How do you define walking vs jogging?
 

Instead of doing my usual 4 mph walk on the treadmill, I was able to bump it up to 4.8 mph - and was definitely moving in a "jogging" mode (i.e., not having one foot on the ground at all times.).

According to the Weight Watchers descriptions, going between 3 - 5 mph on the treadmill is considered "brisk walking." However, this level of activity definitely puts my heart rate WAY up high (90% of max) with a high perceived level of exertion. Would it be fair of me to log this activity as jogging?

I started out at 4.8 for my "runs" and yes I counted them. It was totally different than like a 4.0 walk and my heart rate increased a lot. I would most definately call it jogging!

i would log it as jogging. its a slow jog, but i know when i first start off i use to do a slow job at about 4.8. i can't imagine walking at 4.8..i'd fall off the treadmill LOL

4.8 is definitely a jog for me too..

jogging is by definition when you are not having 1 foot on the ground. Pace is irrelevant to the definition. Log it as jogging

Race walkers can walk faster than I can run...its about the gait, not the speed.

FWIW
From a calorie burn perspective Runnersworld did a study and found that until about 11 minute miles running burns more calories than walking at identical paces (i.e. running at 4.8 burns more than walking at 4.8) faster than 11 minute miles the weird ergonomics of speedwalking take over. (who can walk an 11 minute mile?...I would fall over too!)

I wouldn't trust any site that simply gives a number without regard to height, etc. I used to use the treadmill next to another girl who was nearly 6'. What she could WALK, I had to jog. My legs were much much shorter than hers and I didn't have nearly the span between my steps that she had. It's just like the height/weight charts that allow for frame sizes. You have to take into account the differences in people for the number to be of any value.

Looks like most of us that replied are about the same height-
For me, I can walk up to 4.4 mph. 4.5-4.6 are just uncomfortable and I can't really find a gait that works. 4.8 is a slow jog for me, but with the length of my legs, walking isn't really possible.

As ennay said, it's all about the gait, not the speed.

Mel