Comment from James FitzGerald at Optimum Performance Training

We were fortunate enough to receive an interesting and insightful set of comments from James FitzGerald of Optimum Performance Training (OPT) about our post on the Work Capacity Curve. If you don’t know who James is and what OPT is about you should check them out, they’ve done some amazing work in the health and fitness area and training athletes of every caliber and walk of life. Below is our response to his comments.

First off, thank you for your comments! I’ll try to answer it as best I can (italicized comments are from James).

not sure how in regards to “work” how 1 push up is a score of 3200 and i HSPU is a score of 1500, as well a 2 legged squat scoring 6000 and a pistol on one leg scoring 4000.

So based on our estimates (or what we’ve been able to find in the literature or from other references) work for 1 push-up, in terms of movement of center of mass (COM) is approximately the same as the work for 1 handstand push-up (HSPU). Similarly for 1 vs. 2 leg squat. The values you mentioned represent the total work per round for each movement. (5 HSPU vs 10 Pushups — results in 1500 vs 3200).

to me in just “knowing what it feels like” – there are levers and loading that is NOT included in your explanation of how to determine “work” done in these movements – if its COM and distance covered – this makes sense in measuring those things that can be measured like chin up and thruster (possibly…) –

This is absolutely true, the work calculations we provide do not directly capture this information. Someone may be perfectly capable of doing push-ups, but unable to perform a HSPU. In this case, strictly based on work estimates and no other information, these movements would be deemed “equivalent” in terms of their overall level of difficulty or what they say about a person’s overall ability to do work.

Of course this really isn’t the case. What we would expect (reflected in our analysis of athletes data) is that a person who is capable of performing (more) HSPU’s should, in principle, be able to perform more regular push-ups (or movements involving similar major muscle groups) than a person who is not able to do (or can only do a few) HSPUs. There is definitely a skill/technique component with HSPU’s, so this may not always be the case. However, on average we would expect that the person capable of performing (more) HSPU’s to be able to perform more work faster when HSPU’s or any related movements are involved. So in terms of comparative analysis these things will still play out.

Things like movement difficulty can be directly captured by looking across a population of similar individuals (in terms of height, weight, age, gender) and evaluating the effect of a particular movement on work output/time.

but in running, rowing, double unders, muscle ups, KBS, TGU, power snatch, squat snatch, power clean (or power clean slight squat, power clean full squat, power clean no squat) the movements cannot be simplified into weight over distance as everyone is different and EACH REP is different – therefore the movements if picked cannot be used to estimate “relative” work

I agree, to an extent. Our aim with these types of movements is to obtain a general estimate of work. For example, with the Olympic lifts we can approximate the length of the bar path based on an athlete’s height and use this to estimate work. There is a fair amount of research published on this, and we use this information in our work estimates. That being said, technique is going to play an enormous role. Just because someone is 5’9’’ and weighs 210 lbs doesn’t mean they can move a bar as efficiently or as explosively as Ilya Ilin. Additionally, if you were to take a look at the distribution of limb lengths amongst the population of people who were 5’9’’, Ilya’s would likely be very different. Thus, as before, a person who is able to move more efficiently will be able, in general to do more work faster. So for population based analyses we are able to make statements about how these movements affect an athlete’s performance on a given workout.

As far as some of the other movements you mentioned (and other similar ones), we generally rely on average distance travelled, or pace of the run/row, etc. So, for example, the skill associated with something like double unders is certainly going to play an important role in calculating work output. Someone who is very efficient at this movement may only jump about 2 inches at each skip, by comparison someone who isn’t as efficient may be jumping upwards of a foot (and missing a bunch reps as well). In our calculations of something like this we take the “average” (loosely speaking here) and assume that most people will jump about 6 inches per skip. As above efficiency in movement plays itself out in a person’s ability to complete more work (e.g. more double unders) faster as compared to their peers.

i just simply remember what it took to complete 21 rounds of Mary as my PR, and weeks prior did 32 rds of Cindy – and honestly (of course based on training this can make a difference and I am open to that) – Mary kicked the shit out of me – so if power was SIGNIFICANTLY lower, don’t you think there would be the feeling of less work done over that time of 20 min…

I think that this will vary on an individual-by-individual and workout-by-workout basis (21/32 rounds is just ridiculous by the way :)). I can honestly say the most painful variant Cindy I’ve ever done was back at Sections in 2010, it was with a 20 lbs weight vest (I think)… I can’t remember the exact number of rounds I did but I think it was somewhere around 17 (I’ll try to find my results). At the time my Cindy PR was around 24 rounds. The amount of work for the weighted Cindy is about 225,000 ft-lbs and unweighted is about 300,000 ft-lbs and I have to say I’d take unweighted over weighted any day. My point is that though there is probably a correlation between amount of work done and how painful a workout is, I don’t think that this is necessarily the case across the board.

the chart on lowered work output over time has been around since the 50′s when the milers needed an upgrade in their prescription and the German movement of intervals took precedent – therefore requiring some insight into why someone who sprints for 2 min cannot keep this pace for 20 min – but to argue work within that time frame over time for a chaotic, unknowable system is truly admirable, but very tough to do…

I’d be very interested in reading up about this, if you happen to have any recommendations/ references it’d be greatly appreciated! In terms of modeling the work output over these time durations, yes there is absolutely a great deal variation and noise, both from our estimates of work, as well as the various complexities affecting an athlete’s performance on a given workout on a given day. What we do see is that as an athlete enters more workouts, general and systematic trends begin to appear. It’s these trends that we’re interested in studying and providing feedback on.

I hope these generally answer your questions. We’re always looking for better ways of capturing and analyzing athletes performances and we would love to get your thoughts about any ideas you might have about how to do this. Thank you again!


Site Overview Part 2 – The Work Capacity Curve

The work capacity curve

In our last post we discussed how work output is estimated. Today we will discuss the work capacity chart. Recall that looking at work output vs. time provides the first key step of our analysis for determining your ability to do work over broad time and model domains. But with the large amount of variability among workouts, it can be challenging to gauge what your expected work output should be for specific time and/or modal domains.

This got us thinking…why not use a model that is physically representative of work output intensity over time to estimate expected work? There are a couple of criteria for this model:

  1. It should stay true to the athlete’s data
  2. Given that the level of exertion in a 20-minute workout is going to be less than in a 5-minute workout, the rate at which work output increases over time should begin to slow or plateau. To see exactly what we mean, take a look at the familiar work capacity graph below.

The blue line shows a strictly increasing trend in work output… chances are, unless you’re Chuck Norris or on bath salts this model is going to overestimate your physical capabilities. The red line shows our model which we believe is a more accurate reflection of what happens in practice, i.e. as you move into longer time domains the rate of work output begins to slow.

Expected work output range

Variation in work output is not surprising given that different movements will cause your muscles to fatigue at different rates. For example, handstand push-ups will lead to more rapid muscle fatigue and subsequent failure than bodyweight squats, the result of which is lower rep count and therefore less overall work.  To illustrate let’s compare Mary and Cindy, again using your friendly neighborhood statistician (aka, myself) at 6’1” and 215 lbs.

Mary = 20-minute AMRAP (as many rounds as possible); 1 round = 5 handstand push-ups, 10 alternating single-leg squats, 15 pull-ups

Work Estimate (per movement):

1 hand stand push-up =  300 ft-lbs x 5 =  1,500 ft-lbs

1 alternating single-leg squat (aka pistols) =  400 ft-lbs x 10 = 4,000 ft-lbs

1 pull-up =  575 ft-lbs x 15 = 8,635 ft-lbs

1 round of Mary =  14,135 ft-lbs

My PR for Mary is around 15 or 16 rounds making the total work for Mary fall between 212,025 and 226,160 ft-lbs.

By comparison, Cindy = 20-minute AMRAP; 1 round = 5 pull-ups, 10 push-ups, 15 squats.  If you remember from my last post, the total work estimate for Cindy was 325,350 ft-lbs.

From this example we can see that even though the two workouts take the same amount of time, the total work output is considerably different. Intuitively this makes sense since handstand push-ups, pistols and the volume of pull-ups will tend to result in increased muscle fatigue, lower rep count, and therefore less work.

For this reason, it’s helpful to determine a reasonable range of work output over time, which corresponds to the blue shaded region on the work capacity chart.  The blue region captures the expected variability of your workout data (yellow points) above and below the work capacity curve (this is called a “prediction interval”).  Points falling inside the shaded region are within your expected average range for work output.  Points falling above are outperforming your average and points falling below are underperforming.

In the near future we’ll have an additional feature added to the analytics page providing summaries and analyses of workouts falling within, above, and below the shaded region.  This wraps up our summary of the work capacity curve, in our next post we’ll talk about the fitness score.

Keep training smart!!!

(Mmmm… bacon flowers)