6. With energy source, the aerobic contribution were similar, and it appeared that most of the difference was due to a higher anaerobic contribution in HH. This suggests that, when racing, you're better able to tap into a central physiological reserve because your brain is willing to let your body work harder.
Race to Train
One way of doing intervals is to replicate what was done in this study. Find a like-minded partner and do intervals together in a head-to-head setting, and put something on the line (e.g. who buys the coffee). If your abilities are dissimilar, you can have an over-under time cut and do a handicap race that way.
A team time trial, a smoothly rotating paceline, or a group ride where each rider takes a long steady pull are all good ways of incorporating group efforts on the road that'll provide solid training and minimal mental effort compared to doing it solo.
If you're actually in a race and using to train, have a clear plan for what you want to accomplish. Your goals can range from getting a long, hard ride in the pack, working on positioning or pre-planning an attack from the peloton.
More: 5 Ways to Win Friends on a Group Ride
Remember, racing is going to be a much harder training stress than going solo. Make sure that you plan your recovery and your periodization around it properly.
Offseason Competition
I've been taking some of this competitive spirit to heart over this offseason. My buddy Rob and I, both about equal in ability as Masters racers, set up a training cave down in my basement complete with big-screen projectors and all sorts of high-tech toys.
We trained together every day, with the advantage that we keep each other accountable and motivated for indoor workouts. And even though our size and FTPs are different, there remains the subtle and not-so-subtle battle of "what wattage did you do that last interval at?" to push each other with.
More: 10 Rules to Group Ride Like a Pro
We've also been successfully sprinkling in virtual races in with Tour de Giro to give us that mental carrot of competition without having to think about intervals.
These are just a few ideas. Come up with something on your own to keep things interesting. With today's technology, you never have to train alone unless you want to.
Summary
Above all, even if you never intend to enter a competitive event, group rides can be great training and great fun, so join the peloton every once in awhile.
More: Basic Skills for Group Riding
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