Pub Date : 2026-01-23DOI: 10.1249/mss.0000000000003941
Christian J Brakenridge,Hayley Dillon,Dulari Hakamuwalekamlage,Neville Owen,David W Dunstan,Brigid M Lynch,Nicholas J Saner,Agus Salim,Erin J Howden
INTRODUCTIONWe compared 16-week wearable activity monitor trajectories of patients receiving hematopoietic stem-cell transplants (SCT) engaged in an activity intervention trial.METHODSForty adults with haematological malignancy scheduled to undergo SCT were randomised to an exercise and sedentary behaviour intervention (INT; n = 22) or usual care (UC; n = 19). Participants were observed continuously for the duration of inpatient hospitalisation for SCT (approximately 4 weeks) and outpatient (12 weeks) care. Between-group differences were determined by 16-week trajectories of Fitbit-derived variables of physical activity and sedentary time (ST).RESULTSInpatient hospitalisation for SCT led to higher levels of ST and lower levels of physical activity in both groups relative to pre-admission. Across the ~16-week period, the INT group had significantly higher physical activity and lower ST. During the 16-week study period and independent of intervention group assignment, a higher pre-hospitalisation cardiorespiratory fitness was associated with higher levels of moderate-to-vigorous intensity physical activity, being female had stronger associations with step counts, older age and myeloablative SCT were associated with higher ST, and higher proportions of lean mass were associated with higher levels of LPA.CONCLUSIONSWearable activity monitors can continuously assess the behavioural impacts of SCT and the efficacy of activity intervention in patients receiving hospital treatment for haematological malignancy. Tracker data showed that the activity intervention protected against declines in physical activity and increases in sedentary time with usual hospital care in SCT. Higher pre-hospitalisation cardiorespiratory fitness and proportion of lean mass were associated with preservation and recuperation of activity levels.
在一项活动干预试验中，我们比较了接受造血干细胞移植（SCT）的患者16周的可穿戴活动监测轨迹。方法40例计划接受SCT的成人恶性血液肿瘤患者随机分为运动和久坐行为干预组（INT, n = 22）或常规护理组（UC, n = 19）。参与者在SCT住院（约4周）和门诊（12周）治疗期间连续观察。组间差异由fitbit衍生的身体活动变量和久坐时间（ST）的16周轨迹确定。结果与入院前相比，两组患者因SCT住院导致ST水平升高和身体活动水平降低。在16周的研究期间，独立于干预组分配，较高的住院前心肺健康与较高的中等至高强度体力活动水平相关，女性与步数有更强的关联，年龄较大和清骨髓SCT与较高的ST相关。瘦肉比例越高，LPA水平越高。结论可穿戴活动监测仪可连续评估SCT对住院治疗血液系统恶性肿瘤患者的行为影响和活动干预的效果。追踪数据显示，活动干预可以防止SCT患者在常规医院护理下身体活动减少和久坐时间增加。较高的住院前心肺适能和瘦体重比例与活动水平的保存和恢复有关。
{"title":"Stem Cell Transplant Patients' Activity Decline, Outpatient Resumption and Intervention Effectiveness Identified by Wearable Activity Monitoring.","authors":"Christian J Brakenridge,Hayley Dillon,Dulari Hakamuwalekamlage,Neville Owen,David W Dunstan,Brigid M Lynch,Nicholas J Saner,Agus Salim,Erin J Howden","doi":"10.1249/mss.0000000000003941","DOIUrl":"https://doi.org/10.1249/mss.0000000000003941","url":null,"abstract":"INTRODUCTIONWe compared 16-week wearable activity monitor trajectories of patients receiving hematopoietic stem-cell transplants (SCT) engaged in an activity intervention trial.METHODSForty adults with haematological malignancy scheduled to undergo SCT were randomised to an exercise and sedentary behaviour intervention (INT; n = 22) or usual care (UC; n = 19). Participants were observed continuously for the duration of inpatient hospitalisation for SCT (approximately 4 weeks) and outpatient (12 weeks) care. Between-group differences were determined by 16-week trajectories of Fitbit-derived variables of physical activity and sedentary time (ST).RESULTSInpatient hospitalisation for SCT led to higher levels of ST and lower levels of physical activity in both groups relative to pre-admission. Across the ~16-week period, the INT group had significantly higher physical activity and lower ST. During the 16-week study period and independent of intervention group assignment, a higher pre-hospitalisation cardiorespiratory fitness was associated with higher levels of moderate-to-vigorous intensity physical activity, being female had stronger associations with step counts, older age and myeloablative SCT were associated with higher ST, and higher proportions of lean mass were associated with higher levels of LPA.CONCLUSIONSWearable activity monitors can continuously assess the behavioural impacts of SCT and the efficacy of activity intervention in patients receiving hospital treatment for haematological malignancy. Tracker data showed that the activity intervention protected against declines in physical activity and increases in sedentary time with usual hospital care in SCT. Higher pre-hospitalisation cardiorespiratory fitness and proportion of lean mass were associated with preservation and recuperation of activity levels.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"195 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146021492","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 : 2026-01-23DOI: 10.1249/mss.0000000000003937
Katherine Boere,Nevan Young,Rae Dauphinee,Frances Copithorne,Brett S Kirby,Olave E Krigolson,Trent Stellingwerff
PURPOSEWe tested the hypothesis that marathon racing reduces working memory performance and increases frontal theta activity in trained female endurance athletes. We further examined whether changes in cognitive performance or brain activity were associated with either acute and/or chronic risk of low energy availability.METHODSSixteen female Tier 2 runners (42 ± 9 y; VO2max 45.6 ± 6 mL·kg-1·min-1) underwent VO2max testing and the Low Energy Availability in Females Questionnaire (LEAF-Q) 7-14 days prior to a Marathon. Participants completed 1-back (low load) and 3-back (high load) working memory tasks during electroencephalogram (EEG) recordings, performed before and immediately after the race (<10 mins). Accuracy and reaction time measured cognitive performance, and frontal theta power measured cognitive effort.RESULTSSixteen runners completed the marathon in 4:16 ± 37 min (70 ± 6% VO2max), with a mean carbohydrate intake of 28 ± 14 g/hr. Six athletes exceeded the LEAF-Q threshold (>=8) and eight reported menstrual dysfunction. Post-race, 3-back accuracy declined (-18.8%, p =.003) while reaction time shortened for both task versions (5.3-6.6%, p =.002). Frontal theta increased post-race (1-back: +26.8%; 3-back: +29.6%, p <.001). Regression models showed 3-back accuracy changes were predicted by LEAF-Q score (β = 0.494, p =.016). In contrast, theta increases were predicted by a combination of lower carbohydrate intake (β = -0.025, p =.005), longer race time (β = 0.008, p =.005), and higher LEAF-Q score (β = 0.121, p <.001).CONCLUSIONSWorking memory performance is reduced and cognitive effort is increased after marathon racing in trained female athletes. These effects are linked to both acute and chronic risk of low energy availability, emphasizing the need for individualized fueling strategies to preserve cognitive performance during endurance events.
目的：我们对马拉松比赛降低训练有素的女性耐力运动员的工作记忆表现并增加额叶θ波活动的假设进行了验证。我们进一步研究了认知表现或大脑活动的变化是否与急性和/或慢性低能量可用性风险相关。方法16名女性二级运动员（42±9 y; VO2max 45.6±6 mL·kg-1·min-1）在马拉松比赛前7-14天进行VO2max测试和女性低能量利用率问卷（LEAF-Q）。参与者在比赛前和比赛后完成了1-back（低负荷）和3-back（高负荷）的工作记忆任务（=8），其中8人报告了月经功能障碍。比赛后，3-back准确度下降（-18.8%,p = 0.003），而两个任务版本的反应时间缩短（5.3-6.6%,p = 0.002）。额叶theta在比赛后增加（1-back: +26.8%; 3-back: +29.6%, p < 0.001）。回归模型显示，LEAF-Q评分预测3-back准确度变化（β = 0.494, p = 0.016）。相比之下，较低碳水化合物摄入量（β = -0.025, p = 0.005）、较长的比赛时间（β = 0.008, p = 0.005）和较高的LEAF-Q评分（β = 0.121, p < 0.001）均可预测theta增加。结论训练后的女运动员参加马拉松比赛后工作记忆能力下降，认知能力提高。这些影响与急性和慢性低能量可用性风险有关，强调需要个性化的加油策略来保持耐力比赛中的认知表现。
{"title":"Working Memory Performance is Reduced Following a Marathon Race and Associated with Low Energy Availability in Females.","authors":"Katherine Boere,Nevan Young,Rae Dauphinee,Frances Copithorne,Brett S Kirby,Olave E Krigolson,Trent Stellingwerff","doi":"10.1249/mss.0000000000003937","DOIUrl":"https://doi.org/10.1249/mss.0000000000003937","url":null,"abstract":"PURPOSEWe tested the hypothesis that marathon racing reduces working memory performance and increases frontal theta activity in trained female endurance athletes. We further examined whether changes in cognitive performance or brain activity were associated with either acute and/or chronic risk of low energy availability.METHODSSixteen female Tier 2 runners (42 ± 9 y; VO2max 45.6 ± 6 mL·kg-1·min-1) underwent VO2max testing and the Low Energy Availability in Females Questionnaire (LEAF-Q) 7-14 days prior to a Marathon. Participants completed 1-back (low load) and 3-back (high load) working memory tasks during electroencephalogram (EEG) recordings, performed before and immediately after the race (<10 mins). Accuracy and reaction time measured cognitive performance, and frontal theta power measured cognitive effort.RESULTSSixteen runners completed the marathon in 4:16 ± 37 min (70 ± 6% VO2max), with a mean carbohydrate intake of 28 ± 14 g/hr. Six athletes exceeded the LEAF-Q threshold (>=8) and eight reported menstrual dysfunction. Post-race, 3-back accuracy declined (-18.8%, p =.003) while reaction time shortened for both task versions (5.3-6.6%, p =.002). Frontal theta increased post-race (1-back: +26.8%; 3-back: +29.6%, p <.001). Regression models showed 3-back accuracy changes were predicted by LEAF-Q score (β = 0.494, p =.016). In contrast, theta increases were predicted by a combination of lower carbohydrate intake (β = -0.025, p =.005), longer race time (β = 0.008, p =.005), and higher LEAF-Q score (β = 0.121, p <.001).CONCLUSIONSWorking memory performance is reduced and cognitive effort is increased after marathon racing in trained female athletes. These effects are linked to both acute and chronic risk of low energy availability, emphasizing the need for individualized fueling strategies to preserve cognitive performance during endurance events.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"69 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146021497","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 : 2026-01-23DOI: 10.1249/mss.0000000000003940
Ricardo J Rodrigues,Paolo M Cunha,João P Nunes,Arthur Eumann Mesas,Crivaldo G Cardoso,Décio S Barbosa,Patricia C Brum,José Maria Santarém,Rodrigo R Fernandes,Paulo Sugihara,Aline Prado,Ligia C Coelho Comar,Melissa Antunes,Luis C Miguita Junior,Gabriela Arfelli Bragatto,Elaine Batistella,Danielle Venturini,Luís B Sardinha,Lauro C Vianna,Edilson S Cyrino
PURPOSEThis randomized controlled trial investigated the effects of a supervised progressive resistance training (RT) program conducted over two years on cardiac structure and function in older women.METHODSSixty-four physically independent older women (≥ 60 years) were recruited for this investigation. Participants were randomly assigned to either a training group (TG, n = 33) or a control group (CG, n = 31). The RT program was conducted over two years, in three sessions per week, on nonconsecutive days, and included eight whole-body exercises performed in three sets of 8-12 repetitions. Echocardiographic assessments were performed both before and after a two-year period by an experienced echocardiographer who was blinded to the participant's status and group assignment.RESULTSA group-by-time interaction was found (P < 0.05) for the left ventricular mass index (TG = -5.5% vs. CG = +11%), septal thickness (TG = -3.8% vs. CG = +7.3%), posterior wall thickness (TG = -2.8% vs. CG = +13.6%), left ventricular end-diastolic volume (TG = -9.0% vs. CG = +20.0%), left ventricular end-systolic volume (TG = -7.8% vs. CG = +23.3%), left atrial volume index (TG = -7.1% vs. CG = +28,1%), the left ventricular ejection fraction (TG = -1.0% vs. CG = -4.9%), the E'/E septal (TG = -11.0% vs. CG = +22.1%), the E septal (TG = +14.9% vs. CG = -19.2%), and the E lateral (TG = +12.7% vs. CG = -22.8%).CONCLUSIONSOur results suggest that a two-year follow-up of the RT intervention may improve both the cardiac morphological and functional parameters in older women.
{"title":"Long-Term Resistance Training Improves Cardiac Structure and Function in Older Women: A Two-Year Randomized Controlled Trial.","authors":"Ricardo J Rodrigues,Paolo M Cunha,João P Nunes,Arthur Eumann Mesas,Crivaldo G Cardoso,Décio S Barbosa,Patricia C Brum,José Maria Santarém,Rodrigo R Fernandes,Paulo Sugihara,Aline Prado,Ligia C Coelho Comar,Melissa Antunes,Luis C Miguita Junior,Gabriela Arfelli Bragatto,Elaine Batistella,Danielle Venturini,Luís B Sardinha,Lauro C Vianna,Edilson S Cyrino","doi":"10.1249/mss.0000000000003940","DOIUrl":"https://doi.org/10.1249/mss.0000000000003940","url":null,"abstract":"PURPOSEThis randomized controlled trial investigated the effects of a supervised progressive resistance training (RT) program conducted over two years on cardiac structure and function in older women.METHODSSixty-four physically independent older women (≥ 60 years) were recruited for this investigation. Participants were randomly assigned to either a training group (TG, n = 33) or a control group (CG, n = 31). The RT program was conducted over two years, in three sessions per week, on nonconsecutive days, and included eight whole-body exercises performed in three sets of 8-12 repetitions. Echocardiographic assessments were performed both before and after a two-year period by an experienced echocardiographer who was blinded to the participant's status and group assignment.RESULTSA group-by-time interaction was found (P < 0.05) for the left ventricular mass index (TG = -5.5% vs. CG = +11%), septal thickness (TG = -3.8% vs. CG = +7.3%), posterior wall thickness (TG = -2.8% vs. CG = +13.6%), left ventricular end-diastolic volume (TG = -9.0% vs. CG = +20.0%), left ventricular end-systolic volume (TG = -7.8% vs. CG = +23.3%), left atrial volume index (TG = -7.1% vs. CG = +28,1%), the left ventricular ejection fraction (TG = -1.0% vs. CG = -4.9%), the E'/E septal (TG = -11.0% vs. CG = +22.1%), the E septal (TG = +14.9% vs. CG = -19.2%), and the E lateral (TG = +12.7% vs. CG = -22.8%).CONCLUSIONSOur results suggest that a two-year follow-up of the RT intervention may improve both the cardiac morphological and functional parameters in older women.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146021568","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 : 2025-12-23DOI: 10.1249/mss.0000000000003931
María Romero-Elías,David García-González,Isabel Esteban Bosque,Violeta Suarez Blázquez,Esther J Vielba,Marta Méndez-Otero,Alberto Pueyo Rabanal,Matías Cea Soriano,Ana Ruiz-Casado
BACKGROUNDPancreatic cancer (PC) is highly lethal, with surgery as the only curative option but significant postoperative morbidity. Prehabilitation shows promise in other cancers, yet no trials have examined supervised exercise during neoadjuvant chemotherapy in PC.OBJECTIVESThe primary objective was to evaluate recruitment and adherence to a trimodal prehabilitation program during neoadjuvant chemotherapy in patients with non-metastatic PC. Secondary aims included assessing changes in physical condition, fatigue, quality of life (QoL) and some biomarkers.METHODSA prospective single-center study recruited adults diagnosed with non-metastatic PC scheduled for chemotherapy. Inclusion criteria were ECOG 0-2 and the ability to perform the one mile walk test. The intervention involved supervised exercise, respiratory muscle training, nutritional counselling, and psychological support. Primary outcomes were recruitment (10 patients/year) and adherence (≥70% of exercise, nutrition, or psychological sessions). Secondary outcomes included cardiorespiratory fitness (6-minute walking test [6MWT], mile time walk test, estimated VO₂peak), muscular strength (sit-to-stand [5STS] test and handgrip), global QoL (EORTC QLQ-C30), fatigue (PERFORM and FACIT), and body composition (body mass index (BMI)).RESULTSAmong 35 screened patients, 14 completed the prehabilitation program and 12 underwent surgery (in 30 months). 10 patients were recruited in 12 months. Adherence was acceptable across all components, with physical training achieving 100% attendance. Significant improvements were observed in respiratory capacity (p=0.000), gait speed (p=0.001), estimated VO₂peak (p=0.002), 6MWT (p=0.021), one mile walk test (p=0.000), 5STS (p=0.000), BMI (p=0.047), fatigue PERFORM (p=0.023) and FACIT (p=0.000), and QoL (p=0.017).CONCLUSIONSTrimodal prehabilitation during neoadjuvant chemotherapy in PC can be implemented and may be associated with clinically meaningful improvements in physical fitness, fatigue, and QoL. Multicenter randomized controlled trials are warranted to determine its impact on postoperative outcomes.
{"title":"Trimodal Prehabilitation with Supervised Exercise During Neoadjuvant Chemotherapy in Localized Pancreatic Cancer.","authors":"María Romero-Elías,David García-González,Isabel Esteban Bosque,Violeta Suarez Blázquez,Esther J Vielba,Marta Méndez-Otero,Alberto Pueyo Rabanal,Matías Cea Soriano,Ana Ruiz-Casado","doi":"10.1249/mss.0000000000003931","DOIUrl":"https://doi.org/10.1249/mss.0000000000003931","url":null,"abstract":"BACKGROUNDPancreatic cancer (PC) is highly lethal, with surgery as the only curative option but significant postoperative morbidity. Prehabilitation shows promise in other cancers, yet no trials have examined supervised exercise during neoadjuvant chemotherapy in PC.OBJECTIVESThe primary objective was to evaluate recruitment and adherence to a trimodal prehabilitation program during neoadjuvant chemotherapy in patients with non-metastatic PC. Secondary aims included assessing changes in physical condition, fatigue, quality of life (QoL) and some biomarkers.METHODSA prospective single-center study recruited adults diagnosed with non-metastatic PC scheduled for chemotherapy. Inclusion criteria were ECOG 0-2 and the ability to perform the one mile walk test. The intervention involved supervised exercise, respiratory muscle training, nutritional counselling, and psychological support. Primary outcomes were recruitment (10 patients/year) and adherence (≥70% of exercise, nutrition, or psychological sessions). Secondary outcomes included cardiorespiratory fitness (6-minute walking test [6MWT], mile time walk test, estimated VO₂peak), muscular strength (sit-to-stand [5STS] test and handgrip), global QoL (EORTC QLQ-C30), fatigue (PERFORM and FACIT), and body composition (body mass index (BMI)).RESULTSAmong 35 screened patients, 14 completed the prehabilitation program and 12 underwent surgery (in 30 months). 10 patients were recruited in 12 months. Adherence was acceptable across all components, with physical training achieving 100% attendance. Significant improvements were observed in respiratory capacity (p=0.000), gait speed (p=0.001), estimated VO₂peak (p=0.002), 6MWT (p=0.021), one mile walk test (p=0.000), 5STS (p=0.000), BMI (p=0.047), fatigue PERFORM (p=0.023) and FACIT (p=0.000), and QoL (p=0.017).CONCLUSIONSTrimodal prehabilitation during neoadjuvant chemotherapy in PC can be implemented and may be associated with clinically meaningful improvements in physical fitness, fatigue, and QoL. Multicenter randomized controlled trials are warranted to determine its impact on postoperative outcomes.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145807546","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 : 2025-12-23DOI: 10.1249/mss.0000000000003932
William S Zoughaib,Madison J Fry,Ahaan Singhal,Richard L Hoffman,Andrew R Coggan
INTRODUCTION/PURPOSEIncreasing nitric oxide bioavailability via nitrate (NO3-) ingestion enhances muscle contractility, which may be due to phosphorylation of the regulatory light chain (RLC) of myosin. If so, there should be an interaction between NO3- supplementation and post-activation twitch potentiation, which acts via the same pathway.METHODSA double-blind, placebo-controlled, randomized crossover study was conducted to determine the influence of dietary NO3- on the contractile properties of the triceps brachii (60-70% fast-twitch, or type II) and triceps surae (60-70% slow-twitch, or type I) muscles of healthy young men (n=14). Participants were studied after acute ingestion of 2.2 mL/kg of beetroot juice either containing or lacking 200 µmol/kg of NO3-, with neuromuscular electrical stimulation used to determine muscle function.RESULTSNO3- supplementation did not alter unpotentiated or potentiated peak twitch torque or the maximal rates of torque development or relaxation in either muscle group. On the other hand, NO3- ingestion resulted in significant changes in the torque-frequency relationship of both the triceps brachii (P=0.019) and the triceps surae (P<0.001). This was due to a leftward shift of this sigmoidal relationship in the triceps brachii, but a rightward shift in the triceps surae.CONCLUSIONSWe conclude that dietary NO3- has opposing effects on the contractile properties of fast and slow human muscles, which could be due to differential changes in Ca2+ sensitivity. However, potentiation was unaltered, suggesting that this occurs independently of changes in RLC phosphorylation. Additional research will be required to determine the underlying biochemical mechanisms.
{"title":"Opposing Effects of Dietary Nitrate on Muscle Contractile Function in Fast and Slow Human Muscles.","authors":"William S Zoughaib,Madison J Fry,Ahaan Singhal,Richard L Hoffman,Andrew R Coggan","doi":"10.1249/mss.0000000000003932","DOIUrl":"https://doi.org/10.1249/mss.0000000000003932","url":null,"abstract":"INTRODUCTION/PURPOSEIncreasing nitric oxide bioavailability via nitrate (NO3-) ingestion enhances muscle contractility, which may be due to phosphorylation of the regulatory light chain (RLC) of myosin. If so, there should be an interaction between NO3- supplementation and post-activation twitch potentiation, which acts via the same pathway.METHODSA double-blind, placebo-controlled, randomized crossover study was conducted to determine the influence of dietary NO3- on the contractile properties of the triceps brachii (60-70% fast-twitch, or type II) and triceps surae (60-70% slow-twitch, or type I) muscles of healthy young men (n=14). Participants were studied after acute ingestion of 2.2 mL/kg of beetroot juice either containing or lacking 200 µmol/kg of NO3-, with neuromuscular electrical stimulation used to determine muscle function.RESULTSNO3- supplementation did not alter unpotentiated or potentiated peak twitch torque or the maximal rates of torque development or relaxation in either muscle group. On the other hand, NO3- ingestion resulted in significant changes in the torque-frequency relationship of both the triceps brachii (P=0.019) and the triceps surae (P<0.001). This was due to a leftward shift of this sigmoidal relationship in the triceps brachii, but a rightward shift in the triceps surae.CONCLUSIONSWe conclude that dietary NO3- has opposing effects on the contractile properties of fast and slow human muscles, which could be due to differential changes in Ca2+ sensitivity. However, potentiation was unaltered, suggesting that this occurs independently of changes in RLC phosphorylation. Additional research will be required to determine the underlying biochemical mechanisms.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145807545","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 : 2025-12-23DOI: 10.1249/mss.0000000000003930
Stephen P Allen,Alena M Grabowski
PURPOSEWe determined the biomechanical and metabolic effects of different prosthetic effective leg lengths with two types of protheses on lower-limb joint kinematics and kinetics, asymmetry, and net efficiency in cyclists with TTA.METHODS12 participants with TTA rode at 1.5 W kg-1 with their standard prosthetic effective leg length and +5, +10, and +15 mm using a daily-use prosthesis and CSP.RESULTS+15 mm prosthetic effective leg length decreased average knee joint angle by 3° for both prosthesis types (p=0.02), but did not alter kinematic or kinetic asymmetries, or net efficiency. However, use of a CSP versus daily-use prosthesis increased average knee joint angle of the affected side by 12.5° and decreased knee angle asymmetry from 11% to 3%. There were no changes to joint or crank power asymmetry, but net efficiency improved from 21.4% using a daily-use prosthesis to 22.3% using a CSP.CONCLUSIONSCyclists with a TTA can increase prosthetic effective leg length in a daily-use prosthesis or CSP up to 15 mm without affecting performance. However, use of a CSP decreases knee angle asymmetry and improves efficiency compared to a daily-use prosthesis. CSPs may shift knee extensor muscles into a more favorable region of the force-length relationship for producing force more economically. These findings can be used to inform bicycle and prosthesis designs that may encourage individuals with a TTA to increase exercise and sport participation.
目的研究两种类型的假体不同有效腿长对TTA自行车运动员下肢关节运动学和动力学、不对称性和净效率的生物力学和代谢影响。方法12名TTA患者在1.5 W kg-1时使用标准假体有效腿长，使用日常使用假体和CSP时使用+5、+10和+15 mm。结果+15 mm假体有效腿长使两种假体的平均膝关节角度降低3°（p=0.02），但没有改变运动学或动力学不对称，或净效率。然而，与日常使用的假体相比，使用CSP使患侧膝关节的平均角度增加了12.5°，并将膝关节角度不对称从11%降低到3%。关节或曲柄动力不对称没有改变，但净效率从使用日常假体的21.4%提高到使用CSP的22.3%。结论骑自行车者在日常使用的假体或CSP中，TTA可以增加假体的有效腿长达15mm，而不影响其表现。然而，与日常使用的假体相比，CSP的使用减少了膝关节角度的不对称，提高了效率。CSPs可以将膝关节伸肌转移到力-长度关系中更有利的区域，从而更经济地产生力。这些发现可用于指导自行车和假体的设计，以鼓励患有TTA的个体增加锻炼和运动参与。
{"title":"Mechanics and Energetics of Cycling with Unilateral Transtibial Amputation: Effects of Prosthetic Effective Leg Length and Prosthesis Type.","authors":"Stephen P Allen,Alena M Grabowski","doi":"10.1249/mss.0000000000003930","DOIUrl":"https://doi.org/10.1249/mss.0000000000003930","url":null,"abstract":"PURPOSEWe determined the biomechanical and metabolic effects of different prosthetic effective leg lengths with two types of protheses on lower-limb joint kinematics and kinetics, asymmetry, and net efficiency in cyclists with TTA.METHODS12 participants with TTA rode at 1.5 W kg-1 with their standard prosthetic effective leg length and +5, +10, and +15 mm using a daily-use prosthesis and CSP.RESULTS+15 mm prosthetic effective leg length decreased average knee joint angle by 3° for both prosthesis types (p=0.02), but did not alter kinematic or kinetic asymmetries, or net efficiency. However, use of a CSP versus daily-use prosthesis increased average knee joint angle of the affected side by 12.5° and decreased knee angle asymmetry from 11% to 3%. There were no changes to joint or crank power asymmetry, but net efficiency improved from 21.4% using a daily-use prosthesis to 22.3% using a CSP.CONCLUSIONSCyclists with a TTA can increase prosthetic effective leg length in a daily-use prosthesis or CSP up to 15 mm without affecting performance. However, use of a CSP decreases knee angle asymmetry and improves efficiency compared to a daily-use prosthesis. CSPs may shift knee extensor muscles into a more favorable region of the force-length relationship for producing force more economically. These findings can be used to inform bicycle and prosthesis designs that may encourage individuals with a TTA to increase exercise and sport participation.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"171 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145807543","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 : 2025-12-23DOI: 10.1249/mss.0000000000003928
Ran Bao,Levi Wade,Angus A Leahy,Mark R Beauchamp,Thierno M O Diallo,Jordan J Smith,Charles H Hillman,David R Lubans
PURPOSEThe aim of this study was to examine the mediating effects of cardiorespiratory and muscular fitness (the fitness hypothesis) and motor competence (the skill acquisition hypothesis) on executive functions among children participating in the Learning to Lead fundamental movement skills intervention.METHODSWe conducted a two-arm cluster randomized controlled trial in 20 primary schools in New South Wales, Australia (N = 946). Ten schools were allocated to the intervention condition and ten to the wait-list control condition. Children in the intervention condition participated in 12 x 30-minute peer-led fundamental movement skill sessions over a 10-week period. Cardiorespiratory fitness, muscular fitness, motor competence, inhibition, and cognitive flexibility were assessed at baseline and post-intervention. The pre-registered mediation analysis was conducted at the individual level within a structural equation modeling framework, using cluster-robust standard errors to account for non-independence of observations at the classroom level.RESULTSNone of the mediation effects were statistically significant. The intervention significantly improved inhibition (β = 0.125, SE = 0.054, p = 0.021), but not cognitive flexibility (β = 0.013, SE = 0.068, p = 0.845). The intervention improved cardiorespiratory fitness (β = 0.14, SE = 0.051, p = 0.007), but not muscular fitness (β = -0.02, SE = 0.062, p = 0.707) or motor competence (β = 0.04, SE = 0.076, p = 0.568). Muscular fitness was associated with inhibition (β = 0.13, SE = 0.035, p < 0.001), and motor competence was associated with inhibition (β = 0.08, SE = 0.034, p = 0.017) and cognitive flexibility (β = 0.12, SE = 0.030, p < 0.001) at post-intervention.CONCLUSIONSChanges in fitness and motor competence did not mediate the effect of the intervention on children's executive functions. However, the significant associations between mediators and executive functions offer partial support for both the 'fitness' and 'skill acquisition' hypotheses, suggesting their potential importance for children's cognitive development.
目的探讨心肺肌肉适能（适能假说）和运动能力（技能习得假说）对学习领导基本运动技能干预儿童执行功能的中介作用。方法在澳大利亚新南威尔士州20所小学进行双组随机对照试验（N = 946）。10所学校被分配到干预条件，10所学校被分配到等候名单控制条件。干预条件下的儿童在10周的时间内参加了12 x 30分钟的同伴指导的基本运动技能课程。在基线和干预后评估心肺健康、肌肉健康、运动能力、抑制和认知灵活性。预先登记的中介分析是在结构方程建模框架内的个人层面进行的，使用聚类鲁棒标准误差来解释课堂层面观察的非独立性。结果所有中介效应均无统计学意义。干预显著改善了抑制能力（β = 0.125, SE = 0.054, p = 0.021），但对认知灵活性没有改善（β = 0.013, SE = 0.068, p = 0.845）。干预改善了心肺功能（β = 0.14, SE = 0.051, p = 0.007），但没有改善肌肉功能（β = -0.02, SE = 0.062, p = 0.707）或运动能力（β = 0.04, SE = 0.076, p = 0.568）。干预后，肌肉健康与抑制相关（β = 0.13, SE = 0.035, p < 0.001），运动能力与抑制相关（β = 0.08, SE = 0.034, p = 0.017），认知灵活性相关（β = 0.12, SE = 0.030, p < 0.001）。结论健身和运动能力的改变并不是干预对儿童执行功能影响的中介。然而，中介和执行功能之间的显著关联为“适应性”和“技能习得”假说提供了部分支持，表明它们对儿童认知发展的潜在重要性。
{"title":"Mediating Effects of Fitness and Motor Competence on Children's Executive Functions: Findings from the Learning to Lead Cluster Randomized Controlled Trial.","authors":"Ran Bao,Levi Wade,Angus A Leahy,Mark R Beauchamp,Thierno M O Diallo,Jordan J Smith,Charles H Hillman,David R Lubans","doi":"10.1249/mss.0000000000003928","DOIUrl":"https://doi.org/10.1249/mss.0000000000003928","url":null,"abstract":"PURPOSEThe aim of this study was to examine the mediating effects of cardiorespiratory and muscular fitness (the fitness hypothesis) and motor competence (the skill acquisition hypothesis) on executive functions among children participating in the Learning to Lead fundamental movement skills intervention.METHODSWe conducted a two-arm cluster randomized controlled trial in 20 primary schools in New South Wales, Australia (N = 946). Ten schools were allocated to the intervention condition and ten to the wait-list control condition. Children in the intervention condition participated in 12 x 30-minute peer-led fundamental movement skill sessions over a 10-week period. Cardiorespiratory fitness, muscular fitness, motor competence, inhibition, and cognitive flexibility were assessed at baseline and post-intervention. The pre-registered mediation analysis was conducted at the individual level within a structural equation modeling framework, using cluster-robust standard errors to account for non-independence of observations at the classroom level.RESULTSNone of the mediation effects were statistically significant. The intervention significantly improved inhibition (β = 0.125, SE = 0.054, p = 0.021), but not cognitive flexibility (β = 0.013, SE = 0.068, p = 0.845). The intervention improved cardiorespiratory fitness (β = 0.14, SE = 0.051, p = 0.007), but not muscular fitness (β = -0.02, SE = 0.062, p = 0.707) or motor competence (β = 0.04, SE = 0.076, p = 0.568). Muscular fitness was associated with inhibition (β = 0.13, SE = 0.035, p < 0.001), and motor competence was associated with inhibition (β = 0.08, SE = 0.034, p = 0.017) and cognitive flexibility (β = 0.12, SE = 0.030, p < 0.001) at post-intervention.CONCLUSIONSChanges in fitness and motor competence did not mediate the effect of the intervention on children's executive functions. However, the significant associations between mediators and executive functions offer partial support for both the 'fitness' and 'skill acquisition' hypotheses, suggesting their potential importance for children's cognitive development.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145807657","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 test and compare the effects of the four most common exercise-based interventions employed to manage subjective fatigue and functional impairments due to multiple sclerosis (MS).METHODSPersons with MS (PwMS) complaining of fatigue as main symptom were enrolled. After a comprehensive baseline assessment evaluating subjective fatigue impact and severity (primary endpoints), quality of life, cardiorespiratory performance and mobility and motor-functional outcomes, participants were randomly assigned to an eight-week intervention consisting of strength (ST) or aerobic training (AT) or strength+aerobic (Combo) or global rehabilitation (Rehab).RESULTSSixty-two mildly-moderately disabled PwMS (median EDSS 3.5±1.6; age 46.6±11.8 years; 75% women) completed the study. No adverse events were reported. Between-group comparisons did not detect significant differences among groups. Considering training-induced effects separately for each group, AT showed the largest reduction in the Fatigue Severity Score (-18.8%; -0.81 pts, CI: -1.53, -0.09, p=0.03) followed by ST (-16.8%; -0.84 pts, IC: -1.56, -0.12, p=0.02). Fatigue impact assessed by MFIS was significantly reduced after AT (-35.3%; -12.44 pts, CI: -19.00, -5.87, p<0.01), followed by Combo (-33.8%; -13.36 pts; CI: -20.38, -6.34, p<0.01) and Rehab (-26.2%; -8.18 pts; CI: -16.10, -0.26, p=0.04). Regarding motor-functional outcomes, beyond the expected training-specific effects (e.g., muscle strength gains following ST, increased cardiorespiratory fitness following AT), comfortable and fastest walking speed increased significantly following Rehab (+0.16 m·s -1, CI: 0.08, 0.23, p<0.01; +0.22 m·s -1, CI: 0.11, 0.329, p<0.01, respectively) exceeding established thresholds for clinically important changes. Also the increased distance covered in six minutes was found to exceed clinically importance thresholds following ST (+55 m, CI: 9.15, 101.02, p=0.02) and Combo (+62 m, CI: 14.04, 109.13, p=0.01).CONCLUSIONSAlthough the superiority of one treatment over the others has yet to be claimed and all interventions proved beneficial to reduce fatigue impact, only AT and ST reduced both fatigue severity and impact, with the former intervention associated with the largest within-group effect sizes. When testing the effects of interventions on mobility outcomes, AT led to the largest improvements, followed by Combo.
{"title":"Measuring the Effects of the Commonest Exercise Programs on Subjective Fatigue in People with Multiple Sclerosis: A Randomized Effectiveness Trial.","authors":"Anna Boi,Marco Morrone,Gianluca Martinez,Lucia Ventura,Martina Meloni,Davide Natale,Lucia Cugusi,Carmen Oneto,Elia Sechi,Elena Aiello,Franca Deriu,Andrea Manca","doi":"10.1249/mss.0000000000003934","DOIUrl":"https://doi.org/10.1249/mss.0000000000003934","url":null,"abstract":"PURPOSETo test and compare the effects of the four most common exercise-based interventions employed to manage subjective fatigue and functional impairments due to multiple sclerosis (MS).METHODSPersons with MS (PwMS) complaining of fatigue as main symptom were enrolled. After a comprehensive baseline assessment evaluating subjective fatigue impact and severity (primary endpoints), quality of life, cardiorespiratory performance and mobility and motor-functional outcomes, participants were randomly assigned to an eight-week intervention consisting of strength (ST) or aerobic training (AT) or strength+aerobic (Combo) or global rehabilitation (Rehab).RESULTSSixty-two mildly-moderately disabled PwMS (median EDSS 3.5±1.6; age 46.6±11.8 years; 75% women) completed the study. No adverse events were reported. Between-group comparisons did not detect significant differences among groups. Considering training-induced effects separately for each group, AT showed the largest reduction in the Fatigue Severity Score (-18.8%; -0.81 pts, CI: -1.53, -0.09, p=0.03) followed by ST (-16.8%; -0.84 pts, IC: -1.56, -0.12, p=0.02). Fatigue impact assessed by MFIS was significantly reduced after AT (-35.3%; -12.44 pts, CI: -19.00, -5.87, p<0.01), followed by Combo (-33.8%; -13.36 pts; CI: -20.38, -6.34, p<0.01) and Rehab (-26.2%; -8.18 pts; CI: -16.10, -0.26, p=0.04). Regarding motor-functional outcomes, beyond the expected training-specific effects (e.g., muscle strength gains following ST, increased cardiorespiratory fitness following AT), comfortable and fastest walking speed increased significantly following Rehab (+0.16 m·s -1, CI: 0.08, 0.23, p<0.01; +0.22 m·s -1, CI: 0.11, 0.329, p<0.01, respectively) exceeding established thresholds for clinically important changes. Also the increased distance covered in six minutes was found to exceed clinically importance thresholds following ST (+55 m, CI: 9.15, 101.02, p=0.02) and Combo (+62 m, CI: 14.04, 109.13, p=0.01).CONCLUSIONSAlthough the superiority of one treatment over the others has yet to be claimed and all interventions proved beneficial to reduce fatigue impact, only AT and ST reduced both fatigue severity and impact, with the former intervention associated with the largest within-group effect sizes. When testing the effects of interventions on mobility outcomes, AT led to the largest improvements, followed by Combo.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145807542","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 : 2025-12-23DOI: 10.1249/mss.0000000000003929
Matthew I Black,James A Lewis,Yujie Liu,Aitor Altuna,Anni Vanhatalo,Brett S Kirby,Andrew M Jones
PURPOSETo (1) determine whether critical power (CP), W' and W' reconstitution kinetics (W'REC) are altered by high-intensity team-sport specific intermittent exercise; (2) examine the accuracy with which W' balance (W'BAL) is estimated by the W'BAL model; (3) examine whether physiological variables assessed during ramp incremental exercise and the 3-min all-out test, explain exercise-induced changes in the power-duration relationship.METHODSCP, W' and W'REC were determined during a repeated all-out test, which comprised a 3-min all-out test and a 2-min all-out test, separated by 90 s, in 13 recreationally active team-sport players. The test was performed in a rested condition (control) and immediately following a 40-min (40-IST) and 80-min (80-IST) intermittent sprint test.RESULTSCP assessed following the 40-IST (222±57 W) and 80-IST (213±49 W) were not different to control (222±52 W; P>0.05). W'REC was also not significantly different to control (0.08 ± 0.02 kJs -2) following the 40-IST (0.07±0.02 kJs -2) or 80-IST (0.07±0.02 kJs-2; P>0.05). W' was lower than control (13.5±4.0 kJ) following the 40-IST (10.1±4.0 kJ) and 80-IST (9.1±3.5 kJ) (both P<0.05). Following the 40-IST, W'BAL was not significantly different to the value predicted from the W'BAL model (10.9±2.4 kJ; P>0.05), but W'BAL was over-estimated by the model following the 80-IST (10.7±2.6 kJ; P<0.05). There were considerable inter-individual differences in the changes in the power-duration relationship following exercise which were not related to physiological variables assessed in the control condition.CONCLUSIONSCP and W'REC are not altered after intermittent exercise, but W' is decreased, with considerable heterogeneity in the changes in the power-duration relationship between individuals. These results have important implications for the application of the W'BAL model to describe intermittent exercise performance.
{"title":"Dynamics of the Power-Duration Relationship During Intermittent Team Sports Exercise.","authors":"Matthew I Black,James A Lewis,Yujie Liu,Aitor Altuna,Anni Vanhatalo,Brett S Kirby,Andrew M Jones","doi":"10.1249/mss.0000000000003929","DOIUrl":"https://doi.org/10.1249/mss.0000000000003929","url":null,"abstract":"PURPOSETo (1) determine whether critical power (CP), W' and W' reconstitution kinetics (W'REC) are altered by high-intensity team-sport specific intermittent exercise; (2) examine the accuracy with which W' balance (W'BAL) is estimated by the W'BAL model; (3) examine whether physiological variables assessed during ramp incremental exercise and the 3-min all-out test, explain exercise-induced changes in the power-duration relationship.METHODSCP, W' and W'REC were determined during a repeated all-out test, which comprised a 3-min all-out test and a 2-min all-out test, separated by 90 s, in 13 recreationally active team-sport players. The test was performed in a rested condition (control) and immediately following a 40-min (40-IST) and 80-min (80-IST) intermittent sprint test.RESULTSCP assessed following the 40-IST (222±57 W) and 80-IST (213±49 W) were not different to control (222±52 W; P>0.05). W'REC was also not significantly different to control (0.08 ± 0.02 kJs -2) following the 40-IST (0.07±0.02 kJs -2) or 80-IST (0.07±0.02 kJs-2; P>0.05). W' was lower than control (13.5±4.0 kJ) following the 40-IST (10.1±4.0 kJ) and 80-IST (9.1±3.5 kJ) (both P<0.05). Following the 40-IST, W'BAL was not significantly different to the value predicted from the W'BAL model (10.9±2.4 kJ; P>0.05), but W'BAL was over-estimated by the model following the 80-IST (10.7±2.6 kJ; P<0.05). There were considerable inter-individual differences in the changes in the power-duration relationship following exercise which were not related to physiological variables assessed in the control condition.CONCLUSIONSCP and W'REC are not altered after intermittent exercise, but W' is decreased, with considerable heterogeneity in the changes in the power-duration relationship between individuals. These results have important implications for the application of the W'BAL model to describe intermittent exercise performance.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145807544","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 : 2025-12-16DOI: 10.1249/mss.0000000000003916
Hanna Drzymała-Celichowska,Joanna Majerczak,Katarzyna Kryściak,Jan Celichowski,Jerzy A Zoladz
INTRODUCTIONDuring tetanic contractions of fast motor units (MUs), an early increase in force (boost) is followed by a slight decline to a plateau (sag). This boost is present at the onset of activity but disappears during rhythmically repeated contractions at short intervals; however, it may be restituted after a period of rest. Nevertheless, background of the boost, especially the minimum time required to restore this effect is unknown, and the present study aimed to address this gap.METHODSThe functional isolation of a single MU was achieved by splitting the L5 or L4 ventral roots into thin filaments, which were electrically stimulated with rectangular electrical pulses. We recorded series of three 504 ms tetanic contractions (triplets) evoked at 35 Hz repeated once per second, with the boost visible in the first tetanus. The triplets were evoked at progressively shorter time intervals, ranging from 90 to 2 s.RESULTSThe boost in successive triplets reduced when the intervals became critically short. The reduction of boost was estimated by the decrease in sag amplitude following the peak force associated with the boost. In fast fatigue-resistant MUs, the sag amplitude decreased by 25% at an average interval of 29.80 s and by 50% at an interval of 16.84 s. For fast fatigable MUs, the interval required to restitute the studied effect was longer: a 25% reduction in sag corresponded to an interval of 82.29 s, and a 50% reduction corresponded to 54.07 s.CONCLUSIONSThe results suggest that the physiological basis for the restitution of initial force (boost) is the kinetics of muscle energy status recovery following initial exercise.
{"title":"Time Required for the Restitution of Extra Initial Force in Fast Motor Units of the Rat Medial Gastrocnemius Muscle.","authors":"Hanna Drzymała-Celichowska,Joanna Majerczak,Katarzyna Kryściak,Jan Celichowski,Jerzy A Zoladz","doi":"10.1249/mss.0000000000003916","DOIUrl":"https://doi.org/10.1249/mss.0000000000003916","url":null,"abstract":"INTRODUCTIONDuring tetanic contractions of fast motor units (MUs), an early increase in force (boost) is followed by a slight decline to a plateau (sag). This boost is present at the onset of activity but disappears during rhythmically repeated contractions at short intervals; however, it may be restituted after a period of rest. Nevertheless, background of the boost, especially the minimum time required to restore this effect is unknown, and the present study aimed to address this gap.METHODSThe functional isolation of a single MU was achieved by splitting the L5 or L4 ventral roots into thin filaments, which were electrically stimulated with rectangular electrical pulses. We recorded series of three 504 ms tetanic contractions (triplets) evoked at 35 Hz repeated once per second, with the boost visible in the first tetanus. The triplets were evoked at progressively shorter time intervals, ranging from 90 to 2 s.RESULTSThe boost in successive triplets reduced when the intervals became critically short. The reduction of boost was estimated by the decrease in sag amplitude following the peak force associated with the boost. In fast fatigue-resistant MUs, the sag amplitude decreased by 25% at an average interval of 29.80 s and by 50% at an interval of 16.84 s. For fast fatigable MUs, the interval required to restitute the studied effect was longer: a 25% reduction in sag corresponded to an interval of 82.29 s, and a 50% reduction corresponded to 54.07 s.CONCLUSIONSThe results suggest that the physiological basis for the restitution of initial force (boost) is the kinetics of muscle energy status recovery following initial exercise.","PeriodicalId":18500,"journal":{"name":"Medicine & Science in Sports & Exercise","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145759901","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：