To do a power interval, put your bike in a high gear and pedal at maximum intensity on a flat stretch of road for 20 seconds. Recover at a low to moderate intensity for two to five minutes after each power interval. Start with a total number of power intervals you can comfortably manage and add a couple each week. Warm up for at least 10 minutes before your first power interval and cool down for at least 10 minutes after your last one.
Short hill climbs: Short hill climbs are performed at a very high intensity—about 95 percent of your maximum power output. They boost aerobic capacity and resistance to muscular acidosis and enhance your ability to recover quickly.
Choose a hill with a moderate grade (six to eight percent) and select the most efficient gear for climbing the hill quickly. Each climb should be 30 to 60 seconds in duration. Ride at the highest intensity level you can sustain through the end of the final-scheduled climb without slowing down.
Recover between intervals by coasting back down the hill and pedaling easily for two minutes. Again, start with a manageable number of climbs and add a climb or two each time you repeat the workout. Don't exceed 20 total minutes of climbing. Warm up thoroughly before doing a set of short hill intervals and cool down thoroughly afterward.
Speed intervals: Speed intervals are short (30 to 60 seconds), fast intervals that develop aerobic power, efficiency at high speeds, resistance to muscular acidosis and the ability to recovery quickly between largely-anaerobic efforts. Do them at the fastest pace you can sustain through the end of the last prescribed interval without slowing down.
Spin for two to three minutes after each speed interval. Always perform speed intervals on flat terrain or on an indoor trainer. Warm up and cool down thoroughly. Start with a manageable number of speed intervals and build gradually.
A sensible schedule for speed intervals in a half-Ironman program is one set every other week between weeks five and 11 of a 20-week training program. Do a set of short hill climbs in the alternate weeks (weeks six to 12).
In the final weeks of your half-Ironman training program, your anaerobic training can be limited to a few scattered jumps (short sprints) and hill attacks in your base rides and longer rides and perhaps a few speed intervals in a mixed-intervals workout emphasizing longer efforts. That's all you'll need to give you that last five percent of muscle energy for your best half-Ironman bike performance.
A regular contributor to Runner's World and Triathlete, Matt Fitzgerald is also the author of several books for triathletes and runners, including Triathlete Magazine's Essential Week-by-Week Training Guide, and Triathlete Magazine's Complete Triathlon Book.
Reprinted courtesy of Triathlete magazine. For more articles and information from Triathlete, please visit www.triathletemag.com.