Impact of Melatonin on Skeletal Muscle and Exercise – free full-text /PMC7072499/ – Cells. Feb 2020
Skeletal muscle disorders are dramatically increasing with human aging with enormous sanitary costs and impact on the quality of life.
Melatonin, the indole produced at nighttime in pineal and extra-pineal sites in mammalians, has recognized anti-aging, anti-inflammatory, and anti-oxidant properties.
Mitochondria are the favorite target of melatonin, which maintains them efficiently, scavenging free radicals and reducing oxidative damage. Here, we discuss the most recent evidence of dietary melatonin efficacy in age-related skeletal muscle disorders in cellular, preclinical, and clinical studies.
Furthermore, we analyze the emerging impact of melatonin on physical activity.
Finally, we consider the newest evidence of the gut–muscle axis and the influence of exercise and probably melatonin on the microbiota
In our opinion, this review reinforces the relevance of melatonin as a safe nutraceutical that limits skeletal muscle frailty and prolongs physical performance.
Melatonin Alleviates Skeletal Muscle Disorders In Vitro and In Vivo
Melatonin (N-acetyl-5-methoxytryptamine) is an evolutionary-conserved molecule originally isolated from the pineal gland and considered a regulator of circadian rhythms and seasonal breeding.
Actually, melatonin has multiple extraordinary functions such as anti-tumor, antioxidant, and anti-inflammatory indolamine.
Since it’s known to be so very useful I’m puzzled it isn’t used more in current medical practice.
The compelling evidence of decreased endogenous melatonin in senescence triggered intense research on its potential role as a dietary supplement to prevent and treat aging and age-related diseases
Intriguingly, in postmenopausal women, the drop of urinary melatonin correlated with sarcopenia.
“Sarcopenia is a syndrome characterized by progressive and generalized loss of skeletal muscle mass and strength and it is strictly correlated with physical disability, poor quality of life, and death.”
Chronic melatonin intake prevented age-related mitochondrial damage in the heart and the diaphragm muscle of accelerated aged SAMP 8-mice.
Interestingly, exogenous melatonin
- regulated insulin resistance,
- ameliorated mitochondrial function in rat muscles, and
- prevented chemically induced apoptosis and endoplasmic reticulum stress in different skeletal muscle cells in vitro.
I had delved into the function of the “endoplasmic reticulum” in 2015, led there by my research on collagen and connective tissue. It’s an important topic for chronic pain because Endoplasmic Reticulum Stress is Pain Regulator.
Chronic muscular pain, cognitive dysfunctions, and sleep disorders are all hallmarks of fibromyalgia linked to reduced urinary secretion of melatonin in women.
…our group studied the effects of melatonin in fibromyalgia in rats….data strongly indicated that, in the muscle, melatonin directly accumulated in the mitochondria where it was able to sustain proper size and function.
Exercise—an Anti-Aging Strategy that Preserves Mitochondria in Skeletal Muscle
there are different types of physical training with different impact on skeletal muscle composition and metabolism:
- chronic, or
- glycolytic and aerobic exercise.
Different types of exercise can be combined in a mixed training.
Exercise greatly remodels skeletal muscle mitochondria size and number and accelerates mitophagy, the peculiar dismantling of damaged mitochondria.
I’ve previously posted about mitochondria in these posts.
Indeed, the proper balance between new synthesis of mitochondria and mitochondrial degradation is dramatically altered in aged skeletal muscles.
Day/night cycles and seasonal rhythms are evolutionary-conserved activities that deeply influence skeletal muscle mass, performance, and mitochondrial function.
The circadian clock conditions whole body homeostasis and mainly the sleep–wake cycles that are essential for mental and physical fitness.
Exercise is another essential nonphotic Zeitgeber [German: time-giver] that synchronizes the circadian pathway and sleep depth and controls muscle physiology during all lifespans but greatly in aging.
Accumulating evidence in rodents indicates that endogenous melatonin and circadian systems are modulated by repeated vigorous exercise able to maintain the synchronous phase.
Melatonin intake before and during exercise reduces glucose resistance and ameliorates antioxidant status in various situations, such as during preparatory training, in a soccer training camp, in resistance, or in high-trained athletes.
Remarkably, in humans, melatonin was devoid of any side effect despite administration via several routes.
This is extremely important. Few supplements can claim to be so benign, so it certainly gives me the courage to experiment with it.
Currently, melatonin is not still administered at the best “clinical” dosage, from 40 to 100 mg/day, that is necessary to obtain the best results in metabolic and neurodegenerative diseases.