The “burn” analysis tools outlined in the book are commercially available. Click that link if you want to learn about the science behind the method.
At $795, they aren’t cheap but I was curious.
I used the testing protocol during a 20-hour training week to get a look at my “burn” during an average summer loading week.
Links to Part One and Part Two.
My results came back a few days after I mailed off the kit. Here’s a link to the company’s results interpretation page.
Page One didn’t give me much to action.
If you’re interested in body composition data then consider a DEXA scan, rather than doubly labeled water analysis.
In my experience, skin fold measurements will tell athletes what they need to know, and are less emotive than body fat percentages.
Once we are relatively lean, there is more downside, than upside, from cutting weight.
Most every endurance athlete has a desire to be lighter than optimal for performance.
Taking the above into account, the test showed I was “lean enough.”
The next page was the interesting bit.
4,000 kcal a day.
The week measured had:
3 Easy Days, and
4 Loading Days.
Of the 4 Loading Days:
1 was intense
3 were volume focused
At the bottom of Page Two, you can see “Physical Activity Level.”
There is a theory that we are constrained at 2.5x our Basal Metabolic Race.
My experience is 2.5x is not the case. I’ve done hundreds of weeks at 25+ hours of output and can gain weight at high levels of output.
But… as I mentioned in Part One, I fully support the concept of athletes being constrained in different ways.
Constraint, rather than a specific ratio, is what you should be paying attention to.
There will come a point when “more” doesn’t give you any additional performance benefit.
Go past that point, and “more” will make you slower, break you down and significantly reduce the enjoyment you get from exercise.
This breakpoint moves around based on what we have going on in our lives. The wise athlete stays well back from the breakpoint.
When more ceases to work, try less.
Fueling Big Weeks
Our Nutrition Chapter gave you plenty of specifics, and included a section on High Volume Nutrition.
Looking at my 4,000 kcal daily “burn” and…
Thinking back to my elite career when…
My weekly training load was 25-50% higher...
There are a number of things I would have done differently.
First, athletes tend to think in terms of “days.” High-volume endurance athletes should be thinking in terms of weeks.
Intake and output are best matched across a week, rather than a single day.
Ensure we are topped up before our key day.
Fuel across the day.
Fuel after the day, including the following day.
Second, as an elite, I would restrict my intake on low volume days. This was a bad idea.
I was extremely lean and hunger was an important signal I was ignoring. It took energy to ignore the hunger. Energy that would have been better spent helping my body adapt and get faster.
How do you know you might be in energy deficit and under fueled?
John and I wrote you a chapter on The Tired Athlete. Start with my section on Red Flags. From my section:
Watch for:
Ravenous Hunger, particularly for sugar and starch
Night Sweats
Soreness, that doesn’t resolve with a reduction in load
Mood Swings: anger, sadness, despair, euphoria
Low-Grade Injury, especially if it feels better with exercise
Dental Abscesses
Cuts That Don’t Heal
Cold Sores
Elevated Resting Heart Rate
Breathlessness With Light Activity
The warning signals are fed by maladaptive stress.
High Load
Exercise Obsession, “it’s the only time I feel good”
Chronic Energy Deficits
Well before an athlete gets sick they are underperforming due to excessive stress.
Bottom line => we need to fuel our programs.
If you’re dealing with problems in your endocrine system then you are on an unsustainable path.
Finally, if you have a depletion mindset then you’re likely struggling at the end of your big days and long races.
Fueling Big Days & Long Races
~4,000 kcal per day is required to get me through a summer at a Top Amateur level.
Above we discussed managing ourselves across weeks. We could call that aspect Chronic Nutrition.
Chronic Nutrition keeps our bodies stable, allowing us to adapt across our training mesocycles.
There’s another aspect of performance for long course triathletes and ultra endurance athletes.
Big Days
Long Races
These events can be 5 to 8,000 kcal DAYS.
Single-day events require Acute Nutrition.
Acute Nutrition requires rapid uptake to fuel sustained work rates far above baseline.
Many amateur athletes only see this “acute” limiter on race day and blame their nutrition. Nutrition can be the issue but not in the way it appears to the novice.
If we are undertaking a single day event that will push the limits of our ability to fuel ourselves then the first half of that event (at least) is about fueling ourselves, not “racing.”
My recent race report about the Alpe d’Huez Triathlon provides a case study. It was a seven-hour event. Pay attention to my early race pacing and bike fueling.
Single-day fueling capacity also impacts our ability to place back-to-back loading days in our programs.
Bottom Line
With all this stuff:
Nutrition
Output vs Input
Burn Rates
Accuracy is an illusion.
Fortunately, we don’t need precision.
We need:
To be approximately correct over long periods of time. Chronic Nutrition.
The ability to fuel rapid uptake over short periods of time. Acute Nutrition.
Many athletes get the above wrong. In a quest for chronic weigh loss, they seek to minimize input for a given rate of output.
There is a better way. Getting our fueling “right” can give us an edge:
Faster Recovery
An Ability to Absorb More
Superior Late-In-The-Day Performance
Back to Table of Contents
I’ve got a question on fuelling timelines or perhaps dynamics of fuelling over a week, for a low volume swimmer. For arguments sake I assume my BMR is 1800 kcal and I have three sessions in the pool per week where I burn approximately 500 kcal beyond my 1800 kcal BMR. Do I understand you correctly that in the acute perspective, I can fuel 200 kcal extra (2000 kcal) the day prior to my swim, fuel 300 kcal of sports nutrition or food poolside and then my regular 1800 kcal for the day? All based on a long term even base intake around 1800 kcal with the peaks around my sessions.
I’ve got a dexa scheduled for finding my BMR. Asking because I find myself having the mood swings, lack of energy and very poor sleep as you described for under fuelling athletes, although I’m not even close to burning 1500 kcal in my training day. Fuelling for my 3h 10k swim race will be my next challenge.
Thank you for all the advice here!