Gut feeling

We have not one, but two brains. Look down for the second one. Yes, your gut. An organ system that is both fascinating and annoying at the same time - who doesn't recognise the slowly emerging feeling that the course of your long run will need to include a portable toilet? Or that your stomach refuses to take in one more gel? You're certainly not alone -  in long-distance events, prevalence of gastrointestinal (GI) distress is thought to affect 30-50% of participants, and up to 93% of long-distance triathletes.

From top to bottom - the gastrointestinal system.

That second brain, however fascinating, is one of the reasons for the well-known gastrointestinal (GI) problems athletes encounter. This time I'll explain why, what other causes for GI problems exist, and what you can do to prevent that ‘breaking the wind’ no longer means your training buddies are happy to draft off you.

The 'second brain' refers to a special complex of nerves in the lining of the gut, called the enteric nervous system. It is connected with the brain through the autonomous nervous system, the part of our nervous system that we have no conscious control over and that, amongst others, makes sure our inner organs exchange information with our brain.

The gut is not only controlled by the brain, but - and this is so special about the enteric nerve complex - it also controls itself, via reflexes. Signals also travel from the gut up to the brain, telling it how it’s doing. To make matters even more complex, different hormones from the blood can influence the gut – and even the gut itself excretes hormones into the blood, giving other organs a status update. All signals can both be stimulatory (increasing gut activity) or inhibitory (slowing down gut activity).

Yes, it’s complicated. No wonder the gut reacts to emotions. Good when it comes to butterflies before competition (or when in love) – bad when the gut turns ‘angry’.

Nervous control of the gut not only by the brain, but also by the gut itself (blue dots are markers for the enteric nervous system).

So how does that relate to GI problems before, during or after exercise and in particular, races?

Before a race, the mental excitement and anticipation of competition can trigger the whole autonomous nervous system, including the nerves to the gut. An excess of stimulatory signals to the gut can cause 'urgency', cramps or even diarrhea.

During exercise, there are many different factors at play:

Reduced blood flow

The main physiological cause of GI problems is thought to be a reduced blood flow to the gut, also called splanchnic hypoperfusion. Strenuous exercise causes the release of noradrenalin from the gut's nervous system, causing constriction of the gut's blood vessels. This  redistribution of blood flow, away from the digestive organs and to the organs that need oxygen and energy the most (=muscles, heart, brain), decreases blood flow in the intestinal system by 20-50%. As the gut's cells also need blood, oxygen and nutrients, this hypoperfusion can result in gut cells being damaged. With damaged cells, the barrier function of the GI tract is compromised, making it easier for bacteria and other potentially harmful bugs to move from the gut into the bloodstream (this, by the way, might be one of the many explanations for being more sensitive to illness directly following intensive training).

Also, absorption and digestion of nutrients from the gut is more difficult when blood flow is restricted and cells are damaged. It is not hard to imagine that poor absorption and digestion of food can lead to abdominal pain, cramps and diarrhea - though it must be noted that hard evidence and full understanding of the problems is still lacking.

Mechanical trauma

The repetitive high-impact 'jostling' of the gut during running is another physiological cause for GI distress. The bumping movement of running mechanically increases the gut’s contractions, pushing food faster through the gut. In combination with the hypoperfusion I mentioned above, food pushes through the gut fast and without proper absorption or digestion. The mechanical stress can also damage the gut cells, even leading to intestinal bleeding.

There seems to be an effect of posture in itself, too. On the bike complaints are, in contrast to running, often more limited to the upper gastrointestinal tract. This is likely due to the increased pressure on the abdomen.

Upper versus lower abdominal problems. From Oliviera and Jeukendrup, SSE, 2013.

Nutrition

A wrong choice of nutrition can trigger or exacerbate problems. Some are obvious, others aren't.

Food items high in fiber, fat, protein and fructose are known to induce GI problems. So are hypertonic sport drinks. Lactose-containing dairy is another common pitfall, as even mild lactose intolerance can trigger GI irritation and distress. Probiotics, dairy products that contain extra bacteria, might cause bloating and diarrhea, so these are best avoided the days prior to competition. The timing of caffeine intake deserves some special attention too, as one needs to carefully balance its mental effects with its toilet effects. Adequate fluid intake is important, as severe dehydration decreases blood volume and rises core temperature, which hampers nutrient absorption and affects GI motility, respectively. Intolerance to food components, such as lactose, gluten or milk protein, are sure to make you run for the bathroom as well.

Other

A (worrying) number of athletes use pain killers such as NSAIDs (ibuprofen, naproxen, aspirin) to relieve existing or anticipated pain, which are thought to increase the risk of upper GI complications.

After a race, the damage done to the gut cells might trigger intestinal bleeding. Though not uncommon, it is not unharmful. Amongst others, the damaged cells let bacteria and other harmful components slip into the blood stream easier, and your immune system will have a hard time fighting these off - energy that is better spent on recovery.

Though there is currently limited scientific evidence to support these guidelines, the following might help you run to the finish line rather than the toilet:

- Avoid dairy products and foods high in fiber, protein, lactose and fat 24-48 hours before competition. Dairy products can be exchanged for alternatives such as lactose-free milk, soy-, almond- or rice-milk. Artificial sweeteners can have a laxative effect, too.

- Stay well hydrated. Start the training or race well-hydrated and ensure an adequate intake of fluid during exercise. In a triathlon, make full use of the tummy-friendly bike leg to drink sufficient amounts of sports drinks (never just water) to replenish the fluids lost by sweat and evaporation and load up for the run. Remember that the rapid evaporation of sweat by riding wind (even a mild breeze) might mask fluid loss rates!

- Avoid sport drinks with only fructose as fructose is not as easily absorbed by the gut. The combination of glucose and fructose does not seem to elicit any problems, on the other hand.

- Avoid hypertonic drinks (pre/during/post exercise). Here, it is about finding the right balance between energy supply, liquid intake and osmolarity. A low concentrated sport drink has low osmolality and is less likely to trigger GI distress, but also has low energy and sodium content. (For those who wish to refresh their memory from biology and physics class ages ago - osmolarity is a measure for the number of particles in liquid. (Over)simplified, it’s a measure of how concentrated the sports drink is. A sports drink that is hypertonic means its osmolarity is higher than in your blood, whereas a hypotonic drink has an osmolarity lower than your blood. Thus, you can determine the osmolarity of the drink itself by making it more or less concentrated)

- A history of GI problems is a risk factor for more problems. If you know you are sensitive (and you wouldn't be the only one), take the time to figure out what works best for you.

- Make sure you are properly trained for the race. The higher the relative intensity, the more restricted blood flow to the gut will be. Things go from bad to worse once you end up in a down-ward spiral of feeling nauseous, having side aches or diarrhea, and not being unable to drink and eat as a result of that. Low blood sugar (hypoglycemia), dehydration and severe damage to your gut cells are all possible consequences that are best avoided.

- There is a scientific debate whether one can actually 'train' the gut to be less sensitive. Some say you can, others say you can't. In effect, it does no harm to practice new nutrition strategies many times before race day to determine what does or doesn't work. Get used to the brand of sports nutrition that the organisation of the race will give you on race day. Determine fluid loss rates by weighing before and after hard training sessions in a climate comparable to the expected race weather, and make sure you don't lose more than 2% of your body weight.

- So obvious it is easily forgotten: When travelling to foreign races, postpone experimenting with the local cuisine to after the race and pay extra attention to the freshness and ingredients of food. If you can't read the ingredients list of an unknown product, don't eat it. Don't show your cultural awareness by eating sausages with undefined content, prepared with an unknown level of hygiene and predictable level of bacteria. Be careful drinking water from the tap - the water may be pure and bacteriafree but high levels of chlorine can also upset your stomach. Choose your restaurant with your eyes, nose and brain rather than your stomach.

All this said, some level of GI discomfort seems unavoidable, given the fact that even well-trained, well-prepared elite athletes often experience problems. However, regular heavy damage to the gut should be certainly be avoided as it might make the gut more sensitive to food intolerances during every day life. The gut is a fascinating organ, but when it's not happy, nobody is happy.

Me, my coach and I

It's been midsummer, when did that happen? Half of the race season is already gone. I currently have less races planned than races completed.

Time for a summary, a recap, an evaluation and a meeting with the coach.

Coach Hanneke: So how do you feel your season has been so far?

Athlete Hanneke: Pretty good actually. I have felt in good shape and have finished all my races at the podium. At first I thought it wasn't me, just different competition. That was partially the case, for example in Hallstahammer the girls that won last year were at some national series/championships. Also, as a science geek, I calculated the relative difference between my time and that of the winner of the men's competition this year and last year and compared these.

Coach Hanneke: And you were relatively better than last year?

Athlete Hanneke: Yes. I was between 2% (Sövde) and 9% (Hallsta) faster than last year. I was actually quite surprised. Hadn't expected that with all the stress of starting my own company, some funny job interviews at the other side of the world or with professors that live IN the university.

Coach Hanneke: IN the university?

Athlete Hanneke: Yes, I thought it was strange, too. On the other hand, some athletes have their bikes in their bedroom...that's more or less the same, isn't it?

Coach Hanneke: I am sure not everything has been perfect so far. What were you not happy with?

Athlete Hanneke: I was disappointed with my competition spirit in Brottby duathlon. I just let the girl before me go. I really should have pushed harder but I just didn't even try. Also, in Sövde, I got a bit dehydrated. I had drunk about 1.5L during the bike and that was clearly not enough. I just never tried my nutrition for a long race. Not smart to think it's just to extrapolate whatever I take in during an Olympic distance. This is what I looked like afterwards:

Coach Hanneke: Indeed, some points to consider there. On the one hand, remember what your first coach, Jean Herpers, has always told you: you can only push yourself to your outer limits in 2 or 3 races a year. The rest is just training. If it's a B-race, then treat it as such and don't be disappointed if things don't go as planned. On the other hand, you need to train your race mentality. What do you feel and think when a competitor passes you?

Athlete Hanneke: I guess I just give up, since they pass me they must be stronger, why else would they pass me. Maybe I should believe a bit more in my strength. That worked in Kilsbergen.

Coach Hanneke: Any injuries?

Athlete Hanneke: I don't think I will ever be an elegant runner. Did you see that picture of me in the final lap at Sövde? That ain't pretty, I can tell ya! I have had some problems with a painful left foot and lower leg. My calves have been sore a lot. But nothing that stopped me from running completely. Maybe I pushed it a bit too far once or twice. But then I took it easy for a few weeks, iced the sore foot/leg and ran 1x instead of 2x per week. Oh and I also did lots and lots of (pre)hab strength exercises. And had massages, at least once every 3 weeks.

Coach Hanneke: Apart from the running technique, sounds like you don't need me to coach you.

Athlete Hanneke: Well yes, sometimes I have the strange feeling that I should be able to coach myself...

Coach Hanneke: You think so? Anyways. What's next?

Athlete Hanneke: I want to do more off-road races. I was looking for a change, those boundaries have been lying there long enough now. But I don't want to do an Ironman (yet, though it's getting itchy..). So I thought, why not go back to my roots, mountainbiking? It's more play, more fun, less serious. I need that smile on my face... And did I tel you I bought a new MTB? So I signed up for the Beach Challenge in Kijkduin in July, and the National (Dutch) Championships Off-road Triathlon. But then I thought it would be fun with some speed and signed up for the Olympic Distance in Cologne. Those last two are in the end of August. Then in October I want to do a Half Marathon, in Eindhoven or Amsterdam.

Coach Hanneke: Sounds good. Also like the bike. Looks like my size... All right, concerning future training: you just had some rest after Kilsbergen. Midsummer weekend and so forth. Go back to Build periods, keep the intensity up. Weren't you going to the Alps for some mountainbiking? That will bring you some endurance rides, though you don't really need it. But heck, sometimes life gets in the way of your schedule. At least try to include some good climbing sessions, get your heart rate up. Also keep up the interval work on the road bike. A maximum of 50 min of interval work should do more than enough, since you are training for Olympic distances or less. As for running, skip the longer runs because I fear they are helping you get injured. You have done enough long runs in the winter and spring anyway. I would say a maximum long run of 60 minutes with some tempo intervals for 20-30 minutes in total. Second run for a week is a normal interval run, like 10x1K or 5x2K or whatever. Include some hill work, you'll need that for the off-road triathlons. Keep up the good work with your core training (I see you have been a bit sloppy those last weeks...).

Athlete Hanneke: Yes boss.

Coach Hanneke: And for goodness sake, go swimming. You are a lazy swimmer.

Athlete Hanneke: Are you that harsh on all your athletes?? And I don't like the pool...I actually think I am developing an allergy to chlorine...

Coach Hanneke: (*Sigh*) Then swim in open water...

Athlete Hanneke: I am going to the Netherlands in July. Do you really suggest I swim in the Maas? When I was young the teachers at school told me that if I would accidentally fall in the Maas, I would need to go to the hospital to have my stomach emptied.

Coach Hanneke: Stop finding excuses, start swimming. Ask some friends where swimming is safe. There must be some clean rivers there... And it's more fun to train together anyway. Perhaps that will help you keep your motivation. It feels counterintuitive, but you wouldn't be the only one that feels it is hard to keep up training spirits during summer. There are so many distractions.

Athlete Hanneke: Guess I should find some other triathletes in the Netherlands then. Thanks for your understanding on the motivation part...

Coach Hanneke: Well yes, I know how it feels to do these trainings...

Athlete Hanneke: So are you happy with my race season so far?

Coach Hanneke: Definitely. It's rewarding to see you improve. You remember we agreed in the beginning of the season you would try to push yourself a bit harder, especially on the run? It seems to pay off. It's a fine balance between training and rest, but (most of the time) you are walking on the right side of the line. Though we'll have to keep a close eye on your running injuries...Keep me updated.

Athlete Hanneke: Thanks coach! Talk soon :).

The importance of an unimportant race

I think the concept of A-, B- and C-races needs redefining.

For those not familiar with the traditional concept: A-races are the meaning of your life, all you train for. B-races are as important as ice-cream after a training - nice, but you can do without. With C-races it's okay to stay in bed when it rains. Which, for most of you in Western Europe, has been a returning excuse those last few weeks.

Why? Last Saturday, I had a blast at a race the size of peanut and as important as the news in a glossy magazine. Despite 2 hours of mountainbiking in the morning, I decided to run a local 5K race in the evening. A hilly course (yes, there are hills in the Netherlands!) , which would be a good training for Kilsbergen Triathlon, but most of all, I'd promised to be there to catch up with an old friend.

In the queue to the registration, someone hands me a voucher worth one race entry. I don't know why and I don't ask. I feel lucky already. I am overjoyed to reconnect with my friend, whom I met on an amazing, stunningly beautiful trek in Nepal. We share many great experiences, from food poisoning to a helicopter rescue (I can recommend being careful with both, their safety standards really are different from ours).

European standards really are different from those in Nepal. Photo courtesy M. Merkelbach

Anyway, she will run 15K, my start is 20 minutes later. The route is partly off-road, winds through the sleepy village and then back up a short but steep hill. Locals are cheering along the way, runners greet their neighbours and in general, everyone seems to know everyone else. It's fun and I feel strong, but I avoid Big Pains. The final hill is tough, I keep telling myself that this is still flat compared to ... well, any country other than the Netherlands.  After 4.5K, I see my biggest fan Eric who tells me I am 2nd woman and 15th overall.  After 20m37s I cross the finish line with a big smile.

One of the biggest trophies I ever won :).

We can't decide whether we want pancakes, apple pie or some of the alcoholfree beer they sell, so we go for coffee.

I often catch myself thinking that all races are an A-race - and that only 'big' and 'tough' races count as A-races. I am disappointed if (when) I don't perform as expected. Even though my body should theoretically be able to run faster, my mind doesn't follow. Instead I think of work, the book I am reading - a thriller about a boy who gets lost in a forest, as a result I am now afraid of running in the dark- and of the apple pie at the finish line. As if others wouldn't take me serious if I admit I actually like those small, unimportant races. As if I feel I am not a real triathlete when I admit I like the speed and intensity of the Olympic Distance. Not to mention the fact that you don't have to wait 11 hours before you get to shower. While others sign up for Ironmans and ultra-marathons and enduro marathons, I run a 5K. And how I love it!

Not all races are A-races. Perhaps I should have only A-races and U-races - unimportant races. Or A-races and LOL-races. Goal: to have fun while training. Cramps in my stomach, but from laughing too much. It doesn't mean those races aren't hard. But just like your brain can't handle all the information in a Chinese whisper, it can't handle more than 3 A-races per year. It won't allow you to push your body as far as you do in an A-race. There is a good reason for that - mental burnouts, overtraining and your partner leaving you because of overobsession with your sport. So enjoy all those B- and C-races (or U- and LOL-races), have a beer and apple pie afterwards. Laugh with friends and stay in bed when it rains.

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.

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...

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.

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