Dietary Periodization – Strategic Carbs

Do Strategic Carbs work?

This study took a look at the strategic carbs strategy (Louise Burke. Fat adaptation and glycogen restoration for prolonged cycling—recent studies from the Australian Institute of Sport. Australian Journal of Nutrition and Dietetics, vol. 58, no. 2, 2001, p. S23+). The study looked at:

… a period of exposure to high fat, low CHO intake, followed by the restoration of muscle glycogen stores with a high CHO diet.

Such ‘dietary periodisation’ aims to enhance the capacity of both glycolytic and lipolytic systems to oxidative metabolism during prolonged exercise, by increasing the contribution from fat to substrate metabolism while potentially sparing intact muscle glycogen stores

Here are the results:

The fat adaptation diet caused major changes in fuel utilisation during sub-maximal exercise, with at least some of the adaptations persisting on day seven, even in the face of a plentiful CHO supply. As dramatic as these metabolic changes were, they failed to improve the performance of the cyclists’ time trial.

Together with other research, this study fails to find evidence that fat adaptation strategies offer any benefits for the endurance athlete.

The only remaining question is whether there are any advantages for ultra-endurance athletes who compete in events undertaken at a lower intensity and for longer periods (e.g. four hours or more). For these athletes, fat is the predominant fuel source.

 

Train Low, Compete High

One popular Low Carb strategy is to train low and compete high. The basic strategy is to do all training in a fat adapted state and then switch to a higher carb state a day or two before competition.  A study took a look at this methodology (Havemann L, West SJ, Goedecke JH, Macdonald IA, St Clair Gibson A, Noakes TD, Lambert EV. Fat adaptation followed by carbohydrate loading compromises high-intensity sprint performance. J Appl Physiol 2006 Jan;100(1):194-202.). The study consisted of six days of High Fat diet to a High Carb diet on the 7th day. The study looked at the performance on the 8th day. The purpose of the carb fueling was to fill glycogen stores before the final tests.

The ingestion of a HFD for 6 days resulted in a shift in substrate metabolism toward a greater reliance on fat and a reduction in CHO oxidation. The increase in fat oxidation in the present study persisted despite 1 day of CHO loading on day 7 as demonstrated by the lower resting RER (0.77  0.02 vs. 0.88  0.05, Fig. 2) and higher circulating FFA (Table 7) during exercise after HFD-CHO compared with HCD-CHO on day 8.

Here’s what was valuable about this 2006 study.

The study is unique in that it is the first study to investigate the effect of high-fat feeding, followed by CHO loading, on endurance exercise, including high-intensity sprints that simulate actual race situations.

In spite of being on a High Carb diet the effects of the High Fat diet persisted. This could be seen in a lower RER value indicating increased fat oxidation. However, the sprint performance was not as good. From the discussion:

It was hypothesized that the potential glycogen-sparing effect of this dietary strategy (3) would be most beneficial for exercise that included high-intensity sprint bouts, where muscle glycogen is the predominant fuel. However, in contrast to our hypothesis, the HFD-CHO strategy actually compromised high-intensity 1-km sprint performance.

 

Effect of weight loss by ketogenic diet on body composition

An interesting study which is said to show good results for the keto diet and athletic performance (Hyun-seung Rhyu1 and Su-Youn Cho. The effect of weight loss by ketogenic diet on the body composition, performance-related physical fitness factors and cytokines of Taekwondo athletes . J Exerc Rehabil. 2014 Oct; 10(5): 326–331.).

The participants were randomly assigned to 2 groups, 10 participants to each group: the ketogenic diet (KD) group, and the non-ketogenic diet (NKD) group.

The diet/training period was only 3 weeks. The performances were compared:

Aerobic capacity was evaluated by measuring the time taken to finish a 2,000 m sprint. Whereas anaerobic capacity was evaluated by the Wingate test (), by measuring peak power, mean power and fatigue index using a Monark cycle ergometer (Monark 894-E, Sweden). Muscle strength was evaluated based on the measurement of: (1) grip force (TKK 5401, Takei, Japan) and back muscle strength (TKK 5402, Takei, Japan) using a digital measuring instrument, (2) muscle endurance by measuring the number of sit-ups performed in 60 sec, (3) instantaneous reactionary force by measuring time and distance on 100 m sprint and standing broad jump, respectively, and (4) balance by measuring duration on single leg standing with eyes closed.

The diet was only three weeks long. The body composition results were not great for Low Carb.

Changes in body composition

Variables KD (n= 10) NKD (n= 10) F-value


Pre Post Pre Post
Weight (kg) 64.11± 7.19 60.34± 6.59 63.69± 7.64 61.16 ± 7.84 G 0.004
T 89.927*
G×T 3.484
%Body fat (%) 12.59± 3.96 12.21± 3.59 11.31± 2.77 10.23 ± 2.63 G 1.283
T 4.486*
G×T 1.122
Lean body mass (kg) 54.65± 3.93 52.47± 4.67 54.94± 6.50 53.55 ± 8.16 G 0.067
T 10.457*
G×T 0.520
BMI (kg/m2) 21.44± 2.10 20.18± 1.79 21.08± 1.94 20.23 ± 1.97 G 0.032
T 86.936*
G×T 3.282

The KD kids lost twice as much weight which is good. The %Body fat wasn’t changed nearly as much in the KD group as in the NKD group. Worse than that, the KD group lost much more Lean Body Mass. BMI tracked the weight loss again demonstrating the weakness of the BMI measurement for tracking body composition. I think it may be the case that the LBM mass was mostly from lost water weight.

But how about performance?

  • KD did better on the 2,000 meter sprint after training than before. The NKD didn’t show much of an improvement. However, the timeframe listed in the results was 500 minutes. I don’t know how to make sense of that timeframe. It took the participants over 8 hours to sprint for a mile and a quarter?  Could the units be in seconds? If it was seconds then the time would be 8 minutes to run a little over a mile. That is possible in high school athletes.
  • What is striking is how much worse both of the groups did after training. Both groups lost peak power and mean power and the KD group lost significantly more power than the NKD group.
  • Another striking parameter was how much worse the NKD group got in anaerobic fatigue after the training. That is surprising.
  • The KD group did worse on grip strength gains.
  • The KD group did not improve as much on back muscle strength gains.
  • Both groups took longer on the 100m sprint.
  • Both groups could not jump as far in the broadjumps after training.
  • Equally disturbing was the lack of improvement in the sit-ups on the NKD group compared with the KD group.

All in all this points to a fatigued group for the final tests. It is possible to speculate that the KD group was less fatigued because the performed at a lower rate during the week or two of keto adaptation and stored up strength during that period. They show less signs of fatigue.

Issues with the study

  • One of the issues is that the performance tests were performed after fasting for 12-hours. That seems like a unlikely scenario which greatly benefits the Lower Carb cohort. In a more likely scenario both groups would have followed their diet.
  • There seems to have been no test such as RER or even measurements of urine ketones to verify ketosis in the Low Carb cohort.
  • The High School students were given lists of foods to eat. There were no food logs and no verification of compliance. There was no dietary analysis at all.
  • Muscle endurance was done by seeing how many situps could be done in 60 seconds.
  • There was no control group in diet.
  • The standard deviation bars on the data were much bigger than the change effects.

Taekwondo is characterized as:

a comprehensive physical exercise involving high intensity movement of the muscles and joints of the whole body at the mean 85–95% HR-max

Yet, I can’t find an explanation of the time duration of Taekwondo.

 

Another VO2max Test – Van Wilder

I’ve got another friend, call him Van Wilder, who got his VO2max tested. He’s a 35 year old triathlete who has done an Ironman and marathons. He has about five years of running training. He did the Ironman fat adapted with very few carbs during the event. He’s recently gotten off the Low Carb bandwagon, at least partly. He is still lower carb.

Van Wilder’s VO2max came in at a respectable 59.8. That puts him within 5% of the elite athletes like Zach Bitter and Ben Greenfield. Van Wilder’s max fat oxidation rate is very close to the top levels measured in FASTER  (Jeff S. Volek, Daniel J. Freidenreich, Catherine Saenz, Laura J. Kunces, Brent C. Creighton, Jenna M. Bartley, Patrick M. Davitt, Colleen X. Munoz, Jeffrey M. Anderson, Carl M. Maresh, Elaine C. Lee, Mark D. Schuenke, Giselle Aerni, William J. Kraemer, Stephen D. Phinney. Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism, Volume 65, Issue 3, March 2016, Pages 100-110.).

Here’s Van Wilder’s %VO2max vs Fat and Carbs Oxidation rates (in kcal/min).

At his peak he’s burning somewhere around 12 kCals a minute of fat. At the end Van Wilder is burning more than 22 kCals a minute of carbohydrates. His point where he’s burning 50% fat-50% carbs is at 80% of his VO2max. His peak fat oxidation is around 58% of VO2max. However, the point where he start burning carbs is relatively low at 45% of VO2max.

Compare his data with mine. I am fat adapted and only eat keto/low carb. I’m also 23 years older and not as trained by a long stretch.

Here’s the differences:

Parameter Van Wilder Doug LCS
Max Fat Oxid.
(kcal/min)
13 11
Max CHO Oxid.
(kcal/min)
22 22
%VO2max
Max Fat Oxid
58 53
%VO2max
Max CHO Oxid
100 100
%VO2max
50% Fat Oxid
50% CHO Oxid
80 78
%VO2max
Max Fat Oxid
Zero CHO Oxid
43 59

I would like to suggest that the main difference is found in the last row. My rate at which is expend no carbs and burn the most fat is at about 59% of my VO2max. Van Wilder’s point is about 43% of his VO2max.

Now my VO2max at 34.1 is significantly lower than Van Wilder’s at 59.8. And that probably explains a lot of the difference above. Van Wilder still looks to me like an efficient fat burner. Especially when compared to Damian Stoy.

Competition Fueling Strategies for Van Wilder?

What should the fueling strategy be for Van Wilder? Seems like he currently has the advantage of metabolic flexibility. He can certainly use fat for fuel at lower intensities.

 

NIKO NIKO Pace

There is another slow steady heart rate training called Niko Niko. Here’s a good page describing it (NIKO NIKO PACE – THE GENTLE PATH TO SUCCESS).

The formula for heart rate is different than the Maffetone MAF heart rate. Niki Niko uses:

138 minus half your age.

So for me at 58 that would be 138 – (58/2) = 109 bpm. That’s not too far below my MAF heart rate of 112-122. It it at an interesting point on myVO2max test results as well. A heart rate of 109 actually has a higher fat oxidation rate than the extrapolated curve (where the real world data veers from the idealized curve). It is certainly a good point for fat burning.

The MAF number has shifted my performance upwards in just the past three weeks. Here’s my splits from my MAF test three weeks ago compared with my MAF 5 mile this AM. I’ve had to go from walking to a little jogging and walking mixed together.

That’s a pretty good improvement – around a minute and a half.

Slower But Fitter?

An interesting study put a group of endurance athletes on a Ketogenic diet and measured their performance as well as body composition changes (Zinn C, Wood M, Williden M, Chatterton S, Maunder E. Ketogenic diet benefits body composition and well-being but not performance in a pilot case study of New Zealand endurance athletes. J Int Soc Sports Nutr. 2017 Jul 12;14:22.). The study concluded:

All athletes increased their ability to utilise fat as a fuel source, including at higher exercise intensities.

Mean body weight was reduced by 4 kg ± SD 3.1 (p = 0.046; effect size (ES):0.62), and sum of 8 skinfolds by 25.9 mm ± SD 6.9; ES: 1.27; p = 0.001).

But how was their performance?

Mean time to exhaustion dropped by ~2 min (±SD 0.7; p = 0.004; ES: 0.53). Other performance outcomes showed mean reductions, with some increases or unchanged results in two individuals (VO2 Max: -1.69 ml.kg.min ± SD 3.4 (p = 0.63); peak power: -18 W ± SD 16.4 (p = 0.07), and VT2: -6 W ± SD 44.5 (p = 0.77).

Was this an adaptation problem?

Athletes reported experiencing reduced energy levels initially, followed by a return of high levels thereafter, especially during exercise, but an inability to easily undertake high intense bouts. Each athlete reported experiencing enhanced well-being, included improved recovery, improvements in skin conditions and reduced inflammation.

In the end the athletes likes the health benefits even with the performance losses.

Bought a new toy

I just bought myself a Concept 2 Rower. I used one at Crossfit a couple of times.

I bought it with a Polar H7 Heart Rate strap.

This allows rowing with heart rate monitoring.

I will be using the same MAF heart rate number of 180 minus age (range of plus 0 minus 10). For me, at 58 years of age, that’s 112 – 122 bpm.

 

Carb Burn Minimum / Fat Loss Maximum

Is there a single point in exercise which represents that maximum fat oxidation and minimization of carb burning or are those two different points? If we take a closer look at Ben Greenfield’s VO2max test we can see that those are two different points.

The point marked as 1 in this chart was the point where Ben was burning a minimum amount of carbohydrates. The point marked as 2 was where Ben was burning a maximum amount of fat.

Where are these points? Ben’s VO2max was 61.1. Ben’s min carb number (1) was at a VO2 of 27.2 or 44.5% of his VO2max. Ben’s max fat number (2) was at a VO2 of 36.4 or 59.6% of his VO2max.

Note that the line 1 was 1.04 g/min of fat oxidation. That’s not too far from Ben’s maximum of 1.15 from line 2 (only about 10% difference in absolute rates. However, at point 2 Ben is burning a substantial amount of carbohydrates with 21% of his expended energy coming from carbs.

The MAF number is essentially line 1 although we don’t have a direct measurement of Ben’s heart rate at that point it is clear that is the point where he is relying the least on carbohydrates for energy and it within about 10% of the maximum possible fat burning rate anyway.

In my case, for whatever reason, my RER got well below 0.7. It may be my fat adaptation. I heard Ben state on a podcast that he was eating 100g of carbs a day and training for triathlons during the lead in to this FASTER study. That may explain why I got a lower number for RER at my minimum.

My min carb oxidation number was the point where my RER crossed over 0.7 which was at 63% of my VO2max. I don’t have the same absolute (grams per minute) column on my data that Ben had on his data so I don’t know if that was different than the max fat oxidation rate.

Surprisingly my rate is much higher in %VO2max. Equally, my %VO2max value was 34.2 and not 61.1. Ben is a young elite athlete. I am not. My VO2/kg at point 1 was 21.4. Ben’s was 20% higher at 27.2.

So bottom line is I have to work out at 65% of my VO2max to get the same effect Ben gets at 45% of his VO2max.

 

Fat Adapted Athletes

Here’s a great study on fat adapted athletes (Lambert EV, Speechly DP, Dennis SC, Noakes TD. Enhanced endurance in trained cyclists during moderate intensity exercise following 2 weeks adaptation to a high fat diet. Eur J Appl Physiol Occup Physiol. 1994;69(4):287-93.).

The study looked at five cyclists and compared them on a High Carb vs a High Fat diet.

Despite a lower muscle glycogen content at the onset of MIE [32 (SEM 7) vs 73 (SEM 6) mmol · kg −1 wet mass, HIGH-FAT vs HIGH-CHO, P < 0.01], exercise time to exhaustion during subsequent MIE was significantly longer after the HIGH-FAT diet [79.7 (SEM 7.6) vs 42.5 (SEM 6.8) min, HIGH-FAT vs HIGH-CHO, P<0.01]

Looks like they have an almost 2x advantage when it comes to endurance.

How long did it take to convert these athletes from Carb Adapted to Fat Adapted?

These results would suggest that 2 weeks of adaptation to a high-fat diet would result in an enhanced resistance to fatigue and a significant sparing of endogenous carbohydrate during low to moderate intensity exercise in a relatively glycogen-depleted state and unimpaired performance during high intensity exercise.

Only two weeks!