Chronic Adaptations to Spinal Flexion Exposure

Study Overview
=================
Brief Summary
-----------------
An experimental study, which will aim to compare changes of trunk mechanical properties and neuromuscular control following spinal flexion exposure in crane operators and control subjects.

Detailed Description
-----------------
Our experimental study will include 40 participants, more specifically 15 crane operators and 15 control subjects. All participants will complete a 60-min protocol of intermittent trunk flexion. Measurements of trunk mechanical properties and neuromuscular control will be performed prior to and following the 60-min protocol.

Official Title
-----------------
Chronic Adaptations to Spinal Flexion Exposure in Crane Operators

Conditions
-----------------
Occupational Exposure

Intervention / Treatment
-----------------
* Other: Repeated trunk flexion


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Crane operators: employed as crane operators for more than 3 years Occupational workers with a predominantly non static job (e.g. combination of sitting and standing) Exclusion Criteria: History of chronic low back pain Episode of acute low back pain Hip injury in the past six months Previous spine, pelvis or hip surgery Hypermobility, diagnosed with the Beighton score High intensity resistance training (> 75 % of 1 repetition maximum) more than two times a week Control group: sporting or recreational activities, that include repetitive spinal flexion or maintenance of a flexed posture (for example cycling or rowing).

Ages Eligible for Study
-----------------
Minimum Age: 30 Years
Maximum Age: 55 Years

Sexes Eligible for Study
-----------------
Male

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Basic Science
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Crane operators<br>Individuals employed as crane operators in Port of Koper. | Other: Repeated trunk flexion<br>* A 60-min intermittent trunk flexion protocol. Participants will sit on a standard height sit, with their knees bent at approximately 90° with their hands crossed on their chest. They will perform 40 sets of 60 s of maintaining a flexed position, interspersed with 30 s of rest. Participants will achieve the flexed position by tilting the pelvis posteriorly and leaning forward. During rest, participants will sit up straight without leaning on the support.<br>|
| Active Comparator: Control subjects<br>Individuals who spend more than half of their occupation time standing. | Other: Repeated trunk flexion<br>* A 60-min intermittent trunk flexion protocol. Participants will sit on a standard height sit, with their knees bent at approximately 90° with their hands crossed on their chest. They will perform 40 sets of 60 s of maintaining a flexed position, interspersed with 30 s of rest. Participants will achieve the flexed position by tilting the pelvis posteriorly and leaning forward. During rest, participants will sit up straight without leaning on the support.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in muscle stiffness | Muscle stiffness will be measured using ultrasound-based shear wave elastography during prone lying and forward stooping. Erector spinae and multifidus muscle stiffness will be expressed as the shear modulus value in kilopascals. | 90 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in range of motion | Trunk flexion range of motion will be evaluated using Spinal Mouse in maximal trunk flexion while standing. | 90 minutes | 
| Change in length of the spine | The length of spine will be measured on a custom-developed stadiometer, with the participants in a seated position. | 90 minutes | 
| Change in muscle activity | Muscle activity will be measured using electromyography during standing, a forward stoop hold and during maximal trunk flexion. | 90 minutes | 
| Change in lumbar lordosis angle | The lumbar lordosis angle will be evaluated using Spinal Mouse during upright standing. | 90 minutes | 
| Change in trunk extension maximal strength | Isometric trunk extension peak torque will be assessed on a trunk dynamometer. | 90 minutes |