Travel time has generally been regarded as an unproductive period, representing a means-to-an-end in order to engage in activities at specific destinations. Rapid developments in mobile technology have provided people with innovative ways to multi-task and engage in meaningful activities while travelling. Rail transportation specifically, offers passengers advantages over other means of transportation as there is no need to focus on driving tasks. Due to the increase in passenger numbers and limited seating availability in train carriages, over one third of rail passengers are required to stand while travelling (DfT, 2013). The vibration to which rail passengers are exposed has been shown to interfere with the performance of activities and for standing passengers, it is often necessary to use postural supports such as holding on to grab rails or leaning on walls in order to maintain stability. The overall aim of the research is to evaluate the influence of whole-body vibration (WBV) exposure and standing posture on the performance of manual control tasks and the associated subjective workloads experienced by rail passengers. The use of supports, such as a backrest in seated postures, has been found to influence the response of the human body to WBV exposure, yet no reported studies have investigated the effects of postural supports on the response of the body in standing postures. Understanding how the body is affected in these conditions would increase the current state of knowledge on the biomechanical responses of the human body to vibration exposure and provide improved representation of standing postures within vibration standards (for example, ISO2631-4 (2001)) and guidelines for device interface design. A field study, using direct observation, was conducted to assess the behaviour of standing rail passengers and determine the characteristics of typical vibration exposures. This information provided the basis for the design of four subsequent laboratory studies. The main investigations of the laboratory studies were the influence of WBV exposure on objective performance measures, such as task completion time and error rate, and subjective workloads (for example, NASA TLX) for a range of manual control tasks. One of these laboratory studies evaluated the influence of various postural supports (for example, backrests) on the biomechanical responses of standing individuals. Measurements obtained during the field investigation indicated that the vibration exposures did not exceed the EU Physical Agents Exposure Action Value (EAV) and therefore posed little risk of injury. Vibration magnitudes in the horizontal directions (x- and y-axes) were higher than in the vertical direction (z-axis) and it was necessary for standing passengers to alter behaviours and use supports in order to maintain stability while travelling. The results of the laboratory studies indicated that in conditions where decrements in task performance occurred, the extent to which performance was degraded increased progressively with increases in vibration magnitude. There were conditions (for example, in the continuous control task and the Overhead Handle supported posture in the serial control task) where vibration exposure showed no significant influence on performance measures. This suggested that individuals were able to adapt and compensate for the added stress of vibration exposure in order to maintain performance levels however, this occurred at the expense of mental workload. The workload experienced by the participants increased with corresponding increases in magnitude. Vibration frequency-dependent effects in performance and workload were found to match the biomechanical responses (apparent mass and transmissibility) of the human body and resemble the frequency weightings described in the standards (ISO2631-1 (1997)). During the serial control task, the postures which demonstrated the greatest decrements to performance (for example, Lean Shoulder and Lean Back ) corresponded to the same postures that showed the greatest influence on the biomechanical responses of the body. It was concluded therefore, that measurements of the biomechanical responses to WBV could be used to offer predictions for the likelihood of activity interference. Consideration should however, be given to the applicability of this research before these results can be generalised to wider contexts. Further validation is recommended for future work to include different conditions in order to substantiate the findings of this research.

Whole-body vibration (WBV) was recently introduced as a potential modality for strengthening bones, and this thesis was set out to investigate whether it plays a role in the prevention of postmenopausal bone loss. First, effects of WBV on bone mineral density (BMD) were systematically evaluated in previous randomized controlled trials (RCTs) in postmenopausal women. Second, a RCT of 202 postmenopausal women with primary osteopenia not on bone medications was conducted to investigate the effects of WBV at 0.3g and 90 Hz versus 0.3g and 30 Hz versus controls on various bone outcomes, as measured by dual-energy x-ray absorptiometry (DXA), high-resolution peripheral quantitative computed tomography (HR-pQCT), and quantitative ultrasound (QUS). In the systematic evaluation of previous RCTs, statistically significant increase in areal BMD (aBMD) at the hip was found in postmenopausal women receiving WBV versus controls, but the effect was small and may have been due to study bias. Also, WBV was not found to influence aBMD at the lumbar spine or volumetric BMD (vBMD) at the distal tibia in the systematic evaluation. In the RCT conducted in this thesis, no statistically significant effects of WBV were found on aBMD at the femoral neck, total hip or lumbar spine, as measured by DXA, or on vBMD or bone structure parameters at the distal tibia or distal radius, as measured by HR-pQCT. Further in this RCT, a statistically significant decrease was observed in QUS attenuation at the calcaneus in women receiving 90 Hz or 30 Hz WBV compared to controls. This may have been due to heel bone or soft tissue damage, although the effect was small and may not be clinically important. In conclusion, this investigation of postmenopausal women did not find clinically relevant benefits of WBV on osteoporotic-prone skeletal sites, including the hip, spine, tibia or radius, while potentially harmful effects on heel bone and/or soft tissue was observed in response to WBV. Thus based on this thesis, WBV is currently not recommended for the prevention of bone loss in community-dwelling postmenopausal women with primary osteopenia.

In this study the exposure of mining vehicle operators, on an opencast goldmine in Tanzania, to certain hazards specific to their occupation was assessed. The aim was to quantify these levels of exposure in order to estimate the risk of health effects but also to report levels of these hazards that exist on mining vehicles. Three different hazards with different physiological effects were assessed and it included exposure to whole-body vibration, A-weighted noise and low frequency noise. In each case correctly calibrated instrumentation was used and internationally accepted methods were followed. It was found that mining vehicles commonly exposed operators to levels of whole-body vibration within and above the ISO Health Guidance Caution Zone (HGCZ) and above the ropean action level, which indicates the need for intervention and control. These levels are a cause for concern and will likely lead to health effects. Noise that damages human hearing (A-weighted noise) was present in high levels on mining vehicles, in each case being higher than the permissible exposure limit of 85 dB(A). Thus operators of mining vehicles are exposed to noise levels that will damage their hearing in time. A potential hazard in the occupational world, low frequency noise, was also included in the assessment. Literature indicates that low frequency noise is capable of causing many human health effects and thus levels on mining vehicles were reported in order to give an indication of what levels may be expected in this department of mining. It was found that much of the sound energy measured on vehicles was located in the low frequency range. In the lowest frequency band measured, Leq levels of more than 100 dB(Z) were commonly found. Controls should be implemented as far as is reasonably practicable to ensure that operators are not exposed above recommended or permissible levels for each hazard. These controls can include good maintenance of vehicles and roads to reduce whole-body vibration, sound proofing of vehicle cabs along with hearing protection devices to protect hearing and further research regarding the exposure and health effects caused by low frequency noise. Following literature indicating the physiological effects of low frequency noise exposure and also the presence thereof in different occupations, it is concluded that A-weighted noise measurements alone can not be used when quantifying the risk involved in a given acoustical environment. / Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2009

In this study the exposure of mining vehicle operators, on an opencast goldmine in Tanzania, to certain hazards specific to their occupation was assessed. The aim was to quantify these levels of exposure in order to estimate the risk of health effects but also to report levels of these hazards that exist on mining vehicles. Three different hazards with different physiological effects were assessed and it included exposure to whole-body vibration, A-weighted noise and low frequency noise. In each case correctly calibrated instrumentation was used and internationally accepted methods were followed. It was found that mining vehicles commonly exposed operators to levels of whole-body vibration within and above the ISO Health Guidance Caution Zone (HGCZ) and above the ropean action level, which indicates the need for intervention and control. These levels are a cause for concern and will likely lead to health effects. Noise that damages human hearing (A-weighted noise) was present in high levels on mining vehicles, in each case being higher than the permissible exposure limit of 85 dB(A). Thus operators of mining vehicles are exposed to noise levels that will damage their hearing in time. A potential hazard in the occupational world, low frequency noise, was also included in the assessment. Literature indicates that low frequency noise is capable of causing many human health effects and thus levels on mining vehicles were reported in order to give an indication of what levels may be expected in this department of mining. It was found that much of the sound energy measured on vehicles was located in the low frequency range. In the lowest frequency band measured, Leq levels of more than 100 dB(Z) were commonly found. Controls should be implemented as far as is reasonably practicable to ensure that operators are not exposed above recommended or permissible levels for each hazard. These controls can include good maintenance of vehicles and roads to reduce whole-body vibration, sound proofing of vehicle cabs along with hearing protection devices to protect hearing and further research regarding the exposure and health effects caused by low frequency noise. Following literature indicating the physiological effects of low frequency noise exposure and also the presence thereof in different occupations, it is concluded that A-weighted noise measurements alone can not be used when quantifying the risk involved in a given acoustical environment. / Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2009

Whole-body vibration (WBV) was recently introduced as a potential modality for strengthening bones, and this thesis was set out to investigate whether it plays a role in the prevention of postmenopausal bone loss. First, effects of WBV on bone mineral density (BMD) were systematically evaluated in previous randomized controlled trials (RCTs) in postmenopausal women. Second, a RCT of 202 postmenopausal women with primary osteopenia not on bone medications was conducted to investigate the effects of WBV at 0.3g and 90 Hz versus 0.3g and 30 Hz versus controls on various bone outcomes, as measured by dual-energy x-ray absorptiometry (DXA), high-resolution peripheral quantitative computed tomography (HR-pQCT), and quantitative ultrasound (QUS). In the systematic evaluation of previous RCTs, statistically significant increase in areal BMD (aBMD) at the hip was found in postmenopausal women receiving WBV versus controls, but the effect was small and may have been due to study bias. Also, WBV was not found to influence aBMD at the lumbar spine or volumetric BMD (vBMD) at the distal tibia in the systematic evaluation. In the RCT conducted in this thesis, no statistically significant effects of WBV were found on aBMD at the femoral neck, total hip or lumbar spine, as measured by DXA, or on vBMD or bone structure parameters at the distal tibia or distal radius, as measured by HR-pQCT. Further in this RCT, a statistically significant decrease was observed in QUS attenuation at the calcaneus in women receiving 90 Hz or 30 Hz WBV compared to controls. This may have been due to heel bone or soft tissue damage, although the effect was small and may not be clinically important. In conclusion, this investigation of postmenopausal women did not find clinically relevant benefits of WBV on osteoporotic-prone skeletal sites, including the hip, spine, tibia or radius, while potentially harmful effects on heel bone and/or soft tissue was observed in response to WBV. Thus based on this thesis, WBV is currently not recommended for the prevention of bone loss in community-dwelling postmenopausal women with primary osteopenia.

Limited research has been conducted on inconsistencies relating to whole-body vibration (WBV) field assessments. Therefore, this study aimed to investigate a certain possible contributor to inconsistencies in vibration assessment work, namely averaging intervals. To our knowledge, this was the first study investigating the effect of multiple averaging approaches on WBV results. WBV parameters were measured for a driver operating a vehicle on a preselected test route utilising ISO 2631-1:1997. This was achieved utilizing a Quest HavPro vibration monitor with a fitted tri-axial Integrated Circuit Piezoelectric (ICP) accelerometer pad mounted on the driver’s seat. Furthermore, in an attempt to decrease differences between observed WBV results, an outlier detection method, part of the STATA software package was utilised to clean the data. Statistical analyses included hypothesis testing in the form of one-way ANOVA and Kruskal-Wallis one-way analysis of variance by ranks to determine significant differences between integration intervals. Logged data time-series durations showed a W0 = 0.04, therefore indicating unequal variance. Omission of 60s from statistical analyses showed a W0 = 0.28. The observed difference occurs when data is averaged over longer intervals, resulting in portions of data not being reflected in the final dataset. In addition, frequency-weighted root mean squared acceleration results reflected significant differences between 1s, 10s, 30s, 60s and SLOW averaging approaches, while non-significant differences were observed for crest factors and instantaneous peak accelerations. Vibration Dose Value results reflected non-significant differences after omission of 60 second averaging interval data. Cleaned data showed significant differences between various averaging approaches as well as significant differences when compared with raw vibration data. The study therefore outlined certain inconsistencies pertaining to the selection of multiple integration intervals during the assessment of WBV exposure. Data filtering could not provide a conclusion on a suitable averaging period and as such, further research is required to determine the correct averaging interval to be used for WBV assessment. / Dissertation (MPH)--University of Pretoria, 2014. / tm2015 / School of Health Systems and Public Health (SHSPH) / MPH / Unrestricted

Vibrations are often experienced in the workplace and may influence performance and executive function. Research has shown that vibrations may have an affect effect on drowsiness and tests related to inhibitory control. Previous work investigating whole body vibrations (WBV) and their effect was evaluated to inform the decisions for this study. WBV effects on cognitive abilities were examined and the different tests used in these studies were identified and compared. Electroencephalogram (EEG) and event related potentials (ERP) were selected to be used to measure inhibitory and cognitive processes. The N2 ERP, which reflects inhibitory control processes, was examined as well as the dominant frequency of the Fourier fast transform (FFT). A total of 94 participants between the ages of 18-55 (Mage = 20.49 SDage = 1.68) completed this study (51 female, 38 male and 5 with no gender listed). A go/no-go task was used to elicit the N2 ERP after WBV and a simultaneous EEG recording while the participants experienced WBV was used to gather the needed data. Stimulus frequencies used for the N2 ERP included 15 Hz, 20 Hz, and 40 Hz. During the simultaneous recording stimulus frequency varied every 30 seconds by 10 Hz from 20 Hz to 110 Hz. Data were analyzed using both a linear mixed effects model for normally distributed data and a generalized linear mixed effects model for data taken as percentages. It was hypothesized that there would be an effect on performance as measured in the raw go/no-go results, that this change in performance showing improved accuracy would be linked to inhibitory control, and be seen as a decrease in the magnitude of the N2 ERP. It was also hypothesized that the exploratory FFT portion of the study would produce a shift from a higher to a lower frequency in the dominant waveform . The results show that there were no main effects in either the behavioral performance or in the N2 ERP of the participants but that there was a significant interaction at 40 Hz with improved simple go trial activity and decreased no-go inhibition. The results also show that there was a statistically significant shift in neural oscillation activity but that this shift was not real-world relevant within the context of this study.

Introduction: Very few studies have looked at the effect of vibration on flexibility, and no studies exist that have looked at stretching concurrently with whole body vibration (WBV) training. Therefore, the purpose of this study was to determine if whole-body-vibration training (WBV) done concurrently with static stretch (SV) is more effective than static stretching alone (SS), and to see if WBV training independently (SQ) improves hamstring flexibility without stretching. A secondary purpose of this study is to determine if retention of flexibility gains are maintained. Methods: Forty-four subjects (31 men, 13 women) completed this study (age 22.5 ± 1.8 years; body mass 75.54 ± 13.18 kg; height 176.7 ± 8.06 kg). All subjects were randomly assigned to 1 of 5 groups: SV group (8 males, 3 females), SQ group (8 m, 4 f), SS group (8 m, 3 f), and the C group (7 m, 3 f). All subjects were measured bilaterally for hamstring flexibility using the lying passive knee extension test (LPKE) prior to group assignment. Subjects from each treatment group reported to lab 5 times per week for treatment. Subjects stood on the WBV platform for 5 repetitions of 30-seconds at with 30-seconds in between bouts. The SV group stretched hamstrings while standing on the WBV during the vibration bouts (at 26 Hz and 4 mm amplitude). The SS group did the same thing except the unit was not turned on. The SQ group stood on the WBV platform in a semi-squat position similar to most WBV training studies, without stretching, but with vibration. The C group stood on the WBV platform in a semi-squat without vibration. Analysis and Results: A mixed models analysis of covariance (ANCOVA) was used while blocking on subjects to analyze data using the statistical program SAS (version 9.1). A Bonferroni correction was used for significance on all post hoc tests (p<.0001). At baseline there were no significant differences between groups for flexibility (see Table 1), showing that each group was similar in flexibility to start. Throughout the treatment period (3 weeks of stretching) both the SS and SV groups had significant increases in flexibility compared to SQ and C. Analysis of the slopes (rate of change) for the treatment period was significantly different between the SV group and all other groups (p<.0001 for all comparisons), showing that the SV group had a greater rate of change than all other groups. For the retention period there was no significant difference between the SV and SS group (p=0.0455), but there was a significant difference between both the SV and SS groups and all other groups (p<.0001 for all comparisons). Conclusion: Stretching during WBV improves flexibility more than static stretching alone and at a faster rate. WBV on its own without stretching does not significantly improve hamstring flexibility.

The purpose of this study was to determine if whole body vibration effects strength gains in the bench press, the back squat, and the power clean in division 1 football players. Thirty-one NCAA Division 1 male football players volunteered for this study and were randomly assigned to a control group (C=16) or one of two vibration groups (V1=7, V2=8). Subjects followed the training program for eight weeks. A pre-test, mid-test, and post-test one repetition max was measured at 0, 4, and 8 weeks for the bench press, the back squat, and the power clean. A 3x3 factorial ANOVA revealed varied results between the three lifts performed. In the bench press, there were no significant differences in strength gains between the three training groups (F=.616, p=.547). In addition, there was no significant interaction (F=1.05, p=3.74). There were significant differences between trials in the bench press in strength gains (F=7.570, p=.006). In the back squat, there were no significant differences in strength gains between the three training groups (F=.847, p=.440). In addition, there were no significant differences in interaction (F=1.734, p=1.83). There were significant differences between trials in the back squat in strength gains (F=17.111, p<.001). In the power clean, there were no significant differences in strength gains between the three training groups (F=.666, p=.522). In addition, there were no significant differences in interaction (F=.113, p=.912). There were significant differences between trials in the power clean in strength gains (F2=26.249, p<.001). While all groups registered significant strength gains over trials, there were no significant differences in strength gains between any of the three treatment groups or any of the three dependant variables. It was concluded that whole body vibration does not enhance strength gains in division I football players.

BACKGROUND: Whole body vibration (WBV) platforms are currently used as adjunctive training devices for exercise programs, and have been shown to facilitate flexibility. One of the biggest contributing factors to chronic ankle instability (CAI) is the lack of dorsiflexion after lateral ankle sprains and WBV may be an effective way to increase range of motion in this population. PURPOSE: Determine if WBV done concurrently with static stretching (SS) is more effective then SS alone in improving dorsiflexion ROM in subjects with CAI. METHODS: Subjects were divided into 3 groups (control, static stretch, and static stretch and vibrate). Subjects stretched 4 days/wk for 3 wks for 4 sets of 30 seconds alternating 2 different positions to stretch both the soleus and the gastrocnemius. Imposed vibration at 34 Hz 2mm during the stretches for the stretch group. ANALYSIS: Repeated measures ANOVA was performed using SPSS (version 19), with post-hoc Tukey tests as needed (p<.05). RESULTS: In both the straight and bent leg position, a significant group x time interaction was found for dorsiflexion range of motion. Post hoc tests revealed significance in the SV group between pre-tx and post-tx 1 and pre-tx and post-tx 2. No statistical significance was found between post-tx 1 and post-tx 2 in the SV group or at any time in the N or SS group. DISCUSSION: Static Stretching with vibration increases dorsiflexion ROM in subjects with CAI better than static stretching alone.