You probably have heard of it, but chances are you might not exactly know the meaning of it. To put our cards right on the table, neither do I. We can’t, however, ignore the fact that this so-called type of training is fairly popular. So, what’s up with sweet spot training, what does it exactly entail and what is it good for?

Sweet spot training actually seems to refer to a certain intensity zone. Remember we talked about energy systems in the article “The basics of training“? If not, in short: when you are exercising on a low intensity your body is capable of using mostly fat as its energy source. Up until a certain point you can burn more and more fat when the intensity increases. After this point the carbs take over the primary role as an energy source and the delivery of energy from fat even slows down.

Pattern of energy sources

So, if you take a look at the pattern these two energy sources follow, you’ll see that when the intensity increases, you can see fat somewhat as an inverted U and carbs as an exponential function. So, the point when fat is at its maximum energy delivery, it is on the summit of the inverted U. Just after this point fat is still at a high conversion rate but also carbs are contributing quite a lot to the energy distribution. This range at which both fat and carbs are contributing considerably is called the sweet spot and usually ranges between 85 and 97% of your threshold (FTP).

Sounds smart right? Because when you put it like this, it gives the best bang for your buck. You train both your fat burning system as well as the carbohydrate system. Therefore, it seems you get an endurance training as well as a high intensity training at the same time. Here we have the reason why this type of training is quite popular. It fits the needs of the time crunched athlete who trains for an endurance event without having to train endurance. Great stuff!

Hold on for a minute

I hate to be the one to break it to you, but it doesn’t work like this for multiple reasons. The first one is that the shape of the patterns the energy production of fat and carbs follows is very individual. The summit of the inverted U can lie at 75% of the functional threshold power (FTP) or at 95% for a well-trained pro. Also, the inverted U can look more like a child’s slide or a molehill instead of an Alpine summit. So, finding this actual sweet spot is not as easy as it seems.

Secondly, one can state you train both systems at the same time, but one can easily defend the argument that both systems aren’t trained to its full extend. For an endurance training it’s too intense to sustain the effort for a long time. Therefore, the duration is never long enough to fully replace the benefits of an endurance training. Also, for a high intensity training it’s just not intense enough. Therefore, sweet spot training can actually be considered neither fish nor fowl.

Most research shows a strong advantage of polarised training over training more in this grey area. A training distribution of 80% of the time on a low intensity and 20% on a very high intensity seems to be beneficial over training between 2 and 4 mmol lactate; the sweet spot range. It’s beyond the scope of this article to dive further into polarised training models because there are definitely some side issues and problems defining what polarised is, but it’s an argument that we cannot overlook in this discussion.

So what to do?

To wrap it all up. Is sweet spot an intensity zone you should avoid then? Well that would be unfair. Although research points to another intensity distribution model, I don’t believe sweet spot doesn’t has some positive sides to it. It still contains both a high fat and carbs conversion that makes it an interesting intensity zone, just like any other intensity zone. However, where this sweet spot range should be is very different for every individual and that causes some practical issues in the execution. The real problem with sweet spot workouts is that one can have the idea that these types of workout have same beneficial effects as endurance exercises in a much shorter amount of time. This promise just doesn’t withstand the fact that there are no shortcuts when it comes to training progression.