A three month controlled intervention of intermittent whole body vibration designed to improve functional ability and attenuate bone loss in patients with rheumatoid arthritis

Background: Rheumatoid arthritis (RA) is a chronic autoimmune condition that results in pain and disability. Patients with RA have a decreased functional ability and are forced into a sedentary lifestyle and as such, these patients often become predisposed to poor bone health. Patients with RA may also experience a decreased health related quality of life (HRQoL) due to their disease. Whole body vibration (WBV) is a form of exercise that stimulates bone loading through forced oscillation. WBV has also been shown to decrease pain and fatigue in other rheumatic diseases, as well as to increase muscle strength. This paper reports on the development of a semi randomised controlled clinical trial to assess the impact of a WBV intervention aiming to improve functional ability, attenuate bone loss, and improve habitual physical activity levels in patients with RA. Methods/Design: This study is a semi randomised, controlled trial consisting of a cohort of patients with established RA assigned to either a WBV group or a CON (control) group. Patients in the WBV group will undergo three months of twice weekly intermittent WBV sessions, while the CON group will receive standard care and continue with normal daily activities. All patients will be assessed at baseline, following the three month intervention, and six months post intervention. Main outcomes will be an improvement in functional ability as assessed by the HAQ. Secondary outcomes are attenuation of loss of bone mineral density (BMD) at the hip and changes in RA disease activity, HRQoL, habitual physical activity levels and body composition. Discussion: This study will provide important information regarding the effects of WBV on functional ability and BMD in patients with RA, as well as novel data regarding the potential changes in objective habitual physical activity patterns that may occur following the intervention. The sustainability of the intervention will also be assessed

In Patients with Established RA, Positive Effects of a Randomised Three Month WBV Therapy Intervention on Functional Ability, Bone Mineral Density and Fatigue Are Sustained for up to Six Months

Functional ability is often impaired for people with rheumatoid arthritis (RA), rendering these patients highly sedentary. Additionally, patients with RA often take medication known to negatively affect bone mass. Thus improving functional ability and bone health in this group of patients is important. The aim of this study was to investigate the effects of whole body vibration (WBV) therapy in patients with stable, established RA. Thirty one females with RA were randomly assigned to a control group (CON, n = 15) who continued with their normal activities or a WBV group (n = 16) who underwent a three month WBV therapy intervention, consisting of 15 minutes of intermittent vibration, performed twice per week. Patients were assessed at baseline, three months, and three months post intervention for functional ability using the modified Health Assessment Questionnaire; for RA disease activity using the Clinical Disease Activity Index, for quality of life using self-report fatigue and pain scores; for physical activity profiles using accelerometry, and for BMD and body composition using DXA. Patients in both groups were matched for all variables at baseline. After the intervention period, functional ability was significantly improved in the WBV group (1.22(0.19) to 0.92(0.19), p = 0.02). Hip BMD was significantly reduced in the CON group (0.97(0.05) to 0.84(0.05) g.cm-2, p = 0.01), while no decreases were seen in the WBV group (1.01(0.05) to 0.94(0.05) g.cm-2, p = 0.50). Despite no change in RA disease activity in either group at either follow up, fatigue levels were improved in the WBV group (4.4(0.63) to 1.1(0.65), yet remained unchanged in the CON group at both follow ups (p = 0.01). Ten minute bouts of light to moderate physical activity were significantly reduced in the CON group after the intervention (2.8(0.61) to 1.8(0.64) bouts per day, p = 0.01), and were preserved in the WBV group (3.1(0.59) to 3.0(0.61) bouts per day, p = 0.70). Intermittent WBV shows promise for sustained improvements in functional ability, for attenuating loss of bone mass at the hip, as well as for decreasing fatigue in patients with established RA. TRIAL REGISTRATION: Pan African Clinical Trials Registry PACTR201405000823418

High-Frequency, Low-Magnitude Vibration Does Not Prevent Bone Loss Resulting from Muscle Disuse in Mice following Botulinum Toxin Injection

High-frequency, low-magnitude vibration enhances bone formation ostensibly by mimicking normal postural muscle activity. We tested this hypothesis by examining whether daily exposure to low-magnitude vibration (VIB) would maintain bone in a muscle disuse model with botulinum toxin type A (BTX). Female 16–18 wk old BALB/c mice (N = 36) were assigned to BTX-VIB, BTX-SHAM, VIB, or SHAM. BTX mice were injected with BTX (20 µL; 1 U/100 g body mass) into the left hindlimb posterior musculature. All mice were anaesthetized for 20 min/d, 5 d/wk, for 3 wk, and the left leg mounted to a holder. Through the holder, VIB mice received 45 Hz, ±0.6 g sinusoidal acceleration without weight bearing. SHAM mice received no vibration. At baseline and 3 wk, muscle cross-sectional area (MCSA) and tibial bone properties (epiphysis, metaphysis and diaphysis) were assessed by in vivo micro-CT. Bone volume fraction in the metaphysis decreased 12±9% and 7±6% in BTX-VIB and BTX-SHAM, but increased in the VIB and SHAM. There were no differences in dynamic histomorphometry outcomes between BTX-VIB and BTX nor between VIB and SHAM. Thus, vibration did not prevent bone loss induced by a rapid decline in muscle activity nor produce an anabolic effect in normal mice. The daily loading duration was shorter than would be expected from postural muscle activity, and may have been insufficient to prevent bone loss. Based on the approach used in this study, vibration does not prevent bone loss in the absence of muscle activity induced by BTX

CIRCADIAN RHYTHM VARIATION IN ENDOCRINE BIOMARKER RESPONSES TO HIGH-INTENSITY INTERVAL TRAINING IN COLLEGE AGED MALES

Cyrus Shuler1, Michael G. Bemben1, FACSM, Rebecca Larson1, Michael Pham1, Chinguun Khurelbaatar1, & Debra A. Bemben1, FACSM 1University of Oklahoma, Norman, Oklahoma Circadian rhythms are critical for regulating physiological and behavioral responses during a 24-hour solar cycle. Testosterone (T) and Cortisol (C) are commonly measured as biomarkers of physiological adaptations to exercise, as the T:C ratio is indicative of an anabolic:catabolic state based on their physiological effects on specific tissues. Recently, high-intensity interval training (HIIT) has emerged as an exercise method shown to yield greater improvements in aerobic fitness compared to traditional steady-state aerobic exercise, yet little is known about its effects on hormonal responses. PURPOSE: To examine the effects of time of day on salivary testosterone (sal-T) and salivary cortisol (sal-C) responses to acute bouts of HIIT performed in the morning (AM) and evening (PM), and to examine diurnal variations in the T:C ratio responses to HIIT in college aged men (n=10). METHODS: A 1:2 minute ratio (Work:Recovery) HIIT protocol was employed (W 81% VO2peak, R 40% of VO2peak). Salivary samples were collected prior to (PRE) and immediately post (IP) each exercise session. Salivary samples also were collected for the control day in the AM and PM on the same day to establish baseline hormone concentrations. All salivary samples were assayed using Salimetrics kits at the Salivalab in Carlsbad, California. Testing order was randomized. RESULTS: A significant exercise main effect was observed for sal-T, which increased PRE to IP for both AM and PM sessions (AM PRE: 274.34 ± 91.39 pg/mL; AM IP: 292.16 ± 87.65 pg/mL vs. PM PRE: 233.83 ± 70.50 pg/mL; PM IP: 281.47 ± 93.78 pg/mL, p = 0.041). Sal-C had a significant time of day main effect as the PM session had lower values for both PRE and IP than the AM session (AM PRE: 0.463 ± 0.348 µg/dL; AM IP: 0.491 ± 0.380 µg/dL vs. PM PRE: 0.210 ± 0.110 µg/dL; PM IP: 0.297 ± 0.244 µg/dL, p = 0.029). The T:C ratio also had a significant time of day main effect (AM PRE: 0.083 ± 0.044; AM IP: 0.085 ± 0.043 vs. PM PRE: 0.132 ± 0.056; PM IP: 0.140 ± 0.073, p = 0.013). CONCLUSION: Sal-T responses to acute bouts of HIIT were not affected by time of day; however, sal-C concentrations were lower in the PM session resulting in a more favorable T:C ratio in the afternoon. These findings suggest performing HIIT in the late afternoon may be more beneficial for physiological adaptations

EXERCISE-INDUCED MUSCLE DAMAGE AND THE REPEATED-BOUT EFFECT: ROLE OF THE RELATIONSHIP BETWEEN MOTOR-UNIT FIRING RATE AND RECRUITMENT THRESHOLD

Robert E. Hight, Travis W. Beck, Debra A. Bemben, FACSM, and Christopher D. Black. Department of Health and Exercise Science, University of Oklahoma, Norman, OK; e-mail: [email protected] Unaccustomed eccentric exercise results in exercise-induced muscle damage. Following an acute bout of damaging exercise, an adaptation occurs which significantly attenuates the magnitude of muscle damage induced by future bouts of eccentric exercise. This phenomenon is termed the “repeated-bout effect (RBE).” There is evidence neural adaptations may underlie the RBE, however, the specific changes in motor-unit recruitment strategies remain unclear. PURPOSE: The primary aim of this study was to examine changes in motor-unit activation (mean firing rate, recruitment threshold, and their inter-relationship) of the biceps brachii 3 weeks following a bout of eccentric exercise. METHODS: Nine participants performed 5 sub-maximal isometric trapezoid (ramp-up, hold, ramp-down) contractions at force levels corresponding to 50, 80, and 100% maximal isometric strength (MVC). Surface EMG signals of the biceps brachii were collected and decomposed into individual motor-unit action potential trains. The relationship between mean firing rate (MFR) of each motor-unit and the percent of MVC at which it began firing (recruitment threshold; RT) was examined using linear regression. Participants then performed an exercise protocol consisting of eccentric dumbbell curls with a weight corresponding to 120% of concentric 1-RM until MVC had decreased by ~40%. Indirect markers of muscle damage [MVC, range-of-motion (ROM), and delayed onset muscle soreness (DOMS)] were measured 24-hours, 72-hours, and 1-week following eccentric exercise. Three weeks later all procedures were repeated. RESULTS: A RBE was observed with a second bout of eccentric exercise resulting in smaller reductions in MVC (-32±14% vs -25±10%; p=0.034) and ROM (-11% vs 6%; p = 0.01), and reduced soreness (31.0±19mm vs 19±12mm; p=0.015) compared to the initial bout of eccentric exercise. When compared to the initial assessment, a decrease in the slope (-0.60±0.13 vs -0.70±0.18; p=0.029) and increase in the y-intercept (46.5±8.3 vs 53.3±8.8; p=0.020) of the MFR vs. RT relationship during contractions at was observed during contractions at 80% of MVC prior to the second bout of eccentric exercise. No changes were observed at 50% or 100% of MVC. CONCLUSION: These findings indicate a long lasting shift in the relationship between MFR and RT of motor-units after the induction of muscle damage occurs concomitant with the RBE. The observed shift is consistent with preferential activation of slow-twitch motor-units which have been shown to be less susceptible to damage than fast-twitch fibers. These findings support the hypothesis that neural adaptations, at least partially, underlie the RBE