A study on the difference of human sensation evaluation to whole-body vibration in sitting and lying postures

Effects of body orientation and direction of movement on a knee joint angle reproduction test in healthy subjects: An experimental study

BACKGROUND

Joint position sense test assess patient mobility and proprioceptive ability. Yet, application used under different conditions may biases reproduction error resulting in different therapeutic consequences.

OBJECTIVE

To investigate knee angle reproduction test under different test conditions.

METHODS

25 healthy subjects (mean ± SD, age = 25 ± 2 years, activity level: 9 ± 2 training hours/week) performed knee angle reproduction test in the sitting and prone position, while changing the knee angle starting (i) from flexion and (ii) extension, (iii) inducing vibration on the semitendinosus tendon.

RESULTS

Absolute mean knee angle reproduction error showed significant difference for body position and vibration (Position: 95% CI 0.71 to 2.32; p< 0.001. No Vibration & Vibration: 95% CI -1.71 to -0.12; p= 0.027). Relative knee angle reproduction error was significant different in all conditions (No Vibration & Vibration: 95% CI -3.30 to -0.45; p= 0.010. Body orientation: 95% CI 1.08 to 3.93; p< 0.001. Direction of movement: 95% CI 0.56 to 3.41; p= 0.007).

CONCLUSION

Body orientation and movement direction influence the resulting knee angle reproduction error in healthy subjects. Practitioners are advised to use standardised test procedures when comparing different within- and between-patient results.

TRIAL REGISTRATION

DOI 10.17605/OSF.IO/AFWRP.

An investigation of a cluster of cervical herniated discs among container truck drivers with occupational exposure to whole-body vibration

OBJECTIVE

This study aimed to determine if occupational exposure to whole-body vibration is associated with cervical intervertebral disc herniation among container truck drivers.

METHODS

We conducted a walk-through survey among container truck drivers and unexposed workers. We also measured the vibration hazard of the container truck over the driver's back and seat when the driver was loading a container and driving the loaded truck.

RESULTS AND DISCUSSION

Among the 38 workers interviewed, 32 were container truck drivers. Four of them reported cervical herniated discs, and all of these individuals were container truck drivers with a job tenure of greater than 10 years. Self-reported cervical herniated disc, nuchal pain, nocturia, arm/forearm weakness, arm/forearm numbness, and finger numbness were significantly more prevalent as the driver's duration of exposure increased (all p values of test for trend <0.05). The vibration of the truck during and after loading a container was considered the main cause of herniated disc. When a container truck was driven with a loaded container, both the vertical and horizontal vibrating acceleration over the seat and back sites exceeded the 8-hr exposure level based on the ISO 2631-1 criteria. The transient vibration dose values (VDVs) measured during misaligned or unsmooth loading operations were usually greater than the upper bounds of the health guidance caution zone for the 8-hr VDV.

CONCLUSIONS

Our investigation disclosed a cluster of cervical intervertebral disc herniation that was associated with the vibration hazard during long-term container truck driving under full load and possibly aggravated by misaligned loading operations.