Table 2b: Characteristics of included studies investigating electrical Pain.

Study Study Participants [Sample size (M/F; age)] Classification of Obesity Noxious Stimuli Outcome Measure Data Obese
[Mean+SD]
Data Non-Obese
[Mean+SD]
Difference
P value
Authors’ Conclusion Methodological Quality Score (%)

Reviewers’ Comment
Zahorska-Markiewicz et al. (1983) [25] N = 48(0/48; 16-52 years)
N obese = 20 (0/20)
N non-obese = 20 (0/20)
N underweight = 8(0/8)
Percentage excess against ideal body weight from Metropolitan Life Insurance Tables
Mean % excess obese = 87.9%, non-obese = 1.6% and underweight = -10.1%
Transcutaneous electrical stimulation of forearm with amplitude increasing from 0-18mA Pain Threshold Forearm = 13.03+3.27mA
Arm = 8.83+4.31mA
Forearm = 7.55+3.76mA
Arm = 5.56+2.32mA

Forearm [underweight] = 5.88+3.18mA
Arm [underweight] = 6.1+5.34mA
Forearm <0.001
Arm P=<0.01
Obese less sensitive to noxious stimuli than non-obese 32%
Positive correlation between pain threshold and body weight, and weight excess
Zahorska-Markiewicz et al. (1988) [26] N = 49(0/49; 24-61 years)
N obese = 35(0/35)
N non-obese = 14(0/14)
Percentage excess against ideal body weight from Metropolitan Life Insurance Tables
Mean % excess obese = 64.5%, non-obese = not reported
Transcutaneous electrical stimulation of forearm with amplitude increasing from 0-20mAmin-1
at various time points throughout the day and over a 4 week weight reducing treatment phase
Pain Threshold [1st measure taken at 7am pre-treatment] 12.5+4.4mA 7.3+3.8mA <0.001 Obese less sensitive to noxious stimuli than non-obese 36%
Main focus of study was to investigate relationship between circadian rhythms and electrical pain threshold during weight-reducing treatment
Maffiuletti et al. (2011) [28] N = 67
(34/33)
N obese = 32(M/F not reported)
N ‘non-obese’ =35(M/F not reported)
BMI
Obese >30kg/m2
Transcutaneous electrical stimulation of quadriceps muscle to elicit muscle contraction Pain Intensity (100mm VAS) of ‘highest tolerated threshold’ to elicit contraction M=46+27mm
F=56+26mm
M=43+26mm
F=48+27mm
Not significantly different” [P value not reported] No difference in sensitivity to noxious stimuli between obese and non-obese individuals 66%
Conclusion “Current tolerance to motor stimulation was reduced in obese individuals … whereas pain was not influenced by gender or obesity

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