Sunday, June 16, 2019

The Poor Man's Giro : Amateur Science in a GT Mimicry

Early in May, I set out to do something in the name of science. I'd read about the physical demands of grand tour racing in research papers and wondered what that would translate to for an amateur rider who works 5 days a week in a day job.

The idea was simple. I set out to ride roughly 1/8th the daily distances in the 2019 Giro d'Italia. Each ride tried to capture the intent and spirit of the pro rides.

For example, if one day was the ITT, I'd go out and smash a little ITT of my own. If there was a mountain stage, then I'd go out and do some hill repeats (we do not have mountain passes in Abu Dhabi ! ). If the ride called for a flat stage, I'd go out on a 40km ride and end with a "solo sprint".

The challenge was called "Poor Man's Giro". I even created a little flyer for it and shared it on Twitter with the likes of sports analytics guru Alan Couzens and exercise scientist Stephen Seiler. 

All rides were attempted in the searing heat of Abu Dhabi. The rides were supported by nutrition from Secret Training U.A.E.

Fig 1 : Too poor to be a pro and ride a Grand Tour? The Poor Man's challenge is an answer!


Now, I faced a few challenges which I need to declare before we get started. Namely :

1) In addition to my day job, I also coach a running club and so squeezing in rides everyday became a challenge.

2) I went on vacation round about the 20th pro stage so I ended up completing just 18 "stages".

3) A couple of rides had to be done indoors on a Cybex ergometer.

4) I took one rest day more than necessary. It was inevitable. Too busy to squeeze a ride in one or two occasions.

5) My time trial bike was not fitted with a power meter so power output wasn't captured for two TT's.

95% of the rides were done on a Colnago C40 road bike outfitted with a Powertap powermeter to capture the workload. Daily rides were uploaded into Strava and synced with GC to power the analytics.



Data Results

Below is the data from 18 rides. BikeStress is GC's implementation of Training Peak's TSS when they got rid of the "TSS" trademark from their software. TRIMPS have been calculated most likely using zonal points. IsoPower is GC's implementation of TrainingPeak's NP, again after getting rid of trademarked metrics.

Fig 2 : Ride, workload and stress parameters  from each day's ride of the Poor Man's Giro


To add a little bit of extra science to the investigation, daily HR and HRV related parameters were measured using a Faros ECG device hooked up to a Polar H10 chest strap. Protocol followed was 5 min supine-standing orthostatic format.

All the data was analyzed in Kubios to extract the mathematical nature of sympathetic and parasympathetic function. A self coded script threw the data onto a spreadsheet and automatically plotted the variables.



Fig 3 : Sets of plots showing the HR/HRV related parameters for the duration of Poor Man's Giro


Discussion of Results

We understand from the Grand Tours research done by Sanders et.al that the stress associated with a time trial (TT) as a function of distance is the highest among flat (FLAT), semi-mountaineous (SMT) and mountain stages (MT).

The authors find a typical average TT speed of 36.5 +- 12.9 kph, an average power output of 371 W at 177+/ 10 bpm, TRIMPS of 33 +/ 32 AU and a TSS of 62 +/ 32 AU. That translates to a TRIMPS/km = 3.39 +/- 1.39 and a TSS/km = 3.39 +/ 0.17 AU/km.

The table 2 from their research paper is very instructive of the performance parameters across the spectrum of stages. Borrowed and pasted below for quick reference.

Fig 4 : Typical performance characteristics from Grand Tours from Time Trials (TT), Flats (FLAT), semi-mountaineous (SMT) and mountain stages (MT).  


This can be compared to my own ride characteristics from Fig 2.

Time Trials : Agreeing with the research, the RPE associated with a solo TT is high, around 8.5-9. TRIMP points are 62 vs 58 (mine) which translates to a TRIMPS/km of between 4-5. This is the highest among all rided that I attempted.

Flat Stages : Agreeing with the research, the RPE associated with a flat stage is around 5 (pro =5.8). TRIMP points are 298 vs 94 (mine) which tranlates to around 1/3rd the heart related stress mainly due to the reduction in distance attempted.   This translates to a TRIMPS/km of around 2 (pro = 1.55).  Power output is around 137 W average giving an average TSS/km of 2.9-3 (pro = 1.14). I presume pros show a lesser power related stress per km riding such long stages due to the draft effect.

Mountain Stages : The ride done on May 25 is a perfect example of a flat ride ending with several hill repeats to mimic the feel of climbing a mountain. The TSS/km and TRIMPS/km came out to 3.8 and 3 respectively, compared to the pro stats of 1.97 and 2.1 AU/km. So the stress was a bit greater on my part, and I probably intentionally made it that way when thinking about climbing.

Daily Accumulation Rates : For 3 weeks, the accumulation of stress was as follows :

The sum total of TRIMPS gained over 18 stages = 1937 AU = 108 TRIMPS/day.

The same for TSS (aka BikeStress in GC language) = 1386 AU = 77 TSS/day.

Total workload = 6467 KJ, with an accumulation rate = 359 KJ/day.


Daily HR and HRV related fatigue : The days after the hardest rides (TT's and MTs) on 11th, 18th  and 28th May respectively show significant drops in time related HRV parameters such as rMSSD and conversely  high supine resting pulses. 

Although all these parameters showed cyclical variations day in and day out, one standout feature was the steady rise in chronic HRV and the steady drop in chronic resting heart rates over the course of 18 days (chronic = long term).

Infact, the drop in resting heart rate, when compared to similar data from the beginning of year show the difference very clearly. The long term difference seems to be a decrease of around 5 beats/min compared to the period prior to starting this mini challenge.

Fig 5 : Highlighted section showing the supine resting heart rate (daily acute and chronic over 7 days) compared with data from March 2019. 



Conclusion

Keeping with the spirit of amateur scientific investigation, an 18 day grand tour was mimicked during the period of the 2019 Giro d'Italia. Despite the limitations of a decreased work load, the aim of trying and matching atleast 1/8th the distance was more or less accomplished.

From the data. I conclude that heart related fitness parameters improved during those days, which shows the effect of a 108 TRIMPS/day and 77 TSS/day loading pattern. However, the data doesn't show the "delayed" effect of improvement that must have come +1 or +2 weeks after the 3 week training was concluded.

I hope to expand on this research during the period of the Tour de France. If you wish to join me in a Poor Man's TDF, please join !  Let's learn together. I can be found on Twitter.

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1 comment:

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