On Wednesday, April 21st, Jo Verschueren will defend his PhD Thesis. The interaction of fatigue and adaptability with lower extremity functional performance tests. A wonderful collaboration between our group and the MFYS Laboratory of Romain Meeussen. His defence is public and can be joined through … http://www.youtube.com/VUBeadlesOffice (Wednesday April 21st. 11.45 - 13.00).
Summary
Sports participation and physical activity have numerous health benefits. Physical activity has been promoted as a medicine because it has the potential to decrease the risk for cardiovascular disease and improve wellbeing. However, physical activity also includes a risk of getting injured. In an athletic population, lower extremity injuries are most prevalent. Besides the immediate health and athletic impairments, a lower extremity injury can also affect the long term athletic career developments and increases the risk for subsequent lower extremity injuries. In an attempt to optimize athletic health and performance, preventing lower extremity injury became a focal point in sports medicine research. Injury prevention includes all effort undertaken to prevent injuries. Within this perspective, functional performance tests are utilized by clinicians and researchers to compile injury risk profiles, monitor rehabilitation progress and inform a criteria-based and safe return to sport decision-making approach. Functional performance tests are measurements that evaluate an athlete’s current functional ability. Although literature documents a significant association between some functional performance test outcomes and increased injury risk, these tests should be interpreted in a more complex, athlete-centred approach to sports injuries. When selecting the most appropriate functional performance tests, clinicians consider both the athlete’s injury history as the current health status and clinical context. Functional performance tests outcomes are then used to inform interventions customized to the observed impairments. However, in a comprehensive athlete-centred approach, functional performance tests should also approximate the athletic context. This highlights the need to continuously develop functional performance tests and evaluate different interactions that arise within the athletic context. Interestingly, the current functional performance test approach neglects the relevance of fatigue and adaptability as apparent in an athletic context. Adaptability is defined as the athlete’s ability to modify responses under a broad spectrum of conditions.
Fatigue is a multidimensional phenomenon and includes both central and peripheral fatigue mechanisms as well as physical and mental fatigue constructs. From an athletic perspective, fatigue is often defined as an exercise-induced impairment of performance. Fatigue is hypothesized to affect injury risk and can impair functional and athletic performance outcomes. Furthermore, adaptability was recently put forward as an important driver in injury prevention. Understanding the interaction of fatigue with functional performance tests and associated injury risk could aid clinicians in making a well-informed choice in injury risk profiling and return to play strategies. Additionally, integrating adaptability could complement the current functional performance test approach given its relevance in the athletic context. The goal of the present dissertation was to gain more insight in how fatigue interacts with functional performance tests, injury risk and adaptability.
In our first study (chapter two) we provide a systematic literature review to identify the existing body of evidence on the interaction between acute physical fatigue and prospectively determined injury risk factors for lower extremity injuries. Forty-three studies documented the effect of acute fatigue on modifiable risk factors for lower extremity injuries, but only eight included the exact outcome measures as documented in the original research paper to be associated with an increased lower extremity injury risk. The body of evidence is scarce and of low quality, with no evidence that acute fatigue increases the non-contact ACL, ITBFS or generic lower extremity injury risk profiles. Only limited evidence was found for the statement that acute fatigue negatively affects the lateral ankle sprain, a patellofemoral pain syndrome or hamstring injury risk profiles.
In chapter three, we describe the systematic development and test protocol of the reactive balance test. The reactive balance test is a neurocognitive single-leg balance test that integrates environmental perception, decision making and reaction time. The outcomes are accuracy and visuomotor response time. The athlete is placed on a Y-balance test kit and is instructed to extinguish the appropriate LED lights as fast as possible. LED lights are placed on 80% of the maximal reach distance in each axis as scored in the Y-balance test. A randomized visuomotor task indicates which LED light to extinguish. To allow an objective assessment of accuracy, the reactive balance test is recorded and balance errors and decisions errors are retrospectively evaluated. Visuomotor time is extracted using the Fitlight training system©. The reactive balance test is a functional performance test that allows clinicians to score an athlete’s adaptability.
Consequently, we performed two randomized cross-over studies to explore the effect of mental fatigue (chapter four) and acute physical fatigue (chapter five) with four functional performance tests, including three traditional functional performance tests, the Y-balance test, the countermovement jump test, the single-leg hop test and the neurocognitive reactive balance test.
The results presented in chapter four illustrate that mental fatigue does not affect outcomes of the included traditional functional performance tests, but does impair accuracy in the reactive balance test. Following a 90 minute 100% incongruent Stroop task, participants accuracy significantly decreased in the reactive balance test. Mental fatigue can negatively affect adaptability.
The results presented in chapter five illustrate that acute physical fatigue can cause divergent fatigue responses in functional performance test outcomes. While the countermovement jump and Y balance test performance remained unaffected, single-leg hop distance significantly decreased following a 30-second all-out sprint effort (Modified Wingate procedure). Additionally, this is the first study documenting the effect of acute physical fatigue on a neurocognitive functional performance test. Acute physical fatigue also impairs accuracy in the reactive balance test. Clinicians should be aware of these divergent neurocognitive and functional impairments caused by acute fatigue to allow a well-informed selection of specific functional performance tests. Acute physical fatigue can also negatively affect adaptability.
When summarizing all our findings, we can conclude that acute physical fatigue can affect injury risk. However, the popular hypothesis that fatigue increases injury risk can’t be generally accepted and more high-quality research is needed because the body of evidence is scarce and of low quality. This thesis highlights that acute physical fatigue interacts with functional performance tests, but comprises large intra- and interindividual differences. Clinicians should be aware of this interaction and a paradigm shift is needed towards evaluating individual fatigue responses. Moreover, neurocognitive functional performance test can complement the current use of functional performance tests. Accuracy, as evaluated by the reactive balance test, was the only outcome measure that was impaired by both acute physical fatigue and mental fatigue. The single-leg hop for distance test was only impaired following acute physical fatigue and seems suited to detect functional impairments caused by acute physical fatigue. The Countermovement Jump test and Y-balance test were unaffected by both acute physical fatigue and mental fatigue, and appear most robust to detect maximal functional performance.
For future research, more teamwork is needed to merge insights from fatigue and injury prevention experts. Additionally, evaluating individual fatigue responses might expose patterns that are masked in current data monitoring strategies and group-level analyses. Prospective research is needed to explore the added value of neurocognitive functional performance tests in injury risk profiling or return to sport decision making.
Works published out of this thesis
Verschueren JO, Tassignon B, Proost M, Teugels A, J VANC, Roelands B, et al. Does Mental Fatigue Negatively Affect Outcomes of Functional Performance Tests? Medicine & Science in Sports & Exercise. 2020;52(9):2002-10.
Verschueren J, Tassignon B, De Pauw K, Proost M, Teugels A, Van Cutsem J, et al. Does Acute Fatigue Negatively Affect Intrinsic Risk Factors of the Lower Extremity Injury Risk Profile? A Systematic and Critical Review. Sports Med. 2020;50(4):767-84.
Verschueren J, Tassignon B, Pluym B, Van Cutsem J, Verhagen E, Meeusen R. Bringing context to balance: development of a reactive balance test within the injury prevention and return to sport domain. Arch Physiother. 2019;9:6.
Verschueren J, Tassignon B, Verhagen E, Meeusen R. The interaction of acute physical fatigue with three traditional functional performance tests and the reactive balance test. Physical Therapy in Sport. 2021;49:188-95.