To determine the influence of “thin”, “normal”, and “obesity” on the motor function and exercise capacity of chronic obstructive pulmonary disease (COPD) patients, as well as whether “obesity” is actually “harmful” for such patients. A total of 103 COPD patients in a stable condition were classified into three groups: a “thin group” (BMI<18.5), an “normal group” (18.5≤BMI<25), and an “obesity group” (BMI≥25). Fourteen patients from each group matched for %FEV_1.0, sex, and age were evaluated. The measurement items were: respiratory function, respiratory muscle strength, lower and upper limb muscle strength, the 30-sec chair-stand test (CS-30), timed up and go test (TUG), 6-minute walking test (6MWT), incremental shuttle walking test (ISWT), Nagasaki university respiratory questionnaire (NRADL), and St. George’s respiratory questionnaire (SGRQ). As a result of comparing the three groups, the %MIP was significantly higher in the obesity compared to thin group (p=0.04). No differences were seen between the groups in the mMRC, %MEP, quadriceps femoris muscle strength (%), CS-30, TUG, 6MWT, ISWT, NRSDL, and SGRQ, but these values showed a tendency to be favorable in the obesity group. The BMI was significantly and positively correlated with the %MIP and NRADL. It was suggested that management of the respiratory muscle strength, exercise tolerance, and ADL when COPD patients are obese rather than thin can be possibly associated with a higher QOL.

As regards obesity screening tests, it's a widly known fact that there are many problems in the existing notation of various body indices.
Moreover, in regards to the determination of skin-fold thickness, measurments must be taken at two or three places, and this, plus the fact that a certain amount of expertise is necessary, represent a shortcoming.
Using abdominal girth, which can be relatively easily measured, together with the chest girth measurment, the author examined a method for assessing obesity.
Various body indices were computed from height, weight, chest measurement, abdominal girth, etc. and the correlation between their value and skin fold thickness and average skin fold thickness was determined.
As a result of this, abdominal girth measurement and evaluation may be used in obesity screen tests in the following way.
1. Method for measuring abdominal girth.
[1] Have the patient assume normal posture.
[2] Girth is measured (in centimeters) around the area mid way above the navel while the patient resting expiratory state with arms hanging limp and shoulders relaxed.
2. Method for computing obesity index.
obesity index=height (in cm) ×10/abdominal girth (in cm)
The subject of the above research is extreamly limited in respect to age range. Therefore, the authors would like to examine further to see if this method is applicable to all age renges.