What if you could take a physiological test that would say with certainty how you should train? We're not quite there yet, but there are several tests that can help you learn about your specific needs.

It’s the triathlete dream: Being able to know exactly what type of training, nutrition, and taper are perfectly suited for you as an individual—without having to guess via messy trial and error. What if you could simply take a physiological test that would say with certainty you’re a low-volume, high-intensity, fat-fueled, short taper athlete? Unfortunately, the tests for athletes aren’t quite there yet.

“Even though there are genetic tests out there [that recommend training regimens], it’s shoddy science at best,” said Nanci Guest, a Ph.D. and consultant for Nutrigenomix Inc, who does research on genetic nutritional testing and advises athletes.

There are tests that can tell you if you make a lot of fast-muscle fibers or how well you use oxygen. There are tests that can tell you if you share similar genetic characteristics with world-class athletes. There are tests that show common markers among top athletes. But there’s no legitimate scientific test to say based on your genetics or your physiological profile, you should do ‘x’ specific type of training.

But we are getting closer. “It’s around the corner,” said Guest, maybe three to four years.

And in the meantime, there are some tests we do have, especially when it comes to your physiology and nutrition. And there are ways to scientifically know what might work best for you and what won’t.

“That concierge service is becoming available to the weekend warrior,” said coach Carl Valle, who uses high-level performance science for his athletes, mostly track sprinters.

What he means is that elite Olympic-level athletes have had their hands on some fancy testing for years—muscle biopsies, VO2 max tests with respirators, genetic write-ups. Now, though, some of those are becoming available to the masses.

A lot of what you can buy, though, isn’t necessarily going to make you faster, and it’s not always from the most legitimate sources. How do you know what tests you can use to craft the perfect individualized program? And where should you start? Try one of these tests for athletes.

1. Blood Tests for Athletes

Both Valle and Katie Mark recommend their athletes start with a blood test. “That’s your nutritional status,” said Mark, a sports performance nutritionist. A blood test can show you if there are any glaring mistakes or obvious deficiencies you should address. It can also give you a metric to check on over time—if you have an expert who can read it well and tell you how to apply what you’re learning.

2. Body Composition

You don’t need to do a muscle fiber analysis necessarily, but Valle does have his athletes do a body composition analysis with a DEXA scan. That tells you more than just a certain percentage of body fat versus muscle. It also shows you how muscle is distributed and if there are any asymmetries or weaknesses.

3. Metabolic Tests for Athletes

The next thing Mark has her athletes do is metabolic testing, but not just the old-fashioned kind to establish a VO2 max. She also wants to see how they’re using calories at different intensities, what percentage is coming from fat stores v. carbohydrates. And she wants to see this in the field, which is why she has a portable metabolic testing system she uses with athletes while they do time trials on the road or tests sets in the pool.

4. Basic Power/VO2 Max Testing

That doesn’t mean you shouldn’t also do some basic VO2 max and power tests. Those can also let you know where you’re weak and what you need to work on. For example, jump tests measure explosive power; time trials measure sport-specific endurance. “Anything that feeds into performance can be a test,” said Valle. These are also the kind of tests for athletes you would do repeatedly throughout the season to see if the training is working and how.

5. Nutrigenomics Tests for Athletes

This evolving field of study is what Guest primarily works on and is something Mark recommends to her clients as well. With a simple DNA sample, you get a genetic nutritional write-up that might help provide guidance. For instance, you could find out if you’re at risk for low iron or if you’re one of the people who can’t convert as much inactive Vitamin D into the active form. Guest has also done innovative research on caffeine, and found about 10% of people genetically perform worse off caffeine. Knowing this kind of thing can clearly help in triathlon. “If you’re healthier, you’re going to be a better athlete,” said Guest.

6. Fitness v. Fatigue

Now after all your hard work, you don’t want to mess it all up in the last few weeks. That’s where balancing fitness and fatigue—also known as tapering—comes in. Iñigo Mujika is one the premier experts on tapering and can create mathematical models to determine individual tapers for swimmers. Ideally, when you’re ready to go your resting cortisol gets lower and at max efforts your peak blood lactate gets higher. If you don’t have those metrics, simply tracking your resting heart rate at the beginning of the day can show a lot. (That’s not just true doing taper, but throughout the whole season.) There are also studies that show the rate of perceived exertion to heart rate should also drop—meaning you should be able to go faster with what feels like less effort. But don’t get too in your head about it. “It’s very important not to over-react,” said Mujika. Tapering can leave you feel great one day and terrible the next. That’s why solid hard data is helpful.

Remember, though, the test is only as good as the tester, testee, and test equipment. “Otherwise you’re just wasting your time and money,” said Mark.

Mark said she’s seen a number of times where the equipment isn’t even calibrated and the results are applied incorrectly in the real world. That could have huge consequences if, for instance, the test says you need more carbohydrates than you actually do, you try to follow those guidelines, and then you end up with GI distress in a race.

Some find that the results of these tests for athletes simply don’t match up with what they experience, or they still want to make sure it adds up via trial and error. Just use more scientific trial and error—and know there is no one right answer.

“There could be many roads to Rome,” said Valle.