Vo2max intervals: a love-hate relation

Some of you might know about these type of intervals. They are generally short effort performed at 105-130% of Functional Threshold Power (FTP) or 80-100% of Maximal Aerobic Power. There are plenty of duration possibilities but I usually go with 2 to 5 minutes intervals with equal rest time between efforts. Their general purpose is obvious: increase one's Vo2max, the maximal oxygen volume your body can process during exercise. I think they are essential in a training programme because they bring some adaptations required to raise the aerobic ceiling but they also provide some of the lower intensities adaptations as well. So, they are essential, but I hate em, and love em at the same time. Here's why.

Damn you, pain!

Yes, these are painful! They generally have a relatively high anaerobic contribution especially in the first effort when your anaerobic stores are fresh. Depending on intensity, duration and pacing strategy, you can manipulate the anaerobic contribution to these efforts and therefore make them more or less painful. Though they will remain very uncomfortable. The intensity means you will create a relatively important oxygen deficit in the first few minutes and depending on your particular physiology (Vo2 kinetics) you will reach the effort's oxygen requirements within a given time duration, usually between 60 and 180 seconds. Say you are very well trained and gifted, and reach the required O2 consumption within 60 seconds during a 4 minutes effort, this means you will theorically spend 3 minutes at your maximal O2 consumption, since the effort's intensity is supposed to ellicit Vo2max. Overall, it all means the same thing: pain in your legs, pain in your chest and soft arms.

They are hard to perform on a flat terrain at a certain intensity. Or at least I prefer doing them on climbs because the power is more consistant, more specific to my racing demand and aerodynamics play's less of a role. So they are perfect for hill repeats if you have some long enough hills nearby.

They generally dont create a large kilojoules expandure since the total work duration is usually between 15 and 25 minutes of effort. For those on a kJ's target, they might not be the best type of workout, even though this aspect is debateable.

Finally, I see them more as a complement, the icing on the aerobic cake (who once said that eh?) so you might not want to live on a steady diet of these intervals. Careful, it does not mean they should only be included in your programme when racing comes close, as is the general belief in the power training community. They do induce a significant fatigue so they should be planned carefully in your programme along with well thought out rest days. Indeed, these efforts rely heavily on your glycogen stores so they should generally be attempted in a well rested state unless you are doing some sort of block including multiple days of hard efforts

Yay, only one more to go!

Given the low total work duration, the workout is usually pretty short and all intervals can be done within a 60 minutes workout. Sure the first, second, third intervals are very hard but the mental pain eases off when you reach the second to last interval. I always see the last effort as a bonus. Easy done, only 4-5 minutes of pain and it's over! Ironically, my last effort is often my best one.

The logistic of such a workout is pretty easy to sort out: find a 4-5 minutes hill, climb it 4-5 times and use the descent as your rest time. The best type of hill is a steady one so you can settle in a certain rythm. Speaking of which...

I like these efforts because their duration allows you to settle into a steady, yet very high rythm and maintain it for a nice chunk of time. This is especially true when doing 4 or 5 minutes efforts. Oh, did I mentionned 5 minutes intervals are WAY harder then 4 minutes ones? That additionnal minute makes a significant difference. The feeling of these intervals is pretty close to race situations when you are digging deep on some medium duration efforts. In my opinion, they are very cross-country specific since XCO racing almost always involves a medium duration hill on the course which is repeated 4-6 times.

Finally, I feel they are very effective at inducing marked aerobic changes that will impact a lot of other durations like your FTP. People generally dont think of them when speaking of mitochondria adaptations but the High Intensity Training guru's seem think otherwise (see my post on Hill Climb Repeats). I think they are a wise training strategy when coupled with either long slow rides or more sustained tempo work.

What if...?

Purely speculating about these intervals, I thought (and did read somewhere) they could bring significant skeletal muscle adaptations, namely mitochondria and capilary ones. I recall some high intensity training experts discussion on twitter relating the muscle recruitment patern of such high intensity efforts and targeted muscle fibers adaptations. The ''theory'' mainly speculated that these efforts recruited more motor units, therefore more muscle fibers, which would mean more fibers are working to produce power. More working fibers means more tissu needs to recover and adapt to the stress they ecountered during training. More targeted tissu for adaptations means more mitochondria density and size in more fibers. It also means more capillary density and more capillary arround more fibers too. Now this might be all broscience and pure speculation but the theory makes sense in some way.

What about doing these on hills? Hills generally mean lower cadence and more force applied. More force means more motor unit recruitment... Food for thoughts

Endurance Athletes and Carbohydrates Part 2

In Part 1 of my serie of blog posts on carbohydrates (CHO) and endurance athletes, we had an overview on the importance of post-workout carbohydrate feeding in the recovery process. It's main role is to refuel muscle glycogen stores in order to set you up for your next training session. This is one part of the recovery equation and CHO plays another major role in the recovery phase by starting its action during the training session.

Ingesting carbohydrates during training has been shown to possibly blunt the glucoregulatory hormonal response (insulin, glucagon, epinephrine, growth hormone and cortisol) during exercise. These hormones (except insulin) are responsible for the increase in blood glucose concentration. Their activity generally increases with exercise intensity or duration in order to level off blood glucose concentration since exercise intensity/duration depends on glucose as fuel. How does CHO feeding during exercise act on your body? What mecanism comes into play? Here is a brief summary of what happens.

Implications in recovery and peripheal fatigue

CHO feeding during exercise could lower blood concentration of the hormone cortisol. Altering cortisol secretions can have some positive effects on recovery. Cortisol is known to suppress the immune system by decreasing T-cells and therefore makes you more prone to catching infections and illness. To regulate blood glucose, cortisol uses the body's amino acids and transforms them into glucose and liver glycogen (neoglucogenesis). This means it can feed your body using it's own tissus such as muscle fibers and connective tissus. Decreasing neoglucogenesis by ingesting CHO during exercise could therefore accelerate the recovery process. During exercise, cortisol blocks glucose entry into the cells which could decrease exercise intensity by promoting free fatty acids (FFA) use as fuel. Less plasma glucose available for working muscles potentially leads to accelerated fatigue of those tissus and can compromise subsequent medium to long term recovery. Decreasing growth hormone effect has similar results since GH supports cortisol action.

Plasma concentration of hormone epinephrine is a strong marker of glycogenolysis. The more epinephrine concentration is found in blood, the more muscle glycogen will be used during exercise to maintain intensity level and liver glycogen to maintain blood glucose levels. Using liver glycogen to maintain blood glucose levels at a stable concentration means less glycogen is used for exercise specific oxidation. CHO feeding during exercise as been shown to reduce epinephrine production and could therefore spare muscle and liver glycogen use. Even though it might be a marginal change, sparing muscle glycogen knowing you only have about 400g available is always something good. The role of endogenous CHO feeding in that case comes down to regulate blood glucose concentrations in order to prevent using  liver glycogen stores to do that task. More glycogen is then available for specific muscle contraction during exercise and could delay exercise specific muscle fatigue.

Insulin levels during exercise generally follows a downward tendancy with exercise intensity/duration. Ingesting CHO during exercise could help maintain insulin secretions at resting levels and could even slightly increase it's production. The main action of insulin is to uptake blood glucose and store it as muscle and liver glycogen. Having normal or slightly elevated insulin levels could then accelerate the recovery process by increasing the rate of blood glucose uptake to cells. It could contribute to muscle and liver glycogen synthesis during exercise as well, delaying peripheal fatigue.

To summarize, endogenous CHO ingestion during exercise helps maintain blood glucose levels stable and blunts glucoregulatory hormones response. Lowering the effect of these hormones could have implications in exercise intensity, fatigue during exercise and post-workout recovery mainly by sparing muscle glycogen stores.

Some theories involving CHO feeding during exercise and glucoregulatory hormonal response are linked to the onset of central fatigue. Decreasing the glucoregulatory hormones effect by CHO feeding leads to more stable blood glucose levels and thus, less free fatty acids blood concentration and oxidation during exercise. FFA blood concentration is thought to promote fatigue during exercise, which brings us to Part 3 in a few days.

Maximal Aerobic Power Test: so short yet so painful!

First full week of work in months! It was a draining week at my new job and it requires some adaptation. Sleeping patern has changed and I am now usually in bed by 20h30-21h00! That is pretty crazy. I had some sluggish sensations during training this week and felt my legs lacked the high intensity feel. I finished working at 14h00 today (friday) and I was planning on doing my MAP test to see where I was at with my fitness. I fueled accordingly yesterday and today and was NOT looking foward to the pain! Those tests make me nervous just like the stress you feel on the start line when racing.

I have been using MAP tests for a while now and have a serie of datas I can refer back to in order to gauge my fitness and progression. I use the British protocol of 25 watts increments per 1 minute. Canadian riders are more familiar with the canadian protocol which consist in a 30 watts increment every 3 minutes. MAP tests are very protocol dependant. I like MAP tests better then the popular 20 minutes test because it is shorter and is not pacing dependant. The most important factor is picking a protocol and sticking to it in order to compare results from one test to an other. I use this protocol for 3 reasons: 1) it is used by highly reputable British and Australian coaches and sport facilities, 2) it's a protocol from which you can estimate your Functionnal Threshold Power (FTP) and 3) it's easily done on an indoor trainer.

Estimating your FTP from a MAP test result

The result from your MAP test is the last minute average power, usually the highest 1 minute power during the test. From that data you can extrapolate your FTP. It has been said that one's FTP usually falls within 70% to 80% of MAP. Most people use 75% but I prefer being conservative so I use 72% of my final result. Depending on the individual, FTP could be lower then 70% or a little higher then 80%. Another interesting data you can obtain from this test is your mean maximal 5 minutes power. The test's intensity usually does a good job forcing you to produce a high 5 minutes power in the last stages of the test. Typically, a rider's best 5 minutes power should be arround 90% of his MAP using the protocol described above.

The results

Since you might be a power data geek, here's the part you are probably looking foward to: today's results. I am not too much into personnal number showing and all that stuff because I think it sounds pretentious but for the sake of the blog post I will include my personnal numbers. Last 2 tests were done at the end of december and during the first week of febuary. Oddly enough, both tests resulted in the exact same MAP and 5 minutes power: 463 watts and 410 watts respectively. The only difference being the december test saw me lasting 8 seconds in the 475 watts step whilst I lasted 22 seconds in that step during the febuary test. At the time I was a little annoyed by the test's results because I had no improvement. Reflecting on the situation with the precious help of my mentor I realized the result was not bad at all since I was in the middle of a pretty intense training block involving a lot of Vo2max type of efforts. Following this block I headed south 2 weeks ago and could log some long rides and I think all of this is starting to pay off.

                     

The multiple steps of a MAP test

Despite the fatigue and lack of confidence in my form I stepped into the pain and did my test today. The test went very well and I managed to complete the 475 watts stage and log a mere 1 second in the 500 watts step! Final results are looking good for the upcoming season: 483 watts MAP, 425 watts 5 minutes power and a 340-345 watts estimated FTP. All of which, at my body weight, are not numbers to be shy of. Estimated FTP would be exactly 347 watts but given the powermeter has an error margin I prefer staying conservative and call it 340-345 watts. The 5 minutes power is about 87%-88% of my MAP, which makes some sense since I am a bit of a diesel engine.

Its worth giving a try to such test, is easily perform on an indoor trainer and repeatable. I am quite pleased with today's results and it looks very good for the upcoming season. I hope I still have some room for improvement. But for now, I will concentrate on upcoming training sessions. Actually not looking foward to them with the new power target I will need to hit!



Endurance Athletes and Carbohydrates Part 1

A balance in macronutrients is essential in an endurance athlete's diet and we sometimes hear people trying out some funky nutrition shifts such as high fat diet, low carbs diet, etc. One thing is sure, endurance athletes need to have a high proportion of their daily macronutrients intake as carbohydrates (CHO) to perform optimaly. CHO has a lot of functions within the body and I am going to try and make this a series of two or three posts on CHO in relation to exercise, recovery and fatigue.

Carbohydrates and recovery

Heavy aerobic exercise rely mostly on muscle and liver glycogen for fuel. The precious glycogen is stored in limited quantity within the human body and any moderate to hard intensity aerobic effort will be fueled from these reserves. The importance of post-workout refueling is therefore crucial for short and long term improvements. But how does it happen? Why is it so important? Here are some answers on the topic.

Carbs play a major role in the recovery process. Depending on exercise intensity and duration, muscle glycogen stores could be partialy to fully depleted. The average 70kg male has about 400g of muscle glycogen to spare and 100g of liver glycogen. Despite being trainable, the total quantity of stored glycogen remains limited. These reserves generally allow for a sustained moderate-hard effort of 2 hours before being fully depleted.

Post-exercise CHO feeding will ensure the recovery process kicks in by refueling your muscles and liver glycogen stores. A proper post-exercise CHO intake will also help your body trigger all the biological processes to set up training induced adaptations. Fueling back your tanks allows to be ready for your next training sessions. Therefore, better recovery means higher quality/quantity training on a regular basis to achieve your performance goals.

Quite often we can read or hear about the post-workout 30 minutes recovery opportunity window and it's major impact on muscle glycogen synthesis. Though this aspect has been debated, it appears evidence tends to suggest the actual opportunity window is an important part of the post-workout recovery process. Insulin response is high following exercise when CHO is ingested. Tissues sensitivity to insulin and glucose transporters such as GLUT1 and GLUT4 is also higher in the few minutes following hard exercise which would increase their hability to absorb glucose. In that optic, a high glycemic index carbohydrate solution should be prefered when aiming for optimal recovery. Liquid CHO with sodium intake is also favorable to ensure gastric emptying is processed faster.

Traditionnaly, we've been told ingesting a combination of CHO and protein (3:1 to 4:1 ratio) would accelerate the rate of muscular glycogen synthesis. A few experts have studied this issue and it appears coingestion of CHO and protein would only be useful if the quantity of ingested CHO (or total energy) is too low. Drinking a 1,2g/kg/h of a CHO solution (van Loon et al. 2000) would seem like a good approach to post-exercise CHO feeding for optimal recovery.

So what should you learn fro that? The importance of ingesting a liquid CHO solution in the few minutes following hard exercise or competition will enhance the body's capacity to recover. Muscle glycogen synthesis is a slow process which takes some time. Under optimal recovery conditions, 5-7% per hour of total glycogen reserve will be restored. Complete glycogen replenishment can  easily take up to 24 hours to be completed and most of the time 24 hours is not enough. This is a major reason to emphasize post-workout nutritional strategy to achieve your performance goals.

SRM home calibration

SRMs have this little feature that make them such great units: the possibility to calibrate your powermeter at home. Dont get the terms wrong here, people often confuse calibration and setting zero offset. This post is about slope calibration and therefore it is all about your powermeter accuracy and consistancy.

To calibrate your PM, you need your cranks attached to your bike, your PowerController head unit, an indoor trainer, a known weight (very important) and a pen and piece of paper. You need to install your bike on your indoor trainer so it remains leveled and does'nt move, it makes the job easier. Though, you can also calibrate your SRM while holding your bike still like I did with my MTB because it wouldnt fit on my trainer.

You need a known mass of around 20kg. It needs to be accurately weighted otherwise the calibration could be useless. Gym weights and such often vary by a significant amount of weight even though they are marked as 10kg, 15kg, 20kg etc. Any post office or private shipping carrier will have an accurate scale to weight your mass. Mine is a 20kg iron kettlebell that weighted in at 20kg bang on at the local post office (thanks to my post man brother).

All you need to calibrate your unit.

The protocol is pretty simple and takes about 5 to 10 minutes. You start by whichever side you like. Let's say you pick the left side. Turn on the powermeter by pedaling foward to trip the reed switch on. Measure your zero offset by pressing mode+set while the crank arm is in horizontal position. When the zero offset is stable, note the value. Load the weight onto your pedal while your crank arm is in the same horizontal position and wait for the loaded zero offset to stabilize; note the value. Repeat the procedure 3 times on each side noting all values. Little tip: if your bike is on the trainer, put the weight onto the pedal and rotate the rear wheel backward to lift the weight and level off the crank. Make sure you hold the rear wheel tight or squeeze the brake to keep the crank perfectly still. If your bike is on the ground without trainer, place your weight on the pedal and roll your bike backward untill the crank is horizontal, then squeeze the brake hard to make sure nothing is moving.

Once you have your values, you can do the old school maths or simply plot the values in an excel document to have it calculate your new slope for you. (Contact me if you need the document).

You will need to plot:
- crank lenght in mm
- your known mass to the gramm
- the right side unloaded zero offset (average from 3 values)
- all right side loaded values
- the left side unloaded zero offset (average from 3 values)
- all left side loaded values
- your current/old slope

The excel doc does the maths!

The excel sheet will calculate your new slope and the % difference compared with your old slope. Last time I calibrated my road SRM, my slope was off by 1,3%. I changed the slope to the new one. Yesterday I had a 0,58% difference. I decided not to change the slope as the factory calibration could be responsible for such a difference and I assume SRM factory calibration is more accurate then the home procedure.

Having an accurate powermeter is essential and some brands allow you to calibrate it yourself. SRM just has this little edge that make them such awesome units.

Home sweet home!

Ah!

Back home after some very good days in the USA! Currently pretty toasted from the long drive, crappy food and lack of sleep. I will recharge my batteries in the coming days and will update the blog with some more ride info from the training week.

New job starting tomorrow too, might get busy, but stay tuned and share the blog. Also feel free to comment at any time.

Cheers

Hill climb repeats

Such a cold day yesterday here in GA. Very windy, grey and cold air made it a perfect day to hide between Kennesaw Mountain trees and go for some hill repeats. That climb is awesome. The gradient is steady which makes it perfect for steady uphill intervals. It is 2,3km long, 165m total elevation and takes anywhere between 7min to 8min30sec depending on your intensity and if you're going for the odd strava KOM.

I headed there doing a nice little 35min warm up including a low/moderate intensity climb, went back to the base of the climb and started my planned workout. On schedule was 5 x 8min at 105% of FTP with rest time being the time it took to descend the mountain, which is about 3min30sec. Very nice and challenging workout. Managed all intervals almost at 110% of FTP which is pretty good and tells me im in pretty good shape at the moment, unless all the food and booze made me pack an extra 5kg since we arrived here. Hills repeat is pretty MTB specific on a muscle contraction and recruitment perspective. It generally makes you work in quadrant II and forces you to maintain good steady power. The descend was so cold I couldnt ride much longer and had to head back home after my repeats. My time up the climb was about 7min35sec which is decent since I was on a MTB with tires at 25psi. The strava KOM is set at 6min35sec if I recall correctly, which would make it do-able on a road bike at full gas effort taking the right lines up the climb. But im not too much into strava.

This workout is the perfect counter exemple of my last post on The Benefits Of Long Rides. It lacked a bit of intensity to be called a proper high intensity workout but lets consider it that way for the sake of the post. Remember the long rides physiological effect on mitochondria density and size? It was produced via complexe molecular reactions that could be summurized that way: 

Repeated low energy muscle contractions > Icreased intramuscular calcium concentrations > activation of CaMK > activation of the Master-Switch > mitochondria biogenesis = mitochondria adaptations.

Now high intensity workouts also have an important impact on mitochondria adaptations. Though they are stimulated by a different mecanism in the body that involves different molecular components compared with the ''long ride'' chain reaction, they result in the same Master-Switch stimulation.

High intensity training, what, or where is it?

Typically high intensity training is define as being above the second ventilatory threshold, usually above 4mmol blood lactate concentration or when the body can't manage the lactate accumulation. For FTP users out there, I would say from 110% above is a safe bet. Training at high intensities is generally done using work and rest intervals of different durations in order to accumulate a total amount of training stress at a target intensity. There are plenty of possible combinations ranging from micro-intervals to longer work intervals alternated with equivalent or shorter rest intervals. Generally, work and rest intervals durations will be dependent on the quality you want to train. That could actually make the subject of an entire post and even a phd thesis...

How it happens?

As opposed to long distance riding, high intensity efforts involve high energy muscle contractions. These contractions require a lot of adenosine tri-phosphate (ATP) which is simply the high energy molecule derived from nutrients. ATP is the body's energy for all physiological process and high energy muscle contractions require a lot of ATP. This requirement partialy depletes ATP stores which leads to an increase in the concentration of adenosine mono-phosphate (ATP with 2 phosphates removed). Increased AMP activates an enzyme called activated protein kinase (AMPK). AMPK is the signalor for the Master-Switch PGC-1alpha that eventually stimulates mitochondria biogenesis.


So what now?

High intensity training has its place in a training program. Obviously such a type of training has to be monitored carefully with appropriate volume and recovery. It also has a lot of other benefits and one I would like to discuss in a furter blog post is the muscle fibers recruitment and its impact on subsequent adaptations when using such a high intensity training approach.