title: Is Borg's perceived exertion scale a useful indicator of muscular and cardiovascular load in blue-collar workers with lifting tasks? A cross-sectional workplace study.
abstract: OBJECTIVE
  To investigate associations between perceived exertion and objectively assessed muscular and cardiovascular load during a full working day among workers with manual lifting tasks.
  
  
  METHODS
  A total of 159 men and 41 women from 14 workplaces with manual lifting tasks participated. Participants reported perceived exertion (BORG-CR10) at midday and after work. Surface electromyography of the thigh, lower back and neck muscles were normalized to isometric voluntary contractions (MVC) to express relative muscle load during the day. Cardiovascular load was measured with electrocardiography and calculated as the average percentage of the heart rate reserve capacity (((heart rate during work - resting heart rate) / (maximum heart rate - resting heart rate)) * 100) during the day.
  
  
  RESULTS
  Using linear regression, significant but weak associations (β < 0.23) were observed between perceived exertion and (1) high muscle activity (>60% of MVC) of the neck muscles and (2) inactivity (<1% of MVC) of the thigh muscles and (3) cardiovascular load, respectively. Using logistic regression, perceived exertion ≥4 (high exertion), referencing <4 (low-to-moderate exertion), was related to high activity of the trapezius muscle [OR 18 (95% CI 2-143)], i.e., the odds for experiencing high exertion during work increased 18-fold for each percentage increase in time above 60% MVC.
  
  
  CONCLUSIONS
  During a full working day among blue-collar workers with lifting tasks, high neck muscle activity increases the odds for experiencing high perceived physical exertion. Perceived exertion of at least 4 on the BORG CR10 scale appears to be a good indicator that high muscular loading occurs.
authors: National Research Centre for the Working Environment, Lersø Parkalle 105, 2100, Copenhagen, Denmark, markusdue@gmail.com.
authors: Markus Due
authors: MD
authors: Jakobsen
authors: Emil
authors: E
authors: Sundstrup
authors: Roger
authors: R
authors: Persson
authors: Christoffer H
authors: CH
authors: Andersen
authors: Lars L
authors: LL
authors: Andersen
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006339:Heart Rate; D006801:Humans; D007221:Industry; D007537:Isometric Contraction; D017770:Lifting / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology* / Q000503:physiopathology; D063806:Myalgia / Q000503:physiopathology; D010147:Pain Measurement / Q000379:methods*; D010465:Perception; D005082:Physical Exertion; D017132:Workplace