, 246–252. https://doi.org/10.1080/24733938.2019.1709654
Vigh-Larsen, J.F., Dalgas, U., Andersen, T.B., 2018. Position-Specific Acceleration and Deceleration Profiles in Elite Youth and Senior Soccer Players. J. Strength Cond. Res. 32, 1114–1122. https://doi.org/10.1519/JSC.0000000000001918
