Flux workouts: Working smarter, not harder.
Going stagnant in your training and/or performances? Looking for a change? Flux workouts may be your missing piece of the puzzle...
WEEKLY WISDOM: FLUX WORKOUTS ARE OVERPOWERED
Flux workouts are a powerful tool for improvement that you should heavily consider implementing for yourself and/or your athletes. Other near-synonymous workout terms you may have heard are in and outs, alternations, natural fartleks, or lactate dynamics. Let’s talk about these lovely workouts…
WHAT DA VINKY IS A FLUX?
Flux workouts, characterized by a bout of higher intensity alternated with a bout of lower intensity, revolve around the modulation of recovery with the intention of improving the bodies ability to both use and flush out lactate. HOLD up, did I just say USE lactate?!
Perhaps that sentence confused you, and it would have confused me about a couple of months back (lol). Turns out, lactate isn’t actually what’s burning up your legs (scientifically known as lactate acidosis)! Rather, it’s the by-products (hydrogen ions) that inevitably come with lactate production which contribute to that fatigue. Funny enough, lactate is actually a fuel source which the body can process and use!!! Thus, these workouts can help your body to better use that free energy which otherwise goes to waste.
Renato Canova, famous Kenya-based running coach who’s developed some of the best athletes in the world, defines them in this way:
Lactate dynamics training is any form of training where lactate production is increased by the intensity of exercise and then alternated with periods of less intense activity. In this way, the muscle fibers learn how to both use and clear the produced lactate during the less intense recoveries.
Importantly, the objective of flux workouts should be to raise the floor and NOT the ceiling from a metabolic perspective. In other words, when it comes to progressing these workouts, it often makes the most sense to not increase the speed of the faster portion but, rather, the slower one. This might sound counterintuitive given the natural urge to want to continuously progress the faster rep. In this way, flux training enables us to think about the whole spectrum of efforts; it’s a less polarized way to think about training than your traditional models.
When designing a flux session, it’s important to not only consider the intensity of the work but the durations. In a discussion had on the Scholar Program Discord channel, Jonathan Marcus, who’s had solid success coaching on the high school, collegiate, and professional levels, made this distinction:
With FLUX, not only is INTENSITY considered but so is DURATION of periods of 1) work, 2) back-off from work, and 3) recovery as time/duration is a form of "pressure"/stress as well.
My interpretation of this is that the work is the faster portions, the back-off from work is the slower portions (e.g. really short rest or a float/steady recovery), and the recovery is time where you’re either doing a walking/standing rest or jogging real easy. For example, say we have this workout:
3-4x(4x400 at 3k pace w/ 30-60" rest) w/ 3' rest between sets
Breaking this down, we have…
The work - The 400-meter repetitions run at 3k pace
The back-off from work - The razor-thin 30-60-second recoveries within sets between repetitions
The recovery - The longer 3-minute rest between sets
Don’t worry, there will be more examples to come!
Let’s bring things home on this concept before going into other details below… On last Friday at 12:30-1:30 PM EDT, I attended a coaching meeting in the Scholar Clubhouse (the Discord group name) hosted by Jonathan Marcus. He made a wonderful analogy to illustrate the benefits of flux training from a metabolic perspective…
Metabolically, all athletes start as flimsy paper towels. With traditional workouts such as mile repeats, there is a steadier stream of water which will cause the paper towel to soak much more quickly with water leaking off of the towel. However, with flux work, water is poured in lower doses incrementally, allowing the paper towel to better soak up the water with less spillage. Eventually, with continued flux work, that athlete will level up from a flimsy paper towel to a hand towel, which can absorb more water with less spillage. Then, the athlete may eventually upgrade to a bath towel, absorbing even more water than the hand towel with even less spillage, and so on, and so on…
You can think of the water as the harder portions of the workout, or the work, where you’re running at a higher intensity. The spillage/leakage represents how much you’re reaching into undesired territories metabolically. If there’s spillage, you’re no longer absorbing the work effectively and it becomes more corrosive to your body. In other words, the less spillage, the better!
Ultimately, the point of this analogy is that flux workouts can help make you a more robust runner. You’ll be able to handle more adversity that comes your way on race day such as fast starts, mid-race surges, and end-of-race finishing kicks, all of which add splashes of water to that towel. Thus, they are great for making you a very well-rounded and consistently high-performing athlete.
APPLICATION: WHEN AND WHERE
Generally speaking, flux workouts can be incorporated at all stages of a training plan, from the base phase to the taper phase, in a variety of settings (track, road, grass). They can also be applied to any race distance, from the 800-meter up to the marathon, although the preferred system varies between the middle distance and long distance events.
More specifically, as explained by Canova, middle distances from the 800-meter to the 1500-meter see more benefit from using short repetitions broken up into multiple sets where you might manipulate the recovery times within and between sets. To give an example, here is one as defined by Canova for an 800-meter specialist with a personal best of 1:44:
3x300 in 42” w/ 30” recovery, 3’ rest,
3x300 in 40” w/ 45” recovery, 3’ rest,
3x300 in 38.5” w/ 2’ recovery, 4’ rest,
3x300 in 37.5” w/ 4’ recovery, 6’ rest,
300 SEND
Moving up to the 3k-5k distances, it is generally good practice to use sets with different distances, the first repetition being the longer one to accumulate lactate and the following one being shorter and faster to work through and use that lactate. An example of this could be…
3-4x(800 at 3k pace or just slower, 2’ rest, 300 at mile pace) w/ 5' rest between sets
That right there is what you call a hard V02 max workout, so don’t be fooled by the low amount of sets and high rest…
When it comes to the 10k all the way up to the marathon, things look a little different but not by much in that, logically, the reps are longer. Additionally, this is where float/steady recoveries are commonly used to clear out lactate. Examples of this can be seen below, so I’ll spare you this time…
WHY YOU SHOULD INCORPORATE FLUX TRAINING
Here is why you should add flux training into the mix:
They are a fun alternative to your standard, basic workouts (e.g. mile repeats) which can help keep you more engaged.
They improve your bodies ability to not only clear lactate but USE that lactate as an energy source.
In other words, towards the end of a race when everyone else is fading from the inevitable lactate acidosis, you’ll be at an advantage since you can better use that lactate as fuel to finish strong despite (likely) feeling like absolute garbage! :)
To a similar point as the above, they improve your robustness (i.e., ability to absorb harder efforts) and consequently, racing ability.
Traditional workouts such as 20-30-minute straight thresholds have their benefits, but they aren’t necessarily as effective in improving lactate clearance and usage when compared to flux workouts.
On the topic of thresholds, this is especially true for flat road/track tempos where your pace has minimal fluctuation (unless you execute pacing poorly). However, if your threshold route has built-in hills / undulation, then it serves the purpose of flux workouts given the uphill portions serve as the faster segments (hills = feel the burn) and the flat/downhill portions serve as the slower segments to flush out the system. But, let’s be real, would you rather run a hilly tempo (ew) or spice things up by alternating, say, four minutes at 5-10 seconds faster than threshold pace with six minutes at 5-10 seconds slower than threshold pace for two to three times?! The latter sounds more fun to me… Granted, that depends on the environment you have to work with. That’s just an example, though. :)
EXAMPLES
Flux workouts can come in many different forms. Here are some examples to get your juices flowing:
1600 at 10k pace, 1600 at threshold, 1200 at 10k pace minus 5-10 seconds or so, 1600 at threshold, 800 at 5k pace, 1600 at threshold, 400 at 3k-mile pace w/ 2-3-minute jogs between reps
That’s right… It’s the Michigan workout, guys!!! You have your faster rep and then the slower mile at threshold/tempo to follow.
3 miles of (30-second 200 => 40-second 200)
You might recognize this… It’s the Steve Prefontaine 30-40 workout, baby!!! Of course, most people can’t do this and so you’ve got to adjust accordingly. For reference, the first 200 was roughly Prefontaine’s 3k pace.
8-10x(1’ at 3k-5k effort => 1’ easy) continuous
A CLASSIC fartlek that does a lot more than you think… Depending on the goal race distance and what direction you want to make adaptations, this can be progressed by…
Increasing the pace/length of the slower portion, AND/OR
Increasing the pace/length of the faster portion, AND/OR
Increasing the number of sets
3x(3 mile at marathon pace => 800 float) continuous
This is a very marathon-specific workout that can fit nicely into a long run workout day. This one in particular would best be done within the last 3-5 weeks of a marathon training block. You would want to start this flux workout as something like 4-5x(1 mile at marathon pace => 800 float) and build it up to the above over time, possibly even going beyond this example to 3x(4 mile at marathon pace => 800 float).
4-6x(800 at 10k pace => 800 steady) continuous
This is a great session which can be used in the 10k up to the marathon, although for the latter I’d lean towards using this later into the base phase as a way to transition to more 10k-paced work.
For the 10k, you might progress by…
Increasing the pace of the faster portion (e.g. to 8k pace), AND/OR
Increasing the length of the faster portion, AND/OR
Increasing the number of sets
5-7x(200 at 5k pace => 800 steady) continuous
This is a 5k-specific flux workout. The goal here could be to build up the 5k pace portion until you’re running a near-equal (or slightly higher) amount of 5k-paced work than the slower, steady section. Alternatively, the goal could be to go in the direction of increasing the speed of the steady portion. This depends on whether the desire is to raise the floor or the ceiling, the former often being the priority as stated earlier.
3x(4x400 at 3k pace [4th rep at mile pace] w/ 45” to 60” rest) w/ 3’ rest between sets
This is a good 3k-to-5k-specific workout where within each set, you’re slowly building up lactate and its byproducts from rep to rep with small windows to clear out some of the lactate while using some of that lactate in the consequent reps. Then, you have the longer rest periods between sets to help flush out more of the lactate before heading into the next set with some still in your system.
Worth noting, though, is that I would lean towards using this as a 5k-specific workout over a 3k-specific one. A workout such as this should emphasize quality over quantity through working on the under-side of race pace, a point made time and time again by Jonathan Marcus in the Scholar Clubhouse.
6x500 alternating 100m at 103% race pace and 100m at 94% race pace w/ 6’ rest between sets
This is a 1500-meter-specific workout taken straight from Renato Canova’s PowerPoint on lactate dynamics training (which I will link at the bottom). He does things a bit differently by referring to paces by their percentage in relation to goal race pace (RP), but all you need to understand is that you’re alternating 100 meters at just faster than RP with 100 meters at a decent bit slower than RP. In this way, each repetition is comprised of 300 meters faster than RP and 200 meters slower than RP, the slower portions serving to clear out some of the lactate (and by-products) that is produced within the body from the faster segments. The six minute recoveries allow the athlete sufficient time to clear out as much nastiness as possible before the next rep, although by the end I’m sure this workout is a bit of a killer. Of course, the simpler route is 6x500 at RP, but you could be getting an extra bang for your buck by approaching things in this way.
There’s some examples for you guys! Hopefully, that helped solidify your understanding of this type of work.
LINKS
Renato Canova’s PowerPoint on lactate dynamics
Renato Canova’s Word document on lactate dynamics
Blog post on Igloi - a master of flux-style training
Hey, you!!! Add flux workouts to your training, or else… I will do nothing. :)
If you have further questions, please ask me of course! See my contact information at the bottom of this post; I would love to help.
Next up on All Things Running… Know when to back off in training.
SUPPORT ME
Follow me on my other media:
If you want personalized coaching and/or training advice, I’d be happy to help. You can email me at jacobreesmontgomery@gmail.com or send me a direct message on Instagram.