Athlete's Weight Loss

Implementing VO2 Max Test Results

Training Intensity Zones

Seven zones for training intensity are described below.  Each intensity zone stimulates a specific desired adaptation that will enable you to race more effectively.  Make sure that every workout has a specific purpose and maintain the appropriate intensity to achieve that end.

Zone 1

Zone 1: Active Recovery: Active recovery is not a workout that will make you stronger and fitter, but simply help you recover from yesterday's hard workout so that you can have an effective workout tomorrow. The goal is to maintain an intensity that is high enough to stimulate increased circulation to deliver nutrients to the muscles and to remove toxins, and hard enough to stimulate a growth hormone release (which speeds recovery), but not high enough to demand more recovery. This is an extremely low intensity level that doesn't even seem like training.

Zone 2

Zone 2: Basic Endurance Training. Aerobic threshold is the intensity at which almost all of the slow twitch (endurance) fibers are being used, but none of the fast twitch (speed-endurance or sprint) fibers are. Basic endurance training is best accomplished at or slightly below aerobic threshold intensity. Basic endurance training forms the backbone of any good aerobic training program. This training should comprise a higher percentage of most training programs. Most athletes spend too much time running medium-hard and would do better to slow down for most of their training. Almost everyone will benefit from slowing down for most of their training and speeding up for a small part, staying out of the medium-hard intensity range.

Zone 3

Zone 3: No Man's Land. In Zone 3, the body is recruiting all of the endurance fibers and some if the speed-endurance fibers. At this intensity fuel use has shifted significantly away from fat and the muscle burns mostly sugar. At this intensity you aren't going hard enough to stimulate the changes we get from hard training, but you are going fast enough to deplete yourself for tomorrow's workout that is designed to make you faster. Mostly, zone 3 training should be avoided

Zone 4

Zone 4: Lactate Threshold Training. Lactate threshold is the highest intensity at which the muscle can recycle lactic acid as quickly as it is produced. This is a fairly hard intensity and the acid level in the muscle will be moderately high, but not increasing over time. Speed up just a little bit, and acid starts to accumulate. At lactate threshold intensity, you are going hard enough that all the slow twitch (endurance) muscle fibers are being used, and all of the fast twitch type A (speed-endurance) fibers, but none of the fast twitch type B (sprint) fibers. This is a very efficient training intensity, providing an excellent cost-benefit ratio.

Zone 5A

Zone 5a Super-Threshold Training. Zone 5a is often referred to as super-threshold pace. Intensity is slightly above lactate threshold, so lactic acid is accumulating in the muscles and in the blood. At this intensity, lactic acid accumulates gradually so that this intensity can be sustained for a relatively long period of time. This is a very inefficient training intensity. If you exercise at 101% of lactate threshold intensity, the acid level doesn't increase top 101% of LT level and plateau. As long as you are over LT, acid accumulates. This is fine for a couple of minutes but, if sustained the acid level may rise to twenty percent higher than at LT. This does a lot more damage to the muscles and makes the workout much harder both physically and psychologically – all for a 1% better workout.

Zone 5B

Zone 5b Aerobic Capacity Training: Maxing the VO2. Maximal aerobic capacity or VO2 Max, the amount of oxygen consumed in one minute of maximal aerobic exercise, is widely considered the standard test for aerobic conditioning. Improving VO2 Max is a crucial step in maximizing endurance performance in any event lasting four minutes or longer. The higher an athlete's VO2 Max, the greater the contribution of the aerobic system to energy production. This translates into greater endurance at any intensity. Most people perform aerobic capacity (interval) training too hard, exercising at a level that increases anaerobic metabolism dramatically for no benefit. Learning to perform interval training at the lowest intensity that maximizes aerobic metabolism is critical.

Zone 5c

Zone 5c Economy Training: Maxing The Gas Mileage. Economy or efficiency plays a major role in endurance performance. In addition to optimizing technique, regularly performing short, very fast repeats with full recovery between efforts is a key way to maximize efficiency at any speed.

Perceived Exertion

Perceived Exertion is the most basic method of measuring intensity.  How hard does it feel?  For an experienced athlete, even when using more technology to monitor intensity, staying in touch with perceived exertion is critical.  Perceived exertion is an excellent means of monitoring intensity because it is always available and convenient, because it takes into account an array of different variables that might affect fatigue, and because this is the key factor when racing.

The potential pitfall of training by perceived exertion is its subjectivity.  Athletes who train only by perceived exertion tend to train faster on days when they feel good, which is not efficient.  Optimal training intensity is the same on a day when you feel strong and controlling intensity is a key to having better days for all your workouts. 

Experienced athletes have learned precisely how each intensity level should feel and perceived exertion can be very effective.  Until the athlete has learned specifically how aerobic threshold, lactate threshold, aerobic capacity pace, economy pace, etc. feel, using perceived exertion is simply training by intuition.  Training by perceived exertion is a completely different thing from "training by feel".  Training by perceived exertion involves a knowledgeable and experienced athlete who knows what the most efficient training intensities are and uses how the body feels to monitor intensity.  Many athletes train by feel, using intuition instead of running at the optimal intensities.  Stay away from training by intuition. 

Whenever you train, tune in to how your body feels.  How hard am I breathing?  How much force am I using to push off the ground?  What is my turnover?  What, if any, is the level of burning in my legs?  How heavy do I feel?  When I ask my legs to accelerate, how do they respond?  Which muscles in my legs feel fatigue?  Learn to associate these different feelings.  For instance, if your legs begin to show signs of fatigue at a lower respiration than normal, that is important.  Stay tuned into how these factors interrelate.


Running speed is another important measure of training intensity. One of the major benefits of training by speed is its objectivity. Seven minute miles are seven minute miles. Also, speed is ultimately what wins races. The purpose of training is to make us faster, not to enable us to hold a higher heart rate, greater blood lactate levels, or higher perceived exertion.

The potential detriment of training by speed is that intensity at a given running speed may be quite different in different environmental conditions. Seven minute miles uphill, into a headwind, on soft ground, on a 100 degree, 100% humidity day is quite different from the same pace under different conditions. The same pace, under ideal conditions, may be a quite different intensity for the same athlete on different days. On a day when you didn't sleep well the night before, the day after a hard track workout or long run, or the first day back from an extended rest period, seven minute miles will be different effort levels. When training by speed, always tune into other methods of monitoring intensity. Several companies have developed GPS systems that essentially function as a speedometer for runners. These can be a very effective tools if used properly. Just as with all the technology, don't rely too heavily on this feedback. Use this technology, and all the other tools for objectifying intensity to train and continually recalibrate your sense of perceived exertion.

Heart Rate

Heart rate has become the most widely accepted technology for monitoring intensity, and with good reason.  Heart rate is a relatively inexpensive, convenient, and effective method of monitoring intensity.  The athlete wears a strap around his chest which tracks the electrical activity of the heart and transmits a signal to a wrist unit (or a handlebar mounted unit for cycling) which tells how many times per minute the heart is beating.  Heart rate will generally follow a consistent pattern, increasing as intensity rises and decreasing as intensity falls.  The athlete then trains by heart rate zones, with each zone keeping him near the optimal intensity for each specific type of training.

As with any technology, one pitfall is over reliance on the heart rate monitor.  Many athletes think that heart rate is the end-all and the be-all of training and racing.  It is not.  I knew one man who had a terrible race after the battery in his heart rate monitor died.  Had he tuned into perceived exertion while he trained with his heart rate monitor, he would have been able to race effectively with a dead battery.  Another athlete I coached set a 40K PR by over a minute, but was furious that he hadn't averaged the heart rate he had hoped to.

Smart athletes use a heart rate monitor in conjunction with other measures, especially perceived exertion and pace, to learn how their body functions.  The heart rate monitor can become an incredible teacher for you if you stay tuned to other factors while watching heart rate and don't approach its use legalistically.  Pay attention to heart rate and how it reacts in different situations, but don't become a slave to your heart rate monitor.

Speed and Wattage

Heart rate monitors are the single most effective way to monitor exercise intensity for basic endurance and lactate threshold workouts, but for aerobic capacity (interval) workouts, using speed or power is a more effective way to monitor intensity. Since the efforts are so short in duration, heart rate is a less effective method for these workouts. Power meters provide cyclists with instant feedback of how much power they are producing. For aerobic capacity workouts, this is the ideal method for monitoring intensity because it gives immediate feedback. With GPS technology, runners now can get instantaneous feedback about speed, which is equivalent to the data provided to cyclists by power meters (as long as the runner is on flat ground). Even without GPS, runners get frequent feedback on speed when performing interval workouts on a track or treadmill. Conducting a six minute time trial to measure cycling wattage or running speed is the most effective way to precisely manage intensity for aerobic capacity (zone 5b) workouts.

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