When it comes to weight-resistance exercise, you can choose free weights such as dumbbells or barbells. Or weight machines, which are often driven by cables or levers. You can use resistance bands or tubes to build strength. Or try pushups and pullups — old standbys that create muscle overload by using your own body weight.

These four basic options for strength training present fitness possibilities for young or old or beginners. And they offer flexibility for use in the gym, your home or in a hotel room during travel.

You’ll probably wind up using a combination of the four, and they all have their pros and cons. They are appropriate for all ages and can be augmented with aerobic exercises like walking or running — or even climbing stairs.

Let’s let Dr. Rafael Escamilla, a biomechanist and physical therapist at Sacramento State University in California, and Dr. Michael Stone, a sports scientist at East Tennessee State University, walk us through the possibilities and their pluses and minuses, depending on your age, your motivation and your goals.

Both are internationally recognized experts, college professors and former competitive weightlifters who still work out almost daily. Both suggest a medical check if you’re just starting out and the guidance of a trainer at the beginning. Most suggest strength training two or three times per week.

Dumbbells and barbells

We’re talking primarily about dumbbells, barbells, kettlebells and medicine balls.

“If you’re relatively healthy, free weights are the way to go,” Stone told The Associated Press. “They have more carryover to daily life — to lifting things. It transfers better. In daily life you pick up your grandchildren, pick up the groceries.”

Free weights are also more versatile, accommodating natural movements that a machine will not allow. Free weights require the user to focus on balance, activating additional muscle groups than simply those targeted.

Stone reminded that you need not use much weight. Just a pound, or a kilo or two, will do it. Start slowly and increase the weight gradually.

“I would also strongly suggest that if you’ve never lifted weights before, go find somebody who knows something about it,” Stone added.

Weight machines

This is probably the least intimidating option for the beginner. The machines offer stability and a fixed pattern of movement and they give beginners a chance to get familiar with the movements involved in strength training.

“Machines are a good way to start,” Escamilla told The Associated Press. “They’re safe and easy and you don’t need a lot of technique or skill to do them.”

Escamilla pointed out they also reduce the risk of injury, isolate muscles and help build confidence as you’re starting out. The machines also are more time effective.

“Start here and then you can gravitate to free weight and other options,” Escamilla said.

Resistance bands and tubes

These are the most portable options. They can help to build muscle, improve flexibility and balance, and avoid the need to sign up for a gym membership. The bands or tubes are made of elastic and come in a variety of sizes and resistance levels — how far they stretch and how difficult it is to stretch them.

Bands also come in fabric models.

“They take up no room to pack and they’re supercheap,” Escamilla said. “You can take them with you as you travel — just throw them in your suitcase.”

You can use them to work your legs, arms, back, chest and shoulders and other muscle groups. They can be used in many configurations and may be less intimidating than dumbbells or barbells.

“The bands won’t cut it for a 300-pound (140-kilo) football player,” Escamilla added. “But they’re good for your average person — your average adult.”

Bodyweight resistance

The idea with every weight-resistance exercise is to overload the muscles. Your own bodyweight can be used to do this.

Exercises like pushups, pullups, squats, lunges and planks and others fall into this category.

“Your body weight can be used as a form of resistance,” Escamilla said. “You can get a good workout doing these and you need almost no equipment.”

No matter the option, Stone emphasized the need to vary your exercises — both the types and the number of repetitions. You can also vary locations, perhaps choosing an outdoor gym for your workouts.

Outdoor gyms are often found on beaches like the one at the popular Barceloneta beach in Barcelona, Spain.

“You can’t do the same number of sets and repetitions all the time and expect to get better results,” Stone said. “You get stale and monotony can set in.”