My current cardio sessions follow this format: Warmup (50% Max Heart Rate), stretch (HR drops), elevate HR again, workout, cooldown, stretch again.

Unfortunately, my time is become more scare and I need to streamline my lengthy cardio sessions. To this end, I'm thinking of omitting the stretching prior to working out. Is it ok to do cardio without stretching beforehand? I have tried it a couple of times and found it rather unpleasant. However, I can cope with the discomfort if isn't going to do harm to my body in the long-run.

I stretch for a short period, no longer than 6 seconds on each muscle, mostly because my muscles are cold as soon as I wake up.
I do a huge amount of stretching but mostly at the end of a workout, when I'm knackered, my muscles are warmed up, and I want to impress the people in the gym :)

I always stretch before I do cardio, and I recommend it. I have tight hamstrings, and it makes my workouts a lot more pleasant when I stretch thoroughly (3 minutes total per stretch) beforehand. Otherwise, I tend to tighten up and experience pain around the 20 minute mark.

And when I do strain something that forces me to take a day or two off, it's almost always on a day I rushed the stretching.

It's just anecdotal evidence, but that's what you asked for, so I figure it's okay.

I aim for 65% max heart rate. This goal is achieved through low impact cardio. I am not really straining my muscle at all no matter what piece of equipment I use: treadmill, arc trainer, or eliptical.

Pretty much I never stretch.

I aim for 65% max heart rate. This goal is achieved through low impact cardio. I am not really straining my muscle at all no matter what piece of equipment I use: treadmill, arc trainer, or eliptical.

Pretty much I never stretch.

Are those arc trainers hard on the lower back?

If I'm running, I usually warm-up, stretch, and then start my cardio workout. When I'm not completely wiped out I will really stretch for flexibilty after a workout.

When swimming, I warm-up and, most often after 400 yards, I do various upper body stretches -- mostly for the shoulders and lats -- to help loosen up before another 600 yards or so of warm-up. I rarely stretch for flexibility after a workout.

I've been stretching for flexibility a lot more often though.

Chicanerous, when you say "stretch for flexibility" does that mean a special type of stretching?