The old adage “slow and steady wins the race” is half true. While no triathlete wants to be slow in the saddle, harnessing a steady pace has been shown, literally, to win the race. Along with cadence and heart rate, your power output, or wattage, plays an important role in nailing down your ideal pacing strategy.
One study out of England’s Loughborough University looked at this issue by collecting and analyzing 12 race power profiles from elite male triathletes in various international events. Backing up what many coaches and athletes already knew, they found that large variations in power make for a higher workload in the saddle than riding at constant power.
Another study had participants take two separate one-hour rides that both equaled a mean power of 65 percent. The first condition required riders to vary their power between 40 and 140 percent, and the other had them cycle at a steady pace. Following each bike workout, the researchers had the athletes run a 9.3K time trial, showing that they ran slower after varying their power output on the bike than when they rode at a constant speed. Simply put, regularly adjusting your effort is more metabolically costly than riding at an even pace, even if you finish in the same amount of time.
To determine the stability of your power output, you must look at the variability index (VI). When you learn to harness your power output on the bike, you ride right up to your limit without pushing so hard you are forced to back off in subsequent stages of a race.
“The more a triathlete ends up outside their comfort zone, the more likely they will suffer both on the bike and on the run,” explains John Bryan, a USA Triathlon and USA Cycling certified coach in Redondo Beach, Calif. “The longer the race, the fewer fluctuations in power we want to see.”
Since power output is an often misunderstood metric, Bryan says he usually focuses on an athlete’s ability to improve miles per hour over a longer period at a lower heart rate. It’s about managing your energy reserves and doling out effort appropriately to finish strong.
“The more times a triathlete has to ramp up power in a race, the greater level of stress placed upon the body,” he says. Of course, you’ll likely need to increase your power output on hills, passing in a non-draft-legal race, or finishing the bike leg, but the point is to minimize the fluctuations.
What the variability index indicates is an athlete’s fastest speed for the lowest effort before reaching a point of diminishing returns. A power meter is the best tool to monitor your output on the roads as it helps you hold back from putting in too many anaerobic surges that will require subsequent slow-downs to re-oxygenate your muscles. By taking your normalized power divided by your average power, you’ll have your VI. Over the long haul, a lower VI is optimal because it means you maintained a steady power output.
“Ideally I want my clients to race at full power with as few fluctuations as possible,” Bryan says.
Ultimately the course and race itself will help determine your pacing strategy, particularly if it offers a lot of hilly terrain or requires tactical racing. While some surging may be necessary, over the long haul it’s all about harnessing a smooth and consistent ride.
Keep your Variability Index Low
– Monitor how hard you put pressure on the pedals at your goal power output. If the pressure changes, you need to shift or modify cadence.
– Instead of blasting up hills, apply a bit of extra effort without going overboard.
– Cut down on the amount of coasting you do to keep a relatively steady effort (a good rule is to coast once you’re naturally going over 30 mph).
– Train on terrain and in conditions similar to your race. This will help you learn to regulate your effort, whether it’s over hills, around corners or on straightaways.