It's well know that exercise can be an antidote to depression. This is particularly relevant to people living in Northern regions with very short periods of daylight. How much exercise do you need to avoid feeling gloomy? Not much, it turns out. According to a study published in this month’s British Journal of Sports Medicine: a mere 20 minutes a week of any physical activity, whether sports, walking, gardening or even housecleaning, will do it... Exactly how much physical activity is required to obtain its health benefits? A review of dozens of studies on the health effects of exercise did:
ultimately reach some conclusions about how much — or, really, how little — exercise we each should be doing. That minimum amount of exercise required to see a significant lowering of your risk of dying prematurely was, they concluded, 500 MET minutes of exercise a week... A single MET, or Metabolic Equivalent of Task, is the amount of energy a person uses at rest. Two METs represent twice the energy burned at rest; four METs, four times the energy used at rest; and so on. Walking at three miles per hour is a 3.3-MET activity, while running at 6 miles an hour is a 10-MET activity. The committee concluded that a person needs to accumulate a weekly minimum of 500 MET minutes of exercise, which does not mean 500 minutes of exercise. Instead, 150 minutes a week (two and a half hours) of a moderate, three- to five-MET activity, such as walking, works out to be about 500 MET minutes. Half as much time (an hour and 15 minutes per week) spent on a 6-plus MET activity like easy jogging seems, according to the committee, to have similar health effects.Of particular interest to a worrywart like myself who is extremely physically fit, but concerned about the normal loss of muscle mass that occurs in my age group (65-75) over the next ten years, a recent study suggests that visiting the gym only once a week is sufficient to hold on to muscle mass and previous strength gains.
Interestingly, they did not find that exercise beyond a certain point conferred significant additional health benefits. Instead, the “dose response” for exercise, the committee found, is “curvilinear.” In other words, people who are the least active to start with get the most health benefit from starting to exercise. People who already are fit don’t necessarily get a big additional health benefit from adding more workout time to their regimens.
It has now been shown that weight resistance training, as well as aerobic exercise, boosts levels of the brain growth factor BNDF and cognitive enhancement (in rats, that is, and most likely us too.)
A further curious counterintuitive note: Exercising increases the urge to drink alcohol, and drinkers are more likely to exercise more.