Comparison between whole body vibration and static resistance training in postmenopausal women : long-term effects on quadriceps muscle volume and power

Introduction. Reductions in muscle mass, force and peak power occurring with aging markedly affect the quality of life of elderly people, particularly regarding the performance of daily activities such as walking, stair negotiation and standing up. However, resistance training has been shown to play a useful role in counteracting these impairments. Recently, Whole Body Vibration (WBV) exercise has been promoted as an alternative and feasible method to enhance strength and muscle performance. Although WBV seems to acutely increase muscle strength and power, its long-term efficacy on muscle structural and functional properties is still controversial and strictly controlled studies are lacking in literature (Rehn et al. 2007). Whether WBV is effective in combating sarcopenia and muscle weakness in old age is thus unknown. Aim of the study. The aim of this research was to compare the long-term effects of a pure vibration training regime with an exercise protocol based on the same type of resistance training without vibration in order to identify the possible differences due to the vibration itself. Because elderly women are known to be at greater risk of losing functional independence than elderly men (Skelton et al. 1994), this study was performed in a population of post-menopausal women. Material and methods. Eleven postmenopausal, recreationally active women, were assigned either to a vibration training group (VT, n=7, mean ± S.D: age 67.7±6.3 years, BMI 23.2±2) or to a control training group (CT, n=4, mean ± S.D: age 68.2±8.8 years, BMI 30.7±5.6). The VT underwent static isometric training on a vibration platform (Galileo Fitness ©, Novotec Maschinen GmbH, Germany) 3 times per week for 8 weeks. Each session consisted of four sets of ten isometric semi-squats lasting ten seconds (80° of knee flexion) on the vibration platform at 30 Hz (amplitude: 0–5.2 mm), with ten seconds rest off the platform between each repetition. The CT undertook the same protocol but without vibration. During the workout all participants wore a weighted vest corresponding to 60% of one repetition maximum (1 RM), assessed weekly with a leg extension machine, in order to increase the intensity of the exercise. Quadriceps muscle volume (MV) assessed by magnetic resonance imaging, relative peak power (RP), peak power per muscle volume (PV) and height (JH) assessed during counter-movement jumps performed on a force platform (Leonardo ©, Novotec Medical, Pforzheim, Germany), were measured before and after the training periods. Results. Between pre- and post-training VT and CT showed a non significant increase in MV by 3.3 and 4.9%, and in RP by 3.9 and 3.8% respectively (p>0.05). PV did not change in VT and slightly decreased (-2%) in CT in a non significant manner (p>0.05). JH did not show any change. Furthermore, no significant differences were found between the two training groups (p>0.05). Conclusion. The results of this study suggest that whole body vibration, associated with strength training, does not produce greater gains in muscle volume and power than strength training alone. We cannot exclude that with a training period longer than the present one (8 weeks) or targeting an elderly population of older age, greater benefits may be seen. A noteworthy and positive observation is that none of the elderly participants found WBV uncomfortable. Keywords: vibration, training, postmenopausal, muscle volume References Rehn B, Lidström J, Skoglund J, Lindström B. Effects on leg muscular performance from whole-body vibration exercise: a systematic review. Scand J Med Sci Sports 2007; 17: 2–11 Skelton DA, Greig CA, Davies JM, Young A. Strength, power and related functional ability of healthy people aged 65–89 years. Age Aging 1994; 23: 371–7