photo @ Clarissa Freeman
In my opinion, just plain vanilla motorpacing (sitting behind the motor for 15-60 minutes at a time going hard) really provides an extremely "bursty" or variable power workout, at a high overall intensity.
What I believe this workout is best for is simulating the demands of a very hard race situation (think of hanging on in the draft by the skin of your teeth), for people who otherwise have no access to such types of workouts. I'm thinking high level racers for whom the "local group ride" just isn't hard/fast enough to push them. It's also good for people with limited access to racing, who are preparing for a "target" mass-start event. So you won't find a ton of guys in Tucson or San Diego doing it, but pros based in the midwest, or cyclo-cross riders in the Fall (when no one else is training hard) will commonly use it.
My experience is that the adaptation from steady power to the same overall intensity (i.e. - Intensity Factor) at variable power (for mass start racing specificity) is a fairly quick one - like a couple of sessions and you've got it. It is a nice "finishing touch" when preparing for fast, bursty events though.
From a Quadrant Analysis perspective, motorpacing is giving you more time than usual at high force/high cadence (Quadrant I). This type of work is tough to come by without actually racing or motorpacing.
You can also structure the workouts a little more. On the track it's an excellent way for endurance riders to simulate a points race, complete with sprints around the motor. Road sprinters seem to like the "sprinting around the motor" workout on the road, which I think is primarily a neuromuscular specificity thing...How else are they going to start their sprint and come out of a draft at 55-60kph without a motor?
I've done TTT training behind a motor, I think it's usefulness for TT and TTT training is somewhat more limited now that we have powermeters and can see what's really going on. You can make an argument that pacing with a scooter or small motorbike is good for TTT riders in skills practice, but who rides TTTs anymore?
In the old days, we would assume we were getting a "better" workout, because it's quite easy to see high HR for extended periods with the combination of variable power, high intensity, and the excitement/adrenaline of training 10-15kph faster while focusing on staying in the draft (and not putting too many vertical stripes on the bumper of your girlfriend's car).
© JBV Coaching 2006