Carbohydrates are undisputedly ergogenic aids for endurance exercise training. There basically isn’t a single study out there that shows a negative effect of carbs on performance. So when going Low carb in training period, your training performance will suffer, either in volume, intensity or RPE (rating of perceived exertion). I finally managed to perform an analysis of my key training periods before Hawaii Ironman triathlon 2012 (High Carb) and before Hawaii 2013 (Low Carb), that confirmed my initial observations and findings from scientific literature.
I compared the last 14 weeks of training heading into Hawaii Ironman in 2012 or 2013 (three 4-week training blocks + 2-week taper), as this is considered the most important training period before Ironman race. In 2012 I was still on “traditional endurance” High Carb diet, in accordance with all guidelines and with no junk food. For 2013 season I changed to Low Carb nutrition at the start of the year, so the compared period in 2013 was well after adaptation to new nutrition (i.e. 8 months after the switch to Low Carb).
The first (and easiest) comparison is of course the volume of training, represented in km or hours.
The numbers speak for themselves, as 11% reduction in total training time was hard to overlook even back when I was training for 2013 Hawaii. I averaged 3 h 03 min per day in 2012 and only 2 h 42 min per day in 2013. Only swim volume was greater in 2013, and that was due to broken ribs and arm lacerations in 2012, that limited my ability to swim. Both run (-18%) and bike (-18%) volumes were markedly lower in 2013, in accordance with previous observations, that I just couldn’t train that much. It wasn’t for the lack of time or motivation; it was just the volume that was killing me in 2013.
As far as the sleep goes, I averaged 9,0 hours of sleep per day in 2012 and 8,6 hours in 2013, so no major differences.
WORKOUT TYPE COMPARISON
The volume is only one determinant of training, with quality being probably more important. So the comparison of workout types may provide a better glimpse into changes between my 2012 and 2013 Hawaii preparation period.
In running, I did a couple more interval training sessions and a couple of tempo and long distance workouts less in 2013 when compared with 2012. The major difference comes in other run workouts (i.e. recovery runs, “garbage miles”…), that I performed almost one third less in 2013! And the picture is almost identical for bike workouts in 2013, with the numbers of workout types quite similar except of “garbage miles” workouts (approx. one fourth less in 2013). So all in all, the quality of training was more or less comparable between 2012 and 2013, also confirming my initial feelings.
RPE, FATIGUE, WILLINGNESS TO TRAIN
As mentioned before, I also track Rating of perceived exertion, Fatigue and Willingness to train for every session. I assign a 0-9 value to each based on the following index:
|Rating of perceived exertion
||Willingness to train
|1 – Very light
3 – Fairly light
4 – Moderate
5 – Somewhat hard
6 – Hard
7 – Very hard
9 – Maximum
|1 – Feeling new
3 – Rested
5 – Average
7 – Tired
|1 – Very High
3 – High
5 – Average
7 – Low
9 – Zero
So another possible comparison between years could be based on RPE, Fatigue and Willingness to train criteria. RPE is excellent measure of how hard I went in each session (i.e. intensity) while Fatigue and Willingness to train are good indicators for overtraining status. By comparing these indicators for key workouts, I can get another view of the training quality.
I averaged these indicators for key workouts (i.e. interval, tempo or distance workouts) and for “garbage miles” workouts (i.e. all other).
When looking through results, no difference appears in “garbage miles” workouts, whether they were run or bike workouts. This would indicate that intensity was the same as well as Fatigue level and Willingness to train. But when looking at averages from key workouts (i.e. intervals, tempos and distance sessions), the most notable difference is RPE, being quite higher in 2013 for both run and bike workouts. While on first thought this would indicate higher intensity and quality of key workouts in 2013, I would most probably ascribe that to typical characteristic of Low Carb training. Namely, for a given workout performed at lower muscle glycogen content (which is the case in Low Carb training) the RPE is higher at the same intensity or power. This fact is well established and proven in scientific literature, as subject always report higher RPE on Low Carb for the same workout intensity in comparison to High Carb.
Also, the track run workouts indicate the above mentioned fact of higher RPE at same pace as well. In 2012 I was performing 10x400m run repeats at 74 sec with average HR 150 bpm and 60 sec rest periods in between, while in 2013 I could only do 77 sec 10x400m repeats with average HR 150 bpm. But on 90 sec rests, so the overall intensity was substantially lower in 2013, albeit at higher RPE!
MY 2013 NUTRITION
Unfortunately, I do not have any nutrition data for the last 14 weeks before 2012 Hawaii when I was training High Carb Low Fat, but I would guesstimate that I was consuming well over 500 g of carbs per day. Probably more in 600 – 700 g region, as only my usual (cereal) breakfasts consisted of more than 200 g of carbs!
I started tracking my nutrition intake in 2013, so I have complete nutrition data for whole year. In last 14 weeks of training for Hawaii in 2013, my average daily carb intake was 199 g on 5.011 kCal consumption.
Average fat intake was 360 g, while protein at 231 g, which means that I got almost 2/3 of my energy from fat! As far as food groups goes, they averaged out as follows.
Quite evidently, the most important training period (14 weeks before an Ironman) was lower in volume and at best similar with regards to quality in 2013 when compared to 2012. But as stated before, training performance is of minor importance with regards to race performance, as I train for races and not for training “bragging rights” 😉 The end result of different training approaches taken in 2012 and 2013 can be nicely summarized by the following graphic:
Comparison of 2012 and 2013 Ironman Hawaii race performances (2013 was Train low Race high Carb approach)
So where did this 38 minute (7%!) improvement come from? Some of it was evidently from better weather conditions, some were undoubtedly because of additional endurance training year, additional experiences… And I believe the major factor was also a change in nutrition. As far as I experienced until now, the Train Low Race High approach with regards to carbs has two major advantages:
- Smaller reliance on carbs for fuel and correspondingly greater fat burning capacity, which means lower chances of bonking.
- Greater training adaptation at lower (or the same) training stimulus (i.e. intensity and volume).
Especially the second advantage is most often overlooked and seldom mentioned. This may also be the consequence of quite limited research on this topic, as you can basically count studies that deal with this question on the fingers of one hand! But sadly, this advantage is in my opinion also one of major reasons, why people don’t stick with Low Carb training approach. They only see the reduction in performance in training, get scared and conclude that they are not suited to Low Carb.
In my opinion, based on my experiences gather so far and with regards to studied scientific literature, I could compare Train Low Race High Carb approach to altitude training. You are training at tougher conditions (higher altitude or lower muscle glycogen content) so that the races seem easier (sea level altitude or full muscle glycogen)!