Pub Date : 2025-10-22DOI: 10.1249/mss.0000000000003875
Jake H Hudgins,Mira I Schoeberlein,Brad W Wilkins
PURPOSEThe heavy-severe domain boundary can be estimated with muscle oxygen saturation (%SmO2) by determining the power at which a %SmO2 slope of zero occurs. The purpose of this study was to examine the reliability and repeatability of determining power at a %SmO2 zero-slope.METHODS30 endurance-trained participants (15 women) completed six laboratory visits. Maximal oxygen uptake and gas exchange parameters were determined via a cycling ramp test. Participants completed four weekly cycling protocols consisting of four, 4-minute stages spanning the exercise intensity domains. During each stage, %SmO2 was measured using near-infrared spectroscopy (NIRS) on the rectus femoris (Moxy Monitor, Fortiori Design). The %SmO2 zero-slope power was determined from %SmO2 responses at each stage, followed by a 4-minute confirmation stage at the predicted %SmO2 zero-slope power. Linear regression between stage power (x-axis) and the slope of the %SmO2 response during each stage (y-axis) was used to predict the power at a %SmO2 zero-slope. Differences in %SmO2 zero-slope power across visits were examined via one-way ANOVA, and reliability was assessed using the intraclass correlation coefficient (ICC 2,1) as well as the standard error of measurement (SEM), expressed as a coefficient of variation (CV).RESULTS%SmO2 zero-slope power was not significantly different across visits in both men and women combined (p=0.108), nor was it different in men and women separately. The ICC across visits was 0.953 (95%CI: 0.917-0.978; p<0.001) indicating excellent reliability with a SEM of 2.6 W or 1.2%, and a minimal difference to detect a real change (MDC) of 7.3W or 3.4% Conclusions: These results demonstrate that the power at MMSS can be reliably determined using a %SmO2 zero-slope method using NIRS.
{"title":"Reliability and Repeatability of Determining Power Associated with Maximal Metabolic Steady State Using Changes in NIRS-Derived Muscle Oxygenation.","authors":"Jake H Hudgins,Mira I Schoeberlein,Brad W Wilkins","doi":"10.1249/mss.0000000000003875","DOIUrl":"https://doi.org/10.1249/mss.0000000000003875","url":null,"abstract":"PURPOSEThe heavy-severe domain boundary can be estimated with muscle oxygen saturation (%SmO2) by determining the power at which a %SmO2 slope of zero occurs. The purpose of this study was to examine the reliability and repeatability of determining power at a %SmO2 zero-slope.METHODS30 endurance-trained participants (15 women) completed six laboratory visits. Maximal oxygen uptake and gas exchange parameters were determined via a cycling ramp test. Participants completed four weekly cycling protocols consisting of four, 4-minute stages spanning the exercise intensity domains. During each stage, %SmO2 was measured using near-infrared spectroscopy (NIRS) on the rectus femoris (Moxy Monitor, Fortiori Design). The %SmO2 zero-slope power was determined from %SmO2 responses at each stage, followed by a 4-minute confirmation stage at the predicted %SmO2 zero-slope power. Linear regression between stage power (x-axis) and the slope of the %SmO2 response during each stage (y-axis) was used to predict the power at a %SmO2 zero-slope. Differences in %SmO2 zero-slope power across visits were examined via one-way ANOVA, and reliability was assessed using the intraclass correlation coefficient (ICC 2,1) as well as the standard error of measurement (SEM), expressed as a coefficient of variation (CV).RESULTS%SmO2 zero-slope power was not significantly different across visits in both men and women combined (p=0.108), nor was it different in men and women separately. The ICC across visits was 0.953 (95%CI: 0.917-0.978; p<0.001) indicating excellent reliability with a SEM of 2.6 W or 1.2%, and a minimal difference to detect a real change (MDC) of 7.3W or 3.4% Conclusions: These results demonstrate that the power at MMSS can be reliably determined using a %SmO2 zero-slope method using NIRS.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"93 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145338647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-22DOI: 10.1249/mss.0000000000003873
Qingqing Song,Dongmei Wang,Xinmeng Zhang,Xin Luo,Yubin Ge,Peixin Shen,Qipeng Song
PURPOSEThis study evaluated the effectiveness and sustainability of a 6-week intervention combining transcranial direct current stimulation (tDCS) and transcutaneous electrical nerve stimulation (TENS) for pain and functional mobility in older adults with knee osteoarthritis (KOA). It also explored the mediation effect of pain relief on functional mobility.METHODSThirty older adults with KOA were randomly split into tDCS+TENS and TENS groups in a 1:1 ratio. The former received combined tDCS and TENS, while the latter had TENS with sham tDCS, for 6 weeks with four 20-minute sessions weekly. Twenty-seven participants finished the intervention and a 12-week follow-up (14 and 13 in each group). Assessments using the Visual Analogue Scale (VAS) for pain and the Timed Up and Go (TUG) test for mobility were conducted at week 0 (baseline), week 7 (6-week training), week 11 (4-week detraining), and week 19 (further 8-week detraining). Two-way mixed design ANOVA and a simple mediation model were used for data analysis.RESULTSSignificant time*group interactions were detected in VAS scores (p=0.009, η2p=0.391) and TUG times (p=0.011, η2p=0.397). The tDCS + TENS group showed lower VAS scores at weeks 7, 11, and 19, and lower TUG times at weeks 7 and 11 compared to week 0. The TENS group had lower scores and times at weeks 7 and 11. A significant mediation-effect of pain scores on TUG times was seen in the TENS group (95% CI: 0.008, 0.406).CONCLUSIONSThe combination of tDCS and TENS demonstrates superior and more enduring efficacy in alleviating pain and enhancing functional mobility in older adults with KOA; TENS improves functional mobility primarily through pain reduction, while the tDCS+TENS intervention likely operates via other mechanisms.
目的：本研究评估了经颅直流电刺激（tDCS）和经皮神经电刺激（TENS）联合治疗老年膝关节骨关节炎（KOA）患者疼痛和功能活动的有效性和可持续性。探讨疼痛缓解对功能活动能力的中介作用。方法将30例老年KOA患者按1:1的比例随机分为tDCS+TENS组和TENS组。前者接受tDCS和TENS联合治疗，后者接受假性tDCS联合TENS治疗，为期6周，每周4次，每次20分钟。27名参与者完成了干预和12周的随访（每组14名和13名）。在第0周（基线）、第7周（6周训练）、第11周（4周去训练）和第19周（进一步的8周去训练）使用视觉模拟量表（VAS）对疼痛进行评估，并对活动能力进行Timed Up and Go （TUG）测试。采用双向混合设计方差分析和简单中介模型进行数据分析。结果VAS评分（p=0.009, η2p=0.391）和TUG次数（p=0.011, η2p=0.397）存在显著的时间*组间交互作用。tDCS + TENS组在第7、11、19周的VAS评分较低，第7、11周的TUG次数较低。TENS组在第7周和第11周的评分和次数较低。TENS组疼痛评分对TUG次数有显著的中介效应（95% CI: 0.008, 0.406）。结论tDCS联合TENS在缓解老年KOA患者疼痛和增强功能活动能力方面具有更优、更持久的疗效；TENS主要通过减轻疼痛来改善功能活动，而tDCS+TENS干预可能通过其他机制起作用。
{"title":"Efficacy and Sustainability of tDCS Combined with TENS in Alleviating Pain and Improving Functional Mobility in Older Adults with Knee Osteoarthritis.","authors":"Qingqing Song,Dongmei Wang,Xinmeng Zhang,Xin Luo,Yubin Ge,Peixin Shen,Qipeng Song","doi":"10.1249/mss.0000000000003873","DOIUrl":"https://doi.org/10.1249/mss.0000000000003873","url":null,"abstract":"PURPOSEThis study evaluated the effectiveness and sustainability of a 6-week intervention combining transcranial direct current stimulation (tDCS) and transcutaneous electrical nerve stimulation (TENS) for pain and functional mobility in older adults with knee osteoarthritis (KOA). It also explored the mediation effect of pain relief on functional mobility.METHODSThirty older adults with KOA were randomly split into tDCS+TENS and TENS groups in a 1:1 ratio. The former received combined tDCS and TENS, while the latter had TENS with sham tDCS, for 6 weeks with four 20-minute sessions weekly. Twenty-seven participants finished the intervention and a 12-week follow-up (14 and 13 in each group). Assessments using the Visual Analogue Scale (VAS) for pain and the Timed Up and Go (TUG) test for mobility were conducted at week 0 (baseline), week 7 (6-week training), week 11 (4-week detraining), and week 19 (further 8-week detraining). Two-way mixed design ANOVA and a simple mediation model were used for data analysis.RESULTSSignificant time*group interactions were detected in VAS scores (p=0.009, η2p=0.391) and TUG times (p=0.011, η2p=0.397). The tDCS + TENS group showed lower VAS scores at weeks 7, 11, and 19, and lower TUG times at weeks 7 and 11 compared to week 0. The TENS group had lower scores and times at weeks 7 and 11. A significant mediation-effect of pain scores on TUG times was seen in the TENS group (95% CI: 0.008, 0.406).CONCLUSIONSThe combination of tDCS and TENS demonstrates superior and more enduring efficacy in alleviating pain and enhancing functional mobility in older adults with KOA; TENS improves functional mobility primarily through pain reduction, while the tDCS+TENS intervention likely operates via other mechanisms.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145338649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-16DOI: 10.1249/mss.0000000000003866
Alan J Metcalfe,Edward Mills,Trudie Chalder,Caroline J Jolley,Gerrard F Rafferty
PURPOSEMuscle endurance is commonly assessed using repeated or sustained volitional contractions, but measurement can be affected by subject cooperation and motivation. Non-volitional techniques employing direct muscle stimulation may overcome the shortcomings associated with volitional techniques. We have therefore examined the variability and reliability of both volitional and non-volitional techniques to assess quadriceps and handgrip endurance.METHODSFourteen healthy participants (10 male, age 30±7 years, height 173.3±9.2 cm, weight 67.0±12 kg) completed measurements of strength and endurance on three occasions. Hand grip (HGMVC) and quadriceps (QMVC) strength were determined from maximal voluntary contractions. Volitional hand grip endurance was determined as the time to task failure during a sustained contraction at 50% HGMVC. Volitional quadriceps endurance was assessed using repeated 5 second isometric contractions at 60% QMVC with 3 seconds rest until task failure. Non-volitional quadriceps endurance was assessed using repetitive transcutaneous electrical stimulation (30Hz, 250 milliseconds on, 750 milliseconds off for 180 seconds) at 30% QMVC. Endurance was taken as the time for force to fall to 70% of initial force. Variability was determined using the coefficient of variation and reliability using ICC.RESULTSVolitional hand grip endurance demonstrated fair variability (20.5%) and good reliability (0.81). Volitional quadriceps endurance demonstrated good variability (15.2%) and good reliability (0.76) while non-volitional quadriceps endurance demonstrated good variability (16.4%) and excellent reliability (0.92). Overall, HGMVC and QMVC demonstrated either good or very good variability and either good or excellent reliability.CONCLUSIONSBoth volitional and non-volitional measures of endurance in the hand and quadriceps muscles are reliable. Non-volitional measures of muscle endurance may be helpful in cohorts unable to perform volitional maneuvers.
{"title":"Test-Retest Variability and Reliability of Volitional and Non-Volitional Assessments of Muscle Endurance in Healthy Humans.","authors":"Alan J Metcalfe,Edward Mills,Trudie Chalder,Caroline J Jolley,Gerrard F Rafferty","doi":"10.1249/mss.0000000000003866","DOIUrl":"https://doi.org/10.1249/mss.0000000000003866","url":null,"abstract":"PURPOSEMuscle endurance is commonly assessed using repeated or sustained volitional contractions, but measurement can be affected by subject cooperation and motivation. Non-volitional techniques employing direct muscle stimulation may overcome the shortcomings associated with volitional techniques. We have therefore examined the variability and reliability of both volitional and non-volitional techniques to assess quadriceps and handgrip endurance.METHODSFourteen healthy participants (10 male, age 30±7 years, height 173.3±9.2 cm, weight 67.0±12 kg) completed measurements of strength and endurance on three occasions. Hand grip (HGMVC) and quadriceps (QMVC) strength were determined from maximal voluntary contractions. Volitional hand grip endurance was determined as the time to task failure during a sustained contraction at 50% HGMVC. Volitional quadriceps endurance was assessed using repeated 5 second isometric contractions at 60% QMVC with 3 seconds rest until task failure. Non-volitional quadriceps endurance was assessed using repetitive transcutaneous electrical stimulation (30Hz, 250 milliseconds on, 750 milliseconds off for 180 seconds) at 30% QMVC. Endurance was taken as the time for force to fall to 70% of initial force. Variability was determined using the coefficient of variation and reliability using ICC.RESULTSVolitional hand grip endurance demonstrated fair variability (20.5%) and good reliability (0.81). Volitional quadriceps endurance demonstrated good variability (15.2%) and good reliability (0.76) while non-volitional quadriceps endurance demonstrated good variability (16.4%) and excellent reliability (0.92). Overall, HGMVC and QMVC demonstrated either good or very good variability and either good or excellent reliability.CONCLUSIONSBoth volitional and non-volitional measures of endurance in the hand and quadriceps muscles are reliable. Non-volitional measures of muscle endurance may be helpful in cohorts unable to perform volitional maneuvers.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145296090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-16DOI: 10.1249/mss.0000000000003871
Jonathan Musselman,David E Price,Vicki Nelson
PURPOSEHypertension is a growing public health concern. While physicial activity is generally beneficial, the role of varying physiologic demand on elevated blood pressure risk in adolescents is not well understood. This study evaluates the relationships between blood pressure in athletes and the physiologic demands of their sports.METHODS7,127 adolescent athletes (ages 13-19) were included in a retrospective analysis of blood pressure measurement during preparticipation evaluation. Sports were classified by high or low demand for static and dynamic components. Binomial logistic regression was completed to assess associations between static and dynamic components and elevated blood pressure screening. Differences in mean blood pressures (ANOVA) and prevalence of elevated blood pressure (chi square test) were assessed between high and low demand sports participation.RESULTSParticipation in sports with a high static or low dynamic demand showed high rates of elevated blood pressure. Athletes in high static demand sports had 1.6 times greater odds of elevated blood pressure screening (p<0.0001); high dynamic demand was associated with reduced odds (0.75, p=0.006). The combination of high static and low dynamic demand resulted in the highest prevalence (17.5%). Mean systolic blood pressure was higher among high static and low dynamic participants, while diastolic pressure was not significantly different.CONCLUSIONSAthletes participating in sports with high static or low dynamic demands have a higher risk of elevated blood pressure. This suggests a need for sport-specific cardiovascular assessment and consideration of training modifications to reduce long-term cardiovascular risk. Longitudinal studies are warranted to evaluate the persistence of elevated blood pressure and clinical implications.
{"title":"Participation in High Static, Low Dynamic Demand Sports Increases Prevalence of Elevated Blood Pressure in Adolescent Athletes.","authors":"Jonathan Musselman,David E Price,Vicki Nelson","doi":"10.1249/mss.0000000000003871","DOIUrl":"https://doi.org/10.1249/mss.0000000000003871","url":null,"abstract":"PURPOSEHypertension is a growing public health concern. While physicial activity is generally beneficial, the role of varying physiologic demand on elevated blood pressure risk in adolescents is not well understood. This study evaluates the relationships between blood pressure in athletes and the physiologic demands of their sports.METHODS7,127 adolescent athletes (ages 13-19) were included in a retrospective analysis of blood pressure measurement during preparticipation evaluation. Sports were classified by high or low demand for static and dynamic components. Binomial logistic regression was completed to assess associations between static and dynamic components and elevated blood pressure screening. Differences in mean blood pressures (ANOVA) and prevalence of elevated blood pressure (chi square test) were assessed between high and low demand sports participation.RESULTSParticipation in sports with a high static or low dynamic demand showed high rates of elevated blood pressure. Athletes in high static demand sports had 1.6 times greater odds of elevated blood pressure screening (p<0.0001); high dynamic demand was associated with reduced odds (0.75, p=0.006). The combination of high static and low dynamic demand resulted in the highest prevalence (17.5%). Mean systolic blood pressure was higher among high static and low dynamic participants, while diastolic pressure was not significantly different.CONCLUSIONSAthletes participating in sports with high static or low dynamic demands have a higher risk of elevated blood pressure. This suggests a need for sport-specific cardiovascular assessment and consideration of training modifications to reduce long-term cardiovascular risk. Longitudinal studies are warranted to evaluate the persistence of elevated blood pressure and clinical implications.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145296062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-16DOI: 10.1249/mss.0000000000003869
Donghyeon Kim,Robert A Huggins,Rebecca L Stearns,Peter Figueiredo,Douglas J Casa,Yuri Hosokawa
{"title":"The Need for Greater Methodological Rigor in Evaluating Cooling Interventions.","authors":"Donghyeon Kim,Robert A Huggins,Rebecca L Stearns,Peter Figueiredo,Douglas J Casa,Yuri Hosokawa","doi":"10.1249/mss.0000000000003869","DOIUrl":"https://doi.org/10.1249/mss.0000000000003869","url":null,"abstract":"","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"354 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145296061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-16DOI: 10.1249/mss.0000000000003872
Timothy Lowe,Tharan Suresh,Evan G Oro,Michael Freedberg,Sara J Hussain,Lisa Griffin
INTRODUCTIONProlonged vibration of the hamstrings increases voluntary activation of the quadriceps in patients with anterior cruciate ligament reconstruction (ACLR). To gain insight into the mechanisms responsible for this increase, we investigated the effects of prolonged vibration of the hamstrings on spinal and cortical excitability of motor pathways to the quadriceps, and on the time course of these effects in patients post-ACLR and in non-injured age-matched participants (NI).METHODSSpinal and cortical excitability of neural pathways to the vastus medialis were assessed in 42 participants (14 ACLR, 14 NI, 14 NI Sham) before and at 0, 10, 20, 30, 45, and 60 min after prolonged (20 min) vibration of the hamstrings. The NI Sham group received no vibration. Voluntary activation of the quadriceps was evaluated with the central activation ratio technique.RESULTSIn both vibration groups (ACLR and NI), vibration induced a persistent increase in corticospinal (p < 0.001) excitability for 60 min after vibration. In the ACLR group only, vibration induced a sustained increase in spinal (H-reflex amplitude) excitability for up to 60 min following vibration (p < 0.001). In the ACLR group, an increase in voluntary activation was positively correlated with increases in spinal and corticospinal (motor evoked potential amplitude) excitability.CONCLUSIONSThe increase in voluntary activation of the quadriceps following prolonged vibration of the hamstrings is due to an increase in quadriceps spinal excitability. Furthermore, prolonged vibration of the hamstrings increases cortical and spinal excitability of neural pathways to the quadriceps for at least an hour following cessation of the vibration. Understanding these mechanisms will enable clinicians to optimize this technique and enhance rehabilitation outcomes.
{"title":"Local Vibration of the Hamstrings Induces Changes in Cortical and Spinal Excitability to the Antagonist Quadriceps Following ACL Reconstruction.","authors":"Timothy Lowe,Tharan Suresh,Evan G Oro,Michael Freedberg,Sara J Hussain,Lisa Griffin","doi":"10.1249/mss.0000000000003872","DOIUrl":"https://doi.org/10.1249/mss.0000000000003872","url":null,"abstract":"INTRODUCTIONProlonged vibration of the hamstrings increases voluntary activation of the quadriceps in patients with anterior cruciate ligament reconstruction (ACLR). To gain insight into the mechanisms responsible for this increase, we investigated the effects of prolonged vibration of the hamstrings on spinal and cortical excitability of motor pathways to the quadriceps, and on the time course of these effects in patients post-ACLR and in non-injured age-matched participants (NI).METHODSSpinal and cortical excitability of neural pathways to the vastus medialis were assessed in 42 participants (14 ACLR, 14 NI, 14 NI Sham) before and at 0, 10, 20, 30, 45, and 60 min after prolonged (20 min) vibration of the hamstrings. The NI Sham group received no vibration. Voluntary activation of the quadriceps was evaluated with the central activation ratio technique.RESULTSIn both vibration groups (ACLR and NI), vibration induced a persistent increase in corticospinal (p < 0.001) excitability for 60 min after vibration. In the ACLR group only, vibration induced a sustained increase in spinal (H-reflex amplitude) excitability for up to 60 min following vibration (p < 0.001). In the ACLR group, an increase in voluntary activation was positively correlated with increases in spinal and corticospinal (motor evoked potential amplitude) excitability.CONCLUSIONSThe increase in voluntary activation of the quadriceps following prolonged vibration of the hamstrings is due to an increase in quadriceps spinal excitability. Furthermore, prolonged vibration of the hamstrings increases cortical and spinal excitability of neural pathways to the quadriceps for at least an hour following cessation of the vibration. Understanding these mechanisms will enable clinicians to optimize this technique and enhance rehabilitation outcomes.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"92 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145296064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-16DOI: 10.1249/mss.0000000000003868
Baptiste Chanel,Nicolas Babault,Carole Cometti
INTRODUCTIONThis study aimed to compare the effects of a fatiguing eccentric exercise on the myotendinous elastic properties between men and prepubertal boys.METHODSTen prepubertal boys and ten men performed a fatiguing exercise composed of five sets of 20 maximal isokinetic eccentric contractions of the knee extensors. Before the exercise, the elastic properties of the vastus lateralis (VL), the rectus femoris (RF), and the patellar tendon (PT) were assessed using shear wave elastography to measure the shear wave velocity (SWV). These measurements were repeated immediately after the exercise (Post), 30 minutes after (Post 30 min), and 48 hours after (Post 48h).RESULTSA significant time effect was observed for SWV VL (p = 0.005), but no difference was revealed by the post-hoc tests. A significant time × age interaction (p = 0.05) was observed for SWV RF and revealed an increase at Post (p = 0.004; + 24.37% ± 36.67) and Post 30 min (p = 0.010) as compared to Pre for men, while no modification was observed for boys (Post: p = 1.000; + 0.86% ± 16.92). For PT, a significant time effect was observed (p < 0.001) and revealed an increase from Pre at Post (p < 0.001) and Post 30 min (p = 0.002), whatever the age group.CONCLUSIONSThe alterations of the myotendinous elastic properties after an eccentric exercise were age-dependent. Indeed, they were only observed in the tendon tissue in boys, while they were observed in RF and tendon tissues in men.
本研究旨在比较疲劳偏心运动对男性和青春期前男孩肌腱弹性特性的影响。方法10名青春期前男孩和10名男性进行了一项由5组20次最大等速离心膝关节伸肌收缩组成的疲劳运动。运动前，采用横波弹性成像测量横波速度（SWV），评估股外侧肌（VL）、股直肌（RF）和髌骨肌腱（PT）的弹性特性。这些测量在运动后立即（Post）、30分钟后（Post 30 min）和48小时后（Post 48h）重复进行。结果SWV VL有显著的时间效应（p = 0.005），事后检验无显著差异。与术前相比，男性SWV RF在术后（p = 0.004; + 24.37%±36.67）和术后30 min （p = 0.010）均有所增加，而男孩SWV RF无明显变化（p = 1.000; + 0.86%±16.92）。对于PT，观察到显着的时间效应（p < 0.001），并且显示从Pre at Post （p < 0.001）和Post 30 min （p = 0.002）增加，无论年龄组如何。结论偏心运动后肌腱弹性特性的改变具有年龄依赖性。事实上，它们只在男孩的肌腱组织中被观察到，而在男性的RF和肌腱组织中也被观察到。
{"title":"Comparison of the Eccentric Exercise Effects on the Myotendinous Elastic Properties Between Men and Prepubertal Boys: A Shear-Wave Elastography Study.","authors":"Baptiste Chanel,Nicolas Babault,Carole Cometti","doi":"10.1249/mss.0000000000003868","DOIUrl":"https://doi.org/10.1249/mss.0000000000003868","url":null,"abstract":"INTRODUCTIONThis study aimed to compare the effects of a fatiguing eccentric exercise on the myotendinous elastic properties between men and prepubertal boys.METHODSTen prepubertal boys and ten men performed a fatiguing exercise composed of five sets of 20 maximal isokinetic eccentric contractions of the knee extensors. Before the exercise, the elastic properties of the vastus lateralis (VL), the rectus femoris (RF), and the patellar tendon (PT) were assessed using shear wave elastography to measure the shear wave velocity (SWV). These measurements were repeated immediately after the exercise (Post), 30 minutes after (Post 30 min), and 48 hours after (Post 48h).RESULTSA significant time effect was observed for SWV VL (p = 0.005), but no difference was revealed by the post-hoc tests. A significant time × age interaction (p = 0.05) was observed for SWV RF and revealed an increase at Post (p = 0.004; + 24.37% ± 36.67) and Post 30 min (p = 0.010) as compared to Pre for men, while no modification was observed for boys (Post: p = 1.000; + 0.86% ± 16.92). For PT, a significant time effect was observed (p < 0.001) and revealed an increase from Pre at Post (p < 0.001) and Post 30 min (p = 0.002), whatever the age group.CONCLUSIONSThe alterations of the myotendinous elastic properties after an eccentric exercise were age-dependent. Indeed, they were only observed in the tendon tissue in boys, while they were observed in RF and tendon tissues in men.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145296065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PURPOSEConstant load cycling followed by a repeated-sprint ability test was compared in males and females under thermoneutral (TN), hot-dry (HD), and hot-humid (HH) conditions.METHODSTwenty-four trained participants (12 males and 12 females) were assessed under three conditions: thermoneutral (TN, 20°C, 40% RH), hot dry (HD, 40°C, 35% RH), and hot humid (HH, 31.5°C, 90% RH), with HD and HH matched to a Wet Bulb Globe Temperature of ~31°C. Each session included 40 min of constant load cycling (7.5 W/kg metabolic heat production), 5 min of passive rest, and five 6-s sprints (24-s recovery).RESULTSRectal temperature reached 38.5°C in both HD and HH, compared to 38.0°C in TN: p<0.001) after 40 min, with no sex differences (p>0.05). Heart rate was consistently higher in HD and HH than TN from 15 min onwards (p<0.001) during constant load cycling, with females exhibiting higher heart rates across all conditions (150 vs. 146 bpm; p<0.001). Mean and peak power output, alongside sprint decrement score, did not differ between conditions; however, males had greater sprint decrement scores than females (-9.5% vs. -5.2%, p<0.001).CONCLUSIONSDespite higher cardiovascular strain in females, both sexes showed comparable rectal temperature to constant load cycling, indicating similar heat tolerance in the two hot conditions. The lack of differences in repeated-sprint ability between hot environments, despite 40 min of submaximal cycling, suggests that relative humidity and ambient temperature impose comparable performance challenges during 'all out' efforts.
{"title":"Sex Differences in Exercise Responses to Constant Load Cycling and Repeated-Sprint Ability in Hot-Dry and Hot-humid Conditions.","authors":"Prashan Anbalagan,Peter Peeling,Mohammed Ihsan,Sébastien Racinais,Karen Wallman,Olivier Girard","doi":"10.1249/mss.0000000000003865","DOIUrl":"https://doi.org/10.1249/mss.0000000000003865","url":null,"abstract":"PURPOSEConstant load cycling followed by a repeated-sprint ability test was compared in males and females under thermoneutral (TN), hot-dry (HD), and hot-humid (HH) conditions.METHODSTwenty-four trained participants (12 males and 12 females) were assessed under three conditions: thermoneutral (TN, 20°C, 40% RH), hot dry (HD, 40°C, 35% RH), and hot humid (HH, 31.5°C, 90% RH), with HD and HH matched to a Wet Bulb Globe Temperature of ~31°C. Each session included 40 min of constant load cycling (7.5 W/kg metabolic heat production), 5 min of passive rest, and five 6-s sprints (24-s recovery).RESULTSRectal temperature reached 38.5°C in both HD and HH, compared to 38.0°C in TN: p<0.001) after 40 min, with no sex differences (p>0.05). Heart rate was consistently higher in HD and HH than TN from 15 min onwards (p<0.001) during constant load cycling, with females exhibiting higher heart rates across all conditions (150 vs. 146 bpm; p<0.001). Mean and peak power output, alongside sprint decrement score, did not differ between conditions; however, males had greater sprint decrement scores than females (-9.5% vs. -5.2%, p<0.001).CONCLUSIONSDespite higher cardiovascular strain in females, both sexes showed comparable rectal temperature to constant load cycling, indicating similar heat tolerance in the two hot conditions. The lack of differences in repeated-sprint ability between hot environments, despite 40 min of submaximal cycling, suggests that relative humidity and ambient temperature impose comparable performance challenges during 'all out' efforts.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145288257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PURPOSERunning economy is a key determinant of endurance performance, with recently developed advanced footwear technologies (AFT) improving running economy substantially. One key feature of AFT is the thick, compliant midsole. Previously, greater surface compliance has been associated with greater leg stiffness and enhanced running economy, suggesting that increased shoe compliance could induce similar effects and therefore at least partially explain the metabolic benefit of AFTs. However, it remains unclear whether midsole compliance replicates the effects of surface compliance on running economy and leg stiffness, and what biomechanical mechanisms underlie these improvements.METHODSNineteen well-trained male runners completed biomechanical and metabolic testing in two shoes designed to differ only in midsole compliance. Participants ran three 5-minute trials at 12 and 16 km/h on an instrumented treadmill in each shoe. During these trials, we collected 3D motion capture data, ground reaction forces, and whole-body metabolic rate via indirect calorimetry.RESULTSMore compliant footwear was associated with a 3.90% improvement in running economy (P < 0.001) and a 2.98% increase in leg stiffness (P < 0.01). Additionally, runners exhibited reduced knee flexion at midstance, leg compression, average knee extension velocity, and peak knee extensor moment with greater midsole compliance (P < 0.05). These biomechanical changes resulted in a 9.46% decrease in average positive knee joint power (P = 0.001).CONCLUSIONSGreater midsole compliance improves running economy. Altering midsole compliance primarily affects knee mechanics and average positive knee joint power. While future research should explore muscle-fascicle dynamics to directly determine the muscle-level effect, our results suggest that shoe compliance improves running economy by lowering knee extensor muscle metabolic demand.
{"title":"The Isolated Effect of Midsole Compliance on Running Economy and Biomechanics in Highly Trained Runners.","authors":"Davide Petrella,Wannes Swinnen,Nicholas Tam,Ben Lane,Benedicte Vanwanseele","doi":"10.1249/mss.0000000000003864","DOIUrl":"https://doi.org/10.1249/mss.0000000000003864","url":null,"abstract":"PURPOSERunning economy is a key determinant of endurance performance, with recently developed advanced footwear technologies (AFT) improving running economy substantially. One key feature of AFT is the thick, compliant midsole. Previously, greater surface compliance has been associated with greater leg stiffness and enhanced running economy, suggesting that increased shoe compliance could induce similar effects and therefore at least partially explain the metabolic benefit of AFTs. However, it remains unclear whether midsole compliance replicates the effects of surface compliance on running economy and leg stiffness, and what biomechanical mechanisms underlie these improvements.METHODSNineteen well-trained male runners completed biomechanical and metabolic testing in two shoes designed to differ only in midsole compliance. Participants ran three 5-minute trials at 12 and 16 km/h on an instrumented treadmill in each shoe. During these trials, we collected 3D motion capture data, ground reaction forces, and whole-body metabolic rate via indirect calorimetry.RESULTSMore compliant footwear was associated with a 3.90% improvement in running economy (P < 0.001) and a 2.98% increase in leg stiffness (P < 0.01). Additionally, runners exhibited reduced knee flexion at midstance, leg compression, average knee extension velocity, and peak knee extensor moment with greater midsole compliance (P < 0.05). These biomechanical changes resulted in a 9.46% decrease in average positive knee joint power (P = 0.001).CONCLUSIONSGreater midsole compliance improves running economy. Altering midsole compliance primarily affects knee mechanics and average positive knee joint power. While future research should explore muscle-fascicle dynamics to directly determine the muscle-level effect, our results suggest that shoe compliance improves running economy by lowering knee extensor muscle metabolic demand.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145288256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-07DOI: 10.1249/mss.0000000000003862
Zeyi Zhang,Ting Fan,Wu Jin,Youping Sun
PURPOSEAchilles tendon injuries are common during running in low-temperature environments, but the underlying biomechanical mechanisms remain unclear. This study combines machine learning with Shapley Additive exPlanations (SHAP) to identify key running biomechanics factors contributing to increased Achilles tendon stress during the running start and steady-state phases in low-temperature conditions, providing insights into injury prevention strategies for recreational runners.METHODSTrunk and lower-limb biomechanics were assessed in 126 recreational runners during running-start and steady-state phases under cold conditions. Achilles tendon stress was quantified via OpenSim modeling and ultrasound. Machine learning models-extreme gradient boosting (XGBoost), random forest (RF), and support vector regression (SVR)-combined with the SHAP framework identified key biomechanical factors influencing Achilles tendon stress.RESULTSXGBoost outperformed other models, so the SHAP framework was based on its results. During the running start phase, increased Achilles tendon stress was associated with (i) ankle dorsiflexion angles less than 12.449°, (ii) anterior ground reaction force (GRF, defined here as the forward propulsive force during running) greater than 7.143 N/kg, or (iii) contralateral pelvic lean angles exceeding 10.998°. In the steady-state phase, key factors included (i) ankle dorsiflexion angles less than 11.816°, (ii) ankle inversion moments greater than 0.187 N·m/kg, and (iii) ankle inversion angles exceeding 2.482°.CONCLUSIONSThe XGBoost-SHAP framework reveals that, under low-temperature conditions, limited ankle dorsiflexion, excessive anterior GRF, and increased pelvic lean contribute to elevated Achilles tendon stress during the running start phase. In the steady-state phase, reduced ankle dorsiflexion, excessive ankle inversion moments, and greater ankle inversion angles are potentially associated with higher tendon loading. Targeted gait training may reduce these risk factors and prevent Achilles tendon injuries in low-temperature environments.
{"title":"Using Machine Learning and SHAP to Identify Biomechanical Risk Factors for Increased Achilles Tendon Stress during Low-Temperature Running.","authors":"Zeyi Zhang,Ting Fan,Wu Jin,Youping Sun","doi":"10.1249/mss.0000000000003862","DOIUrl":"https://doi.org/10.1249/mss.0000000000003862","url":null,"abstract":"PURPOSEAchilles tendon injuries are common during running in low-temperature environments, but the underlying biomechanical mechanisms remain unclear. This study combines machine learning with Shapley Additive exPlanations (SHAP) to identify key running biomechanics factors contributing to increased Achilles tendon stress during the running start and steady-state phases in low-temperature conditions, providing insights into injury prevention strategies for recreational runners.METHODSTrunk and lower-limb biomechanics were assessed in 126 recreational runners during running-start and steady-state phases under cold conditions. Achilles tendon stress was quantified via OpenSim modeling and ultrasound. Machine learning models-extreme gradient boosting (XGBoost), random forest (RF), and support vector regression (SVR)-combined with the SHAP framework identified key biomechanical factors influencing Achilles tendon stress.RESULTSXGBoost outperformed other models, so the SHAP framework was based on its results. During the running start phase, increased Achilles tendon stress was associated with (i) ankle dorsiflexion angles less than 12.449°, (ii) anterior ground reaction force (GRF, defined here as the forward propulsive force during running) greater than 7.143 N/kg, or (iii) contralateral pelvic lean angles exceeding 10.998°. In the steady-state phase, key factors included (i) ankle dorsiflexion angles less than 11.816°, (ii) ankle inversion moments greater than 0.187 N·m/kg, and (iii) ankle inversion angles exceeding 2.482°.CONCLUSIONSThe XGBoost-SHAP framework reveals that, under low-temperature conditions, limited ankle dorsiflexion, excessive anterior GRF, and increased pelvic lean contribute to elevated Achilles tendon stress during the running start phase. In the steady-state phase, reduced ankle dorsiflexion, excessive ankle inversion moments, and greater ankle inversion angles are potentially associated with higher tendon loading. Targeted gait training may reduce these risk factors and prevent Achilles tendon injuries in low-temperature environments.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"81 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145235573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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