Leg Day Observer

Air Force exercise study teases the recipe for enhanced performance

New research explores the power of targeted nutrition.

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There’s this oft-repeated line about how working out makes you think clearer — a presumption that pulling deadlifts or hitting cardio in the morning is the best preparation for a productive day. Train then succeed, or miss your pre-office leg day session and bungle the sale. But a recent study shows the mental benefits of working out to be more complicated.

The 12-week study, published in October in the open-access journal Scientific Reports, focused on the ability of United States Air Force airmen to perform physical and cognitive tasks within varying nutritional environments.

The “healthy, fit” airmen were divided into two groups, one receiving a nutritionally-dense supplement shake full of fats, proteins, minerals, and vitamins — and the other getting a placebo that was mostly sugar. The flyboys (and girls) drank their shakes during and after workouts, which were made up of strength, cardio, and high-intensity programs.

Co-author Adam Strang, a human performance research scientist with the U.S. Air Force Research Laboratory, told me that the strength workouts were 45-minute circuits, and that the workouts, in general, had a “focus on body-weight exercises, multi-planar movements” — front, back and side-to-side — and a combo of “upper body push/pull and lower body anterior/posterior chain exercises.” In other words: standard, good gym shit. Subjects were tested before and after the intervention.

There were a couple of significant results. Physical markers, measured as test outcomes at the beginning and end of the study, increased in both groups: airmen got stronger, and performed better on the post-program battery of physical tests than they did at the start, in every category. Placebo subjects increased five of their six physical markers over the course of the study: power, strength and endurance, mobility and stability, heart rate, and lean muscle mass.

Supplemented airmen showed improved blood pressure, and demonstrated a “further improvement” over their placebo counterparts’ results, implying some relationship between physical strength and either the timing or content of the supplements.

In every case, there was a statistically significant positive relationship between exercise, and strength and performance.

Nutrition, brain health, and performance

The cognitive tasks — word tests, memory tests, letter patterns, reaction-time tests — offer a bigger contrast.

While both the placebo and supplement groups improved their cognitive scores, the supplement group, when performing cognitive tasks, achieved an impressive amount of success, measuring improvement in six of eight markers: episodic memory, fluid intelligence accuracy and reaction time, working memory, executive function reaction time and processing efficiency. However, accuracy for short term memory and executive function did not improve.

The placebo group only improved in four. While both groups showed an improvement, it was broader in the supplement group; the authors point out that “the combination of a nutritional supplement with the exercise training intervention selectively extended the benefits of the exercise training plus placebo intervention for some of the cognitive outcomes.” Which all seems like the point of the study.

The placebo group’s success rate on cognitive tasks was impressive enough to be significant and implies that there are mental benefits to working out, irrespective of diet, which sounds about right. And while those benefits are spottier when not supplemented, it’s not a difference of type. In both cases, there’s a positive relationship between exercise and performance — but there’s also one between supplementation, or vitamins, or increased fat, or increased protein, and their effect on exercise and improved mental cognition.

Ultimately, we’re left with a bit of a vague conclusion even if it seems like everything should be cut and dry. The airmen who took protein shakes during and after workouts were stronger, and more alert.

But questions remain: we don’t really know what it is about the shakes that helped. Even in an isolated and controlled study like this one, there are so many factors at play that it’s difficult to isolate what’s behind a clear, positive relationship.

Could it be that the shakes’ micronutrient profile made up the vitamin deficiencies in the airmen’s diets? Or did they have a macronutrient deficit, and the calories in the shakes took them over the top? Could the more nutritious shakes have made the airmen feel more full, or given them a pathway to better sleep, or made the workouts less taxing, even when drunk double-blind? Or was it an issue of meal timing? Since we don’t know what these airmen ate during the study or their health histories, we can’t precisely know what it is about the supplement shakes that helped; all we know is they did.

"It is possible the active supplement closed nutrient gaps."

Strang said nearly all the airmen had “traditional’ American diets,'' meaning high-carb, and that most were no longer living in military quarters and prepared their own meals. The placebo and supplement groups had “similar dietary behaviors,” and the placebo provided what Strang called a “base level of sustenance,” while the supplement “enhanced performance.”

Matt Kuchan, research fellow and brain health scientist at Abbott and another co-author of the study, tells me “it is possible the active supplement closed nutrient gaps,” since the average American diet that the airmen were on is well-documented to have nutrient gaps. He believes, though, the positive effects “resulted from the combination of muscle and brain nutrients,” and that the nutrients in the shake, which are found in healthy foods, would be difficult to replicate in a natural diet.

Which is a recognition of just how many factors go into human nutrition and athletic performance. The study, to its credit, answers real questions about nutrition and offers a rough template for success which we can try ourselves.

The results seem like a prompt for lifters: self-experimentation, or trial and error, is a helpful way to see what works. Trying a week with an intra-workout shake, and another with a post-workout one, and one with nothing and everything else constant is a rough sketch to success; you can test your progress with a crossword puzzle. These dice rolls are how people change.

One wonders what a non-lifting control group of airmen who took supplements and performed both tests could have added. (Kuchan says they strongly considered it.) But the gist here seems like a happy medium: an ideal workout is one that improves mental cognition, and an ideal diet is one that supplements this improvement.

Still, the immediate, utilitarian benefit of improved mental cognition is what makes this feel different. Working out is so replete with health benefits that listing them feels redundant: we all know getting blood flowing leads to better health and metabolism.

But so many of these solutions seem abstract, or just focused on health: we know that working out is healthy, but if we cared we’d work out. Knowing it might make our brains work better, or more efficiently, or more quietly, seems like a victory of a different kind. Maybe that’s a pathway to money, or solving other problems, or inner peace. It’s another good thing and a different one. Anything past that is supplementary.

Leg Day Observer is an exploratory look at fitness, the companion to GQ.com’s Snake America vintage column, and a home for all things Leg Day. Read past editions of Leg Day Observer for more thoughtful approaches to lifting and eating.

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