In my research for this next set of blog posts, I've found something interesting.
tl;dr:
Brad lost a lot of weight going from trackie (82kg) to GTer (69kg).
Losing weight should lead to a loss in total blood volume (TBV) and therefore total Hgb mass.
A reduction in total Hgb mass should lead to a reduction in absolute power via a reduction in VO2max.
Brad has maintained or increased his absolute power, as evidenced by his flat TT improvements.
Something is not right.
Explanation:
We have asked how it is possible that Wiggins can lose 13kg from 82kg and yet maintain the same absolute power. The naive argument being:
muscles make power,
therefore less muscles = less power.
We even delved into where he lost muscle from: upper body, lower body, how can you tell, how do you control that? How much was fat, how much was muscle?
Physiologists, however, should have jumped right in and said the loss of muscle is mostly irrelevant. Instead Krebs Cycle spent a lot of time banging on about elite rowers losing weight but no power, Brad having fat to lose, there was lots of upper body muscle, etc, etc, blah blah. But that was all a smoke screen (similar to all the imaginary MAOD "discussions" that he and acoggan perpetuated for page after page. Very sneaky).
The weight loss from rowers argument was irrelevant for a number of reasons:
1. the rowers who did not lose power lost little weight
2. the rower who lost the most weight (only 8kg vs Brad's 13kg)
did lose power
3. it contradicts an earlier post of Krebs, where he recounts Cadel Evans losing weight but losing absolute power in the process (discussed later).
Here's an example of Krebs' argument:
Krebs cycle said:
What I believe could have happened in 2009 (not saying it did, but just that the possibility is real) is that compared with 2007 when he was allegedly 77kg and 5% bf (according to Boyer), Wiggins lost 6-7kgs from a combination of upper body muscle mass (3-4kgs), whole body fat mass (1kg), lower back and core (1kg) and lower body (2kgs). Yes, this is a massive bit of speculation here. Maybe he lost 7kgs from lower body muscle and dropped absolute power, but maybe he lost 7kgs from his upper body and lost no power. We don't know so its not worth arguing over or pretending that you do know.
Maybe his absolute power decreased slightly, but his decrease in CdA partially offset that and he maintained velocity, but we are now starting to talk about subtle differences when looking at performance on the flat. Doping produces big, noticable differences, but again, that never happened.
But the discussion of upper vs lower, %bf, yadda yadda is all sophistic - ie "apparently sound but really fallacious" arguing, intended to muddy the discussion, misdirect and generally obfuscate.
Why?
Because the things that matter in generating power, are things like oxygen transport, and oxygen consumption (eg mitochondrial density). Weight of muscle per se doesn't mean a lot at this level, where a rider has been training and racing for years, has his mechanical efficiency sorted, maxed out his VO2max, plasma expansion, etc through intense training and racing, etc, etc, things he would have had to do to be world champion at anything on the track, and even for the autobus he regularly rode in as a pro roadie, just making the time cut.
The impact of the weightloss is not the loss in muscle mass. It's the loss in total blood volume, and subsequent loss in total hemaglobin mass and therefore loss in VO2max.
http://www.ncbi.nlm.nih.gov/pubmed/20335738
Maximal oxygen uptake (VO2max), which, in a way, represents endurance performance, is, according to Fick’s equa-tion, determined by the oxygen supply of the blood and by the oxygen consumption of the skeletal muscle.
Nadler's formula says this:
TBV = 0.3669 * (Ht in m)^3 + 0.03219 * (Wt in kgs) + 0.6041
if we simplify the formula, given changing your height is not easily doable, we have
TBV = K + n x weight
where
K = 0.3669 x (Ht in m)^3 + 0.6041
and n = 0.03219
This formula basically says: if you lose or gain weight, you lose or gain TBV.
"Normal" hematocrit is 42% (~14g/dL). So if you've just lost weight, over time, your body's total hemaglobin mass is going to equalise, leaving you back at 14 g/dL Hgb.
Simplified, TBV is proportional to VO2max, and subsequently absolute power.
And we even have an example, provided by our very good friend, Krebs Cycle, who said:
Krebs cycle said:
It is very difficult to loose [sic] a lot of weight and maintain absolute power. Cadel tried this approach mid way through his world cup mtb career and he went from about 66-67kg down to about 62-63kg over a period of at least 6 months (I think it was more like 8 or 9 though). He lost absolute power but managed to slightly increase w/kg.
Does the Nadler formulae and my hypothesis fit the observation?
Rider: Cadel
Height: 1.74m
Weight: 67kg
Avg Hgb: 14g/dL
Abs power : 400 W (used for illustrative purposes)
TBV @ 67kg: 4.7l
tHgb mass = 14 * 47 = 658g Hgb
Abs power: 400W = .6W / g Hgb
p::w = 400/67 = 6W/kg
TBV @ 62kg: 4.5l
tHgb mass = 14 * 45 = 630g Hgb
Abs power: 382W @ .6W / g Hgb
p::w = 382/62 = 6.17W/kg
His total power goes down a bit (4.5%) but his power to weight increases ~3%. ie he could climb slightly better, but his flat TT would suffer - where power to CdA is the determining factor.
Let's look at Brad now:
Rider: Bradley Wiggins
Height: 1.9m
Weight 1: 82kg
Weight 2: 69kg
Avg Hgb: 14g/dL
Abs power : tP W (left as a variable - apologies for making it look confusing, but the results fall out at the end. Bear with me).
TBV @ 82 kg: 5.7l
tHgb mass = 14 * 57 = 798g Hgb
Abs power: tP Watts = tP / 798 W/g Hgb.
power::weight = tP/82 W/kg
TBV @ 69kg: 5.3l
tHgb mass = 14 * 53 = 742g Hgb
Abs power: tP x 742 / 798W = 93% tP
power::weight = 0.93 x tP / 69 = tP/74 W/kg
So Brad's absolute power would be expected to decrease 7%, but his power:weight would increase 10.8%.
NB: If his original weight for comparison was 77kg, the differences would be ~5.4% decrease in total power, ~5.6% increase in power::weight.
Brad certainly climbed better than he ever has at this Tour, thanks to the improved P:W. Unfortunately, Brad's complete and utter drubbing of everyone in the 2012 Tour de France long TTs & Olympic Games TT would seem to indicate there was not the expected 7% decrease in power.
In fact, given he was at the head of the race, we would expect his performance against other riders to at best remain static, or slightly diminsh, thanks to the wonders of plasma expansion. Instead, we see his TT performances do this:
Stage 9: Chris Froome needs 3% more power to match Wiggins
Stage 19: Chris Froome needs 6% more power to match Wiggins
Stage 9: 10th place needs 13% more power to match Wiggins
Stage 19: 10th place needs 15% more power to match Wiggins
Conclusion: Something isn't right.
Assumptions:
* no significant difference in plasma expansion between Brad being World champion on the track and training and racing as a pro on the road for the 8 years before he has an unexpected 4th at the 2009 Tour de France. Safeish as he lost weight.
* there was sufficient time during the weight loss for blood parameters to stabilise, reaching their original values. Safeish, it happened over a number of months.
* whether an athlete's stable Hgb is 12 or 16 g/dL - it would return to that value. I have used 14g/dL for the calculations merely to provide an example.
* I have used the standard Nadler formulae for TBV. Whether an athlete's TBV follows Nadler's equation exactly or not, their height will not change, and their blood volume definitely will due to weight loss - that phenomenon is not in dispute.
* oxygen consumption remains static. With decreased muscle mass, there remains the distinct possibility that you lose mitochondria in the process, meaning oxygen consumption would also diminish.
* ther factors affecting oxygen consumption (eg thermoregulation) that may improve with muscle loss, are outweighed by the loss in Total Hemaglobin Mass.
* Total Hgb mass correlates well with Total blood volume and Hgb (g/dL) is constant. This is based on the observation of the volume regulating system in action for blood withdrawal and transfusion, namely:
http://www.ncbi.nlm.nih.gov/pubmed/20335738
Blood withdrawal leads to a decrease in [Hb] because of a rapid ex-pansion of plasma volume compensating for the loss of blood
volume and a delayed and slow increase in tHb-mass until the original [Hb] is attained again within 30 d ((22); Figs. 4 and 6,
arrows b and c). In contrast, in blood transfusion studies, the erythropoietic system is suppressed within 21 d after trans-fusion, as indicated by a decrease in reticulocyte count, until the individual [Hb] and tHb-mass is restored
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