Enrico Marchetti

Forestry work in the Italians alps: metabolic demand assessed by heart rate

Objective : This research aims to: a) assess the energy expenditure during typical forestry activities; b) assess the actual workload of forestry work; c) define the eventual relationship between oxygen uptake ( ) and heart rate during the studied working phases. Methods : Eleven healthy skilled forestry workers were studied. Using a portable device, oxygen uptake ( ), carbon dioxide output ( ), pulmonary ventilation ( ) and heart rate (HR) were measured. The forestry work was divided into four phases: walking uphill, felling, limbing & chain-sawing and complementary activities. A work time report was kept and in each phase a weighted average (WA) of all parameters was obtained. Results :Walking uphill, felling, limbing & chain-sawing activities did not show significant statistical differences between each other and were classified as heavy activities (mean 2.17 lmin-1,mean HR 157 beatmin-1). The complementary activity was found to be less demanding and statistically differed in respect to the others ( 0.55 l min-1, HR 98 beat min-1). By theWA, the actual workload of forestry work resulted in a moderate to heavyoptimal job ( and HR being 1.51 l min-1 and 133.5 beat min-1 respectively in a typical working day). Furthermore it was possible to set up a relationship between and HR for the forestry work. Conclusions : Forestry activity can be classified as moderate to heavy-optimal. Finally, a good and linear correlation between and HR proved to be an easy tool to evaluate the metabolic demand.

87 Muscular activation in vibration perturbed human walking and modelling

Introduction Walking on vibrating floor causes a complex exposure pattern and the superimposition of walk and vibration may induce early muscular fatigue.1 The problem is relevant is many field, as sea platform or railway transports. The present study studies the leg muscular activation and stride phases during walking under vibration to derive a muscle model in these circumstances. Methods Subjects walked on a treadmill positioned on a 6-DOF vibrating table. Vibration was imposed at four frequencies (4, 8, 12, 16 Hz) along vertical and transversal direction. The walking speed was set at 1.25 m/s. Surface electromyography (sEMG) of four muscles was recorded. Stride phases were recorded using accelerometers and stride length was calculated. Acceleration signals were acquired in several body districts (foot, knee and hip). All measurements were related to the walking condition without the vibration. Result Preliminary results showed that vibration does not affect stride length and step phases. The muscular activation patterns exhibit frequency related modification, in terms of sEMG bursts amplitude and timing. There is a linear correlation between 8 Hz frequency and muscular activation. Discussion Transmitted vibration triggers a tonic vibration reflex (TVR) that is related to mechanical frequencies.2 TVR is also related to the motor task because of the mechanical coupling between vibrator and biological apparatus.3 These facts could explain the modifications in leg muscle activation revealed with sEMG. References . Fattorini L, Tirabasso A, Lunghi A, Di Giovanni R, Sacco F, Marchetti E. Muscular forearm activation in hand-grip tasks with superimposition of mechanical vibrations. J Electromyogr Kinesiol2016;26:143–148. . Eklund G, Hagbarth KE. Normal variability of tonic vibration reflexes in man. Exp Neurol1966;16:80–92. . Fattorini L, Tirabasso A, Lunghi A, Di Giovanni R, Sacco F, Marchetti E. Muscular synchronisation and hand-arm fatigue. Int J Ind Ergon2017.

1685f How does mechanical vibration reach the cochlea

Introduction Several epidemiological studies highlighted a synergistic interaction between noise and mechanical vibration exposure.1 The etiologic mechanism is still missing. Moreover, the measured transmissibility from the hand to the head seems to be poor. At the shoulder, frequency over 30 Hz are practically suppressed. If there are not any vibration left, how can mechanical energy interact with the cochlea? The aim of this speculation is to approach the transmission of vibration from entering point to the cochlea from a different point of view. Proposed methods In the seminar on hand-arm vibration exposure3 to isolated and repeated shock vibrations held in October 2015 in Beijing it was suggested that a wider spectral component of mechanical vibration may travel in the blood vessels and impair vasoregulation and nerve terminations in fingers. Such a suggestion may apply to transmission to even more far district, due to the fact that blood vessels can work as waveguide for pressure, because they are designed to be so. Methodology Can be summarised as following. Effects of vibrations on the hearing function will be assessed by stimulated otoacoustic emission method. Vibration elicitation will be strictly controlled (shaker and 6 DOF vibrating plate). Overall vibration will be measured by accelerometers on joints and head. Blood vessel vibration propagation will be measured by high resolution, dual frequency echography4,5 on main vessels (coronary) and small vessels. The frequency spectrum of hearing loss and blood vessels vibrations, deducted by the heart pumping effects, will be compared to look for coincidence. References . Sisto R, Botti T, Cerini L, Di Giovanni R, Marchetti E, Lunghi A, Sacco F, Sanjust F, Tirabasso A, Moleti A. Synergistic effects of noise and hand-arm vibration on distortion product otoacoustic emissions in healthy subjects. Int. J. Ind. Ergon2016:1–7. http://dx.doi.org/10.1016/j.ergon.2016.10.006 . Adewusi SA, Rakheja S, Marcotte P, Boutin J. Vibration transmissibility characteristics of the human hand–arm system under different postures, hand forces and excitation levels. Journal of Sound and Vibration2010;329:2953–2971. http://dx. doi:10.1016/j.jsv.2010.02.001 . IFA Report 5/2017e, DGUV, Hand-arm vibration: Exposure to isolated and repeated shock vibrations – Review of the International Expert Workshop2015 in Beijing. http://www.dguv.de/ifa/publikationen/reports-download/reports-2017/index-2.jsp . Papadopulou V, Balestra C, Theunissen S, Germonpré P, Obeid G, Boutros A, Dayton PA, Eckersley RJ, Cosgrove D, Tang MX. Can contrast mode echocardiography help estimate bubble population dynamics post-dive? EUBS 43rd annual scientific meeting, Ravenna, Italy, 12–16 September 2017. . Self-assessment of the jugular venous pulse from space and special environments – Paolo Zamboni, EUBS 43rd annual scientific meeting, Ravenna, Italy, 12–16 September 2017.