oldmansurfer wrote: For endurance you need to get winded during exercise. If you just exercise for a long time it doesn't help that much unless you are getting (slightly) out of breath. You need cardiovascular conditioning to be in shape.
Exactly right. Doing low intensity resistance exercise for a long time simply builds up lactic acid in the muscle until your muscle is tired. But it doesnt make the muscle stronger and it doesnt make your cardio system stronger. So there are no benefits (exception: you are an elite athlete regularly competing with very high lactic acid levels and want to build up a greater tolerance).
You would be much better off just doing bodyweight exercises (eg push ups, skipping, pull ups if you can, body weight squats, single leg squats, planks/variations. Etc, there are lots of them). Where these are hard (eg pull ups or maybe push ups) then they are good strength exercises; if you can do 15 or 20 reps (eg body squat, skipping) then you need to do them quickly so you are a bit out of breath. So if you have a 4kg weight, you could do really quick shoulder presses followed by bicep curls I guess, then repeat 6-8 times. Not that this is a particularly useful thing to do, I'm just not sure what else you can do with a 4kg dumbell!
So remember: to get any benefit you must either stress the muscle through weight (eg your max effort results in no more than 12 or so reps before you can do no more - so this is strength training, although within the rep range there are different variations depending on what you are exactly training for) or do it at a speed/rate that makes you breath hard (this is endurance). You can combine at times (boot camp or cross fit or circuit training style, or google 'escalating density training') but sitting in front of the TV with a 4kg weight is not one of those times!
There is a lot of evidence that endurance plus strength training is ideal for endurance athletes - not just endurance training alone (for strength athletes they dont need endurance so dont need to train).
So, dont get the 4kg dumbbell.
I feel your surfing pain. I had a bad session on the weekend and I'm still in a bad mood.