The Protein Bonk
“After competing in the Hawaii Ironman in 1980, I was intent on racing the Ultraman (3.1mi swim, 156mi Bike, 32mi Run). I was one of the first athletes to compete in an Ironman back then and there were no specific guildelines to follow so my training was largely trial and error. To get in shape for this race, I trained 3 times it’s distance every week – 15mi swim, 450mi bike and 150mi running each week. Plus, since I was on the SEAL team, I was required to do SEAL training 5-7 days/wk. I went from a strong 175lbs to a sickly 138lbs…..
One night I went to take a bath but I had trouble standing and walking, so I crawled to the tub and eventually passed out. My wife took me to the emergency room, where all kinds of troubles were revealed. When asked to lift my head for a spinal X-Ray, I couldn’t do it. My vertebrae in my neck and back were compressed causing a restrictive range of motion. The blood tests revealed that my liver and kidneys were on the verge of shutting down. My left rotator cuff was torn and my left quadriceps was torn. There was severe plantar fasciitis in both feet. My body was literally eating itself for energy.”
- Don Mann (Adventure racing legend) from the book ‘The Complete Guide to Adventure Racing”
If you’ve been involved in this endurance training game for some time now, chances are that you have, at one time or another, gone a little too far, on too little carbohydrate and experienced the sensations of the dreaded bonk - when you call down to the power-house in the legs and Scotty replies back “I’m givin’ her all she’s got Cap’n”. If you haven’t experienced it, no doubt you’ve seen the results via Julie Moss (pictured above), Paula Newby-Fraser or the dramatic crawl off between Wendy Ingraham and Sian Welch. Either way, it becomes readily apparent that when blood glucose becomes dangerously low, the body will shut you down – quickly! Considering that the brain can only function effectively on glucose, this is an important protective mechanism.
There is, however, a different, far more dangerous kind of bonk for the endurance athlete – the protein bonk. This ‘bonk’ doesn’t possess the same drama or protective mechanisms as the glucose bonk and therefore has more long reaching, dangerous effects as described by Don Mann, above. Fortunately, most of us do not possess the same resolve as a Navy SEAL. However, even the serious recreational athlete can do serious (athletic career ending) damage if the warning signs of a protein bonk are not observed.
A little background physiology: When you take in dietary protein it’s initial fate is to be broken down into an amino acid pool that lies in wait within the blood and muscle tissue (see below).
This pool of amino acids can basically undergo 2 basic fates:
Obviously, it cannot do both and these 2 objectives are somewhat antipolar. One is an anabolic (building up) process, the other is a catabolic (tearing down) process.
Additionally, if this amino acid pool becomes low (due to stress or inadequate dietary intake to meet energy needs) the body can break down muscle tissue into it’s amino acid constituents to supplement this pool. This is catabolism at its finest. It should be noted that this is hastened by stress hormones which are released in response to physiological OR psychological stress. Or put another way, it is very difficult to grow and improve if you are swimming in work related, sleep deprived cortisol.
However, even if you are the coaches pet and do all of the little things that hasten recovery (as outlined in my last blog on Serious Recovery for Serious Athletes) there will always be a gap between the time required for metabolic recovery (refilling glycogen stores) and structural recovery (repairing muscle). In fact, muscle recovery can take 3-5 times as long as substrate recovery. Or, put another way you cannot afford to rest long enough between sessions for the muscle to repair itself structurally 100% after a hard session. After 2-3 days, you will have the energy to ‘go again’ even though the muscle is not 100% repaired. And so, there is residual ‘structural fatigue’ that is carried across from session to session and week to week.
This residual fatigue places progressively greater demand on the amino acid pool and thus less amino acids will be available for energy within the plasma, as more is going to the muscle for re-building. However, with sufficient motivation, you can rally the troops for a period of time by calling in Mr Caffeine, Mr Work Stress, Mr Family Stress to join your tug of war team and give some additional strength to the “break down amino acids for energy side”. However, this is a short term (ultimately destructive) solution. Eventually, the body calls on a weak but eventually effective protective mechanism to shut you down.
It’s actually a pretty neat protective mechanism. As it turns out, the same blood-brain transporter that carries essential amino acids also carries an amino acid by the name of Tryptophan. The same Tryptophan that makes you sleepy after a Turkey dinner. So, less transporters being devoted to Essential Aminos and more devoted to Tryptophan = Alan sleep now.
Put more succinctly, when available amino acids start to run low, you get sleepy – The Protein Bonk.
The extent of this lethargy can range from mild, for the astute athlete who recognizes the warning signs and incorporates a recovery period, to chronic in the case of the athlete who pulls out all the stops to ‘keep it rolling’ in spite of being tired. In fact, while Chronic Fatigue Syndrome is still largely a mystery, the 2 most pervasive markers are an increase in plasma Tryptophan concentrations and a decrease in plasma Glutamine (one of the essential Amino Acids) concentration. While scientists have discovered this correlation, some have been surprised to see that glutamine supplementation, while bringing the amino acid pool back to normal does not immediately abate the symptoms. Duh! While a relatively ‘deep’ amino acid pool is needed for muscle recovery, if you allow your body to drop 30lbs of lean tissue, like Don Mann, it will take a long time before there is enough amino acid surplus to bring plasma tryptophan levels back to normal. Or, in other words, you’re going to be tired for a long time. Even dropping one or 2lbs of LMM can create sufficient disruption to alter energy levels for a long period of time. For this reason, monitoring bodyweight over the long term is an important preventative overtraining strategy.
So, what can the intelligent athlete do to ward off the protein bonk?
1. Recognize that even with appropriate energy replacement, residual fatigue will be carried across from session to session and week to week. Therefore long term mesocycles and macrocycles that incorporate longer recovery periods are necessary.
2. Monitor bodyweight (and anthropometry) and learn the difference between short term fluctuations (day to day) related to glycogen depletion and hydration and long term changes (week to week) that indicate structural changes.
3. Be proactive in utilizing recovery strategies to assist the muscle repair process (see Serious Recovery for Serious Athletes)
4. Eat more protein. Elite ultra-endurance athletes experience a lot of muscular damage, both energetic and impact-related, therefore, high protein intakes are necessary, somewhere in the vicinity of 1.6-2.0 g/kg of bodyweight.
5. Pay attention to your body. If you are already tired (via training or work, travel etc) don’t reach for the caffeine and dig a deeper hole. Stop. Revive. Survive.