Effects of mild running on substantia nigra during early neurodegeneration

Moderate physical exercise acts at molecular and behavioural levels, such as interfering in neuroplasticity, cell death, neurogenesis, cognition and motor functions. Therefore, the aim of this study is to analyse the cellular effects of moderate treadmill running upon substantia nigra during early neurodegeneration. Aged male Lewis rats (9-month-old) were exposed to rotenone 1mg/kg/day (8 weeks) and 6 weeks of moderate treadmill running, beginning 4 weeks after rotenone exposure. Substantia nigra was extracted and submitted to proteasome and antioxidant enzymes activities, hydrogen peroxide levels and Western blot to evaluate tyrosine hydroxylase (TH), alpha-synuclein, Tom-20, PINK1, TrkB, SLP1, CRMP-2, Rab-27b, LC3II and Beclin-1 level. It was demonstrated that moderate treadmill running, practiced during early neurodegeneration, prevented the increase of alpha-synuclein and maintained the levels of TH unaltered in substantia nigra of aged rats. Physical exercise also stimulated autophagy and prevented impairment of mitophagy, but decreased proteasome activity in rotenone-exposed aged rats. Physical activity also prevented H₂O₂ increase during early neurodegeneration, although the involved mechanism remains to be elucidated. TrkB levels and its anterograde trafficking seem not to be influenced by moderate treadmill running. In conclusion, moderate physical training could prevent early neurodegeneration in substantia nigra through the improvement of autophagy and mitophagy.     

Effects of upper and lower body wearable resistance on spatio-temporal and kinetic parameters during running

ABSTRACT

Wearable resistance training involves added load attached directly to the body during sporting movements. The effects of load position during running are not yet fully established. Therefore, the purpose of this research was to determine spatio-temporal and kinetic characteristics during submaximal running using upper, lower and whole-body wearable resistance (1–10% body mass (BM)). Twelve trained male runners completed eight 2-min treadmill running bouts at 3.9 m/s with and without wearable resistance. The first and last bouts were unloaded, while the middle 6 were randomised wearable resistance conditions: upper body (UB) 5% BM, lower body (LB) 1%, 3%, 5% BM and whole body (WB) 5%, 10% BM. Wearable resistance of 1–10% BM resulted in a significant increase in heart rate (5.40–8.84%), but minimal impact on spatio-temporal variables. Loads of 5% BM and greater caused changes in vertical stiffness, vertical and horizontal force, and impulse. Functional and effective propulsive force (2.95%, 2.88%) and impulse (3.40%, 3.38%) were significantly (p < 0.05) greater with LB5% than UB5%. Wearable resistance may be used to increase muscular kinetics during running without negatively impacting spatio-temporal variables. The application of these findings will vary depending on athlete goals. Future longitudinal studies are required to validate training contentions.     

Effect of water ingestion on endurance capacity during prolonged running

This study examined the influence of water ingestion on endurance capacity during submaximal treadmill running. Four men and four women with a mean (± S.E.) age of 21.4 ± 0.7 years, height of 169 + 2 cm, body mass of 63.1 ± 2.9 kg and VO ₂ max of 51.1 ± 1.8 ml kg^?1 min^?1, performed two randomly assigned treadmill runs at 70% VO ₂ max to exhaustion. No fluid was ingested during one trial (NF‐trial), whereas a single water bolus of 3.0 ml kg^?1 body mass was ingested immediately pre‐exercise and serial feedings of 2.0 ml kg^?1 body mass were ingested every 15 min during exercise in a fluid replacement trial (FR‐trial). Run time for the NF‐trial was 77.7 ± 7.7 min, compared to 103 ± 12.4 min for the FR‐trial (P<0.01). Body mass (corrected for water ingestion) decreased by 2.0 ± 0.2% in the NF‐trial and 2.7 ± 0.2% in the FR‐trial (P<0.01), while plasma volume decreased by 1.1 ± 1.1% and 3.5 ± 1.1% in the two trials respectively (N.S.). However, these apparent differences in circulatory volume were not associated with differences in rectal temperature. Respiratory exchange ratios indicated increased carbohydrate metabolism (73% vs 64% of total energy expenditure) and suppressed fat metabolism after 75 min of exercise in the NF‐trial compared with the FR‐trial (NF‐trial, 0.90 ± 0.01; FR‐trial, 0.86 ± 0.03; P<0.01). Blood glucose concentrations were similar in both trials, while blood lactate concentrations were higher in the NF‐trial at the end of exercise (4.83 ± 0.34 vs 4.18 ± 0.38 mM; P<0.05). In summary, water ingestion during prolonged running improved endurance capacity.     

Effect of speed on local dynamic stability of locomotion under different task constraints in running

Abstract

A number of studies have investigated effects of speed on local dynamic stability of walking, although this relationship has been rarely investigated under changing task constraints, such as during forward and backward running. To rectify this gap in the literature, the aim of this study was to investigate the effect of running speed on local dynamic stability of forward and backward running on a treadmill. Fifteen healthy male participants took part in this study. Participants ran in forward and backward directions at speeds of 80%, 100% and 120% of their preferred running speed. The three-dimensional motion of a C7 marker was recorded using a motion capture system. Local dynamic stability of the marker was quantified using short- and long-term largest finite-time Lyapunov exponents (LyE). Results showed that short-term largest finite-time LyE values increased with participant speed meaning that local dynamic stability decreased with increasing speed. Long-term largest finite-time LyEs, however, remained unaffected as speed increased. Results of this study indicated that, as in walking, slow running is more stable than fast running. These findings improve understanding of how stability is regulated when constraints on the speed of movements is altered. Implications for the design of rehabilitation or sport practice programmes suggest how task constraints could be manipulated to facilitate adaptations in locomotion stability during athletic training.     

Effect of two different intensity distribution training programmes on aerobic and body composition variables in ultra-endurance runners

The aim of this study was to compare the effects of two different intensity distribution training programmes (polarized (POL) and threshold (THR)) on aerobic performance, strength and body composition variables in ultra-endurance runners. Twenty recreationally trained athletes were allocated to POL (n?=?11; age: 40.6?±?9.7 years; height: 175.4?±?7?cm; weight: 73.5?±?10.8?kg; fat mass 18.4?±?6.0%; VO₂max: 55.8?±?4.9?ml/kg/min) or THR group (n?=?9; age: 36.8?±?9.2 years; height: 178.5?±?4.2?cm; weight: 75.5?±?10.4?kg; fat mass 14.9?±?5.3%; VO₂max: 57.1?±?5.2?ml/kg/min) and performed the 12 weeks training programme. Both programmes had similar total time and load but a different intensity distribution (POL?=?79.8?±?2.1% in Zone 1; 3.9?±?1.9% in Zone 2; 16.4?±?1.5% in Zone 3; THR?=?67.2?±?4.6% in Zone 1; 33.8?±?4.6% in Zone 2; 0% in Zone 3). Body composition, isokinetic strength and aerobic running performance were measured before and after each programme. Both groups decreased fat mass after training (POL= Δ–11.2%; p?=?.017; ES?=?0.32; THR= Δ–18.8%; p?p?=?0.003; ES?=?0.71) and 12?km/h (Δ–4.5%; p?=?.026; ES?=?0.73) and running time to exhaustion (Δ2.4%; p?=?.011; ES?=?0.33). No changes were observed in strength and no significant differences were observed between the group in any variable. Compared with THR distribution, 12 weeks of POL training efficiently improves aerobic performance in recreational ultra-endurance runners.     

The impact of load on lower body performance variables during the hang power clean

This study examined the impact of load on lower body performance variables during the hang power clean. Fourteen men performed the hang power clean at loads of 30%, 45%, 65%, and 80% 1RM. Peak force, velocity, power, force at peak power, velocity at peak power, and rate of force development were compared at each load. The greatest peak force occurred at 80% 1RM. Peak force at 30% 1RM was statistically lower than peak force at 45% (p = 0.022), 65% (p = 0.010), and 80% 1RM (p = 0.018). Force at peak power at 65% and 80% 1RM was statistically greater than force at peak power at 30% (p < 0.01) and 45% 1RM (p < 0.01). The greatest rate of force development occurred at 30% 1RM, but was not statistically different from the rate of force development at 45%, 65%, and 80% 1RM. The rate of force development at 65% 1RM was statistically greater than the rate of force development at 80% 1RM (p = 0.035). No other statistical differences existed in any variable existed. Changes in load affected the peak force, force at peak power, and rate of force development, but not the peak velocity, power, or velocity at peak power.     

不同时间带运动减肥的比较

在低痛苦甚至无痛苦的前提下以控制能量摄入与适当运动的方法进行60天的减肥实验,比较晚饭前与晚饭后运动减肥的效果,发现运动之后再吃晚饭减肥的效果更好,体重指数多下降2.66(P<0.001)。建议减肥的人先进行约2h的运动,再吃晚饭,在餐前暗示减少对脂类、糖类食物的摄入。     

BMI、腰臀比和血压的不同对成年男子身体机能的影响分析

通过测试法和数理统计法等,探索BMI、腰臀比和血压的变化对成年男子身体机能的综合影响,旨在提高成年人的健康水平,为相关研究提供参考依据。     

Effects of footwear midsole thickness on running biomechanics

Shoe manufacturers launch running shoes with increased (e.g., maximalists) or decreased (e.g., minimalists) midsole thickness and claim that they may prevent running injury. Previous studies tested footwear models with different midsole thicknesses on the market but the shoe construct was not strictly comparable. Therefore, in the present study, we examined the effect of midsole thickness, from 1-mm to 29-mm, in a standard test shoe prototype on the vertical loading rates, footstrike angle and temporal spatial parameters in distance runners. Fifteen male habitual rearfoot strikers were recruited from local running clubs. They were asked to run on an instrumented treadmill in shoes with different midsole thicknesses. We found significant interactions between midsole thickness with vertical loading rates (p < 0.001), footstrike angle (p = 0.013), contact time (p < 0.001), cadence (p = 0.003), and stride length (p = 0.004). Specifically, shoes with thinner midsole (1- and 5-mm) significantly increased the vertical loading rates and shortened the contact time, when compared with thicker midsole shoes (25- and 29-mm). However, we did not observe any substantial differences in the footstrike angle, cadence and stride length between other shod conditions. The present study provides biomechanical data regarding the relationship between full spectrum midsole thicknesses and running biomechanics in a group of rearfoot strikers.     

男子散打运动员赛前降体重对运动能力和体液离子的影响

以6名上海优秀男子散打运动员为研究对象,对赛前体重控制、运动能力和体液离子变化情况进行研究,每周3次体脂率测试;每2周测试1次无氧运动能力和体液离子情况。结果显示,第3周体重和体脂率显著下降(P<0.05),第5周体重发生高度显著变化(P<0.01),体脂率和瘦体重显著下降(P<0.05);无氧运动能力在整个控重过程无显著变化(P>0.05);第3周Na+升高非常显著(P<0.01),Ca2+显著升高(P<0.05),CO2CP下降(P<0.05),第5周Na+浓度有所下降但仍高于控重前(P<0.05),Ca2+显著升高(P<0.05),CO2CP明显下降(P<0.01)。研究表明通过延长整理活动和增加有氧训练课可以实现运动员控重以消耗脂肪为主的目标,能够保证运动员无氧能力不损失,通过电解质饮料补充能够维持队员机体内环境的稳定。     

Effects of medium- and long-distance running on cardiac damage markers in amateur runners: a systematic review,meta-analysis,and metaregression

BackgroundTo finish an endurance race, athletes perform a vigorous effort that induces the release of cardiac damage markers. There are several factors that can affect the total number of these markers, so the aim of this review was to analyze the effect of endurance running races on cardiac damage markers and to identify the factors that modify the levels of segregation of these cardiac damage markers.MethodsA systematic search of PubMed, Web of Science, and the Cochrane Library databases was performed. This analysis included studies where the acute effects of running races on cardiac damage markers (troponin I and troponin T) were analyzed, assessing the levels of these markers before and after the races.ResultsThe effects of running races on troponin I (mean difference = 0.0381 ng/mL) and troponin T (mean difference = 0.0256 ng/mL) levels were significant. The ages (R² = 14.4%, p = 0.033) and body mass indexes (R² = 14.5%, p = 0.045) of the athletes had a significant interaction with troponin I. In addition, gender, mean speed, time to finish the race, and type of race can affect the level of cardiac damage markers.ConclusionEndurance running races induce the release of cardiac-damage markers that remain elevated for at least 24 h after the races. In addition, young male athletes with high body mass indexes who perform races combining long duration and moderate intensity (i.e., marathons) release the highest levels of cardiac damage markers. Physicians should take into consideration these results in the diagnosis and treatment of patients admitted to the hospital days after finishing endurance running races.     

不同极简指数跑鞋对髌股关节受力特征的影响

聚焦跑步时髌股关节生物力学特征,探究穿着不同极简指数(MI)跑鞋对髌股关节接触力、应力等的即刻影响。选取15名习惯后跟着地的健康男性跑者,分别穿着两种MI跑鞋(MI 86%极简跑鞋和MI 26%缓冲跑鞋),使用Vicon红外运动捕捉系统、Kistler三维测力台同步采集3.33 m/s(速度变化范围±5%)跑速下的膝、踝关节运动学和地面反作用力,通过逆向动力学等计算股四头肌肌力、髌股关节接触力、髌股关节接触面积以及髌股关节接触应力。结果显示:两种跑鞋条件下的冲击力峰值和蹬地力峰值均无明显差异。与缓冲跑鞋相比,穿着极简跑鞋跑步时,膝关节最大屈曲角度显著降低(P<0.01);髌股关节接触面积显著减小(P<0.01);膝关节伸肌峰值力矩显著下降(P<0.01);髌股关节接触力和应力峰值均显著减小(P<0.05)。研究表明,相比缓冲跑鞋,穿着极简跑鞋在未影响触地后冲击力峰值的同时,通过降低伸膝力矩大幅度减少髌股关节接触力(下降17.02%)、降低髌股关节接触应力,从而有效改善支撑期髌股关节负荷,为进一步减小髌股关节疼痛综合征风险提供可能。     

赛前不同方式降体重对女子摔跤运动员身体机能的影响

运用文献资料法、访谈法、实验法、数理统计法等,对辽宁省女子摔跤运动员赛前分别采取快速降体重和慢速降体重前后身体机能状态进行监测,分析不同降体重方式下运动员身体机能状态的变化特点,旨在为女子摔跤运动员赛前合理降体重及实时监控运动员的机能状态提供参考.     

Effects of running experience on coordination and its variability in runners

The purpose of this study was to examine the differences in coordination variability in running gait between trained runners and non-runners using continuous relative phase (CRP) analysis. Lower extremity kinematic data were collected for 22 participants during the stance phase. The participants were assigned to either a runner or non-runner group based on running volume training. Segment coordination and coordination variability were calculated for selected hip–knee and knee–ankle couplings. Independent t-tests and magnitude-based inferences were used to compare the 2 groups. There were limited differences in the CRP and its variability among runners and non-runner groups. The runners group achieved moderately lower coordination compared with non-runners group in the phase angle for hip abduction/adduction and knee flexion/extension. The runners tended to show moderately lower coordination variability in the phase angle for knee flexion/extension and subtalar inversion/eversion in comparison to non-runners group. These results suggested that levels of experience as estimated from weekly training volume had little influence on coordination and its variability.     

The effects of eccentric exercise-induced muscle damage on running kinematics at different speeds

Abstract

This study investigated the effects of knee localised muscle damage on running kinematics at varying speeds. Nineteen young women (23.2 ± 2.8 years; 164 ± 8 cm; 53.6 ± 5.4 kg), performed a maximal eccentric muscle damage protocol (5 × 15) of the knee extensors and flexors of both legs at 60 rad · s^-1. Lower body kinematics was assessed during level running on a treadmill at three speeds pre- and 48 h after. Evaluated muscle damage indices included isometric torque, muscle soreness and serum creatine kinase activity. The results revealed that all indices changed significantly after exercise, indicating muscle injury. Step length decreased and stride frequency significantly increased 48 h post-exercise only at the fastest running speed (3 m · s^-1). Support time and knee flexion at toe-off increased only at the preferred transition speed and 2.5 m · s^-1. Knee flexion at foot contact, pelvic tilt and obliquity significantly increased, whereas hip extension during stance-phase, knee flexion during swing-phase, as well as knee and ankle joints range of motion significantly decreased 48 h post-exercise at all speeds. In conclusion, the effects of eccentric exercise of both knee extensors and flexors on particular tempo-spatial parameters and knee kinematics of running are speed-dependent. However, several pelvic and lower joint kinematics present similar behaviour at the three running speeds examined. These findings provide new insights into how running kinematics at different speeds are adapted to compensate for the impaired function of the knee musculature following muscle damage.     

优秀男子拳击运动员赛前减控体重及身体成分变化的研究

为掌握优秀拳击运动员大赛前减控体重及身体成分的变化情况,连续监测7名拳击运动员赛前4周安静空腹状态下的身体成分,结果显示:运动员体重呈平稳逐渐下降的态势,但身体成分中以减掉身体细胞内液为主,以降低脂肪为辅,体脂率在赛前依然偏高。提示运动员在赛前基本达到或接近参赛体重,但体脂率依然处在较高水平。     

Independent effects of step length and foot strike pattern on tibiofemoral joint forces during running

The purpose of this study was to examine the effects of step length and foot strike pattern along with their interaction on tibiofemoral joint (TFJ) and medial compartment TFJ kinetics during running. Nineteen participants ran with a rear foot strike pattern at their preferred speed using a short (?10%), preferred, and long (+10%) step length. These step length conditions were then repeated using a forefoot strike pattern. Regardless of foot strike pattern, a 10% shorter step length resulted in decreased peak contact force, force impulse per step, force impulse per kilometre, and average loading rate at the TFJ and medial compartment, while a 10% increased step length had the opposite effects (all P < 0.05). A forefoot strike pattern significantly lowered TFJ and medial compartment TFJ average loading rates compared with a rear foot strike pattern (both <0.05) but did not change TFJ or medial compartment peak force, force impulse per step, or force impulse per km. The combination of a shorter step length and forefoot strike pattern produced the greatest reduction in peak medial compartment contact force (P < 0.05). Knowledge of these running modification effects may be relevant to the management or prevention of TFJ injury or pathology among runners.     

两种习惯性着地方式对跑步支撑期下肢动力学特征的影响

目的：探究习惯后足着地者和习惯前足着地者在跑步支撑期下肢动力学的不同。方法：采用 Kistler三维测力台（采集力学指标,1 000 Hz）采集受试者跑步支撑期（测试足从足着地到足离地）的动力学数据。结果：习惯后足着地组（RFS）在支撑时间上比习惯前足着地组（FFS）的时间微长,但二者不具有显著差异（P>0.05）;RFS组在支撑期内外方向的最小值和最大值均小于FFS组,且呈显著差异（P＜0.05）;RFS组在支撑期前后方向的最小值（即制动力峰值）和最大值（即加速力峰值）均要高于FFS组,且呈显著差异（P＜0.05）;FFS组在支撑期垂直方向的最大峰值力和第一载荷率均高于RFS组,但不具有显著差异,且出现峰值时间无显著差异（P＞0.05）。结论：跑步时不同的着地方式影响了下肢的生物力学特征,习惯后足着地者跑步支撑期下肢动力学特征与习惯前足着地者主要在内外方向和前后方向上具有一定的差异。     

Upper and lower limb loading during weight-bearing activity in children: reaction forces and influence of body weight

Weight bearing (WB) activity is important for healthy skeletal development. The magnitude of loading during WB activities, especially upper limb impacts, has yet to be quantified in children. This study quantifies ground reaction forces (GRF) experienced by children performing WB activities and examines the contribution of body weight (BW) to GRF. Fifty children, aged 8–12 were recruited (34 males). GRF were measured using force plates during 20 upper and lower limb activities (such as landing on the feet and hands). Sex differences in GRF and associations between peak force and BW were examined using independent sample t-tests and linear regressions (p < 0.05), respectively. Lower limb GRF varied from 2-6x BW with no significant sex differences. GRF during upper limb activities varied from 1/3–1.7x BW with males experiencing significantly greater GRF for 25% of activities. BW was significantly associated with peak force in almost all activities; however, GRF variation explained by BW was wide-ranging across activities and not dependent on limb or activity type (static vs dynamic). Therefore, factors other than BW, such as technique, may be important in determining forces experienced by children performing WB activity and should be considered when choosing activities for WB activity interventions.