Actor Jin Jae-young, 49, shows off bikini figure — and the workout behind it

Actor Jin Jae-young, 49, drew attention after sharing bikini photos that showed off her toned physique. Known for practicing Pilates consistently, she has sparked renewed interest in how the exercise helps women maintain muscle mass and body shape in their late 40s and beyond.

Jin recently posted several photos on her SNS with the caption: "My photo album is still full of summer. A collection of things I'm reluctant to let go of at the end."

The photos show her relaxing by a pool in a bikini, her lean and toned figure drawing considerable attention from followers.

Jin has shared glimpses of her Pilates practice on SNS on multiple occasions, including advanced moves performed on apparatus — among them poses with her body suspended in the air or hanging upside down.

Pilates involves slow, breath-coordinated movements that engage the muscles stabilizing the torso — the abdomen, back and pelvis. On apparatus such as the reformer and Cadillac, spring resistance allows practitioners to adjust the intensity of each exercise.

From the late 40s onward, maintaining muscle mass and strength matters as much as the number on the scale. As people age, muscle mass and strength tend to decline gradually, and reduced activity can further weaken the glutes, thighs and core.

Pilates engages both the core and the full body because its movements require sustained tension in the abdomen and lower back while the arms and legs are in motion.

A study that put middle-aged women through a 12-week Pilates program found improvements in core strength, lower-body strength, flexibility, agility and balance.

On apparatus Pilates, springs provide resistance or assistance depending on the direction of movement. Unlike free weights, the system lets users fine-tune resistance to match their fitness level without lifting heavy dumbbells or barbells.

Because the method involves relatively few landing or jumping movements, it places less impact on the joints than high-impact exercise such as running — making it a practical option for people returning to exercise after a long break who want to rebuild strength and movement patterns.

Core muscles do more than shape the abdomen. They stabilize the spine and pelvis and keep the body balanced during everyday activities such as walking, lifting and twisting.

When the trunk lacks adequate support, even routine movements can place excess strain on the lower back. Pilates trains trunk stability through exercises that keep the abdominal and back muscles engaged while the limbs move.

Research has also examined Pilates for people with back pain. A systematic review and meta-analysis published in 2024 found that Pilates may help reduce lower back pain and improve function in adults.

Rather than framing any single exercise as a way to fully "correct" poor posture, Pilates is better understood as a method for building the strength to stabilize the spine and pelvis and improving overall body control.

Achieving a toned physique like Jin's requires managing body fat alongside building muscle. Pilates burns energy as a physical activity, and practiced consistently it supports strength and fitness — though calories expended vary with intensity and duration.

For those whose primary goal is reducing body fat, pairing Pilates with aerobic exercise — brisk walking, running, swimming or cycling — is advisable. On the dietary side, rather than severe caloric restriction, consuming adequate protein, vegetables and carbohydrates while moderating overall energy intake is the better approach.

In middle age particularly, drastically cutting food intake to lose weight can cause muscle loss alongside fat loss. Combining strength training with sufficient protein intake helps preserve muscle during the weight-loss process.

Women in their late 40s and beyond also need to pay attention to bone health alongside muscle. Hormonal changes around menopause can accelerate bone density loss.

While Pilates can improve balance, strength and physical function, its effect on bone density has not been clearly established. A meta-analysis of studies on postmenopausal women found no significant evidence that Pilates raises bone mineral density in the lumbar spine, hip joint or femoral neck.

For those who want to address bone health as well, combining Pilates with weight-bearing activities such as walking or stair climbing — along with resistance exercises like squats and lunges — is the recommended approach.

The advanced moves Jin has shared — suspending the body on apparatus or hanging upside down — are not necessary to gain the benefits of Pilates. Beginners are better served by mastering the fundamentals first.

Starting out, the priority should be performing basic movements accurately while maintaining proper breathing, pelvic positioning and spinal alignment. Advancing too quickly without a solid foundation can place undue strain on the lower back, neck and shoulders.

Heavier spring resistance does not automatically mean a more effective workout. Depending on the movement, a stronger spring can actually assist the motion, while a lighter spring forces the body to support itself and raises the difficulty. Matching the spring setting to one's strength and skill level is what matters.

People with osteoporosis, spinal conditions or a recent surgical history need to modify the type and range of exercises they attempt. Those with significantly low bone density or a history of vertebral compression fractures should be particularly careful with movements involving deep spinal flexion or rotation, adjusting them to suit their individual condition.

The real benefit of Pilates lies not in impressive advanced poses but in the repeated practice of controlling the body. A long-term habit of consistent exercise, as Jin demonstrates, can help maintain core strength, muscle mass and balance well into middle age and beyond. Adding aerobic and resistance training to the mix allows practitioners to manage not just body shape but muscle and bone health as well.