Trunk Muscle Strength, Strength Endurance and Activity in Persons With Low Back Pain
Condition: Low Back Pain
MeSH terms: Back Pain; Low Back Pain
Study type: Observational

Summary: 
      The research questions are if persons with low back pain (LBP) have lower trunk muscle
      strength, lower trunk muscle strength endurance and lower trunk muscle activity than healthy
      controls and if functional limitations because of LBP are related to the level of muscle
      strength, strength endurance and activity. To investigate this investigators will carry out a
      clinical assessment including questionnaires and a biomechanical assessment comprising muscle
      strength tests, muscle strength endurance tests and electromyographic (EMG) analysis of
      selected trunk muscles.
    

Detailed description: 
      Objectives

      The current state of research in the field and of the investigators own clinical experience
      clearly shows that the role of trunk muscle function in LBP is poorly understood.
      Investigators will address the following research questions:

        -  Do persons with LBP have lower trunk muscle strength, lower trunk muscle strength
           endurance and lower trunk muscle activity than healthy controls?

        -  Are functional limitations because of LBP related to the level of muscle strength,
           strength endurance and activity?

      To answer these questions, investigators will establish an experimental framework to study
      limitations in muscle function to address the following aims:

        -  To compare trunk muscle strength, strength endurance and activity between persons with
           LBP and healthy control persons.

        -  To determine the relationship between trunk muscle strength, strength endurance and
           activity, and the Oswestry Disability Index (ODI) score.

      The experimental setting consists of a clinical assessment using a questionnaire and a
      biomechanical assessment comprising muscle strength tests, muscle strength endurance tests
      and electromyographic analysis. Electromyographic activity of selected trunk muscles will be
      recorded during isokinetic and isometric trunk flexion and extension strength tests and
      during isometric trunk flexion and extension strength endurance tests.

      Hypotheses Investigators hypotheses are that i. persons with LBP have lower trunk muscle
      strength, strength endurance and activity than healthy controls subjects. ii. the intensity
      of the EMG signal in lower back muscles decreases faster during the strength endurance test
      in persons with LBP than in healthy control subjects. iii. clinical scores correlate with
      trunk muscle strength, strength endurance and activity.

      Procedures First, written informed consent will be obtained before participants will undergo
      a clinical exam (inspection and palpation of the lower back, measurement of active range of
      motion) performed by a trained physical therapist (PS). All participants will complete
      questionnaires to obtain pain and functional scores and information on their typical physical
      activity level (approximate duration: 30 minutes). Bipolar skin electrodes will be placed on
      selected trunk muscles (approximate duration: 15 minutes) and participants will walk on a
      treadmill for 10 min (warm-up). Participants will be seated on a strength testing system and
      practice trunk flexion and extension movements for 1 min. Subsequently, subjects will be
      asked to perform isokinetic trunk flexion and extension tests at maximum effort. EMG signals
      of the trunk muscles will be recorded during the maximum isokinetic contractions (approximate
      duration: 20 minutes). Subsequently, subjects will lie supine on a bench with their legs and
      pelvis supported by the bench. Their upper legs will be secured to the bench using a 15 cm
      wide Velcro belt. Subjects will be asked to hold their trunk in a horizontal position as long
      as possible while EMG signals of the trunk muscles will be recorded (approximate duration: 5
      minutes).
    

Intervention name(s): No intervention
Intervention type(s): Other
Intervention description(s): There is no intervention in this cross-sectional study
Observational model: Cohort
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        20 persons with LBP 20 age and sex matched healthy control persons
      
Keywords: electromyography, strength, strength endurance