Journal of Sports Sciences最新文献_第10页

Passive dehydration reduces muscle thickness after resistance exercise. 被动脱水会减少阻力运动后的肌肉厚度。

IF 2.3 2区医学

Journal of Sports Sciences Pub Date : 2025-02-01 Epub Date: 2025-01-27 DOI: 10.1080/02640414.2025.2456402

Casey R Appell, Nigel C Jiwan, Yasuki Sekiguchi, Hui-Ying Luk

{"title":"Passive dehydration reduces muscle thickness after resistance exercise.","authors":"Casey R Appell, Nigel C Jiwan, Yasuki Sekiguchi, Hui-Ying Luk","doi":"10.1080/02640414.2025.2456402","DOIUrl":"10.1080/02640414.2025.2456402","url":null,"abstract":"Dehydration-induced increased plasma osmolality (Posmo) alters whole body fluid balance which could alter resistance exercise (RE) induced intramuscular (IM) fluid shift.Purpose: The purpose of the current report was to investigate the effect of dehydration on RE-induced change in whole body fluid balance in resistance trained (RT) men.Methods: Fourteen RT men performed two identical RE sessions, either in a hydrated (EUHY) or dehydrated (DEHY) state induced by a 24 hr fluid restriction. Total body fluid, urine osmolality (Uosmo), urine specific gravity (USG), Posmo, hematocrit (HCT), muscle thickness were measured and plasma volume (%ΔPV) was calculated using HCT.Results: A significant (p < 0.050) condition effect was observed for total body fluid and muscle thickness such that EUHY was 2.6% and 13.0% greater than DEHY, respectively. Significant time × condition effects were observed for Posmo, Uosmo, and USG. At all times, EUHY (collapsing for time: Posmo: 3.9%; Uosmo: 133.5%; USG: 1.6%) was lower than DEHY. A significant time effect was observed for %ΔPV. %ΔPV 5 min after RE was -12.5% lower than PRE.Conclusion: Dehydration with RE altered whole body fluid balance indicated by greater fluid retention and efflux of IM fluid could at least partly maintain %ΔPV following DEHY in RT men.","PeriodicalId":17066,"journal":{"name":"Journal of Sports Sciences","volume":" ","pages":"336-347"},"PeriodicalIF":2.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143046330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Tissue oxygenation in response to low-load and high-load back squats with continuous blood flow restriction in athletes. 组织氧合对运动员低负荷和高负荷后深蹲持续血流限制的反应。

IF 2.3 2区医学

Journal of Sports Sciences Pub Date : 2025-01-30 DOI: 10.1080/02640414.2025.2457859

Charles W C Simpson, Katelyn S Moore, Hoani K Smith, Betul Coskun, Michael J Hamlin

{"title":"Tissue oxygenation in response to low-load and high-load back squats with continuous blood flow restriction in athletes.","authors":"Charles W C Simpson, Katelyn S Moore, Hoani K Smith, Betul Coskun, Michael J Hamlin","doi":"10.1080/02640414.2025.2457859","DOIUrl":"https://doi.org/10.1080/02640414.2025.2457859","url":null,"abstract":"To determine muscle oxygenation with continuous blood flow restriction (BFR) training in high load (HL), 80% one-repetition maximum (1RM) and low load (LL), 30% 1RM squat exercises. In week-2 of a 4-week resistance training programme as part of their 3-set training routine, two groups of athletes (n = 4 each), one performing HL training with low cuff pressure (20% arterial occlusion pressure (AOP)), the other LL training with high cuff pressure (60% AOP) had muscle oxygenation assessed with near-infrared spectrophotometry (NIRS), arterial oxygen saturation (SPO2), heart rate (HR), barbell velocity and ratings of perceived exertion (RPE) during barbell back squats (BBS). Changes in the vastus lateralis oximetry were compared to pre- and post-training squat (1RM). Across athletes, there were significant associations between two pre-set-3 exercise variables and post-training 1RM, Tissue Saturation Index (TSI) (R2 = 0.92, p < 0.0002) and HHb concentration (R2 = 0.79, p < 0.003). Generalised regression models indicated that TSI % and HHb concentrations before and after set 3 timepoints were significant predictors of post-training 1RM in the LL group (R2 = 0.99, BIC = -24.9). Well-tolerated continuous LL-BFR training provided greater increases in strength than HL-BFR in athletes.","PeriodicalId":17066,"journal":{"name":"Journal of Sports Sciences","volume":" ","pages":"1-10"},"PeriodicalIF":2.3,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143066260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effects of blood flow restriction on internal and external training load metrics during acute and chronic short-term repeated-sprint training in team-sport athletes. 在团队运动运动员急性和慢性短期重复短跑训练中，血流限制对内外训练负荷指标的影响。

IF 2.3 2区医学

Journal of Sports Sciences Pub Date : 2025-01-30 DOI: 10.1080/02640414.2025.2457863

James R Mckee, Kristen De Marco, Olivier Girard, Jeremiah J Peiffer, Brendan R Scott

{"title":"Effects of blood flow restriction on internal and external training load metrics during acute and chronic short-term repeated-sprint training in team-sport athletes.","authors":"James R Mckee, Kristen De Marco, Olivier Girard, Jeremiah J Peiffer, Brendan R Scott","doi":"10.1080/02640414.2025.2457863","DOIUrl":"https://doi.org/10.1080/02640414.2025.2457863","url":null,"abstract":"This study examined internal, external training loads, internal:external ratios, and aerobic adaptations for acute and short-term chronic repeated-sprint training (RST) with blood flow restriction (BFR). Using randomised crossover (Experiment A) and between-subject (Experiment B) designs, 15 and 24 semi-professional Australian footballers completed two and nine RST sessions, respectively. Sessions comprised three sets of 5-7 × 5-second sprints and 25 seconds recovery, with continuous BFR (45% arterial occlusion pressure) or without (Non-BFR). Banister's, Edwards', Lucia's training impulse, and session rating of perceived exertion training load (sRPETL) were calculated. External training loads were determined by total work done (TWD). Ventilatory threshold power outputs were assessed during a graded exercise test post-RST. Internal training loads were comparable between conditions, though BFR reduced (p < 0.02) TWD during acute (-4.9%) and short-term chronic (-10.0%) RST compared to Non-BFR. Furthermore, BFR increased (p = 0.049) the sRPETL:TWD ratio during short-term chronic (+14.8%), but not acute RST. First and second ventilatory threshold power outputs improved (+8.3% and + 4.2%, respectively) similarly for both groups following RST. Repeated exposure to progressively overloaded RST with BFR increases internal demands for a given workload, which may promote beneficial physiological adaptations compared to Non-BFR, though aerobic performance was not further enhanced.","PeriodicalId":17066,"journal":{"name":"Journal of Sports Sciences","volume":" ","pages":"1-10"},"PeriodicalIF":2.3,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143066181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effectiveness of blood flow restriction training during a taper phase in basketball players. 篮球运动员减量阶段血流量限制训练的有效性。

IF 2.3 2区医学

Journal of Sports Sciences Pub Date : 2025-01-25 DOI: 10.1080/02640414.2025.2454712

Hoani K Smith, Stephen P Bird, Betul Coskun, Peter D Olsen, Thomas Kavanagh, Michael J Hamlin

{"title":"Effectiveness of blood flow restriction training during a taper phase in basketball players.","authors":"Hoani K Smith, Stephen P Bird, Betul Coskun, Peter D Olsen, Thomas Kavanagh, Michael J Hamlin","doi":"10.1080/02640414.2025.2454712","DOIUrl":"https://doi.org/10.1080/02640414.2025.2454712","url":null,"abstract":"This study investigates the effectiveness of blood flow restriction (BFR) training in maintaining athletic performance during a taper phase in basketball players. The taper phase aims to reduce external load while maintaining training intensity. Seventeen experienced basketball players were randomised into two groups: a placebo group (n = 8, 22.0 ± 2.1 years, mean ± SD) and BFR group (n = 9, 21.1 ± 1.5 years). The training schedule included strength trainings, team trainings, individual skill sessions and competitive games. During the 4-week taper period, lifting volume was reduced while either maintaining (placebo) or reducing (BFR) lifting load. The BFR group lifted with 60% arterial occlusion pressure at 25-30% of their 1RM, whereas the placebo group trained at 80% of their 1RM with BFR cuffs inflated to only 20%. Compared to the placebo group, BFR participants improved 5 m (-1.4 ± 1.5% mean ± 95% CI p = 0.03) and 10 m (-1.1 ± 0.5%, p = <0.01) sprint performance along with barbell back squat (9.6 ± 8.0%, p = 0.013) and countermovement jump (1.1 ± 0.8%, p = 0.0035). BFR during the taper phase enabled a reduction in lifting load with no reduction in subsequent performance measures.","PeriodicalId":17066,"journal":{"name":"Journal of Sports Sciences","volume":" ","pages":"1-12"},"PeriodicalIF":2.3,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143039453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A reflection on systems thinking as a research tool in sport and exercise science. 将系统思维作为体育运动科学研究工具的思考。

IF 2.3 2区医学

Journal of Sports Sciences Pub Date : 2025-01-01 Epub Date: 2024-10-07 DOI: 10.1080/02640414.2024.2391184

Barry Drust

引用次数: 0

Applying a systems thinking lens to anti-doping: A systematic review identifying the contributory factors to doping in sport. 从系统思维的角度看待反兴奋剂问题：系统审查：确定体育运动中使用兴奋剂的促成因素。

IF 2.3 2区医学

Journal of Sports Sciences Pub Date : 2025-01-01 Epub Date: 2024-01-29 DOI: 10.1080/02640414.2024.2306056

Mitchell Naughton, Paul M Salmon, Hugo A Kerhervé, Scott McLean

{"title":"Applying a systems thinking lens to anti-doping: A systematic review identifying the contributory factors to doping in sport.","authors":"Mitchell Naughton, Paul M Salmon, Hugo A Kerhervé, Scott McLean","doi":"10.1080/02640414.2024.2306056","DOIUrl":"10.1080/02640414.2024.2306056","url":null,"abstract":"The use of performance enhancing substances and methods (known as \"doping\") in sport is an intractable issue, with current anti-doping strategies predominantly focused on the personal responsibility and strict liability of individual athletes. This is despite an emerging understanding that athletes exist as part of a broader complex sports system that includes governance, policymakers, media, sponsors, clubs, team members, and athlete support staff, to name a few. As such, there is a need to examine the broader systemic factors that influence doping in sport. The aim of this systematic review was to identify and synthesise the factors contributing to doping and doping behaviours, attitudes, and beliefs and the extent to which this knowledge extends beyond the athlete to consider broader sports systems. The review followed PRISMA guidelines with risk of bias and study quality assessed by the Mixed Methods Appraisal Tool, and identified contributory factors synthesised and mapped onto a systems thinking-based framework. Overall, the included studies were determined to be of high quality. Support personnel, the coach, and the coach-athlete relationship represent key influences on the athletes' decisions to dope. From the evidence presented, doping is an emergent property of sport systems and represents a complex systemic problem that will require whole-of-system interventions. The implications for this and the focus of future research are discussed.","PeriodicalId":17066,"journal":{"name":"Journal of Sports Sciences","volume":" ","pages":"8-22"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139570668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Active primitive reflexes obstruct tactical and technical skills in football players. 活跃的原始反射阻碍了足球运动员的战术和技术技能。

IF 2.3 2区医学

Journal of Sports Sciences Pub Date : 2025-01-01 Epub Date: 2024-12-01 DOI: 10.1080/02640414.2024.2434800

Julie Bastiere, Thibault Lussiana, Aurélien Patoz, Cyrille Gindre, Laurent Mourot

{"title":"Active primitive reflexes obstruct tactical and technical skills in football players.","authors":"Julie Bastiere, Thibault Lussiana, Aurélien Patoz, Cyrille Gindre, Laurent Mourot","doi":"10.1080/02640414.2024.2434800","DOIUrl":"10.1080/02640414.2024.2434800","url":null,"abstract":"Primitive reflexes (PRs) are involuntary motor responses present at birth, typically replaced by voluntary motor control during development. If PRs remain active beyond infancy, they can impair motor and cognitive abilities. This study investigated the correlation between active PRs and Tactical (TaS) and Technical Skills (TeS) in professional football matches. Fifty-eight male football players (17.5 ± 1.4 years) from a French academy were assessed for PR activity, categorized into inactive or active PR groups. Assessed PRs included asymmetrical tonic neck reflex (ATNR), symmetrical tonic neck reflex (STNR), tonic labyrinthine reflex (TLR), and Moro reflex (MR). Analysis of twenty matches showed players with active PRs had significantly lower success rates in TaS and TeS, including 15.5% and 31.8% lower pass success in imbalance and finishing zones (p < 0.01). Players with active PRs also performed worse in defensive actions and duels (p < 0.01). The findings highlight that active PRs hinder football performance, especially in challenging match situations like duels and crowded zones. This suggests the need for training programs to address PR effects and enhance player performance. Further research should refine methods for integrating these RPs.","PeriodicalId":17066,"journal":{"name":"Journal of Sports Sciences","volume":" ","pages":"162-172"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142770000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Associations between objective measures of performance-related characteristics and perceived stress in young cross-country skiers during pre-season training. 年轻越野滑雪运动员在季前训练中与成绩相关的客观特征与感知压力之间的关系。

IF 2.3 2区医学

Journal of Sports Sciences Pub Date : 2025-01-01 Epub Date: 2024-01-21 DOI: 10.1080/02640414.2024.2304499

Christina Mishica, Heikki Kyröläinen, Sara Taskinen, Esa Hynynen, Ari Nummela, Hans-Christer Holmberg, Vesa Linnamo

{"title":"Associations between objective measures of performance-related characteristics and perceived stress in young cross-country skiers during pre-season training.","authors":"Christina Mishica, Heikki Kyröläinen, Sara Taskinen, Esa Hynynen, Ari Nummela, Hans-Christer Holmberg, Vesa Linnamo","doi":"10.1080/02640414.2024.2304499","DOIUrl":"10.1080/02640414.2024.2304499","url":null,"abstract":"Monitoring performance-related characteristics of athletes can reveal changes that facilitate training adaptations. Here, we examine the relationships between submaximal running, maximal jump performance (CMJ), concentrations of blood lactate, sleep duration (SD) and latency (SL), and perceived stress (PSS) in junior cross-country skiers during pre-season training. These parameters were monitored in 15 male and 14 females (17 ± 1 years) for the 12-weeks prior to the competition season, and the data was analysed using linear and mixed-effect models. An increase in SD exerted a decrease in both PSS (B = -2.79, p ≤ 0.01) and blood lactate concentrations during submaximal running (B = -0.623, p ≤ 0.05). In addition, there was a negative relationship between SL and CMJ (B = -0.09, p = 0.08). Compared to males, females exhibited higher PSS scores and little or no change in performance-related tests. A significant interaction between time and sex was present in CMJ with males displaying an effect of time on CMJ performance. For all athletes, lower PSS appeared to be associated with longer overnight sleep. Since the females experienced higher levels of stress, monitoring of their PSS might be beneficial. These findings have implications for the preparation of young athletes' competition season.","PeriodicalId":17066,"journal":{"name":"Journal of Sports Sciences","volume":" ","pages":"135-144"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139512842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Analysis of the motor behaviour of people without specific dance training in improvisation tasks: Influence of mirror and partner. 分析未受过专门舞蹈训练的人在即兴表演任务中的运动行为：镜子和舞伴的影响

IF 2.3 2区医学

Journal of Sports Sciences Pub Date : 2025-01-01 Epub Date: 2024-01-24 DOI: 10.1080/02640414.2024.2306064

Elena Pérez-Calzado, Javier Coterón, Ángel Ric, Carlota Torrents

{"title":"Analysis of the motor behaviour of people without specific dance training in improvisation tasks: Influence of mirror and partner.","authors":"Elena Pérez-Calzado, Javier Coterón, Ángel Ric, Carlota Torrents","doi":"10.1080/02640414.2024.2306064","DOIUrl":"10.1080/02640414.2024.2306064","url":null,"abstract":"This study aims to analyse the influence of the mirror and/or partner constraints on the motor creativity of women without specific training in dance during improvisation tasks, in order to contribute to the knowledge of creativity in the field of sports science and movement-based practices. We studied the exploratory behaviour and emerging movement patterns of 12 women who performed four improvisations under the following situations: individual without mirror; individual with mirror; partner without mirror; and partner with mirror. The dynamic overlap qd(t) was calculated to identify the exploratory dynamics composed of the exploratory amplitude and the rate of change between movement configurations. To determine emerging movement patterns, a principal component analysis was carried out by ad hoc routines prepared. A mixed linear model was performed to find out the influence of the different constraints on the exploratory behaviour. The results indicate that the presence of the mirror seems to provoke a decrease in the exploratory behaviour. In addition, partner improvisation favoured coupling and imitation dynamics among the participants. Likewise, the most recurrent emergent movement pattern was walking while moving the arms. It would be advisable to take the influence of these constraints into consideration depending on the improvisation purpose and the experience level of female participants.","PeriodicalId":17066,"journal":{"name":"Journal of Sports Sciences","volume":" ","pages":"60-70"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139545536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Are we assessing motor competence? Evidence-informed constructs for motor competence in preschoolers through an Exploratory Graph Analysis. 我们在评估运动能力吗？通过探索性图表分析，对学龄前儿童运动能力的构建进行实证分析。

IF 2.3 2区医学

Journal of Sports Sciences Pub Date : 2025-01-01 Epub Date: 2024-10-15 DOI: 10.1080/02640414.2024.2414361

Paulo Felipe Ribeiro Bandeira, Luís Filipe Lemos, Isaac Estevan, Elisabeth Kipling Webster, Cain Truman Clark, Michael Joseph Duncan, Jorge Augusto Mota, Clarice Lucena Martins

{"title":"Are we assessing motor competence? Evidence-informed constructs for motor competence in preschoolers through an Exploratory Graph Analysis.","authors":"Paulo Felipe Ribeiro Bandeira, Luís Filipe Lemos, Isaac Estevan, Elisabeth Kipling Webster, Cain Truman Clark, Michael Joseph Duncan, Jorge Augusto Mota, Clarice Lucena Martins","doi":"10.1080/02640414.2024.2414361","DOIUrl":"10.1080/02640414.2024.2414361","url":null,"abstract":"Motor competence (MC) is conceptually defined as a multidimensional latent construct that covers the proficient performance in motor skills and its underlying mechanisms This study aimed to statistically provide arguments that MC is a network of interconnected constructs, such as FMS, coordination, and its underlying mechanisms, which are responsible for preschoolers' proficiency in motor tasks. Participated 102 preschoolers (65 girls, M age = 4.22 ± 0.19) who were assessed for the Test of Gross Motor Development - 2nd edition, the Motor Competence Assessment, and the Supine-to-Stand. Data were explored using Exploratory Graph Analysis, using the EGAnet package in RStudio. A four-dimensional structure (61.2% of interactions) comprising tasks of the different protocols was underlined, in which all the nodes presented stable and adequate indexes (≥0.65; TEFI = -2.67). Four dimensions of MC were highlighted, namely Dimension 1, which combined movements for locomotor patterns; Dimension 2, comprising three process-oriented measures of object control skills to project objects; Dimension 3, which comprised of skills which require body coordination to displace body through space; and Dimension 4, composed by object control skills evaluated through product-oriented measures. For a better understanding of MC, the assessment of these different aspects that comprises MC should be considered.","PeriodicalId":17066,"journal":{"name":"Journal of Sports Sciences","volume":" ","pages":"109-116"},"PeriodicalIF":2.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142468471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0