VO2 workout question

Hi all, I’m after a little advice and knowledge for a session I did yesterday. Specifically what to change to make the workout better for me and if I’m hitting the right targets.
So I did the Ultimate HIIT workout with 3 sets of 30/15’s, at the end of the first set my HR was at around 154/5, on the next 2 sets I was hitting 163/4, if I was to change it to get the most effect from it would I be better adding an effort at the beginning with a minute gap before the sets, or would I see better results from adding 5 seconds to each effort or upping the watts by 5%. What is the ultimate goal for VO2 efforts to get adaptations…
Thanks all that have made it to this part.

Hi, funny, I just went on a ride and was thinking about how to answer this question… Let’s just say this question can result in a million different opinions. The easiest answer is what is the reason for doing that. I just asked ChatGPT and this is a reasonable answer (see lower on this response).

So in general you are talking about nuanced differences and while someone might sound really smart and give a solid reason why one or the other, this is highly individual and no one really know what is going to work better for you. Enter the workout fully recovered, get a good warmup and I believe if you take a structure approach to slowly increasing intensity or duration then ultimately it does not matter what you do, the difference would be so small and you would never know. If one sounds more fun then the other, take the fun one :slight_smile:

We are strong believers here in the last part of ChatGPT’s answer which is * Progress Gradually: Start with shorter, less intense intervals and gradually increase the duration and intensity as your fitness improves. We (Including my partner and top pro coach) would say pros should take this exact same approach. Start out lighter and gradually increase. I probably did not give you the best answer but it’s our beliefs around here.


VO2 max workouts, also known as maximal oxygen uptake workouts, are designed to improve an athlete’s aerobic capacity and overall cardiovascular fitness. Here are the key reasons behind incorporating VO2 max workouts into a training regimen:

  1. Increase Maximum Oxygen Uptake: VO2 max represents the maximum amount of oxygen your body can utilize during intense exercise. By improving VO2 max, your body becomes more efficient at transporting and using oxygen, which enhances endurance and performance.
  2. Enhance Cardiovascular Efficiency: VO2 max workouts help strengthen the heart and improve the efficiency of the cardiovascular system. This leads to a greater volume of blood being pumped with each heartbeat and more efficient oxygen delivery to working muscles.
  3. Improve Lactate Threshold: High-intensity intervals push the body to work at or near its lactate threshold, which helps to increase the point at which lactate begins to accumulate in the blood. This means you can sustain higher intensities for longer periods before fatigue sets in.
  4. Increase Aerobic Power: VO2 max workouts increase the power and speed you can maintain aerobically. This is particularly beneficial for endurance sports, as it allows for higher sustained speeds.
  5. Enhance Recovery Ability: Regularly performing high-intensity workouts can improve your body’s ability to recover between efforts. This is due to improved blood flow and increased efficiency in clearing metabolic byproducts from the muscles.
  6. Boost Overall Performance: By improving aerobic capacity, lactate threshold, and recovery, VO2 max workouts contribute to overall athletic performance. This is particularly important in sports that require sustained efforts, such as cycling, running, and rowing.

Typical VO2 Max Workouts

VO2 max workouts generally involve high-intensity interval training (HIIT), which includes:

  • Intervals: Short bursts of high-intensity exercise (e.g., 3-5 minutes) at or near your VO2 max, followed by rest or low-intensity periods.
  • Tabata Intervals: Very short, extremely high-intensity intervals (20 seconds on, 10 seconds off) repeated multiple times.
  • Hill Repeats: Running or cycling up a hill at high intensity, then recovering on the way down or on flat ground.
  • Pyramids: Gradually increasing the duration of high-intensity intervals, followed by decreasing them in a pyramid-like structure.

Implementation Tips

  • Progress Gradually: Start with shorter, less intense intervals and gradually increase the duration and intensity as your fitness improves.
  • Monitor Intensity: Use heart rate monitors, power meters, or perceived exertion scales to ensure you are working at the correct intensity.
  • Rest and Recovery: Allow adequate recovery between intervals and ensure proper rest days between VO2 max workouts to prevent overtraining.
  • Periodization: Incorporate VO2 max workouts into your training plan strategically, usually during the build phase leading up to key events or races.

In summary, VO2 max workouts are a critical component of a well-rounded training program aimed at enhancing aerobic capacity, improving cardiovascular efficiency, and boosting overall athletic performance.

@Robert_UCL Robert, what do you think? I think your answer is likely even better than mine, or at least can add value for sure.

Hi Leigh, Coach Robert here.

What you are describing is that you see your heart rate increasing during a 30/15 workout. That is entirely normal. This is a very hard workout to do and heart rate is not the best way to monitor this.

It takes te body some time to respond. Around 30-60 seconds. So when your first 30 sec are over your heart rate will still be rising. But then you take a 15 sec rest. That first rest is just enough to stop the increase and, if you’re in really good shape, might even show a slow decrease.

During the first set the body will fatigue and you will be short on oxygen. After a couple of reps the body realizes that this situation is not going to get better and oxygen demand stays high. Therefore the heart will elevate slightly during the set.

The next set you already start with some fatigue. That is why the heart rate will increase even more.

In general, it will take the body around 3 minutes to reach a steady state. Provided that the effort stays the same. Since the rest is so short, the level of effort stays fairly simular.
However, it is so high that the body builds up oxygen deprivation, free radicals, lactate, and ions. The pain you feel in the legs is not lactate. It is H-ions. We used to believe that it was lactate, but actually, lactate is a byproduct that serves as an energy provider at lower intensities.

So, with this in mind, what should you do?

My first advice is to do this workout as it is. Don’t go harder in earlier reps and don’t go easier in later reps. If you go harder you will burn out to soon. You need those “easier” reps to get to the end. Same as you need the intensity at the end to make the difference.

Follow this routine for 4 weeks, than move on to a different workout. There are many different VO2 max workouts. Al lot of them have different training goals. For the 30/15’s the goal is to build up lactate. The rest is to short to let the body recover.

That is different from 1 minute zone 5 followed by 1 minute of rest. In that workout the aim will be to let you recover just enough before your next effort.

In the end you have to look at what you need in a race. If you’re riding gran fondo’s for fun there is not really a difference. These workouts will build you more power.

If you do short mtb races, you will do short climbs and you want to focus on 1-2 minutes of vo2 power.

If you do road races you might want to get ahead of the peloton and do 4-5 minutes of vo2 power.

For short intervals guiding with a powermeter works better than heart rate.

These intervals are great, but don’t forget you don’t have to bury yourself to do a great workout.

Have lots of fun.

Way better than my answer :slight_smile:

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