Whole body vibration (WBV) is a mode of exercise by which an individual stands on a vibration platform that may be oscillating and therefore creating vertical displacement which affects gravitational forces acting upon the whole body. Manipulations of platform amplitude or frequency can affect the rate of change of the WBV (i.e. acceleration) acting upon an individual. The specific influences of frequency or amplitude, however, are unknown. The aim of the study, therefore, was two fold; (1) to identify chronic WBV effects of neuromuscular performance within a community dwelling older adult sample, and; (2) to identify WBV methods that would elicit chronic neuromuscular performance changes within such a sample. The study incorporated a randomised controlled experimental design to examine the aim. Seventy-three community dwelling older adults freely consented to the requirements of the study (mean age = 72.0 years). Neuromuscular performance was quantified with the 5-Chair Stands test, the Timed Up and Go (TUG) test and the Tinetti test. Health Related Quality of Life (HRQOL) was qualified with the SF-36 Health Survey. A six week WBV intervention significantly changed the quantifiers of neuromuscular performance in a community dwelling older adult sample. The WBV intervention significantly reduced time taken to complete the 5-Chair Stands test (p <.05) and the TUG test (p <.05). The six week WBV intervention significantly improved Tinetti test scores (p <.05). The six week WBV intervention significantly improved all components of HRQOL. For the 5-Chair Stands test, a three WBV sessions per week intervention elicited significantly larger (p <.05) neuromuscular performance gains than a two WBV sessions per week intervention in the target sample. For the TUG test, a three WBV sessions per week intervention elicited significantly larger (p <.05) neuromuscular performance gains than a zero and one WBV session per week intervention in the target sample. A significant difference (p <.05) was found between pre-test and post-test Tinetti test scores for all WBV intervention groups. There was an insignificant difference (p >.05) found within the control group of community dwelling older adults for the Tinetti test. Detraining effects were observed three weeks after the cessation of the six week WBV intervention for the three WBV sessions per week group. Neuromuscular performance reduced after the detraining period. Vibration platform dynamics (manipulated frequency and controlled amplitude) showed that gravitational forces created by the WBV were safe since no injuries were associated with the intervention and since participant compliance was 100% during the six week WBV intervention. The methods of this study showed a chronic WBV intervention to be a safe and easily administered exercise to improve neuromuscular performance and HRQOL of a community dwelling older adult sample. Specifically, WBV could be used as a safe and effective tool to improve aspects of normal daily function such as body balance and gait speed.

Gymnasts must attain extreme ranges of flexibility to execute performance requirements, thus effective stretching proves vital to advancement in the sport. This study examined the acute effects of whole-body vibration (WBV) on passive and dynamic flexibility in young, female gymnasts. Participants (n = 27, Junior Olympic levels 5-10) served as their own control. Measurements of passive and dynamic flexibility were obtained using the TOPS forward split testing method to examine passive flexibility and dynamic flexibility was measured via split jumps that were analyzed with video and Dartfish software. According to randomized order, all participants completed a stretching protocol either with the WBV platform turned on (VIB) or off (C) separated by 48 h. Participants performed 4 sets of three stretches on the WBV platform. An ANCOVA was performed (using height, weight, age, years of experience, and gymnastics level as covariates). Significant improvements were found in passive flexibility for both VIB and C conditions, but there was no significant difference between the two stretching conditions (p = 0.17). The maximum split jump decreased significantly from pre to post measurement in both the VIB (p < 0.0001) and C (p = 0.04) conditions. VIB decreased the split jump significantly more than C. Based on the results of our study, an acute session of static stretching or stretching with WBV immediately before performance decreases split jump performance. Therefore, this WBV protocol is not recommended immediately prior to gymnastics competition.

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Low back pain is a leading cause of disability and is associated with whole-body vibration exposure in industrial workers and military personnel. The pathophysiological mechanisms by which whole-body vibration causes low back pain have been studied in vivo, but there is little data that improve diagnosis of low back pain. The overall objective of this research was to elucidate diagnostic biomarkers associated with whole-body vibration. Hence, a rat model for vibration-induced inflammatory responses was developed. Von Frey filaments were used to determine the withdrawal threshold of the hind paw as a surrogate behavioral marker for pain. The concentration of nerve growth factor in the serum was measured every four days using an assay as a potential diagnostic biomarker for low back pain. In the first study, whole-body vibration was applied using a modified commercially available device at 8 or 12 Hz every other day for two weeks, following which animals recovered for one week. At the conclusion of the study, intervertebral discs were graded histologically for degeneration. The nerve growth factor concentration increased threefold in the 8 Hz group and twofold in the 12 Hz group and returned to baseline by the end of the recovery period for 12 Hz, but not 8 Hz. Mechanical sensitivity appeared to change over time due to habituation and not any effect of vibration and was inconclusive. There was no difference in intervertebral disc degeneration scores between groups. In the second study, rats were vibrated at 8 Hz every other day for two or four weeks. The concentrations of nine cytokines were determined in the longissimus muscle, spleen, and thymus using a multiplex assay. These cytokines were ranked according to their ability to differentiate vibrated and non-vibrated animals, and classification models were compared. Nerve growth factor serum concentration peaked on day 13, then returned to baseline on day 17. The withdrawal threshold in vibrated animals decreased throughout the study indicating greater sensitivity to the stimulus, a surrogate for increased pain. Several longissimus muscle and spleen cytokines were important in distinguishing vibrated animals from non-vibrated, while thymus cytokines and weeks of exposure were not significant.

Vibration exposure can occur at work, commuting between home and work, and in leisure activities. Any form of transportation will expose humans to some degree of vibration. Exposure to vibration can cause health problems, but more likely comfort problems. Health problems are normally related to back pain. Comfort on the other hand is related to both physiological and psychological factors, which can have a wide range of effects from a general annoyance to a reduced work capability. The standard ISO 2631-1 (1997) provides a guidance, which can be used to measure, evaluate and assess effects of whole-body vibration to discomfort. The standard allows several interpretations, which can lead to different results, as the standard does not provide an explicit guidance for selecting which axes and locations to measure and which averaging method to use for evaluating the axes. The suggested averaging method is the root mean square (r.m.s.) method, but additionally vibration dose value (VDV) can be used. This can lead to different results, as VDV emphasises shocks more than the r.m.s. method. The standard guides to measure and evaluate at least the seat translational axes, but the additional nine axes from the seat, backrest and floor are not mandatory. However, this can result in a different comfort value, as the values from the measured axes are combined. So taking into account all possible interpretations the assessment can vary significantly for the same environment. The selection of the averaging method is not a technical issue, as both methods are supported by all commercial equipment. However, it is rare that more than three axes are possible to be measured with typical whole-body vibration measurement equipment, thus the majority of studies have published results based on only the seat translational axes. Especially the rotational axes have been missing in most studies. The full method (i.e. using all possible axes to calculate the comfort value) of ISO 2631-1 (1997) has been rarely used and there is very little information on how accurate the method is for assessing discomfort in a multi-axis environment. There are only a few studies that have used the full method, but there are no known studies which have actually validated the full ISO 2631-1 method. The objective of the thesis was to validate and, if necessary, to improve the full method of the ISO 2631-1 standard for evaluating discomfort from whole-body vibration in a multi-axis environment. It was assumed that the ISO 2631-1 method can be used to predict discomfort in practice, but there are a relatively low number of studies to confirm this. Frequency weightings have been the focus of many published studies and it was assumed that these are broadly correct. Other aspects of the ISO 2631-1 method are the focus of this thesis. The goal was to keep a backward compatibility to previous studies and the current commercial equipment, thus several limitations were defined for the improvement of the standard. Several laboratory experiments, field measurements, and field and laboratory trials were conducted to validate the standard method. At first it was concluded that practical equipment for measuring 12-axis data was needed as there was no commercial system available. The equipment and software was validated in two experiments, which showed that simple and affordable components could be used to develop equipment for the full method. Even though the standard does not include information about a six-axis sensor for measuring both translational and rotational axes, there was a method to validate the sensor. The first field study included measuring several machines using all twelve axes. The analysis showed that the seat and backrest translational axes will contribute about 90 % of the overall vibration total value of the standard method, thus very little justification was found for including the seat rotational and floor translational axes. Similar results were found based on the data from the previous 12-axis studies. It was also found that the neglected axes could be compensated with a factor for estimating the overall vibration total value including all twelve axes. As the overall vibration total value is directly related to the number of used axes, the compensating factors can be used to compare results which used different axes. The laboratory trial confirmed the results from the field study, and it was concluded that sufficient accuracy to predict discomfort can be achieved using just the seat translational axes, even though the correlation improved when more axes were included. It was found that the evaluation of discomfort was improved by the use of the frequency weighting curves and the r.m.s. averaging method. However, as the multiplying factors degraded correlation, it was concluded that a new set of factors should be calculated. The new factors showed that a higher emphasis on the seat horizontal axes should be given (x=2.7, y=1.8 and z=1.0). The new factors improved the correlation systematically for all subjects. The field trial showed a similar trend, where optimised multiplying factors improved the correlation, but it was also noted that different multiplying factors are required for different environments, thus a procedure to optimise the standard method to different environments was developed. The trial showed systematic behaviour and the optimised multiplying factors were best for all subjects and groups. Keywords: Discomfort, whole-body vibration, standard, ISO 2631-1, multi-axis, multiplying factors

MPH, Occupational Hygiene, Faculty of Health Sciences, University of the Witwatersrand / Introduction Locomotive operators in the mining industry are exposed to high levels of noise and vibration. There is currently limited information indicating whole-body vibration exposure levels conducted over an 8-hour time weighted average (TWA) exposure period; most of the available data are based on instantaneous measurements. The 10-Ton New Era locomotive was specifically designed with the focus on areas such as ergonomics, safety, future automation, productivity and flexibility of use. The locomotive has a single cab and can be driven and controlled with maximum visibility in the direction of travel. Most mining houses are converting from the use of the 10 Ton Goodman battery operated locomotive to the 10Ton New Era locomotive, hence the focus of noise and vibration measurements on the latter. Objectives This research report documents a project to measure noise and whole-body vibration exposure levels of locomotive operators working in an underground platinum mine. The objectives of the study are: • to describe the eight hour time weighted average occupational noise exposure levels of locomotive operators operating the 10-Ton New Era locomotive in an underground platinum mine over 2008 and 2009; • to describe personal whole-body vibration exposure levels of locomotive operators operating the 10-Ton New Era locomotive in an underground platinum mine over 2008 and 2009; and 5 • to determine whether personal noise and whole-body vibration exposure levels of locomotive operators operating the 10-Ton New Era locomotive in an underground platinum mine over 2008 and 2009 comply with national and international standards. Methods Personal noise and whole-body vibration exposure measurements were obtained from 21 underground locomotive operators. Measurements were conducted in accordance with the procedures described in the SANS 10083 standard for personal noise dosimetry and the ISO 2631-1 standard for whole-body vibration. Determination of likely health risks for the operators were based on a comparison of the measured time-weighted noise exposure levels with the South African OEL and the ACGIH threshold limit value; whole-body vibration levels were compared with the HGCZ limits presented in Annex B of the ISO 2631-1 standard and the EU directive daily exposure limits. Results The measured noise and whole-body vibration levels taken over an 8-hour TWA exposure period were higher when compared to national and international standards. The mean LTWA levels for noise was 66.5 dB(A) with 12.5% of the measurements exceeding the South African OEL of 85dB(A). 45% of the wholebody vibration measurements fell within the HGCZ indicating that whole-body vibration exposure on locomotive operators presents a moderate probability for an adverse health outcome. Discussion and Conclusion Locomotive operators are exposed to potentially harmful levels of noise and whole-body vibration. The Mine Health and Safety Act requires an employer to assess the health and safety risks that hazards pose to their employees, and to take reasonably practicable steps towards eliminating or controlling those risks. Like any other risks at a workplace, noise and whole-body vibration needs to be 6 identified and controlled, and the approach to be taken is one of a risk management

Vehicle occupants are typically exposed to unpleasant whole-body vibration (WBV) for extended period of time. It is well known that the transmission of unwanted vibration to the human body can lead to fatigue and discomfort. Moreover, the unwanted vibration normally distributed in the low-frequency range has been found as the main risk factor for lower back pain and lumbago, which seriously affect the health and working performance of occupants. Thus vibration cancellation on seats has attracted considerable interest in recent years. So far, for most vehicle seats, vibration isolation is achieved passively by using seat cushions and conventional energy absorbers, which have very limited performance in the low-frequency range. The work presented in this thesis forms a successful development and experimental study of an active seat and control algorithm for occupants’ WBV reduction under low frequency excitations. Firstly, a modelling study of the seat human subjects (SHS) and an extensive experimental measurement of the vibration transmissibility of a test dummy and vehicle seat are carried out. The biodynamic responses of SHS exposed to uncoupled vertical and fore-and-aft WBV is modelled. A comparison with the existing models is made and the results show that an improved fit with the aggregated experimental data is achieved. Secondly, an active seat is developed based upon the observations and understanding of the SHS and seat system. The characteristics of the active seat dynamics are identified through experimental tests found suitable for the development of an active seat to attenuate the vibration experienced by vehicle occupants. The vibration cancellation performance of the active seat is initially examined by feedforward plus proportional-integral (PI) control tests. Through these tests, the effectiveness of the actuators control authority is verified, but the limitations are also revealed. Because the active seat system is subject to non-linear and time-varying behaviour, a self-tuning fully adaptive algorithm is a prime requirement. The Filtered-x Least-Mean-Square (FXLMS) algorithm with the Fast-block LMS (FBLMS) system identification technique is found suitable for this application and is investigated through experimental tests. Substantial vibration reductions are achieved for a variety of input vibration profiles. An excellent capability of the active seat and control system for efficiently reducing the vibration level of seated occupants under low-frequency WBV is demonstrated.

Background: Older adults walk more slowly than healthy young adults at fast and normal walking speeds. These age-associated changes in mobility impact upon daily function. A slower gait, for example, may reduce the older adult’s ability to safely cross at traffic intersections due to the time restriction. Recent research has demonstrated whole body vibration (WBV) can improve the strength and power (Roelants, Delecluse & Verschueren, 2004; Russo et al., 2003; Verschueren, Roelants, Delecluse, Swinnen, Vanderschueren & Boonen, 2004) of community dwelling elderly females, and the mobility of nursing home residents (Bautmans, Van Hees, Lemper & Mets, 2005; Bruyere et al., 2005). To date, no published research has examined the impact WBV has on the gait parameters of community dwelling elderly females. The research was conducted in three phases. Phase One – Development of a WBV Platform: This phase outlines the development of a WBV platform (ACUWBV) that was designed and built for this research. A unique aspect of the ACUWBV was the method of adjusting WBV amplitude and therefore intensity. Current WBV technology, using tilting oscillations, requires the individual to increase their stance width. The ACUWBV allowed for the adjustment of WBV amplitude while maintaining the same stance width. The reliability and accuracy of the ACUWBV eccentric cam was measured during this phase of the research. Although an intraclass correlation coefficient of 0.4 was calculated and is considered an indication of low reliability, calculations of typical error (TE -95% error range) for each amplitude indicated the error to be small in the overall precision of the instrument. Specifically, at a frequency of 20 Hz, the expected WBV acceleration ranges for amplitudes of 0.5 mm and 1.0 mm were 7.58 m.s-2 to 8.85 m.s-2 (TE = 0.02 mm) and 16.90 m.s-2 to 17.53 m.s.-2 (TE = 0.01 mm), respectively. Phase Two – Pilot Study: This phase established the response of elderly community-dwelling female fast gait to WBV. Seven elderly female participants attended three WBV sessions per week for three weeks. Participants performed fast walks over an electronic walkway (GAITRite) at the end of each WBV session. A time-series graph displayed a linear increase in stride velocity over the three week intervention period. Conversely, stride time, stance time and double support time exhibited linear decreases. However, stride time (p=0.04) and stance time (p=0.04) were the only variables that exhibited a significant difference. It was concluded that the linear changes in stride velocity, stride time, stance time and double support time warranted further investigation with a larger sample size within a longer intervention period. Phase Three – Major Study: Phase three was an extension of phase two. This WBV intervention study was performed over a twelve week period. Twenty-two elderly female participants were placed in one of two groups. Group one (placebo/WBV; Group; n=12) was exposed to a placebo intervention for the first six weeks followed by a six week WBV intervention. Group two (Group WBV/placebo; n=10) was exposed to WBV for the first six weeks and a placebo intervention for the following six weeks. Group placebo/WBV exhibited no change in stride velocity during the placebo period, but a seven per cent increase during the six week WBV period (p=0.005). The changes in stride velocity coincided with increases in stride length (p=0.017), and reductions in stride time (p=0.007), stance time (p=0.001) and double support time (p=0.001). Group WBV/Placebo demonstrated stride velocity to increase by five per cent during the WBV period. Although the time-series graphs demonstrated improvements in stride velocity to be associated with decreases in stride time, stance time, and double support time, the changes failed to reach significance. Single support time and stride length showed no change over the WBV period. The improvements shown by group WBV/placebo from the first six weeks of WBV were maintained during the six week placebo (detraining) period. In summary, WBV was an effective intervention for enhancing the walking speed of community dwelling elderly female gait. This form of exercise may have positive outcomes on the daily function of elderly females, which in turn may improve their quality of life.

<p>Abstract 1.</p><p>The purpose of this study was to investigate the effects whole body vibrations on maximal strength, power output and neuromuscular activity in m. pectoralis major during bench press.</p><p>Participants consisted of 35 male and 9 female military high school students (m=23, 1 years). On the basis of initial maximal performances in bench press the participants was divided into two experiments groups and one control group. Intervention groups performed a specifically designed push up program on a vibrating plate respectively a step board during 12 weeks</p><p> </p><p>Initial load at 60 % of 1 RM showed an average of 46, 5 kg. All groups showed an average increase of 13 kg for each person after 12 weeks. Initial value for power output showed a mean of 265 watt, which also showed an increase with an average of 7 watt (with a load equivalent of 60 % of 1 RM at the current test occasion), respectively an increase of 41 watt (with the load performed during the first test occasion). A positive correlation existed between the load at 60 % of 1 RM and achieved power output. No significant differences between groups were exposed concerning estimated maximum strength or power output in bench press. </p><p>All participants showed an increase in strength development, indicating that vibration stimuli could be compared to traditional push ups training without vibrations. Vibrations seem to have more effects on the magnitude of recruited motor units, why vibrations training could be a good complement to established strength training.</p><p>Abstract 2. </p><p>The purpose of this study was to investigate the effects whole body vibrations on strength development, power output and neuromuscular activity in m. pectoralis major during bench press. The purpose was also to examine what roll self-efficacy plays in strength tasks. </p><p>Participants consisted of 35 male and 9 female military high school students (m=23, 1 years). On the basis of initial maximal performances in bench press the participants was divided into two experiments groups and one control group. Intervention groups performed a specifically designed push up program on a vibrating plate respectively a step board during 12 weeks. All participants answered a battery of questionnaires concerning backgrounds, motives for sport participation, self-efficacy and efficacy sources. </p><p>Initial load at 60 % of 1 RM showed an average of 46, 5 kg (sd = 13, 8). All groups showed an average increase of 13 kg for each person after 12 weeks. Initial value for power output showed a mean of 265 watt, which also showed an increase with an average of 7 watt (with a load equivalent of 60 % of 1 RM at the current test occasion), respectively an increase of 41 watt (with the load performed during the first test occasion). A positive correlation existed between the load at 60 % of 1 RM and achieved power output. No significant differences between groups were exposed concerning estimated maximum strength or power output in bench press. Gender differences showed that men lifted significantly heavier loads at 60 % of 1RM compared to women. </p><p>No significant differences could be seen between the groups concerning self efficacy. Gender differences were exposed concerning self-efficacy to push ups with a pat. The efficacy sources “performance accomplishments” was valuated to be the most influential to form self-efficacy expectations. A strong positive relationship between “performance accomplishments” and achieved self-efficacy to push ups with pats were shown. Self-efficacy to push ups with a pat also correlated positively with power output and performed 60 % of 1 RM in bench press. </p><p>All participants showed an increase in strength development, indicating that vibration stimuli could be compared to traditional push ups training without vibrations. Vibrations seem to have more effects on the magnitude of recruited motor units, why vibrations training could be a good complement to established strength training. Participants relatively high self-efficacy to strength tasks is probably a result of performance accomplishments in there own strength straining rather than the intervention training. Positive relationships between self-efficacy and power output as well as performed 60 % of 1 RM in bench press, indicating that high self-efficacy have a positive influence on strength performance. </p><p>Keywords: estimated maximal strength (1RM), neuromuscular activity, power output, self-efficacy.</p>

Abstract 1. The purpose of this study was to investigate the effects whole body vibrations on maximal strength, power output and neuromuscular activity in m. pectoralis major during bench press. Participants consisted of 35 male and 9 female military high school students (m=23, 1 years). On the basis of initial maximal performances in bench press the participants was divided into two experiments groups and one control group. Intervention groups performed a specifically designed push up program on a vibrating plate respectively a step board during 12 weeks Initial load at 60 % of 1 RM showed an average of 46, 5 kg. All groups showed an average increase of 13 kg for each person after 12 weeks. Initial value for power output showed a mean of 265 watt, which also showed an increase with an average of 7 watt (with a load equivalent of 60 % of 1 RM at the current test occasion), respectively an increase of 41 watt (with the load performed during the first test occasion). A positive correlation existed between the load at 60 % of 1 RM and achieved power output. No significant differences between groups were exposed concerning estimated maximum strength or power output in bench press. All participants showed an increase in strength development, indicating that vibration stimuli could be compared to traditional push ups training without vibrations. Vibrations seem to have more effects on the magnitude of recruited motor units, why vibrations training could be a good complement to established strength training. Abstract 2. The purpose of this study was to investigate the effects whole body vibrations on strength development, power output and neuromuscular activity in m. pectoralis major during bench press. The purpose was also to examine what roll self-efficacy plays in strength tasks. Participants consisted of 35 male and 9 female military high school students (m=23, 1 years). On the basis of initial maximal performances in bench press the participants was divided into two experiments groups and one control group. Intervention groups performed a specifically designed push up program on a vibrating plate respectively a step board during 12 weeks. All participants answered a battery of questionnaires concerning backgrounds, motives for sport participation, self-efficacy and efficacy sources. Initial load at 60 % of 1 RM showed an average of 46, 5 kg (sd = 13, 8). All groups showed an average increase of 13 kg for each person after 12 weeks. Initial value for power output showed a mean of 265 watt, which also showed an increase with an average of 7 watt (with a load equivalent of 60 % of 1 RM at the current test occasion), respectively an increase of 41 watt (with the load performed during the first test occasion). A positive correlation existed between the load at 60 % of 1 RM and achieved power output. No significant differences between groups were exposed concerning estimated maximum strength or power output in bench press. Gender differences showed that men lifted significantly heavier loads at 60 % of 1RM compared to women. No significant differences could be seen between the groups concerning self efficacy. Gender differences were exposed concerning self-efficacy to push ups with a pat. The efficacy sources “performance accomplishments” was valuated to be the most influential to form self-efficacy expectations. A strong positive relationship between “performance accomplishments” and achieved self-efficacy to push ups with pats were shown. Self-efficacy to push ups with a pat also correlated positively with power output and performed 60 % of 1 RM in bench press. All participants showed an increase in strength development, indicating that vibration stimuli could be compared to traditional push ups training without vibrations. Vibrations seem to have more effects on the magnitude of recruited motor units, why vibrations training could be a good complement to established strength training. Participants relatively high self-efficacy to strength tasks is probably a result of performance accomplishments in there own strength straining rather than the intervention training. Positive relationships between self-efficacy and power output as well as performed 60 % of 1 RM in bench press, indicating that high self-efficacy have a positive influence on strength performance. Keywords: estimated maximal strength (1RM), neuromuscular activity, power output, self-efficacy.