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Fitness: The 4 Laws of Muscle

STORY AT-A-GLANCE:

  • Muscle is lost far more easily and quicker than it’s built, so finding ways to continuously promote and maintain your muscle mass is really crucial, especially as you get older. Anytime you’re sick or hospitalized, having reserve muscle mass will also improve your chances of survival
  • Research shows elderly subjects can add 2.9 pounds of muscle in six months by strength training and taking a twice-daily protein supplement (15 grams per serving for a total of 30 grams per day)
  • However, even healthy young subjects in their 20s can lose 3.1 pounds of muscle mass in a single week of bedrest. You can lose 2.5% of your total muscle mass in the first two weeks of bedrest. By day 23, you can have lost up to 10% of your quadriceps’ muscle mass
  • You break down and rebuild 1% to 2% of your muscle mass each day, so you completely rebuild yourself every two to three months. Dietary protein is an essential component to build and maintain muscle mass, and older individuals have higher protein requirements than younger people
  • Exercising before you eat boosts your muscles’ sensitivity to protein signals, allowing you to optimize muscle building

While many tend to think about strength training as a form of vanity — developing a six-pack and a bulging “muscle-man” look and whatnot — building and maintaining muscle is actually a lifesaving strategy, and an imperative for a long and healthy life.

Anytime you’re sick or hospitalized, having reserve muscle mass will improve your chances of survival,1 and as I’ll discuss below, you can lose significant amounts of muscle in a single week of bedrest.

Muscle is lost far more easily and quicker than it’s built, so finding ways to continuously promote and maintain your muscle mass is really crucial, especially as you get older.

So, just how do you do that? This topic was addressed in a 2017 article2 by Alex Hutchinson in which he interviews Luc van Loon, a professor of exercise and nutrition at Maastricht University in the Netherlands.

Elderly Need More Protein to Build Muscle Mass

In 2012, van Loon published research3 showing elderly subjects (ranging in age from 77 to 79) could tack on 2.9 pounds of muscle in just six months by strength training and taking a twice-daily protein supplement (15 grams per serving for a total of 30 grams per day).

Participants that trained but didn’t take extra protein saw no improvement in lean body mass, even though they did get stronger. In conclusion, van Loon and colleagues noted that:4

“Prolonged resistance-type exercise training represents an effective strategy to improve strength and physical performance in frail elderly people. Dietary protein supplementation is required to allow muscle mass gain during exercise training in frail elderly people.”

You Lose Muscle MUCH Faster Than You Build It

Shortly thereafter, one of van Loon’s students completed a study5 showing otherwise healthy young subjects in their 20s lost 3.1 pounds of muscle mass in a single week of bedrest. As noted in this study:

“Short (<10 days) periods of muscle disuse, often necessary for recovery from illness or injury, lead to various negative health consequences … Ten healthy, young males (age: 23 ± 1 years …) were subjected to 1 week of strict bed rest …

Bed rest resulted in 1.4 ± 0.2 kg lean tissue loss and a 3.2 ± 0.9% decline in quadriceps CSA [cross-sectional area]. VO2peak and one-repetition maximum declined by 6.4 ± 2.3 and 6.9 ± 1.4% respectively.

Bed rest induced a 29 ± 5% decrease in whole-body insulin sensitivity. This was accompanied by a decline in muscle oxidative capacity, without alterations in skeletal muscle lipid content or saturation level, markers of oxidative stress, or capillary density. In conclusion, 1 week of bed rest substantially reduces skeletal muscle mass and lowers whole-body insulin sensitivity …”

Other studies have come to similar conclusions. For example, a 2015 review6 in Extreme Physiology & Medicine notes research showing you can lose 2.5% of your muscle mass in the first two weeks of bedrest. By day 23, you can have lost up to 10% of your quadriceps muscle mass. As explained in this review:7

Skeletal muscle mass is regulated by a balance between MPS [muscle protein synthesis] and MPB [muscle protein breakdown]. In a 70-kg human, approximately 280 g of protein is synthesized and degraded each day. The two processes are linked … as facilitative or adaptive processes, whereby MPS facilitates (allows modulation of muscle mass) and MPB adapts (limiting said modulation).

When exposed to an anabolic stimulus, MPS rises. MPB rises too, but to a lesser amount, resulting in a net synthetic balance. In response to an anti-anabolic stimulus, MPS decreases and MPB decreases to a lesser degree, resulting in a net breakdown.

The interaction between critical illness and bed rest may result in greater muscle loss compared to bed rest alone. The musculoskeletal system is a highly plastic and adaptive system, responding quickly to changing demands. Relatively short periods of immobilization decrease MPS, with no effect on MPB.

Furthermore, this altered balance is relatively resistant to high dose amino acid delivery … Immobilization has significant effects on peripheral muscle aerobic capacity, contractility, insulin resistance and architecture.

Microvascular dysfunction occurring in severe sepsis is associated with immobilization and may have an additive effect on reducing MPS. In critically ill patients, MPS is reduced even with nutritional delivery, with increased MPB seen, leading to a net catabolic state and thus muscle wasting.”

Key Lessons

As noted by van Loon in the interview, “you can mess up a lot more in one week than you can improve in six months of training.”8 He now believes that understanding how we lose muscle is just as important as understanding how to build it. In 2017, van Loon presented several “key lessons” learned for how to build and prevent the loss of muscle mass, which included the following:9

“You are what you just ate” — Research10 looking at post-prandial protein handling and amino acid absorption shows 55.3% of the dietary protein of a given meal is in circulation within five hours after eating, which significantly increases muscle protein synthesis. In other words, “you are what you just ate.” As noted by the authors:

“Ingestion of a single meal-like amount of protein allows ~55% of the protein derived amino acids to become available in the circulation, thereby improving whole-body and leg protein balance.

About 20% of the dietary protein derived amino acids released in the circulation are taken up in skeletal muscle tissue following protein ingestion, thereby stimulating muscle protein synthesis rates and providing precursors for de novo muscle protein synthesis.”

In his article, Hutchinson writes, “Overall, van Loon points out, we break down and rebuild 1 to 2 percent of our muscle each day, meaning that you completely rebuild yourself every two to three months.” The take-home message here is that protein is an essential dietary component for building muscle.

Exercise boosts sensitivity to protein signaling — While protein-derived amino acids are building blocks for muscle, they also act as signaling molecules that trigger muscle growth. Leucine is a particularly potent signaling agent, although all of the amino acids are required to actually build the muscle.

Research11 suggests healthy young adult men “max out the protein synthesis signal from a given meal” at a dose of 0.24 grams of protein per kilogram of total bodyweight, or 0.25 grams of protein per kilogram of lean body mass, Hutchinson notes.

The current U.S.-Canadian recommended dietary protein allowance is 0.8 g/kg/d (0,36/grams/pound/day). Healthy older adults may require a greater dietary protein intake much higher than their younger peers or ~1.20 g/kg/d or .55 grams/pound/day. According to this study:

“Our data suggest that healthy older men are less sensitive to low protein intakes and require a greater relative protein intake, in a single meal, than young men to maximally stimulate postprandial rates of MPS [myofibrillar protein synthesis].

These results should be considered when developing nutritional solutions to maximize MPS for the maintenance or enhancement of muscle mass with advancing age.”

Importantly, additional research described in Hutchinson’s article12 demonstrated that exercising before you eat boosts your muscles’ sensitivity to protein signals so, in essence, “if you exercise first, you’re more of what you just ate.”

Inactivity desensitizes protein signaling — On the flipside, your muscles lose their sensitivity to protein signaling from inactivity. It is not just about pushing more protein. That is a nearly worthless strategy for muscle building if you fail to integrate the exercise element.

I believe the best exercise strategy is one that activates the microvascular component of muscle stem cells that tends to become depleted with age. That is why I strongly recommend blood flow restriction training.

What’s more, you don’t lose muscle at a steady rate; rather, most of it is lost during short periods of significant inactivity, such as bedrest after an injury or illness. Hutchinson writes:13

“Van Loon advocates some simple fixes — like never, ever feed someone in a hospital bed unless it’s absolutely necessary. Make them get up, and ideally make them shuffle down the hallway to get food. Same for watching TV.

Even this tiny amount of muscle contraction, he says, will enhance muscle synthesis when the patient eats. Similarly, since you don’t eat as much when you’re in bed, the proportion of protein in the meal should be higher to ensure sufficient muscle synthesis signals.”

In cases where the patient is completely immobile, research14 shows the twice-daily application of neuromuscular electrical stimulation can reduce muscle loss by 3.5%. Neuromuscular electrical stimulation can also be used on comatose patients to limit muscle atrophy.15

Properly chew your food to boost protein absorption — Research has also shown ground beef protein absorbs more rapidly and readily than steak, with 61% of the protein from ground beef going into circulation within six hours of ingestion, compared to 49% of the protein from steak. The take-home message seems to be that breaking up the meat by thoroughly chewing it before swallowing might be helpful.

Defy Aging by Improving Your Muscle Mass

In my February 2020 interview with Ben Greenfield, author of “Boundless: Upgrade Your Brain, Optimize Your Body & Defy Aging,” we discuss the importance of strength training and getting the appropriate amount of protein to build and maintain your muscle mass and optimize mitochondrial density and biogenesis.

In summary, Greenfield recommends a fitness program that includes the following types of exercise in order to target the main pathways involved in health and aging:

High-intensity interval training once a week to boost mitochondrial density and biogenesis — Brief spurts of exercise followed by longer rest periods. Greenfield recommends a 3-to-1 or 4-to-1 rest-to-work ratio.

Muscle endurance training two to three times a week to improve lactic acid tolerance — An example is the classic Tabata set, which has a 2-to-1 work-to-rest ratio.

Longer training sessions twice a week to improve your VO2 max — To target and improve your VO2 max, you’ll want your training sessions to be longer, about four to six minutes in duration with four to six minutes of recovery in between, for a 1-to-1 work-to-rest ratio.

Examples include The New York Times’ seven-minute workout16 and bodyweight training done in a fast explosive manner or with a very light medicine ball, sandbag or kettle bells.

Long walk once a week to improve your stamina — Greenfield recommends taking a 1.5- to three hour-long walk, bike ride or paddle session — anything where your body is engaged in chronic repetitive motion for a long period of time — preferably in a fasted state. Alternatively, do 20 to 30 minutes of fasted cardio followed by a cold shower.

Super-slow weight training once or twice a week to improve muscle strength — Alternatives include elastic band training systems and blood flow restriction (BFR) training, which is my personal favorite. You can also combine BFR with super-slow training.

Sources and References:

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