Aerobic Threshold (Page 2)

The zone breakdown above is not the most commonly accepted pethod for us triathletes to use.

Most people agree that the best method is using Lactate Treshold. For that purpose read this thread "HR Zones: 220-Age - the TRUTH!".

I also would like to add that z3 is a zone an athlete SHOULD try and stay out of since it does not exercize conveniently any of the two main energy systems, and therefore does not contribute enough to proper endurance development. It is generally preferable that an athlete stays in z1 and z2 (80% of training time) or above such as z4 (tempo runs) or z5a (intervals) etc. z3 may be convenient only for trained athletes for specific types of competition such as long and ultra long distances.

Below is a thorough review of each of the training zones, according to Joe Friel's Training Bible zones.

Ken


Training Intensity
The single most critical factor in endurance training is intensity. In any structured training program, each workout should have a specific purpose. To achieve the ideal response from the body, the stimulation must be specific to the desired adaptation and must allow quick recovery for the next key workout. Intensity, more than any other variable, determines the body’s response to the training stimulus.
This absolutely does not mean that harder is better. The optimal training schedule for any athlete provides the lowest volume and intensity that will stimulate the desired adaptation, not the highest the athlete can sustain. This is a major paradigm shift for many endurance athletes who grew up hearing, “No pain, No gain.” If mile repeats at 5:08 stimulate increased aerobic capacity, then that is how fast those workouts should be performed even if he can run repeats at 4:55. Being a “tough guy” and always going harder and harder will not yield ideal results.
Tough guys never seem to get any faster, they just get tougher … and it seems like fast guys are always winning the races.
Training efficiently means balancing the cost and benefit of each workout. Every workout has a cost, in terms of recovery. Every workout also increases fitness. Efficient workouts provide training benefits that are worth the recovery cost. Every athlete at any point in time has certain recovery resources. While smart athletes develop habits to maximize these resources, they will always be finite, and need to be budgeted. Anything that is going to expend these resources needs to provide a proportionate benefit.
Recovery resources include, among other things:
• Glycogen Storage: Glycogen is the form of carbohydrate, stored in our muscles and in our liver that serves as the primary fuel for endurance exercise. Hard or long workouts expend tremendous amounts of glycogen and demand full fuel tanks at the beginning of the workout. Maintaining optimal intensity makes best use of this limited resource.
• Muscular Recovery: Muscles sustain damage during running workouts. Lactic acid accumulation damages the muscles chemically and impact stress damages the muscles mechanically, producing tiny tears called micro-trauma.
• Connective Tissue Damage: Every workout, but especially a run workout, stresses and damages connective tissues. These tissues need to heal and rebuild adequately between workouts.
• Injury Risk: Injuries are an ever-present risk in any workout, especially run workouts. During high-volume or high-intensity workouts, risk for injuries increases.
Maintaining optimal intensity during every workout is a key aspect of managing these risks. These are all limited resources, and running at the right pace during each workout makes the best use of them. This allows you to benefit maximally from each workout and gets you ready sooner for the next key workout.
Remember that it is the quality of the individual workout that makes an athlete stronger and faster, not just an accumulation of stresses. Many athletes train medium hard all the time. On their hard days, even if they put in 100% effort, they don’t get 100% speed because they are a little tired from yesterday’s workout or from an accumulation of weeks of training without quite enough recovery.
If you should be running 800s at 2:42, but you keep hitting 2:46 because you are fatigued from yesterday, that is bad training. Your legs don’t respond or improve from your 100% effort, they just respond to 2:46es. That is training yourself to run slow even though you’re working hard and it is bad training.
Muscle Fiber Recruitment
Each muscle in our bodies is composed of thousands of muscle fibers. These muscle fibers come in three basic types. Each of our muscles is composed of some combination of these three types, the percentage of each type depending on individual genetics.
Slow twitch muscle fibers are our endurance fiber. They can keep going all day long, but they are not big, fast, strong, or powerful. Slow twitch muscle fibers are able to burn either fat or carbohydrate for fuel, depending on the intensity.
Fast twitch muscle fibers are our sprint fibers. They are big, fast, strong, and powerful, but they fatigue very quickly. Fast twitch muscle fibers cannot burn fat for fuel.
Our muscles also have an intermediate fiber which produces more power than slow twitch fibers and has greater endurance than fast twitch fibers. These fibers are called F.O.G. fibers (fast oxidative glycolytic) and I refer to them as your speed-endurance fibers.
Every muscle in an athlete’s body is composed of many thousands of muscle fibers. When the muscle contracts, each fiber either contracts with its full force capability, or remains relaxed. When an athlete picks up a one pound dumbbell, very few fibers are required to contract, but those that do contract just as powerfully as when they pick up a seventy pound dumbbell.
After aerobic plateau, which requires several minutes at the beginning of each workout (and each shift in intensity during a workout), the athlete’s body will recruit muscle fibers according to the power or speed requirement of the activity. The endurance fibers will be recruited first. At low intensity only a few endurance fibers will be recruited. As intensity increases, the speed endurance fibers will be recruited next, and finally the sprint fibers.
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: Active Recovery
Sometimes an easy workout promotes recovery better than a day of complete rest. The key is maintaining a VERY low intensity. 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.

Many athletes and coaches will tell you that “recovery run” is an oxymoron. While I agree with this in general, the effectiveness of using running for active recovery is very much an individual thing. Some athletes can go for a short, easy run and recover very quickly for the next workout. Many find that easy runs, over time, run them into the ground and/or increase overuse injuries. How much this has to do with physiological individual differences vs. differences in the discipline to maintain correct active recovery intensity is unclear. Certainly both are factors. When in doubt, use swimming or cycling as active recovery workouts.
Zone 2: Basic Endurance Training
Aerobic threshold is the intensity at which almost all of the endurance fibers are being used, but none of the speed-endurance or sprint fibers. Basic endurance training is best accomplished at or slightly below aerobic threshold intensity. Basic endurance training forms the backbone of any good triathlon run training program. This training should comprise a higher percentage of most triathletes’ training programs. Most triathletes spend too much time running medium-hard and would do better to slow down for most of their training.
Diagram 5-2
Running at a basic endurance pace, in heart rate zone 2, trains the endurance fibers. These fibers have tremendous capacity for endurance, but not much capacity for speed. They do most of the work in any triathlon. Endurance fibers generally produce 65 – 75% of the energy in for an elite athlete in an Olympic-distance race and well over 90% in an ironman distance race. Slower athletes rely even more on the slow twitch muscle fibers.
These muscle fibers can withstand and benefit from enormous training volume if intensity is appropriate. At higher intensities, muscle fibers that lack the endurance capabilities of the slow twitch fibers are recruited. These fibers cannot withstand training volumes appropriate for the slow twitch fibers. Training just a little too fast during basic endurance workouts reduces
At basic endurance intensity, the muscles burn a relatively even mixture of fat and carbohydrate for fuel (individual differences in genetics and training affect this somewhat). Since fat is such a concentrated energy source, containing about 2.25 times as much energy per gram as carbohydrate, even the leanest athlete has enough fat stored to run many, many miles.
When intensity increases above basic endurance pace, the muscle shifts over to burning more carbohydrate and less fat. This happens for two reasons. First, the body must begin recruiting some of the speed-endurance muscle fibers, which do not burn fat effectively. These fibers compete with the endurance fibers for available oxygen, so the endurance fibers lack adequate oxygen to burn fat and begin to burn more carbohydrate. This depletes muscle and liver glycogen storage unnecessarily. Many athletes run their basic endurance workouts just slightly too fast, depleting resources and delaying recovery for tomorrow’s workout. Doing basic endurance workouts too fast won’t make you faster.
Training at this intensity for running will include long runs, long bricks, and moderate duration midweek endurance runs. Warm ups for higher intensity runs also take place at basic endurance intensity.
Zone 3: Tempo Training
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 really going hard enough to make yourself faster, but you are going fast enough to deplete yourself for tomorrow’s workout that is designed to make you faster.
Diagram 5-3
This intensity zone can be effective for maximizing carbohydrate storage in the muscles and for preparing the body for the demands of higher intensity training. Zone 3 training should only be used early in base training, when there are no high-intensity workouts to interfere with, or during the build and peak periods when training for races which will take place at this intensity (race pace training). Zone 3 training has its place, but most athletes spend too much time at this intensity.
Zone 4: Lactate Threshold Training
Whenever an athlete exercises at any intensity, even walking, lactic acid (lactate) is constantly being produced. Fortunately, our bodies also constantly recycle lactate, actually burning it up and using it for fuel. As intensity increases, lactate production also increases. Lactate threshold is the highest intensity at which an athlete recycles lactate as quickly as it is produced, so that lactate does not accumulate. Muscle and blood levels of lactate are moderately high at lactate threshold intensity, but do not increase over time. Increasing pace just slightly will cause lactate to accumulate, increasing discomfort, damaging the muscles, and delaying recovery for tomorrow’s workout.
Diagram 5-4
You may have heard the terms lactate threshold, anaerobic threshold, and ventilatory threshold. These terms refer to three different ways of measuring the same intensity and may be used interchangeably.
Lactate threshold training, in the right doses at the right time of season, is important for almost every triathlete. For most athletes lactate threshold training has the best cost to benefit ratio of any type of training. This intensity is high enough to stimulate adaptations which dramatically increase speed-endurance, but because lactate is not accumulating, damage to the muscles and blood vessels is minimal and the recovery cost of the workout, if conducted properly, is modest.
At lactate threshold intensity, the body recruits all of the endurance muscle fibers and all of the speed-endurance fibers, but does not recruit the sprint fibers. Just as the endurance fibers can sustain much higher training volumes than the speed-endurance fibers, the speed-endurance fibers can withstand much, much greater training volume than the sprint fibers.
At lactate threshold (LT) intensity, the speed-endurance fibers create a lot of lactic acid, but only at a rate at which the endurance fibers can burn it up and use it for fuel. Sustaining this intensity trains the speed-endurance fibers to work more aerobically so that they produce less acid and trains the endurance fibers to burn more acid, both of which push the threshold to a higher speed.
LT training is the only effective endurance training for the speed-endurance fibers. At lower intensities they are not recruited. At higher intensities, sprint fibers are recruited causing lactate to accumulate. This reduces the duration that the athlete can sustain the intensity and dramatically delays recovery.
Most athletes and coaches overestimate lactate threshold intensity and, when running at the correct pace, feel like they are not going hard enough. This creates a major problem, either limiting potential training volume or inducing overtraining. Training one percent over lactate threshold, at an intensity at which lactate accumulates slowly, causes much greater damage and requires much greater recovery time than the same duration at lactate threshold. Reducing training volume or suffering overtraining are poor tradeoffs for the slight benefits from the 1% increase in intensity. For a twenty to thirty minute segment, it does not feel that much harder. Lactate accumulates slowly, but continually, and does damage in the muscles that the athlete cannot necessarily feel. Five minutes into a segment at 101% of lactate threshold, lactate levels in the muscles and in the blood will be only slightly higher, but later in a long set they may be dramatically higher. Muscle damage and recovery time may increase enormously. A well trained athlete can sustain lactate threshold intensity for seventy five minutes or more with 100% effort, such as in a race.
There are two basic formats for LT training, cruise intervals and tempo segments. Cruise intervals alternate four to six minute segments at lactate threshold with one to two minute recoveries. Tempo segments are hard and steady segments of twelve to sixty minutes at or slightly below LT pace. Each has specific uses and benefits.
Cruise intervals are four to six minute segments at lactate threshold with one to two minute recoveries. These are very effective for introducing higher intensity training during late base periods. The recovery cost of cruise intervals is relatively light and the damage from accidentally running slightly above LT intensity not as great.
Relatively long tempo segments are the core of LT training. These efforts are hard and steady. The legs will feel a mild to moderate burn and breathing will be hard, but controlled. Athletes who time their breathing to their steps probably inhale for two steps and exhale for two steps. It is important to maintain a steady effort for LT tempo segments. Most athletes tend to run up hills above LT intensity and relax on the down-hills, allowing effort to fall below desired intensity.
Training slightly below LT and training right at LT have different benefits and detriments. Both are important to efficient training. Steady efforts right at LT are effective for increasing speed at LT, while longer efforts slightly below LT increase endurance at LT. An athlete may have an LT of 6:00 per mile and be able to sustain that intensity for seventy-five minutes. Training right at six minute pace (high zone 4) will increase his LT speed to 5:50. Longer segments at 6:20 pace (low zone 4) will enable him to sustain 6:00 pace for longer than seventy-five minutes.
High zone 4 is right at to slightly below LT. Heart rate is sustained approximately 0-4 beats below LT and speed stays within three to five percent of LT. I generally use twelve to twenty minute segments at this intensity will increase speed at LT.
Low zone 4 is somewhat below LT, with heart rate is sustained approximately 5-8 beats below LT and with speed about four to six percent below LT. At this intensity, most of the F.O.G. fibers are still recruited, but there is a safety zone against lactate accumulation. During the build periods, I have athletes perform tempo segments of twenty minutes all the way up to an hour at this intensity.
Training in the lower end of zone 4 increases the endurance of the FOG fibers, enabling the athlete to sustain LT wattage or speed longer. I believe that this is an incredibly efficient training intensity. The cost, in terms of recovery for tomorrow’s workout as well as the psychological cost, is relatively low. Most athletes enjoy this training and, prescribing very long sets may increase compliance with intensity. If I’m doing a forty minute segment, it is not so tempting to want to run too fast.
Every athlete likes to think that they are more motivated than the rest. They will train harder, be more consistent and more disciplined. Coaches like to think the same about their clients. Remember though, no matter how passionate and motivated the client is, this is a finite resource. Budget it wisely. Correct use of LT training, generally a little on the conservative side, plays a big role in sustaining motivation.
Maintaining appropriate intensity for these workouts is critical. Zone 4 is very efficient training. Understand that, if the optimal intensity is 171 to 177 beats per minute, it is recommended because that intensity produces the best results, not so that you can finish the forty minute segment. Joe Friel frequently recommends, “The least amount of work which will produce the desired results.” Remember the tendency of every athlete to want to go as hard as possible for whatever the duration. That does not produce the best results.
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 long period of time.
Diagram 5-5
Many athletes mistakenly train in zone 5a when they intend to be in zone 4 doing lactate threshold training. This is a costly mistake because the recovery time from zone 5a training much greater than from zone 4 training. Since lactic acid accumulated very slowly in zone 5a, the difference between 4 and 5a is negligible when sustained for short periods of time. However, when sustained for moderate to long durations, the acid accumulation does significant damage to the muscle cells and requires significantly more recovery time.
Zone 5a training is excellent for improving lactate tolerance. The muscles are trained to continue to produce speed efficiently despite the buildup of acid. This is a benefit, but it comes at a great cost in terms of the volume and intensity of other workouts.
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.
Each muscle fiber type has both aerobic and anaerobic capabilities. Endurance fibers are mostly aerobic but do have some anaerobic metabolism. Speed-endurance fibers are more balanced. Sprint fibers are mostly anaerobic, but their aerobic abilities can still be important in racing. Aerobic capacity workouts improve the aerobic capabilities of the sprint muscle fibers.
Stimulating these adaptations requires maintaining an intensity that is high enough to demand recruitment of the sprint fibers, but low enough to enable the athlete to sustain the intensity for a duration that will stimulate aerobic adaptations in those fibers, instead of only anaerobic adaptations.
Aerobic Capacity Pace
To improve aerobic capacity in a well-trained athlete, training should take place at about 95% of VO2 Max. While the results of a VO2 Max test can be useful in pinpointing optimal training pace for aerobic capacity training, research shows that field testing determines optimal intensity very effectively.
Since field testing incorporates psychological as well as physiological variables, and since it is more practical, that method is used most frequently. Perform a time trial on a track of six to eight minutes. Make sure to be well rested before the time trial. Monitor speed and heart rate during the test, checking splits every quarter mile. The highest intensity that can be sustained for six minutes produces optimal results. We refer to this as six minute tome trial pace (TT6).
The intensity (heart-rate and/or speed) determined by the field test is how fast all aerobic capacity workouts should be conducted. It is not correct to go faster when performing shorter intervals or repetitions and it is not correct that intervals should be performed as fast as possible. Training beyond the optimal intensity has no additional benefit to the aerobic system, yet comes at a great cost in terms of the body’s recovery resources. Energy to increase output above 6-minte race pace is derived almost 100% from anaerobic sources and therefore will not increase aerobic capacity. When in doubt, err on the conservative side with aerobic capacity training. It can be a powerful tool, but a little bit goes a long way.
The pace determined by your field test could feel too easy for several reasons. You could have improved conditioning or economy since your last test. You could have used less than full effort in the test. Or you could be accustomed to performing track workouts too fast for an endurance athlete. Before you increase your interval pace, prove that you need it with a faster field test.
Duration and Work/Rest
To increase aerobic capacity, an athlete needs to spend considerable time performing near maximal oxygen consumption. Raising exercising VO2 involves both an intensity component and a duration component. Even when performing at a very high intensity, it takes one minute and forty seconds to two minutes to elevate oxygen consumption to the levels necessary to optimally increase aerobic capacity. So, running six sets of two minutes at aerobic capacity pace and running for twelve minutes near max VO2 are quite different. There are two ways to maintain oxygen consumption near VO2 Max for extended durations in a workout: repeat training and interval training.
Repeat training involves relatively long repetitions with basically full recovery between sets. Since approximately two minutes are required to optimally elevate VO2, repeats need to be considerably longer than two minutes. In a sense, the benefits are only starting at the two minute point, when oxygen consumption has climbed to near maximal levels.
One workout using repetition training would be four repetitions of four minutes each at six minute time trial pace. Obviously this is an extremely taxing workout. Since each repetition yields about two minutes performing near maximal aerobic capacity, this workout will provide about ten minutes near max VO2. This type of workout should be used primarily during late Build and Peak periods. It is also effective in developing lactate tolerance and in preparing an athlete psychologically for the demands of racing. Be conservative with this training because it is extremely costly to the athlete both physically and psychologically.
A second way of maintaining elevated VO2 for extended periods is interval training. Performing shorter repetitions at the same intensity (six minute time trial pace), but minimizing recovery between repetitions leads to increasing VO2 throughout the set. Reducing the recovery causes the athlete to begin each repetition at a higher VO2 than the previous rep, so that through most of the set the desired near-maximal oxygen consumption is attained much earlier in each repetition. In the example in the previous paragraph, the athlete performed at TT6 for twenty minutes but only about half of that time was spent near max VO2. An athlete performing a set of short-rest intervals may keep VO2 elevated for a much greater percentage of the set duration.
Be careful not to perform at a higher intensity during shorter intervals. Going above TT6 will not increase aerobic gains, but will increase the recovery cost dramatically.
The classic aerobic capacity set is five sets of three minutes at TT6 pace with a three minute recovery jog. This is a hard workout that needs to be built up to.
Another very effective aerobic capacity workout is called 30/30s. This workout involves 30 second repetitions at TT6 pace with 30 second recovery jogs between each repetition. This is an extremely efficient workout. The benefits are extremely high and aerobic capacity and high-speed endurance may be increased dramatically, but the cost of the workout (recovery cost and psychological cost) is relatively low since lactic acid doesn’t accumulate to a great degree because of the short repetition duration and the acid can be recycled during the recovery periods.
As repetitions get longer, work-to-rest ratio must increase. Even with a short work repetition, such as 30 seconds, 30 seconds is not enough time for a huge drop-off in VO2. With a longer, say two minute, repetition duration, a 1:1 work-to-rest is not great enough. I generally limit interval recovery to about a minute between repetitions and consider anything over a minute to be almost full recovery. Even after a hard repetition, oxygen consumption decreases dramatically with significantly more than a minute recovery and the next repetition will require the full two minutes to elevate to near max.
Another effective workout that combines lactate threshold training and aerobic capacity training involves running a segment at LT followed immediately by a segment at TT6 pace. This type of workout is effective because oxygen consumption is already considerably elevated at the beginning of the TT6 repetition, so the athlete reaches the near-max oxygen consumption much more quickly than when starting from rest or from basic endurance pace. For more details about these workouts, see appendix A.
Begin aerobic capacity training conservatively. It will probably be a significant increase in intensity for most athletes. I recommend starting with short-rest intervals, like 30/30s, for about 8-12 minutes of “on” time and building volume slowly, but consistently. Gradually shift to sets with longer repetitions. Monitor your recovery response carefully because it varies considerably between individuals. Many athletes, even those who tolerate high training volume very well, break down easily with aerobic capacity training.
Economy Training: Maxing The Gas Mileage
As discussed in great detail previously, economy or efficiency plays a major role in fast distance running, especially after hard cycling. Technique plays an important role in improving economy, but training does as well. Increasing the strength, endurance, and elasticity of your tissues properly and training the muscles to contract and relax at exactly the right moments during high running speed. Remember that one percent of an hour is thirty-six seconds. A one-percent improvement in economy goes a long way toward a triathlon run split personal record.
Developing optimal strength is critical to efficient running. Strength training in the weight room will be covered in Chapter 12. Reaching ideal race weight also affects running economy. Details on that will be covered in Chapter 8.
Economy training involves very fast runs over a short distance interspersed with relatively long periods of slow running to allow nearly complete recovery between repetitions. Economy workouts should not be fatiguing at all. The major variables in a repetition workout are pace, duration of repetitions, duration of recovery period,
Major benefits of economy training include:
• Increasing the elasticity, strength, and quickness of muscles and connective tissues.
• Improving the ability to relax each muscle group at the appropriate time during the running stride.
• Helping to groove correct mechanics, especially the all-important relationship between stride-length and turnover.
Determining Economy Pace
Economy pace is the highest speed at which you can run with good efficiency. As you speed up from easy running paces, you actually become more economical. A runner might increase speed by four percent and use only three percent more oxygen. This trend will continue to very fast running speeds. As you go faster, you gradually become slightly more efficient. At economy pace, this trend reverses. Running one percent faster than economy pace increases energy expenditure by much more than one percent.
Pace is critical because it must be fast enough to force proper mechanics and to powerfully pre-stretch the tissues. Running faster than the correct economy pace changes running technique from a fast but efficient style, to a sprinter’s style, trading efficiency for maximal speed. Running repetition workouts too fast increases the likelihood of over-training and overuse injuries and actually trains the body to run inefficiently. That is the opposite of what is intended.
Economy pace is 5 – 8% faster than TT6 pace. A triathlete who runs a mile all out in 6 minutes should run economy reps between 5:33 and 5:43 (6 / 1.08 and 6 / 1.05). More experienced and more fit runners should stay on the slower side of this scale. Beginner and intermediates will be able to run at the faster end.
Be disciplined with economy pace sessions. Experienced runners can perform these workouts anywhere, but until you have the pace and can reproduce it consistently and accurately by feel, use a track or marked section of road and check your watch. Running too fast may actually reduce your economy. Even though these are very fast sessions, running faster than economy pace is not better. These sessions are not designed to develop you into a sprinter, but to make you more efficient at triathlon race pace.
An economy workout should generally have you running between two and six minutes at economy pace. Ideal duration of repetition is 20 to 45 seconds with a work to rest ratio of at most 1:4. Do not cut recoveries short. These workouts are designed to increase economy and should not become interval workouts. There is no benefit to reducing recovery, but there are detriments.
Economy workouts should be very easy. If they are not, you are running too fast, doing too many repetitions, or allowing inadequate recovery between repetitions. Include economy workouts in your training relatively frequently, but when in doubt, do less.
Economy workouts are ideal during a pre-race taper because they provide enough intensity to maintain red blood cell count and keep your stride sharp and efficient yet the recovery demands are minimal.
Economy training is important for athletes competing at any distance. Many long-distance athletes argue that they don’t need the speed developed by these workouts. Economy workouts should not be performed with the intent of increasing speed. Athletes competing in aerobic events of any duration will benefit from increasing economy. At which distances is an athlete interested in wasting energy?
Hill repetitions may be used as economy workouts when training for hilly events. Be extremely careful to keep turnover extremely high when doing economy work on hills. Start conservatively with relatively few and short repetitions. Remember that different muscles are used in different ways running on hills versus flats. Make sure that all of your training includes a variety of terrains, while emphasizing terrain similar to that of your most important races.
Lactate Tolerance Training: Delaying the Inevitable
At any intensity an athlete’s body produces lactate (lactic acid). At speeds faster than lactate threshold, it accumulates as long as pace is maintained. Some triathletes must slow down as soon as the feel that familiar burn in their legs. Others can continue to run hard, pushing through the pain and effort. The goal on race day is for lactate to accumulate slowly, causing complete fatigue at the finish line, but not before. While lactate accumulation always slows an athlete, the muscles can be trained to perform better under these conditions. Lactate tolerance training increases the body’s ability to buffer lactate in the muscles and blood, keeping pH moderate even at high lactate levels. These workouts also enable the muscles to work more effectively in an acidic environment. These changes enable an athlete to sustain paces well beyond lactate threshold until the race finish.
There is no magic formula for lactate tolerance workouts. At intensities of zone 5a or higher lactate is accumulating. In fact most organized track workouts meet the goals even if their intent was to increase aerobic capacity. To increase lactate tolerance, an athlete must subject the muscles to increasing levels of lactate with recovery periods that are inadequate to return lactate level to normal. There are a number of ways of doing this.
Be extremely careful with lactate tolerance workouts. They can sharpen the edge of an athlete just coming in to peak form, or they can drive the athlete into overtraining. When in doubt, do less lactate tolerance training. A little bit goes a long way.
Monitoring Intensity
Ensuring that you train at optimal intensity for each workout is probably the most important factor in maximizing the benefits of your workouts. There are a number of different ways to monitor your training intensity, each with its own unique benefits and potential pitfalls.
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 knowledgable 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.
Speed
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.
Physiological Testing
Physiological testing by a qualified technician provides the best means of developing specific, individualized training intensities. A properly conducted test using a metabolic analyzer provides data that can be used to produce heart rate zones that are specific to your unique physiology. Unfortunately, the equipment to perform this testing is quite expensive and often technicians have the expertise to perform the test properly, but not to analyze the results to their full benefit.
Testing may be inconvenient and moderately expensive, but it does provide a greater degree of precision to training intensity. If you do have access to a lab facility, I recommend testing. Have tests performed on the bike and the run separately, because the zones may be very different. Make sure that you are fully recovered from training for the test. Any workouts the day before the test should be very light. Don’t eat or consume caffeine for three hours before the test, but be well hydrated. More information about physiological testing is available at www.Fitness-Concepts.com
Determining Training Intensities
To develop heart rate zones, you need to know your lactate threshold heart rate. If you have access to a good lab, this is ideal, but if you don’t you can approximate it using a time trial.
Make sure that you are well rested and find a course that you can run uninterrupted for an hour. Flat to gently rolling terrain works well. A track is ideal. Warm up for at least twenty minutes with several surges of about one minute to approximate one-hour race pace. Run as hard as you can for one hour, averaging your heart rate for the last thirty minutes. The heart rate you could sustain in a workout for the last thirty minutes is approximately lactate threshold heart rate. Do not use a race for this test. Athletes run harder in a race and using an LT that is too high is a prescription for overtraining, not improving. Check your results against the chart below to find your heart rate zones. Lactate threshold heart rate is the number in bold and the zones listed in that row represent your heart rate zones.
Diagram 5-6
Causes of Fatigue
No discussion of training intensity would be complete without touching on the causes of fatigue. The ultimate purpose of all training is to push back the thresholds of fatigue with regards to duration and/or speed. The roots of fatigue will be different for races of different durations, on different terrain, in different environmental conditions, and for different athletes. Determining the most likely causes of fatigue for you in your priority
Ventilatory Distress
In very short efforts, the lungs ability to move enough air to oxygenate the blood may be a performance limiter. The duration of the shortest triathlons is long enough that this will never be a factor. While we will breathe very hard at times during races and our lungs may hurt, they are unlikely to be a limiting factor in triathlons.
Lactate Accumulation
Every athlete knows the burn that accompanies lactic acid accumulation in the muscles. At sprint and international distances, this is the most likely cause of fatigue for most athletes and, for well conditioned athletes lactate accumulation can contribute significantly to fatigue at the half ironman distance.
Fuel Depletion
Almost every triathlete knows what running out of fuel is like. The dreaded “bonk” brings our progress to a halt and causes severe effort and pain even at very slow paces. Certainly triathletes need to avoid bonking. Most triathletes think their engines function like a car’s. When a car has one one-hundredth of a tank of gas left, it still produces full horsepower. The human body doesn’t work that way. Performance declines slightly way before we bonk. Make a greater effort to fuel optimally and you will race faster. See appendixes E and F for more information on fueling.
Dehydration
Water is our body’s most critical nutrient. Just as performance declines with moderate glycogen depletion before we can feel it, we slow down from dehydration long before we feel dehydrated. Most triathletes do a relatively good job of hydrating on the bike during training and races, but do a terrible job on the run. I recommend taking water with you on any run over 40 minutes. Just as you fill a water bottle for a short easy spin, fill a Fuel Belt for most of your run workouts. Consume 20 ounces of water per hour per 150 pounds.
Muscular Fatigue
Lactate accumulation, fuel depletion and dehydration are common causes of fatigue in triathlons, but our muscles can also fatigue for unknown reasons. Even when a well trained athlete stays below lactate threshold and consumed adequate fuel and water, the muscles will eventually fatigue.

Again, training intensity is the single most critical factor in determining your body’s response to training. Training at the appropriate intensity will improve your results more than any other single factor. Make the effort to learn how hard you should be going for each workout and you will race faster this year.

us50090 wrote:

I think until one gets in good enough shape to determine LT, all workouts should be easy. As long as slow, steady running will stimulate improvement, there is no need for anything more intense.

Ken

Holy Cow, Ken, did you get tired of arguing and just decide to post the whole chapter?

Are those your writings or Friels? Curious because I am teaching a fitness class this tuesday to a gropu of mountaineering students and would like to use some of that info in a handout, (sort of like a glossary of terms).

I am trying to udnerstand as much of this myself so that I can simplify things for the students and encourage them to get a good base while the build on the specificity of mountain climbing (e.g. stair workouts with packs & boots)

That is my writing and you're welcome to use it as long as I am credited.

Ken

Absolutely. I see people at the YMCA though that get a HR monitor and think that 155 bpm is good for them because it (hrm) says. IMHO, everyone needs an education on this subject when starting out.

I copied your article into Word and improved formatting for readability. I'm going to give this to my wife to read. She's doing a half-mary in 6 weeks and when I talk to her she's all about "it's too easy" and always wants go go fast. Again, thanks for the info.

Don

Any chance this chart can be described?

Chris,
See one of the posts above with the "HR Zones: 220-Age - the TRUTH!" thread linked. There Mike Ricci has an Excel speadsheet linked in one of the posts that you can download.

Don

... unless I missed something... I don't see the term Aerobic Threshold noted in the long post... but, I know Friel used the term "aerobic threshold".... Looked it up and this is what was wrote...

..............

"Understanding Intensity

.. aroebic threshold... analogous to Lactic Threshold.

Aerobic Threshold - When aerobic metabolism no longer supplies the need for energy. energy is generated aerobically; indicated by an increase in lactic acid. Also know as Lactic Threshold."

.................

And yet, you post this - "Anaerobic or lactate threshold are completely different from aerobic threshold."

Am I missing something? It seems that aerobic threshold is the aerobic side the decriptive term Lactic threshold/anaerobic threshold. Same coin, different side. IMO, it not so much terminolgy as it is application of the terms... which it seems you alluded to frequently in your posts.

I can see why AventureBear would ask the original question. It's confusing when you start looking at the various terms. Friel's definition of Aerobic Threshold is "analogous" to Lactic Threshold... eventhough, the Aerobic threshold is technically anything that is aeroibc (a very broad range - indeed). However, Friel seemed to apply this term in an "analogous" fashion to LT.

BTW, Ken - Good and informative posts.

Joe Moya

Edited by Joe M 2005-10-12 6:51 PM

Joe

Have you read Gordo's Four Pillar's? I think that may be AeT that Ken is referring too...which is more along the lines of top of Zone 1 to Mid Z2. It is confusing when the terminology is changed so often, I agree.

Yes... good reading... and, terms can definately get confusing...

It seems that it's more about application of the terms rather than the definitions...

In the end it doesn't make any difference whether you use near critical power/maximal lactate steady state/"anaerobic" threshold/OBLA or the stranger sounding aeroibic threshold... it's all pretty much about learning that term which applies and use it appropriately.

Joe




Edited by Joe M 2005-10-12 8:10 PM

This is what I take from it, aside from my sherpa analogy which is completely wrong, is this:

Lactate/Anaerobic Threshold defines an LOWER LIMIT of heart rate at which anything above that allows lactic acid to accumulate. TTB zones are defined as %ages of this rate.

Aerobic Threshold is the UPPER LIMIT HR at which everything below is maximal use of slow twitch fibers, with increasing recruitment as the upper limit is approached.

In otherwords, using the term "threshold" to describe both points is misleading because they describe different ends of a spectrum where anaerobic fibers are recruited from the first fiber (aerobic threshold) to the point where lactate accululates fastr than it can be removed (anaerobic threshold).

How's that?

IMHO, that sounds like a reasonable explanation...

But, what makes aerobic threshold difficult to explain or define is because it's not really a truely quantifiable term like the LT/OBLA/Anearobic Threshold/etc.

AT is a term that I see as a Love - Hate sorta' relationship with the more definable LT. It has application value for training purposes, but it also has limited quantifiable value (...unless you consider HR ranges as a quatifiable and definative definition of AT). A strange combination indeed. While if you look at LT-like terms, you see quatifiable terms (i.e., vis-a-vis blood/respiratory tests) that directly define the Aerobic intensity values (which... like you say... is misleading) when the term "Threshold" is applied.

If I was to try and use the two terms, I think it's better to use intensity values relative to Lactic Threshold as the best indicator of effort applied. And, to some degree this is what AT represents (and, so is the "fat burning" term). The biggest problem with both of these aerobic intensity levels is this - it is not just intensity level that defines them in useful terms... it is also volume associated with the intensity level. This is where the shift between carbo to fats as caloric sources becomes more of a factor.

FWIW Joe Moya

I don't see it as an either/or. Note that aerobic threshold, AeT, ana anaerobic threshold (AT) are completely different. AT is a different way to measure LT. AeT is a completely different intensity.

Both AeT and AT/LT are quantifyable and they quantify optimal intensity for two entirely different types of training. When I'm driving my car in a 25 mph speed limit zone, I try to stay close to that. When I'm in a 65 zone, I base how fast I drive on that. Neither the 25 or the 65 is better than the other; we simply use the appropriate speed limit to manage our driving speed based on where we're driving. In the same way, AeT is the best threshold to use to manage basic endurance workouts and LT is the best threshold to use to manage intensity for tempo workouts.

Using a percentage of LT to estimate AeT is not very accurate. Athletes AeT expressed as a percentage of LT (by HR, VO2, or speed/wattage) vary dramatically. I believe this is due to fiber type differences.

Certainly training volume at each intensity is a critical aspect of race preparation and HR/speed/power at AeT and LT have nothing to do with that. Volume is a seperate aspect of the equation.

Ken

Ken

Wow... this is strange... I was originally going to use the car speed limit analogy.... and, low and behold...ya' pulled that good analogy out for me...

I don't see them as a an either/or except in the situation of how they are applied. Or, as you say - "Aet is best threshold to use to manage basic endurance workouts and LT is the best thrershold to use to mangae intensity for tempo workouts."

What I don't see is this...

Unless AT and LT are analagous, only then (it seems) they are quantifyable and definable in common terms.

Your speed limit example is good and accurate... but, I see it in a slightly different light.

Above OBLA - the speeds highway speeds (Anaerobic)
At or Approaching OBLA - the speed limit becomes highway speeds (i.e., LT).
Below OBLA - the speeds limit are city speeds (Aerobic)

There is only one threshold. This threshold is what is commonly called LT.

Aerobic threshold would be optimal city speeds. While intensities above LT are anerobic and are highway speeds.

And, I strongly agree with the idea that neither training methods (above LT or below LT) have distinct advantages or disadvantages.... they are simply applied in different fashion for different outcomes.

But, when you say that "...using a percentage of LT to estimate Aet is not very accurate. Athletes AeT expressed as a percentage of LT ...vary dramatically. I believe this is due to fiber type differences."

I have one question... isn't fiber types (ratio of ST to FT) genetically determined? If so, then proper training can only improve the efficiency of the muscles ability to produce energy (regardless of fiber types). As a result, wouldn't volume be not so much a seperate aspect... but, rather a co-dependent aspect of intensity? In essense, muscular endurance and aerobic indurance are co-dependent. It seems logical that at higher intensities decreases the ability to increase volume... and, vice versa. This just could be a terminology issue... or, a misunderstanding (on my part) of your statement.

Joe

No, this is exactly what I was trying to convey with my last post. As Ken is trying to describe, there are TWO distinclty different thresholds in regards to what fibers are working and what fuel sources are being used. The confusion comes in that the thresholds biochemically point in different directions. YEs, in one respect, anything below the LT is workign in an aerobic zone, but until you get DOWN to the aerobic threshold, you are still recruiting many fast twitch fibers to help work, you're just not accumulating the lactic acid. Once you get TO the AeT and below, it is all slow twitch fibers, at least in theory.

So the Aerobic Threshold points to all HR below it as working slow twitch muscles. The Anaerobic or Lactate threshold points to all HR above it as accumulating lactic acid (and presumably more & more fast twtich). At HR between the AeT and the AT/LT, there is a mix of both fiber types and increasing amounts of carbs to fats being used.

THat's the way I am interpreting Ken's eplanations, adn that is the deifinition that I was originially seeking and had suspected it beign used that way.

I am satisified that I've got this straight in my head, but yes there is an awful lot of confusion with the term anaerobic threshold being used in different, completely biochemically different ways. Maybe it's time to dig out Streyer's Biochemistry!

My comments imbedded in all caps...

"Wow... this is strange... I was originally going to use the car speed limit analogy.... and, low and behold...ya' pulled that good analogy out for me... "

GREAT MINDS THINK ALIKE!

I don't see them as a an either/or except in the situation of how they are applied. Or, as you say - "Aet is best threshold to use to manage basic endurance workouts and LT is the best thrershold to use to mangae intensity for tempo workouts."

What I don't see is this...

Unless AT and LT are analagous, only then (it seems) they are quantifyable and definable in common terms.

AT IS THE POINT WHERE RQ/RER EXCEED 1.0. IN MY EXPERIENCE, THIS CORRELATES 100% WITH LT, WHICH I DEFINE AS THE HIGHEST INTENSITY AT WHICH LACTATE DOESN'T ACCUMULATE. THIS IS THE INTENSITY AT WHICH, THEORETICALLY, ALL OF THE ST AND FOG FIBERS ARE RECRUITED, BUT NONE OF THE FT FIBERS. fOR WELL TRAINED ATLHETES OF ANY ABILITY LEVEL, THIS FALLS CLODE TO 75 MINUTE RACE PACE.

Your speed limit example is good and accurate... but, I see it in a slightly different light.

Above OBLA - the speeds highway speeds (Anaerobic)
At or Approaching OBLA - the speed limit becomes highway speeds (i.e., LT).
Below OBLA - the speeds limit are city speeds (Aerobic)

WHAT YOU SAY HERE IS CORRECT, BUT OVERSIMPLIFIED. I AGREE WITH THE ABOVE PARAGRAPH IN REGARDS TO ZONE 4 AND 5A TRAINING, BUT AEROBIC THRESHOLD TRAINING OCCURS IN Z2, AT A MUCH EASIER INTENSITY - BASIC ENDURANCE PACE/WATTAGE.

There is only one threshold. This threshold is what is commonly called LT.

I DISAGREE. LT AND ANAEROBIC THRESHOLD ARE THE SAME THING MEASURED 2 DIFFERENT WAYS, BUT AEROBIC THRESHOLD IS A COMPLETELY DIFFERENT MATTER. YOUR THINKING SEEMS TO BE THAT EVERYTHING UNDER LT/AT IS AEROBIC AND THAT IS AN OVERSIMPLIFICATION. EXERCISING AT 70% OF LT AND 90% OF LT ARE VERY DIFFERENT TRAINING. THE FOG FIBERS BEGIN TO BE RECRUITED AT AN INTENSITY FAR BELOW LT/AT. I BELIEVE THAT KNOWING THIS POINT PRECISELY THROUGH LAB TESTING ENABLES AN ATHLETE TO TRAIN MUCH MORE EFFICIENTLY. I'VE HAD A JUNIOR AND AN OVERALL FEMALE WORLD CHAMPION IN THE LAST 3 WEEKS.

Aerobic threshold would be optimal city speeds. While intensities above LT are anerobic and are highway speeds.

And, I strongly agree with the idea that neither training methods (above LT or below LT) have distinct advantages or disadvantages.... they are simply applied in different fashion for different outcomes.

But, when you say that "...using a percentage of LT to estimate Aet is not very accurate. Athletes AeT expressed as a percentage of LT ...vary dramatically. I believe this is due to fiber type differences."

I have one question... isn't fiber types (ratio of ST to FT) genetically determined? If so, then proper training can only improve the efficiency of the muscles ability to produce energy (regardless of fiber types). As a result, wouldn't volume be not so much a seperate aspect... but, rather a co-dependent aspect of intensity? In essense, muscular endurance and aerobic indurance are co-dependent. It seems logical that at higher intensities decreases the ability to increase volume... and, vice versa. This just could be a terminology issue... or, a misunderstanding (on my part) of your statement.

YES, YOU ARE 100% RIGHT. YOU CAN'T MAKE MORE ST FIBERS, BUT KNOWING YOUR AET PRECISELY ALLOWS YOU TO MORE EFFECTIVELY TRAIN THEM. TRAINING AT TOO HIGH AN INTENSITY LIMITS VOLUME AND CAN ALSO REDUCE THEVALUE OF OTHER, HIGHER INTENSITY WORKOUTS. ALSO, FOR IRONMAN DISTANCE ATHLETES, TRAINNG THE BODY TO USE LESS GLYCOGEN AT IRONMAN RACE PACE IS THE SINGLE GREATEST PRIORITY, SO FINDING THE POINT OF MAXIMAL BETA OXIDATION ALLOWS MORE PRECISE SPECIFIC TRAINING FOR THAT GOAL IN ADDITION TO ALLOWING MORE VOLUME.

I BELIEVE THAT ALMOST EVERY ATHLETE DOES BASIC ENDURANCE TRAINING TOO FAST AND THAT DETERMINING THIS LEVEL PRECISELY AND IVING THE ATHLETE OBJECTIVE DATA TO SHOW THEM WHY THEY SHOULD TRAN SO SLOWLY IS AN IMPORTANT PART OF WHAT MAKES ME A SPECIAL COACH.

YOU OBVIOUSLY HAVE A LOT OF KNOWEDGE AND HAVE AN OPEN MIND LOOKING FPOR THE VERY BEST WAYS TO TRAIN. I WISH ALL TRIATHLETES THOUGHT THE WAY YOU DO!!! KEN

Ken, I realize you were probably typign your most recent reply as I was typing mine. In my last post, have I simplified it correctly enough without being too incorrect?

I understand lower zones...what type of distances should I be doing in these zones. For example: What type of mileage for sprint, oly, HIM.

Excellent sunnary AdentureBear.

Ken

"I understand lower zones...what type of distances should I be doing in these zones. For example: What type of mileage for sprint, oly, HIM."

The answer to that is "it depends". The majority of every athlete's training should be in zone 2, but how much that is depends on:
How long you have been in the sport
Your history of injuries
Your personal muscle fiber profile - slow twitchers can handle more hours
Personal limiters
Other prioritites - do you work 60 hours a week and have children?

A good general statement for a relatively experienced athlete would be about 10% more than last year (if training for the same type of events.) Browning and Sleamaker provided some figures for yearly hours for athletes of different levels training for events of different duration in their book Serious Training for Serious Athletes.

Not trying to dodge the question, but everyone is different.

Ken

Ken,

Great answer, I was always under the impression that increasing your run times for example, by 5-10% every few weeks would be sufficient to build a good base. The pace should be meaningless if you stayed in the proper zones. Am I correct, pace should not matter too much in the base building phase?

Then if you have built a good base when should you see improvement in you run times. Should you try and do a 5k TT evert few weeks or months? This is were I have trouble in determining my level of increased fitness.

OK... now I get it...

What you and other's were calling Aerobic Threshold is what I've referrred to as

Sub-Threshold or Sub-functional threshold...

...While leaving Friel's definition of Aerobic threshold in tact (i.e., analogous to LT). * (Side Note: I've actually heard this threshold referred to as the lipolysis threshold/range - don't ask me why I remember that trivial term)

Do you get the feeling that this stuff is starting to sound like the famous "Who's On First? - Skit by Abbott and Costello?

Joe Moya

- Streyer's BioChem... ugh... brings back flash backs simular to Nam. :-)