大成拳发力原理探析

大成拳自问世以来,其拳学理论、训练方法自成体系。关于大成拳发力机理的系统理论问题,不仅为拳学界关心,也与各类体育运动项目相关联。文章结合多年的练拳体认,并借鉴当今科研领域的研究成果,从人体生理学、运动生物力学以及传统力学等方面进行分析。研究表明,大成拳通过站桩静态训练,增强了人体肌肉的协调性和整体爆发力;人体全部活动、微动关节处的收肌在神经的支配下,做持续收缩和放松,结合逆呼吸法的作用,使身体重心相对抬升,形成以自身体重为重力势能的单重发力状态;大成拳立体力,即在惯性和地心引力的共同作用下的特有发力方法。     

先礼后兵：武术与军事的和谐诉求

当今和谐社会的大环境下,武术经常被误解为暴力、不和谐,军事行为也被视为阻碍世界和平发展的重大因素。文章运用文献资料法分别从不同方面对武术和军事进行分析,探讨其内在本质和最终价值诉求,得出武术与军事结伴而生,同源异流,其最终诉求都是和谐。     

高校实施武术段位制课程教学的SWOT分析

武术段位制既有以考试内容系统传承武术技术和武术文化的作用,又有着以考试标准引导科学健身和逐步提高武术水平的作用。因此,武术段位制引入高校武术教学也是必然趋势。文章以武术段位制课程教学为研究内容,运用SWOT分析法对当前高校武术段位制课程实施的内部环境（优势、劣势）和外部条件（机遇、风险）进行分析,提出完善考评制度、加强段位制课程师资队伍建设、充实段位制课程教材、统筹段位考评机构等手段,旨在为武术段位制课程在高校更好开展,更广泛地被运用于更多高校的武术教学实践提供理论依据,为推广武术段位制提供更好的服务。     

Estimation of Errors in Force Platform Data

Abstract

Young, healthy varsity swimmers were studied over a period of 14 months with regard to the effect of a typical training and competitive collegiate swimming program on plasma cholesterol and phospholipids. Chemical analyses on blood cholesterol and phospholipids were made and compared for competitive and noncompetitive seasons. A dietary analysis was also made during the competitive season. In both the original and subsequent study involving the current (1960–61) varsity swimmers analyses were made of the acute effect of physical exertion on plasma cholesterol and phospholipids.

The exercise, used for conditioning varsity swimming athletes did not significantly lower blood cholesterol and phospholipids. However, this result is not necessarily at variance with the view of some investigators that exercise does exert a hypocholesterilizing effect. Several factors are discussed which are thought to have influenced ultimate results.     

BASES 2006: “From education to application”

The dependence of power on aerobic and anaerobic energy metabolism and on force production was studied in maximal leg exercise. National and international level male rowers (n = 9) performed four modified (legs‐only) rowing ergometer exercises: a progressive test, 2‐min (T2), 12‐min (T12) and 6‐min (T6) all‐out tests. In T2, significant correlations were observed between power in T2 (P_T2) and oxygen debt (r = 0.83, P<0.05) and between P_T2 and average force production (F_av) during the last 30 s (r = 0.85, P<0.05). These parameters explained 93% of the variation in P_T2. The highest correlations between power in T6 (P_T6) and physiological parameters were as follows: maximal oxygen uptake (VO₂ max: r = 0.87, P<0.01), blood bicarbonate concentration before the test ([HCO^‐ _3before]: r=0.85, P<0.05) and blood lactate concentration on anaerobic threshold (BL_anT: r= —0.82, P<0.05). Together, these parameters explained 92% of the variation in P_T6. In T12, the total power (P_T12) correlated with power of anaerobic threshold #OPP_ANT’. r = 0.95, P< 0.001) and with the highest VO₂ value in this test (VO₂ peak: r = 0.92, P<0.001). These two parameters explained 96% of the variation in P_T12.

The decrease of at least one of the force parameters during each test was taken as a sign of fatigue. The decline in force was compensated for by an increase in stroke rate at the end of T6 and T12 (P<0.01, P<0.001). Consequently, the power remained unchanged or even increased at the end of T6 and T12. The term ‘power endurance’ is introduced to describe the ability to resist and to compensate for local muscular fatigue.     

String vibration dampers do not reduce racket frame vibration transfer to the forearm

In this study, we examined the effect of string vibration damping devices on reducing racket frame vibration transfer to the forearm. Twenty participants volunteered to hold a tennis racket stationary in a forehand and backhand stroking position while tennis balls were fired at 20 m?·?s^?1 towards two impact locations, the node of vibration and the dead spot. A three-way analysis of variance with repeated measures on damping condition, impact location and stroke condition was performed on the data. The resonant frequency of the hand-held racket was found to be ～120 Hz. No significant differences in amplitude of vibration at the resonant frequency were found for the wrist or the elbow when damped and non-damped impacts were compared. Impacts at the dead spot produced greater amplitudes of vibration (P <?0.01) but no interaction between impact location and string dampers was evident. The string dampers had no effect on the grip force used or the muscle electrical activity in the forearm after impact. In conclusion, we found that string dampers do not reduce the amount of racket frame vibration received at the forearm. We suggest that string dampers remain a popular accessory among tennis players because of their acoustic effects and psychological support rather than any mechanical advantage.     

Effects of stance width on performance and postural stability in national-standard pistol shooters

Abstract

The aim of the present study was to determine whether changing stance width would result in a corresponding change in postural and/or pistol stability. Twelve national-standard male air pistol shooters performed 10 shots each at five stance widths (30 cm, 45 cm, 60 cm, 75 cm, and 90 cm). Postural stability was determined by measuring centre-of-pressure changes with a dual force-platform system. Shooting mechanics measures were determined by a NOPTEL ST-2000 optoelectronic training system. Medial-lateral centre-of-pressure excursion (F _4,44 = 7.17, P < 0.001, effect size = 0.99) and speed (F _4,44 = 77.03, P < 0.001, effect size = 3.88) were reduced as stance width decreased. Centre of gravity fine (the percentage of time held within an area the size of the ten-ring) improved during narrower stance widths (F _4,32 = 12.49, P < 0.001, effect size = 0.71). Our findings suggest that stance width affects postural and pistol stability in national-standard air pistol athletes. Moreover, the current method of suggesting a wider stance to improve shooting performance should be reconsidered and perhaps air-pistol shooters should use a 30-cm stance width to improve postural stability and shooting performance.     

The force–time profile of elite front crawl swimmers

Abstract

In this study, we used recently developed technology to determine the force–time profile of elite swimmers, which enabled coaches to make informed decisions on technique modifications. Eight elite male swimmers with a FINA (Federation Internationale de Natation) rank of 900+ completed five passive (streamline tow) and five net force (arms and leg swimming) trials. Three 50-Hz cameras were used to video each trial and were synchronized to the kinetic data output from a force-platform, upon which a motorized towing device was mounted. Passive and net force trials were completed at the participant's maximal front crawl swimming velocity. For the constant tow velocity, the net force profile was presented as a force–time graph, and the limitation of a constant velocity assumption was acknowledged. This allowed minimum and maximum net forces and arm symmetry to be identified. At a mean velocity of 1.92 ± 0.06 m · s^?1, the mean passive drag for the swimmers was 80.3 ± 4.0 N, and the mean net force was 262.4 ± 33.4 N. The mean location in the stroke cycle for minimum and maximum net force production was at 45% (insweep phase) and 75% (upsweep phase) of the stroke, respectively. This force–time profile also identified any stroke asymmetry.     

The 1985 C. H. McCloy Research Lecture Practical Problems in Exercise Physiology Research

Abstract

This paper examines the contribution of exercise physiology research to improvements in sports performance. By using illustrations from studies on competitive swimmers, attempts have been made to show the need to develop tests that evaluate the factors essential for success in sports. Such testing should be used to describe the strengths and weaknesses of the athlete, and to offer the athlete and coach valid information to gauge the benefits of training. Aside from the value of monitoring the adaptations to sports training, the primary role of physiological research in sports should be to solve problems that will ultimately aid athletes to achieve their full potential. This paper will conclude with examples of problem solving research and its contribution to performance.