UNIVERSIDADE FEDERAL DO RIO GRANDE DO SUL

Aging with quality of life is the biggest challenge for the elderly. Quality of life and independence maintenance are directly related to functionality, which depends on the musculoskeletal system structure and function. Understanding the relationship between muscular parameters and functionality in the elderly allows designing appropriate training programs to prolong this population’s functional independence. In this sense, studies show that the strength training lead to muscle structure and function and functionality gains. Functional tasks are performed utilizing different types of muscle contraction. However, there is no a consensus in the literature considering the relationship between muscle parameters and functionality in the elderly, nor considering the effects of strength trainings utilizing different contraction types on muscle’s structure and function, and on functionality. Thus, the present study had as objectives (1) to identify which lower limbs structural and muscular function parameters present better relation and can explain performance in functional tasks, (2) systematically review the literature about the effects of trainings with different contraction types for older subjects, and (3) to investigate the effects of concentric strength training versus concentric-eccentric training for knee flexors and extensors muscles on parameters of muscle structure and function and functionality in the elderly. To achieve these objectives, this thesis was divided into four chapters. In Chapter 1, the relationship between structural parameters and lower limb muscle function (muscular architecture, echo intensity and isometric strength) and functional parameters (Timed Up and Go and sit-to-stand tests, gait with and without obstacles at the preferred and maximum speed) was verified. In Chapter 2, the relationship between knee flexors and extensors structural parameters and muscle function (isometric, concentric and eccentric torque, power, rate of force production, echo intensity and muscular architecture) and functionality (sit-to-stand, Timed Up and Go, balance, walking speed, six-minute walk test, stair ascent and descent, and vertical jump) was investigated, considering, in addition to the parameters investigated in the Chapter 1, parameters of dynamic strength. The main findings demonstrate that the vastus lateralis and tibialis anterior muscles structure, and the knee extensor concentric torque were the parameters with better relation with functionality. In order to verify the influence of the strength training with different types of contractions on parameters of structure and muscular function and functionality, a systematic review of studies involving lower limb strength training in the elderly, performed on isokinetic dynamometers, was carried out in Chapter 3. We found that both concentric and eccentric strength training have positive effects on muscle function and functionality. However, functional capacity was investigated in only one study, while muscle structure in none of them. In addition, no studies performed a strength training combining different types of contraction, which could be more beneficial for older individuals. Therefore, Chapter 4 presents preliminary data from the study involving strength training for elderly men where one group performed exclusively concentric training and another concentric-eccentric training for knee flexors and extensors. Subjects were assessed for the same parameters of Chapter 2 at three different times: baseline, two weeks after baseline assessment and after training. Preliminary results indicate that both groups presented muscular and functional gains after the training period.