The Effects of Six Weeks of Unloaded and Loaded Whole-Body Vibration Training on Arterial Function and Muscle Strength in Obese Pre-Menopausal Women

• Other Authors: Alvarez-Alvarado, Stacey (authoraut)
• Format: Others
• Language: English; English
• Published: Florida State University
• Subjects: Physiology; Kinesiology; Medical sciences
• Online Access: http://purl.flvc.org/fsu/fd/FSU_migr_etd-9130

Background: Obesity is an ongoing socio-economic worldwide epidemic and major modifiable risk for cardiovascular disease (CVD), which continues to be the main determinant of all-cause mortality. A potential mechanism by which obesity associates with CVD is an increased stiffness of the arteries leading to a decreased vascular function and development of hypertension. Moreover, muscle strength and mass are inversely related to arterial stiffness and obesity. Although exercise training is a proficient intervention for treating CVD risk factors and increasing muscle strength/mass, the most effective intervention for decreasing arterial stiffness is still unclear. Whole-body vibration training (WBVT) is a relatively novel exercise mode which requires static or dynamic movements on a vibrating platform and has similar adaptations in the skeletal muscle as resistance training (RT). However, the effects of whole-body high intensity RT seem to be adverse, although controversial to arterial function in young healthy adults and middle-aged with prehypertension or hypertension. WBVT is usually performed with leg exercises using the body weight (unloaded) as resistance to the exercise. However, the addition of an external load or resistance to WBVT (WBVT+EX) has shown beneficial adaptations in improving arterial function, bone mineral density, hormonal responses, and muscle strength/mass. Purpose: The purpose of this study was to evaluate whether WBVT+EX would induce greater benefits than unloaded WBVT on arterial function and muscle strength in young-overweight and obese (body mass index, BMI= 30.9 ± 0.7 kg/m²) women. Methods: Twenty-two young (20 ± 1 yr) overweight/obese women were randomly assigned to a non-exercising overweight/obese control (O-CON), WBVT, or WBVT+EX for 6 weeks. Thirteen lean women were assigned to a lean control (L-CON) group in order to compare them at baseline to the age-matched overweight/obese women. Pulse wave velocity (PWV), brachial blood pressure (BP), aortic BP, wave reflection, muscle strength, and body composition were measured before and after 6 weeks. Results: Statistical significance was set at P < 0.05. Data were presented as mean ± SE. There were no significant time effects or group-by-time interactions for brachial-ankle PWV (baPWV), carotid-femoral PWV (cfPWV), brachial systolic BP (bSBP), brachial diastolic BP (bDBP), aortic diastolic BP (aDBP), augmentation index (AIx), augmentation pressure (AP), and transit time for the reflected wave (Tr). cfPWV and aSBP decreased (P < 0.05) in the WBVT group while baPWV and aDBP decreased in the WBVT+EX. There was a significant group-by time interaction (P < 0.01) for faPWV, aSBP, aortic mean arterial pressure (aMAP), and AIx adjusted at 75 bpm (AIx@75). In addition, group-by-time interaction was detected for P1 and P2 such that the reductions observed in the WBVT and WBVT+EX groups were significantly different (P < 0.05) from the O-CON group. The WBVT and the WBVT+EX groups had significant increases in leg strength (P < 0.01) when compared to the O-CON group (group-by-time P < 0.01) while a time-effect (P < 0.01) was observed in the chest 1RM only in the WBVT+EX group. Conclusion: To our knowledge, this is the first study to detect beneficial effects of WBVT+EX on arterial parameters, as shown by improvements in aortic BP, PWV, and wave reflection while still maintaining increases in muscle strength in young overweight/obese women. Although unloaded WBVT seems to be an effective exercise modality to improve arterial function in obese postmenopausal women, it does not seem to be as efficient in young obese women. This study suggests that, although WBVT had some positive effects on arterial function in young overweight/obese women, a more evident benefit on arterial function is observed after increasing the exercise intensity of WBVT through an external load progressed from 15 to 8 RM. Future studies should focus on older populations with greater risk of cardiovascular and/or other chronic diseases that are associated with reduced muscle strength/mass. WBVT+EX should be incorporated and recommended for young overweight/obese women in order to improve arterial function and prevent the loss in muscle mass related to weight loss. Additional studies should also consider the use of WBVT+EX as an adjunct exercise modality in order to incorporate its use in clinical populations prone to physical disabilities due to sarcopenia and dynapenia. === A Thesis submitted to the Department of Nutrition, Food, and Exercise Sciences in partial fulfillment of the requirements for the degree of Master of Science. === Fall Semester, 2014. === November 3, 2014. === Arterial stiffness, Cardiovascular diseases, Obesity, Whole-body vibration training === Includes bibliographical references. === Arturo Figueroa, Professor Directing Thesis; Diana Williams, Committee Member; Michael Ormsbee, Committee Member.