QUOTE(degraw1993 @ Apr 15 2015, 04:38 PM)
LOL i just make it simple. Can you build chest with just push ups? Yes you can but you're building more endurance it means eventually your body will adapt to it.
So in order to build muscle or hypertrophy you need to load up the weights that's when you stimulate the muscle.
Terima kasih for your explanation though simple one, i can finally understand why you say that. From your statement you assume that by doing push up you won't get progressive overload a because as you say your body will adapt to it. The principle of strength of course that to be stronger you need to apply more resistance which is what you implied, which is true. Before i take things further lets explore the concepts of strength:
Strength can be defined as the ability to create force to counter act/overwhelm an opposing force or resistance. Simple. So to have more strength you would need to increase either; Intesity, volume or frequency. That's the basic concept of it... so lets try an experiment:
Hold out your fist straight out in front of you at shoulder height and hold it there (the concept of equilibrium) . Not to hard is it, so let's apply the principle of Intensity, volume & frequency. Grab a light dumbell say 4kgs... nothing to hard and hold it back out in front of you. Obviously it'll harder to hold then before. This shows that by adding volume this gets harder, as you say progressive overload.
Let's try something else; with the same dumbell take out the weights of one side and put attach it to one end. So the dumbell will have both 2kg plates on one side of the dumb bell then hold the dumb bell by the empty side and lift it up shoulder length again, you'll notice that the intensity has changed even though you're still holding the same 4kg weights. What has happened is that the leverage for the dumb bell has changed making it harder hence more strength is needed.
Now because of the nature of body weight training, where the weight of the trainee remain fixed the only way to increase intensity is to... LEVERAGE ON YOUR BODY! So obviously working the same move will not provide an increase of strength, as you said. So how does one make things harder? By leveraging your body to make things harder hence a progression. (Also, did you know there are harder variations of the push up? For example; diamond push ups, uneven push ups...

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I would love to explain more but i'm running late... hope it helps.