It is no secret that exercise is an absolute necessity for us all, exercise is medicine. Fortunately, it is also cheaper than medicine. Different types of exercises result in different beneficial outcomes for our bodies. Endurance exercise can improve cognition and also protect the brain from degeneration by elevating a molecule called irisin, for example. Unfortunately, there are also some studies that suggest that our bodies may have a limit, at which point undesirable consequences result. So, at what point is too much of a good thing, too much?
IRISIN- Neuroprotective Effects Induced By Exercise
Cellular biologists at Dana-Farber Cancer Institute at Harvard Medical School reported their groundbreaking discovery of irisin, named after the Greek mythological goddess Iris (the messenger of the gods). Irisin, a byproduct of the hormone FNDC5 (Fibronectin type III domain-containing protein 5) is exercise-induced and believed to have neuroprotective effects.
The effects of exercise on the brain are most apparent in the hippocampus, a part of the brain involved in learning and memory. In a review article published in Brain Plasticity in 2015, researchers found that if they artificially increased the levels of irisin in the blood, it resulted in an increased activation of the genes responsible for learning and memory. The team also found that raising levels of irisin in the circulation caused the molecule to cross the blood brain barrier, which additionally increased the expression of BDNF (brain-derived neurotrophic factor) and activated genes involved in cognition among other neuroprotective genes. A win-win scenario.
Exercise is medicine. Experiments have shown that irisin levels increase as a result of regular aerobic exercise, but not during short-term, high-intensity bursts of anaerobic muscle activity such as HIIT (High Intensity Interval Training). In a study using participants of Ironman (140.6 miles) and Half Ironman (70.3 miles) competitions, the levels of irisin were elevated in the Ironman and Half Ironman competitors but the increase was insignificant in a similar study done on Ultramarathoners … suggesting that long endurance is good, but not too long?
How much is too much?
Overtraining can be stressful for the body. Negative side effects of such stressors can affect blood levels of important neurotransmitters which can lead to chronic fatigue or even thyroid disorders. In response to stress, the body secretes a hormone called cortisol. If levels stay high for too long, cortisol has been shown to damage and kill cells in the hippocampus and possibly cause premature brain aging. Professor Joe Herbert at the neuroscience department of the University of Cambridge states that we cannot live without cortisol but too much of it can make your brain vulnerable to problems like stroke and ageing.
In the Journal of the American College of Cardiology, a study was conducted on the amount of exercise people should do. Researcher Jacob Marott, at the Copenhagen City Heart Study at Frederiksberg Hospital was surprised at the results. He and colleagues found that athletes, such as marathoners, who ran more than 4 hours per week were at just as much of a risk of dying early from heart complications as someone who lived a sedentary life on the couch. They recommend running from one to 2.4 hours per week, at a slow to moderate pace.
Though scientists have not reached a unanimous decision regarding exactly how much exercise is the perfect amount, it’s probably safe to say that it differs per person and to exercise often while perhaps mixing up your routine regularly from time to time.
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