铅球运动员主要关节等速肌力配布特征

背景：目前,国内外利用等速仪器针对铅球运动主要环节肌肉力量特征方面研究的文献较少。目的：查找铅球运动员不同速度下各主要环节肌力配布特征和存在的不足。方法：利用德国ISOMED2000等速肌力测试系统,对第十一届全运会男子铅球冠军膝关节、髋关节、腰背环节和肩关节进行慢速60 (°)/s和快速180 (°)/s等速测试。结果与结论：①膝关节慢速左右侧屈伸肌比值为25.6%、39.4%,快速屈伸肌比值为28.5%、29.8%,屈肌群肌力较小。②髋关节在快、慢速时,右侧伸肌群分别为左侧的2.11和1.87倍,屈肌群为1.25和1.64倍,右髋非常显著性大于左髋。③腰背环节慢速屈伸肌比值为93.3%,快速测试屈伸肌比值为84.3%。④肩关节自然位屈伸,慢速屈伸肌力右肩分别为左肩的1.27和1.34倍,快速为左肩的1.40和1.92倍。⑤各环节根据人体模型相对质量按膝关节为基准膝、髋、躯干、肩为1∶2.38∶3.30∶0.70。结果表明：①膝关节屈伸肌群绝对肌力、快速屈肌群肌力均较弱,肌群配备不合理。②躯干肌力在右侧最大力量伸肌群、左右侧快速伸肌群非常薄弱,增加腰背肌力伸肌训练,特别是慢速和快速肌肉力量和伸展性训练。③右侧各环节伸肌群薄弱,加强右肩伸肌群的绝对肌肉力量。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

踝关节等速肌力训练对老年脑卒中患者平衡功能的影响

目的　探讨应用等速肌力训练加强踝关节屈伸肌群的肌力,对老年脑卒中患者平衡功能的影响。 方法　选取40例老年脑卒中患者随机分为对照组（n=20）、治疗组（n=20）,对照组接受常规康复治疗,治疗组在对照组基础上,增加针对踝关节背伸与跖屈肌群的等速肌力训练。2组患者治疗前和治疗3周后均进行Berg平衡量表（Berg balance scale, BBS）;“起立-走”计时测试（Timed up and go test, TUGT）;以及ProKin平衡仪的评估,参数包括Y-COP标准差、运动轨迹长度、运动轨迹面积、踝关节背伸与跖屈肌群的等速峰力矩等平衡功能相关指标的测量。 结果　2组患者经过平衡训练后,平衡功能的各项指标均较治疗前有改善(P<0.05）;治疗组患者治疗后平衡功能与对照组比较,各项评估指标均优于对照组(P<0.05）。 结论　踝关节等速肌力训练,可以明显改善老年脑卒中患者踝关节背伸与跖屈肌群的肌力及平衡功能。     

青少年运动员肩关节屈伸肌等速肌力测试与分析

BACKGROUND: The isokinetic muscle strength test system can quantitatively test the shoulder flexor and extensor muscles and objectively analyze the relationship between size and balance of flexor and extensor. Therefore, it could be used for strength training monitoring as well as prediction and rehabilitation of sports injuries. OBJECTIVE: To understand shoulder flexor and extensor strength characteristics of adolescent softball players, and find out shortcomings in the shoulder flexor and extensor strength to provide guidance for adolescent athletes’ strength training and point out possible sports injury risks caused by imbalanced strength. METHODS: ISOMED2000 isokinetic testing system (D&R, Germany) was employed to test the isokinetic strength of shoulder flexor and extensor of 12 adolescent female softball players from Shanghai Sports University, China. RESULTS AND CONCLUSION: With the increase of test speed, the bilateral shoulder flexor and extensor peak torque, the flexor and extensor average power ratio, and the flexor and extensor powers were reduced, but the flexor and extensor average power was on the rise. Under the same test speed, flexor and extensor peak torque, the flexor and extensor peak torque ratio, the flexor and extensor average power, the flexor and extensor average power ratio and the flexor powers of the throwing shoulder were significantly larger than those of the non-throwing shoulder (P < 0.05), while the extensor peak torque and the extensor average power of the throwing and non-throwing shoulders showed no significant differences (P > 0.05). Under the same test speed, bilateral shoulder homonymous flexor strength ratio was larger than that of the extensor, and the extensor power of the throwing shoulder was less than that of the non-throwing shoulder. The ratio of homolateral shoulder flexor and extensor ranged from 70% to 80%. These results indicate that there is a significant difference between the flexor strength of the bilateral shoulders in adolescent softball players, but the bilateral extensor strength is similar. Flexor fast strength and extensor maximum strength of the throwing shoulder are lower. Besides, the isokinetic muscle strength test system can be used to evaluate the flexor and extensor strength in adolescent softball athletes, based on which coaches can give targeted strength training in adolescent softball athletes. 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

青少年男子体操运动员主要关节的等速肌力特征

BACKGROUND: The gymnastic skill training of juveniles tends to be scientific and systematic, such as confirming the strength characteristics of joints and muscles and implementing training program pertinently based on the scientific diagnostic method. OBJECTIVE: To explore the isokinetic muscle strength characteristics of the trunk, hips and knees in juvenile male gymnasts. METHODS: Sixteen juvenile male gymnasts who were active athletes in Liaoning province were enrolled. ISOMED2000 isokinetic muscle strength test system was used to detect the muscle strength, and the test speed of trunk set as 30, 60 and 180 (°)/s, while 60, 180 and 300 (°)/s for the hips and knees. RESULTS AND CONCLUSION: At 30, 60 and 180 (°)/s, the hamstring/quadriceps ratio of trunk were 91.36±1.25, 87.77±3.74 and 78.20±4.70, respectively. At 60, 180 and 300 (°)/s, the hamstring/quadriceps ratio of the left hip was 65.55±4.38, 66.92±3.22 and 68.18±2.82, while that of the right hip were 57.40±4.43, 65.73±1.07 and 64.15±5.55. Additionally, the left flexor strength was significantly higher than that of the right, while the right extensor strength was significantly higher than that of the left at 60 (°)/s (P < 0.05). At 60, 180 and 300 (°)/s, the hamstring/quadriceps ratio was 50.88±4.98, 54.75±4.51 and 58.80±7.93 for the left knee, and 51.55±4.30, 55.20±5.08 and 58.43±5.93 for the right knee. In three test speeds there were no significant differences in flexor and extensor strength between two sides (P > 0.05). These results indicate that the rapid strength of the back especially of the flexor is insufficient markedly, and the basic strength of the extensor is weak. The basic strength of the left flexor in the hip is large, the same as the right extensor; the rapid strength of flexor is weak, and imbalance in the muscle strength between two sides appears. Fortunately, the muscle strength of the knee between two sides achieves balance, but there is still a certain deficiency in the rapid strength of the left flexor and the basic strength of the extensor on both sides. 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

等速肌力测试膝、踝关节及腰背肌力量的评价

背景：等速肌力测试已普遍用来作为运动员肌肉系统的机能状态和运动损伤的治疗效果评定的一种客观指标。 目的：探讨作为足球运动专项肌群的腰背肌、膝关节以及踝关节肌力特征。 方法：运用Cybex-Norm等速肌力测试与训练系统评价足球运动员在不同角速度下的膝、踝关节及腰背肌群屈伸肌峰力矩、相对峰力矩以及耐力水平。 结果与结论：运动员膝、踝关节左右两侧肌力发展较为均衡(< 5%),膝关节伸肌峰力矩和相对峰力矩偏低,屈肌峰力矩和相对峰力矩偏高,左侧膝关节表现尤为突出,不利于比赛时有效地控球、踢球和纵跳等动作的完成;腰背肌群相对峰力矩值相对较弱,容易在运动过程中发生损伤,引起下背痛类疾病;膝、踝关节以及腰背肌群的速度耐力水平均有较大提高空间。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

全身振动训练对老年人下肢功能和慢性疾病影响的研究与进展北大核心

背景:近些年关于全身振动训练的研究在逐年增多,全身振动仪器也开始逐渐流行,全身振动训练的价值正在逐渐被挖掘,特别是不便于参加常规锻炼的体质弱势人群被认为能够在全身振动训练中受益,其中老年人占了较大比重。目的:阐述全身振动训练在下肢功能和慢性疾病两个方面对老年人产生的影响并对相应机制进行探讨,为其他全身振动训练研究提供参考。方法:由第一作者以"whole body vibration"为主题词在Web of Science核心合集数据库和PubMed数据库检索1998年至2015年的全身振动训练文献,然后以"older adult"、"elderly"、"seniors"和"aging"为关键词进行筛选;中文数据库选择中国知网(CNKI),以"振动训练"、"老年"、"高龄"为主题词进行检索,其中振动之于肺部疾病的研究除外。文献筛选时以60岁为标准来界定老年人群,下肢功能方面选择与老年人跌倒相关且易在全身振振动训练中产生效果的"神经肌肉功能"、"平衡功能"和"步行功能",慢性疾病方面选择与全身振动训练作用机制联系紧密的神经肌肉系统类和心血管系统类疾病,包括脑卒中、Ⅱ型糖尿病、高血压和帕金森病。结果与结论:老年人在全身振动训练中的下肢肌力增强效果显著,平衡和步行功能都得到了不同程度的提高。在慢性疾病(脑卒中、2型糖尿病、高血压及帕金森病)方面,全身振动训练的效用主要表现在神经-肌肉系统功能上,如肌力增强、肌肉僵硬和震颤程度减轻等,全身振动训练对老年人慢性疾病的部分指标也存在着改善效应。全身振动训练是一种安全、有效的训练方法,在肌肉力量、平衡和步行功能方面有提升需求的老年人可以使用此训练方法。老年人在选择全身振动训练时要衡量其投入-产出比,不能因其耽误常规治疗,关于全身振动训练未来还需要大量深度研究来明确已有效益及发现更多适用领域。     

闭眼单脚站立方法在体质测试中的应用

背景：闭眼单脚站立是反应肌力与平衡能力的测试方法,在中国被作为评价成年人和老年人平衡能力的重要素质指标, 以往有大量的测试工作,但深入的研究报道较少。 目的：总结闭眼单脚站立方法的国内外研究现状,分析闭眼单脚站立在体质测试中存在的问题,并展望研究方向。 方法：通过计算机检索CNKI 和Elsevier数据库中相关文献,关键词为“闭眼单脚站立,平衡能力,体质测试”。对资料进行初审,选取符合研究要求的文献。 结果与结论：中国男性闭眼单脚站立评分标准高于女性;测试中出现部分老年人站立时间很短,很难评定其平衡能力;老年人平衡能力明显低于中、青年人,成年人与老年人采用相同的测试方法是否具有科学性;在简单平衡能力测试方法中,闭眼单脚站立的各项指标相关系数较低。鉴于以上原因,闭眼单脚站立作为国民体质平衡能力评价的测试方法尚待进一步研究。     

含裂纹缺损关节软骨的单轴准静态拉伸性能

背景:关节软骨一旦出现裂纹缺损其力学性能会发生改变,而先前研究中针对受损关节软骨的探究多集中在压缩,对于拉伸性能的研究较少。目的:预先在软骨层试样上制造裂纹缺损,测试其单轴准静态拉伸性能。方法:选取新鲜成年猪膝关节的关节软骨,制备含裂纹缺损的软骨试样,在不同应力率下(0.001,0.01,和0.1 MPa/s)测试其拉伸性能,在不同恒定应力下(1,2,3 MPa)测试其蠕变性能。结果与结论:①不同应力速率下的拉伸实验中,随着应力速率的增加,达到相同应变所需的应力逐渐增大,且试件的杨氏模量随应力率的增加而增加;②不同应力速率下含裂纹缺损关节软骨的拉伸应力-应变曲线不重合,说明含裂纹缺损关节软骨的拉伸性能具有率相关性;③不同恒定拉应力水平下的蠕变实验中,蠕变应变随着拉应力水平的提高而增大,蠕变柔量随拉应力水平的提高而降低,并且随着蠕变时间的推移蠕变应变先快速增加后缓慢增加;④结果表明,不同应力率和不同恒定应力对含裂纹缺损关节软骨的拉伸力学性能影响较大,该实验结果可为缺损关节软骨的修复提供力学参考。     

基于静态姿势图的人体平衡功能检测与评估

为有效检测和评估老年人及残疾人的平衡功能障碍,提出一种平衡功能检测与评估方法.首先选取睁眼及闭眼模式下的重心轨迹长度、单位面积轨迹长度、峭度、左右重心分布比及前后重心分布比共10个指标来定量检测平衡功能,然后运用主成分分析法对所选评价指标进行融合,最后根据主成分因子的方差贡献率确定主成分因子的权值,进而得出综合评价值,以此帮助受试者完成平衡功能评估.采用自行研制的平衡功能检测与评估系统,在2周内对30例平衡功能障碍患者(病例组)和30例性别、年龄、身高及体重与病例组相匹配的健康人(对照组)进行2次平衡功能检测与评估,对照组综合评价值的统计值为4.067±0.540(n=30,mean ± SD),病例组综合评价值的统计值为2.054±0.685,两组相比具有统计学显著差异.实验表明,该平衡功能检测与评估方法合理,具有应用价值.     

核心力量训练干预老年慢性下腰疼的研究与进展

BACKGROUND: Numerous studies have confirmed the effectiveness of core strength training, most of which focus on the adult rather than the elderly.  OBJECTIVE: To review the relevant literatures targeting the elderly with low back pain and to explore the mechanism of core strength training in the treatment of elderly low back pain as well as different training methods and precautions, in order to provide theoretical basis for treatment of elderly patients with chronic low back pain. METHODS: Studies on the application of core strength training in the elderly with low back pain were retrospectively reviewed using bibliometrics method. The keywords were “chronic low back pain, core strength training, elderly person” in English and Chinese, respectively. RESULTS AND CONCLUSION: A large number of scholars have focused on the non-pathological therapy for elderly patients with chronic lower back pain. Core strength training for treatment of low back pain is characterized as a simple operation, low cost, significant effectiveness and few side effects, which is basically applicable in different groups. Combination of two or more exercise therapies can enhance the core strength training effect. In addition, correct health concept education, psychological and behavioral interventions are necessary to o eliminate the fear of pain and improve patient compliance, thereby increasing the effectiveness of exercise therapy. During the core strength training, we also should pay attention to distinguish the severity of diseases, degree of urgency, stage of disease, age, and individual physical differences, and take targeted exercises.        

Combined effect of heat stress, dehydration and exercise on neuromuscular function in humans

This study examined the combined effect of exercise induced hyperthermia and dehydration on neuromuscular function in human subjects. Six trained male runners ran for 40 min on a treadmill at 65% of their maximal aerobic velocity while wearing a tracksuit covered with an impermeable jacket and pants to impair the evaporation of sweat. These stressful experimental running conditions led the runners to a physiological status close to exhaustion. On average, the 40 min run ended at a heart rate of 196 (SD 8) beats · min⁻¹, a tympanic temperature of 40 (SD 0.3) °C and with a loss of body mass of 2 (SD 0.5)%. Pre- and post-running strength tests included measurements of maximal knee extension and flexion torques in both isometric and isokinetic (at 60 and 240° · s⁻¹) conditions. A 20 s endurance test at 240° · s⁻¹ was also performed. Surface electromyographic (EMG) activity was recorded from six knee extensor and flexor muscles during the entire protocol. The treadmill run led to clear decrements in maximal extension torque and EMG activity both in isometric and at the slowest isokinetic velocity (60° · s⁻¹). However, no differences in these parameters were observed at 240° · s⁻¹. Furthermore, the EMG patterns of the major knee extensor and flexor muscles remained remarkably stable during the treadmill run. These results demonstrate that the exercise-induced hyperthermia and dehydration in the present experiments had only minor effects on the neuromuscular performance. However, it is also suggested that high internal body temperature per se could limit the production of high force levels. Accepted: 26 September 2000     

The effect of vertical whole-body vibration on lower limb muscle activation in elderly adults: Influence of vibration frequency,amplitude and exercise

ObjectiveThis study aimed to investigate how whole-body vibration (WBV) and exercise and their interactions influenced leg muscle activity in elderly adults.Study designAn experimental study with repeated measures design that involved a group of ambulatory, community-dwelling elderly adults (n = 30; 23 women; mean age = 61.4 ± 5.3 years).Main outcome measuresMuscle activity of the vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA), and gastrocnemius (GS) was measured by surface electromyography (EMG), while participants were performing seven different exercises during 4 WBV conditions (condition 1: frequency = 30 Hz, amplitude = 0.6 mm, intensity = 2.25 units of Earth’s gravity (g); condition 2: 30 Hz, 0.9 mm, 3.40 g; condition 3: 40 Hz, 0.6 mm, 3.65 g; condition 4: 40 Hz, 0.9 mm, 5.50 g) and a no-WBV condition in a single experimental session.ResultsSignificantly greater muscle activity was recorded in VL (3%–148%), BF (16%–202%), and GS (19% –164%) when WBV was added to the exercises, compared with the same exercises without WBV (p ≤ 0.015). The effect of vibration intensity on EMG amplitude was exercise-dependent in VL (p = 0.002), and this effect was marginally significant in GS (p = 0.052). The EMG activity induced by the four WBV intensities was largely similar, and was the most pronounced during static erect standing and static single-leg standing.ConclusionsThe EMG amplitude of majority of leg muscles tested was significantly greater during WBV exposure compared with the no-WBV condition. Low-intensity WBV can induce muscle activity as effectively as higher-intensity protocols, and may be the preferred choice for frail elderly adults.     

胸段脊髓损伤患者应用截瘫步行矫形器对下肢康复的影响

背景：胸段脊髓损伤常导致双下肢截瘫,截瘫步行矫形器能帮助截瘫患者改善下肢功能障碍,提高日常生活活动能力,重获站立和行走能力。 目的：探讨截瘫步行矫形器对胸段脊髓损伤患者下肢肌肉痉挛及功能恢复的影响。 方法：将20例胸段脊髓(T5-12)损伤患者根据损伤平面按美国脊髓损伤协会(American Spinal Injury Association,ASIA)标准分为完全损伤组和不完全损伤组,各10例,均装配截瘫步行矫形器。分别于装配前进行残余肌力训练、坐位平衡训练、转移训练;装配后平行杆内站立训练、平衡及转移训练;室内、户外助行器、肘拐步行训练。 结果与结论：与治疗前相比,胸髓完全性损伤患者装配截瘫步行器治疗12周后ASIA评分增加,感觉无明显变化,痉挛随病程的延长而加重;不完全性损伤患者治疗12周后ASIA评分增加,感觉明显改善,痉挛随病程的延长无改变;两组患者日常生活活动能力(改良Barthel指数、功能独立性评测)有显著改善。与治疗2周时相比,治疗12周时2组患者10 m行走时间显著减少,6 min步行距离延长。说明胸段脊髓损伤患者装配截瘫步行器,能显著改善患者的运动功能、日常生活活动能力和步行能力,对肌痉挛控制也有一定的影响。 中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

Lower limb force production and bilateral force asymmetries are based on sense of effort

Previous research suggests that individuals use a sense of effort, more than proprioceptive feedback, to gauge force production in their upper limbs. We have adopted an isometric force matching task to determine if force asymmetry between lower limbs during bilateral force production results from a neural mechanism related to sense of effort. We hypothesized that subjects attempting to produce equal lower limb forces would generate equal percentages of their bilateral maximum voluntary strength rather than equal absolute limb forces. Ten subjects performed isometric lower limb extensions on an exercise machine. Subjects attempted to match forces in their lower limbs at three different submaximal levels (20, 40, and 60% of their weaker limb peak force during bilateral maximum voluntary contraction). Subjects received visual feedback of only the target and stronger limb force. Results showed that subjects consistently produced less force in their weaker limb during all force matching levels when normalized to their unilateral maximum voluntary contraction force (ANOVAs 20% P = 0.0473, 40% P = 0.0012, 60% P = 0.0007). As predicted by our hypothesis, normalizing force magnitudes by bilateral maximum voluntary contraction forces revealed no significant differences between limbs at all force levels (ANOVA P = 0.8490). Regardless of whether humans produce maximal or submaximal forces, limb force asymmetry appears to be related to neural factors rather than differences in mechanical capabilities between the limbs. Our findings have implications for bilateral asymmetries during movement in healthy and neurologically impaired populations.     

Changes in strength and cross sectional area of the elbow flexors as a result of isometric strength training

Summary Changes in strength and size of the elbow flexor muscles have been compared during six weeks of isometric strength training in six male and six female subjects. Isometric training of one arm resulted in a significant increase in isometric force (14.5±5.1%, mean±SD,n = 12). No differences were seen in the response of male and female subjects. The extent of the change was similar to that reported for training studies of other muscles, thus refuting the suggestion that the elbow flexors may be especially amenable to training. Biceps and brachialis cross-sectional area (CSA) was measured from mid-upper arm X-ray computerized tomography before and after training. Muscles increased in area (5.4±3.8%) but this was smaller than, and not correlated with, the increase in strength. The main change in the first six weeks of strength training was therefore an increase in the force generated per unit cross-sectional area of muscle. The arrangement of fibres in the biceps is nearly parallel to the action of the muscle and it is argued that the increase in force per unit cross-sectional area is unlikely to be due to changes in the pennation of the muscle fibres as has been suggested for other muscles.     

Effect of strength training on the relationship between magnetic resonance relaxation time and muscle fibre composition

Summary The effect of muscle hypertrophy on the relationship between magnetic resonance (MR) relaxation time and muscle fibre composition was investigated. Relaxation time and muscle fibre composition were measured in five subjects before and after a 20-week period of strength training. Muscle fibre composition in all subjects exhibited a significant shift to a predominance of fast-twitch (FT) fibres as a result of 20-week strength training (% area FT fibres: mean values from 49.8%, SD 17.9% to 57%, SD 5.6%; P<0.05). Longitudinal relaxation time (T₁) and transverse relaxation time (T₂) were prolonged significantly after strength training (T₁ mean values from 334.9 ms, SD 13.6 to 359.0 ms, SD 9.0, P<0.001; T₂ from 27.5 ms, SD 0.9 to 30.8 ms, SD 2.3, P<0.05). A constant relationship was observed in changes caused by strength training in muscle fibre composition (% area FT) and relaxation time, with a high correlation obtained between both parameters. These results indicate that MR relaxation time can be used for non-invasive estimation of muscle fibre composition.     

Neuromuscular adaptation during prolonged strength training, detraining and re-strength-training in middle-aged and elderly people

Effects of a 24-week strength training performed twice weekly (24 ST) (combined with explosive exercises) followed by either a 3-week detraining (3 DT) and a 21-week re-strength-training (21 RST) (experiment A) or by a 24-week detraining (24 DT) (experiment B) on neural activation of the agonist and antagonist leg extensors, muscle cross-sectional area (CSA) of the quadriceps femoris, maximal isometric and one repetition maximum (1-RM) strength and jumping (J) and walking (W) performances were examined. A group of middle-aged (M, 37–44 years, n=12) and elderly (E, 62–77, n=10) and another group of M (35–45, n=7) and E (63–78, n=7) served as subjects. In experiment A, the 1-RM increased substantially during 24 ST in M (27%, P < 0.001) and E (29%, P < 0.001) and in experiment B in M (29%, P < 0.001) and E (23%, P < 0.01). During 21 RST the 1-RM was increased by 5% at week 48 (P < 0.01) in M and 3% at week 41 in E (n.s., but P < 0.05 at week 34). In experiment A the integrated electromyogram (IEMG) of the vastus muscles in the 1-RM increased during 24 ST in both M (P < 0.05) and E (P < 0.001) and during 21 RST in M for the right (P < 0.05) and in E for both legs (P < 0.05). The biceps femoris co-activation during the 1-RM leg extension decreased during the first 8-week training in M (from 29 ± 5% to 25 ± 3%, n.s.) and especially in E (from 41 ± 11% to 32 ± 9%, P < 0.05). The CSA increased by 7% in M (P < 0.05) and by 7% in E (P < 0.001), and by 7% (n.s.) in M and by 3% in E (n.s.) during 24 ST periods. Increases of 18% (P < 0.001) and 12% (P < 0.05) in M and 22% (P < 0.001) and 26% (P < 0.05) in E occurred in J. W speed increased (P < 0.05) in both age groups. The only decrease during 3 DT was in maximal isometric force in M by 6% (P < 0.05) and by 4% (n.s.) in E. During 24 DT the CSA decreased in both age groups (P < 0.01), the 1-RM decreased by 6% (P < 0.05) in M and by 4% (P < 0.05) in E and isometric force by 12% (P < 0.001) in M and by 9% (P < 0.05) in E, respectively, while J and W remained unaltered. The strength gains were accompanied by increased maximal voluntary neural activation of the agonists in both age groups with reduced antagonist co-activation in the elderly during the initial training phases. Neural adaptation seemed to play a greater role than muscle hypertrophy. Short-term detraining led to only minor changes, while prolonged detraining resulted in muscle atrophy and decreased voluntary strength, but explosive jumping and walking actions in both age groups appeared to remain elevated for quite a long time by compensatory types of physical activities when performed on a regular basis. Accepted: 2 May 2000     

Effects of age and regular exercise on muscle strength and endurance

Summary Twenty male and 20 female non-professional tennis players were classified into two different age groups (n=10 per group): young active men (30.4±3.3 years), young active women (27.5±4.3 years), elderly active men (64.4±3.7 years), and elderly active women (65.3±4.5 years). These individuals were matched (n = 10 per group) according to sex, age, height and mass to sedentary individuals of the same socio-economical background: young sedentary men (29.2±3.4 years), young sedentary women (25.6±4.4 years), elderly sedentary men (65.2 ± 3.2 years) and elderly sedentary women (65.6±4.4 years). An isokinetic dynamometer was used to measure the strength of the knee extensors and flexors (two separate occasions) and the endurance of the extensors. Vastus lateralis electromyogram (EMG) was measured concomitantly. Significant sex, age and exercise effects (P<0.001) were observed for peak torque of both muscle groups. The effect of age on extensor strength was more pronounced at high speeds where men were also able to generate larger relative torques than women.No age or sex effects were noted for muscle endurance. However, muscles of active individuals demonstrated a greater resistance to fatigue than those of sedentary individuals. In conclusion, men were found to be stronger than women, age was associated with a decrease in muscle strength, but not of muscle endurance, and tennis players were stronger and had muscles that were more resistant to fatigue than their sedentary pairs in both age groups. Although the results of this study cannot be generalized to other types of sports activities, they do give credence to the health benefits of moderate exercise in the maintenance of muscle function with age.     

Combined lower body endurance and upper body resistance training improves performance and health parameters in healthy active elderly

We investigated the effects of combined lower body (LB) endurance and upper body (UB) resistance training on endurance, strength, blood lipid profile and body composition in active older men. Ten healthy still active men (73 ± 4 years, peak: 36 (31–41) ml min⁻¹ kg⁻¹) were tested before and after 14 weeks of combined training (3 times week⁻¹). Training consisted of 3 × 12 min of high intensity interval training on a bicycle for endurance interspersed by 3 × 12 min of UB resistance exercises. peak during leg cycling and arm cranking, isokinetic torque of knee extensor and shoulder abductor and the cross-sectional area (CSA) of several muscles from UB and LB were measured. Sagittal abdominal diameter (SAD) and abdominal fat area were measured on MRI scans. Total body composition was assessed by hydrostatic weighing (HW) and dual-energy X-ray absorptiometry (DEXA). Blood lipid profile was assessed before and after training. By the end of the training period, peak (l min⁻¹) increased significantly by 9 and 16% in leg cycling and arm cranking tests, respectively. Maximal isokinetic torque increased both for the knee extensor and shoulder abductor muscle groups. CSA increased significantly in deltoid muscle. Percentage of body fat decreased by 1.3% (P < 0.05) and abdominal fat and SAD decreased by 12 and 6%, respectively (P < 0.01). There was also a significant decrease in total cholesterol and low-density lipoprotein. Thus, combined LB endurance and UB resistance training can improve endurance, strength, body composition and blood lipid profile even in healthy active elderly.