title: Hand and finger dexterity as a function of skin temperature, EMG, and ambient condition.
abstract: OBJECTIVE
  This article examines the changes in skin temperature (finger, hand, forearm), manual performance (hand dexterity and strength), and forearm surface electromyograph (EMG) through 40-min, 11 degrees C water cooling followed by 15-min, 34 degrees C water rewarming; additionally, it explores the relationship between dexterity and the factors of skin temperature, EMG, and ambient condition.
  
  
  BACKGROUND
  Hand exposure in cold conditions is unavoidable and significantly affects manual performance.
  
  
  METHODS
  Two tasks requiring gross and fine dexterity were designed, namely, nut loosening and pin insertion, respectively. The nested-factorial design includes factors of gender, participant (nested within gender), immersion duration, muscle type (for EMG), and location (for skin temperature). The responses are changes in dexterity, skin temperature, normalized amplitude of EMG, and grip strength. Finally, factor analysis and stepwise regression are used to explore factors affecting hand and finger dexterity.
  
  
  RESULTS
  Dexterity, EMG, and skin temperature fell with prolonged cooling, but the EMG of the flexor digitorum superficialis remained almost unchanged during the nut loosening task. All responses but the forearm skin temperature recovered to the baseline level at the end of rewarming. The three factors extracted by factor analysis are termed skin temperature, ambient condition, and EMG. They explain approximately two thirds of the variation of the linear models for both dexterities, and the factor of skin temperature is the most influential.
  
  
  CONCLUSIONS
  Sustained cooling and warming significantly decreases and increases finger, hand, and forearm skin temperature. Dexterity, strength, and EMG are positively correlated to skin temperature. Therefore, keeping the finger, hand, and forearm warm is important to maintaining hand performance.
  
  
  CONCLUSIONS
  The findings could be helpful to building safety guidelines for working in cold environments.
authors.affiliation: Department of Industrial Management, National Taiwan University of Science and Technology, Taipei, Taiwan.
authors.forename: Wen-Lin
authors.initials: WL
authors.lastname: Chen
authors.forename: Yuh-Chuan
authors.initials: YC
authors.lastname: Shih
authors.forename: Chia-Fen
authors.initials: CF
authors.lastname: Chi
mesh_terms: D000328:Adult; D003080:Cold Temperature / Q000009:adverse effects*; D004576:Electromyography; D005163:Factor Analysis, Statistical; D005260:Female; D005385:Fingers; D006225:Hand; D018737:Hand Strength; D006801:Humans; D007101:Immersion; D016014:Linear Models; D008297:Male; D009048:Motor Skills; D012881:Skin Temperature; D013647:Task Performance and Analysis