Category Archives: endurance

New study: very low carb diets don’t impair high intensity interval training (Cipryan et al., 2018)

Effects of a 4-week very low-carbohydrate diet on high-intensity interval training responses (Cipryan et al., 2018)

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Relevant study design details: 18 young, healthy, moderately-trained males. First, this was a study on exercise performance. Had it been on glucose management in patients with type 2 diabetes or obesity, this is not the population they would have selected. Second, they needed at least a moderately-trained population otherwise both groups would’ve made big n00b gainz which may have out-weighed any differences incurred by ketoadaptation in 4 weeks.

 

 

Third, 4 weeks is a good duration for this kind of study because maximal ketoadaptation occurs in about 3 weeks and doesn’t get stronger thereafter (gains seen beyond 3 weeks are more associated with training effects).

On to the dietary protocols, results, and 2 other relevant new studies… but for that, head on over to Patreon! Five bucks a month gets you full access and there are many other options. It’s ad-free and you can cancel if it sucks 🙂

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Endurance Performance Doesn’t Decline on a Low Carb Diet

The new study by Zinn and colleagues doesn’t debunk ketoadaptation. And the authors agree!

In brief, it was 5 ~50-year old recreational endurance athletes. They’ve been training a lot for a very long time. In other words, one way to view this study is the opposite of n00b gainz. Experienced exercisers don’t typically make gains in 10 weeks without drastically changing their training program or increasing protein intake – neither of which occurred in this study.

 

 

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20% off some delish stocks and broths from Kettle and Fire HERE. 

If you want the benefits of  ‘shrooms but don’t like eating them, Real Mushrooms makes great extracts. 10% off with coupon code LAGAKOS. I recommend Lion’s Mane for the brain and Reishi for everything else. 

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Long-term fat adaptation.

Ketoadaptation

More on physical performance and ketoadaptation

A timeline of ketoadaptation.

 

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Cyclical ketogenic diet and carb refeeds

Potential conclusion (pending full texts): “if you’re gonna keto, no need to carb”

I think these three abstracts are all referring to the same studies.  I haven’t seen the full texts.  My takes are in italics, after each abstract.

Exhibit A. The Effects of an Eight Week Ketogenic Diet vs. a Cyclical Ketogenic Diet on Performance and Testosterone in a Resistance Training Program (Lane, Lowery, Volek, D’Agostino, Wilson, et al., 2015)

Introduction: Our lab recently examined the effects of the ketogenic diet (KD) compared to a western diet regarding strength related performance; additionally, free and total testosterone was evaluated. Individuals on the KD saw similar adaptations in strength and similar changes testosterone. Comparisons of the KD against a cyclic (CKD) in strength, endurance, and testosterone have not been previously demonstrated in literature.

Purpose: Therefore the purpose of this study was to investigate the effects of the KD versus a CKD on performance and testosterone in resistance-trained males.

Methods: Sixteen resistance trained males participated in the study (age: 23.5 ± 3.3; weight: 187.6 ± 32.6). Participants on the KD consumed 5% carbohydrate, 25% protein, and 70% fat for 8 weeks. The CKD group applied the same macronutrient ratio to their diet Monday through Friday, while altering the ratio on weekends (50% carbohydrate, 25% protein, 25% fat). A periodized resistance training program was strictly followed 3 days per week throughout the duration of the study with high intensity interval training implemented on intermittent days 2 times per week by all participants. Participants were placed on a 500 kcal deficit derived from basal metabolic rate determined by the Mifflin St. Jeor equation. One repetition maximum (1RM) strength was assessed on deadlift, bench press, and leg press at baseline with a repeat assessment performed Week 8. Strength endurance was assessed on the leg press at baseline and re-assessed at Week 8. Free and total testosterone was evaluated at baseline and at Week 8. An ANOVA with repeated-measures was used to scrutinize the effects of KD and CKD on dependent variables assuming group (KD and CKD) and time (pre and post) as fixed factors. The significance level was set at p ? 0.05.

Results: There were no differences between groups in the performance tests or testosterone levels detected at baseline (p > 0.05). A time effect was observed for bench press and deadlift 1RM (p < 0.01). There was a trend towards a group by time interaction (p = 0.07) which favored an increase in the leg press 1RM in the KD group. There were no significant differences for leg press strength endurance in both groups. For free testosterone, there were no group or group × time interactions (p > 0.05). For total testosterone, there was a group × time interaction following the diet treatment (p < 0.02). The pairwise comparisons revealed that only the cyclic group decreased in total testosterone (10.3%, p < 0.02).

Conclusions: In regards to performance, a strict KD seems to augment positive strength related adaptations when compared to a CKD. These responses may be explained by sustained total testosterone levels seen in the KD group compared to reductions in total testosterone as a result of the fluctuations in macronutrient intake.

Practical Applications: Individuals attempting to optimize adaptations in strength performance while maintaining testosterone levels should perform a KD compared to a CKD.

My take: no difference between KD & CKD, despite testosterone declining in CKD.  This isn’t surprising because small fluctuations within the physiological range are not expected to affect these outcomes.

When protein and calories are controlled, and the #context is a 500 kcal deficit, not really sure what they were expecting.  Because of the constant deficit, insulin will be low even on the carb-up days, and those carbs are more likely to be burned off than replenish glycogen.

 

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Autophagy

Caloric restriction (CR) activates autophagy.  Intermittent fasting (IF) is basically kind-of-like the opposite of CR.  I’m not knocking IF.  The animal studies of autophagy, based on “chronic nutrition depletion,” more accurately reflect CR which results in decreased body weight or metabolic rate.   IF generally includes refeeds, resulting in weight maintenance.  Also, in the few human studies on it, weight loss (CR) but not fasting (IF) has been shown to induce autophagy.

If you’re actually losing weight over the long-term with an IF protocol, and thus are CR by definition, then I suspect you may be autophaging, too (yeah yeah, I know, that’s not really how autophagy works, but you get the picture).

Disclaimer: I’m relatively autophagy-agnostic; not really confident racing to maximize it is a great thing based on Human Studies.

Book: Autophagy in Health and Disease

 

autophagy-image

 

Exhibit A: autophagy in skeletal muscle

Tl;dr: “a little exercise is a better than a lot of fasting”

A1) Physical exercise increases autophagic signaling through ULK1 in human skeletal muscle (Moller et al., 2015)

The protocol: participants either fasted for 36 hours or received a glucose infusion before and during exercise (cycling at 50% max for an hour).

“In the present study, we demonstrate that short-term aerobic exercise activates autophagic signaling through ULK1 in human skeletal muscle, independently of nutrient background.”

They really should’ve stressed that the deck was stacked to show fasting activated autophagy… 36 hours of fasting is pretty long but it had no effect.

 

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Ketones, carbs, and physical performance.

Or more specifically, ketone monoesters and carbs.  Literally, this study was a high-dose ketone monoester supp sans caloric or carb restriction.  I know, weird right?

 

Ketone ester

 

Non sequiter nutrition notes, #context, etc.:

1) ketone esters =/= ketone salts.  Ketone salts are either sodium or potassium-dominant.  Ketone esters are essentially salt-free.  Possibly helpful background reading here.

2) nutritional ketosis =/= starvation ketosis =/= ketone supp ketosis.  Because #context.

Starvation ketosis, but not nutritional ketosis, is muscle-sparing.  Ketone supps sans carb restriction might be.

3) the theory of ketone supps for sport is: 1) ketones are an energetically favorable fuel; and 2) they’ll spare glycogen, theoretically allowing prolonged duration of moderate-to-high intensity performance.  Adding in carbs will likely further this.

4) I have no studies to support this, but the idea of ketone supps in the #context of high carb doesn’t sit will with me.  Seems like high levels of both substrates = mitochondrial overload and oxidative stress.  Maybe.

5) there’s a gradient of fuel use during exercise:

-explosive power: creatine, anaerobic

-high intensity: glycogen, anaerobic

-low intensity: fatty acid oxidation, aerobic

But it’s a gradient with a lot of overlap, and ketoadaptation further blurs the lines.

 

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Long-term fat adaptation

Recent comments about FASTER have upgraded this study to “the only long-term study on fat-adaptation.”  Needless to say, I disagree.  Again.

Side note: FASTER had no randomization or intervention (ie, confounded by selection bias, among others); they basically recruited long-term low carb & high carb ultra-endurance runners and measured the stuffings out of ’em.

Ultimately, they showed a very high maximal fat oxidation rate in low carb ultra-runners, 1.5 grams per minute.  This is important because MAXIMAL HUMAN FAT BURNING CAPACITY

 

TROGDOR the BURNiNATOR

 

In previous studies on SAD (Standard Athletic Diet haha), maximal fat oxidation at similar VO2max% has been reported to be much lower, <1 g/min (eg, Hetlid et al., 2015 and Volek et al., 2016).

 

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Cyclical ketosis, glycogen depletion, and nutrient partitioning

Meal & exercise timing in the contexts of “damage control” and nutrient partitioning are frequent topics on this blog.  I generally opt for a pre-workout meal, but nutrient timing hasn’t panned out very well in the literature.  That’s probably why I’m open to the idea of resistance exercise in the fasted state.  A lot of pseudoscientific arguments can be made for both fed and fasted exercise, and since a few blog posts have already been dedicated to the former, this one will focus on the latter.

The pseudoscience explanation is something like this: since fatty acids are elevated when fasting, exercise in this condition will burn more fat; and chronically doing so will increase mitochondria #.  The lack of dietary carbs might enhance exercise-induced glycogen depletion, which itself would bias more post-workout calories toward glycogen synthesis / supercompensation.  Much of this is actually true, but has really only been validated for endurance training (eg, Stannard 2010, Van Proeyen 2011, & Trabelsi 2012; but not here Paoli 2011)… and the few times it’s been studied in the context of resistance exercise, no effect (eg, Moore 2007 & Trabelsi 2013).  However, there are some pretty interesting tidbits (beyond the pseudoscience) which suggest how/why it might work, in the right context.

Exercising fasted or fed for fat loss?  Influence of food intake on RER and EPOC after a bout of endurance training (Paoli et al., 2011)

John Kiefer, an advocate of resistance exercise in the fasted state, mentioned: “the sympathetic nervous system responds quicker to fasted-exercise. You release adrenaline faster. Your body is more sensitive particularly to the fat burning properties of adrenaline and you get bigger rushes of adrenaline.”

Much of this is spot on.  That is, ketogenic dieting and glycogen depletion increase exercise-induced sympathetic activation and fat oxidation (eg, Jansson 1982, Langfort 1996, & Weltan 1998).

The question is: can this improve nutrient partitioning and physical performance?  Magic 8-Ball says: “Signs point to yes.”  I concur.

Contrary to popular beliefs, glycogen depletion per se doesn’t harm many aspects of physical performance.  A lot of fuel systems are at play; you don’t need a full tank of glycogen.

Effect of low-carbohydrate-ketogenic diet on metabolic and hormonal responses to graded exercise in men (Langfort et al., 1996)

High-intensity exercise performance is not impaired by low intramuscular glycogen (Symons & Jacobs, 1989)

Increased fat oxidation compensates for reduced glycogen at lower exercise intensities (eg, Zderic 2004), and ketoadaptation may do the same at higher intensities.

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More on physical performance and ketoadaptation

The various studies on how low carbohydrate diets impact physical performance are very nuanced.  Here’s what I mean by that.

Exhibit A. Phinney 1980

Phinney 1980

In this [pioneering] study, obese patients were subjected to a variety of performance assessments in a baseline period, then after 1 and 6 weeks of weight loss via protein-sparing modified fast (1.2 g/kg ideal body weight from lean meat, fish, or fowl; probably around 80 grams of protein/d, 500-750 kcal/d). They lost a lot of weight, 23 pounds on average, two-thirds of which was body fat. There was no exercise intervention, just the performance assessments.

During the ‘exercise to exhaustion’ treadmill exercise, RQ steadily declined from baseline to week 1 to week 6, indicating progressively more reliance on fat oxidation.  This was confirmed via muscle glycogen levels pre- and post-exercise: during the baseline testing, they declined by 15%; after 6 weeks of ketoadaptation, however, they only declined by 2%, while ‘time to exhaustion’ increased by 55%.  After only 1 week of the diet, time to exhaustion plummeted, as expected, by 20%.

This was, as mentioned above, a pioneering study in the field of ketoadaptation. It also challenges one of the prevailing theories of ‘fatigue’ 
while carb-adapted, the subjects fatigued after 168 minutes, with muscle glycogen levels of 1.29 (reduced by 15%); while ketoadapted, they fatigued after 249 minutes with muscle glycogen levels of 1.02 (reduced by 2%).  In other words, they had less glycogen to begin with, used less glycogen during exercise, and performed significantly better (running on fat & ketones).

Exhibit B. Vogt 2003

Highly trained endurance athletes followed a high fat (53% fat, 32% carbs) or high carb (17% fat, 68% carbs) diet for 5 weeks in a randomized crossover study. In contrast to Phinney’s study, these participants were: 1) highly trained; and 2) exercised throughout the study.

Maximal power output and VO2max during a similar ‘time to exhaustion’ test was similar after both diet periods.  Same for total work output during a 20 minute ‘all-out’ cycling time trial and half-marathon running time.  Muscle glycogen was modestly, albeit statistically non-significantly lower after ketoadaption; however, ketoadapted athletes relied on a higher proportion of fat oxidation to fuel performance as indicated by lower RQ at every level of exercise intensity:

Vogt RQ

Again, this is the essence of ketoadaptation. Physical performance as good as or better using fat and fat-derived fuels.

One reason Phinney’s glycogen-depeleted ketoadapted subjects may have done so well is their reliance on ketones (probable) and intramyocellular lipids (IMCL) (possible).  In Vogt’s study, IMCL increased from 0.69 to 1.54% after ketoadaptation…

Also, food intake and body fat declined, and training volume increased in the low fat group; whereas food intake increased, and body fat and training volume declined in the high fat group.  Reminiscent of anything?

High fat, low carb -> eat more, exercise less, STILL LOSE BODY FAT.

Vogt data

Sorcery?  No.  Diet impacts more than just mood and body composition – resting energy expenditure increased in the ketogenic dieters.  This isn’t an isolated finding.

Exhibit C. Fleming 2003 

This was another study in non-trained athletes, consuming high fat (61% fat) or control (25% fat) diets for 6 weeks.  The tests were the 30-second Wingate, to examine supramaximal performance, and a 45-minute timed ride, to examine submaximal performance.

This study differed from the previous two in several significant ways.  For starters, peak power output declined in both groups, slightly more so in the high fat group (-10% vs. -8%).  Furthermore, RQ didn’t wasn’t significantly lower during this test in the high fat group, which possibly suggests they weren’t properly ketoadapted.  In Phinney’s study, the large energy deficit ensured ketoadaptation; this study lacked that aspect, somewhat more similar to Vogt’s, although unlike Vogt’s, these participants weren’t athletes which presumably makes ketoadaptation more difficult.

There are many factors at play… I wasn’t kidding when I said these studies are very nuanced!

Exhibit D. the infamous, Paoli 2012 

These were ‘elite artistic gymnasts,’ who could likely beat you in a race running backwards.  The ketogenic phase consisted of 55% fat and much more protein than the control phase (39% fat; protein: 41% vs. 15%). The significantly higher protein content was modestly offset by slightly more calories in the control phase, which reduces the amount of protein required to maintain nitrogen balance.

In this study, performance was, for the most part, ‘maintained,’ with relative increases in a few of the tests; eg, the “legs closed barrier.”  Changes in body composition were more robust: significantly reduced body fat and increased lean body mass after 30 days of ketogenic dieting (with their normal exercise routine).

Paoli data

The major confounder in this study was the use of an herbal cocktail only in the ketogenic diet group; despite this, the results are largely in line with the other studies.  For more on this study, see here.

Exhibit E. the most dramatic one to date: Sawyer 2013 

Please see here for the details, but in brief, strength-trained athletes showed improvements in high intensity exercise performance after only 7 days of carbohydrate restriction.  The nuances of this particular study are discussed more here.

barbell

Collectively, these studies show that physical performance in both endurance and high intensity realms does not always suffer, can be maintained, and in some cases is improved by ketogenic dieting.  Important factors are duration (to ensure adequate ketoadaptation), energy balance, and regular physical activity (athletes and regular exercisers can adapt to burning fat much quicker than sedentary folks).

 

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New study: high intensity exercise on a low carb diet.

Switch an athlete from their standard carbohydrate-rich diet to a low carb ketogenic one and suddenly performance tanks.  It is known.  Give them a few weeks to adapt, however, and it recovers.  This much was established for mainly endurance-related performance parameters by Steve Phinney and colleagues in the 1980’s (eg, Phinney et al., 1983).  Then, along came Antonio Paoli, Dominic D’Agostino, and others who showed a similar phenomenon in gymnasts, a population that routinely exercises at higher levels of intensity (Paoli et al., 2012).  Notably, in these studies the athletes were allowed adequate time to adapt to the new metabolic milieu – sometimes referred to as ketoadaptation.  Three weeks appears to be the minimum amount of time required for ketoadaptation; ie, studies of shorter duration generally show: low carb = poor physical performance.


which is why I was surprised to see this one:

Effects of a short-term carbohydrate-restricted diet on strength and power performance (Sawyer et al., 2014)

These researchers subjected ~30 strength-trained individuals to a battery of performance assessments before and after 7 days of a low carb [ketogenic] diet.  Usually I would’ve stopped reading at this point because 7 days is too short.  But there were some nuances in the way this particular study was designed which piqued my interest.

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Sarcopenia has little to do with aging

It has to do with the duration of time spent being sedentary.

They say a picture is worth a thousand words, but luckily enough today you get both.

Sarcopenia: “poverty of flesh,” or the age-induced loss of skeletal muscle mass, strength, and function = reduced quality of life.  Sorry old-timers, but I hereby officially revise the definition from “aging-induced” to “sedentary-induced.”  Herein, I present evidence that sarcopenia is not a phenomenon of aging per se, but rather of disuse atrophy.  Dear Webster’s & Britannica, please revise accordingly.

Skeletal muscles: use ‘em or lose ‘em #TPMC

Thanks to Julianne Taylor & Skyler Tanner for directing me to these images.

divide and conquer

Exhibit A. Chronic exercise preserves lean muscle mass in masters athletes (Wroblewski et al., 2011)

This study evaluated “high-level recreational athletes.”  “Masters” just means they were over 40.  And “high-level” doesn’t mean “elite,” it just means they exercised 4-5 times per week.  These weren’t super-obsessed gym rats
 it’s probably who I’ll be in 7 years [sigh].

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