Threshold question

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To the Wire wrote:

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Do a search. These questions have been done to death here.

I have not been able to find a clear cut answer on the differences. Sources contradict each other via the web. I would like to know from a running and training perspective then a medical one. Thanks!

Here is my take:

1) Aerobic threshold: I know coaches use this, but I cannot say there is a physiological answer. A common definition is something along the lines of where anaerobic metabolism (often measured by lactate concentration) starts, but is below LT. Usually around 2 mmol/L. The intensity is pretty low.

2) Lactate threshold should only be used when one actually measures lactate levels in the blood. The general idea is that anaerobic metabolism begins to contribute to ATP production in a meaningful manner. An aspect of this is when lactate levels rise exponentially or when the production exceeds the body's ability to process the lactate. The issue is that from the physiological perspective, it is more of a concept. Coaches (and athletes) want an operational definition and that can vary. A prof friend looked and found something along the lines of 25 different versions of LT from 4.0 mmol/L (referenced as OBLA--onset of blood lactate accumuluation). There is Dmax, there is the 1 mmol rise above baseline followed by another 1 mmol rise. However, almost all of these correlate well with actual endurance performance.

3) Anaerobic threshold to me should be banished from the lexicon. It implies that there is a point at which one goes from aerobic to anaerobic when both are functioning. These days I seem to see it used for what I learned at ventilatory threshold. The nice thing here is that you can measure this without taking blood, but you need a metabolic cart. A common way is to see when CO2 production increases exponentially or the ratio of CO2 to O2 "breaks". Most met carts can automatically select that "break". There are a few ways of operationally defining VT/AT as well. I here a lot of lay people use anaerobic threshold and lactate threshold interchangeably.

In a great many people LT and VT (AT) will be pretty close to one another in terms of pace or % VO2max. In an untrained person LT/VT can be 50% of VO2max. In a highly trained runner 90% is not unusual to see.

If I remember correctly, Joe Friel says LT is the pace at which you could race a half marathon. You can search his site if interested. You can use Jack Daniels' VDOT charts to find your LT pace. His Interval pace is the best way to train VO2Max according to him, doing 5 minutes or less per work interval. Marathon pace has to be below LT because if you go beyond it you will ruin your whole race. They stay just below it.

aerobic threshold= 70% Vo2 max

lactate threshold= 85-88% vo2 max

anaerobic threshold= 85-88% vo2 max

2mile race= 100% vo2 max

lactate threshold and anaerobic threshold are the same.

how does marathon pace fit in? marathon pace is a daniels thing. gotta read the text. basically it is the anaerobic threshold plus 10-15 sec.

What percentage of vo2 max should each of these be run at? personally id read up on the fractional use of vo2 max and drop the daniels charts. daniels does some great stuff but you gotta make your own decisions not the ones that jack daniels would make.

the aerobic threshold is the point you stop using free fatty acids as your primary fuel source and start using glycogen as your primary fuel source.

the anaerobic (lactate) threshold is the point you stop clearing lactate at the same rate your produce it and it starts accumulating. the lactate would become a hydrogen ion and cause you to slow down.

For the record, even though I referred the OP to Daniels' charts, I don't totally rely on them in training. I go do my own thing and then compare them to the charts wondering if they can predict my next race time.

I do like Joe Friel's training zones though; although except for tempo runs, I wouldn't necessarily rely on them. I pretty much do my set training at a pace according to how I feel and make sure I know the purpose of the workout.

I am glad the OP is thinking about these thresholds. I simply do multi-pace training but if Daniels' is right, there could be a better way of training. I'll worry about that once I stop getting faster and am in search of a new way.

From200mTo8k wrote:

I pretty much do my set training at a pace according to how I feel and make sure I know the purpose of the workout.

This.

If you need to do percentage calculations then you are overthinking it. Know the purpose of your workout and run by feel. If you listen to your body you will begin to know your own thresholds. It will make you a better runner.

To the Wire wrote:

I have not been able to find a clear cut answer on the differences. Sources contradict each other via the web. I would like to know from a running and training perspective then a medical one. Thanks!

Probably on the wrong site to ask this. :)

Get a respected trainer's book. Base it on one of their definitions. Then you won't be confused all the time.

[quote]luv2run wrote:

Here is my take:

2) ....The issue is that from the physiological perspective, it is more of a concept. Coaches (and athletes) want an operational definition and that can vary. A prof friend looked and found something along the lines of 25 different versions of LT from 4.0 mmol/L (referenced as OBLA--onset of blood lactate accumuluation). There is Dmax, there is the 1 mmol rise above baseline followed by another 1 mmol rise. However, almost all of these correlate well with actual endurance performance.....

Training according to lactate is brilliant. I went from 1.59 to 1.50,34 in a year doing lactate. It was the easiest year of training ive ever done, slow and always with low lactate. But it worked.

Can you tell us more about your training that got you down to 1:50?