Why are my arms still skinny?!

You seem confused about which muscles are trained by each exercise.

Chin ups DON'T work your arms. Doing good chinups, with each arm or both arms, means that you have a very strong BACK. (Pullups are even better; you pull the bar down to the middle of your chest, rather than your chin)

Pressups don't work your arms, either. Putting your hands close together will make you use a bit of tricep force to assist the movement, but it is still mainly a CHEST exercise.

You CAN target tricep with a similar exercise, usually called a 'plank lever'. But it is only related to the pressup by the way your 'middle position' looks.

Start in a 'plank support' position: like a pressup position, but with your elbows on the ground below your shoulders. You can put your hands in several different positions; most people prefer the 'sphinx' position, with your forearms parallel. From there, you straighten your arms so that your body rises, pause before your elbows lock out, and lower yourself to the starting position.

Your arms are probably strong enough to do this easily already; if not, then you can adapt the exercise by bringing your elbows 'down' your body, so that your upper arm isn't vertical. Push yourself up just like doing a pressup, and as you get used to the exercise you can use less and less upper-arm movement.

(If you are used to 'triangle' pressups, try starting in the 'up' position, but keep your elbows low while your body descends, instead of letting them move out and up)

You can use a waist-high pullup bar to work your bicep, in a similar way. Lying under the bar, keep your body straight while you try to get your elbows as high above the bar as possible. (This will only work with an 'under-grip', so that the arm movement is like bicep curls).

Spring-grips don't really work your fore-arm effectively, either. Try a wrist-roller as well (and make sure the weight is heavy enough to challenge you properly).

You could also try a hammer-bell; this is a dumbell handle with discs on one end only. You hold it in front of you (as if you are in the middle of a Bicep Curl) and 'flip' the weighted end from one side of your hand to the other, by turning your hand from palm-up to palm-down. You should flip the weight over your hand for some sets, and perform other sets where the weighted end flips UNDER your hand; this action is normally much more challenging.

Your type of training enhances the stamina of your muscles rather than the strength (which will make your muscles grow). Instead of 100 push ups for example, try 10 with one arm. So the repetitions should be a lot less, and the weight should be a lot more.

Besides, some people tend to get bigger muscles more easily than others. I also fitness, and I beat a lot of people with weights, even though other people seem bigger.

You need to focus on mass building exercises. Your current exercises are built for endurance, stamina. By the sound of it you will make a good rock climber. What you need to is move to mass building exercise. And nothing beats working with free weights and working your muscles to "failure". Than you will also have to supplement your diet with added protein to help the muscle build/recovery. Get advice from a fitness professional. Who will write you a program catering to your need. They will explain everything to you. Also research on the net on mass building training exercises.

that's because your building speed not strength. for example look at rock climbers or the people that ride in the tour de France. they are all in shape but skinny. its because you use low weight and many reps. if you you want to build muscle you need to use high weight and low reps. use the biggest weights you can and do three sets of 10, 8, 6, you should be using weight heavy enough so that you cant finish your last reps

work out

Follow geberdt's answer and also make sure you give your muscles lots of rest aswell as training since muscles don't grow through constant healing, they need rest to heal bigger and stronger ;) hope this helps (:

Steroids... ;D

It's great that your so aware of your form, good sign. I think it's a combination of things, the first being your form, when you say - chin ups fully extended- that tells me your relaxing the arm just a little too much, keep the strain on the muscle through out the movement.

How many days a week do you do arms ? is this all one routine, repeated ? That could be another reason, if your not givng the muscle time to recover from the previous workout, it won't growth will be hindered. Your doing to many reps, 8-12 should be your max, more reps for warm ups, less for the real work. ( focus on correct form on every exercise, don't just throw the weight around, keep the muscle feeling the weight on it at every point, from the beginning of the first rep, until you finish the last).

How long have you been at this ? It takes time to build muscle, and I have a feeling your expecting too much, too soon. Lastly don't forget to do legs. Whole body strength Have the whole system on prime for getting primmed! Eat decent, get to bed early, and take full two days off, but most important of anything, KEEP IT ENJOYABLE! It will totally pay off, just takes time and learning.