The acute effect of lower-limb warm-up on muscle performance

It has been purported that the mechanism for muscular improvement after a gluteal warm-up protocol is likely to occur from neural activation. However, little is known about whether changes in muscular performance are due to changes in muscle activity. Therefore, the aim of this study was to determine whether a lower-limb warm-up that targets the gluteal muscle group would improve countermovement jump and short-distance sprinting through increased muscle activity. Ten semi-professional rugby union players (age 25.4 ± 2.9 yr; height 1.83 ± 6.7 m; body mass 96.8 ± 10.6 kg) with at least three years of resistance training experience volunteered for the study. In a cross-over design, participants performed countermovement jumps and 5 m sprints before and after a gluteal warm-up and a 10 min rest (control). Electromyography was used to measure muscle activity of the gluteus maximus and biceps femoris. Countermovement jump height significantly improved (7.9%, p < 0.05) after the lower-limb warm-up protocol compared with the control (3.2%). There was a significant (p < 0.05) improvement in sprint times over 2.5 m and 5 m regardless of the condition. There was no significant change in the muscle activity in any of the conditions. The results indicate that a lower-limb warm-up can acutely enhance countermovement jump performance compared to a control.     

Procedimiento de Nishida asociado a toxina botulínica en parálisis completa del sexto par craneal bilateral de larga evolución

In severe cases of abducens or sixth cranial nerve palsy, transpositions of the superior rectus and inferior rectus into the paralytic lateral rectus have been demonstrated to be useful. Numerous techniques have been described over time to carry out these transpositions, such as the Hummelsheim, O’Connor, Jensen, Foster, or Nishida technique. The first 4 techniques mentioned above have an increased risk of anterior segment ischaemia.The case is presented of a long-standing bilateral sixth cranial nerve palsy secondary to a severe cranial injury. Given the risk of ischaemia of the anterior segment, the Nishida technique was chosen in order to reduce the risk of suffering from this complication. This is combined with botulinum toxin in both middle rectus to try to resolve the muscle contracture associated with the long evolution of the case, obtaining good results at 6, and 12 months after the surgical procedure.     

229例婴儿超声波髋关节检查股骨头骨化中心出现的相关因素分析

目的:探讨229例婴儿超声波髋关节检查婴儿股骨头骨化中心出现早晚的相关因素分析.方法:对上海市长宁区妇幼保健院2013年10月～2014年11月出生的229例婴儿超声波髋关节B超检查,其中94例产后体检髋关节即出现股骨头骨化中心及135例产后体检髋关节未出现骨化中心的婴儿设立对照组进行相关因素分析.结果:超声波髋关节检查中婴儿性别与髋关节股骨头骨化中心出现早晚差异有统计学意义(P＜0.01),母孕期及婴儿期补钙情况与髋关节内骨化中心出现的早晚差异无统计学意义(P＞0.05),婴儿喂养方式与髋关节股骨头骨化中心出现早晚的差异无统计学意义(P＞0.05),母亲产后体检血25羟维生素D3、血微量元素血钙值、骨密度值与髋关节内骨化中心出现早晚的差异无统计学意义(P＞0.05).结论:婴儿髋关节股骨头骨化中心在4～6月龄中胎龄越大的婴儿出现越早,女婴髋关节股骨头骨化中心比男婴出现的早.补钙及母亲缺钙情况不能反映婴儿髋关节股骨头骨化中心出现的早与晚.     

Cellular adaptation contributes to calorie restriction-induced preservation of skeletal muscle in aged rhesus monkeys

We have previously shown that a 30% reduced calorie intake diet delayed the onset of muscle mass loss in adult monkeys between ~16 and ~22 years of age and prevented multiple cellular phenotypes of aging. In the present study we show the impact of long term (~17 years) calorie restriction (CR) on muscle aging in very old monkeys (27-33 yrs) compared to age-matched Control monkeys fed ad libitum, and describe these data in the context of the whole longitudinal study. Muscle mass was preserved in very old calorie restricted (CR) monkeys compared to age-matched Controls. Immunohistochemical analysis revealed an age-associated increase in the proportion of Type I fibers in the VL from Control animals that was prevented with CR. The cross sectional area (CSA) of Type II fibers was reduced in old CR animals compared to earlier time points (16-22 years of age); however, the total loss in CSA was only 15% in CR animals compared to 36% in old Controls at ~27 years of age. Atrophy was not detected in Type I fibers from either group. Notably, Type I fiber CSA was ~1.6 fold greater in VL from CR animals compared to Control animals at ~27 years of age. The frequency of VL muscle fibers with defects in mitochondrial electron transport system enzymes (ETS(ab)), the absence of cytochrome c oxidase and hyper-reactive succinate dehydrogenase, were identical between Control and CR. We describe changes in ETS(ab) fiber CSA and determined that CR fibers respond differently to the challenge of mitochondrial deficiency. Fiber counts of intact rectus femoris muscles revealed that muscle fiber density was preserved in old CR animals. We suggest that muscle fibers from CR animals are better poised to endure and adapt to changes in muscle mass than those of Control animals.     

A modified direct lateral approach for neck-preserving total hip arthroplasty: tips and technical notes

Tissue-sparing surgery for hip replacement aims to minimize muscle damage and conserve the femoral neck through the use of mini-prostheses. We propose a modification of the classical direct lateral access procedure that preserves the gluteus medius. Further advantages during the surgical phase include limited blood loss, visualization of the entire acetabulum, and sparing of the transverse ligament. Precise implantation is facilitated and normal biomechanics are preserved. The gluteus medius is divided longitudinally between the anterior third and posterior two-thirds to provide access to the gluteus minimus, which is detached from the femoral insertion together with a small portion of the vastus lateralis, forming a flap that exposes the underlying articular capsule. When the femoral head is revealed, a decision is made to either continue with its dislocation directly or to resect it and remove it separately to avoid damaging the gluteus medius during dislocation. Upon removal of the femoral head, with the limb flexed and slightly over-rotated, the acetabulum is completely visible. Limb length is maintained through the use of reference stitches on the gluteus minimus tendon and the proximal insertion of the vastus lateralis. In keeping with the minimally invasive philosophy, only pathological tissue is removed (marginal osteophytes, geodes, joint capsule, cartilage to the point of bleeding and pulvinar). We have performed more than 2,000 implants with this procedure since 1990. Advantages and potential critical points are discussed.     

Muscle architecture adaptations to knee extensor eccentric training: Rectus femoris vs. vastus lateralis

Introduction: Changes in muscle architecture induced by eccentric knee extensor training remain unclear, as well the adaptive responses of synergistic knee extensor muscles with different geometrical designs. Methods: Ultrasonography images were taken from rectus femoris (RF) and vastus lateralis (VL) of 20 male volunteers before and after a non‐training control period of 4 weeks, and additional evaluations were performed after 4, 8, and 12 weeks of isokinetic eccentric training. Results: RF and VL had significant changes in muscle architecture within the first 4 training weeks, and the adaptive response throughout the intervention was similar. Muscle thickness increased by around 7–10%, fascicle length increased 17–19%, and pennation angle was unchanged. Conclusions: Increased muscle thickness due to eccentric training was related to increased fascicle length and not to pennation angle changes. Although RF and VL have a different fascicular geometry, they had similar morphological adaptations to eccentric training. Muscle Nerve 48 : 498–506, 2013