# Low-Intensity Whole-Body Vibration: A Useful Adjuvant in Managing Obesity? A Pilot Study
## 1 Introduction  
Excessive body weight increases mechanical stress to the joints and tissues and induces physical limitations and pain [1], leading to a reduction in physical activity that contributes to the loss of muscle mass and strength. Weight loss is conventionally achieved through dietary modifications [2] behavioral correction, and/or exercise prescription [3]. In individuals with obesity, a modest weight loss (5-10% of body weight) helps to alleviate cardiovascular risk [2]. However, the success rate of therapy for obesity is very low: dieting may work in the short term, but severe dietary restriction alone reduces muscle mass andleads to a decline in physical fitness [4]; traditional exercise, such as aerobic and resistance training, improves heart rate variability, physical strength, and body composition. Pain is one of the major determinants of ceasing physical activity [1; 5]. Aerobic or resistance exercise can be associated with increased risk of musculoskeletal injuries, thus reducing adherence to exercise prescription [5]. In the last two decades, whole-body vibration (WBV) emerged as an alternative exercise modality for strength training [6]. WBV involves exercising on a vibrating platform. The vibrations mechanically generate rapid variations in the length of the muscle-tendon complex [7], stimulating repetitive eccentric-concentric muscular work and reflexive muscle contractions [8]. WBV was first recognized as an alternative to resistance exercise for its ability to enhance force and power in skeletal muscle [6; 9]. On the other hand at a molecular level, vibrations lead to the formation of ROS (reactive oxygen species) including hydrogen peroxide in water and biological fluids [10]. A moderate level of ROS induces the body's positive adaptive responses. At the same time it has been known that a high dosage of ROS leads to a decrease in muscle protein synthesis [11]. A major problem in the field is that the different stimulus intensities and safety of WBV devices are often poorly described [12]. The empirical foundation for reporting guidelines for human WBV studies was published only this year. It established a final 40-item panel of the aspects of WBV studies [13] expanding previous recommendations on the use of WBV [14]. However, vibration can have adverse effects on a number of physiologic systems and concern about potential risks for musculoskeletal [15; 16], circulatory and neurological disorders [17]; [PERSON]'s phenomenon [18] after exposure to WBV is still present in the literature. Vibration thresholds for human exposure during a work shift have been explicated in the International Standards Organization ISO-2631 recommendations and are in use only in the field of occupational medicine [17]. Despite the growth of WBV as a surrogate or supplement to exercise, no similar limits have been set so far for its use in rehabilitation [17]. It is true, however, that exposure to vibration during a rehabilitation session is constrained within some minutes of exercise repeated daily for different training durations, whereas occupational exposure is spread throughout the daily work shift and therefore, comparison between the levels of exposure is difficult. WBV training modality is characterized by several variables: frequency (Hz), type of vibration (rotating or vertical), amplitude in terms of displacement (mm) or, acceleration (g), exposure time and knee flexion grade, series, number of repetitions, rest period, frequency and duration [19]. In some WBV studies, the acceleration delivered by whole body vibration devices at the plantar surfaces of standing subjects and transmitted through the axial and appendicular skeleton exceeded the safety threshold limit values established by the International Standards Organization ISO-2631 [8; 17]. The use of WBV for therapeutic purposes appears, therefore, far from being standardized and caution should be used when using WBV devices providing high vibration levels on patients [17].