Thursday 23 May 2013

A reconsideration of a famous Tour de France cyclist's physiology

Yep, the gossip circus surrounding Lance Armstrong is still alive and kicking. No, I am not going to tell you anymore Ophray Winfrey-like stories, we have heard enough of those.

Let's take a more positive (...) approach.

So. Unless you hate sports or have lived under a stone for the last few years, you haven't missed the ongoing doping scandal in road cycling. A few months ago, this reached a climax with the confession of seven-fold Tour de France Champion cyclist Lance Armstrong to have used erythropoietin ('epo'), red blood cell reinfusion, testosterone, cortisone and human growth hormone to enhance endurance performance.


Ever since, the big question is how much this doping has contributed to his great success, including his Tour de France victories? In other words, how good really is Armstrong? What makes him such an excellent athlete, doped or not?

Well, believe it or not, Lance Armstrong's physiological progress has been described in detail in a scientific paper published in the Journal of Applied Physiology in 2005. Researchers from the University of Texas have closely monitored Armstrong's maturation as an elite cyclist and found some interesting results that might answer the questions above.

Lance Armstrong was tested 5 times between 1992 and 1999. Body composition, maximal oxygen uptake, lactate treshold and mechanical efficiency were measured. Since Armstrong was diagnosed and treated for cancer in 1997, but still tested that year, this period of reduced training and recovery was incorporated into the measurements. Most tests were done off-season, though 1 test was done at the end of the race season (no athlete would come in for a scientific test in the middle of the race season).

In the race season of 1993, Lance's VO2max, i.e. the maximum amount of oxygen his body can take up per minute, was ~ 6 L/min. Or, since body mass determines oxygen uptake capacity,  around 80 ml/kg/min. The pre-season measurements were a bit lower, but still around 75 ml/kg/min. Given a strong reduction body weight from pre-season to race season, but an assumingly steady VO2max of 6L, Lance Armstrong's VO2max values during the Tours were estimated to be around 85 ml/kg/min. For comparison, Miguel Indurain, fivefold winner of the Tour, is reported to have values around 80 ml/kg/min.

Armstrong's lactate treshold was, as expected, at the high end of the range, with LT at 76-85% of VO2max. Most unique though, was the low lactate level after maximum effort. While others, including his teammates, had lactate levels of 9-14 mM after exercise, Lance's values were only 6.5-7.5mM. In other words, either lactate production was extremely low, or lactate removal extremely fast.

From Coyle, Journal of Applied Physiology 2005


Showing that he really is human after all, chemotherapy and the concomitant decrease in training volume affected his VO2max. Eight months after chemo, with a training load of about 1-2 hour at moderate intensity per day, VO2max was around 67 ml/kg/min and post-exercise lactate levels were 9.2mM. It must be noted that it is generally thought that people who are not somehow genetically endowed for endurance, can maximally reach 56-62 ml/kg/min - with prolonged and very intense training. In other words, Lance's values after chemo were still higher than the those of a hard training, but untalented, John Doe.

That's a nice bunch of data. What does it tell us about the maturation of such an extraordinary athlete?

Interestingly, VO2max and LT values did not change all that much during Lance's career. What did change, was his mechanical efficiency. Efficiency is the amount of work one can put out for a given amount of energy. It speaks for itself that it is beneficial if one can put out more work (watts) while using the same amount of energy. Well, Lance Armstrong's efficiency increased a mere 8% during his career. When incorporating the race season's weight loss, this increases to 18%.
That's a lot. Think of having to work 8-18% less to bike at the same speed.

What does this have to do with doping? The author of the 2005 paper has now published a reconsideration of their conclusions at that time (in Journal of Applied Physiology May 2013). Would the data have been affected by Lance's doping? Obviously it is hard to tell for sure which, if any, results have been skewed by doping. However, the substances Armstrong has admitted to have used are not known to have any effect on mechanic efficiency. Increased training capacity due to doping can help change lactate treshold and VO2max, but mechanical efficiency is thought to increase due to changes in the amount of slow muscle fibers. That is a long term process that is probably not that easy to change with doping.



In summary, Armstrong's physiological values are well, well above average. His VO2max is amongst the highest every recorded, his blood lactate values are extremely low. However, these values did not change all that much during his maturation as a cyclist. Most of all, his dedication to training has paid off in the form of a remarkable increase in mechanical efficiency.

So, yes, he has used performance-enhancing drugs. There is no excuse for that from many perspectives - as an athlete that is distorting competition, as a leader of his Foundation, as a person per se, even. No one can tell how he would have performed without doping - as we don't know for many in the peloton at that time. But whether you like Armstrong or not, his doping use, his personality or whatever, a big part of his progress can be attributed to a factor that is unlikely to be changed by doping, namely his mechanical efficiency. That makes him a very remarkable athlete after all.


Saturday 18 May 2013

Keep your legs cool (?)

Summer has arrived in Sweden! It triggers thoughts of long lazy evenings in the sun (ergo, easy evening jogs), swimming in the lake (with a wetsuit and 25 other triathletes) and romantic bike rides to the Royal Castle at Drottningholm (me and my bike).

The resulting fully packed training schedule demands a fast recovery between these exercise bouts. Given warmer days now and ahead, I thought it would be interesting to explore the effects of post-exercise cooling on recovery. With the risk of burning my fingers, let me try to shed some light on the most recent findings.

First, it is important to define the exact question I am trying to answer here (will explain later why that is!). So: Does post-exercise cooling of the whole body and/or specific body parts, enhance recovery and thus, improve performance in the next exercise bout?

Let's start with a paper published in PlosOne (Hausswirth et al. Dec 2011). The authors compared recovery after a 10K simulated trail run followed by either whole-body cooling, infrared therapy or passive recovery. Each of the recovery methods was applied 3 times: after 1 hour, after 24 hours and after 48h. Recovery parameters were muscle damage, muscle strength and perceived pain and fatigue. Muscle damage was assessed by measuring an enzyme called creatine kinase (CK) in the blood. CK is an enzyme that you can normally only find in the muscle, but when the muscle cells are damaged by training, the CK flows from the damaged cells into the blood.

Application of either cooling or infrared warmth after 1, 24 and 48h did not result in different CK levels (as compared to passive recovery), but cryotherapy had the greatest effect on limiting the loss of muscle strength and also induced the best results on subjective perception of pain. Ergo, muscle damage was the same, but because subjects felt less pain, they performed better on the strength test.

In this paper, cryotherapy was performed in specially equipped rooms held at extremely low temperatures (-10C, -60C and -110C). This is obviously different from whole-body immersion, let alone topical application of cold (like, an ice-pack). So don't run to your freezer yet!

The attentive reader might have noted that muscle strength is not the same as exercise performance. Important to define when critically evaluating scientific evidence, is the exact nature of the evidence and how that matches with your research question. So, we need some more evidence than muscle strength alone. Especially since muscle damage (i.e. CK levels) seems to be equal after different recovery methods.

A careful search on Pubmed, the online medical journal database, is rather disappointing. Turns out there are not that many studies that actually consider performance. Creatine kinase levels, blood lactate, the level of oxygen in the muscle and blood volume changes might be interesting, but are no guarantee you actually go faster after that ice bath. Coming back to my remark on matching your research question with the scientific evidence - this evidence doesn't answer my question.

I do find some studies that incorporate muscle performance measurements, but I am not sure that any manufacturers of cooling gels or ice packs, are going to like the evidence... An article in The Journal of orthopaedic and sports physical therapy (Stacey et al. Oct 2010) describes sprint performance after either cryotherapy, active recovery or simple rest. Subjects performed 3 x 2-minute sprints, with 20 mins of recovery between each sprint. The subjects reported that their legs felt better after the cryotherapy, but no effect was observed on performance in the sprint after the different methods of recovery.

A paper in the journal Medicine and Science in Sports and Exercise (De Pauw, May 2011) did not find any effect of cooling or active recovery (versus rest) on performance in a 30-min time trial, either.

It must be noted that in both of these studies, the time between the exercise (the one you need to recover from) and the performance measurement, was rather short - 20 minutes to 2 hours. 'Normal' athletes like you and me usually take more time in between trainings and the limited recovery time might make it difficult to pick up small differences between the methods.

Given that the ultimate aim is to improve recovery and thus, long-term training effect, I was interested in a paper I found in the European Journal of Applied Physiology, where cryotherapy was incorporated in a training program (Yamane et al., 2006). Again, the evidence is rather disappointing, if not disturbing. In this study, subjects underwent a 4 or 6 week endurance cycling training program. After each exercise bout, one of their legs was immersed in cold water for 2x20mins, while the other leg did not undergo any treatment. After the training program, the subjects performed a bike test with one leg at the time, thus looking at the increase in endurance capacity of each leg separately. They also measured the diameter of the arteries in the leg. More and wider arteries are a known effect of training, as more blood vessels can transport more blood, thus more oxygen

While both legs were trained equally hard, training effects were greater in the leg that had NOT been cooled. Also, the increase in vessel diameter was larger in the control leg. Thus, the uncooled leg actually had greater training adaptations! Th only problem I can find with this study, is that the training program was not that hard, questionning the extent of actual muscle damage.

This lack of effect of post-exercise cooling might not be as surprising as it seems. To achieve adaptation to training, you need a stimulus. If you take too much of that stimulus away, by extremer recovery methods, you might not get all the benefits of your training. On the other hand it's of course not beneficial either, if you are too sore to train, and you have to skip a training. In the end, the only training that makes you stronger, is the one that you actually do...

A side note: This data applies only to the effects of cryotherapy on training and says nothing about the effect of icing on sports injuries. In addition, it does not apply to the effects of pre-cooling on training in extreme heat. 

So. Ice after training? Well, I cannot find scientific evidence that whole-body or muscle-specific cooling has any effect on muscle performance. There are some studies that show improved muscle oxygen levels, or lower blood lactate, but these might actually be detrimental for long-term training adaptations. Subjects reported feeling better after cooling, though. That might be an interesting perspective, given the importance of motivation on training.

What does that mean for you, as an athlete? First of all, it is important that you balance your hard trainings with easy sessions, thus preventing extensive muscle damage and giving your muscles time to recover - and consequently, supercompensate. If you feel you benefit from cooling your muscles after training, you could try turning ending your post-exercise shower with some cold water on your legs. You might feel better, but the physiological effect is probably not as big as you might hope.

PS Like this post? Don't worry, it's okay to share it on FB...

Friday 10 May 2013

Why you should run that last interval

Last Tuesday it was time for another happy interval training with Running Sweden, where I run as one of their coaches. Run happy is their motto and they certainly live up to it - which is why I love being a coach for them. Training consisted of a 5K warmup followed by 6-10x 800m on the track. I like the track because it reminds me of my time as a junior at the athletics club. Needless to say I wasn't particularly good at the high jump, but I have good memories of racing around the track like there was no tomorrow, then lying down on the sun-heated tartan and chat with friends until our trainer forced us to do a proper cooldown...


In 'my' group, we decided to go for 8 intervals. We would go out on a 4min10sec pace (per km) and try to run each next interval faster than that. Said and done. First at 4.03 pace (wow!), then at 4.01. 3.55-3.52. Halfway. Great times thus far, much better than expected, but needless to say it didn't get easier. The last 4 intervals went at 3.51, 3.49, 3.46 and 3.45. Then we faced a tough decision. One more or go home?
 
I have thought about this often. If the training is set at 8 intervals, why would you do nine? Or even, why not just stop after 7?
 
Here is a thought that came up in my mind this Tuesday evening on the track.
 
As a researcher at Karolinska Institutet, my colleagues and I studied the effects of spinal cord injury on skeletal muscle. Due to traffic accidents or falls from great heights, the participants in this study became completely paralysed from the level where the spinal cord got damaged. In the case of our cohort, that often meant that they were paralysed from the neck down.
 
This paralysis obviously has detrimental effects on the muscles that are no longer receiving signals through the nerves. It is not just that the muscle mass diminishes (a process called atrophy, see picture) - the quality of the muscle that remains, also deteriorates. Among other things, the muscle loses its slow muscle fibers and the amount of oxidative enzymes decreases. This causes the muscle to become less resistant to fatigue. Basically it is the exact opposite of what 'we', as athletes, try to accomplish. It doesn't only have consequences on the muscle. These changes in muscle make that the muscle can store less glucose (in the form of glycogen). This glucose instead stays in the blood circulation and goes on to damage other organs. In the end these elevated blood glucose levels can lead to diabetes and cardiovascular disease.
 
MRI image of the cross-section of theupper legs of a healthy subject (upper picture) and a subject with spinal cord injury. The dark matter is muscle, the white matter is fat.




But, most of all, these persons - most of them young and in the prime of their life - cannot walk, let alone run. Have you ever pictured your life in a wheelchair? Would you be able to enter your appartment building without any problem? Your favourite store? Your friend's house? Probably not.
 

So. Why you should run that last interval? Because you can.


Thursday 2 May 2013

When should you drink your protein shake(s)?

You do strength training to get stronger. That means your muscles need more, well, 'muscle', or myofibrillar (myo= muscle, fibril = small fiber) proteins. Not surprisingly, you need to eat more protein to help your muscle. It has been shown that intake of protein rather than glucose only helps in building these myofibrillar proteins. But when exactly should you drink your protein shake(s)?

A study published today in the renowned Journal of Physiology might give some answers.

Researchers compared different nutritional strategies after a bout of resistance exercise. Subjects performed resistance exercise and then got 80 grams of protein over the next 12 hour recovery period.

Some got these 80 grams as 2x40grams (i.e. every 6 hours), others as 4x20grams (i.e. every 3 hours) and others in 8x10gram (i.e. every 1.5 hours).

In this study, researchers found that intake of 20g of protein every 3 hours has the largest effect on muscle protein synthesis as compared to 10 grams every 1.5hour or 40 grams every 6 hours.

So rather than eating a lot directly after exercise, you might want to consider spreading your intake over smaller portions, but eating them more often - though not too often. The optimum seems to be around 3 hours.Think about that next time you have been to the gym!

http://jp.physoc.org/content/591/9/2319.abstract?etoc