When to increase the weights?

[Sanitarium]

I've been using 4kg (bout 10lbs) dumbbells for a few weeks and although feel heavy, I'm not sure whether it's heavy enough. I mean I could probably do about 50 curls in one go without too much trouble. And about 25 punches with the same hand. Reckon I should increase to 5/6/10kg ones? Money is an issue so I don't wanna buy ones I'll 'grow out of' in a few weeks/months. I was thinking of maybe getting 8kg ones, using them for strength training, and the 4kg ones for endurance and toning.

[Strepto]

It all depends of what your goals are... If you want to build muscle and strength put enough weight so you can do a set of 8-10 reps. When you can do 10 reps with the weight it's time to add some more... not much, just enough to be able to do a set of 8 reps max. Then keep this weight until a few days or weeks later when you can do sets of 10 reps with that weight... then add some more to de 8 reps max.... go on until you hit the 10 reps limit. That's the best way to go.
For endurance and toning... i don't know...

[Sanitarium]

Ahh. I've heard about the 8-10 thing before, thanks. I can do wayyy more than 10 so...I think I'll go to about 8kg (18lbs)

[shadowkiller]

One thing, dont punch with weights. Its never a good idea.

[Sanitarium]

No? I don't do it as hard as to strain my muscles or stretch too far, I do punches in a safe range. Lol, the first time I tried it, I threw a hard punch and hurt my arm near the shoulder, that taught me. I realised it wasn't a good idea to punch with 4kg sailing along aswell as my fist. But with care, I thought it'd be a good way to exercise the muscles involved in jabbing, and the tops of shoulders/forearms too. You know...if you punch with extra weight, and then take the weight away, you'll be faster and harder. Same kind of idea behind jumping onto crates with weights round your ankle to improve jumping power.