Kinesiophobia is an emerging concept as it relates to SRC recovery. While there are several other modifiers of recovery from a SRC, our study suggests that kinesiophobia may also play a prognostic role in terms of days until clinical recovery for collegiate athletes. The primary aim of this study was to determine the influence of acute kinesiophobia on time until clinical recovery in collegiate athletes diagnosed with SRC. Our results supported our hypothesis that athletes who reported levels of kinesiophobia above a previously established clinical cutoff of ≥ 37, as measured by the TSK within 72 h of SRC, took longer to achieve clinical recovery. In fact, the H-TSK group achieved symptom resolution approximately 2.5 days later compared with those in the L-TSK group. Interestingly, TSK scores were also both the strongest predictor of and more strongly correlated with days to clinical recovery than other commonly accepted modifiers of recovery such as acute symptom burden. We also observed that a premorbid diagnosis of anxiety/depression may influence TSK reporting behavior.

Our findings are in alignment with related research that suggests kinesiophobia may associate with SRC [15, 17, 32]. Specifically, Reinking et al. reported that kinesiophobia was moderately correlated with clinical reaction time (r = 0.50, p = 0.01) in that as kinesiophobia increased, reaction time slowed in adolescent athletes. Additionally, at their RTP assessment, 28% of the injured adolescent athletes in that study continued to report high levels of kinesiophobia [15]. This, however, was not a significant difference compared with the 24% of controls who also reported high levels at the same timepoint. Anderson et al. [17] evaluated the influence of fear of re-injury, as measured by the TSK, on certain recovery outcomes such as the ImPACT battery, a symptom inventory, the Vestibular/Ocular Motor Screen, and days to recovery in high school athletes. While they defined a higher score on the TSK as an indication of greater fear of re-injury, it is important to clarify that the TSK total score is not solely related to fear of re-injury. Prior research has utilized confirmatory factor analyses of the TSK and suggests that the most common factors associated with the TSK include activity avoidance, pathological somatic focus, and harm, with only one study suggesting fear of re-injury as one of four factors [29]. Nevertheless, Anderson et al. concluded that high school athletes in the high fear group reported statistically significant increases in total, cognitive–migraine–fatigue, and affective symptoms [17]. Participants in the high fear group were also observed to be five times more likely to have Vestibular Ocular/Motor Screen values indicative of vestibular/ocular dysfunction when compared with those in the low fear group [17]. However, both groups had similar recovery times.

In contrast to Anderson et al. [17], our results suggest that collegiate athletes with high levels of acute kinesiophobia took longer to achieve clinical recovery than those with low levels. A potential rationale for this discrepancy is timing of the TSK administration and sample size. Anderson and colleagues administered the TSK on average 5 days after the injury, while we administered it within 3 days [17]. In addition, Anderson et al. reported total recovery time (i.e., total number of days from the date of injury to medical clearance, inclusive of asymptomatic physical and cognitive activity), rather than just the clinical recovery timepoint used in this study, exclusive of asymptomatic physical activity [17].

A strength of the current study is its relatively large sample size as compared with related studies [15, 17, 32]. While we cannot conclude from our study the definitive role of kinesiophobia in recovery from SRC, it is plausible that it is a modifier of time to clinical recovery in collegiate athletes. This is especially reasonable given the moderate correlation and statistically and clinically significant median differences that we observed. From a clinical standpoint, a difference in 2.5 days may be the difference between an athlete participating in a competition or not after completing a return to sport protocol. Similarly, additional interventions following concussion including prompt removal from sport [44] and subsymptom threshold exercise [36] have reported comparable improvements in recovery time. While more work surrounding the prevention of delayed recovery after concussion is warranted, clinicians should account for psychological variables such as kinesiophobia, specifically during the acute phase of injury. Doing so may provide clinicians with multiple points of intervention to ultimately afford their patient the opportunity to have a more typical recovery.

While an intervention for kinesiophobia in the context of concussion has yet to be fully identified, it may be as simple as providing the injured athlete opportunities to gain confidence in their physical abilities through physical activity and conversations with sport psychologists. Exposure therapy is one of the most effective ways to treat phobia-related disorders [33]. For athletes with concussion, this may be done with exposure to prescribed physical activity. Prescribed physical activity has been shown to reduce kinesiophobia in variable populations [26]. Smulligan et al. demonstrated that greater reductions in TSK scores were moderately correlated with higher daily step counts and exercise frequency among children with persisting symptoms (≥ 28 days) [34]. Given these findings, we hypothesize that reductions in kinesiophobia may also be a partial explanation of why subsymptom threshold aerobic exercise following concussion reduces recovery time. As such, it is important for clinicians to consider the implications of prescribing complete physical rest after an “invisible” injury, such as concussion, and the implications it may have on athlete psychology. By prescribing complete rest, athletes may internalize the prescription by viewing physical activity as bad, resulting in a fear of physical activity, especially given our finding that a premorbid diagnosis of anxiety/depression can influence TSK reporting behavior. While adhering to physical rest, athletes may then catastrophize their lingering symptoms, which may lead to misattribution and kinesiophobia as evidenced by the fear avoidance model [35]. As the breadth of concussion literature supports an active as opposed to passive approach to rehabilitation [36, 37], the evaluation of kinesiophobia acutely after injury may be more relevant than ever.

Our findings suggest that kinesiophobia, as measured by the TSK, may be a modifier of recovery from concussion, and even more so than commonly accepted modifiers of recovery such as acute symptom burden and anxiety/depression. Although a prior meta-analysis (unrelated to concussion) found strong associations between pain-related fear and disability (i.e., occupational, social, or recreational), this relationship was not moderated by pain characteristics such as duration and intensity [38]. In the context of concussion, these pain characteristics can be contextualized to include deficits such as symptom severity and duration. We observed that kinesiophobia can influence recovery time separately from symptom severity after concussion. Another intriguing finding of prior work was the existence of a strong relationship between pain-related fear and disability among people experiencing acute pain [38]. The authors concluded that future work should evaluate how reducing acute pain-related fear may impede progression to chronic pain [38]. In the context of those findings, in combination with the findings of our study, kinesiophobia may be an important and measurable signal for developing prolonged symptomology. If clinicians do not evaluate kinesiophobia during the acute phase of injury, they may omit an opportunity to intervene and facilitate a more typical recovery from concussion. It is important to note that a “quicker” recovery is not always a “better” recovery; however, we feel that accounting for a more holistic view of an athlete after concussion may result in the identification of multiple opportunities for intervention as opposed to solely characterization. The identification of one or more therapeutic targets may assist athletes to achieve a more typical and safe return to sport. The latter is particularly important as evidence supports a relationship between return to sport after concussion and an increased risk of subsequent musculoskeletal injury [39, 40].

A systematic review [39] of 13 articles explored this relationship and concluded that 4 studies showed an increased risk of subsequent lower extremity injury within 90 days following a diagnosed concussion. In the same review, six studies demonstrated an elevated risk of subsequent injury within 1 year of concussion [39]. The underlying mechanism(s) for the relationship between concussion and lower extremity injury has/have yet to be determined. Previous literature examining ACL injury has suggested that kinesiophobia can negatively influence biomechanics and therefore risk of injury [12, 41]. Specific to concussion, Thompson et al. concluded that there was a greater proportion of athletes who reported kinesiophobia levels above 37 at their return to play assessment who were subsequently diagnosed with a time-loss musculoskeletal injury within 180 days of returning to play compared with those who scored below 37 [32]. Moreover, it is plausible that decreased reaction time, as a function of kinesiophobia [15], could increase an athlete’s risk of sustaining a subsequent injury [32], especially given findings that reaction time deficits can persist up to 59 days post-injury [42]. This evidence remains mixed, however, with one study concluding that clinical reaction time was not a predictor of subsequent musculoskeletal injury in collegiate athletes [43]. This interpretation provides an initial framework for establishing kinesiophobia not only as a modifier of recovery, but also as a potential mechanism for influencing risk of subsequent musculoskeletal injury following return to sport after a SRC.

Our study had limitations. First, the TSK clinical cutoff scores used in this study were established in a population of patients with low back pain; thus it is important to note that the TSK has not been validated specifically in collegiate athletes with concussion. However, we also treated the TSK as a continuous variable in our analyses and continued to observe an association between the TSK score and symptom resolution time. Additionally, despite not being designed for concussion, the TSK is agnostic to a specific injury. For example, many questions ask about “My pain… or “My medical condition… or “My accident…” etc. We did not alter the verbiage of the TSK to reflect a different injury, which we believe supports the original measurement properties. It is imperative that future studies assess the testing properties of the TSK to support or to establish new clinical cutoffs specifically in athletes diagnosed with SRC. Additionally, our participants self-reported their medical history, which may be subject to recall bias. It is also plausible that some athletes may have received specific interventions such as medication or physical therapy that may have contributed to symptom status. This was not recorded in this study. Lastly, all participants’ symptoms resolved within a relatively typical time frame [4]. Despite this, those in the H-TSK group still took longer to achieve clinical recovery.