Experimental Study On Ageing Characteristics Of Muscle Mass And Strength In 55?70 Years Old Women

ObjectiveAging is an irresistible physiological process,resulting in weakness,fractures,decreased immunity,and decreased mobility.Age-related muscle loss is an important manifestation of aging.It is a syndrome that generally declines in muscle mass,muscle strength and activity with age,affecting the daily life of the elderly.The study of muscle loss mostly focuses on the relationship between morbidity,muscle mass or muscle strength and function.There are few studies on the age-related changes of muscle mass and strength and the loss rate of different parts.In this study,we measured the muscle mass and muscle strength of young and middle-aged women,and tried to explain the loss characteristics of muscle mass and strength and the rate of muscle loss in different parts,which provided a theoretical reference for preventing muscle loss in the elderly.MethodsA total of 114 female subjects were enrolled in the study.The subjects were divided into four groups: young group(n=29),56-60 years old group(n=28),61-65 year old group(n=28)and 66.~70 years old group(n=29).Subjects were scanned for whole body muscle content using dual energy X-rays to obtain upper limb,trunk,lower limb and whole body lean mass.The isokinetic muscle strength tester was used to measure the hip and knee joints of the lower limbs and the 60°/S isometric muscle strength,and the maximum average muscle torque and average power of the three joint flexors and extensors at different speeds were obtained.The youth group was used as a standardized lean mass ratio and muscle strength ratio by calculation.Results1.Lean mass resultThere were significant differences in the total lean mass between the left and right sides and the bilateral lower limbs(P<0.01).The loss of lean mass mainly occurred in the lower limbs.The lower limbs and total lean mass of the young group were statistically different from the three groups of middle-aged and older groups(P<0.05),while there were no significant differences between the three groups of middle-aged and older groups.The lean mass was at least 56-60 years old.After the obvious loss.The lean mass ratio showed that the lean mass loss of the lower limbs was significantly more than that of the upper limbs and lower limbs.2.Isometric muscle strength resultHip flexion and extension,knee flexion,and ankle joint extension moment were statistically different between the four groups(P<0.01).Post hoc comparison and muscle strength ratio results showed that hip flexion and extension torque were at least 56-60 years old.After the obvious loss,in the 56-70 age group,the rate of loss occurred after 61-65 years old;the knee flexion moment decreased at least from 61 to 65 years old,and the loss rate accelerated after 61-65 years old;The joint extension torque is obviously lost at least from 56 to 60 years old,and the muscle strength loss is relatively average.3.Isokinetic muscle strength resultHip flexion,knee flexion and extension,ankle flexion and extension moment were statistically different between the four groups(P<0.01);hip flexion and extension,knee and extension,and ankle flexion and extension mean moments existed Statistical difference(P <0.01).After the comparison and muscle strength ratio,it was found that the hip flexion moment was at least significantly lost from 56 to 60 years old.In the 56-70 age group,the loss rate increased after 61 to 65 years old;the knee flexion moment was at least After 61 to 65 years of age,there is a significant decline.The knee extension torque is at least from 56 to 60 years old.The rate of loss between the two is 56-60 to 61-65 years old.Significant loss of ankle flexion and extension moments occurs at least after the age from 56-60 years old,and the rate of loss between the two was faster between 56 and 60 to 61 to 65 years old.Conclusion 1.Loss of muscle mass(1)The loss of muscle mass of the lower limbs occurs earlier than the muscle mass of the trunk and upper limbs.(2)In the age-related changes of lower limb muscle mass,there is an accelerated loss trend after 60 years of age.2.Loss of muscle strength(1)The isometric muscle strength of the ankle joint is lost earlier than the flexion force and the rate of loss is faster.The knee joint extension Isokinetic strength is earlier than the ankle and hip joints.Ankle joint extension and knee extension showed an imbalance in joint muscle strength loss,respectively.(2)The flexion function chain(hip extension,knee flexion and ankle joint extension)is significantly lost in the isometric and isokinetic muscle strength compared with the antagonistic muscle.