Healthy Walking in your Lunch Hour – Optimising healthy walkingactivity over 30 minutes Sukin ReddyIndukuriMBBS, MS Ortho Thesissubmitted in part fulfilment of theMCh OrthopaedicsDegreeUniversity of DundeeApril ~ 2018CHAPTER 1 1.1 IntroductionMaintaining an active lifestyle has become challengingthese days. Work demands in particular are getting in the way of exercising.
While we struggle to find time to exercise, we cannot afford to forsakeexercise because it is integral to sustained healthy success and a well-roundedlife. Physical inactivity is now estimated to be one of the leading causes ofdeath worldwide (World Health Organization, 2010). Prolonged sedentary behaviour can have dangeroushealth consequences, including increased risk of diabetes, cardiovasculardisease and premature mortality (Hill et al, 2015).There is emerging evidence IC1 tosuggest that participation in light intensity physical activities (e.
g.standing or slow walking) may have benefits for cardio-metabolic health (Hill et al, 2015).Active travel (walking, cycling and public transportuse) is being promoted as an important component of strategies to increasephysical activity levels internationally (World Health Organization, 2013).Walking is considered as one of the safest, simplestand most efficient forms of cardiovascular exercise and can be performed almostanywhere. It is as effective as other forms of cardiovascular exercise and doesnot require expensive equipment or regular visits to a gym (Siegel et al, 1995). Walking is a greatexercise for all ages and in somecases, it can be more effective thanrunning however a good walking technique is very important to maximise theresults. Walking, as opposed to running, is anexceptionally safe activity, since it involves having one leg always in contactwith the ground, which minimizes the risk of falls and injuries (Perry and Burnfield, 2010), (Hardman and Morris, 1998).In 2006, the World Health Organization (WHO) concludedthat walking is the basic form of physical activity necessary for maintaininggood health and should be an inseparable part of a healthy everyday lifestyle,including working days (World Health Organization, 2006).
The recommended amount of exercise for adults is 150 minutes of moderatephysical activity per week. That breaks down to 30 minutes of exercise overfive days a week (World Health Organization, 2010).The American Heart AssociationRecommended the same in 2015 and updated them in 2017 (American Heart Association, 2017).Although many techniques have been proposed to increasethe efficiency of walking over shorter duration of exercise such as the use ofweights, brisk walking, uphill walking and so on, there is no significantemphasis on shortening of stride length to improve the intensity ofcardiovascular exercise. Shorter strides while walking increase the step countand may increase cardiovascular exercise over a 30-minute period compared tonormal/regular strides.
There is not a similar study in the available literaturewhich has evaluated the effects of shorter strides during walking oncardiovascular exercise. Hence, the reason for conducting this current study incomparing the outcome.The study included 50 subjects who normally walk forthirty minutes or more each day. They will be subjected to a single 90-minutesession comprising two 30-minute walking and one 30-minute rest phase inbetween where data will be collected. There will be no follow up and the datawill be analysed after the sample size has been reached.Previous studies have indicated that slower walkingspeed in elderly subjects may be associated with decreased joint movements andjoint kinetics (Kerrigan et al, 2000), (Kerrigan et al, 2001) biomechanical changes (DeVita and Hortobagyi, 2000),and in choosing “cautious” gait strategy (Winter et al, 1990). Treadmill walking, in theory, is mechanicallyequivalent to over ground walking (Savelberg et al, 1998), (Schenau, 1980). In reality,however, walking on a treadmill can initially be an unfamiliar experience (Schenau, 1980), (Taylor et al, 1996)Unimpaired younger adults required 4–6?min tofamiliarize themselves with the treadmill (Taylor et al, 1996), (Matsas et al, 2000).
However, completefamiliarization with a treadmill even in a 15-min single session was notattained in many elderly adults (Wass et al, 2005).Therefore, in this current study the normal walkingspeed on the treadmill will be defined according to preference of individualparticipants. 1.
2 Aims & objectivesObjectives:To determine whether the use of a stride restrictorwhile walking alters cardio vascular exercise.To study the effect of stride changes on heart rateand maximal oxygen consumption.Aim:To determine whether a change in stride length can altercardiovascular exercise over a 30-minute period. CHAPTER 2 LiteraturereviewOf all types of physical activity, walking stands outas the most popular form of leisure time exercise (Ham et al, 2009), and can be easily performedat moderate intensity (Murtagh et al, 2002).
Various studies have been conducted to understand thebenefits of walking as a cardiovascular exercise. Although it has been provedto be safer and as effective as any other form cardiovascular exercise. Manyresearch projects have proposed ways of maximising the efficiency of walking toachieve the same results with a shorter duration of exercise. 2.1 Physical activity and aerobic fitnessNoakes IC2 et al. (2009), found that cardio respiratory fitness is more a function of theintensity of physical activity than its volume in middle-aged women in a studyof 275 women (40.
1+/-3.0 years) (Noakes, 2009).Aadlandet al.
(2013), identified that an increased physical activity level overa one year period resulted in increased aerobic fitness in severely obesesubjects. Although the sample size was small (21 subjects, mean age 42), theseresults suggest that change in 6-minute walking test may not be a goodindicator of maximal change in aerobic fitness in this population (Adland et al, 2013).Laudani et al. (2013), conducted a study that included72 volunteers and concluded that there is a significant association between physicalactivity levels and physiological determinants of mobility in young,middle-aged and older individuals living in a city district, with significantdifferences in the relative role played by volume and intensity of overall physicalactivity and selected habitual activities. While aerobic function wasassociated to the volume of activity, neuromuscular function and functionalabilities showed a significant association exclusively with the intensity ofphysical activity (Ludini et al, 2013).2.2 Physical activity and DisabilityNusselder et al.
(2008), identified that performing moderateto high levels of non-occupational physical activity reduced incidence, andshowed a higher gain in disability-free years (male 4.1; female 4.7), also asimilar reduction in years with disability (Nusselder et al, 2008).
2.3 Physical activity and workNaughton et al. (2010), conducted a survey in 2010 inwhich 44 employees from a health provider (Health) and 63 employees from apublic-sector organisation (PSO) underwent a self-completed questionnaireenquiring about a broad range of workplace-based exercise issues and identifiedthat overall, employees from Health and PSO were positive about the policies atwork to encourage exercise but further work was required toensure that public health guidance was aimed at improving exercise at work sothat it has maximal worker benefit (Naughton et al, 2010).McKay et al. (2015), conducted a cross sectional studyof 2,122 adults aged 18 years and above in rural India and Bangladesh and foundthat those that achieved the recommended weekly physical activity levelsthrough work-based activity were more likely to achieve it. The only problem inthis study according to the author was physical activity data were based onself-reporting similar to the International Physical Activity Questionnaire(IPAQ), which has been associated with overestimation of physical activitylevels (McKay et al, 2015).
2.4 Effect of environmrntHandy et al. (2002), published an evidence based studythat was aimed at understanding the interrelationship between the builtenvironment and human behaviour and then to develop models that predicted theenvironmental conditions under which humans will be more physically active.The study identified that walking and cycling have beenmore popular and successful modes of exercise than other forms of travel becausethey are relatively easy for the vast majority of the population and offerrelatively little risk of injury.It was concluded that that a combination of urbandesign, land use patterns, and transportation systems that promote walking and cyclingwill help create active, healthier, and more liveable IC3 communities (Handy et al, 2002).Brownson et al.(2005), identified thatit was difficult to precisely quantify IC4 owing to the lack of long-term data, acombination of characteristics of the built environment and increases in theproportion of the population engaging in sedentary activities that put themajority of the American population at high risk of physical inactivity.
The studyconcluded that a complex interaction of cultural, social, economic, andfamilial issues has likely set the stage for these changing physical activitytrends (Brownson et al, 2005).2.5 Active travelMytton et al. (2017), conducted a study involving 7689working men in the UK to understand the associations of active commuting withbody fat and visceral adipose tissue and identified that walking and cycling towork was associated with reduced adiposity relative to exclusive car-use (Mytton et al, 2017).2.
6 Walking TrainingKocur et al. (2012), conducted an evidence based studyand recommended parameters of walking training which can be applied to primaryand secondary cardiac prevention (Kocur et al, 2012).Table 2.1: Kocur et al, parameters ofwalking training which can be applied to primary and secondary cardiacprevention Atalay & Cavlak (2012), studied the impact ofunsupervised regular walking on health in a sample of 40 Turkish middle-agedand older adults with a mean age of 56.30 ± 4.
85 years (range 40–70) walkingfor at least 1 year, at least three times a week, and at least 45 min a day and40 inactive participants with a mean age of 55.15 ± 5.64 years (range 40–70) andconcluded that unsupervised regular walking improves health and is also a safe,cheap, and can easily be adapted into daily life.
Therefore, it can berecommended to improve physical and cognitive functioning, emotional status,and quality of life of middle-aged and older adults (Atalay and Cavlak, 2012).Rosa et al. (2015), conducted a study involving 94volunteers aged 18+ and found that differences in prior expectations that motivatepeople to participate in a training program can augment or reduce the chancesof completing the exercise protocol as 73volunteers (77.
6% of the entire sample – 40 women) did not complete theprotocol, and 21 volunteers (13 women) completed the full 1-year exercise protocol.The expectation of social interaction was a positivefactor in predicting maintenance of an exercise program and suggested thatstructuring physical exercise sessions would facilitate socialization and mayincrease adherence (Rosa et al, 2018).2.7 Duration of walkHarvey et al. (2017), observed in 10 healthy volunteersthat 30?minutes of moderate intensity physical activity can be accumulated incontinuous bouts of at least 10?minutes but it was shown by use of activity monitoringthat it was difficult to achieve 10?minutes of completely uninterrupted walkingin the free-living urban environment where there are obstacles. Oxygen uptake (VO2)was measured using a gas analysis system.The study concluded that 10?second interruptions inwalking had no significant effect on the VO2 kg min?1.However, two breaks of 50?seconds or 100?seconds introduced into a 5-minutebrisk walk showed a significant reduction in oxygen uptake requirements andmetabolic equivalent of task (MET) (p?0.
001) compared to continuouswalking for the same amount of effective walking (Harvey et al, 2017).2.8 speed of walkMurtagh et al. (2002), observed in 82 subjects agedbetween 21 and 74 years (28 men, 54 women) that instructing individuals to”walk briskly” (speed 1.86 ± 0.12 m · s?1)prompts more vigorous physical activity (Murtagh et al, 2002).
Chungand Wang (2009), studied 30 healthy male and female subjects aged between 20-80and observed that the preferred walkingspeed (PWS) decreased with the increase of age for both genders (Chung et al, 2010). Takuji et al. (2017), conducted a study on 350 subjects(elderly women aged 75 years or over) and found that moderate to vigorousphysical activity was negatively associated with slow walking speed,independent from step counts and confounders (Takuji et al, 2018).2.9 distance of walkSugiura (2002) conducted a study involving 48menopausal women (age: 40–60 years) and observed that daily exercise as well asincreasing the number of daily steps as a moderate exercise can improve theprofile of serum lipids in menopausal women. However, it is difficult toclarify the relationship between blood lipids and the low intensity physicalactivity in humans.
More research needs to be done to understand blood lipidprofiles associated with exercise (Sugiura et al, 2002).Tudor-Locke (2010), suggested that an increase in stepcount increased the intensity of cardio vascular exercise using pedometers andstep counters based on public health recommendations (Locke et al, 2010).Morris et al. (2017), identified that adistance-based exercise prescription of walking or runningshould provide a clinician or researcher with a closer estimation of overallaccumulated exercise and resultant weight loss compared to time basedexercise.
The study involved 15 overweight, but otherwise healthy participants (Morris et al, 2017).2.10 walking with weightsBhambhani et al. (1989), conducted a study with eightphysically active young men who completed eight running tests at theirpredetermined “most comfortable” speeds with zero, 1.6, 3.2, and 4.
8kg of additional weight equally distributed on the ankles or wrists. It wasobserved that energy expenditure and heart rate increased as a linear functionof the additional weight placed at both anatomic locations (Bhambhani et al, 1989). Daneshmandi et al. (2008), studied the effect ofcarrying school backpacks on cardio-respiratory changes in 15 adolescent male studentsand recommended that the weight of school backpacks for high school studentscan be 8% of their body weight, because carrying 8% body weight load did notsignificantly change cardio-respiratory parameters (Abdullah et al, 2012).
Kubinski and Higginson (2011), recruited 40 (20 healthy,20 osteoarthritic) subjects age 40 to 85 years old and studied the effect ofchallenging weighted walking in them. It was observed that the knee OA (osteoarthritis) group increased their initial double support percent when weighted,and they had a significantly smaller step length compared to the weightedhealthy group. The smaller step length could be a result of pain potentiallyinduced during the challenging task which may have caused the knee OA subjectsto modify their walking pattern (Kubinski et al, 2012).2.11 walking uphillStachler et al.
(2010), compared cardiorespiratory responsesduring uphill versus downhill treadmill walking in healthy individuals andfound that the cardiac demands and perceived exertion responses respectively,were greater during uphill walking (Stachler et al, 2010).Mandy et al. (2013), studied the cardiovascularresponses during downhill treadmill walking in 15 participants (age 68 ± 4years) atself-selected intensity and concluded that downhill walking at a self-selectedwalking speed places a significantly reduced cardiac load on the individualcompared with level walking (Mandy et al, 2013).
2.12 Treadmill adaptabilityShimada et al. (2012), conducted a study involving 24healthy female volunteers aged over 75 years to understand gait adaptabilityand brain activity during unaccustomed treadmill walking and observed that treadmillwalking increased the cerebral cortex and cerebellum activation. Step-lengthvariability was associated with brain activation during walking. Highstep-length variability group showed relative deactivation in the hippocampus,whilst the low variability group showed relative activation in the primarysensorimotor area.
These cortical areas may be associated with gaitadaptability in older adults. These results suggested the involvement of corticalregulation in gait adaptation of the older adults. Additional studies arenecessary to examine the longitudinal sequence and relationships of gait,cognitive status, and presynaptic functional changes that emerge across thespectrum from normal aging to advanced functional decline (Shimada et al, 2013). CHAPTER 3 3.Methods and materials3.1 MATERIALSAll of the data collection for this study was performedin the Institute of Motion Analysis & research (IMAR), TORT (TaysideOrthopaedic and Rehabilitation Technology) Centre, Ninewells Hospital &Medical School, Dundee, between November 2017 and March 2018. This study wasapproved by the University of Dundee Research Ethics Committee (UREC) in November2017 and all subjects gave written informed consent prior to collection ofdata.
3.1.1 Participants 3.1.2 DemographicsData from 50 volunteers were collected. Of the 50volunteers, males (%) and females (%), median age (range), Mean height (range),mean weight (range).
All participants were healthy at the time of study, walkedregularly and had been injury free at the time of data collection. Allparticipants were fitted with stride restrictors for the second session ofwalkingIC5 . 3.1.
3 RecruitmentVolunteers were recruited personally by the researcherand through volunteer recruitment posters placed at the University of Dundeeand Ninewells Hospital campuses (Appendix 4: Recruitment Poster). Criteria ofinclusion was healthy participants aged 18 years and above who walked regularlyfor 30 minutes or more and were injury free at the time of the study. Criteriaof exclusion was lack of fitness in order to perform due to injury at the timeof data collection.3.1.4 TreadmillThe treadmill used for this study was the VisionFitness T8500.
Participants walked at their normal walking speed to which theywere accustomed to and no inclination angle was set. The treadmill delivers acontrolled and stable running environment that allows for repeatability of thesessions with and without stride restrictors.3.
1.5 Data Collecting MaterialsData was collected using a heart rate monitor and theOxycon Pro®.3.1.
6 Heart Rate monitorBefore the start of each session, the subject’s restingheart rate was recorded and then measured throughout the experiment. To ensureeach session started with the same heart rate and to decrease fatigue effectfrom one session to the next, a rest period of 30 minutes in between sessionswas incorporated. The monitor used for this study was a Wahoo Fitness: 71CXRwith appropriate heart rate strap which fits around the chestIC6 .
It is a battery powered monitor which records heart rate via skin contactsensors and sends the readings wirelessly to a connected mobile phoneapplication.3.1.7 OxyconPro®TheOxycon Pro® is anautomated open circuit metabolic cart (CareFusion, UK 236, Basingstoke,GB). It measures and collects data from a breath-by-breath gas exchangemeasurement, being used for stress testing and energy expenditure. The OxyconPro® has already shown to be a valid system to measure VO2and VCO2 at high and low exercise intensities (Rietjens et al.2001).
The system is composed of the metabolic cart, a low dead space facemaskand Triple V measuring sensors (Figure 3.3). The software LABManager® 5.31.
0.4was used to collect data and in Breath-by-Breath mode.Ventilatory volume and gas sensors were calibrated according to themanufacturer’s guidelines. Each subject was fitted with the mask before thewalking sessions. A custom report was specifically designed for this particularresearch. It exported the following parameters out of the many recorded by theOxycon Pro®: participant’s general information, VO2 ml/min and VCO2ml/min.
This data was analysed3.2 METHODSIC7 Prior to the sessions, each participant was given aninformation sheet that contained information about the research and proceduresinvolved (Appendix 2: Participant Information Sheet). In the lab, participantswere given a briefing about the study. Written informed consent was taken priorto tests (Appendix 1: Consent Form). The participants were given an option toquit at any time they wished.
All participants were fitted with heart ratestrap, facemask and the Oxycon Pro® was calibrated accordingto the manufacturer’s manual instructions. The stride restrictors were fittedfor the second session only. Each participant rested for thirty minutes afterthe first session for the heart rate to return to its resting value.Each participant completed two walking sessions of 30minutes duration on the treadmill with a 30-minute rest in between sessions.Data were collected for 30 minutes in each session.After the second session, participants were debriefedand completed research feedback forms were collected (Appendix 5: Feedback Form). IC1Youneed to back this statement up with a citation.
IC2Shouldthis not be Noakes? IC3Idon’t understand the meaning of this in this context(?) IC4Whatwas difficult to quantify? IC5Thisis not really demographic data. Probably remove from here as it is in yourMethods section. IC6Shouldyou state here how the monitor actually works? Also that is sends the data to amobile phone app(?) You should also include a section explaining what andhow the stride restrictors worked and were worn and their cost. State that thesame restrictors were used on all subjects in the same way. Also showphotographs of them (Figure 3.2). IC7Youned to state some place here what the subjects were wearing – shorts, t-shirt,shoes?