The new school year has begun, and physical education class apparently has been replaced by daily weight-lifting sessions via the stuffed-to-bursting backpacks many kids are lugging to and from school every day.

What can parents do to lighten kids’ loads?

First, remember that a child’s pack should weigh no more than 10 percent of the child’s total body weight, says Linda Frasier, an assistant professor of occupational therapy at Touro University Nevada. So, a child who weighs 100 pounds should carry a pack that weighs no more than 10 pounds.

Carrying a pack heavier than that can cause the child pain or discomfort in the back and shoulders, Frasier says. “You could get issues with musculoskeletal formation. Children aren’t fully developed, so this could lead to back problems, curvature of the spine and decreased posture which, over time, leads to other issues and other aches and pains throughout the body.”

When loading a child’s pack, place heavier items in the pack’s center and close to the body, Frasier says. Tighten the straps so that the pack rests close to the body — not hanging below the hips and toward the butt — up near the shoulder blades and above the top of the hip bone.

Encourage the child to always use both shoulder straps, and sternum and hip straps if the pack is equipped with them. All help to secure the pack and make it stable against the body, and the straps will help to distribute the pack’s weight evenly and enhance good posture.

“We also recommend using different compartments to distribute the weight evenly,” Frasier says. “Sometimes they come with side packs, so, maybe, put smaller things to the side.”

Empty the pack each night and repack it for morning, leaving out anything that isn’t needed for the next day’s classes.

“We also think it’s valuable to talk with the child’s teachers to see what books are necessary to bring home that evening, because sometimes we bring too much home that’s not necessary,” Frasier says.

Finally, keep an eye out for signs that your child’s pack is getting the best of him or her.

“If your child starts to complain of pain or numbness either in the neck or arms or hands, or you see red strap marks on the shoulder, or the child’s posture seems to be changing — that hunchback look — these are signs that maybe the backpack is too heavy, and I would weigh the pack on a bathroom scale,” Frasier says.