Quick Thoughts on the Science of Lifting

This edition of quick thoughts looks at hypertrophy and muscle length, the final frontier, long-term dilemmas, and the interactions of illness and intense training. 

Range of Motion, Muscle Length, and Hypertrophy

Believe it or not, for a long time one of the top hypertrophy studies around involved bird wings. Back in the early 90s a couple of University of Texas researchers took a bunch of quail and put their wings under a loaded stretch for hours at a time. After a few weeks of what sounds a bit like medieval torture, the birds were killed and their muscles examined. The results were that the birds’ wing muscles grew in relation to stretch duration and load. These studies were part of the inspiration behind the Doggcrapp method’s stretching protocols. Cumulative studies have determined that an exercise has to have a certain amount of stretch and loading in order to elicit hypertrophy, though not much more has been determined. I think the experience of most lifters backs this idea up.

Just this past year, a team of UK researchers took a closer look at the topic. They collected a mixed-gender group of thirty-one students with little or no leg-training experience and had twenty-one of them hit the leg extension machine for a little while (the remaining seven were a control). While resistance was matched to provide relatively similar force production, the ranges of motion for the fourteen experimental subjects were different. While all the students exercised through a 50-degree range of motion, half did so from the top of the lift (moving the leg between full and partial extension) while the other performed the bottom portion of the lift (from 90 degrees to 40 degrees). To allow for changes in the moment arm, the top lift group lifted about 80 percent of the 1RM, while the bottom group trained at 55 percent. This meant both groups were working about equally as hard despite having different difficulties for their respective movements.

For all twenty-one lifting participants, their muscles stretched about three inches from start to completion of a lift. When the study was wrapped up, the researchers found a few findings in favor of the bottom-lifters. The 90-degree lifters had greater increases in muscle cross-section (especially near the knee), fascicle length, IGF-1 production, and strength. They also kept their gains longer. The authors speculate that a combination of greater muscle activity, metabolic and mechanical stress, and greater IGF-1 production.

The takeaway is that this is another point in favor of an emphasized range of motion being helpful during a dynamic lift. Which is probably something everyone reading this already employs, but it’s nice to know a little more about why this might be the case.

Abstract available here (full text is pay-walled): http://www.ncbi.nlm.nih.gov/pubmed/23625461

Muscle and Microgravity

Roughly up through the 90’s, the best bankroll in town for strength science was NASA. In fact, the Ploutz study that demonstrated muscle fibers are selectively recruited in response to load was a NASA-sponsored gig.

The reason for NASA’s concern is pretty simple: the near-zero gravity environment of space is hell on the bones, skeletal muscles, and tendons. Without the constant stress of gravity, the metabolic activities of these structures change, resulting in soft tissue atrophy and a diminished bone density. It’s worse than being confined to bed for an equivalent period of time—you might’ve seen pictures of returning astronauts who seem to be struggling during their first walk across the tarmac after landing.

NASA isn’t necessarily concerned with the best methods for keeping astronauts healthy. Instead, the space agency seeks the most efficient methods. There are two things a shuttle or station crew doesn’t have much of: time and cabin space. Space flights are a little too expensive to serve as floating fitness centers, and the vehicles they require jam every square inch of surface area possible with needed instrumentation and systems (and not to mention extra mass changes propulsive and navigational variables).

Efficiency is doubly important because the same structural wasting that hits space travelers also weakens the cardiovascular system to a similar extent. This means that engineers not only have to figure out how to fit a resistance lifting platform onto a pod or shuttle, but also a zero-g treadmill that literally pulls you into the running deck, or anything else that’ll keep astronauts from infirmity.

It’s a tough battle, with the general consensus being that we don’t yet know what we need to know for physically preserving space travelers during extended space flights and orbits. If you’re interested in the chronic physical damage of space flight, I recommend Michael Joyner’s readable commentary “Wasting Away in Mars-Aritaville,” The Journal of Physiology, Volume 588, Issue 21, page 4071, November 2010.

Available online at: http://onlinelibrary.wiley.com/doi/10.1113/jphysiol.2010.198861/full

The Longitudinal Problem

I’m going to speak generally on this one. The biggest limitation on research right now is time. It’s almost impossible to conduct thorough longitudinal studies on humans, especially when it comes to strength and conditioning. If you want truly long-term bio/health studies of any sort, for the most part you have to go epidemiological. This is anathema to the bleeding-edge needs of strength and conditioning research.

We can roughly divide strength and conditioning studies into two camps: lab-based studies (such as you’ll find in most university studies) and “real-world” studies that use existing, organized athletic groups as subjects. As you’d expect from work done at research schools, undergrad students are the most common guinea pigs. While using students can lower costs by reducing recruiting and remuneration costs (somewhere, right now, there’s a broke first-year year student thinking getting biopsied for ten bucks is a steal), students are an uncontrollable group prone to wild lifestyle swings and are largely unreliable for studies lasting more than a few weeks. When you consider how long it can take to adapt to training or a dietary regimen, the problem is easy to spot. Think about how many studies say something promotes protein synthesis, and how few talk about annual changes in muscle development.

The problems aren’t solved when you use teams as a subject, assuming your performance measures for successful competition are easily measured. For example, a throwing or running event easily demonstrates performance benefits/deficits in training, though that can be harder to pull from a complex team sport like football.

Assuming you’re tracking a simple, quantifiable sport, to get reasonable access and control over high-level athletes, you usually have to be their coach, which makes it difficult to blind the studies. There’s also the problem of creating control/experimental groups and restricting variables—it’s tough enough to run a single team, much less two at the same time. And who knows if your key players are chugging beers before games or going the PED route. Of course, if a team’s willing to hand itself over to a shadowy researcher with unproven methods and omniscient awareness, then you can get something going.

This isn’t to say the feat is impossible in any context. The researcher-coaches of the Eastern Bloc exerted this level of control (and I’ll assume the Chinese do the same), and trusted strength and conditioning coaches in the west can approximate this. And thinking of the earlier section on astronauts, the men and women of the International Space Station spend a good bit of time drawing each other’s blood, taking tissue biopsies, and running ultrasound scans during their months in orbit.

Exercise and Illness

Flu season is nearly upon us, and there’s plenty of information out there to about how best to keep these viruses, sinus infections, and other bugs at bay. In fact, I came across a public health bulletin the other day that called exercise an unequivocal net positive when it came to keeping contagious illness at bay. The facts, however, point to a more complicated story. People who exercise generally contract fewer bugs, though we’re talking small differences usually. Elitefts™ readers are more worried about immediate impacts of training, i.e., should you stop training when your spouse gets the flu, and what training during illness does to your recovery.

First, it’s important not to confuse “immune activity” with “illness prevention/reduction,” for the same reason you can’t use “protein synthesis” as a synonym for “long-term muscle growth.” Muscle damage lights up the immune system (something has to clean up after all the tissue damage) but whether it improves or degrades our ability to prevent/fight off infection remains to be seen. Overall body temperature elevates during exercise, but there’s nothing to suggest it does so effectively in the infected areas of the body, e.g., the human rhinovirus prefers cooler climates, which is why it sets up shop in the respiratory system which stays cooler than the rest of the body. Exercise stress may dampen inflammatory signals, but it’s hard to tell if it’s helpful in immediately fighting a microbial intruder, or if it’s counterproductive to resisting infection.

Where does that leave us? A recent position paper by the Exercise Immunology Review essentially says, “It’s probably best not to train like a moron.”

No surprise that a line of outcome-oriented research on this topic falls into the “very difficult to study” category. You either have to expose volunteers to various viruses and bacteria, or follow trained subjects around, wait for them to get sick on their own, and hope you could identify and document infection parameters effectively. No surprise that results are all over the place, testing methods are wanting, and there aren’t many confirming experiments for promising prior research. Worse for the elitefts™ crew is that when studies come up with immediate take-home results, they usually feature cardio as the main form of exercise.

The results of a smattering of studies on people, rodents, and tissue samples suggest some items of interest:

  • Heavy curls and lateral raises after vaccination can boost antibody production if the vaccine itself doesn’t trigger a strong response or if the dose is underpowered
  • Exercise’s short-term dampening of T-cells might be reversed somewhat by carbohydrate ingestion
  • Moderate cardio doesn’t seem to help or hinder people deliberately infected with colds
  • If exercise does make infection seem less onerous, it might be because it makes the rest of your life more bearable so the cold doesn’t seem so bad
  • If you start exercising during the early stages of the flu, it might help some, though not as much as if you’d been exercising frequently
  • Some of the same factors that cause exercise-induced immune depression are also responsible for beneficial training responses

For an overview of the debate, I recommend the following review by Michael Gleeson, who is one of the top researchers in the field: “Immune Function in Sport and Exercise.” Journal of Applied Physiology August 2007 vol. 103 no. 2 693-699.

Available online at: http://jap.physiology.org/content/103/2/693.long