Ideally the 'pump' is not for your biceps, but shoulders. The book is really nice, he goes into the details of how it's to be done.

Ok, so I just did 4.1 miles on the treadmill at 8% uphill slope with 5-pound weights in each hand. I'm sure it works the shoulders as well, but there is definitely some bicep work going on there -- you have to keep your elbows bent, for one thing, which means your biceps must be doing some work.

I'm still at 1 kg, brisk walk, 2 hours straight. Will go to 2.5 kgs soon.

Its great you were able to walk with a 2.5 kgs on the very first try.

I think I'm going to go up to 3-pound weights. It definitely feels like a more complete workout.

It feels far more tiring than a regular jog, or a run.

The higher weights will be even better. It feels so obvious now that we see this, but it follows from common sense, with four limbs and weights the workload is far higher than a regular walk/jog/run.

There is no sense in going to back to regular plain weightless hand walk/run/jogs.