A newly identified muscle protein may help explain why people who stay active as they age often remain stronger and healthier for longer , according to new research. Scientists found that a protein called NOX4 naturally declines with age and inactivity. As levels dropped, researchers observed signs of frailty, muscle loss, insulin resistance and liver disease in mice. The findings were published in the journal Science Advances. 7 COMMON FITNESS MISTAKES OLDER ADULTS MAKE AND HOW TO AVOID THEM FOR BETTER WORKOUTS Researchers believe NOX4 helps muscles repair themselves and adapt to the physical demands of exercise. When NOX4 was removed from the muscles of mice, the animals became weaker, lost muscle mass and developed health problems commonly associated with aging. The researchers also found that exercise helped restore NOX4 levels in older mice. Josephine Hunt, an educational leader, former group fitness instructor and founder of The Resilience Revolution based in New Jersey, who was...