Effect of a Brazilian Jiu-jitsu-simulated tournament on strength parameters and perceptual responses

This study aimed to analyse the effects of a simulated Brazilian jiu-jitsu (BJJ) tournament on vertical jump performance, grip strength test and perceived effort responses. 22 male BJJ athletes participated in a simulated tournament consisting of three 7 min matches separated by 14 min of rest. Kimono grip strength test (KGST), counter movement jump (CMJ) and rate of perceived exertion (RPE) were measured before and after each match, while RPE of specific areas was assessed after three matches. ANOVA for repeated measures was used to compare strength parameters after each match with the level of significance set at 5%. The key results showed a significant decrease of jump height (p = 0.001) and net vertical impulse in the CMJ (p = 0.031), as well as a reduction of the number of reps in the KGST (p < 0.001). A significant increase of RPE was found throughout the matches (p < 0.001). Considering the RPE in specific areas, no differences were observed between the upper and lower body (p = 0.743). We conclude that the BJJ simulated tournament generated a decrease of performance in both upper and lower limbs and provoked a progressive increase in the effort perception over the matches.     

Maximal heart rate declines linearly with age independent of cardiorespiratory fitness levels

There have been many conflicting observations between the linear or curvilinear decline in maximal heart rate (HR_max) with age. The aim of this study was to determine if linear or curvilinear equations would better describe the decline in HR_max with age in individuals of differing cardiorespiratory fitness (CRF) levels. Treadmill cardiopulmonary exercise test (CPX) results from participants (1510 men and 1134 women; 18–76 years) free of overt cardiovascular disease were retrospectively examined using cross-sectional and longitudinal study designs. Participants completing ≥2 CPX with ≥1 year between test dates were included in the longitudinal analysis (325 men and 150 women). Linear and quadratic regressions were applied to age and HR_max for the whole cohort and respective CRF groups (high, moderate, and low, relative to age and gender normative values). To test for differences among linear, quadratic, and polynomial equations, the change in R² (cross-sectional analysis) and Bayesian information criterion (BIC) (longitudinal analysis) from the linear to the more complex models were calculated. The quadratic or polynomial regression in the cross-sectional analysis, marginally improved the variance in HR_max explained by age compared to the linear regression for the whole cohort (0.2%), moderate fit group (0.3%), and low fit group (0.8%). With no improvements in the high fit group. BIC did not improve for any CRF category in the longitudinal analysis. In conclusion, the minimal differences among linear, quadratic, and polynomial equations in the respective CRF groups, emphasizes the use of linear prediction equations to estimate HR_max.     

房产税改革的方案选择及财税效应分析

对房产持有环节开征房产税具有国际通用的合理性和合法性,房产税改革是新一轮国家财税体制改革的重要内容。对国内主要城市的房产税改革方案及其财税效应分析表明：采用无差别税率征税方案的优势在于减少征管成本、确保居民纳税义务的公平性,劣势在于造成纳税人税负过重、不利于调节财富分配差距;而按住房面积采用递进税率征税方案的优势在于能够调节贫富差距、体现“量能负担”原则,劣势在于容易被纳税人投机取巧而逃避高税率和监管。权衡利弊,“每人享受一定面积的减免,根据住房面积大小、基于公告价值或评估价值按不同税率征收”的方案,可作为今后房产税改革的主要方向。     

高强度运动对心脏的冲击影响及信号提取研究

设计实时的肌肉组织血氧量和瞬时心率无损同步检测方案与设备,为研究高强度运动心脏的冲击影响、探讨高强度运动中代谢规律提供测试手段。方法:采用连续双波长近红外光测量肌肉中血红蛋白与肌红蛋白含氧量的变化情况;采用芬兰SUUNTO心率带和自行设计的转发器及配套PC软件测量瞬时心率,进行了100m跑同步实测试验。结果:100m跑以无氧代谢为主。起跑后的前7s为无氧代谢的非乳酸功能,肌氧饱和度曲线变化不大。7s后开始消耗肌肉中储存的氧。结论:双波长近红外光组织氧测试法和运动心率无线实时采集系统能够正确实时同步地检测高强度运动时血氧和心率,揭示了高强度运动过程中肌肉中氧的运输与消耗及心率之间的动力学过程。     

体育用品企业如何应对人民币升值的冲击

在分析我国体育用品市场现状的基础上，研究了人民币汇率变动的趋势以及汇率的变动对体育用品企业的影响，探讨了面临人民币升值的压力，如何趋利避害，合理利用国外生产要素，降低生产成本．及时归还和调整外汇债务，借鉴外国经验，大力推进对外直接投资。     

省青少年比赛中篮球裁判员运动强度影响因素的研究

探讨比赛中篮球裁判员心率与年龄和体重等指标的关系;进一步比较不同级别篮球裁判员在比赛中生理指标的变化特征。对不同级别裁判员的赛中心率变化分析表明：在省青少年篮球比赛中,裁判级别对心率分布、最高心率和平均心率等指标无明显影响。相关分析表明篮球裁判员在省青少年比赛中的心率指标与年龄、体重以及级别之间无相关关系。     

短期力量练习对老年人肌肉力量和身体功能的影响

为了充分证实不同的力量练习计划对老年人体质健康影响的效果,通过对比高速率的变阻训练(HV)、由慢到快速率的等阻训练(CT)以及高速率的变阻练习与身体功能练习相结合(CB)的3种不同的短期力量练习计划对老年人的肌肉功能和身体活动能力的影响进行了实证性研究。研究结果显示:与控制组(CO)相比,HV组、CT组以及CB组的肌肉力量都有显著性的提高,而CO的力量呈轻微的下降趋势;每周两次的HV练习在提高力量和爆发性身体功能时,要优于CT和CB组;与HV和CT组相比,CB组对增加老年人的力量也是有效的,这个结果对于那些不愿意或不能频繁参加力量练习的老年人是一个重要提示。     

Thermoneutral immersion exercise accelerates heart rate recovery: A potential novel training modality

This study compared heart rate recovery (HRR) after incremental maximal exercise performed at the same external power output (P_ext) on dry land ergocycle (DE) vs. immersible ergocycle (IE). Fifteen young healthy participants (30?±?7 years, 13 men and 2 women) performed incremental maximal exercise tests on DE and on IE. The initial P_ext on DE was 25?W and was increased by 25?W/min at a pedalling cadence between 60 and 80?rpm, while during IE immersion at chest level in thermoneutral water (30°C), the initial P_ext deployment was at a cadence of 40?rpm which was increased by 10?rpm until 70?rpm and thereafter by 5?rpm until exhaustion. Gas exchange and heart rate (HR) were measured continuously during exercise and recovery for 5?min. Maximal HR (DE: 176?±?15 vs. IE 169?±?12?bpm) reached by the subjects in the two conditions did not differ (P?>?.05). Parasympathetic reactivation parameters (ΔHR from 10 to 300?s) were compared during the DE and IE HR recovery recordings. During the IE recovery, parasympathetic reactivation in the early phase was more predominant (HRR at Δ10–Δ60?s, P?<?.05), but similar in the late phase (HRR at Δ120–Δ300?s, P?>?.05) when compared to the DE condition. In conclusion, incremental maximal IE exercise at chest level immersion in thermoneutral water accelerates the early phase parasympathetic reactivation compared to DE in healthy young participants.     

花剑运动员技术训练与模拟比赛训练课的心率特征分析

以福建省花剑运动员为研究对象,对花剑运动员的技术训练课和模拟比赛课全程进行实时心率测试分析,认为模拟比赛训练课能达到实战训练强度的要求,有利于高水平运动员提高技战术的实战能力,技术训练课负荷强度较低,适合于技术水平较低的运动员,应根据不同技术水平的运动员合理安排技术训练课与模拟比赛训练课的比重。     

Effects of official youth taekwondo competitions on jump and strength performance

Abstract

The aim of this study was to investigate differences in athletes’ (7 females, 10 males) motor performances (countermovement jump and handgrip) before and after official youth (13–14 years) taekwondo matches. Exercise load was evaluated by means of the heart rate responses during the match. Independent of round and gender, during the competitions mean heart rate was 187 beats·min^?1 (s=11). During the match, the frequency of heart rate responses above 85% of an individual's maximum heart rate was 77% (s=27). Jump performances showed differences for gender (P=0.044; ES = 0.47) and its interaction with session (P=0.045; ES = 0.49). Female athletes’ post-match countermovement performances were no different from their pre-match performances (pre and post: 22 cm, s=2), whereas male athletes post-match performances (28 cm, s=6) were better than their pre-match performances (25 cm, s=6). Handgrip performances related to the body mass of the athletes showed main effects for session (P=0.017; ES = 0.20) and for gender (P=0.026; ES = 0.47), with no significant interaction. Male athletes showed higher handgrip values (5.8 N·kg^?1, s=0.6) than their female counterparts (5.1 N·kg^?1, s=0.7). For absolute grip strength performances, values were higher pre-match (290.3 N, s=61.4) than post-match (272.4 N, s = 58.3). The heart rate responses indicate that official youth taekwondo competition imposes a high load on athletes. In particular, post-match decreases in isometric grip strength suggest that coaches should better prepare their very young athletes to prevent reductions in muscle force during fighting. Considering that lower limb power remained unaffected or increased depending on gender, further research in this area is strongly recommended.