New Research — ϲ Wed, 11 Dec 2024 13:52:10 +0000 en-US hourly 1 https://wordpress.org/?v=6.6.2 Exercise Science Professor Kylie Harmon Investigates Ability to Preserve Muscle Mass and Strength During Immobilization /blog/2024/12/11/exercise-science-professor-kylie-harmon-investigates-ability-to-preserve-muscle-mass-and-strength-during-immobilization/ Wed, 11 Dec 2024 13:52:10 +0000 /?p=206191 Exercise Science Professor Kylie Harmon with student Rylie DiMaio.

Department of Exercise Science Assistant Professor Kylie Harmon (right) and exercise science student Rylie DiMaio review a sonogram of DiMaio’s leg muscles to provide a baseline for Harmon’s research on preserving muscle strength during immobilization.

Mind over matter.

, an assistant professor in the in the Falk College of Sport and Human Dynamics, has always been fascinated by this deep-rooted idea that a person could control a physical condition with their mind.

More specifically, she wondered if a person could use their mind to preserve muscle mass and strength during a prolonged period of immobilization. For Harmon, turning this idea into actual research was sparked by where researchers used neuromuscular electrical stimulation on muscles immobilized in a cast to preserve leg strength and mass. Surprisingly, mass was preserved, but strength was not.

Harmon’s research found that given the role of the nervous system in immobilization-induced weakness, targeted interventions may be able to preserve muscle strength but not mass, and vice versa. Though preliminary, her findings highlight the specific nature of clinical interventions and suggest that muscle strength can be independently targeted during rehabilitation.

Harmon’s innovative research, which was conducted over several months and with nearly 40 participants, was by the peer-reviewed scientific journal Experimental Physiology.

We sat down with Harmon to learn more about her research, most surprising findings, and next steps. Here’s that discussion:

Exercise Science Professor Kylie Harmon

Kylie Harmon

Q: What did you learn from the previous research on this topic, and how did that frame what you wanted to accomplish with your research?

A: Those researchers saw that daily muscle stimulation helped to maintain muscle size, but didn’t impact muscle strength. In much of my work, I was using interventions that improved muscle strength but had no impact on muscle size. I had some experience with action observation and mental imagery, which are neural intervention techniques in which a person observes muscular contractions or thinks about performing muscular contractions without actually doing so. These have been shown to be effective for strength gain or preservation, as they activate the neuromuscular pathways responsible for strength production. However, they don’t impact muscle size.

So, I thought it would be interesting to directly compare these two interventions–neuromuscular electrical stimulation versus action observation + mental imagery–to see if previous findings held up. We decided to design a lower-limb immobilization study with one group performing daily action observation + mental imagery to preserve strength, and another group performing daily electrical stimulation to preserve muscle size. The goals were twofold: 1) To further demonstrate that strength and size are distinct qualities and need to be addressed with specific interventions and 2) To hopefully improve rehabilitation outcomes by preserving size and strength during immobilization.

Q: Once you established your goals, how did you determine your research methods?

A: It took several months and a lot of teamwork to determine our methods. I relied heavily on existing literature to determine how to best implement lower-limb immobilization, what leg braces to use, what joint angle to immobilize at, and how long immobilization was needed before we would observe decreases in strength and size. I reached out to authors of my favorite papers to ask them about their methodologies, such as how to design an appropriate action observation + mental imagery intervention and what stimulation devices to buy.

Once I had a good idea of the game plan, I presented the idea to my mentors and collaborators to get their feedback. Finally, we developed a sizable research team to help with the project: three Ph.D. students, three M.S. students, four physical therapy students, and five undergraduate students. It was very much a team effort!

Exercise Science student Lydia Van Boxtel.

As demonstrated by exercise science student Lydia Van Boxtel, the subjects in Kylie Harmon’s study need to learn how to use crutches after being fitted with the leg brace.

Q: Can you describe the process of gathering your data?

A: We screened 117 interested people, and when all was said and done, we had 39 individuals fully participate in the study. Prior to the immobilization week, we tested muscle strength, muscle size and the ability of their brain to activate their muscles. We then had physical therapy students fit participants with a leg brace and crutches and show them how to navigate a variety of obstacles–opening doors, using stairs, sitting and standing.

During their week on crutches, participants had to wear accelerometers around both ankles so we could ensure that they were actually using the brace and crutches when away from the lab. We gave them a shower chair to assist in bathing, as they had to keep the brace on at all times except during sleep. We asked them to track the food that they ate. We also had a member of the research team call and check in on each participant every day during the immobilization week to make sure they were complying with study protocols and weren’t running into any issues.

In addition to immobilization, one group performed daily action observation + mental imagery using a guided video and audio recording, and another group performed daily neuromuscular electrical stimulation on their thigh muscles with a stimulation device we gave them.

We had participants return to the lab for a post-testing visit and again re-tested their muscle strength, size and neuromuscular function. If they lost strength (which almost everyone did), we had them come back to the lab twice a week for lower body resistance training until they regained their strength. We didn’t want them to leave the lab with weak, small muscles because of our experiment. Not very ethical. We ensured they were recovered and as well. Amazingly, no one dropped out during the leg immobilization, and we had 100% compliance.

To read the full Q&A with Harmon, visit the .

]]> New Research on the Evolution of Sexual Selection in Fruit Flies /blog/2024/11/26/new-research-on-the-evolution-of-sexual-selection-in-fruit-flies/ Tue, 26 Nov 2024 16:15:59 +0000 /?p=205816 New Research Published in Nature,
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Offer New Clues to the Evolution of Sperm
  • ϲ researchers from the Center of Reproductive Evolution published a paper that offers insight into the evolution of giant sperm in male fruit flies and the reproductive tracts of female fruit flies.
  • Long sperm tails have evolved in fruit flies because they are better equipped than shorter sperm for the battle to fertilize eggs and because female reproductive tracts are designed to bias fertilization in favor of longer sperm.
  • In other words, long sperm tails are the cellular, post-mating equivalent of peacock tails.
  • The ability to test the foundations of sexual selection theory, and to develop new hypotheses about the evolution of sexual traits, has been hampered by limited information about the genetics underlying such traits.
(ϲ, NY)…Sperm are the most diverse and rapidly evolving cell type. Why sperm have undergone such dramatic evolution is a mystery that has stumped biologists for more than a century.
To solve this evolutionary puzzle, researchers at ϲ’s  (CRE) have spent decades studying the mating biology of fruit flies. These small and outwardly unremarkable insects conceal a grand reproductive secret inside: giant sperm.
Fruit flies show more variation in sperm length than do the remainder of the entire animal kingdom combined. For example, males of one species of fruit fly, Drosophila bifurca, inseminate their partners with only a couple dozen sperm, each one being a gargantuan 5.8 cm long (about 20 times longer than the female’s body) and rolled up like a ball of yarn.
Investigations by SU’s Center for Reproductive Evolution members, including Weeden Professor of Biology , Professor of Biology , Assistant Professor of Biology  and their students have revealed that longer sperm have been favored by sexual selection, for which the theoretical groundwork was laid out by Charles Darwin in 1871 in his seminal book, “.”
Essentially, long sperm tails have evolved because they are better equipped than shorter sperm for the battle to fertilize eggs and because female reproductive tracts are designed to bias fertilization in favor of longer sperm.
In other words, long sperm tails are the cellular, post-mating equivalent of peacock tails. In fact, a previous publication from the Center for Research Evolution in the journal  showed that fruit fly sperm tails rival pheasant tail feathers, deer antlers, dung beetle horns, lizard dewlaps and others from the hitlist of nature’s sexiest ornaments and most intimidating weapons.
The ability to test the foundations of sexual selection theory, and to develop new hypotheses about the evolution of sexual traits, has been hampered by limited information about the genetics underlying such traits.
However, in a new study by the Center for Reproductive Evolution, in collaboration with scientists from Stanford University, Cornell University, Virginia Tech, and the University of Zurich shines a light on the genetics of fruit fly sperm length and of the female reproductive organ responsible for its evolution.
Their findings, reported in the journal , may advance our understanding of all mate preferences and sexual ornaments. The research team first measured sperm length and the length of the female seminal receptacle (SR), which is the anatomical basis of female “sperm choice,” in 149 species of fruit flies.
After sequencing the full genomes of every one of these species (published in ), the investigators mapped traits onto the fruit fly tree of life to reveal how these interacting male and female traits have coevolved over the last 65 million years.
Next, the investigators conducted a “genome-wide association study” approach to identify candidate genes underlying variation in sperm and SR length in the lab model fly Drosophila melanogaster. Surprisingly, only about 19% of the genes determining variation in sperm length showed biased expression in the testes and are known to code for spermatogenesis.
Most of the identified genes that code for sperm length are primarily responsible for the development and functioning of the central nervous system, in addition to vision and olfaction. Sperm length genetic variation was also correlated with female lifetime fecundity, starvation resistance, and the ability to find food.
In other words, through the evolution of reproductive tracts designed to give males with longer sperm an advantage in the competition to fertilize their eggs, sexual selection has provided females with a means to comparatively shop around for “good genes” – those enhancing survival and reproduction – to pass on to their offspring.
Finally, a complex algorithm (and approximately 15 million hours of computing time on ϲ’s OrangeGrid computing network) was used to identify genes for which the rate of nucleotide sequence evolution significantly correlates with sperm and SR length evolution across the species tree. This approach reinforced the genetic overlap between sperm length and nervous system development and function.
This highly integrative approach holds great promise, not just to expand researchers’ understanding of the evolutionary genetics of sperm, but of fundamental aspects of biodiversity.
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