The effect of minimal shoes on arch structure and intrinsic foot muscle strength

BackgroundThis prospective study explored the effects of endurance running (ER) in minimal versus standard running shoes on the foot's superficial layer intrinsic muscles and the function of the longitudinal arch. Our hypothesis was that running in minimal shoes would cause hypertrophy in these muscles and lead to higher, stronger, stiffer arches.MethodsThe hypothesis was tested using a sample of 33 healthy runners randomized into two groups, a control group shod in traditional running footwear and an experimental group shod in minimal support footwear, whose feet were scanned in an MRI before and after a 12-week training regime. Running kinematics as well as arch stiffness and height were also assessed before and after the treatment period.ResultsAnalysis of anatomical cross-sectional areas and muscle volumes indicate that the flexor digitorum brevis muscle became larger in both groups by 11% and 21%, respectively, but only the minimally shod runners had significant areal and volumetric increases of the abductor digiti minimi of 18% and 22%, respectively, and significantly increased longitudinal arch stiffness (60%).ConclusionThese results suggest that endurance running in minimal support footwear with 4 mm offset or less makes greater use of the spring-like function of the longitudinal arch, thus leading to greater demands on the intrinsic muscles that support the arch, thereby strengthening the foot.     

Comparison of EMG activity during stable and unstable push-up protocols

Abstract

This experiment examined muscle activation measured using electromyography (EMG) during a standardized push-up performed on stable and unstable surfaces. Fifteen highly trained participants performed four push-ups: standard (hands and feet on the floor), either the hands or feet on an unstable surface (single instability), and with both hands and feet on unstable surfaces (dual instability). Unstable surfaces were created using a stability ball and an extreme balance board. EMG activity was recorded from three core stabilizers (erector spinae, rectus abdominus and internal obliques), one prime mover (triceps), and one lower body stabilizer (soleus). The EMG time series were smoothed using a 10-point moving average and root mean squares (RMS) were calculated for the entire time series. The results showed that push-ups performed with dual instability had significantly greater EMG activation compared to single instability or the stable push-up. In addition, as instability increased, there was a greater amount of muscle activation for the core stabilizers, prime movers and lower body stabilizers. The findings are consistent with the position that unstable surfaces in conjunction with standard exercises can be used to increase activation of core trunk stabilizers. This may in turn provide increased trunk strength and greater resistance to injury.     

Lower eccentric hamstring strength and single leg hop for distance predict hamstring injury in PETE students

Abstract

Hamstring injuries have not been under research in physical education teacher education (PETE) students so far. Within the frame of the development of an injury prevention program, for this study we conducted an analysis of modifiable risk factors for hamstring injuries in PETE students. Hamstring injuries of 102 freshmen bachelor PETE students were registered prospectively during one academic year. Eighty-one students completed maximum muscle strength tests of hip extensors, hamstrings, quadriceps (isometric) and hamstrings (eccentric) at the start of the academic year. Sixty-nine of the latter completed a single leg hop for distance (SLHD). Risk factors for hamstring injuries were statistically detected using logistic regression. Sixteen hamstring injuries (0.16 injuries/student/academic year; 0.46 injuries/1000 h) occurred to 10 participants. Eight cases were included in the risk factor analysis. Lower eccentric hamstring strength (odds ratio (ODD) = 0.977; p = 0.043), higher isometric/eccentric hamstring strength ratio (ODD = 970.500; p = 0.019) and lower score on the SLHD (ODD = 0.884; p = 0.005) were significant risk factors for hamstring injury. A combination of eccentric hamstring strength test and SLHD could give a good risk analysis of hamstring injuries in PETE students. This might offer great perspectives for easily applicable screening in a clinical setting.     

核心肌群训练对腰椎间盘突出症的改善作用

探讨核心肌群训练在腰椎间盘突出症治疗中的价值。对120名腰椎间盘突出症患者进行了5个月的核心肌群训练。结合螺旋CT、MRI造影技术对患处进行分析对比。结果表明实验组患者生理曲线改善程度显著高于参照组(P<0.05),实验组患者腰部疼痛感大腿麻木感较参照组有较大明显改善(P<0.01)。实验结论:通过核心肌群训练能够明显改善腰椎间盘周围韧带的牵张力消除肌肉粘连稳定腰椎等积极作用,对预防和治疗腰椎间盘突出症,防止再次复发具有重要的临床价值。     

Intra- and inter-rater reliability of the rate of force development of hip abductor muscles measured by hand-held dynamometer

The aim of this study was to clarify the intra- and inter-rater reliability of the rate of force development in hip abductor muscle force measurements using a hand-held dynamometer. Thirty healthy adults were separately assessed by two independent raters on two separate days. Rate of force development was calculated from the slope of the force-time curve that was divided into four time intervals (50, 100, 200, and 300 ms). The highest values of the three trials were used for statistical analysis. The intra-class correlation coefficient with a 95% confidence interval, standard error of measurement, and minimal detectable change at the 95% confidence level were calculated for each interval. For assessment of systematic error, Bland-Altman analysis was used. The results indicated that intra- and inter-rater reliability of the highest values at all intervals were sufficient (intra-class correlation coefficient > .7). The Bland-Altman analysis did not show systematic error in either reliability measure.     

Reliability assessment and correlation analysis of 3 protocols to measure trunk muscle strength and endurance

Different methods have been developed to quantify trunk muscle strength and endurance. However, some important protocol characteristics are still unclear, hindering the selection of the most suitable tests in each specific situation. The aim of this study was to examine the reliability and the relationship between 3 representative tests of the most common type of protocols used to assess trunk muscle strength and endurance. Twenty-seven healthy men performed each test twice spaced 1 month apart.Trunk strength and endurance were evaluated with an isokinetic dynamometer and 2 field tests including Biering-Sørensen test and Flexion–rotation trunk test.

All tests showed a good relative consistency (intraclass correlation coefficient [ICC]> 0.75), except for the isokinetic endurance variables which had low–moderate reliability (0.37 < ICC > 0.65). Absolute reliability seemed slightly better in the isokinetic protocol than in the field tests, which showed about 12% of test–retest score increase. No significant correlations were found between test scores.

After a familiarisation period for the field tests, the 3 protocols can be used to obtain reliable measures of trunk muscle strength and endurance. Based on the correlation analysis, these measures are not related, which highlights the importance of selecting the most suitable trunk test for each situation.     

AE3介导的油茶皂甙在心肌细胞缺氧复氧损伤中的实验研究

目的:阐明油茶皂苷(SQS)所产生心肌保护作用与AE3蛋白的基因表达关系,方法:采用RNA i技术,在心肌细胞水平上建立AE3蛋白低表达、同时建立缺氧/复氧损伤(A/R)模型及SQS预适应模型;通过测定,心肌细胞的博动频律、细胞生存率以及细胞培养液中LDH的变化;同时检测心肌细胞中AE3 mRNA、AE3蛋白的表达变化,结果:SQS预处理能明显提高A/R损伤后细胞存活率,减少LDH的漏出,AE3 mRNA、AE3蛋白表达明显上调,与A/R组相比均有显著性差异(均p<0.01);结论:在心肌细胞中转导入三段有AE3基因序列特异性的dsRNA后,可引起AE3 mRNA及蛋白低表达,同时取消SQS预处理的心肌保护作用.为其进一步的新药开发提供理论与实验依据.     

黄芪总苷对力竭运动大鼠骨骼肌中ATP酶活性的影响

目的：探讨黄芪总苷对力竭运动大鼠骨骼肌中ATP酶活性的影响。方法：对大鼠预防性给予黄芪总苷,观察力竭游泳大鼠骨骼肌ATP酶活性的变化。结果：黄芪总苷组的Na^ ＋K^＋-ATPase和Mg^2＋-AT-Pase的活性明显高于力竭运动组（p〈0.05）,黄芪总苷组的Ca^2＋-ATPase的活力虽也有一定提高,但与力竭运动组无显著性差异（p〉0.05）。结论：黄芪总苷可降低力竭运动对大鼠骨骼肌的损伤,其机制可能与提高ATP酶活性有关。     

我国优秀10m跳台男子运动员下肢肌肉力量特征研究

以现役国家队4名10 m跳台运动员为研究对象,选取相对峰值力矩为评定指标,通过运用MERAC等速肌力测试系统,测试速度分别是60°/s和240°/s,对跳水运动员下肢髋、膝和踝关节主动肌群(伸肌群)的肌力特征进行综合研究,探讨高水平跳水运动员下肢主动肌群的特征.结果显示,下肢关节相对肌力矩水平高是完成高难跳台技术的基础之一;下肢各关节屈伸比值低,伸肌群力量明显大于屈肌群;动员髋关节快速屈伸的肌群的比例相对较高,而膝和踝关节快速屈伸时动员的肌群相对较少;膝关节左、右侧伸肌群力量接近,髋关节左侧大于右侧;随着测试速度的增加,髋关节在下肢总力矩的百分比增加.     

小肌肉群训练对女子皮艇队员力量的影响

对4名女子皮艇运动员增加3个月的小肌肉力量训练,比较和分析实验组与对照组200m水上测试结果,发现实验组队员的速度与桨频的提高幅度均显著高于对照组,结论：小肌肉群训练对提高女子皮艇运动员的速度力量有显著效果。