Re: Does the lung capacity vary between boys and girl?

Hi Jonathan - This is a good question.  The factors that dictate the 
capacity of the lungs (called vital capacity) are, gender, age and height. 
 There is a sort of graph called a nomogram on which you plot your height 
and age after selecting the nomogram for your gender and it will indicate 
your normal vital capacity.  At your age, the differences will be quite 
small since the heights of boys and girls before puberty is not very large. 
 For adults, the nomogram works pretty well.  Vital capacity can be 
directly measured on an instrument called a spirometer.  There are several 
types but the one we use at my college is a "wet" one.  The person takes 
several deep breaths and then blows as hard as he/she can into the machine 
(it has a hose attached to it) and then you read the number of liters of 
vital capacity right off of the spirometer.  As to your question about 
swimming, that is a very aerobic activity and will definately increase a 
person's lung capacity.  I have a competitive swimmer in my class this 
semester and out of 20 students, she was the only one who exceeded her 
predicted vital capacity as determined by her nomogram.  Any aerobic 
activity, if done over a long period of time, will increase V.C.  Smoking, 
asthma, allergies, being a "couch potato", etc. will hinder lung function. 
 I hope this answers your question.  J. Bridger