Ankle sprains are one of the most common sports injuries, accounting for 10%–20% of all sports-related injuries (Fong et al., 2007) and up to 70%–80% among college students with sports experience (Doherty et al., 2014). In the Netherlands, approximately 440,000 ankle sprains occur annually (Kemler et al., 2015), while in the United Kingdom, they constitute 3%–5% of all emergency department visits, resulting in 1–1.5 million cases per year (Gribble et al., 2016b). Acute ankle sprains can lead to repeated injuries and the development of chronic ankle instability (CAI), with a prevalence of about 20%–30% (Konradsen et al., 2002; Herzog et al., 2019). CAI is characterized by pain, instability, recurrent injuries, and persistent dysfunction (Gribble, 2019), significantly impacting an individual’s physical activity levels (Hubbard-Turner and Turner, 2015).

Landing from a height is a common scenario leading to ankle sprains (Doherty et al., 2014; Ardakani et al., 2019). During landing, the foot and ankle complex absorb the impact force from the ground, which can be 2–5 times the body weight (Xu et al., 2024b; Xu et al., 2023). This force is primarily transmitted through the medial aspect of the ankle, may cause sudden and substantial inversion of the ankle joint, which can lead to ankle sprains (Koshino et al., 2017). Larger ankle inversion angles and angular velocities during landing are associated with an increased potential for ankle sprains (Xu et al., 2024a; Zhang et al., 2024). Individuals with CAI have greater ankle inversion angles and angular velocities during landing compared to those without CAI (Simpson et al., 2022; Terrier et al., 2014). Excessive ankle inversion increases the distance between the talus and fibula, stretching the ligaments connecting these bones (Fong et al., 2012). When the ligament is stretched beyond its maximum bearing capacity, it can lead to ligament tears (Medina McKeon and Hoch, 2019).

CAI, a neurophysiological disorder characterized by maladaptive neuroplastic changes in the central nervous system (CNS), may increase potential injury under dual-task conditions. Individuals with CAI often exhibit reduced activation of the dorsal anterior cingulate cortex (Shen et al., 2022), a critical region for integrating cognitive resources (Bush et al., 2000). This reduction in cognitive resources can impair motor performance and elevate injury risk in environments requiring additional cognitive demands, such as dual-task conditions (Rosen et al., 2021; Choi et al., 2023). For example, a volleyball player with CAI aiming to execute a powerful smash must jump as high as possible and extend their upper limb. This constitutes a motor task. Simultaneously, they must consider the optimal landing spot for the ball based on the opposing defender’s position and condition, representing a cognitive task. Together, these actions embody a dual-task condition. Individuals with CAI, who have a limited total capacity of potential cognitive resources, experience reduced allocation of these resources to both cognitive and motor tasks. Consequently, their performance on either task may suffer, potentially leading to tactical errors or unintentional injuries.

There is ongoing controversy regarding the performance of individuals with and without CAI during dual-task conditions, as well as the potential impact of dual-task paradigms on injury risk in individuals with CAI. Some researchers report an increase in injury potential among individuals with FAI when transitioning from single-task to dual-task conditions, attributing this to impaired feedforward and feedback mechanisms of motor control within the CNS (Tavakoli et al., 2016). Conversely, others have observed enhanced postural stability among CAI individuals under dual-task conditions, which they attribute to increased conscious control over body movement due to fear of anticipated pain or reinjury (Shiravi et al., 2017). Moreover, it remains uncertain whether CAI individuals are more susceptible to the effects of dual-task paradigms compared to those without CAI. Some studies have indicated that athletes with FAI exhibit poorer postural stability than healthy controls under dual-task conditions, potentially increasing their injury risk (Rahnama et al., 2010). However, other studies have reported no differences in postural stability between CAI and non-CAI individuals under dual-task conditions (Choi et al., 2023).

Investigating the effects of dual-task paradigm on the injury potential among individuals with CAI may enhancing our understanding on whether the maladaptation of CNS affect the ankle sprain recurrence, and even the tactical arrangements of when and how long the players with CAI would be in the game. Therefore, we hypothesized that: 1) compared to individuals without CAI, those with CAI have higher injury potential, reflected by greater ankle inversion angle and angular velocity. 2) compared to single-task conditions, the injury potential increased among individuals with and without CAI under dual-task conditions.

The Shapiro-Wilk test indicated that all the dependent variables were normally distributed (P > 0.05). Significant group-by-condition interactions were detected in the ankle inversion angle (P = 0.04, η ² _p = 0.012) and ankle inversion angular velocity (P = 0.038, η ² _p = 0.114). Post hoc analysis showed that compared to single-task conditions, the ankle inversion angle (P = 0.003, d = 0.84) and ankle inversion angular velocity (P = 0.007, d = 0.91) were significantly decreased among individuals without CAI under dual-task conditions, whereas no significant differences were detected among individuals with CAI. Compared to those without CAI, the individuals with CAI had greater inversion angles under single- (P = 0.045, d = 0.65) and dual-task (P < 0.001, d = 1.13) conditions, and similarly, they had greater ankle inversion angular velocities under single- (P = 0.164, d = 0.46) and dual-task (P = 0.001, d = 1.03) conditions (Figure 4).

To our knowledge, this is the first study to determine the effects of the dual-task paradigm on the injury potential during drop-landing among individuals with and without CAI. The results supported Hypothesis 1, which predicted that individuals with CAI would have a higher injury potential compared to those without CAI, under both single-task and dual-task conditions. This was reflected by a greater ankle inversion angle and angular velocity among individuals with CAI. Conversely, Hypotheses 2 was not supported by the results. Hypothesis 2 proposed that, compared to single-task conditions, the injury potential would be higher among individuals with and without CAI under dual-task conditions, but this was not observed.

The results indicated that individuals with CAI exhibited greater ankle inversion angle and angular velocity compared to those without CAI under both conditions. This finding is supported by a previous study, which showed that individuals with CAI exhibited greater ankle inversion angle after initial contact during landing compared to copers (individuals who suffered ankle sprain but did not develop CAI) and healthy controls (Oh et al., 2024). We propose that the inability to limit excessive ankle inversion during landing is linked to dysfunction in ankle eversion muscles and lateral ankle ligaments. The ankle eversion muscles, especially the peroneal muscles, have been proved to have prolonged reaction time during sudden ankle inversion (Menacho Mde et al., 2010), as well as difficulty generating maximum ankle eversion torque in an inverted position among individuals with CAI (Dong et al., 2024). In the case of sudden ankle inversion, the injured anterior talofibular ligament is unable to limit the separation between the talus and fibula, making it difficult to minimize the ankle inversion angle and angular velocity (Rigby et al., 2015). As a result, individuals with CAI are more likely to be injured than individuals without CAI under both single- and dual-task conditions.

Contrary to Hypothesis 2, a surprising finding was that compared to single-task conditions, ankle inversion angle and angular velocity were lower under dual-task conditions among individuals without CAI. This may because participants adopted different movement strategies under dual-task conditions (McNevin and Wulf, 2002; Lacour et al., 2008). In the capacity sharing theory, when participants engage in dual-tasks, their attention shifts partly from the primary motor task to the supplementary task (in our study, a cognitive task). Consequently, cognitive resources are partially allocated to this additional task, the conscious control over body movements reduced (Lacour et al., 2008). To some extent, automatic and reflexive postural control strategies then take precedence to sustain motor performance (McNevin and Wulf, 2002; Lacour et al., 2008). This shift may result in superior motor performance compared to single-task conditions (Wulf et al., 2004; McNevin and Wulf, 2002; Vuillerme et al., 2000), avoiding the occurrence of injuries. For example, the lower ankle inversion angle and angular velocity observed in our study. A smaller ankle inversion angle indicates that the lateral ankle ligaments experience less strain due to inversion (Yıldız and Yalcın, 2013). Similarly, a lower ankle angular velocity indicates that muscles, such as the peroneal muscles, have adequate reaction time to activate and counteract excessive ankle inversion (Ashton-Miller et al., 1996), which all suggest a potential decrease in the risk of ankle sprains (Koshino et al., 2017).

In contrast to individuals without CAI, those with CAI did not show a decrease in injury potential when transitioning from single to dual-task conditions. The maladaptive neuroplastic changes at both spinal and cortical levels follows musculoskeletal injuries like CAI may be the reasons (Bruce et al., 2020), counteracting the injury potential that should be reduced under dual-task conditions. In the spinal level, the protective mechanism for protecting muscles from excessive strains after injuries, i.e., arthrogenic muscle inhibition (Norte et al., 2022), would affect the ability of voluntary muscle activation. This, in turn, may result in muscle weakness around ankle due to heightened activation of inhibitory interneurons synapsing in the motor neuron pool, thus reducing the efficiency of motoneuron recruitment by the CNS after injuries (Dong et al., 2024). Dong et al. demonstrated that arthrogenic muscle inhibition existed in peroneal muscles among individuals with CAI (Dong et al., 2024), which is the dominating muscles to prevent excessive ankle inversion (Ashton-Miller et al., 1996). The functions of the muscles may be inhibited by the protective mechanism at spinal level, leading to unchanged indicators concerning ankle inversion under dual-task conditions compared to single-task conditions among individuals with CAI. In the cortical level, numerous studies showed that the corticomotor excitability decreased in the projection areas of lower limb muscles around ankle in the M1 among individuals with CAI (Pietrosimone and Gribble, 2012; Terada et al., 2022; Nanbancha et al., 2019; Kosik et al., 2017), making them hard to activate the cortical motor neurons (Pietrosimone et al., 2012; McLeod et al., 2015), then leading to muscle weakness and failure of muscle activation (Pietrosimone et al., 2012). Activities of the secondary sensorimotor cortex and other cortical areas would increase to compensate for the declined cortical excitability in M1 to maintain motor performance (Needle et al., 2017; Bruce et al., 2020), but the cortical compensatory mechanism is vulnerable, which tends to collapse under dual-task conditions, leading to poorer motor performance and higher injury potential (Bruce et al., 2020). Similarly, the concurrent subtraction task may break the compensatory mechanisms at cortical level (Burcal et al., 2019), lead to the inability to confront ankle inversion from single-to dual-task conditions among individuals with CAI during landing.

There are three limitations to this study. First, participants were aware that the flippable platform surface of the trap-door device would flip during landing, so this was an anticipatory condition that may differ from a non-anticipatory condition when a real injury occurs. Second, the gender distribution was not uniform across the two groups in this study, which introduces a potential bias in the results due to gender imbalance. Considering that males and females utilize distinct feedforward control strategies during landing, with females typically activating their knee extensors earlier than males to mitigate the deficit in hip extensor rate tension development (Stearns-Reider and Powers, 2018; Di Giminiani et al., 2020), it is advisable for future research to maintain a balanced gender representation within subgroups to mitigate any potential confounding effects of gender on postural control outcomes. Last, this study did not include direct indicators of muscle activity and ligament status, and it is recommended that more attention be paid to neuromuscular factors in future studies to provide evidence through electromyographic measurements of muscle activity and computer simulation modeling calculations of ligament strain to better assess the potential of ankle injury.

Individuals with CAI have a reduced ability to limit ankle inversion, inferring increased susceptibility to ankle sprains. Under dual-task conditions, individuals without CAI limited their ankle inversion, while those with CAI did not, inferring a higher injury potential among those with CAI. Drop-landing, especially under dual-task conditions, poses a high risk of excessive ankle inversion for individuals with CAI.