| Background:Walking speed is a valid predictor of several chronic diseases and adverse events in the elderly,but there is still a lack of evaluation criteria in clinical application.Osteoporosis is a chronic disease commonly seen in the aging population,and its serious danger lies in the vulnerability to fracture after a fall,which is the second leading cause of nonaccidental injury death in the older adults.Exploring the relationship between walking speed and bone quality may provide new risk factors related to bone health for older adults.On this basis,we will design an aerobic exercise program that monitors exercise intensity by walking speed and is suitable for older adults to participate,verify whether there is an improvement effect on bone quality,and provide a reasonable exercise prescription for people with high risk of osteoporosis.Purpose:This study,including a cross-sectional survey and an intervention experiment,aimed at: 1)assessing the prevalence of walking speed among the healthy old population dwelling in community,of which the data were scarce in China,to know better the current situation and to fill in the data gap;2)analyzing the association of walking speed and bone density among the old,and exploring the potential dose-response effect or the exercising effect over a certain threshold,to provide evidence for clinical application;3)evaluating if the intervention on improving the walking speed would influence or promote bone density among the old.Method:Part 1: In the cross-sectional survey,4,799 healthy,independent living old adults(46.7%males,aged 60 to 79 years)were recruited from communities in six administrative divisions of Shanghai.The walking speed(both normal and the maximum speed)were assessed.The speed trait of the old would be described by living area,sex and age.Part 2: The calcaneus bone stiffness was measured by GE ultrasound device to obtain the stiffness index(SI),the speed of sound(SOS),broadband ultrasound attenuation(BUA),and T-score from two of the six administrative divisions in Part 1.The test was conducted the same time as the survey in Part 1.In addition,the risk factors related to bone density,such as smoking,drinking,fall times,hormone treatment,and vitamins intake,were surveyed,which were included in the model as the adjusting variables.Multiple regression analysis was used to analyze the association between walking speed and calcaneus bone stiffness in the old.Part 3: 100 postmenopausal females were enrolled in the communities of Shang-hai,62 females were included.Participants were assigned to the intervention(weight-lifting and aerobic training)group and the control group according to their willingness.Forty-three females completed the whole program,with eight and eleven dropping out from the intervention and control group after 3-month intervention,respectively.During the intervention,participants in the intervention group had weighted stepping training for 3times per week,60-70 minutes every time,keeping the life routine as before.In the baseline and after-intervention,biochemical variables related to physical fitness,bone density,and were assessed,as well as the survey on height,weight,physical activity level,and medical history of chronic diseases.Result:Part 1: In this cross-sectional study,it was found that the walking speed of the older adults in the community in Shanghai had significant gender differences,height,BMI,age and urban-rural differences.The habitual walking speed of the male was 1.38 ± 0.24 m/s,0.04m/s faster than that of the female.The maximum speed was 1.85 ± 0.27 m/s,which was0.12 m/s faster than that of females.The speed of males in all ages was faster than that of females(p < 0.05).Walking speed of tall older adults(normal :1.39 m/s,maximum:1.85m/s)were faster than the lower group(normal :1.33 m/s,maximum :1.72 m/s.).The walking speed of the older adults with normal BMI(normal :1.38 m/s,maximum :1.80 m/s)was significantly higher than the Overweight(normal:1.35 m/s,maximum: 1.78 m/s)and obesity(normal: 1.32 m/s;maximum 1.73 m/s).The maximum speed of urban population(1.37 m/s)was significantly higher than that of rural population(p < 0.05).Walking speed of the older adults with a history of falling within 1 year(normal: 1.31 m/s;maximum:(1.71 m/s)was significantly lower than those with no fall history(normal: 1.36 m/s;maximum: 1.79 m/s).The walking speed of the Inactive older adults(normal: 1.30 m/s;maximum: 1.72 m/s)was significantly lower than that of active individuals(normal:1.38m/s;maximum: 1.81 m/s).Walking speed of the older adults with cardiovascular risk diseases(normal: 1.34 m/s;maximum: 1.76m/s)significantly lower than that of healthy people(normal: 1.38m/s;maximum: 1.82 m/s).In the subgroup analysis of age group,the habitual walking speed of 60-64 years old group was 1.41 ± 0.23 m/s,and the maximum walking speed was 1.87 m/s.With the increase of age in each 5 years old group,the normal walking speed and maximum walking speed gradually decreased(p < 0.05).The walking speed data of the older adults in different age groups were used to construct the evaluation norm of walking speed of the older adults Part 2: After adjusting confounders,e.g.,body mass index(BMI),total physical activity(TPA),falling times,the walking speed and calcaneus bone stiffness were significantly associated in both male and female old adults.The normal walking speed increased by10cm/s,the calcaneus bone stiffness would increase by 0.92 in males(95%CI = 0.34,1.49),0.93 in females(95%CI = 0.43,1.44).In contrast,the maximum walking speed was up by10cm/s,the calcaneus bone stiffness would be up by 0.57 in males(95%CI = 0.07,1.08),0.66 m/s in females(95%CI = 0.23,1.10).Compared with the lowest quartile men and women in the highest quartile of each walking speed achieved high bone stiffness after adjusting for confounders(p for trend < 0.05).According to the operating characteristic curve(ROC),both normal walking speed and maximum walking speed could be used as diagnostic indicators of low bone mass risk(-2.5< T value ≤-1).The optimal cut-off points of normal walking speed for diagnosing low bone mass risk were 1.46 m/s(male)and 1.31m/s(female).The optimal cut-point of maximum walking speed for the diagnosis of low bone mass risk was 1.74 m/s for men and 1.79 m/s for women.Part 3: Through the aerobic weight-bearing exercise intervention with step speed control,the women with low bone mass in the intervention group increased their customary step speed from 1.28 m/s to 1.39 m/s,and their maximum pace speed increased from 1.72 m/s to 1.93 m/s,all reaching the cut-off point of step speed with normal bone mass.In the weighted and aerobic exercise intervention group,the effect of the time*group interaction on the fastest stride speed and hip extension moment was found to be statistically significant(p < 0.05).Further analysis of the simple effects of group and time revealed that the fastest stride speed at the endline test was significantly higher in the intervention group(1.94 ± 0.19 m/s)than in the control group(1.77 ± 0.16 m/s)(p = 0.002).The maximum walking speed at the post-test in the intervention group increased by 0.15 m/s(95% CI =0.085,0.214)compared to the pre-test(p < 0.001).At baseline testing,the hip extension moment was significantly higher in the intervention group(1.33 ± 0.60 N/kg)than in the control group(0.94 ± 0.50 N/kg)at endline testing(p = 0.016).The hip extension moment increased by 0.56 N/kg(95% CI = 0.304,0.863)at post-test in the intervention group compared to the pre-test(p < 0.001).Results for upper extremity,total body,lumbar L2-4,and femoral trochanter BMD differed by the interaction of group and time.Upper extremity BMD increased by 0.35 g/cm2(95% CI=0.019,0.052)(p < 0.001)and total body BMD increased by 0.016 g/cm2(95% CI=0.01,0.023)(p < 0.001)in the intervention group compared to the pre-test in the upper extremity L2-4 density compared to the pre-test in the lumbar spine L2-4 density increased by 0.03 g/cm2(95% CI=0.019,0.041)(p < 0.001).The control group had a significant decrease in lumbar L2-4 density of 0.015 g/cm2(95%CI=0.004,0.026)(p =0.01)and a decrease in femoral trochanter density of 0.009 g/cm2(95% CI=0.005,0013)(p <0.001)at posttest compared to pretest,and the increase in femoral trochanter density at posttest in the intervention group compared to pretest had a critical effect(p = 0.075).The results for parathyroid hormone and 25 hydroxyvitamin D and femoral trochanteric bone mineral density differed by the interaction of group and time.At endline testing,parathyroid hormone was significantly lower in the intervention group(50.27 ± 13.33 pg/ml)than in the control group(53.38 ± 21.09 pg/ml)(p = 0.01),and parathyroid hormone at posttest in the control group was significantly higher by 7.22 pg/ml(95% CI = 10.291,26.869)compared to baseline(p < 0.001).At endline testing,25 hydroxyvitamin D was significantly higher in the intervention group(47.90 ± 13.92nmol/L)than in the control group(42.06 ± 13.53 nmol/L)(p = 0.022),whereas there was a critical effect of a decrease in 25 hydroxyvitamin D in the control group at pre-and posttest(p = 0.070).Conclusion:The walking speed of community elderly in Shanghai has significant differences among multiple subgroups: male,younger,taller,normal BMI,no history of falls,no cardiovascular risk diseases,and active older people walk faster.The results of this study showed that the walking speed of the older adults aged 60-79 years was positively correlated with calcaneal hardness index(calcaneal hardness index)in both men and women.The faster the walking speed,the higher the calcaneal hardness index,and the walking speed can be used as a diagnostic indicator of low bone mass risk.12 weeks of step-controlled aerobic weight-bearing exercise can significantly improve the walking speed and hip extensor muscle strength in older women.In terms of bone health,exercise intervention can improve the upper limb whole body lumbar L2-4 bone mineral density and 25-hydroxyvitamin D level to some extent in the intervention group. |
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