Research And Application Of Walking Energy Expenditure In Chinese Adults

Background and ObjectivesWalking, as a favorite sport, has been studied for a long time. Although studieshave yielded some good results but there are still many issues that need furtherexploration. Inspired by the improved measurement technology and the high demandsof scientific exercise, we need to take a new perspective to the study of walking.In China, there are few researches about the “Energy expenditure of walking” tillnow so that the evidence for scientific guideline for walking is limited. In that case,the main objectives for this study are as follows: a. measuring the walking features ofChinese population; b. building a prediction equation for walking energy cost; c.evidence-supported walking recommendations; d. discussion about the application ofwalking parameters in the field of exercise intervention.MethodsThere are two sets of methods. The first one is a kind of basic research method.The sample number is1200, aged20-60(male and female; healthy). The test is takenon a flat ground with the speed from4.8km/h to8.8km/h, which is equal to walkingand running respectively. The data is collected by the gas metabolism instrument(Cortex Metamax3B). On the other hand, another group of1200subjects are tested tocollect their step rate from3.8km/h to6.4km/h. The research on utilization of energyfuel is done among some of the subjects: the continuous walking test for a givenspeed, self-selected preferred speed and step-rate test, and changing SF test whilefixing speed.The other kind of methods is applied research methods. Randomized ControlTrial is used in a community.30People (50-60yrs) are divided into three groups tocompare the changes of walking behaviors and health from different interventionstrategies: a control group, a10,000-steps-per-day group, and a fast-SF+3300stepsgroup.Results1. Characteristics of walking energy expenditure and the establishment of predictionformulaWithin the scope of4.8-6.4km/h, the EE increases as long as the speed is increased.When the equation is built, we compared the fitting degrees of three models (Linearmodel, quadratic model, exponential model). The exponential model has the highestdegree.Y1.9e(0.2speed)0.095weight0.0004weight24.52G14.72G0（R2=0.922）. Itindicates that the relationship between speed and energy is not a linear but rather acurvilinear. The curvilinear reflects the extra energy expenditure when lifting walkingspeed and the lower efficiency of energy consumption. Furthermore, there aresignificant differences between the data measured by our study and the estimationfrom the equations built by foreign researchers. And with the accelerated speed, thedifferences increase. It shows the necessity of building our own prediction method forChinese. In this study, we did the back substitution test (relative deviation:±5%).2. Step frequency and walking advice The step frequency (SF) is also an indicator of walking intensity. The SF is moreconvenient for description of the intensity compared with speed. The step ratecut-points corresponding to activity intensity categories (in terms of MET levels) havebeen set up by this study. It could be useful for recommending appropriate amounts ofwalking exercise to meet PA guidelines for Chinese adults. The findings from thisstudy indicate that Chinese adult should walk at least30minutes with a minimal110step·min–1,or3300steps with the same step rate daily to meet PA guidelines. Therewere slight differences on step-rate threshold and minimal steps between women andmen.3. Utilization of energy substrate for walkingThis study investigated the relationship between different speeds, SF, walkingduration, and utilization of energy substrate (oxidation of carbohydrate and fat).It isfound that long time walking with moderate speed is favorable for fat mobilization,while fast walking is positive to CHO mobilization.The self-selected preferred speed is4.0-5.0km/h, with104-120of preferred SF.When changing SF at a given speed, energy consumption of preferred SF is theminimum. Increasing or decreasing SF (±15) not only increases energy consumptioncan also increase the oxidation rate of CHO and fat.4. The results for application researchThis study discussed the use of the walking E.E. parameters in different intervenefields. The parameters can be applied for calculating walking E.E and building theplan for walking exercise though various forms such as the reference, the predictionequation and the table.Moreover, though the walking intervention for8weeks in a community, the partialresults of this study is applied and tested. The results of the intervention show: thewalking goal of3300steps per day can effectively increase the level of physicalactivity (from4500to8800steps per day) for the sedentary seniors, and improvesome heath indicators(decreasing of fat%and DBP). However, the sedentary timewas not deceased. Compared with the traditional program of10,000steps every day,the program is easier to accept for the sedentary people who have no exercise time orexercise habits before, along with good adherence.In addition, pedometer combination of regular consultation activities are aneffective means to increase walking steps during Community walking intervention,which can be promoted in the future.ConclusionsOn the basis of the “Method of Gound Walking Test under Different Speeds” builtin pilot experiments, the E.E parameters are collected from more than1200people ona flat ground. The walking references and equations for estimation are set up on the basis of those parameters, which can help the people make accurate calculation of theenergy cost and develop a walking plan. Besides, the walking advice for Chinese caneffectively increase the level of Physical Activity and improve the health status ofsedentary seniors. In summary, the results of this study provide a valuable referencefor the scientific guidance to the walking for Chinese.