title: Validation of a method to measure total spontaneous physical activity of sedentary and voluntary running mice.
abstract: BACKGROUND
  Running wheels are commonly used to stimulate physical activity of mice. To control the effects of physical activity on study results, it is important to measure the total activity (all movements) of both sedentary and running wheel stimulated mice.
  
  
  METHODS
  Because there was a lack of a validated system, we built a force-plate based system specifically for this purpose. The validity of the system and its variables (activity index, activity time and distance) were tested in calibration measurements and in situ by measuring the activity of eight mice both with and without running wheels. Four mice served as sedentary controls. Activity index adds changes in vertical reaction forces induced by moving mice. The system records simultaneously all the activity, thus the wheel running is not distinguished from other activity.
  
  
  RESULTS
  There were very strong associations between measured activity variables and their true values (R(2)=1, p<0.01). The mean differences to true values were: activity index -9.7% (95% limits of agreement (LOA), -28.7 to 9.4%), activity time +0.9% (LOA, -1.3 to 3.0%) and distance +0.7% (LOA, -4.7 to 6.1%). The running wheels increased activity index 211 ± 40% (mean ± SE), activity time 39 ± 3% and activity intensity 94 ± 16%. Activity index (R(2)=0.982, p<0.01), activity time (R(2)=0.618, p<0.01) and intensity (R(2)=0.920, p<0.01) were positively associated with running distance.
  
  
  METHODS
  To our knowledge, this is the first method properly validated for this purpose.
  
  
  CONCLUSIONS
  The system is valid for the quantitation of total physical activity of mice housed in cages with or without running wheels.
authors: Neuromuscular Research Center, Department of Biology of Physical Activity, University of Jyväskylä, Finland. Electronic address: mika.silvennoinen@sport.jyu.fi.
authors: M
authors: M
authors: Silvennoinen
authors: Department of Health Sciences, University of Jyväskylä, Finland; Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Australia.
authors: T
authors: T
authors: Rantalainen
authors: Neuromuscular Research Center, Department of Biology of Physical Activity, University of Jyväskylä, Finland.
authors: H
authors: H
authors: Kainulainen
mesh_terms: D056044:Actigraphy / Q000295:instrumentation* / Q000379:methods*; D000818:Animals; D002138:Calibration; D004867:Equipment Design; D006799:Housing, Animal; D008297:Male; D008810:Mice, Inbred C57BL; D009043:Motor Activity; D012420:Running; D013997:Time Factors; D014836:Volition
keywords: Activity index; Activity time; Behavior; Distance; Force plate; Intensity