3 Great Aerobic threshold workouts

http://www.active.com/mountainbiking/Articles/Three_great_aerobic_threshold_workouts_for_mountain_bikers.htm
sourced from Active.com on 4/3/2011

Edmund R. Burke, Ph.D.


Active.com



While endurance training is the backbone of a mountain biking fitness program, in order to compete in racing one needs to compete at a heart rate that can be maintained for 15 to 45 minutes of decidedly hard effort, most commonly on climbs.

At this point you are riding at the threshold between where the energy for muscular contraction is coming primarily from aerobic metabolism and where anaerobic metabolism begins to kick in at a high rate.



Once you pass the threshold, the muscles produce excessive amounts of lactic acid which begins to accumulate in the body. The process of lactic acid production begins to shut down the metabolic mechanisms within your muscle cells, and because it is an acid, you experience that familiar burning sensation in your muscles.



For most fit athletes this will be between 80% and 85% of their max heart rate. When training in this zone, the primary benefit to you is an increase of the speed or effort that you can work at before you cross over into the pain of lactic acid accumulation. Provided you have the proper aerobic base built from primarily endurance work, this training could well provide the level of training your cycling is missing.



When you are riding at this intensity you will experience heavy breathing, tired muscles and fatigue. And when you train at this effort, you will experience a training effect that will allow you to sustain more work at higher intensities at a lower heart rate.



The importance of training at lactate threshold is significant for several reasons. If everything else were equal, the higher your lactate threshold, the faster pace or speed that can be held over long distances or steep climbs. While success in off-road events is in part related to high maximal aerobic capacity and the ability to descend quickly on gnarly single tracks, it also requires cyclists to compete at a high percentage of their maximal capacity.



The training programs listed below will help you raise your threshold from 75-80% to the 85% level found in elite cyclists. This means that you will be able to ride at a pace closer to your maximum oxygen consumption without accumulating excessive amounts of lactic acid.



What does this mean? Well, youll be able to raise your speed on a long steep climb lets say from 10 m.p.h. to 12 m.p.h. You will also be able to breakaway with fitter cyclists, climb hills stronger and attack with more speed, but only after you have the proper base of endurance conditioning. If you dont have the proper base of aerobic conditioning, these workouts will tear you down rather than build you up.



If youre not already not using lactate threshold training, try adding a little to your weekly program. Start off with one session per week, and gradually increase the intensity and length of these sessions. Dont increase the frequency once a week is plenty. Your race performances should improve as your lactate threshold goes up.



Long intervals:



These intervals range from 1 to 5 minutes long.



A good plan is to start with shorter intervals. Then as you become more fit, lengthen the intervals. Many cyclists consider 1 to 2 minute intervals short, while 4 to 5 minutes would be long. Gradually raise your heart rate to lactate threshold level and maintain it to the end of the interval.



The rest intervals between the intervals should be in the 2 to 5 minute range or to when you heart rate returns to about 120 beats per minute, although the length of recovery will vary with the length and the intensity of the interval. Ride easily during recovery until you feel you have recovered for the next interval.



Start with 3 or 4 intervals then gradually increase the number of intervals, 5 or 6 is plenty. As you increase the number of intervals you should also increase the length of each interval until, after several months, you can complete two sets of five, five-minute intervals. In the early part of the season use your middle chainring. Once you are into your heavy racing season, use the big chainring.



Timed-hill interval



Mark off a known distance on a hill that will require about 5 to 7 minutes to ride at threshold heart rate. Then ride the distance and record your time and ending heart rate. The goal is to try and lower your time, while not going over your threshold heart rate during the interval.



Lactate crisscross training



You need a heart rate monitor with a high/low "target zone" system. Simply set the lower alarm on your monitor about eight beats below your lactate-threshold heart rate and the upper alarm about five to six beats above your lactate threshold heart rate.



After a good warm-up, increase your speed or intensity steadily until the upper alarm goes off, then gradually slow your pace until the lower alarm sounds. Travel back and forth between the upper and lower alarms, taking about 2 minutes to make each ascent and descent. Again add time to each interval and number of repetitions to your workout as your fitness progresses during the season.