All About Aerobics: Surveying Our Summer Workouts

Building the Aerobic Engine

In recent weeks we've looked closer at both our warmup and our easier days.  These are each foundational for developing the strength, mobility, and coordination for successful running.  

But there's another key ingredient for successful distance running, and that is aerobic power.  You can get a fuller biology lesson here, but essentially the body relies on three different metabolic systems to generate the energy it needs.  The phosphagen system provides super-short (less than 10 seconds) bursts of maximal power.  The anaerobic (glycolytic) system breaks down stored sugars in the muscles without oxygen for relatively short (less than roughly three minutes) of higher intensity energy.  The aerobic (oxidative) system utilizes oxygen to produce energy, making it slower to both get to work and to stop working.

The three systems work in conjunction, often at the same time.  Depending on the type of exercise, that happens in various percentages of contribution.  In a shorter race like an 800m, the aerobic system typically supplies no more than 60% of the necessary energy.  Double the distance to a mile, and the contribution percentage climbs into the 80s.  At 5000m--our distance of concern--it's risen somewhere near 95%.  And for a marathon, the aerobic system supplies more than 99% of the necessary energy.

What this means is that though less important for the majority of races a high school athlete will see on the track, cross country races require runners to become aerobic monsters.  The good news is that each of the systems can be trained to function more efficiently.  In today's post, we want to look at our Tuesday workout and our Friday long run to see how they help in that regard.

These numbers can fluctuate a bit by source, but these come from Coach Jay Johnson and Altis, both places in the running community I highly trust.

Ready vs Red-Line

Generally our program practices what is called polarized training, meaning our easy days are easy and our hard days are hard.  During the summer, Tuesdays and Fridays are our hard days.  We've already set the record straight on how easy our easy days should be.  But now the question needs to run the opposite direction.  How hard should our hard days be?

While our easy days should be exceptionally easy, our hard days shouldn't be impossibly hard.  There has to be a delicate balance.  One can think of determining the difficulty of a workout like setting the price on a product.  Setting a high price means more profit from each product sold.  That sounds great, so why not jack the price way up?  As well all know firsthand, high prices drive away customers.  The higher the price, the fewer products sold.   Ultimately the goal is cumulative profit.  At a certain point, the increase in profit per product from higher prices is offset by the decrease in sales.  Both low prices with high sales and high prices with low sales are less optimal than competitive prices with sufficient sales. 

As last week's post outlined, hard days need to be challenging enough to generate the sort of training stimulus that requires an athlete's body to adapt and improve.  The adaptations the body makes are like the profits from the hypothetical business above.  Just like low prices would generate lots of sales, the body could handle lots of easy days.  However, the adaptations from each workout would be minimal, as would their overall effect.

At the other end of the spectrum, a super hard workout might ultimately produce a great training response.  However, a single training response--no matter how wonderful--isn't going to generate a ton of progress alone.  Training stimuli need to be properly sequenced to produce a cumulative effect.  The harder the training, the longer the body needs to recover and generate an appropriate adaptation.  Otherwise--as mentioned last week--the body doesn't generate a quality response and stands at much higher risk of injury. 

The body might need 2-3 days to bounce back from a hard day, whereas a super-hard day would require 4-5.  Like high prices lowering sales, the greater recovery time of harder workouts ultimately permits fewer hard days and thus fewer overall training stimuli.  Put simply, the additional benefits of a super-hard day in terms of training stimulus don't outweigh the costs of fewer overall stimuli and greater injury risk.  

Like the business analogy, the goal is to find the sweet spot of workout intensity and quantity to get the greatest cumulative adaptations.  Especially during the summer, that means staying away from the well.  After a Tuesday workout, we want runners ready to go hard again three days later during Friday's long run.  In order for that to happen, they can't be red-lining (going all out).  Instead, runners should be ready at the end of every hard workout this summer to say they could have gone further, faster, or both.  

In the model below, you can see how the literal red line of overtraining leads to a sub-optimal adaptation compared to workouts that back off a little bit.

Tuesday Workouts

The goal of our Tuesday hard workouts is to gradually introduce runners to race efforts and approaches.  This will happen through a series of workouts that will ultimately bridge to our in-season race-pace workouts.  Generally they introduce more and more time at race effort, but unlike the races for the season, they don't get as particular about paces.

Below is a breakdown of the varying Tuesday workouts we'll see this summer:

• Circuits:  Circuits are the gateway into aerobic workouts.  At the start of summer training, they are a fantastic way to get an extended aerobic stimulus and strength training without accumulating too much running volume too soon.   For those with a lower training age and/or less recent running volume, this allows a buildup to more intense running with a greatly reduced risk of injury.  Circuits involve alternations between short segments of running at 5k effort and groups of strength training exercises that keep the heart rate somewhat elevated without additional running.

• Fartlek:  Fartlek is a Swedish word for "speed play".  In general it means a run where the paces intentionally alternate.  Some elite runners--especially in Europe--do versions that might involve a cycle of four or five paces.  Ours will generally only entail two paces.  The purpose for us is to introduce small does of running at 5k effort while keeping the heart rate reasonably elevated during the recovery.  That means the first pace will be 5k effort.  The second will be our long run pace (more about that later).  The most frequent structure of our fartlek will be sets of 2 minutes at 5k effort followed by 3 minutes at long run pace.  The level of the runner will determine the number of sets.  

 

• Inverted Fartlek:  A few fartlek variations will also appear in our program.  As the summer advances, runners will be capable of spending more time at 5k effort and less time in recovery.  This is where the inverted fartlek enters.  Essentially the durations with each set reverse, with 3 minutes at 5k effort and 2 minutes at long run pace.

 

• 30-90 Fartlek:  The final fartlek variation in our program shows up later in the summer.  The length of the cycle drops to only 2 minutes, and the paces become a bit more polarized.  The first 30 seconds is now at goal 5k pace, which is likely faster than current 5k effort.  The next 90 seconds can fluctuate between long run and easy run paces as necessary.  The total volume of these workouts is generally less than a standard fartlek as well, but the number of cycles is still determined by level.  

 

• Progression Run:  One of the primary components of our racing strategy is to finish fastest, but mastering that approach begins in practice.  Progression runs introduce a larger interval of 5k effort running than any of the previous summer workouts,   But rather than oscillating between paces, the 5k effort only happens once at the end.  Before that comes a series of other intervals--each 5 to 10 minutes in length--at slower paces.  The idea is that each interval is a little faster than the previous, such that the the pace progresses from a more comfortable pace down to the 5k effort.  

 

• ​Aerobic Repeats:  Of our Tuesday workouts, aerobic repeats are the ones with the most total time spent at 5k effort.  Like a fartlek, they include cycling through paces.  However, at 4-6 minutes, the lengths of the segments at 5k effort are longer than a typical fartlek, pushing right up to the point at which lactate production begins.  From there,  the pace needs to back off enough to allow the body to regroup, which is a greater demand than a fartlek given the longer segment.  That means slowing down even more to easy pace (or even a jog) for 3 minutes before repeating the cycle.

Every one of our aerobic workouts should end with runners feeling able to do a little bit more.

Going Long

Many programs incorporate a weekly LSD run.  Before anyone freaks out thinking runners are druggies, know that LSD stands for "long slow distance".  For these programs--especially those that run their easy days too fast--the long run is their slowest run of the week.  

However, this generally isn't the approach taken by top runners at the high school, collegiate, and professional levels.  Last week I shared my analysis of easy/recovery paces for some of the elite 5k runners.  While collecting that data, I also looked at paces of their long runs.  The long run pace of the men was consistently 30-45 seconds faster than their easy runs.  The women came in closer to 40-55 seconds faster.  In looking at runners from top high school programs, similar trends emerged.

I've tried to create long run pace recommendations that follow these trends.  However, I also don't think long runs should be run at a constant pace.  Beyond developing endurance, our long runs--like the progression runs mentioned above--reinforce the ability to finish at our fastest.  So while the average pace for our long runs is slightly faster than our easy runs, in practice it's a bit more complicated.  

All of our long runs will be assigned by minutes rather than miles.  Most of them will follow flexible out-and-back routes, where every runner will turn around at the halfway point of their assigned duration, wherever that happens to be on the route.  The big picture goal is to return to the starting point before the end of the run ... if not sooner.  That requires the second half of the run to be faster than the first.  

At the same time, we don't want long runs to become races.  Ideally runners should be able to say at the end of their long run that they could have run ten more minutes and gone slightly faster during that stretch.  To help ensure this, that means starting the long run conservatively, perhaps very close to easy pace.  In the second half of the run after the turnaround, the pace can begin to drop.  To help keep running form intact and prevent a slowdown, the last twenty minutes will include a number of short strides at 5k effort.

The length of the long run will depend on a runner's assigned level but will increase as the summer continues.  However, once racing begins, they will no longer be a weekly occurrence.  They simply take too much of a toll to fit in between races and race-pace workouts.  

Whether it's professional runners like Abby Nichols (10th in the 5000m at the US Championships) or Joe Klecker (4th at the US Championships) or runners at top high school programs like the Herriman boys (1st at NXN) or Mountain Vista girls (3rd at NXN), their long runs fall within the same ranges (relative to their race times) that we will use.

​Finishing Strong

Hopefully this post brings some clarity to how we plan to improve each runner's aerobic engine, but here are a few key highlights:

• Approximately 95% of a the energy for a 5k comes from the aerobic system.
• Hard days should be challenging but shouldn't go to the well.
• Aerobic workouts like fartleks, progression runs, and aerobic repeats help runners get a feel for 5k effort and maintain it late into a run.
• Long runs help build mental, aerobic, and musculoskeletal endurance and should be faster than easy pace without turning into races.

Next week we will look at some of the strength training at the end of each day of training that sustains the ability to do the hard running we've been exploring.