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Run Long, Run Healthy Weekly Roundup — February 24, 2022

Your weekly guided tour of the best new research and articles on running from around the web.

Each week, Boston Marathon winner Amby Burfoot, also the world’s most experienced running editor, curates the latest and most useful content on running and health from around the internet. “I spend hours finding the best new research and articles, so you can review them in minutes.”

THIS WEEK: How running improves your sex life. More on pyramidal training vs polarized. Tune your training to your muscle-fiber type. The latest on beets and performance. To avoid RED-S, focus on carbs. How diet can improve your race times. Why and how to rotate your running shoes. A new warmup routine. This mouthguard claims to make you a better runner. More.

Will running improve your sex life?

The answer is a relatively confident “Yes,” and the reasons are simple to understand. Why wouldn’t running improve your sex life when it improves your fitness, weight, vigor, emotional state, and so on? The author ignored a couple of negative aspects, such as the possibility that heavy training (overtraining) might reduce libido and function, but generally, her research and conclusions are reasonable. “In sum, more exercise suggests greater sexual performance and satisfaction.” More at Outside Online.

More on that training question: pyramidal versus polarized

I covered this in some depth last week, but the topic has attracted a lot of additional interest, especially from Sweat Science writer Alex Hutchinson. Also, physiologist co-author of the Pyramid paper, Andy Jones, described the general distribution of Eliud Kipchoge’s training. Jones tested and advised Kipchoge in the buildup to his sub-2-hour marathon efforts. Here Hutchinson offers his own overview, which seems largely consistent with mine. More at Outside Online.

Some men need pelvic floor therapy, too

Although, statistically, pelvic floor problems strike females much more, especially those who have delivered children. The most interesting part of this article is the argument that pelvic floor exercises and therapy can contribute to overall core stability, which might improve performance and lower injuries. Though that is not proven. More at Triathlete.

How muscle fiber types—slow versus fast twitch—affect your training

You can’t do much to change your muscle fiber ratio—or “myotype”—but you might be able to train more effectively and avoid injuries if you understand your type. A Dutch researcher, Eline Lievens, just finished her Ph.D. on this topic and shares her insights in a fantastic Twitter thread and free, downloadable PDF. A couple of key points: Those with a preponderance of fast-twitch fibers are more likely to have overtraining problems, and they need more recovery time when doing interval workouts. Slow-twitch runners can do their intervals with slower recoveries. I only wish someone had told Dr. David Costill in 1968 that it wasn’t cool to dig into my calf and extract muscle tissue, but I suspect I’ll get over the shock and pain sometime soon. More at the University of Ghent (the free, 77-page PDF in English).

The latest on beetroot (beets) and endurance performance

Beets are called “beetroots” in the United Kingdom, where much of this research started. But there’s no difference between the two—both are large globes of bright-red vegetables that grow under the soil. Beets remain an active research area as they have often (but not always) been found to improve endurance performance. Here one study found no physiological benefit among a group of trained female cyclists who consumed beet juice, though they did record a lower perceived effort. One positive sign: With beets, more than 25% of subjects required 3% less vo2 max at top power output. In a different study of male and female runners who raced 2000 meters, those on beets improved significantly more than non-beet subjects, and entirely in the second kilometer (4- to 5-second difference in second km times). More at Applied Sciences.

To avoid RED-S, count your carbs, not just your total calories

There’s a lot of attention on Low Energy Availability and Relative Energy Deficiency in Sports (RED-S, which used to be Female Athlete Triad). Maybe too much. Because it’s not just about Low Energy (the calories); it’s about the source of those calories. In other words, if you’re raising your calorie intake with a relatively high-fat diet, you might still be in trouble. Because Carbs count! Here Louise Burke, basically everyone’s choice for top sports nutrition researcher, shows that a low carb, high-fat diet (with ample total calories) creates a “small yet unfavorable iron, immune, and stress responses to exercise.” Conclusion: “Therefore, short-term restriction of CHO, rather than energy, may have greater negative impacts on athlete health.” More at Medicine & Science in Sports & Exercise.

More from Louise Burke: How your diet can “counter-performance constraints”

All runners, especially marathoners and ultramarathon runners, understand that they need optimal fueling, fluids, and mental acuity to achieve their race goals. You probably know a lot about carbs, sports drinks, and caffeine to cover these three big domains. Here’s more, from the best possible author, and it’s all free, full text with some helpful infographics. Burke says there’s still a lot of “contention” around hydration strategies. Her position: “A unifying model proposes that some scenarios require personalized fluid plans while others might be managed by an ad hoc approach (ad-libitum or thirst-driven drinking) to fluid intake.” More at Experimental Physiology.

New warmup routine: Roll your feet

Here’s one of those “3 secrets” articles where the last 2 are fairly lame and easy to skip. However, the first strategy is something I haven’t tried before, and it has no obvious drawbacks. So of course I’ll be doing it very soon. I won’t tease you anymore. The unnamed author suggests: Use a tennis, lacrosse, or golf ball to roll your feet before running. The claim: “Rolling your feet before running loosens muscle tissue, increases range of motion, and boosts blood flow.” Whereas “Running with stiff [non rolled] feet can make your heel strikes more intense, which risks impact-related injuries.” More at Runner’s Tribe.

Why and how to rotate your running shoes

There are two somewhat contradictory rules for running shoe selection: 1) When you find a shoe that works, stick with it; and 2) Rotate your running shoes. The rationale behind the first is obvious: If it ain’t broke, don’t fix it. The second is a bit more hypothetical but does have modest evidence to support it. The rationale in this case: It’s good to expose your feet and legs to slightly different conditions to allow them to recover, and also to allow for different muscle activation and growth. This article suggests a rotation scheme based on your days/week of running and weekly mileage. The following linked article actually offers you a Shoe Rotation tool. I’m a bit skeptical of that, but I like the idea of rotation as long as one of your most frequent shoes is Old Reliable. More at Run Repeat.

A mouth guard claimed to have “a positive biophysical effect” on your running

Through the years, various mouthguards have been claimed to improve running function in one way or another. Here’s a new one, from tests on a single-subject female triathlete. The device is termed an “intraoral jaw-protruding splint,” and there are some images on this webpage. In the case study, researchers compared a control device with ones that protruded the jaw by 30 percent or 50 percent. The protruding splints were found to decrease oxygen consumption and energy expenditure, while slightly changing stride length and frequency. Conclusion: “Wearing a jaw-protruding splint can have a positive biophysical effect on running-performance-related parameters.” More at Int J of Sports Physiology & Performance.

SHORT STUFF you don’t want to miss


“She was a vixen when she went to school;

And though she be but little, she is fierce.”

—William Shakespeare, A Midsummer Night’s Dream

That’s it for now. Thanks for reading. Stay well, and see you next week.