The relationship between muscle cross-sectional area and strength in various isokinetic movements among soccer players

Abstract

The aim of the present study was to examine the relationships between muscle cross-sectional area (CSA) and muscular strength in terms of knee extension and flexion, hip extension and flexion, and hip abduction and adduction among well-trained soccer players. Fourteen university soccer players participated in the study, who had previously been divided into two groups based on ability (Group A: above-average ability; Group B: average ability). Maximal isokinetic and concentric muscular strength was measured in knee extension/flexion, hip extension/flexion and hip abduction/adduction using an isokinetic dynamometer at 1.57 and 4.19 rad·s^?1 (3.14 rad·s^?1) in both the dominant and non-dominant leg. The CSAs of the thigh, gluteus muscles and iliopsoas muscles were calculated based on magnetic resonance imaging. There was no significant difference between the two groups in muscle CSA and isokinetic strength. Although there were some statistically significant differences between the dominant and non-dominant leg in terms of CSA and strength (P<0.05–0.01), these were small and negligible. Apart from a non-significant relationship between the CSAs of the adductor muscles and hip adductor strength (r<0.26, n.s.), the CSA of the other muscle groups correlated with maximal isokinetic strength (r=0.38–0.64, P<0.05). These results suggest that no difference in muscle characteristics (in terms of muscle CSA and strength) was apparent among well-trained soccer players, even between the dominant and non-dominant leg. There is also a case that the anatomical function of a single (or group of) muscle(s) may not be reflected by the strength—CSA relationship depending on the movements (such as hip adduction-adductor muscle CSA). Thus, further studies are required to develop methods to assess neuromuscular function in relation to muscle morphology among soccer players.     

优秀水球运动员膝关节肌群等速向心收缩力量特征研究

利用等速测试及康复系统对优秀水球运动员膝关节肌群进行等速向心收缩测试与分析,结果发现,峰力矩可作为评价水球运动员膝关节肌力大小的一个敏感指标,峰力矩值越大,肌肉做功能力越强,做功效率越高。水球运动员膝关节慢速肌力与快速肌力呈非常显著相关,其左右膝关节肌力相当平衡,快速屈伸肌比率大于慢速屈伸肌,屈肌的慢速力量较弱。     

中学生动态等速肌力自然发育的年龄规律与性别特点

探索肌肉力量自然发育过程中的年龄相关性和性别特点。运用Kineteeh等速肌力测试系统，对240名13～18岁普通中学生进行动态等速肌力测试评定。结果表明13～18岁男生，上、下肢屈伸肌的最大肌力和输出功率持续增长；从14岁开始，出现快速增长，各年龄段男生的肌力均大于女生，14岁为男生动态等速肌力快速生长的敏感期。同期女生的最大肌力和输出功率也持续增长，但增长的速度明显小于男生，16岁后增长缓慢，16岁开始男女生之间的差距拉大。     

力量训练、有氧运动对体能类男性运动员BMI、骨骼肌含量、体脂百分比的影响

选取20名体能类男性运动员,分为力量训练组和有氧训练组进行为期8周的对照实验。实验发现不同运动对人体成分的改变效果不同,力量训练可以促进骨骼肌的增长,有氧训练可以起到降低体重、减小体脂、抑制骨骼肌增长的作用。     

老年男性衰老过程中骨密度与平衡能力及握力的关系

通过测量华东地区部分老年男性左脚跟骨骨密度 (BMD)、平衡能力和握力 ,探讨衰老过程中老年男性跟骨BMD、平衡能力和握力的变化以及跟骨BMD与平衡能力及握力的关系。结果显示 ,随着年龄增长 ,老年男性跟骨BMD变化不明显 ,老年男性平衡能力和握力呈现显著下降趋势。 65～ 69岁组和≥ 75岁组老年男性BMD与平衡能力呈显著正相关 (P <0 .0 5和P <0 .0 1)。 65～ 69岁组和 70～ 74岁组老年男性BMD与握力呈显著正相关 (P <0 .0 5)。结果提示 ,老年男性跟骨BMD与平衡能力及握力存在内在的联系     

The improvement in walking speed induced by resistance training is associated with increased muscular strength but not skeletal muscle mass in older women

Objective: The purpose of the present study was to analyze whether improvements in fast walking speed induced by resistance training (RT) are associated with changes in body composition, muscle quality, and muscular strength in older women. Methods: Twenty-three healthy older women (69.6?±?6.4 years, 64.95?±?12.9?kg, 1.55?±?0.07?m, 27.06?±?4.6?kg/m²) performed a RT program for 8 weeks consisting of 8 exercises for the whole body, 3 sets of 10–15 repetitions maximum, 3 times a week. Anthropometric, body composition (fat-free mass [FFM], skeletal muscle mass [SMM], legs lean soft tissue [LLST], fat mass), knee extension muscular strength (KE1RM), muscle quality index (MQI [KE1RM/LLST]), and 10-meter walking test (10-MWT) were performed before and after the intervention. Results: Significant (P?<?.05) changes were observed from pre- to post-training for FFM (+1.6%), MQI (+7.2%), SMM (+2.4%), LLST (+1.8%), KE1RM (+8.6%), fat mass (?1.4%), and time to perform 10-MWT (?3.7%). The percentage change in 10-MWT was significantly associated with percentage change in MQI (r?=??0.46, P?=?.04) and KE1RM (r?=??0.45, P?=?.04), however not associated percentage of changes in SMM (r?=?0.01, P?=?.97), LLST (r?=??0.22, P?=?.33), and body fat (r?=?0.10, P?=?.66). Conclusion: We conclude that the improvement in the 10-MWT after an 8-week RT program is associated with increases in lower limb muscular strength and muscle quality, but not with muscle mass or body fat changes in older women.     

超重肥胖老年女性下肢肌力及平衡能力的运动干预实验研究

目的：针对超重肥胖老年人进行循环训练运动干预设计,探讨循环训练对超重肥胖老年人下肢肌力及平衡能力的影响。方法：以34名老年女性为受试者,分为超重组和对照组,均坚持12周循环训练干预,比较干预前后两组受试者双侧下肢膝踝屈伸等速肌力、静动态平衡能力、计时"起立-行走"时间和Berg平衡量表得分情况。结果：运动干预12周后,两组下肢膝踝屈伸肌标准化峰值力矩、屈伸肌肌力比值和双侧肌力比值、静态与动态平衡能力、Berg平衡量表得分及计时"起立-行走"时间均有显著提高;且超重组的右膝伸肌标准化峰值力矩的提高程度明显高于对照组。结论：循环训练可以显著提高老年人的下肢肌力和平衡能力,且对提高超重肥胖老年人下肢伸肌肌力有更明显的改善效果,是预防老年人跌倒的有效运动方法。     

Effect of resistance training with different frequencies and subsequent detraining on muscle mass and appendicular lean soft tissue,IGF-1, and testosterone in older women

Objective: To analyse the effect of resistance training (RT) frequency on muscle mass, appendicular lean soft tissue, insulin-like growth factor 1 (IGF-1), testosterone, and their changes with detraining in older women. Methods: Forty-five physically independent older women (≥ 60?years) were randomly assigned to perform RT either two (G2X, n = 21) or three times/week (G3X, n = 24), during 12?weeks (8 exercises, 1 set of 10–15 repetition maximum). Muscle mass and appendicular lean soft tissue, IGF-1, testosterone, and dietary intake were measured at pre-training, post-training, and after detraining (12?weeks). Results: Muscle mass and appendicular lean soft tissue significantly increased post-training (G2X?=?+5.5% and G3X?=?+5.8%, P?P?P?Conclusion: We conclude that lower RT frequency is as effective as higher frequency to improve muscle mass and appendicular lean soft tissue, and to maintain testosterone and IGF-1. Additionally, detraining may reduce testosterone regardless of RT frequency. These results are specifically for community-dwelling older women and may not be generalized to other populations.     

Identifying the optimal body shape and composition associated with strength outcomes in children and adolescent according to place of residence: An allometric approach

The purpose of the study was to identify the optimal body shape and composition associated with physical fitness levels of children living in urban and rural areas of Italy. A total of 7102 children (11–14 years) were assessed for weight, height, percentage body fat (FM%), sit-and-reach flexibility (SAR), standing broad jump (SBJ) and sit-ups (SUP). A multiplicative allometric model, Y = a · mass^k1 · height^k2 ·ε, was used to predict the physical outcome variables Y = SBJ and SUP. The model was expanded to incorporate FM% and SAR as follows Y = a · mass^k1 · height^k2 · FM%^k3 · exp(b· FM% + c· SAR) ·ε. Note that FM% was incorporated as a “gamma function” that allows an initial growth, and subsequent decline in Y as FM% increases in size. Although having an ectomorph body shape appears advantageous, being too thin appears detrimental to the strength outcomes. Being flexible would also benefit physical fitness levels. Finally, our results indicate that ursban children aged 11–14 have superior strength outcomes compared with rural children, having controlled for differences in body shape and composition, a finding that may be associated with rural environments having fewer exercise facilities compared with urban conurbations.