| Purpose: With increasing age, the fall risk of elderly people would be improved.Many studies used questionnaires of fall risk assessment or activities of daily livingtime on evaluating the fall risk of elderly people, but these methods were in a lowersensitivity. The main causes of falls in elderly people were their neurologicalcognitive ability declined, peripheral system and balance the recession and otherfactors. Choice hand reaction time (CHRT) associated with cognitive function, whilechoice step reaction time (CSRT) not only involved cognitive, but also associatedwith muscle strength. The purpose of this study was using choice hand/step reactiontime and lower extremity muscle power test to investigate why there was a significantdifference between fallers and non-fallers groups during lower limb activity. Weanalyzed the correlation between the muscle power and choice reaction time toevaluate whether choice step reaction time was applicable in predicting the elderlyfalling risk.Methods: A total of140elderly subjects were divided into faller and non-fallergroups based on questionnaire whether they have experienced falls within threemonths of the testing days. They were required to respond to visual stimuli as fast aspossible in four different directions. In addition, their ankle and knee joint averagemuscle power during isokinetic contraction were recorded. After testing for3months,we investigated the relationship between pre-motor time, muscle power, and falls. Atwo-way repeated measure ANOVA was used to test for differences in pre-motor time(PMT) in CSRT and CHRT of the faller and non-faller groups in left and rightdirections. Post-hoc tests with Bonferroni’s correction were used to examine any maineffects or the interaction among the effects. The threshold for significance was set at p<0.05. We compared ankle and knee joint power between fallers and non-fallers byindependent-sample t tests. Pearson correlations were used on the entire participantpool to access the relationship between the PMT and muscle power, as well as toexamine the key factor for fall risk. Through the Receiver operating characteristiccurve (ROC) operating characteristic curve to assess whether PMT in CSRT could bea sensitive index to evaluate the elderly people’s falling risk.Results:1. In CHRT, we found there was no significant difference between fallers andnon-fallers group (p>0.05). There are significant differences when comparing theright and left direction within the fallers and non-fallers groups(p<0.05), the leftdirection reaction is faster than the right side.2. In CSRT, we found there was a significant difference between twogroups(p<0.05), non-fallers group (387.7±47.9ms) was faster than fallers group(456.1±27.9ms). In addition that we found a interaction (group*laerality)(F1,138=10.608, p<0.01), in non-fallers the left limb was faster than the right (373.82±38.34ms,401.62.14±52.44ms, respectively, p<0.01). However, in fallers there was no significant difference between left (453.15±30.21ms) and right(459.00±25.37ms)(p=0.831).3. The fallers also had less average ankle and knee muscle power.4. The area under the receiver operating characteristic curve of PMT in CSRT is0.980, which can identify risk of falling in elderly people.Conclusions:1. We found that elderly people peripheral system recession made their lowerextremity lateralization disappeared, increasing their risk of falls, while the impact ofcognitive decline on fall risk was relatively small by choice reaction test.2. We analyzed the correlation between the muscle power and choice reaction time,found that the elderly people lower extremities muscle power declined was the mainfactor which made their peripheral system recession.3. We found that PMT can be a sensitive index in evaluating risk of falling amongelderly people by receiver operating characteristic curve of PMT in CSRT. |
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