Nerve and muscle activity vary across menstrual cycle: May help explain higher rates of knee injuries in female athletes
Numerous studies have shown that female athletes are more likely to get knee injuries, especially anterior cruciate ligament (ACL) tears and chronic pain, than their male counterparts. While previous research has focused on biomechanical differences as the main source of these problems, a new study suggests another distinction that could play a role: changes across the menstrual cycle in nerves that control muscle activity. The finding may eventually lead to new ways to prevent knee problems in female athletes.
Matthew Tenan, Yi-Ling Peng, and Lisa Griffin, all of the University of Texas-Austin, and Anthony Hackney, of the University of North Carolina-Chapel Hill, measured the activity of motor units—nerve fibers and the muscles they control—around the knees of female volunteers at various points of their menstrual cycles. They found that these bundles had firing rates that were significantly higher in the late luteal phase, about a week before a woman's next period, compared to earlier in the menstrual cycle. This difference in firing rate could affect the stability of the joint, potentially affecting its susceptibility to injury.
Their poster presentation entitled, "Maximal Force and Motor Unit Recruitment Patterns are Altered Across the Human Menstrual Cycle," will be discussed at The Integrative Biology of Exercise VI meeting being held October 10-13 at the Westin Westminster Hotel in Westminster, CO.
More Than Biomechanics?
Differences in muscle structure around female athletes' knees have typically gotten the blame for disparities in knee injuries between the sexes, especially for athletes who play sports such as soccer or basketball that involve a substantial amount of knee twisting, turning, and jerking, says study leader Tenan. However, he adds, it's been unclear whether other factors, such as differences in motor unit firing patterns, might also play a part. Since female athletes' hormones fluctuate across the menstrual cycle, Tenan and his colleagues decided to investigate whether these changes affect motor unit activity.
Working with seven female volunteers, all between the ages of 19 and 35, the researchers asked these study participants to chart their menstrual cycles using basal body temperature. This method involves taking body temperature every morning upon waking over the course of the menstrual cycle. Because temperature increases slightly after ovulation (the luteal phase), then dips to pre-ovulation temperatures just before the start of a new cycle (the follicular phase), it's possible to track where each volunteer was in her menstrual cycle on any given day.
The researchers also asked each volunteer to visit their facility five different times at various points of the menstrual cycle. At each visit, they inserted a fine wire electrode, no thicker than a human hair, into two muscles around one of each of the volunteers' knees. The women then did knee extensions while the researchers used these electrodes to measure the activity of motor units in those muscles.
Results showed that motor unit firing patterns varied significantly across the menstrual cycle. Most notably, Tenan and his colleagues found that the rate of firing jumped in the late luteal phase compared to rates earlier in the cycle. Though they're not sure whether these results coincide with a difference in knee injury rates at different points in the menstrual cycle—a topic for future research. Tenan notes that changes in motor unit activity could make women more vulnerable to injury in general.
"Our results suggest that muscle activation patterns are altered by the menstrual cycle," he says. "These alterations could lead to changes in rates of injury."
The findings, he adds, could prompt a closer look at the neuroendocrine system in addition to biomechanics as a possible cause for knee injuries in female athletes—potentially leading to new ways to help female athletes avoid these problems.
More information: bit.ly/OrMFtN
Provided by American Physiological Society
- Female hormone cycle affects knee joints (w/Video) Apr 17, 2009 | not rated yet | 0
- Competitive soccer linked to increased injuries and menstrual dysfunction in girls Feb 07, 2012 | not rated yet | 0
- Premenstrual symptoms getting on your nerves? Dec 20, 2007 | not rated yet | 0
- Women's voices remain steady throughout the month Apr 11, 2011 | not rated yet | 0
- Brain memory modifies during female cycle Nov 14, 2005 | not rated yet | 0
- Motion perception revisited: High Phi effect challenges established motion perception assumptions Apr 23, 2013 | 3 / 5 (2) | 2
- Anything you can do I can do better: Neuromolecular foundations of the superiority illusion (Update) Apr 02, 2013 | 4.5 / 5 (11) | 5
- The visual system as economist: Neural resource allocation in visual adaptation Mar 30, 2013 | 5 / 5 (2) | 9
- Separate lives: Neuronal and organismal lifespans decoupled Mar 27, 2013 | 4.9 / 5 (8) | 0
- Sizing things up: The evolutionary neurobiology of scale invariance Feb 28, 2013 | 4.8 / 5 (10) | 14
Pressure-volume curve: Elastic Recoil Pressure don't make sense
4 hours ago From pressure-volume curve of the lung and chest wall (attached photo), I don't understand why would the elastic recoil pressure of the lung is...
If you became brain-dead, would you want them to pull the plug?
21 hours ago I'd want the rest of me to stay alive. Sure it's a lousy way to live but it beats being all-the-way dead. Maybe if I make it 20 years they'll...
MRI bill question
May 15, 2013 Dear PFers, The hospital gave us a $12k bill for one MRI (head with contrast). The people I talked to at the hospital tell me that they do not...
Ratio of Hydrogen of Oxygen in Dessicated Animal Protein
May 13, 2013 As an experiment, for the past few months I've been consuming at least one portion of Jell-O or unflavored Knox gelatin per day. I'm 64, in very...
Alcohol and acetaminophen
May 13, 2013 Edit: sorry for the typo in the title , can't edit I looked around on google quite a bit and it's very hard to find precise information on the...
Marie Curie's leukemia
May 13, 2013 Does anyone know what might be the cause of Marie Curie's cancer
- More from Physics Forums - Medical Sciences
More news stories
In 2008 researchers from the University of Southern Denmark showed that the drug thioridazine, which has previously been used to treat schizophrenia, is also a powerful weapon against antibiotic-resistant bacteria such as ...
Medical research 15 hours ago | 3.7 / 5 (3) | 0 |
Scientists investigating the interaction of a group of proteins in the brain responsible for protecting nerve cells from damage have identified a new target that could increase cell survival.
Medical research 20 hours ago | 5 / 5 (1) | 0
New findings by researchers carrying out experiments at the U.S. Department of Energy Office of Science's Advanced Photon Source (APS) help explain why some drugs that interact with two kinds of human serotonin ...
Medical research 22 hours ago | not rated yet | 0 |
Peptide molecules derived from the body's natural immune system can help boost the body's defence against life-threatening blood poisoning, joint University research has uncovered.
Medical research 23 hours ago | 4 / 5 (1) | 0 |
A new Montréal study conducted by Dr. May Faraj, associate research professor at the Université de Montréal and invited scientist at the IRCM, along with her research team and medical collaborators, shows ...
Medical research 23 hours ago | not rated yet | 0 |
Big names in medicine are set to give an upbeat assessment of the war on AIDS on Tuesday, 30 years after French researchers identified the virus that causes the disease.
5 hours ago | not rated yet | 0
For combat veterans suffering from post-traumatic stress disorder, 'fear circuitry' in the brain never rests
Chronic trauma can inflict lasting damage to brain regions associated with fear and anxiety. Previous imaging studies of people with post-traumatic stress disorder, or PTSD, have shown that these brain regions can over-or ...
6 hours ago | not rated yet | 0 |
(Medical Xpress)—What if the quality of your work depends more on your focus on the piano keys or canvas or laptop than your musical or painting or computing skills? If target users can be convinced, they ...
18 hours ago | 3.7 / 5 (3) | 0 |
The neural machinery underlying our olfactory sense continues to be an enigma for neuroscience. A recent review in Neuron seeks to expand traditional ideas about how neurons in the olfactory bulb might encode information about ...
17 hours ago | not rated yet | 0 |
Treatment for alcohol use disorders works best if the patient actively understands and incorporates the interventions provided in the clinic. Multiple factors can influence both the type and degree of neurocognitive abnormalities ...
15 hours ago | not rated yet | 0 |
In order to avoid harms associated with alcohol consumption, in 2009 the National Institute on Alcohol Abuse and Alcoholism issued guidelines that define low-risk drinking. These guidelines differ for men and women: no more ...
15 hours ago | not rated yet | 0 |