To Your Health: How does skipping workouts affect your fitness?

Even the most motivated among us is bound to miss a workout or two — or maybe 31 in a row. But how much of a difference can a few missed workouts really make?

If you've been keeping up your exercise regimen, your body probably welcomes a couple of days off. It'll use the time to repair your muscles and help you spring back stronger.

When you haven't worked out in a week, your muscle fibers start to dwindle and your body retains some extra fluids. Nonetheless, if you head back to the gym now, you probably won't notice any significant changes in your workout level.

When you haven't worked out in a couple of weeks, your fitness goes on the downhill slide. Your cardio endurance will be the first thing to go. Taking the stairs might make your legs burn or even leave you sucking wind.

When you haven't worked out in a month, most of your cardio and strength gains from earlier workouts have gone kaput. You're sporting less lean muscle mass and more body fat.

When you haven't worked out in a few months, your metabolism joins the ranks of things to go. Your heart has to work harder with every beat, and your lungs don't absorb as much oxygen as they used to.

And when you haven't worked out in a year? Aside from a soaring body-fat percentage, complete loss of muscle and sluggish metabolism, you're also at a greater risk of serious health issues such as high blood pressure, high cholesterol, type 2 diabetes, insomnia and depression.

A study recommends giving vitamin D supplements to children who are still breast-feeding after their first birthday.

"This is important for exclusively breast-fed infants and dark-skinned children, who are at particular risk of nutritional rickets," said Mayo Clinic family medicine physician Dr. Tom Thacher, who was not involved in the study.

The American Academy of Pediatrics recommends vitamin D supplementation of breast-fed infants to prevent rickets, a softening and weakening of bones in children.

A deficiency of vitamin D makes it difficult to maintain proper calcium and phosphorus levels in bones, which can cause rickets. Children 3 to 36 months old are most at risk for this because their skeletons are growing so rapidly.

Researchers in the study found children who were breast-fed up to 36 months and did not take supplements were more likely to develop vitamin D deficiency even though they had started eating solid foods.