Split training in running: essential?
Pedro · 23/08/2019 (mis à jour le 23/08/2023) · 9 min read
You will have probably heard it everywhere, the fractioned training in running is a must! But is it for all runners? When you want to pass a milestone and progress, it's often a necessary step... It's an area that is documented by dozens and dozens of scientific studies. Split sessions are extremely beneficial for progress. And today I'm going to first explain why I'm doing split training. And then we'll move on to the most interesting part: how to train well in a fraction.
Disclaimer: And if you don't recognize yourself in what follows... maybe it's because split training is not for you! You can aim to just have fun by simply doing endurance! Your progress will be limited but in the end, is it really a priority for you?
Split training is hard but it pays off!
To begin with, I wouldn't advise beginners in running to split too quickly, because it's intense and hard on the body. It is better to go gradually before starting this kind of training, which can be traumatic for the body when you are not used to it! But at some point, you will have to think about starting the fractionated one, and this article will help you do that.
Moreover, even for experienced runners, it is important not to abuse the fragmented training. It is very effective but it must be used intelligently to avoid the opposite effect: overtraining, underperformance, injuries.
To discourage you even more from splitting up, you can read the psychology of a splitting session. If you still don't want to go your way, it's because you're ready and motivated to do some split training!
Split training: what is it?
Fractional training is simply the act of training by alternating fast phases and recovery phases. It is a qualitative work that allows to work at high speeds for a long period of time. The split drive allows these high speeds to be linked for a much longer period of time than with continuous running and therefore to progress further.
What do we work with split training?
The interest of split training is multiple. Depending on the type of split session we are going to do, we will be able to work on most of the "qualities" that a runner must have. Without being exhaustive, here is an overview:
1 - The heart muscle becomes bigger, stronger:
It's a big muscle, very enduring. It must therefore be pushed for some time before it gets stronger. Especially if you are a relatively experienced runner! Your heart is used to working at high revs, it will take you a lot to impress it and it will get stronger! Fractional training allows you to work at a high level of intensity without ending up on the hinges at the end of each fraction!
Imagine a 4 x 1000m session at a speed of 3000m. It may be very hard on the spot but you will cover 4000m in total at your 3000m speed! Do you see the trick? Your heart will run at a speed of 3000m for longer than it would be able to do continuously. He will therefore try to adapt to this effort and progress even further!
2 - Leg muscles become more efficient
I used the example of the heart but it's the same principle for your muscles! The difference is that since we are endurance athletes, the leg muscles will not get bigger but will get thinner. Muscles also create their own energy. The split drive allows us to push our "energy creation plants" to the maximum. This sends a message to the body to further improve the "production lines of these factories". The goal: to create energy faster / in greater quantity to meet the need. And above all, to create this energy in the most economical way possible.
3 - Better use of oxygen than breathing
When we run, our lungs will transmit the oxygen we breathe to the muscles. Because oxygen is one of the main tools for creating energy. If the muscle works to be more efficient in using this oxygen, the body must also be more efficient in transmitting this oxygen to it.
The amount of oxygen we breathe is indeed limited! The more you are able to send it to the muscle, the more effective it will be to use it. Once again, fractionated training allows the body to be pushed into its entrenchment and forces it to improve in all areas... including the transport of oxygen to the muscles via the blood!
4 - Our stride becomes more precise, more efficient!
Running is about using the elastic capacities of our body. The goal: to reuse some of the energy lost during the impact on the ground with each stride. If we want to be efficient, this energy is free! The more we are able to have an effective forward bounce, the faster we will go without spending more energy. That's why I praise the work of race technique.
But the short split training is also excellent for working on this. By going fast, we force the body to improve neuro-muscular reactivity, the speed at which our muscles react. The more precise and timely the movements are, the more the stride will be able to use the ground impact to its advantage. And of course, the same goes for our tendons which need to be strongly stimulated to strengthen themselves, short split training is a good way to do it.
3 classic split training sessions
Below I have given you some split training sessions that you can practice. I give them as an example but I will come back to each type of session in detail in other articles! ????
The short fractionated type 30/30
This short split training, also called short VMA, is extremely effective. It consists of a 30-second alternation at a speed slightly higher than its VMA with 30 seconds of slow recovery in fundamental endurance. On this session we work on the Maximum Aerobic Power (MPA). Cardio and breathing are at their best because we run very fast. And the 30-second recovery does not allow you to return to the initial state before leaving. This is voluntary to maximize the effects of the session. There are several ways to do this session:
10 x 30/30 for the beginner or runners in recovery period.
20 to 30 x 30/30 for experienced athletes.
2 to 3 x (10 x 30/30) with recovery 3′ in the middle.
It is a very interesting session but it requires a good command of your pace. It is indeed very easy to finish "cooked" after a few fractions because you left too quickly.
The long VMA: 10 x 600m, 8 x 800, 6 x 1000m, 4 x 1500m...
The long VMA session is also a classic. It is run at a speed between 5km and 10km (depending on the time of the season / shape). We use a recovery of 1'30 between each effort. This is a very useful session because it allows you to maintain an intense effort over a relatively long period of time. Unlike a 30/30 where the total effort will rarely exceed 3km, here we are on the double. However, it cannot be said to be less or more effective than the 30/30. Where we were working on our pure power on the first one, here we are approaching a work of resistance. The two sessions are therefore complementary.
Work at the threshold: 4 x 2000m, 3 x 3000m, 2 x 5000m...
Working at the threshold is a very long and fractional training with little fraction. The goal is to run at half marathon speed if you are under 1h30 on this distance. Otherwise you must run at half-marathon speed minus 5 to 10 seconds / km if you are above this time. The recovery time is 2 to 3 minutes maximum between each fraction. At a pace slightly below the anaerobic threshold, it is difficult to hold the session to the end but very effective. This type of session is a good test to know where our level of fitness is! If you are in good shape, it will look good, if not, think about doing 2000m instead.
Be careful to adapt the split looks!
Very important point not to overdo it and fall into overtraining... When I talk about 5km / 10km / half marathon speed... I'm not necessarily talking about your record over the distance. This is the case when you are in shape in the middle of a specific preparation... But it is not the case all year round. Don't forget to adapt the rhythm to your current form! The feeling you should have must be the same all year round, it is not the speed that is the main indicator. It will evolve with your shape.
Example: For my speed 5 and 10km I can add 5 to 10 seconds per km out of season. And for the half-marathon pace, it's more like 10 to 15 seconds / km more.
The diversity of fractionated training and the notion of fartlek
These three split sessions are really great classics but we must not stop at that. Split training offers infinite possibilities! Not repeating the same sessions all year round is a good thing because otherwise the body gets used to it and progresses less. On the contrary, vary the sessions, so the type of terrain is recommended!
For this reason I love the training divided into fartlek. We run in nature, giving ourselves fractions of the time and we move forward whatever the terrain. We are not necessarily trying to measure speed accurately, but to be in the right working area. My favorite? Pyramid training in fartlek: 1'/2'/3'/3'/4'/3'/2'/2'/1′ . We sweep different gaits, we adapt...
Fartlek means "speed game" in Swedish... Everything is said! Running is a hobby, make it a game in training, it's ideal! I gave you an example of a fartlek session. But you can imagine that the combinations are multiple depending on what you are looking to work on!
The trap of split training: Going too fast!
We've all experienced it at least once! A beginning of the session where you feel in great shape, where you can see that you are a little faster than expected. But we insist because we want to and the legs respond! The second half of the split training usually sets things back and slows down. Bad tactics! The ideal would rather be to have a progressive rhythm throughout the session and that the last fractions (or the last one on a typical 3x3000m session) are the fastest.
Moral of the story: In a split training, you start at the expected pace! Especially not faster! And you can always accelerate slightly in the last quarter of the session if you still have some under your feet. Moreover, it is better to slightly accelerate the rate at which we run during recovery periods than to accelerate during the fraction itself! Less tempting, but still more effective! ????
Split training, yes, but in a reasonable proportion!
As I said earlier, split training is good but not too much is needed! Continuous training, in fundamental endurance, is at least as important. Whether for the proper development of your heart, but also your muscles, and especially not to tire more than necessary. Because fractionated training is still very energy consuming and is hard on the muscles. If you don't pay attention to the dosage, it's very easy to get trapped and fall into overtraining!
The ideal ratio, recognized by all, is at least 70% of your fundamental endurance training for 30% intensity training. If you are like me, you will even see benefits to climb to 80% of fundamental endurance.
Split training and periodization
Fractional training makes progress but it is expensive in terms of energy and wear and tear over time. It is therefore necessary to use it judiciously during the year to enjoy its benefits without falling into overtraining! Management by cycle is to be preferred. You will define one (or more) 4-week period(s) (3 weeks of work, one week of assimilation). In this cycle, you can then focus on a particular sector.
Example: To prepare my objective half-marathon, I focused on aerobic capacity, the specific rhythm of the half-marathon. I did a lot of split training on gaits ranging from 75 to 90% VMA to frame this half-marathon pace. I also did a few sessions of fractionated at a faster pace so that my legs would not forget the speed between 95 and 105% VMA, but only as a reminder shot!
On the contrary, someone who is very enduring, rather accustomed to marathons would perhaps be better off favouring fast fractioned training, from 90 to 100% VMA to reinforce this VMA and be more comfortable at a half-marathon pace that could seem fast to him.
Split training is one of the keys to progress!
All this to say that split training is an exceptional weapon to progress in running, but that everyone must use it differently depending on their strengths and weaknesses, the distances they want to progress over in the long term and their running experience. Starting the run by directly applying yourself to split training is not a good choice.
To use the fractionated product properly, it must be gently tamed. And as your self-awareness evolves, you become more effective. Besides, we never finished learning about ourselves... Because remember that each split workout is different, even if the content of the session is the same! ????
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