"If you already have an injury, for example, your knee, then running or any other repetitive high impact activity can do further damage to your knee," said Ho.
Endress said that while running might benefit people without an injury history, there are a few things they should keep in mind, such as the need to replace their shoes frequently, and the benefits of nonconcrete surfaces.
He noted that the impact of running on pavement can be problematic, particularly for people who are obese, and said it's probably worthwhile to find softer ground, such as grass, to run on.
However, for healthy people, running should not do any damage.
"If we take a healthy knee and we use proper running habits or running techniques, in a healthy, injury-free person, you can run without causing damage to your joints," said Ho.
Fact or Myth? Exercising Once a Week Isn't Worth It
"Any exercise is better than no exercise," said Ho. "Any exercise, even once a week, will benefit the patient because they will burn off the calories they would not have otherwise burned off."
He said, however, that it won't help people reach their weight loss goals.
"If you're looking specifically, with a goal in mind, to lose weight or to train for an event, for instance training for a marathon or trying to get back into shape, once a week would not be frequent enough to make progress, to reach a specific goal," said Ho.
Endress cautions that once-a-week exercisers, whom he called binge exercisers, are more prone to injury, because they are not used to the strain.
However, he said, one day a week of exercise can still help one get into or maintain a healthy routine.
"For some people, if that's all you can do at this point, that is a good way to at least be consistent with exercise," he said.
Later on, other days of exercise could be added. Also, he said, one day a week might be all someone can manage during the holiday or tax season, but it would make it easier to resume a normal exercise schedule once that period has ended.
"If you can only get in one day, that's at least going to continue the behavior until you can expand out to more days during the week," said Endress.
Fact or Myth? Weight Gain Is Inevitable With Age
Weight gain is not inevitable with age, but is likely because metabolism slows down, and many do not cut their intake of calories.
"If we eat in our 60s the way we were eating in our 20s, of course we're going to gain weight," said Politi.
In addition, most people became less active with age.
"Most people gain weight because they are becoming more sedentary and they keep eating the same as they were when they were young," she said.
The decrease in metabolism is very gradual, however, so Politi notes that being a little more active each year should counter that.
"There's really no reason why you should gain weight as you age, if you become more vigilant."
But simply gaining weight is not a tell-all for poor health, said Ikeda.
"I think it's a myth that you should weigh what you weighted at 21 for the rest of your life," she said. "A 60-year-old does not have the same potential for fitness a 20-year-old has."
She said more research is needed in this area to determine when weight gain becomes a problem, because people will typically gain weight as they get older.
"We don't know how much weight people should gain over a lifetime once they're an adult," said Ikeda.