The research team, led by investigators at Huazhong University of Science and Technology in Wuhan, China, recruited twenty female college soccer players aged nineteen to twenty-three from two university teams. Each participant completed the Yo-Yo Intermittent Endurance Level 2 Test, a widely validated soccer-specific fatigue protocol involving repeated twenty-meter shuttle runs at progressively increasing speeds. Fatigue was confirmed when athletes reached a heart rate of at least eighty-five percent of their estimated maximum or reported a rating of fifteen or higher on the Borg six-to-twenty perceived exertion scale. All twenty participants met the fatigue criteria before post-fatigue testing began.

Researchers assessed three movement tasks before and after fatigue induction: single-leg landing from a thirty-centimeter platform, double-leg landing from the same height, and a zigzag running course with four five-meter segments and a one-hundred-degree turning angle. Surface electromyography recorded activity from twelve lower limb muscles, including the rectus femoris, vastus lateralis, vastus medialis, biceps femoris, semitendinosus, and tibialis anterior on both legs. Force plates simultaneously captured peak vertical ground reaction forces, stabilization time, and center of pressure displacement, providing a complementary kinetic picture of how fatigue altered landing mechanics.

The most robust finding emerged during double-leg landing, where normalized muscle activation dropped significantly in three key quadriceps muscles. The right vastus lateralis showed a decrease from a median of 8.58 to 7.78 percent peak amplitude, the left vastus lateralis fell from 9.45 to 8.36, and the right vastus medialis declined from 9.86 to 8.27. Critically, these three results survived false discovery rate correction, a statistical safeguard that filters out findings likely to be false positives. Every other significant change in the study remained exploratory, meaning the authors urge caution in interpreting them as definitive fatigue effects.

During single-leg landing, the picture shifted. Peak vertical ground reaction force, normalized to body weight, decreased significantly on both sides after fatigue. The left foot dropped from 2.52 to 2.34 body weights while the right fell from 2.69 to 2.40, both surviving statistical correction. Stabilization time, the duration from ground contact until force fluctuations settled within five percent of body weight, also lengthened on the left side, though this finding did not survive correction and remains tentative. The authors suggest this combination may reflect a more conservative landing strategy adopted under fatigue, where athletes deliberately soften impact forces to maintain control at the expense of explosive cushioning.

In zigzag running, a pre-fatigue asymmetry in rectus femoris activation between the left and right legs, which was statistically significant before correction, disappeared after fatigue. The researchers note this could indicate either a strategic shift toward more symmetrical muscle recruitment or simply bilateral neuromuscular fatigue dampening output on both sides. Without concurrent kinematic data capturing joint angles and moments, the team cannot determine which interpretation is correct. They also acknowledge that because zigzag running was tested last, six to eight minutes after the fatigue protocol, partial recovery may have influenced the result.

The study’s context matters. Women’s soccer participation has surged globally, reaching approximately 16.6 million organized players as of 2023, and female athletes face a substantially elevated risk of non-contact anterior cruciate ligament injuries compared to males, with soccer players sustaining four to six times the risk. Fatigue, bilateral lower limb asymmetry, and neuromuscular control deficits are recognized as key contributors. Collegiate athletes, who often train with less structured periodization than professionals, may be particularly vulnerable to fatigue-induced changes in movement strategy.

The authors are careful to frame their conclusions within the study’s limitations. The sample was drawn from only two university teams, the within-subject design lacked a non-fatigued control group, and the fixed testing sequence means task-order effects cannot be fully separated from fatigue effects. Sleep, nutrition, and menstrual cycle data were not collected. Nonetheless, the findings offer preliminary support for targeted training interventions, including unilateral stability work, quadriceps fatigue resistance, and multidirectional neuromuscular conditioning tailored to the demands of change-of-direction play.

For coaches and sports scientists, the message is that fatigue does not degrade all muscles equally or uniformly across tasks. The knee extensors appear most vulnerable during bilateral landing, while single-leg stability and cutting mechanics show different patterns of adaptation. As women’s soccer continues its rapid global expansion, understanding these task-specific neuromuscular responses may prove essential for designing injury prevention programs that keep athletes healthy deep into matches and tournaments.

Subject of Research: Effects of fatigue on lower limb neuromuscular control and landing biomechanics in female collegiate soccer players

Article Title: The impact of fatigue on lower limb neuromuscular control in female college soccer players

Article References: Xiang, T., Zhu, T., Ma, H., Mu, Z., Han, Z., Imai, K., Shen, S., Guo, Z., & Zhou, X. (2026). The impact of fatigue on lower limb neuromuscular control in female college soccer players. Frontiers in Sports and Active Living, 8, Article 1918634. https://doi.org/10.3389/fspor.2026.1918634

Image Credits: AI Generated

DOI: 10.3389/fspor.2026.1918634

Keywords: sports science, female athletes, soccer, neuromuscular control, fatigue, ACL injury, biomechanics, electromyography, impact, lower, limb, neuromuscular

The research team recruited 52 competitive players — 26 men and 26 women aged roughly 18 to 30 — from two federated Spanish clubs. All were field players, not goalkeepers, with at least three years of continuous water polo experience, training four to five days per week and competing at regional or national level. Crucially, every athlete was free of shoulder injury and pain for the six months before testing, ensuring that the measurements captured healthy, adapted shoulders rather than compromised ones. Data were collected across roughly nine months of the competitive season, following STROBE reporting guidelines and ethical approval from the European University of Madrid.

The investigators took a three-pronged approach. Functional capacity was quantified with a handheld dynamometer, measuring maximal isometric strength of the shoulder’s internal and external rotators with the arm at 90 degrees of abduction, from which they calculated the internal-to-external rotation strength ratio (IR/ER ratio) — a key index of muscle balance around the joint. Biomechanics were assessed with the PALM palpation meter, a caliper-based device that tracks the position of the scapula’s inferior angle relative to the spine both at rest and during maximal arm elevation, yielding a measure of scapular displacement. Structure was probed with ultrasound: supraspinatus tendon thickness, the rotator cuff muscle most implicated in overhead pathology, was imaged in the modified Crass position with a high-frequency linear transducer.

On the surface, the raw numbers told a familiar story. Men produced significantly greater internal rotation strength (15.94 versus 13.32 kilograms, p = 0.011) and a higher IR/ER ratio (1.27 versus 1.11, p = 0.004), the latter showing a large effect size of 0.87. Women, by contrast, exhibited markedly greater scapular displacement during arm elevation — 7.08 centimeters versus 5.85, p = 0.004, also a large effect. External rotation strength showed only a non-significant trend favoring men (p = 0.052), and supraspinatus tendon thickness was statistically indistinguishable between sexes, averaging around 0.62 centimeters in both groups. Arm dominance, whether right- or left-handed, made no difference to any measured variable.

Then came the twist. Because the male players were, on average, taller (1.77 versus 1.69 meters) and heavier (72.73 versus 67.53 kilograms) than their female counterparts, the researchers ran multiple linear regression models with sex, height, and body mass as predictors. Once body size was accounted for, sex lost its association with internal rotation strength (p = 0.331) and the IR/ER ratio (p = 0.177). In other words, the apparent strength advantage of male water polo players was largely a reflection of bigger bodies, not of maleness itself — a finding consistent with decades of evidence that absolute muscle force scales strongly with anthropometry.

Scapular displacement, however, refused to disappear. Even after adjustment for height and body mass, sex remained a significant predictor of scapular displacement (β = −0.850, p = 0.005), and the result survived Holm-Bonferroni correction for multiple comparisons (adjusted p = 0.020). This means the greater movement of the shoulder blade during arm elevation in female players is not explained by their smaller frames — it appears to be a genuine, sex-specific biomechanical characteristic of the water polo shoulder.

What might drive this difference? The authors point to a constellation of factors documented in the broader literature: women generally exhibit greater joint laxity, lower passive tissue stiffness, and distinct neuromuscular control strategies, all of which could alter how the scapula moves as the arm rises overhead. There is also a sport-specific consideration. Men and women compete under essentially identical conditions — same pool dimensions, same match duration, and balls of the same weight despite slight differences in size — meaning female players may shoulder a relatively greater mechanical load during each throw. The researchers are careful to note this hypothesis was not directly tested, but it offers a plausible framework for why scapular behavior might diverge between sexes under equal external demands.

Importantly, greater scapular displacement should not automatically be read as pathology. Scapular dyskinesis — altered movement patterns of the shoulder blade — is common in overhead athletes and has been linked to shoulder disorders, but the authors emphasize that increased displacement may equally represent a functional adaptation to the sport’s demands. Disentangling adaptation from risk factor requires longitudinal work that this cross-sectional design cannot provide. The same caution applies to the strength findings: an elevated IR/ER ratio has been associated with shoulder dysfunction in overhead athletes, but since sex was not an independent determinant of this ratio in water polo players, the authors argue that rotator cuff conditioning should be tailored to each athlete’s functional profile rather than to sex alone.

The clinical implications are tangible. Shoulder injuries account for 25 percent of all self-reported injuries and 16 percent of physiotherapist-reported injuries in water polo, making it the most frequently injured anatomical site and the source of a quarter of all lost training days. Previous research has reported shoulder injury rates nearly 2.4 times higher in female players than in males (8.09 versus 3.40 injuries per 100 participant-years), while other work found that 80 percent of the most severe injuries — those causing three or more weeks of absence — occurred in male athletes. Against this backdrop, the new findings suggest that prevention programs built around sex alone may miss the mark: strength deficits track body size, but scapular control may deserve particular attention in female players’ neuromuscular training.

The study is not without limitations, which the authors acknowledge candidly. The convenience sample of 52 athletes from two clubs limits generalizability, and the exploratory design was powered to detect only large effects. Playing position — center forward, driver, winger, or defender — was not systematically recorded, despite the very different throwing volumes these roles entail. The PALM device captures static and functional scapular position reliably, but it cannot capture the full three-dimensional kinematics of the scapula during an actual throw. And because all measurements were taken by a single unblinded examiner, some measurement bias cannot be excluded. Still, as a first sport-specific integration of strength, scapular mechanics, and tendon morphology in male and female water polo players, the study carves out a clear message: when it comes to the water polo shoulder, what separates the sexes is not raw force but the way the shoulder blade moves — a distinction that could reshape how the sport screens, trains, and protects its athletes.

Subject of Research: Sex differences in shoulder strength, scapular displacement, and supraspinatus tendon morphology in competitive water polo players

Article Title: Shoulder strength, scapular displacement, and supraspinatus morphology in male and female competitive water polo players: a cross-sectional study

Article References: del-Blanco-Muñiz, J. Á., Bermejo-Franco, A., Giménez, M.-J., Salniccia, F., Mendoza-Castejón, D., & Trinidad, A. (2026). Shoulder strength, scapular displacement, and supraspinatus morphology in male and female competitive water polo players: a cross-sectional study. Frontiers in Sports and Active Living, 8, Article 1933053. https://doi.org/10.3389/fspor.2026.1933053

Image Credits: AI Generated

DOI: 10.3389/fspor.2026.1933053

Keywords: water polo, shoulder biomechanics, scapular displacement, rotator cuff strength, sex differences, supraspinatus tendon, injury prevention, overhead athletes, handheld dynamometry, ultrasound, sports science, neuromuscular control

The stakes are far from abstract. Anterior cruciate ligament ruptures, ankle sprains, and a host of other lower-limb injuries frequently occur during landing and cutting maneuvers, and they occur disproportionately when the athlete is reacting to an unpredictable situation rather than executing a rehearsed one. Decades of research have shown that neuromuscular warm-up programs can reduce injury rates when performed consistently over months. What has remained murky is whether a single session of such a warm-up has any immediate, acute effect on movement quality, and whether embedding cognitive challenges into that warm-up, forcing athletes to perceive, decide, and react while moving, could amplify the benefit. The new study was designed to probe exactly that question with laboratory-grade measurement tools.

Eighteen team-sport athletes, five of them women, with an average age of twenty-three years, completed three different warm-up routines on separate days in a randomized three-arm crossover design. The reference intervention was the Prevent Injury and Enhance Performance program, known as PEP, a structured neuromuscular warm-up with an established evidence base in injury prevention. The two experimental variants layered cognitive load onto the same physical framework. The first, called PEP+, added exercises targeting visuomotor processing and executive functions, the mental machinery that governs attention, inhibition, and rapid decision-making. The second, PEP-SKILLCOURT, incorporated reactive agility drills using an interactive training device that lights up targets athletes must respond to, blending perception, choice, and whole-body movement under time pressure.

After each warm-up, the athletes performed jump-landing tasks on a capacitive pressure plate that recorded the forces and pressure distribution beneath their feet with high temporal resolution. Crucially, the researchers distinguished between two landing conditions. In the pre-planned condition, athletes knew in advance which foot would take the brunt of the landing. In the unplanned condition, the landing side was cued only after take-off, mimicking the real-world scenario in which a defender’s position or a teammate’s challenge forces a last-millisecond adjustment. Six trials examined the pre-planned version and sixteen the unplanned one, giving the unplanned task, the one that matters most for injury, the larger share of the statistical spotlight.

The measurement battery read like a biomechanist’s wishlist. Peak vertical ground reaction force, the single largest spike of force shooting up through the leg at touchdown, has long been scrutinized as a potential marker of injurious landing loads. Time to that peak reveals how abruptly the force arrives, since steeper loading rates are thought to stress ligaments and cartilage. Center of pressure path length traced how much the athlete wobbled, capturing postural control as the body fought to hold its balance. Time to stabilization quantified how quickly the athlete settled into a steady stance, while standing errors and decision errors recorded outright failures of control and cognition, such as landing on the wrong foot or losing balance entirely.

The analysis employed linear and generalized mixed models, a statistical framework well suited to repeated-measures designs in which each athlete serves as their own control, and the models adjusted for flight time to account for differences in jump execution. The first reassuring finding was methodological: no significant carryover effects emerged, meaning that the order in which athletes experienced the three warm-ups did not contaminate the comparisons. The dominant signal in the data, however, belonged not to the warm-ups but to the landing condition itself. Whether a landing was planned or sprung on the athlete in mid-air significantly altered peak vertical ground reaction force and center of pressure dynamics, with differences ranging from minus four to plus seventeen percent, and it significantly changed error rates as well.

Post hoc tests sharpened that picture. During unplanned landings, athletes exhibited lower peak vertical ground reaction forces yet greater fluctuations in their center of pressure, alongside significantly more errors of both the standing and decision variety. At first glance, lower landing forces might sound like good news, but the accompanying instability and error counts tell a different story: athletes were softer on touchdown precisely because they were less organized, absorbing the landing with a less controlled strategy rather than a more protective one. The findings align with a growing body of evidence that cognitive uncertainty degrades motor performance, and they suggest that the unplanned landing task successfully recreated the perceptual-motor chaos that precedes many real-world injuries.

What about the cognitive warm-ups themselves? Here the trial’s verdict was deliberately restrained. After Holm adjustment, the standard procedure for controlling false positives across multiple comparisons, no significant treatment effects or treatment-by-condition interactions survived. In plain terms, the study could not confirm that any of the three warm-ups acutely changed landing biomechanics or error rates. Yet the exploratory trends were intriguing enough to flag. Athletes who had completed the PEP+ version, with its emphasis on visuomotor processing and executive functions, tended to show lower landing loads and reduced center of pressure fluctuations, a combination that would, if it held up, indicate gentler and more stable landings. The authors are explicit that these are trends, not conclusions, and that larger trials are needed before anyone rewrites a warm-up protocol on their basis.

That caution is scientifically appropriate, but it should not obscure the study’s broader significance. The experiment demonstrates a rigorous template for asking acute-effect questions that the injury-prevention field has largely skipped, leaping from long-term program adherence straight to assumed mechanisms without checking what a single session actually does to movement quality. It also validates the unplanned jump-landing paradigm as a sensitive probe: the planned-versus-unplanned contrast produced robust, statistically significant differences across force, balance, and error outcomes, confirming that cognitive uncertainty is not a cosmetic variable but a primary driver of landing behavior. For coaches, the message is that the mental dimension of landing is measurable and meaningful, and that warm-ups which train the eyes and the decision-making circuitry alongside the muscles deserve serious investigation rather than dismissal as gimmicks.

The road ahead, as the authors note, runs through larger samples and richer biomechanics. Landing loads at the knee involve joint-specific kinematics, moments, and muscle activation patterns that a pressure plate cannot fully resolve, and future work should examine whether motor-cognitive warm-ups shift the hip and knee strategies most implicated in ligament injury. Whether the promising PEP+ trends crystallize into reliable effects will depend on trials with the statistical power this eighteen-athlete study could not muster. But the conceptual payoff is already clear: the warm-up is not merely a physical rehearsal but a cognitive one, and the seconds before a jump may shape the milliseconds of the landing that follows. In a field where a single mistimed touchdown can end a season, that insight is worth every wobble recorded on the pressure plate.

Subject of Research: Acute effects of motor-cognitive injury-prevention warm-ups on unplanned jump-landing biomechanics in team-sport athletes

Article Title: Acute effects of motor-cognitive injury-prevention warm-ups on unplanned jump-landing performance in team-sport athletes: A randomized crossover trial

Article References: Laukhardt, F., Vogt, L., Hülsdünker, T., Engeroff, T., Banzer, W., Groneberg, D., & Giesche, F. (2026). Acute effects of motor-cognitive injury-prevention warm-ups on unplanned jump-landing performance in team-sport athletes: A randomized crossover trial. PLOS One, 21(10), e0360379. https://doi.org/10.1371/journal.pone.0360379

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360379

Keywords: injury prevention, warm-up, team sports, landing biomechanics, motor-cognitive training, executive functions, reactive agility, ground reaction force, randomized crossover trial, ACL injury, neuromuscular control, PLOS One

The research builds on a long-standing theory in motor neuroscience that the central nervous system generates movement from a small set of building blocks known as motor primitives. Within this framework, discrete movements are modeled as point-attractor dynamics: the limb moves from one stable posture to another, then stops. Rhythmic movements, by contrast, are modeled as limit-cycle dynamics, producing continuous periodic oscillations with stable phase relationships. Decades of evidence, from neuroimaging to motor-learning experiments, indicate that these two movement classes recruit partly distinct neural networks. Discrete actions engage broader bilateral and non-primary motor areas, while rhythmic movements rely on more circumscribed cortical and cerebellar circuitry. Stroke patients, tellingly, often retain rhythmic arm movements better than discrete ones.

Most of that evidence, however, comes from the upper limb, where reaching is discrete by default and slow rhythmic movements have been shown to fragment into sequences of discrete submovements. Walking presents the mirror-image case: it is prototypically rhythmic, so finding discrete-like organization in gait is especially informative precisely where the framework is least expected. Slow walking is also clinically important, since reduced gait speed is common in aging and neurological disease, exactly the conditions in which rhythmic locomotor organization may be compromised. If walking speed acts as a control parameter that triggers phase-transition-like shifts in coordination, the transitions might even display hysteresis, the history dependence familiar from the classic walk-to-run transition, which occurs at a higher speed when accelerating than when decelerating.

To capture these shifts, the team recorded 18 healthy adults walking on an instrumented treadmill while a ten-camera motion capture system tracked reflective markers and wireless electrodes recorded activity from 15 lower-limb muscles on each side. Participants completed two protocols: in one, treadmill speed increased from 0.5 to 5.0 kilometers per hour in 0.5 km/h steps; in the other, it decreased along the same range. At each speed, participants completed 15 consecutive strides. The researchers then quantified movement smoothness using two complementary metrics, log dimensionless jerk (LDJ) in the time domain and spectral arc length (SPARC) in the frequency domain, applied to the antero-posterior displacement between the right and left ankles, a low-dimensional descriptor of the inter-limb oscillation that defines gait.

The smoothness results were striking. Both metrics became progressively less negative, indicating smoother movement, as speed increased. Mean LDJ values rose from roughly −16.0 at 0.5 km/h to about −10.5 at 5 km/h, while SPARC climbed from around −8.3 to −4.0. Crucially, the consistency of these changes across participants varied systematically with speed. Between 0.5 and 2.5 km/h, pairwise comparisons of smoothness showed high agreement, with 89 to 100 percent of participants showing significant differences between adjacent low-speed segments. Around 3.0 to 3.5 km/h, that agreement dropped to a moderate range, and at the highest speeds it collapsed almost entirely, with few or no participants showing significant differences between neighboring fast segments. The researchers interpret this intermediate band as a transition window in which individuals shift into a stable rhythmic attractor at slightly different speeds before converging at faster gait.

Smoothness alone, however, is an end-effector readout and cannot by itself prove that a kinematic regime shift reflects reorganized neural control rather than the mere biomechanical consequences of moving slowly. To resolve that ambiguity, the team turned to muscle synergy analysis, decomposing electromyographic signals with non-negative matrix factorization into time-invariant muscle weightings and time-varying activation profiles, selecting the minimum number of synergies that accounted for at least 90 percent of the variance. The number of modules required rose systematically with speed: at the slowest speeds, two synergies sufficed; at intermediate speeds, three; and from roughly 3 to 4 km/h onward, four synergies were needed, stabilizing at the fastest gait. In the decremental condition, the richer four-synergy organization persisted down to about 3 km/h before collapsing back to two at the slowest speeds.

That asymmetry between the incremental and decremental protocols is the study’s most intriguing detail. The neuromuscular system held on to its higher-dimensional coordination state longer when speed was falling than it took to build it when speed was rising, a pattern consistent with hysteresis in a dynamical system settling into stable attractors whose stability depends on a control parameter. The behavior echoes the well-documented hysteresis of the walk-run transition and suggests that the nervous system’s current coordination state depends on its recent history. Notably, smoothness itself showed only minimal directional differences, meaning the history dependence was evident primarily in the neuromuscular measure, while both measures converged on the same overall speed-dependent reorganization.

The link between the two levels of description was remarkably tight. Within every single participant, smoothness metrics and synergy number were strongly and positively correlated across speed segments, with a median Spearman correlation of 0.92 in both ramp directions. As gait became smoother with increasing speed, the modular organization of muscle activity grew richer, in every individual regardless of ramp direction. Merging analyses reinforced the picture: when stepping from a faster to an adjacent slower speed, the lower-speed synergies could be reconstructed with cosine similarities near 0.99 as non-negative combinations of the faster-speed modules, indicating that modules merge rather than vanish as speed drops. The authors draw a parallel to development and stroke recovery, where immature or impaired gait similarly shows fewer, merged modules, and they attribute the richer fast-walking organization to greater dynamic demands: stronger propulsion, tighter phase-specific timing, and increased balance and foot-clearance requirements.

The authors are careful about interpretation. Muscle synergies are estimated from data, and a successful reconstruction does not prove the recovered modules are neurally encoded primitives; the team treats them as a description of the structure of recorded muscle activity rather than direct evidence of discrete neural modules. Yet the speed-dependent changes were reproduced across two protocols, two decomposition levels, and an independently quantified kinematic transition, none of which would be expected from the factorization procedure alone. Limitations include treadmill rather than overground walking, some excluded EMG channels, and a predominantly female sample, though the within-subject design controls for stable participant characteristics.

The broader implications reach toward rehabilitation and wearable technology. Because movement smoothness can be estimated from inertial sensors, the discrete-rhythmic balance could eventually be monitored in real time during adaptive locomotion training, helping clinicians distinguish genuine control adaptations from the kinematic consequences of slow movement. And conceptually, the study extends the dynamic-primitives framework to its least expected domain, showing that even the body’s most iconic rhythm is, at its slowest, something else entirely: a sequence of discrete steps stitched together by a nervous system that switches control modes as the world demands.

Subject of Research: Speed-dependent transitions between discrete and rhythmic control regimes in human walking, assessed via kinematic smoothness and muscle synergies

Article Title: Speed-driven transitions between discrete and rhythmic dynamics in walking revealed by kinematic smoothness and muscle synergies

Article References: Panconi, G., Minciacchi, D., Bravi, R., & Dominici, N. (2026). Speed-driven transitions between discrete and rhythmic dynamics in walking revealed by kinematic smoothness and muscle synergies. iScience, 29(11), Article 117779. https://doi.org/10.1016/j.isci.2026.117779

Image Credits: AI Generated

DOI: 10.1016/j.isci.2026.117779

Keywords: human walking, motor control, muscle synergies, movement smoothness, motor primitives, gait analysis, hysteresis, electromyography, locomotion, dynamic primitives, treadmill, neuromuscular control

The research team, led by investigators at Deakin University in Australia, recruited fifty-six older adults spanning three distinct ageing phenotypes: eleven people with clinically diagnosed sarcopenia, twenty-two non-sarcopenic controls, and nineteen masters athletes with at least ten years of continuous competitive sport participation. Sarcopenia was diagnosed according to the Sarcopenia Definitions and Outcomes Consortium criteria, which combine low handgrip strength with slow usual gait speed. The sarcopenic participants were, on average, the oldest of the three groups at just over eighty years, while the masters athletes were the youngest at around seventy. Crucially, the researchers went to considerable lengths to ensure that age itself did not explain their findings, running sensitivity analyses with age adjustment and an exploratory age-matched comparison that preserved the central results.

The experimental task was elegantly simple in design but technically ambitious in execution. Seated with their preferred leg strapped into an ankle dynamometer, participants performed trapezoidal isometric contractions of the tibialis anterior, the shin muscle that lifts the foot and clears the toes during walking. Each contraction required ramping up to thirty percent of maximal voluntary torque, holding that plateau for twenty seconds, and ramping down again. The tibialis anterior was chosen deliberately: its control is directly relevant to foot clearance during gait, and impaired control of this muscle is linked to trips and falls. Two sixty-four-channel high-density electrode grids were placed over the muscle belly, allowing the researchers to decompose the surface EMG signal into the firing times of individual motor units, the final common pathway through which the nervous system commands muscle.

The dual-task manipulation added a cognitive burden to this motor challenge. While holding the steady contraction, participants were asked to continuously subtract seven from a starting number between seventy and ninety-nine, a classic serial subtraction task used to tax executive function. Trials were invalidated if the subtraction was interrupted for more than three seconds or if multiple errors were made, ensuring that participants genuinely engaged with both tasks. Single-task and dual-task trials were alternated in randomised order to distribute any residual fatigue evenly across conditions. Real-time visual torque feedback was displayed on a monitor with identical settings for every participant, and plateau torque remained close to the thirty percent target in all groups under both conditions, meaning that any differences in motor unit behaviour could not be attributed to differences in the force actually produced.

The headline finding was stark. Torque steadiness, quantified as the coefficient of variation of the force signal, was already poorer in the sarcopenic group during single-task contractions compared with controls and athletes. When the cognitive task was added, steadiness deteriorated further in the sarcopenic participants alone, while controls and masters athletes held their performance stable. In total, the team identified more than 8,300 motor unit spike trains across the cohort, providing an unusually rich dataset. The mean discharge rate of motor units increased similarly in all three groups during dual-tasking, rising by only about 2.6 percent, which told the researchers that the sarcopenic deterioration was not about firing harder or faster. Instead, the problem lay in the timing: the regularity of motor unit discharge, measured as the variability of inter-spike intervals, worsened markedly in the sarcopenic group under cognitive load, while it actually improved in the masters athletes and remained unchanged in controls.

To understand where in the nervous system these differences arose, the researchers turned to intramuscular coherence analysis, a technique that estimates the common synaptic input shared across the motoneuron pool. By summing the spike trains of randomly selected groups of five motor units into cumulative spike trains and computing coherence spectra across up to one hundred permutations, they quantified how strongly different motor units were driven together at different frequencies. Three frequency bands were examined separately, each thought to reflect a different source of shared neural input. Delta-band coherence, spanning one to five hertz, is associated with the low-frequency common drive linked to force fluctuations. Alpha-band coherence, from five to fifteen hertz, is associated with physiological tremor and spinal and afferent contributions. Beta-band coherence, from fifteen to thirty-five hertz, is widely linked to corticospinal coupling, the dialogue between cortex and spinal motor neurons.

The coherence results painted a nuanced picture. Delta-band coherence decreased in all three groups during dual-tasking, suggesting a broad redistribution of low-frequency common input whenever attention was divided, but because this occurred even in the steady performers, it could not explain the sarcopenia-specific loss of force control. The decisive divergence appeared in the alpha and beta bands. Only the sarcopenic group showed an increase in alpha-band coherence under cognitive load, a rise in oscillatory common input that the authors interpret as a form of neural noise, tremor-related activity that is expressed in the force signal and degrades the accuracy of force production. This increase coincided with the greater inter-spike interval variability and torque variability observed in the same participants, although the study design does not establish a causal pathway between these measures. Meanwhile, beta-band coherence rose in the sarcopenic group but fell in controls and, most prominently, in masters athletes, hinting at fundamentally different strategies for regulating cortical input when attention is stretched.

The masters athletes emerged as the most striking contrast in the study. They were the only group whose discharge regularity improved during dual-tasking, and they showed the largest reduction in beta-band coherence, consistent with a flexible, adaptable modulation of common synaptic input. The authors suggest that decades of training in dynamic environments, which demand continuous integration of sensory information, attentional shifting, decision-making and motor execution, may promote more efficient allocation of central resources and more resilient control strategies. Importantly, exploratory comparisons between endurance-type and power-type athletes showed broadly similar dual-task responses, though the small subgroup sizes make those comparisons tentative. The broader message is that neural adaptability in the ageing motor system appears modifiable, and lifelong varied training may be one route to preserving it.

The clinical implications reach well beyond the laboratory. Force steadiness has been linked to mobility performance and postural control, and dual-task ability is strongly connected to fall risk and loss of independence in older adults. In an exploratory analysis drawing on the team’s companion study, a larger dual-task increase in force variability was associated with poorer baseline functional power and mobility, but not with maximal dorsiflexion strength, suggesting that vulnerability to cognitive loading reflects broad functional capacity rather than raw muscle strength. This implies that conventional single-task strength testing may underestimate real-world risk in people with sarcopenia, precisely because everyday activities such as walking, rising from a chair and carrying objects are performed while attention is divided. The findings support interventions that go beyond resistance training alone, incorporating balance-challenging, multicomponent and dual-task exercise programmes that train the nervous system as well as the muscle, and they add momentum to a reframing of sarcopenia as a disease of the ageing motor system rather than of muscle mass alone.

Subject of Research: Neural control of force steadiness during dual-task contractions in older adults with sarcopenia

Article Title: Dual‐Tasking Exacerbates Force and Neural Control Unsteadiness in Older Adults With Sarcopenia

Article References: Orssatto, L. B. R., Clark, B. C., Scott, D., Cabral, H. V., Fernandes, G. L., & Daly, R. M. (2026). Dual‐Tasking Exacerbates Force and Neural Control Unsteadiness in Older Adults With Sarcopenia. Journal of Cachexia, Sarcopenia and Muscle, 17(5), Article e70397. https://doi.org/10.1002/jcsm.70397

Image Credits: AI Generated

DOI: 10.1002/jcsm.70397

Keywords: sarcopenia, motor units, force steadiness, dual-task, high-density EMG, coherence, ageing, masters athletes, neural drive, falls, cognitive load, neuromuscular control