Börje Rehn

Effects on leg muscular performance from whole-body vibration exercise : a systematic review.

The purpose of this study was to investigate the effects on leg muscular performance from whole‐body vibration exercise. Literature search was performed on the databases Pubmed, Cinahl, ISI web of science (Sci‐expanded, SSCI) and Embase (Rehab & Physical Med). Rating of 19 relevant studies was performed (14 on long‐term exercise and five on short‐term exercise) using a score system for the methodological quality. Several randomized‐controlled trial studies of high to moderate quality show similar improvements from long‐term regimen on muscular performance in the legs after a period of whole‐body vibration exercise. As there were few studies on short‐term exercise and as they had no control groups, the same convincing improvements regarding muscular performance were not achieved. Preliminarily, there is strong to moderate evidence that long‐term whole‐body vibration exercise can have positive effects on the leg muscular performance among untrained people and elderly women. There is no clear evidence for effects on muscular performance after short‐term vibration stimuli.

Neuromusculoskeletal disorders in the neck and upper extremities among drivers of all-terrain vehicles – a case series

BackgroundThe purpose of this study was to investigate whether professional drivers of all-terrain vehicles (ATVs) with neck pain have a different array of neuromusculoskeletal disorders in the neck and upper extremities than a referent group with neck pain from the general population. It is hypothesized that exposure to shock-type vibration and unfavorable working postures in ATVs have the capacity to cause peripheral nervous lesions.MethodsThis study was based on a case series analyzed according to a case-case comparison design. The study population consisted of 60 male subjects, including professional drivers of forest machines (n = 15), snowmobiles (n = 15), snowgroomers (n = 15) and referents from the general population (n = 15) all of whom had reported neck pain in a questionnaire and underwent an extensive physical examination of the neck and upper extremities. Based on symptom history, symptoms and signs, and in some cases chemical, electroneurographical and radiological findings, subjects were classified as having a nociceptive or neuropathic disorder or a mix of these types.ResultsThe occurrence of asymmetrical and focal neuropathies (peripheral nervous lesion), pure or in a mix with a nociceptive disorder was common among cases in the ATV driver groups (47%–79%). This contrasted with the referents that were less often classified as having asymmetrical and focal neuropathy (27%), but instead had more nociceptive disorders. The difference was most pronounced among drivers of snowgroomers, while drivers of forest machines were more frequently classified as having a nociceptive disorder originating in the muscles.ConclusionThis study found a high prevalence of assymetrical and focal neuropathies among drivers with pain in the neck, operating various ATVs. It seems as if exposure to shock-type whole-body vibration (WBV) and appurtenant unfavorable postures in ATVs may be associated to peripheral nervous lesions.

All-terrain vehicle use in agriculture: Exposure to whole body vibration and mechanical shock

Whole body vibration (WBV) and mechanical shock were measured in 12 New Zealand farmers during their daily use of all-terrain vehicles (ATVs). As per the International Organization for Standardization (ISO) guidelines for WBV exposure, frequencies between 0 and 100Hz were recorded via a seat-pad tri-axial accelerometer during 20min of ATV use. The farmers were also surveyed to estimate seasonal variation in daily ATV usage as well as 7-day and 12-month prevalence of spinal pain. Frequency-weighted vibration exposure and total riding time were calculated to determine the daily vibration dose value (VDV). The daily VDV of 16.6m/s(1.75) was in excess of the 9.1m/s(1.75) action limit set by ISO guidelines suggesting an increased risk of low back injury from such exposure. However, the mean shock factor R, representing cumulative adverse health effects, was 0.31 indicating that these farmers were not exposed to excessive doses of mechanical shock. Extrapolation of daily VDV data to estimated seasonal variations of farmers in ATV riding time demonstrated that all participants would exceed the ISO recommended maximum permissible limits during the spring lambing season, as compared to lower exposures calculated for summer, autumn and winter. Low back pain was the most commonly reported complaint for both 7 day (50%) and 12 month prevalence (67%), followed by the neck (17% and 42%) and the upper back (17% and 25%) respectively. The results demonstrate high levels of vibration exposure within New Zealand farmers and practical recommendations are needed to reduce their exposure to WBV.

Does Daily Exposure to Whole-Body Vibration and Mechanical Shock Relate to the Prevalence of Low Back and Neck Pain in a Rural Workforce?

OBJECTIVES To determine whether whole-body vibration (WBV) and mechanical shock exposure from quad bike use are associated with the prevalence of neck and low back pain (LBP) in New Zealand farmers and rural workers. METHODS Full-day WBV and mechanical shock exposures were gathered from 130 farmers and rural workers. Participants were surveyed for a history of neck or LBP in the past 7 days and in the past 12 months. Anthropometric, personal, and workplace data were also gathered. RESULTS Physical exposures (mechanical shocks), employee status, and low levels of workplace satisfaction are all significantly associated with the 12-month prevalence of LBP in this rural workforce that regularly use quad bikes. Both vibration and mechanical shock exposure were strongly associated with 12-month prevalence of neck pain. The 7-day prevalence of neck pain showed a non-significant association with mechanical shock and vibration. CONCLUSIONS Knowledge of these findings will be valuable information for those who teach and advise on safe driving techniques for such vehicles in the rural workplace where reduction of physical exposures and injury rates is of high importance.

Adolescents with intellectual disability have reduced postural balance and muscle performance in trunk and lower limbs compared to peers without intellectual disability.

For adolescent people with ID, falls are more common compared to peers without ID. However, postural balance among this group is not thoroughly investigated. The aim of this study was to compare balance and muscle performance among adolescents aged between 16 and 20 years with a mild to moderate intellectual disability (ID) to age-matched adolescents without ID. A secondary purpose was to investigate the influence of vision, strength, height and Body Mass Index (BMI) on balance. A group of 100 adolescents with ID and a control group of 155 adolescents without ID were investigated with five balance tests and three strength tests: timed up and go test, one leg stance, dynamic one leg stance, modified functional reach test, force platform test, counter movement jump, sit-ups, and Biering-Sørensen trunk extensor endurance test. The results showed that adolescents with an ID in general had significantly lower scores in the balance and muscle performance tests. The group with ID did not have a more visually dominated postural control compared to the group without ID. Height, BMI or muscle performance had no strong correlations with balance performance. It appears as if measures to improve balance and strength are required already at a young age for people with an ID.

Exposure to Whole-Body Vibration and Mechanical Shock: A Field Study of Quad Bike Use in Agriculture

OBJECTIVES The purpose of this study was to determine exposure to whole-body vibration (WBV) and mechanical shock in rural workers who use quad bikes and to explore how personal, physical, and workplace characteristics influence exposure. METHODS A seat pad mounted triaxial accelerometer and data logger recorded full workday vibration and shock data from 130 New Zealand rural workers. Personal, physical, and workplace characteristics were gathered using a modified version of the Whole Body Vibration Health Surveillance Questionnaire. WBVs and mechanical shocks were analysed in accordance with the International Standardization for Organization (ISO 2631-1 and ISO 2631-5) standards and are presented as vibration dose value (VDV) and mechanical shock (S(ed)) exposures. RESULTS VDV(Z) consistently exceeded European Union (Guide to good practice on whole body vibration. Directive 2002/44/EC on minimum health and safety, European Commission Directorate General Employment, Social Affairs and Equal Opportunities. 2006) guideline exposure action thresholds with some workers exceeding exposure limit thresholds. Exposure to mechanical shock was also evident. Increasing age had the strongest (negative) association with vibration and shock exposure with body mass index (BMI) having a similar but weaker effect. Age, daily driving duration, dairy farming, and use of two rear shock absorbers created the strongest multivariate model explaining 33% of variance in VDV(Z). Only age and dairy farming combined to explain 17% of the variance for daily mechanical shock. Twelve-month prevalence for low back pain was highest at 57.7% and lowest for upper back pain (13.8%). CONCLUSIONS Personal (age and BMI), physical (shock absorbers and velocity), and workplace characteristics (driving duration and dairy farming) suggest that a mix of engineered workplace and behavioural interventions is required to reduce this level of exposure to vibration and shock.

Neck pain combined with arm pain among professional drivers of forest machines and the association with whole-body vibration exposure

The purpose of this study was to investigate the existence of neck pain and arm pain among professional forest machine drivers and to find out if pain were related to their whole-body vibration (WBV) exposure. A self-administered questionnaire was sent to 529 forest machine drivers in northern Sweden and the response was 63%. Two pain groups were formed; 1) neck pain; 2) neck pain combined with arm pain. From WBV exposure data (recent measurements made according to ISO 2631–1, available information from reports) and from the self-administered questionnaire, 14 various WBV exposure/dose measures were calculated for each driver. The prevalence of neck pain reported both for the previous 12 months and for the previous 7 d was 34% and more than half of them reported neck pain combined with pain in one or both arms. Analysis showed no significant association between neck pain and high WBV exposure; however, cases with neck pain more often experienced shocks and jolts in the vehicle as uncomfortable. There was no significant association between the 14 WBV measures and type of neck pain (neck pain vs. neck pain combined with arm pain). It seems as if characteristics of WBV exposure can explain neither existence nor the type of neck pain amongst professional drivers of forest machines. The logging industry is important for several industrialised countries. Drivers of forest machines frequently report neuromusculoskeletal pain from the neck. The type of neck pain is important for the decision of treatment modality and may be associated with exposure characteristics at work.

Test-retest reliability, smallest real difference and concurrent validity of six different balance tests on young people with mild to moderate intellectual disability

OBJECTIVES Some studies have reported that people with intellectual disability may have reduced balance ability compared with the population in general. However, none of these studies involved adolescents, and the reliability and validity of balance tests in this population are not known. The purpose of this study was to examine the reliability of six different balance tests and to investigate their concurrent validity. DESIGN Test-retest reliability assessment. SETTINGS All subjects were recruited from a special school for people with intellectual disability in Bollnäs, Sweden. PARTICIPANTS Eighty-nine adolescents (35 females and 54 males) with mild to moderate intellectual disability with a mean age of 18 years (range 16 to 20 years). INTERVENTIONS All subjects followed the same test protocol on two occasions within an 11-day period. MAIN OUTCOMES Balance test performances. RESULTS Intraclass correlation coefficients greater than 0.80 were achieved for four of the balance tests: Extended Timed Up and Go Test, Modified Functional Reach Test, One-leg Stance Test and Force Platform Test. The smallest real differences ranged from 12% to 40%; less than 20% is considered to be low. Concurrent validity among these balance tests varied between no and low correlation. CONCLUSION The results indicate that these tests could be used to evaluate changes in balance ability over time in people with mild to moderate intellectual disability. The low concurrent validity illustrates the importance of knowing more about the influence of various sensory subsystems that are significant for balance among adolescents with intellectual disability.

Validity and reliability of the Dynamic One Leg Stance (DOLS) in people with vision loss

This study tests the concurrent validity and test–retest reliability of a new functional balance test – the Dynamic One Leg Stance (DOLS) in blind subjects and sighted, blindfolded subjects. Twelve blind and 12 sighted men and women between 19 and 61 years volunteered to participate. The correlation between DOLS and the commonly used One Leg Stance balance test (OLS) and the force platform test (FPT) was tested for both the right and left leg. The test–retest reliability of DOLS was analysed using three measurements at least 2 h apart. The correlation between DOLS and FPT and between DOLS and OLS for blind subjects was −0.13 (n.s.) and 0.77 for the left leg and −0.78 and 0.89 for the right leg. For blindfolded subjects, the correlations were −0.56 (n.s.) and 0.93 for the left leg and −0.61 and 0.71 for the right leg. The weighted Kappa values for DOLS were between 0.47 and 0.88 for blind subjects and between 0.47 and 0.72 for blindfolded subjects. Based on these findings, DOLS appears to be a fairly valid and reliable balance test for subjects with vision loss, acquired and experimental. However, further tests of DOLS are necessary.

Effects of whole-body vibration exercise on human bone density – systematic review

Abstract Objectives: The effects of whole-body vibration exercise (WBVE) on human bone density are systematically reviewed. Methods: Several databases, PubMed, Cinahl, Embase and Pedro were searched and papers graded according to the Pedro scale. The grey literature was also evaluated and added to the review. Two independent reviewers evaluated the quality of the studies and evidence for an effect. Results: Eight of the nine included studies showed positive effects for WBVE on bone density in the lower half of the body particularly in post-menopausal women. Discussion/Conclusion: Because the overall strength of evidence was considered moderate, several clinical questions still need to be addressed. Existing studies, however, suggest that WBVE may be a promising training modality.