Frequent and regular exercise has been shown to help prevent or to cure major illnesses such as high blood pressure, obesity, heart disease, Type 2 diabetes, insomnia, cancer and depression, and many more diseases. However, the actual risk reduction may not be as large as one expects. Researchers have shown that three 10 minute walks burn as many calories and exercise your heart as well as one 30 minute walk. Exercise can also increase energy and raise your threshold for pain. There is conflicting evidence as to whether vigorous exercise (more than 70% of VO2 max) is more or less beneficial than moderate exercise (40 to 70% of VO2 max).
However studies have shown that vigorous exercise executed by healthy individuals can effectively increase opioid peptides (aka endorphins, a naturally occurring opiate that in conjunction with other neurotransmitters is responsible for exercise induced euphoria and has been shown to be addictive), positively influence hormone production (i.e., increase testosterone and growth hormone), and help prevent neuromuscular diseases.
Some of these benefits can be realized by moderate exercise but to a much lesser degree. Disadvantages of exercise
Too much exercise can be harmful. The body needs sufficient rest, which is why most health experts say one should exercise every other day or 3 times a week. Without proper rest, the chance of stroke or other circulation problems increases, and muscle tissue may develop slowly. Over-exercising does more harm than good. For many activities, especially running, there are also significant injuries that occur with poorly regimented exercise schedules. In extreme instances, over-exercising induces serious performance loss. Unaccustomed overexertion of muscles leads to rhabdomyolysis (damage to muscle) most often seen in new army recruits. Stopping excessive exercise suddenly can also create a change in mood. Feelings of depression and agitation can occur when withdrawal from the natural endorphins produced by exercise occurs.
Physical exercise releases opioid peptides or endorphins, opiates that exhibit synergetic effects with other neurotransmitters, causing exercise euphoria, also known as “runners high”, and causing addiction to physical exercise and possibly decreased sex drive. This usually leads to over-exercising and those suffering exercise addiction are often described as “gym rat”, “gym addict”, “exercise freak”, etc. Excess is unhealthy. Exercise should be controlled by each body’s inherent limitations. While one set of joints and muscles may have the tolerance to withstand multiple marathons, another body may be damaged by 20 minutes of light jogging. This must be determined by each exerciser.