Hello

I am trying to increase strength in my arms.

Does it matter if I only get one adjustable dumbell and alternate between arm during excercise?

Or would it be more beneficial to my goal for me to purchase two dumbbells (1 for each arm)?

Please let me know.

Thanks,
Randy

I would say 2, for convenience sake.

I like to do every exercise with 2 dumbbells simultaneously, and that has worked very well for me, to build up muscle in a balanced between both sides of body.

There are 2 major exceptions (for me at least) however.
One is bicep curls, the other is wrist curls. Both of them, I can't imagine doing with both arms at the same time, because it's just so much better individually.

Another advantage of 2 dumbbells is that you can do lower body exercises equally - with one dumbbell in each arm.

isn't there an actual train of thought to working out with one dumbell? Something that you get stronger because its an unbalanced load and your going to work your core muscles as well to balance yourself.

From what I understand, and I'm not a personal trainer, so be warned, but it's good to have two dumbells and do exercises that incorporate both at the same time as well as one dumbell at a time. Using one dumbell does force your core, plus other various stabilizers, to do more work, because of the balance issue. Any muscle or stabilizer that would be required to balance you during a one-dumbell exercise isn't going to get the same work during a two-dumbell move. Of course, if you only do one-dumbell moves, you could risk injuring yourself as well as missing out on benefits that come from two-dumbell workouts.
Hope this was helpful

For arms, i suggest you get a barbell and start doing barbell curls, they focus on the biceps and are essential for big strong arms. But to answere your question 2 dumbbells are much better and offer a greater variety of excerises.

If I were you, I'd go ahead and invest in a second dumbell, to add further variety and to save time when you need to. If you have the time, curling one dumbell at a time with strict form will challenge your core muscles as well. However, if you're going to maximally load on a really heavy set, you might want more stability so you can focus on those biceps more.

Oh yeah, and you'll probably find 2 dumbells more practical for most lower body exercises- and others as well.