中老年人以DXA測量肌力與肌肉量相關性之探討

Correlation Between Muscle Strength and Muscle Mass Measured by DXA in Middle-aged and Older People

目的：有良好的肌肉力量得以降低跌倒風險，並保持中老年人的生活品質，過去文獻中對於中老年人下肢肌肉量和下肢肌力的探討較少，本研究利用雙能量X光骨質密度吸收測量儀(dual-energy X-ray absorptiometry, DXA)來分析中老年人下肢肌肉量與下肢肌力之相關性。方法：針對臺灣地區72位50歲以上的中老年人，分別用DXA和等速肌力系統測量下肢肌肉量和肌力，所得資料進行男性與女性的差異性分析，以及下肢肌肉量與下肢肌力相關性分析。結果：本研究共納入男性31位與女性41位中老年人進行分析，平均年齡60.71±6.24歲，分析結果如下：男性下肢肌肉量較女性高，女性下肢脂肪量較男性高，且男性下肢肌肉量與肌力顯著高於女性(P<0.001)，而下肢肌肉量與肌力呈現顯著正相關(左腿：r=0.65，p<0.01；右腿：r=0.71，p<0.01)。結論：研究顯示DXA測量的下肢肌肉量與下肢肌力有顯著相關，而下肢肌肉量為中老年人跌倒的重要因子，因此，未來可進一步探討利用DXA的測量來協助中老年人跌倒關係之評估。

Objectives. Middle-aged and older people with adequate muscle strength have been found to be at lower risk of falls and able to maintain good life quality. However, there is little reported research focusing on lower-limb muscle mass and muscle strength in this population. In this research, we studied the relationship between lower-limb muscle mass and muscle strength in middle-aged and older people by Dual-energy X-ray Absorptiometry (DXA).
Methods. We analyzed DXA and isokinetic data collected from selected 72 subjects over 50 years old. We compared differences between males and females and studied the association between lower-limb muscle mass and muscle strength in our subjects.
Results. In total, this study enrolled 31 males and 41 females with a median age of 60.71±6.24 years. Males were found to have more muscle mass, while females more adipose mass. The association between lower-limb muscle mass and muscle strength performance in males was higher than it was among female’s (p<0.001). We also found a high positive correlation between lower limb muscle mass and muscle strength (Left leg: r=0.65, p<0.01; Right leg: r=0.71, p<0.01).
Conclusion. This study found a high positive correlation between lower-limb muscle mass and muscle strength among our older subjects. Thus, lower-limb muscle mass could possibly be an important factor when considering risk of falls. Future studies might want to study the association between DXA and fall risk among older people.