تمرین آویزی TRX: یک رویکرد تمرینی کارکردی جدید برای بزرگسالان مسن – توسعه، کنترل تمرین و امکان سنجی TRX Suspension Training: A New Functional Training Approach for Older Adults – Development, Training Control and Feasibility

ABSTRACT International Journal of Exercise Science 8(3): 224-233, 2015. Because of its proximity to daily activities functional training becomes more important for older adults. Sling training, a form of functional training, was primarily developed for therapy and rehabilitation. Due to its effects (core muscle activation, strength and balance improvements), sling training may be relevant for older adults. However, to our knowledge no recent sling training program for healthy older adults included a detailed training control which is indeed an essential component in designing and implementing this type of training to reach positive effects. The purpose of this study was to develop a TRX Suspension Training for healthy older adults (TRX-OldAge) and to evaluate its feasibility. Eleven participants finished the 12 week intervention study. All participants trained in the TRX-OldAge whole-body workout which consists of seven exercises including 3-4 progressively advancing stages of difficulty for every exercise. At each stage, intensity could be increased through changes in position. Feasibility data was evaluated in terms of training compliance and a self-developed questionnaire for rating TRX-OldAge. The training compliance was 85 %. After study period, 91 % of the participants were motivated to continue with the program. The training intensity, duration and frequency were rated as optimal. All participants noted positive effects whereas strength gains were the most. On the basis of the detailed information about training control, TRX-OldAge can be individually adapted for each older adult appropriate to its precondition, demands and preference. INTRODUCTION The aging process of skeletal muscles is characterized by a reduced number of motor units, muscle fibers and size of type 2 fibers that lead to a loss of muscular strength and power (32). Furthermore, deteriorated proprioception (14, 1) and reaction time (6) were observed with increasing age. These age-related changes result in strength, balance, and mobility declines (13, 7, 8, 3, 2), which could induce falls or a loss of independence (28, 18). It is recommended for older adults to perform regular physical activity to avoid functional limitations (22). Beyond that, exercise intervention studies have demonstrated positive effects on strength, balance, and functional performance for older adults (10, 17, 29). Traditional strength training with weight machines for older adults has been shown to increase muscular strength (29), balance performance if lower limb muscles were trained (17), and functional tasks (10). In past years, sport science has tended to focus on functional strength training for older adults, because it is geared to daily life movements (performing complex movements with own body weight). Compared to traditional resistance training, previous studies showed a similar one repetition maximum (1RM) increase (29, 19) and a significant improvement in the sit-tostand test (19) through functional resistance training, whereas the weight machine group did not change significantly. For maximal walking speed, a significant enhancement was observed within the functional strength training but not within the traditional resistance training group (29). During a reaction task, older adults participating in functional resistance training significantly enhanced their movement time whereas training with weight machines could not achieve this result (33). Strength improvements from traditional resistance training alone and with additional functional (strengthening) exercises are similar (11). However, compared to traditional strength training alone, timed performance of functional abilities like chair rising or stair climbing (20) and balance (5) only changed with additional functional exercises during strength training. Core stability training is a sort of training that combines both functional and strength components. By strengthening core muscles an optimal load transmission from upper to lower body can be realized (34). This can result in better core stability and balance. Because of these effects, functional core stability training programs were conducted in previous intervention studies for older adults (12, 9). One possible core stability program is called sling training. Previous studies focusing on patients with low back pain indicated an increased trunk muscle activation of transversus abdominis, internal oblique, rectus abdominis, multifidi and erector spinae during exercises with a sling trainer (15, 25). In studies with younger adults, both improvements in muscular strength (4, 24) and balance (16, 23) were observed. In regard to older adults, however, there is less evidence from intervention studies implementing sling training. The existent studies with older participants examined osteoporosis and knee osteoarthritis patients (26, 27, 31). Based on the positive effects of sling training on balance and strength parameters in younger adults and patients, this kind of training may be suitable for healthy older adults. However, to our knowledge no sling training program for this target group exists. Therefore the purpose of this study was to develop a detailed exercise prescription for a wholebody sling training program for healthy older adults and to analyze its feasibility. This pilot study provides information about feasibility and practicability of the TRX Suspension Training program developed for older adults (TRX-OldAge).