Academic Information | How is the recovery level of muscle fatigue "seen"?

Xijian Technology launches research on portable mechanical imaging devices, published in an authoritative international sports medicine journalSports Medicine Open.

Recently, Professor Cao Yanping's research group from the Department of Engineering Mechanics at Tsinghua University, together with Associate Professor Cui Yixiong's team from Beijing Sport University, published an article in an authoritative international sports medicine journalSports Medicine OpenPublished an article titled“Assessing the Recovery of Muscle Fatigue Using Shear Wave Elastography”Original research paper on evaluating muscle fatigue recovery based on shear wave elastography（DOI: 10.1186/s40798-026-00991-5）.

This study adoptsThe portable ultrasound mechanical imaging equipment launched by Xijian TechnologyFor the first time, a systematic evaluation was conducted on the effects of different genders, training backgrounds, and limb strengths on the changes in shear modulus during muscle fatigue recovery, providing a new quantitative tool and evidence-based basis for personalized fatigue monitoring in sports science and rehabilitation medicine.

The article was published in:Sports Medicine Openperiodical,Sports Medicine Openis caused bySpringer NatureThe top open access (OA) journal in the field of international sports medicine.

The journal has an impact factor of 5.9 in 2025 and has long been ranked in the field of sports scienceQ1、 Top 3% (in the field of sports science)Its published research has been widely cited by scholars and practitioners in the fields of sports science, rehabilitation medicine, and sports training worldwide. The publication of this study in this journal marks the recognition of portable quantitative muscle mechanics technology by the top academic community in international sports medicine.

Why does muscle fatigue recovery need to be 'seen'?

In sports training, rehabilitation therapy, and even daily high workload work, there are often questions such as "whether you are tired" and "to what extent have you recovered". These seemingly simple questions directly determine whether to continue training, reduce workload, and enter the stage of intensive rehabilitation in the next step.For a long time, such judgments have often relied on subjective soreness, decreased strength performance, and empirical observation——But subjective similarity does not necessarily mean that the internal state of the muscles is the same.

From a biomechanical perspective, the recovery of muscle fatigue is often accompanied by changes in passive stiffness, micro injuries, delayed onset muscle soreness (DOMS), and local inflammatory responses. Used in researchShear modulus GIt can be understood as a quantitative indicator of the degree of stiffness and tension of muscles in a passive state.Through continuous monitoring of this indicatorIt is expected to transform the recovery process that relied on experience judgment in the past intoComparable, traceable, and interpretable objective dataThis is a crucial step from "judging by feeling" to "expressing with mechanical data".

How was this study completed?

Subjects and Experimental Design

A total of 51 participants aged 18-25 were included in the study, including 35 athletes (all at the provincial level or above, with a weekly training volume of approximately 10-12 hours) and 16 non athletes, with balanced coverage between men and women. The research teamUnilateral dumbbell eccentric elbow flexion trainingAs a fatigue induction method, the load is set at 90% 1RM: the first three groups complete 10 repetitions each, and the last group exhausts to induce biceps fatigue as stably as possible.

Measurement plan

The research team, in a unified position, conductedBaseline, immediately after exercise, 24 hours and 48 hoursMeasure the biceps on the dominant and non dominant sides at four time points.

The measuring equipment isThe portable ultrasound mechanical imaging equipment launched by Xijian Technology.This device adopts mechanical vibration excitation technology,For superficial muscle groups such as the biceps, excellent signal penetration and high signal-to-noise ratio can be ensured.With its extremely portable body and minimalist operation, it effectively breaks through the scene limitations of traditional devices,Perfectly adapted for real-time dynamic assessment at the sports field and rehabilitation front line.

Four key points to understand the core findings of this study

Discovery 1: Time variation is the most clear influencing factor

In the overall linear mixed effects model,The time factor has the most significant impact on G (F=14.86, P<0.001)However, there were no significant main effects observed in gender/training status group differences and limb dominance.This indicates that passive muscle stiffness presents a significant impact on exercise fatigue and recovery processesHighly quantifiable and regularThe dynamic evolution.

Core significance:Portable ultrasound mechanical imaging devices can "see" the dynamic process of muscle fatigue to recovery, rather than just providing a snapshot of a static moment.

Discovery 2: Training background shapes different recovery curves

• Male athletes:Immediately after exercise, the G value increased and returned to baseline within 48 hours, showing a rapid recovery pattern;

• Non athlete males:The G value significantly increased both immediately and 24 hours, and returned to baseline at 48 hours with a slightly slower recovery;

• Non athlete women:The G value continues to increase immediately and 24 hours, and there is a bilateral difference at 24 hours - the recovery is slower and asymmetric;

• Female athletes:There was no significant fluctuation in G values at all four time points - the training adaptation effect was more prominent in women.

   

Core significance:Under the same fatigue load, the individual's recovery process is significantly influenced by gender and training background, highlighting the blind spots of traditional standardized intervention programs. Future exercise intervention and rehabilitation guidance should shift towards personalized recovery paths.

Discovery 3: Asymmetric recovery between limbs deserves attention

Although the main effect of limb dominance in the overall model is not significant, there are significant differences in specific populations——Non athlete women showed significant bilateral G differences within 24 hours (P=0.01, ES=1.14)The recovery rhythm of the dominant and non dominant sides is not synchronized.

Core significance:Functional recovery is not a single standardized trajectory. The heterogeneity between individuals and the asymmetry of limbs on both sides need to be integrated into the dynamic monitoring system, which further highlights the core value of personalized local mechanical monitoring.

Discovery 4: Portable ultrasound mechanical imaging shows practical potential in on-site monitoring

This study validated the effectiveness of portable devices inReal sports scenesFeasibility: 51 subjects, 4 time points, bilateral measurements, all completed by operators with more than 2 years of experience in standardized positions. The data display device has good measurement stability and clinical interpretability.

Core significance:Compared to traditional ultrasound elastography systems that are limited by device size and high cost, this portable device breaks through the barriers of laboratory environments and successfully extends the objective quantitative evaluation of muscle mechanics to real scenarios such as training sites, post competition interventions, and grassroots clinical settings.

Why is this job worth paying attention to?

Whether you are a researcher, coach, or clinical doctor, the value of this research points in the same direction:Moving the assessment of muscle fatigue and recovery from empirical judgment to objective quantification.

Specifically, it provides a reusable research paradigm (portable ultrasound mechanical imaging+centrifugal fatigue model+linear mixed effects statistics), revealing the interactive effects of gender and training background on recovery; It verifies the feasibility of portable devices in continuous on-site monitoring - immediate evaluation after the game, confirmation of recovery status before the next day's training, tracking load accumulation during periodic training, all of which have a foundation for implementation; It also provides a more objective supplementary dimension than palpation and subjective scoring for clinical decision-making such as rehabilitation progress assessment, timing of return to exercise, and postoperative bilateral comparison.

The significance of this paper lies in promoting muscle fatigue and recovery fromJudging by intuition,Gradually moving towardsExpressed using mechanical data.For sports medicine, rehabilitation medicine, and training science, this change means identifying fatigue accumulation and injury risks earlier, arranging training loads and recovery cycles more accurately, and also means that more individualized decisions have the opportunity to be based on objective evidence.

In the future, Xijian Technology will continue to deepen its layout around the quantitative and biomechanical imaging platforms of soft tissue mechanics, and promote the practical application of related technologies in sports health, clinical diagnosis and treatment, and scientific research transformation - to truly improve muscle state'Visible'Let the rhythm truly recover'Quantified'Make the decision-making process more efficientThere is evidence to rely on.