Abstract
d/Objectives:Exercise-induced fatigue is a fundamental component of running performance and training, yet it is also implicated in altered movement mechanics and in- creased injury risk. While numerous studies have examined fatigue-related biomechanical changes during running, findings remain fragmented across biomechanical domains and fatigue modalities. The purpose of this systematic review was to synthesize contemporary evidence on the effects of fatigue on lower-limb biomechanics during running and to inter- pret the potential injury relevance of these adaptations.Methods:A systematic literature search was conducted in PubMed, Scopus, and Web of Science for original empirical studies published between January 2010 and December 2025. Eligible studies involved human par- ticipants performing running or running-related tasks, applied an explicit fatigue protocol, and reported quantitative lower-limb biomechanical outcomes. Study selection followed PRISMA 2020 guidelines. Data extraction included participant characteristics, fatigue protocols, biomechanical measures, instrumentation, and key findings. Methodological quality was assessed using the Cochrane Risk of Bias 2 (RoB-2) tool. Due to substantial methodological heterogeneity, findings were synthesized narratively.Results:Twenty-four studies met the inclusion criteria. Across
running-related tasks, applied an explicit fatigue protocol, and reported quantitative lower-limb biomechanical outcomes. Study selection followed PRISMA 2020 guidelines. Data extraction included participant characteristics, fatigue protocols, biomechanical measures, instrumentation, and key findings. Methodological quality was assessed using the Cochrane Risk of Bias 2 (RoB-2) tool. Due to substantial methodological heterogeneity, findings were synthesized narratively.Results:Twenty-four studies met the inclusion criteria. Across studies, fatigue consistently altered spatiotem- poral parameters, joint kinematic and kinetic variables, spring-mass behavior, impact loading, coordination variability, neuromuscular output, and inter-limb symmetry. Com- mon adaptations included increased ground contact time, reduced ankle joint power and stiffness, increased joint range of motion, elevated impact loading, and greater movement variability. These changes reflected reduced mechanical efficiency and a redistribution of mechanical load from distal to proximal joints, particularly toward the knee and hip. Similar fatigue-related biomechanical patterns were observed in both laboratory-based and real-world endurance running conditions.Conclusions:Exercise-induced fatigue produces systematic and injury-relevant alterations in lower-limb biomechanics during running. These adaptations may preserve short-term performance but create mechanical conditions associated with increased susceptibility to overuse and non-contact injuries. Integrating fatigue-aware biomechanical assessment, neuromuscular conditioning, and individualized load management strategies may help mitigate adverse fatigue-related adaptations. Life2026,16, 272 https://doi.org/10.3390/life16020272
Life2026,16, 272 2 of 28 Keywords:running biomechanics; exercise-induced fatigue; lower-limb mechanics; injury risk; spring-mass behaviour; impact loading 1. Introduction Regular involvement in sport and physical activity promotes adaptations in physical capacity and neuromuscular control, while also contributing positively to mental health and holistic development [1,2]. Despite its simplicity, running imposes substantial repetitive mechanical loads on the lower extremities, requiring efficient neuromuscular coordination, elastic energy storage, and precise joint control to maintain performance and minimize injury risk [3,4]. Fatigue, an inevitable consequence of prolonged or intense running, has been recognized as a critical factor influencing movement mechanics and injury suscep- tibility. Understanding how fatigue alters lower-limb biomechanics is therefore essential for advancing injury prevention strategies, optimizing training design, and improving performance sustainability. Fatigue is a multifactorial phenomenon encompassing neuromuscular, metabolic, and central components, all of which can influence movement execution. In the context of running, fatigue has been shown to affect force production, coordination, and motor control, leading to altered movement strategies aimed at maintaining task performance [5]. These compensatory adaptations, while potentially beneficial in the short term, may si- multaneously increase mechanical stress on musculoskeletal structures. Consequently, fatigue has been implicated as a contributing factor in both overuse injuries, such as stress fractures and tendinopathies, and acute non-contact injuries [6]. Biomechanical research over the past two decades has increasingly focused on identifying fatigue-induced changes in running mechanics. Experimental studies have reported fatigue-related alterations in spatiotemporal parameters, including prolonged ground contact time and modified stride characteristics, suggesting reduced neuromuscular efficiency and altered force application strategies [7,8]. Joint-level analyses further indicate that fatigue affects kinematics and kinetics across the ankle, knee, and hip, often resulting in reduced ankle power and stiffness and increased reliance on proximal joints to sustain locomotion [9,10]. Such proximal load redistribution has important implications for injury risk, particularly at the knee and hip. Spring-mass behaviour has emerged as a key conceptual framework for understanding fatigue-related mechanical adaptations during running. Several studies have demonstrated reductions in leg and vertical stiffness under fatigued conditions, reflecting diminished elastic energy storage and return [11,12]. Reduced stiffness may compromise shock atten- uation capacity,
proximal load redistribution has important implications for injury risk, particularly at the knee and hip. Spring-mass behaviour has emerged as a key conceptual framework for understanding fatigue-related mechanical adaptations during running. Several studies have demonstrated reductions in leg and vertical stiffness under fatigued conditions, reflecting diminished elastic energy storage and return [11,12]. Reduced stiffness may compromise shock atten- uation capacity, thereby increasing impact transmission to passive tissues such as bone and cartilage. Indeed, fatigue-induced increases in impact loading variables, including vertical loading rate and tibial acceleration, have been reported in both laboratory-based protocols and real-world endurance events [13,14]. In addition to joint mechanics and impact loading, fatigue has been shown to influence coordination variability and inter-limb symmetry. Increased coordination variability at the trunk–pelvis–hip complex and altered motor variability structure have been observed following fatigue, particularly in novice runners [15,16]. While movement variability is a normal feature of adaptive motor control, excessive or poorly organized variability under fatigue may reflect compromised neuro- muscular regulation and reduced movement stability. Similarly, fatigue-related increases in inter-limb asymmetry have been reported, indicating uneven load distribution that may predispose runners to unilateral injury development [17]. Despite extensive research on fatigue-related biomechanical adaptations in running, substantial heterogeneity exists in fatigue protocols, participant characteristics, running https://doi.org/10.3390/life16020272
Life2026,16, 272 3 of 28 environments, and biomechanical outcome measures. Fatigue has been induced using di- verse modalities, from short-duration sprint tasks to prolonged enduranceefforts—eliciting distinct physiological and mechanical responses that limit statistical comparability. Con- sequently, a narrative synthesis was adopted to integrate findings across biomechanical domains while preserving contextual and mechanistic interpretation where meta-analysis is inappropriate. Nevertheless, the growing body of research on fatigue-related running biomechanics remains fragmented. Studies vary widely in fatigue protocols, participant characteristics, running environments, biomechanical outcome measures, and verification of fatigue. More- over, while individual studies provide valuable insights, no consensus has yet emerged regarding the consistency, direction, and injury relevance of fatigue-induced biomechanical changes across different contexts. Importantly, systematic reviews that focus exclusively on synthesizing original experimental evidence while deliberately excluding secondary analyses such as meta-analyses and bibliometric studies remain relatively limited in the running biomechanics literature. Exercise-induced fatigue is a multifactorial construct encompassing interacting central, peripheral, neuromuscular, and metabolic mechanisms. Central fatigue reflects reductions in neural drive originating from the central nervous system, whereas peripheral fatigue involves impairments in excitation-contraction coupling, muscle contractile capacity, and local energy availability. Metabolic fatigue is characterized by the accumulation of metabo- lites such as hydrogen ions, inorganic phosphate, and lactate, as well as substrate depletion during prolonged exercise, while neuromuscular fatigue reflects altered motor unit re- cruitment, synchronization, and force–time characteristics. The included studies targeted these mechanisms to varying degrees depending on fatigue modality: sprint- and task- based protocols predominantly elicited metabolic and neuromuscular fatigue; prolonged endurance protocols emphasized metabolic depletion and muscle damage; and repeated or high-intensity protocols incorporated combined central and peripheral contributions. This framework provides a physiological context for interpreting the heterogeneous biomechan- ical adaptations observed under fatigue. Therefore, the purpose of this systematic review was to synthesize original empir- ical studies published between 2010 and 2025 that examined the effects of fatigue on lower-limb biomechanics during running. Specifically, this review aimed to (i) identify consistent fatigue-induced biomechanical adaptations across spatiotemporal, kinematic, kinetic, stiffness, impact, and coordination domains; (ii) evaluate the consistency of these adaptations across study designs and fatigue modalities; and (iii) interpret
review was to synthesize original empir- ical studies published between 2010 and 2025 that examined the effects of fatigue on lower-limb biomechanics during running. Specifically, this review aimed to (i) identify consistent fatigue-induced biomechanical adaptations across spatiotemporal, kinematic, kinetic, stiffness, impact, and coordination domains; (ii) evaluate the consistency of these adaptations across study designs and fatigue modalities; and (iii) interpret their potential relevance to injury-related mechanical loading. By providing an integrated synthesis of contemporary evidence, this review seeks to enhance understanding of fatigue-related biomechanical mechanisms and inform future research, training, and injury prevention strategies. Accordingly, the research question of this systematic review was framed using the PICO framework, where the population comprised, human participants engaged in running or running-related tasks across varying ages and training levels. The exposure of interest was exercise-induced fatigue, examined through running-, sprint-, endurance-, or task-based fatigue protocols, with comparisons made against non-fatigued or pre-fatigue conditions. Outcomes focused on quantitative lower-limb biomechanical measures, includ- ing spatiotemporal parameters, joint kinematics and kinetics, stiffness, impact loading, coordination variability, inter-limb asymmetry, and neuromuscular mechanical indicators. https://doi.org/10.3390/life16020272
Life2026,16, 272 4 of 28 2. Materials and Methods 2.1. Study Selection Procedures All records retrieved from the database search were imported into a reference manage- ment software, and duplicate records were removed before screening. Study selection was conducted in two stages. First, titles and abstracts were independently screened to exclude clearly irrelevant studies, such as those not involving running, not involving fatigue, or not reporting biomechanical outcomes. Second, full-text articles of potentially eligible studies were assessed against predefined inclusion and exclusion criteria. Studies were included if they involved human participants performing running or running-related tasks, employed an explicit fatigue protocol, and reported quantitative biomechanical outcomes of the lower limb. Systematic reviews, meta-analyses, bibliometric studies, non-running studies, and studies without pre-post fatigue biomechanical comparisons were excluded. Discrepancies during study selection were resolved through discussion, consistent with established sys- tematic review methodology [18]. The complete selection process is summarized using a PRISMA 2020 flow diagram (Figure). Figure 1.PRISMA 2020 flow diagram of the study selection process. All included studies involved healthy participants without diagnosed neurological disorders or acute musculoskeletal injuries; no studies explicitly examined clinical pop- ulations or runners with active injury, which limits generalizability to rehabilitation or pathological cohorts. 2.2. Literature Search: Administration and Update A systematic literature search was conducted to identify studies examining the effects of fatigue on lower-limb biomechanics during running. The search strategy was developed https://doi.org/10.3390/life16020272
Life2026,16, 272 5 of 28 and reported in accordance with the PRISMA 2020 guidelines [19] and followed established recommendations for transparent reporting of electronic search strategies in systematic reviews [20]. Searches were implemented across three electronic databases, PubMed, Scopus, and Web of Science, selected for their comprehensive coverage of biomechanics, sports science, and kinesiology research. Search terms were constructed using combi- nations of keywords and Boolean operators related to running (“running,” “treadmill,” “overground running”), fatigue (“fatigue,” “exercise-induced fatigue,” “running-induced fatigue”), and biomechanics (“biomechanics,” “kinematics,” “kinetics,” “stiffness,” “im- pact loading,” “ground reaction forces”). The complete Boolean search strategy used in PubMed was as follows: (“running” OR “distance running” OR “treadmill running” OR “overground running” OR “sprint running”) AND (“fatigue” OR “exercise-induced fatigue” OR “running-induced fatigue” OR “neuromuscular fatigue”) AND (“biomechanics” OR “kinematics” OR “kinetics” OR “joint mechanics” OR “stiffness” OR “ground reaction force” OR “impact loading” OR “spring-mass” OR “movement variability”). The search was limited to studies published in English between January 2010 and December 2025 to capture contemporary biomechanical methodologies. Reference lists of eligible studies and relevant reviews were manually screened to identify additional studies not retrieved through database searching. The final search update was performed before manuscript submission to ensure inclusion of the most recent evidence (Table). Table 1.Inclusion and Exclusion Criteria for Study Selection. Domain Inclusion Criteria Exclusion Criteria Study design Original empirical research, including experimental, quasi-experimental, observational, and field-based biomechanical studies Systematic reviews, meta-analyses, scoping reviews, bibliometric analyses, narrative reviews, editorials, commentaries Publication period Studies published between January 2010 and December 2025 Studies published before 2010 Population Human participants engaged in running or running-related tasks (recreational, trained, elite, youth, or clinical subgroups) Animal studies; non-running populations (e.g., cycling-only, walking-only, resistance-training-only studies) Age group Youth, adolescent, and adult participants Studies exclusively involving children with pathological gait unrelated to fatigue Fatigue exposure Studies that explicitly induced or quantified fatigue, including running-induced fatigue, sprint-induced fatigue, prolonged running, or task-induced fatigue with relevance to running biomechanics Studies without a defined fatigue protocol or without pre- vs. post-fatigue biomechanical comparison Primary outcome focus Lower-limb biomechanics, including kinematics, kinetics, stiffness, impact loading, coordination,
participants Studies exclusively involving children with pathological gait unrelated to fatigue Fatigue exposure Studies that explicitly induced or quantified fatigue, including running-induced fatigue, sprint-induced fatigue, prolonged running, or task-induced fatigue with relevance to running biomechanics Studies without a defined fatigue protocol or without pre- vs. post-fatigue biomechanical comparison Primary outcome focus Lower-limb biomechanics, including kinematics, kinetics, stiffness, impact loading, coordination, variability, asymmetry, or neuromuscular mechanical outcomes Studies reporting only physiological (e.g., VO2max), metabolic, perceptual, or psychological outcomes without biomechanical measures Biomechanical measures Quantitative biomechanical data derived from motion capture, force plates, instrumented treadmills, IMUs, accelerometers, pressure sensors, or validated musculoskeletal models Qualitative assessments, self-report measures, or clinical scores without biomechanical quantification Movement context Running performed on treadmill, overground, track, field, or simulated competition settings Non-running movement contexts (e.g., cycling, swimming, resistance exercise) without a running component https://doi.org/10.3390/life16020272
Life2026,16, 272 6 of 28 Table 1.Cont. Domain Inclusion Criteria Exclusion Criteria Transfer tasks Studies assessing transfer effects of running-induced fatigue on related biomechanical tasks (e.g., countermovement jump, landing, balance tests) Task-based fatigue studies unrelated to running (e.g., upper-limb fatigue only) Outcome relevance Outcomes relevant to functional morphology, movement mechanics, performance adaptation, or injury-related mechanical loading Studies focusing solely on performance time or success without biomechanical explanation Instrumentation quality Use of validated biomechanical instrumentation with clearly described measurement protocols Use of non-validated devices or insufficient description of biomechanical methods Language Articles published in English Non-English publications Accessibility Full-text articles available Abstract-only publications with insufficient methodological detail 2.3. Data Extraction Data extraction was performed using a standardized extraction form designed specif- ically for biomechanics research. Extracted information included author and year of publication, study design, participant characteristics (sample size, sex, training status), fa- tigue protocol characteristics, biomechanical outcome domains, measurement instruments, and key findings related to fatigue-induced biomechanical changes. Particular emphasis was placed on extracting details of fatigue exposure and biomechanical measurement techniques to allow methodological comparison across studies. When required information was unclear or incomplete, the original article was carefully re-examined to minimize extraction errors. This approach follows best practice recommendations for systematic reviews in movement science and biomechanics [18,21,22]. 2.4. Methodological Quality of the Included Studies The methodological quality and risk of bias of the included studies were assessed using the Cochrane Risk of Bias 2 (RoB-2) tool, adapted for experimental biomechanics and kinesiology research [23]. Although the RoB-2 tool was originally developed for random- ized controlled trials, it was pragmatically adapted in this review to evaluate within-subject experimental designs, with emphasis on measurement validity, protocol standardization, and selective reporting. The following domains were evaluated: bias arising from the randomization process, deviations from intended interventions (fatigue protocol adher- ence), missing outcome data, measurement of outcomes, and selective reporting. As most included studies employed non-randomized or within-subject experimental designs, par- ticular attention was given to protocol standardization and outcome measurement validity. Each study was categorized as having low risk of bias, some concerns, or high risk of bias. The RoB-2
randomization process, deviations from intended interventions (fatigue protocol adher- ence), missing outcome data, measurement of outcomes, and selective reporting. As most included studies employed non-randomized or within-subject experimental designs, par- ticular attention was given to protocol standardization and outcome measurement validity. Each study was categorized as having low risk of bias, some concerns, or high risk of bias. The RoB-2 tool was adapted because its domain-based framework aligns well with controlled experimental and within-subject biomechanics designs, where protocol stan- dardization and objective outcome measurement are central. Although ROBINS-I was considered, it is primarily suited for observational clinical studies with complex con- founding structures and was therefore less appropriate for tightly controlled laboratory fatigue experiments. This assessment informed the interpretation of findings but did not serve as an exclu- sion criterion, in line with PRISMA recommendations. Although the RoB-2 tool was originally developed for randomized controlled trials, it was applied in the present review with contextual adaptation due to the predominance of experimental, within-subject, and repeated-measures designs in biomechanics research. https://doi.org/10.3390/life16020272
Life2026,16, 272 7 of 28 Several RoB-2 domains, particularly outcome measurement, missing data, and selective reporting, are directly applicable to fatigue biomechanics studies regardless of randomiza- tion. The randomization domain was interpreted with caution, acknowledging that many included studies employed controlled laboratory fatigue protocols rather than allocation- based group comparisons. Alternative tools designed for non-randomized intervention studies (e.g., ROBINS-I) were considered; however, they were deemed less appropriate given the acute, mechanistic nature of the fatigue protocols and the absence of exposure- based group comparisons. This pragmatic approach aligns with prior systematic reviews in sports biomechanics that adapt RoB-2 for experimental and within-subject designs to ensure consistent and transparent methodological appraisal. 2.5. Summary Measures Due to heterogeneity in fatigue protocols, biomechanical outcome measures, and reporting metrics, standardized quantitative summary measures such as pooled effect sizes were not calculated. However, synthesis extended beyond simple vote counting. Where available, the magnitude and direction of biomechanical changes were qualitatively integrated into the narrative synthesis, including reported percentage changes, relative shifts in joint contribution, changes in stiffness magnitude, and alterations in force time characteristics. This approach emphasizes the mechanical significance of fatigue-related adaptations rather than relying solely on the frequency of reported findings and is consistent with the Synthesis Without Meta-analysis (SWiM) reporting recommendations [24]. 2.6. Synthesis of Results A narrative synthesis approach was employed to integrate findings across studies. Re- sults were synthesized according to major biomechanical domains, including spatiotempo- ral parameters, joint kinematics, joint kinetics, stiffness and spring-mass behaviour, impact loading, coordination and variability, inter-limb asymmetry, and balance-related measures. This domain-based synthesis enabled the identification of common fatigue-related biome- chanical patterns while accounting for methodological and outcome heterogeneity across studies. The synthesis process involved grouping studies according to fatigue modality, running environment, and biomechanical outcome domain, followed by structured com- parison of directional trends and consistency of fatigue-related changes across studies. Patterns were identified within and across biomechanical domains (e.g., spatiotemporal parameters, joint kinetics, stiffness, and coordination), while discrepancies were interpreted in relation to differences in fatigue intensity, participant characteristics, and measurement techniques. This approach followed established methodological guidance for narrative synthesis in
Description
This systematic review synthesizes evidence on the effects of fatigue on lower-limb biomechanics during running.