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Work Capacity, Explained

(Written 3/1/2017 for my first blog - this is a re-post, with permission from the author ;)

Work capacity is a term thrown around all willy-nilly by CrossFitters and others everywhere. Do you know what work capacity refers to and how you can apply the principles to improve your own training? Once you understand the mathing, you are free to take this as far as you desire.

Simply put, work capacity is an amount of physical work performed in any amount of time. At its core, work capacity is a calculation of power (force x distance / time). Traditionally, this formula is used to quantify power during an explosive activity over miliseconds (vertical jump, implement throw, sprint ground contact, olympic weightlifting peak power, etc.). However, we can also look at work capacity beyond the milisecond. For example, work capacity can be quantified for short-term (one working exercise set), mid-range (over multiple sets and reps), and even long and very long-term time domains (over an entire workout’s duration, a week, month, or many years). Would you like to lift more weight in less time? Of course you would!

To take this to the extreme, world-class Olympic lifters need to express degrees of work capacity during competition. Sometimes competitors only have 2 minutes or less between two highly technical and maximally demanding lifts. With all else equal, the fitter athlete (the one with greater work capacity) wins.

Generally, if you want to shed body fat and build muscle, you must increase work capacity. Most of the time, we do this indirectly with our training. If we train for a fixed amount of time each week and get stronger, we will be moving more weight in a fixed time, which yields and increase in work capacity. If you apply the examples from this article, you can learn how to consciously plan and chase work capacity improvements for long-term health and strength.

To make this immediately relatable, let’s take a simple movement like a deadlift and create an example. If I deadlift a 200lb load for 10 reps, I completed 2000lbs of work. This is a general quantification because distance (used to calculate foot-pounds, etc.) and velocity (used to calculate explosive power) are not factored in. If I performed power cleans with the same load for 10 reps, work would be a larger value because the barbell is travelling further.

Back to the deadlift - If those ten reps took me 60 seconds to complete, then my work capacity for that set equals 2000lbs/minute. If I completed that set in 30 seconds, my work capacity is double (2000lbs/30 seconds, which equals 4000lbs/minute) because I completed the same amount of work in half the time. This can be considered acute work capacity because the work is performed over a short duration!

Training examples for increasing acute work capacity with a single movement:

· Perform more reps with the same weight in the same time or faster, acute work capacity increases (for example: 10x200lbs in 20 seconds = 6000lbs/minute)

· Perform the same amount of reps with a heavier weight in the same time, acute work capacity increases (for example: 10x210lbs in 30 seconds = 4200lbs/minute)

· Perform more reps with a lighter weight in the same time or faster, acute work capacity can increase (for example: 15x150lbs in 30 seconds = 4500lbs/minute)

· Perform less reps with a heavier weight in the same time or faster (6 reps with 335lbs in 30 seconds = 4020lbs/minute)

As you can see, there are many ways to increase acute work capacity. If you want help utilizing work capacity to fit your specific goals, message me and I’ll try to help!

Let’s get more complicated. What about multiple sets? Same weight, 200lbs for 5x5 with 60 seconds rest between sets. Let’s assume I’m lifting at the same speed – 10 reps in 30 seconds, or 4000lbs/minute, and that my rep frequency remains constant. Each set will take 15 seconds to complete (5 sets x 15 seconds/set = 75 seconds of lifting time) plus the 4 rest intervals of 60 seconds each (4 rest intervals x 60 seconds = 240 seconds). Add the work time (75 seconds) to the rest time (240 seconds) and you get 315 seconds, which is 5 minutes and 15 seconds, or 5.25 minutes. Now let’s calculate the total work. 5 sets of 5 reps at 200lbs (5x5x200=5,000). So 5000lbs moved in total divided by 5.25 minutes to complete that work (5000/5.25=952). So 952lbs/minute is my average work capacity over those 5 sets. This is significantly less work/minute compared to our inter-set (acute) work capacity of 4000lbs/minute because the rest dilutes the equation.

Training principles for work capacity over multiple sets and reps (hint – eerily similar to acute work capacity):

· Without being redundant, more total work performed in the same amount of time, or the same amount of work performed in less time equates to an increase in work capacity over multiple sets and reps (for example: week 1 – 5x5 at 200lbs in 5 minutes. Week 2 – 5x5 at 200lbs in 4:30. This is an increase in work capacity! Another example: Week 2 – 5x5 at 210lbs in 5 minutes)

Session Work Capacity

Now it’s time to calculate work capacity values for entire workout sessions. For example, if I move 30,000lbs in my Monday workout and it takes me 60 minutes to complete, my average work capacity is 500lbs/minute (500lbs/minute x 60 minutes = 30,000lbs.

Increases in daily work capacity:

· If I complete the same amount of total work in less time, my work capacity increases

· If I complete more total work in the same time, my work capacity increases

Do you see the similarities between daily, inter-set, and acute work capacity? The principle is uniform across the entire training spectrum.

Work Capacity and Training Phases

You can track work capacity over any length of time. To travel further than we’ve already come, imagine if you quantified all the work completed over a week’s time. For example:

Monday – 30,000lbs (in 60 minutes, same example from above) Tuesday – 20,000lbs (in 50 minutes) Wednesday – Rest day Thursday – 45,000lbs (100 total minutes) Friday – Rest day Saturday – 40,000lbs (in 80 minutes) Sunday – Rest day

Weekly total work: 135,000lbs completed in 290 minutes This week’s average work capacity: 465lbs/minute.

Here’s your monthly quantification:

Week 1 – 135,000lbs in 290 minutes (465lbs/minute) Week 2 – 145,000lbs in 330 minutes (439lbs/minute) Week 3 – 152,000lbs in 360 minutes (422lbs/minute) Week 4 – 80,000lbs in 200 minutes (400lbs/minute)

Monthly total work: 512,000lbs completed in 1,180 minutes Month’s average work capacity: 434lbs/minute

Now that we’ve calculated the weekly and monthly average, we can also do a 3-month average, 6-month, 12-month, and multi-year averages. If your work capacity is increasing, then you will be forcing your body to adapt to the increased stimulus. More on this below.

Work Capacity Adaptations

There are many adaptions that accompany improvements in work capacity:

· Fat loss (especially when combined with adequate nutritional lifestyle habits)

· Muscle hypertrophy (through increased mechanical work, or training volume)

· Improvements in localized muscular endurance, metabolic capacity AND cardiorespiratory endurance (due to adaptations in muscle tissue, energy metabolism, and the neuromuscular system)

· Harder to kill (probably. I mean, in some situations, maybe. In a fight to the death between you and your kung foo equal, if you have greater work capacity, you can defeat them…)

So if you want to look good nekid, increase strength, muscle hypertrophy, muscle endurance, and improve your cardiorespiratory output, begin to fill your workouts with opportunities to improve work capacity over daily, weekly, monthly, seasonal, and yearly durations.

As with all training, your adaptations are a direct product of how you train, what you fuel your body with, and how you treat your body, mind, and spirit outside of training. Train for steady increases in work capacity over time, and your body will adapt and reward you with a (hopefully) constant improvement towards your genetic limit.

Thanks for reading! I hope you enjoyed mathing.


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