The review, led by Joachim D’Hondt and colleagues, was conducted according to the PRISMA 2020 reporting guidelines and registered in advance on PROSPERO. The researchers searched four major databases, PubMed, Scopus, SPORTDiscus and Web of Science, identifying 6,804 records, which reduced to 4,811 unique articles after duplicates were removed. Rigorous title, abstract and full-text screening left just ten studies that met the inclusion criteria: original, peer-reviewed investigations of lower inter-limb asymmetry and sprinting performance in healthy, injury-free sprint athletes. Methodological quality was assessed with a modified Downs and Black Quality Index Tool, and the certainty of the evidence was graded using the GRADE framework. The studies, published between 2013 and 2025, came from Europe, North America, Oceania and Asia, and together covered 684 participants, including sixteen world-class sprinters, eight elite sprinters and 138 highly trained athletes.

Inter-limb asymmetry is not a single phenomenon but a family of them. The review distinguishes functional asymmetries, such as differences in strength or jump performance between legs; morphological asymmetries, such as differences in limb length, joint width or muscle cross-sectional area; kinematic asymmetries, involving discrepancies in joint angles, step length or contact time; and kinetic asymmetries, meaning imbalances in ground reaction forces or impulse production. Each type was measured with different tools across the ten studies, from single-leg countermovement jumps and magnetic resonance imaging to textile electromyography embedded in shorts and force measurements during actual sprinting. Complicating matters further, the studies used at least five different equations to calculate asymmetry, including the symmetry angle, percentage differences between superior and inferior limbs, fluctuating asymmetry indices and composite scores.

The headline finding is stark in its simplicity: in general, only limited associations were observed between any of these asymmetry types and sprinting performance. Prvulović and colleagues found no significant link between explosive strength asymmetry, measured with a single-leg countermovement jump, and mean velocity in a 100-metre sprint. Tottori and colleagues reported no significant associations between asymmetry in the cross-sectional area of the psoas major, quadriceps femoris or hamstrings and curve-sprinting time, with the single exception of psoas major asymmetry, which showed a small negative association with cross-directional sprint time differences. Nagahara and Gleadhill found no significant relationships between kinetic asymmetry metrics such as braking and propulsive impulse and maximal sprinting velocity over 60 metres.

Yet the picture is not uniformly null, and the exceptions are scientifically revealing. Gołaś and colleagues, studying eight elite female sprinters with textile EMG sensors, found weak-to-moderate positive associations between sprinting time and EMG asymmetry in the quadriceps, hamstrings and gluteal muscles, meaning greater asymmetry accompanied slower times. Bissas and colleagues reported that in world-class male sprinters, 100-metre time was strongly negatively associated with foot vertical velocity pre-touchdown asymmetry, while in world-class females, shank angle touchdown asymmetry was positively associated with sprint time, a striking sex-specific pattern. Exell and colleagues even found that net ankle work asymmetry and maximum vertical force asymmetry were positively associated with mean 60-metre velocity, suggesting that in some athletes, asymmetry and speed coexist, or that the dominant limb compensates for the weaker one during propulsive phases.

Perhaps the most famous data point in this debate comes from analyses of Usain Bolt himself. Previous biomechanical investigations showed that the fastest man in history ran with pronounced asymmetries: his right leg produced approximately 13 percent greater peak force, while his left leg recorded ground-contact times roughly 14 percent longer, alongside notable step-length discrepancies. If perfect symmetry were a prerequisite for world-record sprinting, Bolt’s mechanics would have made it impossible. The review’s authors point to computer simulation studies suggesting a plausible mechanism: athletes may adopt compensation strategies in which the dominant limb exerts greater force during propulsive phases to offset the weaker limb, preserving overall output despite the imbalance.

The contrast with team-sport research is equally instructive. Earlier work, including a meta-analysis by Fox and colleagues, reported a small but significant negative association between lower-limb asymmetry and sprinting performance, with correlations around 0.20. But that evidence base drew overwhelmingly from unilateral team sports such as soccer, where eight of nine studies involved players whose repetitive kicking and cutting patterns naturally create larger asymmetries. In one striking example, single-leg countermovement jump asymmetry in English Premier League academy players showed strong positive correlations with 5, 10 and 20-metre sprint times, and asymmetry magnitudes in such cohorts have reached 18 percent. Sprint athletes, by contrast, tend to display much smaller asymmetries, often in the low single digits, which may simply fall below any threshold at which performance would be affected.

The review also delivers a methodological caution that should reshape how future studies are designed. The certainty of evidence across all outcomes was rated as very low, reflecting methodological limitations, imprecision and the observational nature of the studies. Only three of the ten studies reported reliability data for their asymmetry measures, a serious gap given that asymmetry is a ratio metric highly sensitive to measurement error in either limb. The authors also argue against composite asymmetry scores, which aggregate different body regions and metrics into a single number; such scores can conflate large asymmetries in a few variables with small asymmetries across many, obscuring meaningful patterns. Because asymmetry is known to be task-, metric- and segment-specific, assessing each type independently is considered far more valid and informative.

For coaches and athletes, the practical message is one of cautious reassurance. The evidence synthesized here does not support the assertion that inter-limb asymmetry is associated with reduced sprinting performance, and the authors conclude that reducing asymmetry does not necessarily need to be a central focus of training when the goal is speed. Small fluctuations in asymmetry over time, as shown in the one longitudinal study included, likely reflect normal neuromuscular variability rather than mechanical inefficiency. That said, asymmetry reduction may still be worthwhile for other reasons, such as injury prevention, and targeted strengthening of the weaker limb has been shown to increase its capacity and reduce side-to-side differences. If practitioners do choose to address asymmetry, the evidence suggests they should do so with task-specific, metric-specific and muscle-specific assessments rather than blanket correction programs.

What remains genuinely unresolved is the question of cause and effect. With nine of the ten studies using cross-sectional designs, it is impossible to say whether asymmetry shapes sprint performance, whether sprinting shapes asymmetry, or whether both simply reflect each athlete’s unique neuromuscular signature. Exell and colleagues observed that two athletes with comparable kinetic asymmetries produced markedly different step velocities, hinting that sensitivity to asymmetry varies from person to person, with some athletes compensating effectively and others not. The review’s authors call for standardized asymmetry calculations, robust longitudinal designs, and the establishment of task-, metric- and muscle-specific thresholds that account for individual responders and non-responders. Until then, the sprinter’s lopsided stride, once viewed as a flaw to be engineered away, may deserve to be seen for what the evidence now suggests it often is: a harmless quirk of a body built for speed.

Subject of Research: The relationship between inter-limb asymmetry and sprinting performance in sprint athletes

Article Title: The Relationship Between Inter-limb Asymmetry and Sprinting Performance in Sprint Athletes: A Systematic Review

Article References: D’Hondt, J., Chapelle, L., Van Handenhoven, J., Stalmans, J., & Aerenhouts, D. (2026). The Relationship Between Inter-limb Asymmetry and Sprinting Performance in Sprint Athletes: A Systematic Review. Sports Medicine – Open, 12(1), Article 146. https://doi.org/10.1186/s40798-026-01082-1

Image Credits: AI Generated

DOI: 10.1186/s40798-026-01082-1

Keywords: inter-limb asymmetry, sprinting, biomechanics, sports medicine, systematic review, kinematics, kinetics, muscle morphology, athletic performance, sprint athletes, neuromuscular, training