Hi,can anyone explain the difference between the two and how do you obtain your thresholds.12 weeks out from Cozumel ,following a program that call for bike/run workouts that require vo2 max and lactate thresholds and after some reading am getting confused .Any help or suggested reading would be helpful.
Jimmy
VO2 Max is your maximum rate of oxygen uptake and utilization. It’s not just how much air you breathe but how much get’s pumped via your heart and carried by your red blood cells and then actually utilized by your working muscles. It is limited by several things but mainly by your cardiac output which includes heart rate, heart stroke volume, and the efficiency of your heart as a pump. As VO2 max represents the limit of your O2 utilization at a current point in your fitness training it represents the limit in terms of aerobic production of power. Any power you generate above your p_VO2 Max (aerobically generated power at VO2 Max) must come from anaerobic sources and is not sustainable for long durations. VO2 Max is trainable but not nearly so trainable as LT as described below.
In practical terms if you go as hard as you can for the duration most folks can sustain VO2 max efforts for something in the range of 4 to 6 minutes with some very highly trained folks able to sustain VO2 Max O2 uptake for up to 8 minutes before they have to drop back to lower energy but more sustainable metabolic processes. So in terms of doing VO2 max training it typically consists of repeated near maximal efforts in the 3 to 6 minute range with things like 5 minute VO2 Max intervals being very common. They can be a bit shorter or a bit longer but they must be done very near your maximal effort for the duration and by definition they should get you to maximal breathing and up to or very near max heart rate at least for the later intervals in a set.
LT or Lactate Threshold has a lot of slightly differing formal definitions in exercise physiology circles but the concept is the long term sustainable blood lactate level you can tolerate for longer efforts. It’s correlated (but not identical) to what bike power training folks refer to as FTP (Functional Threshold Power) or the maximum steady state power you can sustain for roughly an hour under ideal conditions (reasonably well rested, well nourished and hydrated, highly motivated like an hour long time trial). So LT is another proxy for what used to be commonly called Anaerobic Threshold (which doesn’t really exist but is another concept describing long term sustainable intensity).
LT intensity is typically around 70% to maybe 85% of VO2 Max intensity for trained athletes but can vary quite a bit. VO2 Max intensity (or p_VO2 Max) may set the aerobic limit but LT intensity (or FTP) is what really counts for sustained endurance events and is more highly trainable though it can take a long time to train. IOW, two athletes both weighing 70 kg could have the same VO2 Max of say 70 ml/kg/min of O2 uptake and utilization and perhaps the same p_VO2 Max of 400 watts. But one could have an FTP that’s 70% of that p_VO2 Max (280 watts sustainable power) and the other could have an FTP that’s 85% of that same p_VO2 Max (340 watts sustainable power). That second athlete is the one you’d want to put your money on for an endurance event.
In practical terms LT efforts can be sustained for an hour or more on a good day with sufficient motivation and focus but typical LT interval efforts are in the range of 10 to 60 minutes or so with things like pairs of 20 minute efforts (2x20s) with limited rest between them being very popular when focusing on LT training. Again these have to be done at near maximal efforts for the duration. If you can run a certain pace for 20 minutes on a very good day then you’d want to run at 90% of that pace or more, or if you can sustain a certain power on the bike for 20 minutes on your best day then you’d want to do your normal day in, day out LT 20 minute intervals at 90% of that power or more.
So basically if you’re not training with power or not training on the bike then the key thing is to choose the duration (3-6 minutes for VO2 Max work, 10 to 60 minutes or say 15 - 30 minutes as more reasonable for LT work) and do them at near maximal intensity for the chosen duration. If it doesn’t get you breathing maximally and get your heart up very close to or up to max heart rate by at least the second or third effort then they’re likely too easy for VO2 Max work. If the LT efforts don’t take a ton of concentration and get you breathing deeply and steadily to the point you couldn’t really hold a conversation and you’re not pretty happy to finish each interval as the final minutes approach then they’re likely a bit easy for good LT work. Conversely if you can’t finish the individual efforts or finish the sets then it’s likely too hard for your current fitness level and you’ll want to back off the pace a bit until you can actually complete the sets.
Hope that helps,
-Dave
Vo2 max-highest effort level aerobically, corresponds to max heart rate
Lactate threshold-could get into the energy system stuff but it is your effort level over the course of an hour.
There are calculators to convert time trial performances in all sports to your threshold values. On the bike do 20 minutes all out and subtract 5% from your normalized power.
I’m sure people will call me an idiot but if you are doing an IM, especially at the level you seem to be, a lot of high end aerobic efforts under your threshold in my opinion are much more valuable than vo2 max work, you’re out there for half a day, you’re not limited by your body’s max ability to deliver oxygen.
Thanks for such detailed info
Much appreciated
Jimmy
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Just to add to the very detailed description above - the most useful definition of LT is quite simply the heart rate at which the amount of lactic acid produced in your muscles is equal to the amount of lactic acid removed through the bloodstream. By that definition, once you exceed your lactate threshold, you would start seeing a significant buildup of lactic acid in your muscles.