Physiological responses in different intensities of resistance exercise – Critical load and the effects of aging process

Aim was to identify critical load (CL) in young and elderly apparently healthy male cohorts. To contrast the metabolic, cardiovascular and perceptual responses on CL according to age. We evaluated 12 young (23 ± 3 years) and 10 elderly (70 ± 2 years) apparently healthy active males, who underwent: (1) 1 repetition maximum (1RM) test on a 45° Leg Press; (2) on different days, three high-intensity resistance exercise constant load tests (60%, 75% and 90% 1RM) until fatigue (Tlim). Absolute values of both the CL asymptote and curvature constant (kg) were significantly lower in elderly subjects (P < 0.05). In contrast, elderly subjects demonstrated a significantly higher number of repetitions at CL when compared with young subjects (P < 0.05). As expected, oxygen uptake (VO₂) and heart rate (HR) during maximal aerobic exercise testing were significantly reduced in older subjects. However, percent-predicted aerobic capacity were higher in older subjects (P < 0.05). In addition, blood lactate ([La^?]) corrected to Tlim and rating of perceived exertion values were greater in younger subjects at all intensities (P < 0.05). These findings, despite reduced force production in older subjects, endurance-related parameters are well preserved according to age-adjusted percent-predicted values in apparently healthy males.     

Can sit-to-stand muscle power explain the ability to perform functional tasks in adults with severe obesity?

This study examined the relationship between sit-to-stand (STS) power and physical function in adults with severe obesity. Thirty-eight adults (age: 44 ± 12 years; body mass index [BMI]: 45.2 ± 7.8 kg/m²) completed evaluations of STS power, strength and functional performance. STS power was measured with a wearable inertial sensor, strength was assessed with the isometric mid-thigh pull, and function was measured with the timed up-and-go (TUG), six-minute walk test (6MWT) and 30-s chair STS. Power and strength (normalised to body mass) entered regression models in addition to age, gender, BMI and physical activity (daily step count). Power displayed large univariate associations with TUG (r = 0.50) and 30-s chair STS (r = 0.67), and a moderate association with 6MWT (r = 0.49). Forward stepwise regression revealed that power independently contributed to TUG (β = ?0.40, p = 0.010), 30-s chair STS (β = 0.67, p < 0.001) and 6MWT performance (β = 0.27, p = 0.007). Power also appeared to be a superior determinant of function compared with strength. Power generated via the STS transfer largely underpins the ability to perform functional tasks in adults with severe obesity, although intervention studies are required to investigate a potentially causal relationship.     

Validity and reliability of a low-cost dynamometer to assess maximal isometric strength of upper limb

Muscle imbalance and deficit are key parameters for guiding rehabilitation and sports sessions and avoiding injuries. However, the high cost and non-portable nature of most instruments employed for muscle strength assessment frequently hamper an affordable evaluation in field conditions. This study evaluated the validity and reliability of a low-cost digital dynamometer to assess the maximal isometric strength of upper limb muscles. Fourteen physically active volunteers performed the main movements of the upper limb at maximal isometric strength: flexion-extension, internal-external rotation and abduction-adduction of the shoulder; and flexion-extension of both elbow and wrist. Validity was examined by comparing the strength values from the low-cost digital dynamometer and those measured by an isokinetic dynamometer, assumed as the gold standard. The correlation between both devices was perfect (r > 0.913), while Bland-Altman plots showed absolute agreement between both devices, the maximum range of the values of bias was ?0.99–1.00 N in wrist extension. Inter-tester and intra-tester reliability were excellent for all movements (ICC ≥ 0.855). The low-cost digital dynamometer showed strong validity and excellent reliability in assessing maximal isometric strength during the main movements of the upper limb. Professionals may use it for an affordable isometric muscle strength assessment in field situations.     

我国男生引体向上“零”分探因:基于三角互证的研究策略

我国多数男生引体向上得"零"分,使上肢力量测评出现"地板效应"。采用量化研究和质性研究两种范式提高研究效度。量化研究对学生体质与健康调研数据和监测数据进行方差分析、多重比较和回归分析,结果表明：（1）每5~10年,男生的握力、体重、身高、BMI、引体向上均值差异显著;（2）年龄、握力、体重、身高、BMI分别显著预测引体向上成绩,体重和握力是影响我国男生引体向上成绩的主要影响因素。质性研究结果表明,引体向上"零"分主要有四个方面的原因：体重增长难挡,力量增长受限,个体认知偏差,社会支持薄弱。结论：我国男生引体向上"零"分的首要原因是体重增长较快,其次,主要肌群绝对力量和耐力增长不足,男生对引体向上的认知有偏差,学校、家长、社会支持较弱;借助政策控制体重、发展肌力、完善测评标准、促进男生积极练习引体向上十分重要。     

第31届奥运会男篮参赛球队攻防能力研究

采用文献资料法、录像观察法和秩和比法等,对参加31届奥运会男篮比赛球队的攻防能力进行综合量化评价,并将中国男篮与对手的攻防能力指标进行对比分析.结果显示:中国男篮进攻RSR处于D级,在得分、助攻、3分球命中率与罚球命中率上,与对手存在非常显著性差异,在失误数、进攻篮板、3分球出手数上与对手存在显著性差异;中国男篮防守RSR处于D级,防守篮板数比对手少,而失分和犯规数比对手多,且在犯规数上与法国男篮存在显著性差异;中国男篮攻防RSR处于E级;球队最终排名与进攻RSR值和攻防RSR值之间存在非常显著性相关.     

Kinematic analysis of the drag flick in field hockey

Attaining high speed of the stick head and consequently of the ball is essential for successful performance of the drag flick in field hockey, but the coordination pattern used to maximise stick head speed is unknown. The kinematics of the drag flick was studied in ten elite hockey players who performed twenty shots each towards a target located 1.5 m high. A 150 Hz active marker motion analysis system was used, alongside two force plates to detect foot touchdown. Angular velocity and contribution to stick endpoint speed of upper body joints were analysed. Repeated measures ANOVA was used to compare timing of onset and peak angular velocities between joints. Participants used a kinematic pattern that was close to a proximal-to-distal sequence. Trunk axial rotation and lateral rotation towards the target, right wrist flexion and left wrist extension were the main contributors to stick endpoint speed. Coaches should emphasise trunk rotations and wrist flexion and extension movements for maximising stick head speed. Given the high level of the participants in this study, the coordination of joints motions, as reported here, can serve as a guideline for drag flick training.     

Effects of heat acclimation on hand cooling efficacy following exercise in the heat

This study examined the separate and combined effects of heat acclimation and hand cooling on post-exercise cooling rates following bouts of exercise in the heat. Seventeen non-heat acclimated (NHA) males (mean ± SE; age, 23 ± 1 y; mass, 75.30 ± 2.27 kg; maximal oxygen consumption [VO₂ max], 54.1 ± 1.3 ml·kg^?1·min^?1) completed 2 heat stress tests (HST) when NHA, then 10 days of heat acclimation, then 2 HST once heat acclimated (HA) in an environmental chamber (40°C; 40%RH). HSTs were 2 60-min bouts of treadmill exercise (45% VO₂ max; 2% grade) each followed by 10 min of hand cooling (C) or no cooling (NC). Heat acclimation sessions were 90–240 min of treadmill or stationary bike exercise (60–80% VO₂ max). Repeated measures ANOVA with Fishers LSD post hoc (α < 0.05) identified differences. When NHA, C (0.020 ± 0.003°C·min^?1) had a greater cooling rate than NC (0.013 ± 0.003°C·min^?1) (mean difference [95%CI]; 0.007°C [0.001,0.013], P = 0.035). Once HA, C (0.021 ± 0.002°C·min^?1) was similar to NC (0.025 ± 0.002°C·min^?1) (0.004°C [?0.003,0.011], P = 0.216). Hand cooling when HA (0.021 ± 0.002°C·min^?1) was similar to when NHA (0.020 ± 0.003°C·min^?1) (P = 0.77). In conclusion, when NHA, C provided greater cooling rates than NC. Once HA, C and NC provided similar cooling rates.     

我国龙狮运动可持续性发展战略研究——基于SWOT矩阵组合分析

摘要：我国舞龙舞狮运动从民间节气活动走向竞技舞台已20多年来的发展,随着时代的发展,未来龙狮运动发展战略究竟怎样？主要采用文献资料法、访谈法和数理统计法等研究方法,引用SWOT态势分析法,对我国龙狮运动可持续性发展进程中自身强势和劣势、发展中存在的问题、未来面临的发展机会及外界影响因素进行分析,从宏观上为我国龙狮运动可持续发展提供一个崭新的视角。研究表明,中国龙狮运动可持续发展战略路径：1）优势-机会组合分析表明,利用学校教育资源,扩大度发展大中学校龙狮队伍建设,提升龙狮运动在青少年中的认知能力;加强龙狮教练员、裁判员的师资培养;2)劣势-机会组合分析表明,加大龙狮科研理论体系研究力度,提升我国龙狮运动的理论与实践并驾齐驱;利用网络+平台,加大推广和宣传龙狮运动力度;3)优势-威胁组合分析表明,加强国际间的交流与合作,进一步挖掘整理龙狮运动的时代内涵,加强对龙狮文化的保护和推广工作,完善现行的竞赛制度;4)劣势-威胁组合分析表明,龙狮走市场、产业等多元化渠道,建立完善的器材标准化,弘扬龙狮传统文化。有利于把握竞技龙狮发展的特点和规律,为我国竞技龙狮运动可持续性发展提供一定的参考依据。     

新常态下我国体育教育本科专业发展的战略管理研究

研究目的:运用SWOT分析、文献资料等方法,对新常态下我国体育教育本科专业进行研究,从它的内、外部的优势和劣势进行具体分析.结果:外部环境中党和国家政策空前重视;仍需进一步扩大高校办学自主权;经济增速下滑、高校扩招,老龄化社会的到来,使得专业需求相对不足.从体育教育本科专业内部来说中国特色的高等教育体制统筹下的体育教育学科优势和体育教育本科专业内部资源的优化和内在发展动力;各个高校专业培养模式改革力度不够、教学成本较高、专业建设视角不够全面,专业培养方案、课程设置等需要深入改革,国家应从结构、布局、质量、效益等外部因素对该专业进行全国统筹,各高校应根据自身的设施条件、师资力量、区域特点,突出特色,服务于地方.结论:教育主管部门应加强师资培训,利用高校内部学科之间的相互交叉、渗透,培养多能一专的复合型体育人才.     

第64届美国运动医学会年会关于“运动益处的生物网络”研究热点与趋势

摘要：概述美国运动医学第64th年会的主要内容和目标;归纳“机体对运动反应/适应的生物网络”研究的报告热点;介绍美国国立卫生院资助项目,“人类体力活动的分子传感器”的研究设计和组成。建立各取所长、分工合作的研发联盟是进行运动促进健康分子机制研究的必要途径;基于集合最新研究技术和分析方法,从宏观到微观再到宏观,从整体到局部再到整体的整合性系统实验设计是链接运动益处与其作用机制的桥梁。在未来,该领域的研究成果不仅仅是精准运动的实现、运动依存性的提高和对慢性病的辅助治疗,同时如果能够发现传递运动益处的分子,研发成产品,这必将会为人类健康产生深远影响。