PURPOSENeuromuscular electrical stimulation (NMES) combined with blood flow restriction (BFR) is a promising strategy to prevent muscle atrophy when resistance training is not feasible, though its efficacy may be limited by fatigue. This study examined whether low-level laser therapy (LLLT) can serve as an ergogenic aid during combined NMES-BFR training.METHODSThirty adults were assigned to BFR or BFR+LLLT groups (n=15). Both groups underwent a 3-week wrist extension training on the non-dominant limb using combined NMES and BFR. The BFR+LLLT group received 60 J of 850 nm laser therapy to the extensor carpi radialis longus (ECRL) before each session; the BFR group received sham treatment. Outcomes included MVC and 40% MVC submaximal force-tracking, with EMG recorded from the ECRL and ECRB muscles.RESULTSThe BFR+LLLT group exhibited a greater post-test/pre-test MVC ratio (1.154 ± 0.127) than the control group (1.040 ± 0.058) (P = .004). Although the post-/pre-test ratio of force-tracking error did not differ between groups (P > 0.05), training-related changes in motor unit discharge strategies in the ECRL and ECRB were more pronounced in the BFR+LLLT group. Following training, the BFR+LLLT group exhibited a steeper regression slope between the inter-spike interval and recruitment threshold in both muscles (P < 0.001), a pattern that was less evident in the BFR group. In addition, the post-/pre-test ratio of the common drive index (CDI) within and between the ECRL and ECRB muscles decreased in the BFR+LLLT group, in contrast to a significant training-related increase observed in the BFR group (P < 0.001).CONCLUSIONSPre-exposure to LLLT enhances force output after BFR-NMES training and improves neuromuscular efficiency by increasing motor synergy flexibility, thereby preserving force scaling during submaximal contractions.
{"title":"Training Benefits and Motor Unit Remodeling after Ischemic Neuromuscular Electrical Stimulation with Low-Level Laser Pre-Exposure.","authors":"Yi-Ching Chen,Chia-Chan Wu,Yen-Ting Lin,Pei-Fen Lee,Ing-Shiou Hwang","doi":"10.1249/mss.0000000000003860","DOIUrl":"https://doi.org/10.1249/mss.0000000000003860","url":null,"abstract":"PURPOSENeuromuscular electrical stimulation (NMES) combined with blood flow restriction (BFR) is a promising strategy to prevent muscle atrophy when resistance training is not feasible, though its efficacy may be limited by fatigue. This study examined whether low-level laser therapy (LLLT) can serve as an ergogenic aid during combined NMES-BFR training.METHODSThirty adults were assigned to BFR or BFR+LLLT groups (n=15). Both groups underwent a 3-week wrist extension training on the non-dominant limb using combined NMES and BFR. The BFR+LLLT group received 60 J of 850 nm laser therapy to the extensor carpi radialis longus (ECRL) before each session; the BFR group received sham treatment. Outcomes included MVC and 40% MVC submaximal force-tracking, with EMG recorded from the ECRL and ECRB muscles.RESULTSThe BFR+LLLT group exhibited a greater post-test/pre-test MVC ratio (1.154 ± 0.127) than the control group (1.040 ± 0.058) (P = .004). Although the post-/pre-test ratio of force-tracking error did not differ between groups (P > 0.05), training-related changes in motor unit discharge strategies in the ECRL and ECRB were more pronounced in the BFR+LLLT group. Following training, the BFR+LLLT group exhibited a steeper regression slope between the inter-spike interval and recruitment threshold in both muscles (P < 0.001), a pattern that was less evident in the BFR group. In addition, the post-/pre-test ratio of the common drive index (CDI) within and between the ECRL and ECRB muscles decreased in the BFR+LLLT group, in contrast to a significant training-related increase observed in the BFR group (P < 0.001).CONCLUSIONSPre-exposure to LLLT enhances force output after BFR-NMES training and improves neuromuscular efficiency by increasing motor synergy flexibility, thereby preserving force scaling during submaximal contractions.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145235575","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.0000000000003859
Mohamed Gomaa Sobeeh,Raza N Malik,Thomas Thordarson,Katharine D Currie,Michèle Hubli,Christopher R West,Rahul Sachdeva,Andrei Krassioukov
BACKGROUNDOrthostatic hypotension (OH) is classified into three subtypes based on when blood pressure (BP) drops during an orthostatic challenge: initial (IOH; within <15 seconds), classic (COH; within 3 minutes), and delayed (DOH; after 3 minutes). These subtypes have varying degrees of sympathetic dysfunction. OH subtypes have not been characterized after spinal cord injury (SCI), potentially leaving many undiagnosed. This study determined the prevalence and severity of autonomic impairment across OH subtypes in SCI athletes.METHODNinety-nine Paralympic athletes with chronic SCI underwent BP and heart rate (HR) assessments while supine and during a sit-up test to classify OH subtypes. Autonomic functions were assessed using the Valsalva maneuver (VM) and by calculating Valsalva ratio (VR), total recovery, pressure recovery time (PRT), and overshoot. Lastly, we examined the distribution of OH across the International Wheelchair Rugby Federation (IWRF) Classification in SCI-rugby athletes.RESULTS33.3% of the athletes experienced OH, which included 10.1% with IOH, 9.1% with COH, and 14.1% with DOH. Compared to athletes without OH, those with OH exhibited prolonged PRT (p = 0.02) and blunted overshoot (p = 0.006) during VM. The altered VM metrics were associated with hemodynamic changes during the sit-up test. OH presence was distributed throughout all IWRF classifications.CONCLUSIONSSCI athletes can experience different subtypes of OH that might interfere with sports performance and cognition. Recognizing athletes with DOH is important since this group may be missed if their orthostatic challenge test is terminated early. Evaluation of VM outcomes could supplement an orthostatic challenge to provide valuable insight into autonomic dysfunctions after SCI. Future research is required to check how the presence of OH throughout IWRF classifications can affect performance.
{"title":"Uncovering the Spectrum of Orthostatic Hypotension in Athletes with Spinal Cord Injury: Implications for Diagnosis, Classification, and Performance.","authors":"Mohamed Gomaa Sobeeh,Raza N Malik,Thomas Thordarson,Katharine D Currie,Michèle Hubli,Christopher R West,Rahul Sachdeva,Andrei Krassioukov","doi":"10.1249/mss.0000000000003859","DOIUrl":"https://doi.org/10.1249/mss.0000000000003859","url":null,"abstract":"BACKGROUNDOrthostatic hypotension (OH) is classified into three subtypes based on when blood pressure (BP) drops during an orthostatic challenge: initial (IOH; within <15 seconds), classic (COH; within 3 minutes), and delayed (DOH; after 3 minutes). These subtypes have varying degrees of sympathetic dysfunction. OH subtypes have not been characterized after spinal cord injury (SCI), potentially leaving many undiagnosed. This study determined the prevalence and severity of autonomic impairment across OH subtypes in SCI athletes.METHODNinety-nine Paralympic athletes with chronic SCI underwent BP and heart rate (HR) assessments while supine and during a sit-up test to classify OH subtypes. Autonomic functions were assessed using the Valsalva maneuver (VM) and by calculating Valsalva ratio (VR), total recovery, pressure recovery time (PRT), and overshoot. Lastly, we examined the distribution of OH across the International Wheelchair Rugby Federation (IWRF) Classification in SCI-rugby athletes.RESULTS33.3% of the athletes experienced OH, which included 10.1% with IOH, 9.1% with COH, and 14.1% with DOH. Compared to athletes without OH, those with OH exhibited prolonged PRT (p = 0.02) and blunted overshoot (p = 0.006) during VM. The altered VM metrics were associated with hemodynamic changes during the sit-up test. OH presence was distributed throughout all IWRF classifications.CONCLUSIONSSCI athletes can experience different subtypes of OH that might interfere with sports performance and cognition. Recognizing athletes with DOH is important since this group may be missed if their orthostatic challenge test is terminated early. Evaluation of VM outcomes could supplement an orthostatic challenge to provide valuable insight into autonomic dysfunctions after SCI. Future research is required to check how the presence of OH throughout IWRF classifications can affect performance.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"109 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145235593","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}
PURPOSEDespite evidence of phase-dependent performance variations during the menstrual cycle (MC) and potential impairments under oral contraceptives (OC) use, findings remain inconsistent. We studied psycho-physiological and performance fluctuations using a feasible, standardized monitoring battery.METHODSTwenty-two naturally-menstruating women and six OC-using women performed standardized tests in specified phases (MC: early follicular (EFP), ovulatory (OP), midluteal (MLP); OC: early inactive pill (EIPP), late inactive pill (LIPP), mid-active pill phase (MAPP)). Testing included the Short Recovery and Stress Scale (SRSS), heart rate time series assessment at rest and during 15-minute submaximal cycling with three intensity stages, including blood lactate testing and ratings of perceived exertion (RPE). Motor performance was assessed via handgrip strength and countermovement rebound jumps.RESULTSSRSS subscales emotional balance (EB; p=0.038) and emotional imbalance (EI; p=0.031) were significantly affected by MC phase, with lower EB (3.23 vs. 4.08, p=0.034, d=-0.55) and higher EI (2.66 vs. 1.77, p=0.039, d=0.57) in EFP compared to OP. In OC, all subscales except EI showed substantial deterioration in EIPP compared to LIPP or MAPP (d>0.80; inferential statistics not reported due to low sample size). RPE during submaximal cycling showed significant MC effects (p < 0.001), with higher RPE in EFP vs. OP for the first stage (11.9 vs. 11.3, p=0.024, d=0.59). Substantial higher RPE during first stage was also observed for OC in EIPP compared to LIPP (d=1.55). No further significant phase effects were found.CONCLUSIONSEFP and EIPP were linked to higher RPE during submaximal cycling, increased stress, and lower recovery in SRSS. These findings emphasize the role of hormonal fluctuations in psychological outcomes, highlighting the need for individualized monitoring to optimize training and recovery.
目的：尽管有证据表明在月经周期（MC）和口服避孕药（OC）使用的潜在损害阶段依赖的性能变化，研究结果仍然不一致。我们使用一种可行的、标准化的监测电池来研究心理生理和性能波动。方法22名自然月经妇女和6名使用oc的妇女在指定的阶段（MC：卵泡早期（EFP）、排卵期（OP）、黄体中期（MLP））进行标准化检测；OC：早期无效期（EIPP）、晚期无效期（LIPP）、中期无效期（MAPP）。测试包括短期恢复和压力量表（SRSS），休息时心率时间序列评估和15分钟次最大循环三个强度阶段，包括血乳酸测试和感知运动评分（RPE）。运动表现通过握力和反向运动反弹跳跃来评估。结果ssrss子量表情绪平衡（EB, p=0.038）和情绪失衡（EI, p=0.031）均受MC期的显著影响，EFP的EB较op低（3.23 vs. 4.08, p=0.034, d=-0.55）， EI较高（2.66 vs. 1.77, p=0.039, d=0.57）。在OC中，除EI外，所有子量表的EIPP较LIPP或MAPP显著恶化（d>0.80，由于样本量小，未报道推论统计）。亚最大循环期间的RPE表现出显著的MC效应（p < 0.001）， EFP阶段的RPE高于OP阶段（11.9 vs. 11.3, p=0.024, d=0.59）。与LIPP相比，EIPP的OC在第一阶段的RPE也明显更高（d=1.55）。没有发现进一步显著的相位效应。结论sefp和EIPP与次最大循环时较高的RPE、应激增加和较低的恢复有关。这些发现强调了激素波动在心理结果中的作用，强调了个性化监测以优化训练和恢复的必要性。
{"title":"Psychological But Not Motor Performance and Physiological Metrics Are Influenced in Menstrual Cycle Monitoring During Rest and Submaximal Cycling.","authors":"Marcelle Schaffarczyk,Tobias Hipp,Katharina Fuchs,Lennart Reichelt,Lucie Rückemann,Thomas Gronwald","doi":"10.1249/mss.0000000000003861","DOIUrl":"https://doi.org/10.1249/mss.0000000000003861","url":null,"abstract":"PURPOSEDespite evidence of phase-dependent performance variations during the menstrual cycle (MC) and potential impairments under oral contraceptives (OC) use, findings remain inconsistent. We studied psycho-physiological and performance fluctuations using a feasible, standardized monitoring battery.METHODSTwenty-two naturally-menstruating women and six OC-using women performed standardized tests in specified phases (MC: early follicular (EFP), ovulatory (OP), midluteal (MLP); OC: early inactive pill (EIPP), late inactive pill (LIPP), mid-active pill phase (MAPP)). Testing included the Short Recovery and Stress Scale (SRSS), heart rate time series assessment at rest and during 15-minute submaximal cycling with three intensity stages, including blood lactate testing and ratings of perceived exertion (RPE). Motor performance was assessed via handgrip strength and countermovement rebound jumps.RESULTSSRSS subscales emotional balance (EB; p=0.038) and emotional imbalance (EI; p=0.031) were significantly affected by MC phase, with lower EB (3.23 vs. 4.08, p=0.034, d=-0.55) and higher EI (2.66 vs. 1.77, p=0.039, d=0.57) in EFP compared to OP. In OC, all subscales except EI showed substantial deterioration in EIPP compared to LIPP or MAPP (d>0.80; inferential statistics not reported due to low sample size). RPE during submaximal cycling showed significant MC effects (p < 0.001), with higher RPE in EFP vs. OP for the first stage (11.9 vs. 11.3, p=0.024, d=0.59). Substantial higher RPE during first stage was also observed for OC in EIPP compared to LIPP (d=1.55). No further significant phase effects were found.CONCLUSIONSEFP and EIPP were linked to higher RPE during submaximal cycling, increased stress, and lower recovery in SRSS. These findings emphasize the role of hormonal fluctuations in psychological outcomes, highlighting the need for individualized monitoring to optimize training and recovery.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145235576","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}
PURPOSETo investigate the potential efficacy of spinal cord transcutaneous stimulation (scTS) priming to enhance lower limb neuromuscular performance during a subsequent power training session.METHODSEleven young active males (age: 21.3±1.6 years) participated in this randomized crossover, sham-controlled study. The priming protocol consisted of the application of scTS or sham stimulation (Sham) at rest and during warm-up for approximately 25 minutes. Force, velocity and power as well as electromyography (EMG) of lower limbs generated during unilateral half-squats on a Smith machine were assessed over two separate experimental sessions (scTS or Sham) for: (i) four power training sets, each including six unilateral repetitions with (ii) the last (fourth) set continuing to failure.RESULTSPeak and mean power generated during the four power training sets preceded by scTS priming were significantly higher (11%, p<0.001 and 14%, p=0.008, respectively) than those generated in the Sham session. Similar trends were also shown by velocity, force and total impulse of force. Exploratory EMG analysis revealed that scTS priming favoured an overall improved activation of the vastus lateralis during the concentric phase. Higher peak and mean power outputs (13%, p=0.006, and 24%, p=0.014, respectively), associated with higher EMG amplitude of vastus lateralis, were promoted by scTS priming also for the last set to failure, which resulted in a similar number of repetitions between the scTS (32±17) and Sham priming (32±19) sessions.CONCLUSIONSscTS priming enhanced neuromuscular outcomes during a simulated lower limb power training session. Further studies should implement scTS priming throughout a longitudinal power training intervention and assess its potential to enhance training-induced neuromuscular adaptations.
{"title":"Spinal Cord Transcutaneous Stimulation Priming Largely Enhances Lower Limb Performance during a Simulated Power Training Session in Young Active Males.","authors":"Simone Zaccaron,Lara Mari,Mattia D'Alleva,Jacopo Stafuzza,Stefano Lazzer,Enrico Rejc","doi":"10.1249/mss.0000000000003855","DOIUrl":"https://doi.org/10.1249/mss.0000000000003855","url":null,"abstract":"PURPOSETo investigate the potential efficacy of spinal cord transcutaneous stimulation (scTS) priming to enhance lower limb neuromuscular performance during a subsequent power training session.METHODSEleven young active males (age: 21.3±1.6 years) participated in this randomized crossover, sham-controlled study. The priming protocol consisted of the application of scTS or sham stimulation (Sham) at rest and during warm-up for approximately 25 minutes. Force, velocity and power as well as electromyography (EMG) of lower limbs generated during unilateral half-squats on a Smith machine were assessed over two separate experimental sessions (scTS or Sham) for: (i) four power training sets, each including six unilateral repetitions with (ii) the last (fourth) set continuing to failure.RESULTSPeak and mean power generated during the four power training sets preceded by scTS priming were significantly higher (11%, p<0.001 and 14%, p=0.008, respectively) than those generated in the Sham session. Similar trends were also shown by velocity, force and total impulse of force. Exploratory EMG analysis revealed that scTS priming favoured an overall improved activation of the vastus lateralis during the concentric phase. Higher peak and mean power outputs (13%, p=0.006, and 24%, p=0.014, respectively), associated with higher EMG amplitude of vastus lateralis, were promoted by scTS priming also for the last set to failure, which resulted in a similar number of repetitions between the scTS (32±17) and Sham priming (32±19) sessions.CONCLUSIONSscTS priming enhanced neuromuscular outcomes during a simulated lower limb power training session. Further studies should implement scTS priming throughout a longitudinal power training intervention and assess its potential to enhance training-induced neuromuscular adaptations.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145194696","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}
PURPOSEInvestigate the effects of two consecutive demanding military field exercises on iron status and associations with physical performance in male and female conscripts, and assess potential sex differences.METHODSBlood sampling and physical tests were performed before a 6-day field exercise (Exercise I), during a 2-week recovery period and after a second 10-day field exercise (Exercise II) in 23 men and 12 women (median age 19). Of these, 21 men and 9 women completed Exercise II.RESULTSA large proportion of men and women had low iron status prior to the field exercises, including suboptimal ferritin levels in 67% of women and low hemoglobin concentrations in 57% of men. Several iron biomarkers, except ferritin, decreased in response to Exercise I followed by an increase during the recovery period and a decrease in response to Exercise II. Ferritin levels, inflammation- and tissue damage biomarkers increased in response to Exercise I, decreased during recovery and remained unchanged in response to Exercise II. Red blood cells and hemoglobin levels were unaffected by Exercise I, but increased during recovery, and decreased in men only in response to Exercise II. Iron saturation decreased more in women (-10.4 [-14.3, -6.5]%) than men (-5.5 [-8.3, -2.6]%) and ferritin increased more in men (79.5 [69.0, 90.0] µg/L) than women (42.8 [28.3, 57.2] µg/L) in response to Exercise I. Recovery of jump performance correlated with increased iron and iron saturation in men and increased red blood cells and hemoglobin in women.CONCLUSIONSIron status was diminished after the field exercises in both sexes and the decrease was slightly more pronounced in women. The recovery period was not sufficient to ensure full restoration of iron status which may have impacted physical performance. The results encourage future investigations into individualized improvement in iron status prior to, and possibly during, strenuous military training.
{"title":"Effects of Two Consecutive Demanding Military Field Exercises on Iron Status in Male and Female Conscripts.","authors":"Stine Sofie Strømland,Hilde Kristin Teien,Nikolai B Aunbakk,Olav Vikmoen,Rita Tansø,Truls Raastad,Kathrine Frey Frøslie,Siv Kjølsrud Bøhn","doi":"10.1249/mss.0000000000003857","DOIUrl":"https://doi.org/10.1249/mss.0000000000003857","url":null,"abstract":"PURPOSEInvestigate the effects of two consecutive demanding military field exercises on iron status and associations with physical performance in male and female conscripts, and assess potential sex differences.METHODSBlood sampling and physical tests were performed before a 6-day field exercise (Exercise I), during a 2-week recovery period and after a second 10-day field exercise (Exercise II) in 23 men and 12 women (median age 19). Of these, 21 men and 9 women completed Exercise II.RESULTSA large proportion of men and women had low iron status prior to the field exercises, including suboptimal ferritin levels in 67% of women and low hemoglobin concentrations in 57% of men. Several iron biomarkers, except ferritin, decreased in response to Exercise I followed by an increase during the recovery period and a decrease in response to Exercise II. Ferritin levels, inflammation- and tissue damage biomarkers increased in response to Exercise I, decreased during recovery and remained unchanged in response to Exercise II. Red blood cells and hemoglobin levels were unaffected by Exercise I, but increased during recovery, and decreased in men only in response to Exercise II. Iron saturation decreased more in women (-10.4 [-14.3, -6.5]%) than men (-5.5 [-8.3, -2.6]%) and ferritin increased more in men (79.5 [69.0, 90.0] µg/L) than women (42.8 [28.3, 57.2] µg/L) in response to Exercise I. Recovery of jump performance correlated with increased iron and iron saturation in men and increased red blood cells and hemoglobin in women.CONCLUSIONSIron status was diminished after the field exercises in both sexes and the decrease was slightly more pronounced in women. The recovery period was not sufficient to ensure full restoration of iron status which may have impacted physical performance. The results encourage future investigations into individualized improvement in iron status prior to, and possibly during, strenuous military training.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145194761","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 : 2025-09-30DOI: 10.1249/mss.0000000000003854
Morgan N Broniec,Kimberly Norland,Jacob Looney,Reva Crandall,Jeffrey Thomas,Xiaoling Wang,Ryan A Harris
INTRODUCTIONThe role of skeletal muscle health on preventing and ameliorating chronic disease is emerging. The improvements in skeletal muscle metabolism are likely mediated by myokines, such as myostatin, IL-6, and decorin. Whether or not basal skeletal muscle health contributes to the myokine response to Whole body vibration (WBV), an exercise mimetic, has yet to be elucidated.METHODSData from Sixty-three young adults (32.5± 0.7 years, 57.1% female, 42.9% non-Hispanic Black) were included from a longitudinal twin cohort study. Skeletal muscle oxidative capacity (SMOC) was determined using near-infrared spectroscopy by measuring the rate of skeletal muscle oxygen consumption after stimulation and was represented as a rate constant averaged over three trials (AvgRC). The acute WBV protocol consisted of 10 cycles of 1 min of vibration exercise followed by 30s of standing rest. Blood was collected at baseline (PRE), immediately post, and 1h, 3h, and 24h post WBV and myokine concentrations of IL-6, myostatin, and decorin were measured at each of these timepoints. Participants were divided into two groups by SMOC: low skeletal muscle oxidative capacity (AvgRC < 1.82) and high skeletal muscle oxidative capacity (AvgRC > 2.13).RESULTSParticipant characteristics including age, BMI, body fat percentage, handgrip, and skeletal muscle index (SMI) were similar between groups. SMOC was positively associated with myostatin at baseline (ß= 564.6, SE=232.4, p=0.045) and 24H following WBV (ß= 661.0, SE=189.4, p=0.029). In addition, a significantly higher overall myostatin (p=0.026) and IL-6 response (p=0.001) to WBV was observed in in the high skeletal muscle oxidative capacity group when compared to the low skeletal muscle oxidative capacity group.CONCLUSIONSHigher skeletal muscle oxidative capacity is associated with a greater myostatin and IL-6 response to acute WBV. These data suggest that a higher SMOC at baseline may positively impact the myokine response to WBV, independent of adiposity, and demonstrates the importance of skeletal muscle health on preventing and ameliorating chronic disease.
{"title":"Increased Skeletal Muscle Oxidative Capacity Augments the Myokine Response to Whole Body Vibration.","authors":"Morgan N Broniec,Kimberly Norland,Jacob Looney,Reva Crandall,Jeffrey Thomas,Xiaoling Wang,Ryan A Harris","doi":"10.1249/mss.0000000000003854","DOIUrl":"https://doi.org/10.1249/mss.0000000000003854","url":null,"abstract":"INTRODUCTIONThe role of skeletal muscle health on preventing and ameliorating chronic disease is emerging. The improvements in skeletal muscle metabolism are likely mediated by myokines, such as myostatin, IL-6, and decorin. Whether or not basal skeletal muscle health contributes to the myokine response to Whole body vibration (WBV), an exercise mimetic, has yet to be elucidated.METHODSData from Sixty-three young adults (32.5± 0.7 years, 57.1% female, 42.9% non-Hispanic Black) were included from a longitudinal twin cohort study. Skeletal muscle oxidative capacity (SMOC) was determined using near-infrared spectroscopy by measuring the rate of skeletal muscle oxygen consumption after stimulation and was represented as a rate constant averaged over three trials (AvgRC). The acute WBV protocol consisted of 10 cycles of 1 min of vibration exercise followed by 30s of standing rest. Blood was collected at baseline (PRE), immediately post, and 1h, 3h, and 24h post WBV and myokine concentrations of IL-6, myostatin, and decorin were measured at each of these timepoints. Participants were divided into two groups by SMOC: low skeletal muscle oxidative capacity (AvgRC < 1.82) and high skeletal muscle oxidative capacity (AvgRC > 2.13).RESULTSParticipant characteristics including age, BMI, body fat percentage, handgrip, and skeletal muscle index (SMI) were similar between groups. SMOC was positively associated with myostatin at baseline (ß= 564.6, SE=232.4, p=0.045) and 24H following WBV (ß= 661.0, SE=189.4, p=0.029). In addition, a significantly higher overall myostatin (p=0.026) and IL-6 response (p=0.001) to WBV was observed in in the high skeletal muscle oxidative capacity group when compared to the low skeletal muscle oxidative capacity group.CONCLUSIONSHigher skeletal muscle oxidative capacity is associated with a greater myostatin and IL-6 response to acute WBV. These data suggest that a higher SMOC at baseline may positively impact the myokine response to WBV, independent of adiposity, and demonstrates the importance of skeletal muscle health on preventing and ameliorating chronic disease.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"101 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145203561","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}
INTRODUCTIONAlthough the health benefits of exercise are well-documented, intense exercise can induce gastrointestinal symptoms, potentially due to disruption of the intestinal barrier. This disruption allows foreign substances to enter the intestine and circulation, triggering immune system activation and inflammation. In this study, we investigated the effects of a single bout of running exercise at different intensities on intestinal permeability and systemic immune cell responses.METHODSMale C57BL/6J mice were assigned to a control group, a low-intensity exercise group (10 m/min, Ex-low), and a high-intensity exercise group (20 m/min, Ex-high). The exercise lasted 60 min, while the control group remained sedentary. Immediately after exercise, intestinal permeability was assessed using FITC-Dextran. Immune cells were isolated from the lungs, blood, small intestinal lamina propria (siLP), and large intestinal lamina propria (liLP), while neutrophils, macrophages, eosinophils, B cells, and T cells were quantified by flow cytometry.RESULTSThe Ex-high group exhibited significantly increased intestinal permeability and neutrophil infiltration in the siLP compared with both the control and Ex-low groups. No significant differences in other immune cell types were observed between the groups. Furthermore, the Ex-high group demonstrated elevated neutrophil counts in the liLP, lungs, and blood. The expression of inflammatory cytokines (Il-1β and Il-6) and chemokines (Cxcl1 and Cxcl2) was also significantly higher in the small intestines of the Ex-high group.CONCLUSIONSA single bout of high-intensity exercise increases intestinal permeability and neutrophil infiltration in both the intestines and systemic tissues, highlighting a potential mechanism by which intense exercise induces intestinal and systemic inflammation.
{"title":"A Single Bout of High-Intensity Running Exercise Transiently and Reversibly Increases Intestinal Permeability and Neutrophil Recruitment in the Mouse Intestine.","authors":"Saki Kondo,Takahiro Nagatake,Koji Hosomi,Yoko Tojima,Kei Ishida,Azusa Saika,Jun Kunisawa","doi":"10.1249/mss.0000000000003858","DOIUrl":"https://doi.org/10.1249/mss.0000000000003858","url":null,"abstract":"INTRODUCTIONAlthough the health benefits of exercise are well-documented, intense exercise can induce gastrointestinal symptoms, potentially due to disruption of the intestinal barrier. This disruption allows foreign substances to enter the intestine and circulation, triggering immune system activation and inflammation. In this study, we investigated the effects of a single bout of running exercise at different intensities on intestinal permeability and systemic immune cell responses.METHODSMale C57BL/6J mice were assigned to a control group, a low-intensity exercise group (10 m/min, Ex-low), and a high-intensity exercise group (20 m/min, Ex-high). The exercise lasted 60 min, while the control group remained sedentary. Immediately after exercise, intestinal permeability was assessed using FITC-Dextran. Immune cells were isolated from the lungs, blood, small intestinal lamina propria (siLP), and large intestinal lamina propria (liLP), while neutrophils, macrophages, eosinophils, B cells, and T cells were quantified by flow cytometry.RESULTSThe Ex-high group exhibited significantly increased intestinal permeability and neutrophil infiltration in the siLP compared with both the control and Ex-low groups. No significant differences in other immune cell types were observed between the groups. Furthermore, the Ex-high group demonstrated elevated neutrophil counts in the liLP, lungs, and blood. The expression of inflammatory cytokines (Il-1β and Il-6) and chemokines (Cxcl1 and Cxcl2) was also significantly higher in the small intestines of the Ex-high group.CONCLUSIONSA single bout of high-intensity exercise increases intestinal permeability and neutrophil infiltration in both the intestines and systemic tissues, highlighting a potential mechanism by which intense exercise induces intestinal and systemic inflammation.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145203558","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 : 2025-09-25DOI: 10.1249/mss.0000000000003853
Mikel R Joachim,Althea Foster,Keith A Knurr,Stephanie A Kliethermes,Daniel G Cobian
PURPOSEThis study aimed to describe normative lower-extremity kinematic and kinetic asymmetries in healthy athletes for commonly measured variables during a countermovement jump (CMJ) and to investigate the effect of sport and sex on these asymmetries.METHODSRoutinely collected CMJ data were analyzed from healthy Division I collegiate athletes from 5 sports (cross country, track, soccer, basketball, and American football) with no history of lower extremity surgery or recent lower extremity injury. Between-limb asymmetries were calculated for vertical ground reaction forces and sagittal plane joint excursions, joint moment impulses, and joint work during the braking, concentric, and landing phases of the CMJ. Separate multivariable linear regression models assessed associations between sex, sport, and asymmetry for each variable.RESULTSData from 320 athletes were included (age: 19.2±1.2 years, males: 52%). Asymmetry magnitudes differed depending on the variable measured: Force-derived variable asymmetries ranged from 2-8%, joint excursion asymmetries were 1-6°, joint moment impulse asymmetries were 4-14%, and joint work asymmetries were 5-17%. Joint excursion asymmetries were greatest at the ankle and joint kinetic asymmetries were greatest at the knee. Sex and sport differences were observed but the magnitudes of these differences were minimal and unlikely to be clinically meaningful.CONCLUSIONSBetween-limb asymmetries varied from 2%-17% in healthy collegiate athletes, depending on the metric of interest; however, magnitude of observed asymmetries did not vary meaningfully between males and females or between sports. Variable-specific asymmetries from this study can be used by sports medicine and athletic performance practitioners to identify individuals who exhibit abnormal magnitudes of asymmetry or to assess the recovery of CMJ symmetry following injury or surgery.
{"title":"Lower Extremity Kinematic and Kinetic Asymmetries during Countermovement Jumps in Healthy Division I Collegiate Athletes.","authors":"Mikel R Joachim,Althea Foster,Keith A Knurr,Stephanie A Kliethermes,Daniel G Cobian","doi":"10.1249/mss.0000000000003853","DOIUrl":"https://doi.org/10.1249/mss.0000000000003853","url":null,"abstract":"PURPOSEThis study aimed to describe normative lower-extremity kinematic and kinetic asymmetries in healthy athletes for commonly measured variables during a countermovement jump (CMJ) and to investigate the effect of sport and sex on these asymmetries.METHODSRoutinely collected CMJ data were analyzed from healthy Division I collegiate athletes from 5 sports (cross country, track, soccer, basketball, and American football) with no history of lower extremity surgery or recent lower extremity injury. Between-limb asymmetries were calculated for vertical ground reaction forces and sagittal plane joint excursions, joint moment impulses, and joint work during the braking, concentric, and landing phases of the CMJ. Separate multivariable linear regression models assessed associations between sex, sport, and asymmetry for each variable.RESULTSData from 320 athletes were included (age: 19.2±1.2 years, males: 52%). Asymmetry magnitudes differed depending on the variable measured: Force-derived variable asymmetries ranged from 2-8%, joint excursion asymmetries were 1-6°, joint moment impulse asymmetries were 4-14%, and joint work asymmetries were 5-17%. Joint excursion asymmetries were greatest at the ankle and joint kinetic asymmetries were greatest at the knee. Sex and sport differences were observed but the magnitudes of these differences were minimal and unlikely to be clinically meaningful.CONCLUSIONSBetween-limb asymmetries varied from 2%-17% in healthy collegiate athletes, depending on the metric of interest; however, magnitude of observed asymmetries did not vary meaningfully between males and females or between sports. Variable-specific asymmetries from this study can be used by sports medicine and athletic performance practitioners to identify individuals who exhibit abnormal magnitudes of asymmetry or to assess the recovery of CMJ symmetry following injury or surgery.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145188758","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}
OBJECTIVESTo compare brain MRI outcomes between children who play American football vs non-contact sport controls testing the hypotheses that history (primary) and duration (secondary) of football participation would be associated with differences in cortical thickness, subcortical volume, resting state functional connectivity, and white matter diffusivity.METHODSThis secondary analysis of cross-sectional baseline data from the Adolescent Brain Cognitive Development (ABCD) Study compared brain MRI outcomes between 9-10 year-old children who play American football (n=1194) vs. non-contact sport controls (n=807). Outcomes included 74 bilateral cortical thickness regions; 10 gray matter subcortical volumes, with a priori focus on the hippocampi; resting-state functional connectivity (169 network-network correlations and 247 network-region correlations across 13 resting-state functional networks and 19 regions); and 21 diffusion tensor measures.RESULTSFootball participation was associated with global effects on cortical thickness (p=0.017), network-to-network resting state connectivity (p=0.010), and fiber tract volume (FDR-adjusted p=0.015) in primary analysis, but the only significant post-hoc finding after FDR correction was smaller cortical thickness adjacent to the left anterior transverse collateral sulcus in the football group (Cohen D=-0.258, FDR-adjusted p=0.017). There were no significant duration of football play effects in secondary analyses (all p>0.05). Targeted analysis of hippocampal volumes yielded no significant football or duration of play results (both p>0.05), but suggested a potential trend of lower hippocampal volumes with increasing duration of play.CONCLUSIONSAt ages 9-10, participation in American football was associated with minimal differences across a large array of structural, functional, and diffusion tensor MRI outcomes. While the clinical implications of these cross-sectional results are unknown, they merit additional investigation and can contribute to the ongoing discussion surrounding contact sport participation in children.
{"title":"A Comparison of Brain MRI Outcomes in Youth American Football versus Non-Contact Sport Athletes.","authors":"Yuanzhi Li,Chia-Hao Shih,Ingrid Ichesco,Andrea Almeida,Eleanna Varangis,Andrew Lorincz,Xuming He,James Eckner,Eric Ichesco","doi":"10.1249/mss.0000000000003856","DOIUrl":"https://doi.org/10.1249/mss.0000000000003856","url":null,"abstract":"OBJECTIVESTo compare brain MRI outcomes between children who play American football vs non-contact sport controls testing the hypotheses that history (primary) and duration (secondary) of football participation would be associated with differences in cortical thickness, subcortical volume, resting state functional connectivity, and white matter diffusivity.METHODSThis secondary analysis of cross-sectional baseline data from the Adolescent Brain Cognitive Development (ABCD) Study compared brain MRI outcomes between 9-10 year-old children who play American football (n=1194) vs. non-contact sport controls (n=807). Outcomes included 74 bilateral cortical thickness regions; 10 gray matter subcortical volumes, with a priori focus on the hippocampi; resting-state functional connectivity (169 network-network correlations and 247 network-region correlations across 13 resting-state functional networks and 19 regions); and 21 diffusion tensor measures.RESULTSFootball participation was associated with global effects on cortical thickness (p=0.017), network-to-network resting state connectivity (p=0.010), and fiber tract volume (FDR-adjusted p=0.015) in primary analysis, but the only significant post-hoc finding after FDR correction was smaller cortical thickness adjacent to the left anterior transverse collateral sulcus in the football group (Cohen D=-0.258, FDR-adjusted p=0.017). There were no significant duration of football play effects in secondary analyses (all p>0.05). Targeted analysis of hippocampal volumes yielded no significant football or duration of play results (both p>0.05), but suggested a potential trend of lower hippocampal volumes with increasing duration of play.CONCLUSIONSAt ages 9-10, participation in American football was associated with minimal differences across a large array of structural, functional, and diffusion tensor MRI outcomes. While the clinical implications of these cross-sectional results are unknown, they merit additional investigation and can contribute to the ongoing discussion surrounding contact sport participation in children.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"199 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145188786","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 : 2025-09-08DOI: 10.1249/mss.0000000000003842
Scott H Gillham,Paige L Cole,Daniel J Owens,Neil Chester,Theodoros M Bampouras,Danielle McCartney,Rebecca Gordon,Iain S McGregor,Graeme L Close
BACKGROUNDCannabidiol (CBD), a non-intoxicating phytocannabinoid, is used by athletes to enhance recovery and manage other conditions (e.g., poor sleep, anxiety). Although CBD is not prohibited by the World Anti-Doping Agency (WADA), other cannabinoids found in "broad-spectrum" CBD products (e.g., cannabigerol (CBG), cannabidivarin (CBDV)), remain prohibited.OBJECTIVESThis study aimed to determine whether 10-weeks' use of a broad-spectrum CBD product (150 mg.day [containing trace concentrations of CBG]) could lead to detectable concentrations of prohibited cannabinoids in urine and plasma. The influence of moderate-intensity exercise was also assessed.METHODSThirty-six healthy individuals (47% male) self-administered either a broad-spectrum CBD product (n = 31; CBD) or a visually identical placebo (n = 5; PLA) for 10-weeks. After 10-weeks, participants completed a fasted, 90-minute bout of moderate-intensity exercise (55% VO2peak). Blood and urine samples were collected at baseline (pre-supplementation) and pre- and post-exercise.RESULTSNo cannabinoids or metabolites were detected at baseline in either the PLA or CBD group. Following 10-weeks of supplementation, urinary concentrations of CBD and its metabolites (6-OH-CBD, 7-COOH-CBD, 7-OH-CBD) were present. CBG and CBDV were also detected in 42% and 68% of pre-exercise samples, respectively. Urinary concentrations of 6-OH-CBD (P = 0.006), 7-OH-CBD (P = 0.009), CBD (P = 0.043), CBG (P = 0.0023) and CBDV (P = 0.033) also increased from pre- to post-exercise. CBG and CBDV were detected in 74% and 84% of post-exercise samples, respectively. Concentrations of ∆9-THC or its metabolites (11-OH-THC, 11-COOH-THC) were not present at any timepoint.CONCLUSIONSDaily use of a broad-spectrum CBD supplement resulted in detectable urinary concentrations of WADA-prohibited cannabinoids in urine. Exercise appeared to increase concentrations of these cannabinoids. Therefore, athletes should avoid consuming broad-spectrum CBD products, given the potential associated anti-doping risks.
{"title":"Daily Use of a Broad-Spectrum Cannabidiol Supplement Produces Detectable Concentrations of Cannabinoids in Urine Prohibited by the World Anti-Doping Agency: An Effect Amplified by Exercise.","authors":"Scott H Gillham,Paige L Cole,Daniel J Owens,Neil Chester,Theodoros M Bampouras,Danielle McCartney,Rebecca Gordon,Iain S McGregor,Graeme L Close","doi":"10.1249/mss.0000000000003842","DOIUrl":"https://doi.org/10.1249/mss.0000000000003842","url":null,"abstract":"BACKGROUNDCannabidiol (CBD), a non-intoxicating phytocannabinoid, is used by athletes to enhance recovery and manage other conditions (e.g., poor sleep, anxiety). Although CBD is not prohibited by the World Anti-Doping Agency (WADA), other cannabinoids found in \"broad-spectrum\" CBD products (e.g., cannabigerol (CBG), cannabidivarin (CBDV)), remain prohibited.OBJECTIVESThis study aimed to determine whether 10-weeks' use of a broad-spectrum CBD product (150 mg.day [containing trace concentrations of CBG]) could lead to detectable concentrations of prohibited cannabinoids in urine and plasma. The influence of moderate-intensity exercise was also assessed.METHODSThirty-six healthy individuals (47% male) self-administered either a broad-spectrum CBD product (n = 31; CBD) or a visually identical placebo (n = 5; PLA) for 10-weeks. After 10-weeks, participants completed a fasted, 90-minute bout of moderate-intensity exercise (55% VO2peak). Blood and urine samples were collected at baseline (pre-supplementation) and pre- and post-exercise.RESULTSNo cannabinoids or metabolites were detected at baseline in either the PLA or CBD group. Following 10-weeks of supplementation, urinary concentrations of CBD and its metabolites (6-OH-CBD, 7-COOH-CBD, 7-OH-CBD) were present. CBG and CBDV were also detected in 42% and 68% of pre-exercise samples, respectively. Urinary concentrations of 6-OH-CBD (P = 0.006), 7-OH-CBD (P = 0.009), CBD (P = 0.043), CBG (P = 0.0023) and CBDV (P = 0.033) also increased from pre- to post-exercise. CBG and CBDV were detected in 74% and 84% of post-exercise samples, respectively. Concentrations of ∆9-THC or its metabolites (11-OH-THC, 11-COOH-THC) were not present at any timepoint.CONCLUSIONSDaily use of a broad-spectrum CBD supplement resulted in detectable urinary concentrations of WADA-prohibited cannabinoids in urine. Exercise appeared to increase concentrations of these cannabinoids. Therefore, athletes should avoid consuming broad-spectrum CBD products, given the potential associated anti-doping risks.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145018059","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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