Pumping up is easier for people who have been buff before, and now scientists think they know why — muscles retain a memory of their former fitness even as they wither from lack of use. Traditionally, such “muscle memory” has been attributed to neural factors in the absence of any identified local memory mechanism in the muscle tissue.
That memory is stored as DNA-containing nuclei, which proliferate when a muscle is exercised. Contrary to previous thinking, those nuclei aren’t lost when muscles atrophy, researchers reported in the Proceedings of the National Academy of Sciences August 2010. The extra nuclei form a type of muscle memory that allows the muscle to bounce back quickly when retrained.
The findings suggest that exercise early in life could help fend off frailness in the elderly, and also raise questions about how long doping athletes should be banned from competition, says study leader Kristian Gundersen, a physiologist at the University of Oslo in Norway.
Muscle cells are huge, Gundersen says. And because the cells are so big, more than one nucleus is needed to supply the DNA templates for making large amounts of the proteins that give muscle its strength. Previous research has demonstrated that with exercise, muscle cells get even bigger by merging with stem cells called satellite cells, which are nestled between muscle fiber cells. Researchers had previously thought that when muscles atrophy, the extra nuclei are killed by a cell death program called apoptosis.
Memory holding nuclei on muscle fiber light up in green. In the new study, Gundersen’s team simulated the effect of working out by making a muscle that helps lift the toes work harder in mice. As the muscle worked, the number of nuclei increased, starting on day six. Over the course of 21 days, the hard-working muscle increased the number of nuclei in each fiber cell by about 54 percent. Starting on day nine, the muscle cells also started to plump up. Those results indicate that the nuclei come first and muscle mass is added later.
In another set of experiments, the researchers worked the mice’s muscles for two weeks and then severed nerves leading to the muscle so the tissue would atrophy. As the muscle atrophied, the cells deflated to about 40 percent of their bulked-up size, but the number of nuclei in the cells did not change.
These results contradict previous studies that show lots of cell death in muscles during atrophy. Gunderson’s team examined individual cells in the wasting muscles and found that there is apoptosis going on, but that other cells are dying, not the muscle fibers or their extra nuclei. The extra nuclei stick around for at least three months — a long time for a mouse, which lives a couple of years on average, Gundersen says.
“I don’t know if it lasts forever,” he says, “but it seems to be a very long-lasting effect.” Since the extra nuclei don’t die, they could be poised to make muscle proteins again, providing a type of muscle memory, he says.
A review was conducted by The Ottawa Panel recently to update evidence-based clinical practice guideline (EBCPG) on the use of massage compared to a control or other treatments for adults (>18 years) suffering from sub-acute and chronic neck pain.
The panel conducted a literature search from January 1, 1948 to December 31, 2010 for relevant articles. The Ottawa Panel created inclusion criteria focusing on high methodological quality and grading methods. Recommendations were assigned a grade (A, B, C, C+, D, D+, D-) based on strength of evidence.
The results show a total of 45 recommendations from ten articles, including 8 positive recommendations (6 grade A and 2 grade C+) and 23 neutral recommendations (12 grade C and 11 grade D). The authors stated that ” Therapeutic massage can decrease pain, tenderness, and improve range of motion for sub-acute and chronic neck pain.”
The Ottawa Panel concluded that it was able to demonstrate that the massage interventions are effective for relieving immediate post-treatment neck pain symptoms, but data is insufficient for long-term effects.
Clinical implication Massage and myofascial release therapies are able to somewhat attenuate neck pain, but seem to be used more as a complementary treatment due to the immediate post-treatment relief of symptoms. Although the pathological processes responsible for neck pain can often be difficult to identify, identifying and addressing these processes should remain the primary focus of the health care professional. Nevertheless, therapeutic massage can be a valuable tool to temporarily minimize the pain associated with acute neck pain episodes.
The review was published in Journal of Bodywork and Movement Therapies July 2012.
Body massage performance investigation by brain activity analysis
Massage has been widely applied to improve health and reduce stress. However, the performance difference between hands-on treatment and treatment by mechanical devices has been little mentioned. Therefore, the team from Asia University in Taiwan investigated a subject’s EEG performance under massage treatment applied by hand and treatment applied by mechanical devices.
Massage was applied to four acupoints for three minutes each. The massage acupoint sequence was from left Jian-wai-yu, right Jian-wai-yu, left Zuo-fei-yu, and finally right Zuo-fei-yu. An EEG system of 32 channels was used. Twenty-four volunteers, mainly college students, were enrolled. EEG rhythm powers of each massage sessions were derived.
The statistical analysis revealed that there were also significant interactions between the massage stage and the massage type on delta, theta, and beta rhythms , and there were significant differences at different stages for the mechanical massage group The mechanical massage group had more significant differences than the hands-on group for stage coherence of around coherence on alpha rhythm.
The effect of massage on heart rate variability in preterm infants
Researchers from School of Nursing, University of Louisville, USA studied the effect of massage on autonomic nervous system (ANS) function as measured by heart rate variability (HRV) in preterm infants.
Medically stable, 29- to 32-week preterm infants (17 massage, 20 control) were enrolled in a masked, randomized longitudinal study. Licensed massage therapists provided the massage or control condition twice a day for 4 weeks. Weekly HRV, a measure of ANS development and function, was analyzed using statistical analysis.
The results showed that HRV improved in massaged infants but not in the control infants. Massaged males had a greater improvement in HRV than females. HRV in massaged infants was on a trajectory comparable to term-born infants by study completion.
The authors concluded that massage improved HRV in a homogeneous sample of hospitalized, medically stable, preterm male infants and may improve infant response to exogenous stressors. The authors speculated that massage improves ANS function in these infants.
The study was published in Journal of Perinatology
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