Tag Archives: muscle

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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Energy Balance > CICO

The regulation of energy balance is a long-term process, and it can’t be maintained by counting calories on a day-to-day basis.  Taubes once wrote that exercise doesn’t cause weight loss because it builds up an appetite, so you end up sucking down a Starbuck’s Jumbo Calorie Bomb on the way home from doing Yoga at the gym.  This is probably somewhat true, but this little gem from 1955 exposes some very interesting nuances.

Edholm(Edholm et al., 1955)

These researchers rigorously measured food intake and did a comprehensive assessment of energy expenditure during a wide variety of activities – lying down, standing, walking, gun cleaning, stair climbing, dressing, etc., etc.

Divide and conquer

The individual differences: big people expend more energy on life.  most of the time.

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40 years ago a group of researchers turned ketosis into poetry.

But first, a brief primer.  In red.

“The glucose muscle-sparing effect of fat-derived fuels” 

or, the Randle Cycle 2.0.  it’s like a course in life enhancement.

Part I.  Intermediary metabolism

The glucose-fatty acid cycle
The Randle Cycle, as originally proposed, states that fatty acid oxidation inhibits glucose oxidation.  This is good because during starvation, every tissue than can survive on fatty acids instead of glucose should do so, sparing as much precious glucose as possible for the brain.

The glucose-sparing effect of fat-derived fuels
A critical vital horcrux to this is in the oh-so-humbly-disguised phrase “fat-derived fuels.”  The fat-derived fuels are ketones, and they are rescuing the brain from starvation (ie, neuroglycopenia); they do so by supplementing glucose as a fuel source.  Ketones are good at this; many tissues are happy to oxidize ketones when they are available.

The glucose muscle-sparing effect of fat-derived fuels
Ketones are derived from fat.  During prolonged starvation, glucose comes from skeletal muscle amino acids (eg, alanine).  Ketones spare glucose.  Thus, ketones spare muscle.  QED.

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Milo of Croton vs. concurrent training

Lesson 1.  Milo of Croton

Every day since a very young age, Milo would drape his calf over his shoulders and do his daily exercises.  As his calf grew, so did Milo’s strength.  Many years passed and by the time of the Olympic games, Milo’s calf had become a full-grown bull and Milo’s strength became unparalleled in all the land (or so the story goes).

This is how strength-training works.  Increasing the amount of weight you lift progressively, consistently, and frequently makes you stronger.

Lesson 2.  Concurrent training

Resistance training builds muscle and strength.  Endurance exercise is good for the heart, burns fat and muscle, but doesn’t make you stronger.  Endurance exercise hinders the gains reaped from resistance exercise, not vice versa.  Interpretation: runners should lift; lifters shouldn’t run (sprints don’t count).

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Exenatide and tapeworms, Op. 116

The great Dr. Schoeller can polish a turd like no other.  Dale Schoeller’s claim to fame is his extensive work on one of the best ways to measure total energy expenditure in free-living individuals: doubly-labeled water.  In doubly-labeled water, subjects drink stable isotope-labeled water; instead of hydrogen + oxygen = H20, the stable isotope-labeled water is deuterium + oxygen-18 = D218O.  Deuterium is excreted just like hydrogen, in water as urine & sweat.  Oxygen-18 is excreted just like oxygen, in water and carbon dioxide.  So the subjects lose deuterium & oxygen-18 in water at equal rates, but only oxygen-18 in carbon dioxide; so this technique basically measures carbon dioxide production, which is proportional to energy expenditure.  Clever. 

Being that Schoeller practically invented the technique, his interpretation of these total energy expenditure data are not flawed, but that’s not where he went astray.

Alterations in energy balance following exenatide administration (Bradley et al., 2012)

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Nutrient timing, Op. 101

There is no longer a debate on the value of protein supplements for exercisers.  Now I’d like to make the case for protein timing, or more specifically the value of pre-workout protein supplementation.

Cribb and Hayes (2006) examined the two extremes of protein consumption: immediately before and after working out (“PRE-POST”) vs. 8 hours before and 8 hours after working out (early morning and late evening; “MOR-EVE”).  Each protein shake contained 40 grams protein, 43 grams glucose, and 7 grams creatine.  The subjects were recreational weight lifters, an interesting choice in terms of data interpretation.  I.e., novices are expected to see much greater gains from beginning a new exercise program than experienced exercisers.  Thus, any difference between the groups is expected to be greater.  For example: compare the difference between 5 and 10 to that of 1 and 2.  The relative difference (2x) is the same in both cases, but the absolute difference between 5 and 10 is significantly greater and thus easier to detect.  This stacked the odds against seeing a difference between treatments.  The advantage is that experienced lifters know how to do a high intensity workout, and the results are applicable to people who already exercise.

Notes on the wonders of energy balance:
The protein shakes added ~272 kcal to their total food intake, which caused them to eat less during the rest of the day.  Interestingly, food intake declined by 74 kcal in the PRE-POST group and over twice as much (172 kcal) in MOR-EVE.  Food intake declined in MOR-EVE because the extra calories were just floating around in the bloodstream and thus available to register lots of “excess energy” to the brain.  But the increase in muscle was 2x greater in PRE-POST than MOR-EVE; thus, the extra calories in PRE-POST were immediately invested in laying down new lean mass and therefore weren’t around to signal “excess energy” to the brain.

energy in energy out is bollocks

How the “energy in” is handled is critically important.  With regard to an energy excess, dessert before bedtime is stored as fat but the same amount of calories from protein before exercise are invested into muscle.

A calorie isn’t a calorie because body composition matters.

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