and a typical couch potato, which would you expect to have a higher density of mitochondria? Why? What about a muscle biopsy from the biceps of a weight lifter?
consider what mitochondria do. Do they produce coffeine? No. Do they produce sugar? No. Do they produce ATP which is needed for muscle contraction?
What needs more energy, sitting on a couch or running a marathon?
Another factor to consider is if a lot of energy is needed fast or a moderate amount of energy is needed constantly. Marathon runners actually do not run all that fast compared with somebody who specializes in sprinting short distances. Sprinters get their energy from the lactic acid pathway as they need energy at a faster rate than the mitochondria can supply. This pathway is not in the mitochondria. A weight lifter is more like a sprinter. So now you should know that part of the question too.
I don’t know. However, when a muscle doubles in size from exercise, it does not double the number of muscle cells which remain relatively constant, except for repairs following certain injuries. This likely means that the ‘stronger’ muscle cells have need for more energy conversion and therefore need more mitochondria, which are the tiny power plants. Also, there are two types of leg muscle cells, fast and slow twitch, where great sprinters likely have a higher ratio of fast twitch muscle and marathon runners likely have a greater ration of slow muscle cells for endurance. Couch potatoes likely don’t twitch very much and have fat cells instead of muscle cells making up their bulk. Weight lifters likely need slow twitch muscles.
References :
http://sportsmedicine.about.com/od/anatomyandphysiology/a/MuscleFiberType.htm
http://www.purchon.com/biology/mitochondria.htm
consider what mitochondria do. Do they produce coffeine? No. Do they produce sugar? No. Do they produce ATP which is needed for muscle contraction?
What needs more energy, sitting on a couch or running a marathon?
Another factor to consider is if a lot of energy is needed fast or a moderate amount of energy is needed constantly. Marathon runners actually do not run all that fast compared with somebody who specializes in sprinting short distances. Sprinters get their energy from the lactic acid pathway as they need energy at a faster rate than the mitochondria can supply. This pathway is not in the mitochondria. A weight lifter is more like a sprinter. So now you should know that part of the question too.
References :