When we asked readers what they want to know about exercise and the coronavirus, many of you wrote that you were concerned about how to exercise and maintain fitness if you or someone you love is older or has functional limitations, such as arthritis or joint replacements. Experts who study exercise and aging had a lot to say.

Among their suggestions: Soup-can dumbbells and indoor gardening might help older people who are new to working out to weather the physical effects of a prolonged coronavirus lockdown. Access to a stairwell also is a boon, they say, but even a hallway can be a route to sustained fitness.

Dr. Aronson and other exercise scientists offered a variety of recommendations about the types and amounts of activities older people might try to complete in their buildings, homes, living rooms or even chairs during the lockdowns to stave off frailty and maintain their health. The expert responses proved to be uniformly reassuring, boiling down to the advice that all of us, regardless of age, move whenever and however we can, using whatever equipment we already have at hand.

More specifically, the experts suggest starting with a focus on aerobic conditioning, which, in practical terms, means walking, if at all possible, but not necessarily formal walks. Instead, Dr. Aronson says, try to build movement into ostensibly sedentary parts of your day.

“During a phone call,” she says, “walk around the room or up and down a hallway” (assuming you are not using a landline). When you watch television, get up during each commercial break and stroll from room to room. Or if you have access to a stairwell, she says, climb a flight or two of steps, which provides a brief but effective aerobic workout and some leg strengthening. Wear a mask and gloves if the stairs are public, of course, and hold tight to the banister.

Ideally, older people should aim to stroll from room to room or up and down a corridor at least three times a day, Dr. Aronson says. “It may be only two or three minutes of activity at a time, but it all counts and adds up.”

Look, too, for opportunities for simple, low-tech muscle workouts, the experts all say. Even skimpy, intermittent resistance training can help people avoid shedding muscle mass and strength during this lockdown.

Consider the wall squat, for instance, says Dr. James Gladstone, the chief of sports medicine at Mount Sinai Health Center in New York City. This exercise requires little expertise or equipment, apart from a wall, but robustly improves leg strength. Simply stand upright a foot or so from a wall, legs shoulder distance apart. Press your back against the wall and slide down until your thighs are almost parallel with the ground. (Stop earlier if your knees hurt.) Hold this simulated sit as long as you can. “If that means five seconds, fine,” Dr. Gladstone says. Slide back up the wall, rest a few seconds, and slide down to sit again.

For upper-body strengthening, raid the pantry, suggests Jennifer Copeland, a professor and director of the Active Healthy Aging lab at the University of Lethbridge in Alberta, Canada. Cans of soup or fluid-filled water bottles provide sufficient resistance for arm curls, she says. Grip those objects with your arms by your side, palms forward, and slowly bend your elbows to curl the can or bottle upward. Lower and repeat.

To strengthen shoulders, she says, partially fill an empty gallon milk jug with water, hold it with both hands in front of you, arms straight, and slowly raise it to about face height. Lower gently and repeat. You can do this exercise seated.

Similarly, to improve overall arm strength, re-seat yourself a few times, she says. In other words, when you start to get up from a chair, purposely sit back down and partially rise several additional times, using your arms for support and leverage.

Even ordering seeds and starting an indoor herb garden, undemanding as that activity might seem, can “get people out of their chairs and standing and moving,” Dr. Copeland says. “Anything like that is good.”

Finally, if you prefer group activities or exercise variety, the internet is overflowing now with free exercise classes and instructional videos, Dr. Aronson says, many of them oriented toward older or inexperienced exercisers. Try a dance video if you feel vigorous and coordinated, she says, or tai chi for something gentler. Or Zoom a yoga class with friends, to stretch and reach together across the miles.

YouTube offers a variety of free home exercise programs: