Chronic weight control impacts on physiological function and bone health in elite jockeys

Abstract

The aim of this study was to evaluate the impact of weight restrictions on physiological function and bone health in a group of horse racing jockeys. Twenty-seven elite male jockeys participated in this study (17 flat jockeys; 10 national hunt jockeys). Participants completed a range of measurements including anthropometry, hydration analysis, bone mineral density assessment, and musculoskeletal screening. Fifty-nine percent of flat and 40% of national hunt jockeys showed osteopenia in one or more of the total body, hip or spine scans. Mean urine-specific gravity (Usg) values revealed moderate dehydration on a non-race day (Usg = 1.022 ± 0.005 and 1.021 ± 0.007 for flat and national hunt jockeys respectively). Analysis of a number of flat jockeys (n = 11) revealed marked dehydration on an official race day (Usg = 1.028 ± 0.005). Sixty-four percent of participants reported a current injury at the time of assessment. Our results reveal some worrying trends within this population. Further research is required to examine the effects of current weight control practices typically used by jockeys on both physiological and cognitive function as well as health and performance.     

The impact of physical activity and fitness on academic achievement and cognitive performance in children

The potential for physical activity and fitness to improve cognitive function, learning and academic achievement in children has received attention by researchers and policy makers. This paper reports a systematic approach to identification, analysis and review of published studies up to early 2009. A three-step search method was adopted to identify studies that used measures of physical activity or fitness to assess either degree of association with or effect on a) academic achievement and b) cognitive performance. A total of 18 studies including one randomised control trial, six quasi-experimental and 11 correlational studies were included for data extraction. No studies meeting criteria that examined the links between physical activity and cognitive function were found. Weak positive associations were found between both physical activity and fitness and academic achievement and fitness and elements of cognitive function, but this was not supported by intervention studies. There is insufficient evidence to conclude that additional physical education time increases academic achievement; however there is no evidence that it is detrimental. The quality and depth of the evidence base is limited. Further research with rigour beyond correlational studies is essential.     

不同温度脱水速降体重对机体部分生化指标的影响

目的:研究不同温度、时间桑拿浴速降体重对机体部分生化指标的影响.方法:实验对象为健康成年男性8人.受试者采用桑拿浴进行速降体重,实验按照温度条件60℃、70℃、80℃及各温度桑拿时间10 min、15 min进行分组,共分为6组,分别为60℃10min组、60℃15min组、70℃10min组、70℃15 mim组、80℃10 min组、80℃15 min组.桑拿实验采用间歇式桑拿浴法,每次桑拿10 min或15 min,间歇5 min,5次桑拿为一组.每组实验前、后抽取受试者浅表静脉血进行生化指标测试,实验前测试结果作为对照组,实验后测试结果为实验组.结果:60℃15 min组、80℃10 min组两组实验后免疫球蛋白A显著升高(P<0.05);实验前、后红细胞数量、血红蛋白、红细胞压积差别均无显著意义(P>0.05);60℃15min组、80℃15 min组实验后血尿素水平非常显著下降(P<0.01),70℃10 min组、70℃15min组显著下降(P<0.05);6种方法的桑拿浴实验后的血乳酸均非常显著下降(P<0.01);60℃15 min组、70℃15 min组、80℃10 min组、80℃15 min组实验后血清肌酸激酶浓度非常显著升高(P<0.01),70℃10 min 组显著升高(P<0.05); 70℃15 min 组实验后血睾酮水平非常显著升高(P<0.01),80℃10 min组显著升高(P<0.05).结论:受试者的免疫系统、氧转运系统、内分泌系统未受到不利影响;桑拿浴可以显著减少血液中能量物质的代谢产物;桑拿浴将导致血清肌酸激酶的升高,6种桑拿浴方法中60℃10 min组与70℃10 min组对骨骼肌系统的影响较小.     

快速减重对人体血液流变学特性的影响

目的:通过观察快速减重前后的血液流变学各项指标的变化,探讨快速减重对血液流变学特性的影响。方法:测定受试者正常水合(0%BWL)、桑拿或运动脱水快速减重2%(2%BWL)、4%(4%BWL)3种不同状态下的血液流变性的指标,观察全血粘度(高、中、低切)、血浆粘度(PV)、红细胞压积(Hct%)、红细胞变形指数(TK)、红细胞刚性指数(VR)、红细胞聚集指数(A1、A2)等指标的动态数值。结果:(1)2%BWL和4%BWL时全血粘度(高、中、低切)、血浆粘度、红细胞压积、纤维蛋白原(Fi)、TK、VR、A1、A2明显升高(P﹤0.05);(2)4%BWL时血液流变学各指标变化明显高于2%BWL(P﹤0.05);(3)桑拿快速脱水组与运动快速脱水组的血液流变学各指标在同等程度脱水程度下相比较,有差异,但差异没有统计学意义(P>0.05)。结论:快速减重可引起血液流变性的显著性变化;快速减重的程度与血液流变性的改变密切相关;快速减重对血液循环和微循环的影响,关键在于快速减重的程度,与脱水方式关系不明显。     

Characteristics of extracurricular physical activity and cognitive performance in adolescents. The AVENA study

Abstract

The aim of this report was to examine the associations between some characteristics (i.e., structure and number) of extracurricular physical activity (EPA) and cognitive performance in adolescents. A total of 1662 adolescents (880 girls; 13.0–18.5 years) from 5 Spanish cities (Granada, Madrid, Murcia, Santander and Zaragoza) were included in this study. Structure (organised and non-organised) and number of EPAs, and participation at vigorous intensity during EPA were self-reported. Cognitive performance (verbal, numeric and reasoning abilities, and an overall score) was measured with the “SRA-Test of Educational Ability”. Results showed that vigorous EPA was positively associated with all cognitive variables. Adolescents who practiced an organised EPA had higher scores in 3 of the 4 cognitive variables than those who practiced a non-organised EPA (all P < 0.05). Likewise, the group who participated in more than one EPA had higher cognitive performance in all variables than the group who participated in only one EPA (all P < 0.05). Regardless of potential confounder variables, including vigorous EPA, both structure and number of EPAs were each other independently associated with cognitive performance. Therefore, structure and number of EPAs may positively influence cognitive performance in adolescents. Participating in multiple, organised EPA may have benefits for cognitive performance.     

不同快速降体重量对肌肉功能的影响

目的:探讨不同快速降体重量对肌肉功能的影响;方法:以12名健康男生为实验对象,测定脱水前(0%bw l)、桑拿脱水快速降体重2%(2%bw l)、桑拿脱水快速降体重4%(4%bw l)这3种不同体重状态下最大等速肌力、等速肌耐力与无氧作功能力;在测定无氧作功能力时,结合运用主观用力程度等级评价量表(RPE),对肌肉功能进行系统评价;结果:1)2%bw l和4%bw l对肌肉的最大等速力量均没有削弱作用;2%bw l后,屈肘肌群的最大等速肌力反而增大。2)2%bw l对屈、伸肘肌群以及屈、伸膝肌群的等速肌耐力均没有影响;4%bw l后,屈肘肌群与屈、伸膝肌群的等速肌耐力不变,而伸肘肌群的等速肌耐力显著性下降。3)2%bw l和4%bw l对下肢的无氧耐力没有削弱作用。     

The time-frame of acute resistance exercise effects on football skill performance: The impact of exercise intensity

Abstract

The purpose of this study was to determine the recovery rate of football skill performance following resistance exercise of moderate or high intensity. Ten elite football players participated in three different trials: control, low-intensity resistance exercise (4 sets, 8–10 repetitions/set, 65–70% 1 repetition maximum [1RM]) and high-intensity resistance exercise (4 sets, 4–6 repetitions/set, 85–90% 1RM) in a counterbalanced manner. In each experimental condition, participants were evaluated pre, post, and at 24, 48, 72 h post exercise time points. Football skill performance was assessed through the Loughborough Soccer Passing Test, long passing, dribbling, shooting and heading. Delayed onset muscle soreness, knee joint range of motion, and muscle strength (1RM) in squat were considered as muscle damage markers. Blood samples analysed for creatine kinase activity, C-reactive protein, and leukocyte count. Passing and shooting performance declined (P < 0.05) post-exercise following resistance exercise. Strength declined post-exercise following high-intensity resistance exercise. Both trials induced only a mild muscle damage and inflammatory response in an intensity-dependent manner. These results indicate that football skill performance is minimally affected by acute resistance exercise independent of intensity suggesting that elite players may be able to participate in a football practice or match after only 24 h following a strength training session.     

Effects of acute exercise,dehydration and rehydration on cognitive function in well-trained athletes

This study investigated the effects of aerobic exercise, fluid loss and rehydration on cognitive performance in well-trained athletes. Ten endurance-trained males (25 ± 5 years; 175 ± 5 cm; 70.35 ± 5.46 kg; VO_2max, 62.95 ± 7.20 ml · kg.min^?1) lost ~2.5 ± 0.6% body mass via continuous cycling exercise at ~65% peak sustainable power output (60 min duration) before consuming different beverages (Water = W1 and W2, Sustagen Sport = SS, Powerade = PD) and food ad libitum on four separate occasions. Cognitive function using a four-choice reaction time task (CRT), body mass, fluid consumption volumes, urine samples and subjective ratings (alertness, concentration, energy) were obtained before and after exercise, and hourly during recovery (for 4 h). CRT latency was significantly reduced immediately after exercise compared to pre-exercise measures for all trials (W1 = ?16 ± 18 ms, W2 = ?22 ± 21 ms, PD = ?22 ± 22 ms, SS = ?19 ± 26 ms). However, this effect was short-lived with subsequent measures not different from pre-exercise values. No difference in CRT accuracy was observed at any time across all trials. Subjective ratings were not different at any time across all trials. Aerobic exercise, hypohydration or an interaction between these two may provide a small cognitive performance benefit. However, these effects are temporary and confined to the immediate post-exercise period.     

The relative impact of cognitive anxiety and self-confidence upon sport performance: a meta-analysis

This meta-analysis (k = 48) investigated two relationships in competitive sport: (1) state cognitive anxiety with performance and (2) state self-confidence with performance. The cognitive anxiety mean effect size was r = -0.10 (P < 0.05). The self-confidence mean effect size was r = 0.24 (P < 0.001). A paired-samples t-test revealed that the magnitude of the self-confidence mean effect size was significantly greater than that of the cognitive anxiety mean effect size. The moderator variables for the cognitive anxiety-performance relationship were sex and standard of competition. The mean effect size for men (r = -0.22) was significantly greater than the mean effect size for women (r = -0.03). The mean effect size for high-standard competition (r = -0.27) was significantly greater than that for comparatively low-standard competition (r = -0.06). The significant moderator variables for the self-confidence-performance relationship were sex, standard of competition and measurement. The mean effect size for men (r = 0.29) was significantly greater than that for women (r = 0.04) and the mean effect size for high-standard competition (r = 0.33) was significantly greater than that for low-standard competition (r = 0.16). The mean effect size derived from studies employing the Competitive State Anxiety Inventory-2 (r = 0.19) was significantly smaller than the mean effect size derived from studies using other measures of self-confidence (r = 0.38). Measurement issues are discussed and future research directions are offered in light of the results.     

The role of a short post-lunch nap in improving cognitive,motor, and sprint performance in participants with partial sleep deprivation

Abstract

The aim of this study was to determine the effects of a post-lunch nap on subjective alertness and performance following partial sleep loss. Ten healthy males (mean age 23.3 years, s = 3.4) either napped or sat quietly from 13:00 to 13:30 h after a night of shortened sleep (sleep 23:00 – 03:00 h only). Thirty minutes after the afternoon nap or control (no-nap) condition, alertness, short-term memory, intra-aural temperature, heart rate, choice reaction time, grip strength, and times for 2-m and 20-m sprints were recorded. The afternoon nap lowered heart rate and intra-aural temperature. Alertness, sleepiness, short-term memory, and accuracy at the 8-choice reaction time test were improved by napping (P < 0.05), but mean reaction times and grip strength were not affected (P > 0.05). Sprint times were improved. Mean time for the 2-m sprints fell from 1.060 s (s _[xbar]  = 0.018) to 1.019 s (s _[xbar]  = 0.019) (P = 0.031 paired t-test); mean time for the 20-m sprints fell from 3.971 s (s _[xbar]  = 0.054) to 3.878 s (s _[xbar]  = 0.047) (P = 0.013). These results indicate that a post-lunch nap improves alertness and aspects of mental and physical performance following partial sleep loss, and have implications for athletes with restricted sleep during training or before competition.     

我国肥胖病人运动处方的特点及制定方法

伴随着国民经济的发展与提高,我国肥胖病的发病率正急速上升,越来越多的人谈“肥”色变。章针对肥胖病的特点,提出了有效的减肥运动处方。     

运动员高级认知过程研究的方法范式探析

运动员的高级认知过程，如运动思维、运动决策等，一直是体育运动心理学研究的重要内容之一。在这一研究领域，专家一新手研究设计和眼动记录法、电影定格方法和口语报告法等研究方法一起，构成了当前研究运动员高级认知过程的方法范式。从认知心理学角度来看，眼动记录法和电影定格方法属基于模式识别的范式，口语报告法属基于知识的范式。在研究运动员的高级认知过程中，将这两类研究方法结合起来开展研究，将是今后在研究方法的遴选中可以采纳的一种抉择。     

足球训练与认知风格对分配性注意的影响

为探究足球训练与认知风格对分配性注意的影响,随机选取足球专项大学生和普通文化课大学生各100名进行《认知方式图形镶嵌测验》,筛选出60名场独立型被试和38名场依存型被试,通过视听双通道实验测量分配性注意水平。结果显示,场独立型大学生中,足球专项大学生的分配性注意水平显著高于普通大学生,场依存型大学生中,足球专项大学生和普通大学生的分配性注意水平不存在显著差异;场独立型大学生的分配性注意水平显著高于场依存型大学生。这表明,足球训练和认知风格对分配性注意水平都有显著影响,可以通过足球训练提高场独立型个体的分配性注意水平。     

The impact of limb deficiency impairment on Para swimming performance

ABSTRACT

Swimmers with limb deficiency are a core population within Para Swimming, accordingly this study examined the contribution of limb segments to race performance in these swimmers. Data were obtained for 174 male Para swimmers with limb deficiency. Ensemble partial least squares regression showed accurate predictions when using relative limb segment lengths to estimate Para swimmers’ personal best race performances. The contribution of limb segments to performance in swim events was estimated using these regression models. The analysis found swim stroke and event distance to influence the contributions of limb segments to performance. For freestyle swim events, these changes were primarily due to the increased importance of the hand, and decreased importance of the foot and shank, as the distance of the event increased. When comparing swim strokes, higher importance of the thigh and shank in the 100 m breaststroke compared with other swim strokes confirms the separate SB class. Varied contributions of the hand, upper arm and foot suggest that freestyle could also be separated from backstroke and butterfly events to promote fairer classification. This study shows that swim stroke and event distance influence the activity limitation of Para swimmers with limb deficiency suggesting classification should account for these factors.     

Effect of acute L-Alanyl-L-Glutamine and electrolyte ingestion on cognitive function and reaction time following endurance exercise

The purpose of this study was to examine the effect of the L-Alanyl-L-Glutamine dipeptide (AG) on cognitive function and reaction time (RT) following endurance exercise. Twelve male endurance athletes (23.5 ± 3.7 y; 175.5 ± 5.4 cm; 70.7 ± 7.6 kg) performed four trials, each consisting of running on a treadmill at 70% of VO₂max for 1h, then at 90% of VO₂max until exhaustion. One trial consisted of no hydration (DHY), another required ingestion of only a sports electrolyte drink (ED) and two trials required ingestion of a low dose (LD; 300 mg·500 ml^?1) and high dose (HD) of AG (1 g·500ml^?1) added to the ED. Cognitive function and reaction tests were administered pre- and post-exercise. Magnitude based inferences were used to analyze ? cognitive function and ? reaction test data. Results indicated that DHY had a possible negative effect on number of hits in a 60-sec reaction test compared to LD and HD, while ED appeared to have a negative effect compared to HD. Analysis of lower body quickness indicated that LD and HD were likely improved in comparison to DHY. Performance on the serial subtraction test appeared to be possibly better in ED than DHY, while other comparisons between groups regarding cognitive function were unclear. In conclusion, rehydrating with AG during submaximal exercise may maintain or enhance subsequent RT in upper and lower body activities compared to DHY. These same effects were not apparent when participants consumed ED.     

The role of self-regulatory efficacy,moral disengagement and guilt on doping likelihood: A social cognitive theory perspective

Given the concern over doping in sport, researchers have begun to explore the role played by self-regulatory processes in the decision whether to use banned performance-enhancing substances. Grounded on Bandura’s (1991) theory of moral thought and action, this study examined the role of self-regulatory efficacy, moral disengagement and anticipated guilt on the likelihood to use a banned substance among college athletes. Doping self-regulatory efficacy was associated with doping likelihood both directly (b = ?.16, P < .001) and indirectly (b = ?.29, P < .001) through doping moral disengagement. Moral disengagement also contributed directly to higher doping likelihood and lower anticipated guilt about doping, which was associated with higher doping likelihood. Overall, the present findings provide evidence to support a model of doping based on Bandura’s social cognitive theory of moral thought and action, in which self-regulatory efficacy influences the likelihood to use banned performance-enhancing substances both directly and indirectly via moral disengagement.     

对沈阳市健身俱乐部大众健美操参与者认知特征的研究

采用文献资料法、问卷调查法和逻辑分析法,对沈阳市三家健身俱乐部大众健美操参与者的认知行为特征进行研究。     

The effects of anxiety upon psychomotor performance

This paper describes an experiment which examined the effects of anxiety on choice reaction time and movement time. A balanced repeated measures design was adopted in which eight female subjects performed a six‐choice visual reaction task in ‘no anxiety’ and ‘anxiety’ conditions. The anxiety condition required subjects to jump from a balcony 15 feet (4.57 m) into a foam‐filled pit below. Subjects in the anxiety condition demonstrated significantly higher levels of cognitive anxiety and longer reaction times than those in the no anxiety condition. The analysis of the reaction time data also revealed a significant interaction between anxiety and block. No significant effects emerged in the case of movement time.     

认知结构理论与体育教学

通过文献资料的研究，结合体育教学的特点和规律，揭示了认知结构理论与体育教学的内在联系，提出了运用认知结构和认知策略改革体育教学活动的新观点和新作法，为有效地组织和完成体育教学任务提供了心理学依据。     

赛艇运动员减体重期的代谢及膳食措施

赛艇运动是一项奖牌多、按体重级别进行比赛的竞技体育运动。科学地控制体重或减体重是一个十分重要而现实的问题,教练员和运动员要有一个科学的认识。本文从赛艇运动员营养特点、减体重的方法及医学问题和减体重期间的膳食措施进行分析研究。