Healthy Walking in your Lunch Hour – Optimising healthy walking
activity over 30 minutes
MBBS, MS Ortho
submitted in part fulfilment of the
University of Dundee
April ~ 2018
Maintaining an active lifestyle has become challenging
these days. Work demands in particular are getting in the way of exercising.
While we struggle to find time to exercise, we cannot afford to forsake
exercise because it is integral to sustained healthy success and a well-rounded
life. Physical inactivity is now estimated to be one of the leading causes of
death worldwide (World Health Organization,
2010). Prolonged sedentary behaviour can have dangerous
health consequences, including increased risk of diabetes, cardiovascular
disease and premature mortality (Hill et al, 2015).
There is emerging evidence IC1 to
suggest 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 transport
use) is being promoted as an important component of strategies to increase
physical activity levels internationally (World Health Organization,
Walking is considered as one of the safest, simplest
and most efficient forms of cardiovascular exercise and can be performed almost
anywhere. It is as effective as other forms of cardiovascular exercise and does
not require expensive equipment or regular visits to a gym (Siegel et al, 1995). Walking is a great
exercise for all ages and in some
cases, it can be more effective than
running however a good walking technique is very important to maximise the
results. Walking, as opposed to running, is an
exceptionally safe activity, since it involves having one leg always in contact
with 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) concluded
that walking is the basic form of physical activity necessary for maintaining
good health and should be an inseparable part of a healthy everyday lifestyle,
including working days (World Health Organization,
The recommended amount of exercise for adults is 150 minutes of moderate
physical activity per week. That breaks down to 30 minutes of exercise over
five days a week (World Health Organization,
The American Heart Association
Recommended the same in 2015 and updated them in 2017 (American
Heart Association, 2017).
Although many techniques have been proposed to increase
the efficiency of walking over shorter duration of exercise such as the use of
weights, brisk walking, uphill walking and so on, there is no significant
emphasis on shortening of stride length to improve the intensity of
cardiovascular exercise. Shorter strides while walking increase the step count
and may increase cardiovascular exercise over a 30-minute period compared to
normal/regular strides. There is not a similar study in the available literature
which has evaluated the effects of shorter strides during walking on
cardiovascular exercise. Hence, the reason for conducting this current study in
comparing the outcome.
The study included 50 subjects who normally walk for
thirty minutes or more each day. They will be subjected to a single 90-minute
session comprising two 30-minute walking and one 30-minute rest phase in
between where data will be collected. There will be no follow up and the data
will be analysed after the sample size has been reached.
Previous studies have indicated that slower walking
speed in elderly subjects may be associated with decreased joint movements and
joint kinetics (Kerrigan et al, 2000), (Kerrigan et al, 2001) biomechanical changes (DeVita and Hortobagyi,
and in choosing “cautious” gait strategy (Winter et al, 1990).
Treadmill walking, in theory, is mechanically
equivalent 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 to
familiarize themselves with the treadmill (Taylor et al, 1996), (Matsas et al, 2000). However, complete
familiarization with a treadmill even in a 15-min single session was not
attained in many elderly adults (Wass et al, 2005).
Therefore, in this current study the normal walking
speed on the treadmill will be defined according to preference of individual
Aims & objectives
To determine whether the use of a stride restrictor
while walking alters cardio vascular exercise.
To study the effect of stride changes on heart rate
and maximal oxygen consumption.
To determine whether a change in stride length can alter
cardiovascular exercise over a 30-minute period.
Of all types of physical activity, walking stands out
as the most popular form of leisure time exercise (Ham et al, 2009), and can be easily performed
at moderate intensity (Murtagh et al, 2002).
Various studies have been conducted to understand the
benefits of walking as a cardiovascular exercise. Although it has been proved
to be safer and as effective as any other form cardiovascular exercise. Many
research projects have proposed ways of maximising the efficiency of walking to
achieve the same results with a shorter duration of exercise.
Physical activity and aerobic fitness
Noakes IC2 et al. (2009), found that cardio respiratory fitness is more a function of the
intensity of physical activity than its volume in middle-aged women in a study
of 275 women (40.1+/-3.0 years) (Noakes, 2009).
et al. (2013), identified that an increased physical activity level over
a one year period resulted in increased aerobic fitness in severely obese
subjects. Although the sample size was small (21 subjects, mean age 42), these
results suggest that change in 6-minute walking test may not be a good
indicator of maximal change in aerobic fitness in this population (Adland et al, 2013).
Laudani et al. (2013), conducted a study that included
72 volunteers and concluded that there is a significant association between physical
activity levels and physiological determinants of mobility in young,
middle-aged and older individuals living in a city district, with significant
differences in the relative role played by volume and intensity of overall physical
activity and selected habitual activities. While aerobic function was
associated to the volume of activity, neuromuscular function and functional
abilities showed a significant association exclusively with the intensity of
physical activity (Ludini et al, 2013).
Physical activity and Disability
Nusselder et al. (2008), identified that performing moderate
to high levels of non-occupational physical activity reduced incidence, and
showed a higher gain in disability-free years (male 4.1; female 4.7), also a
similar reduction in years with disability (Nusselder et al, 2008).
Physical activity and work
Naughton et al. (2010), conducted a survey in 2010 in
which 44 employees from a health provider (Health) and 63 employees from a
public-sector organisation (PSO) underwent a self-completed questionnaire
enquiring about a broad range of workplace-based exercise issues and identified
that overall, employees from Health and PSO were positive about the policies at
work to encourage exercise but further work was required to
ensure that public health guidance was aimed at improving exercise at work so
that it has maximal worker benefit (Naughton et al, 2010).
McKay et al. (2015), conducted a cross sectional study
of 2,122 adults aged 18 years and above in rural India and Bangladesh and found
that those that achieved the recommended weekly physical activity levels
through work-based activity were more likely to achieve it. The only problem in
this study according to the author was physical activity data were based on
self-reporting similar to the International Physical Activity Questionnaire
(IPAQ), which has been associated with overestimation of physical activity
levels (McKay et al, 2015).
Effect of environmrnt
Handy et al. (2002), published an evidence based study
that was aimed at understanding the interrelationship between the built
environment and human behaviour and then to develop models that predicted the
environmental conditions under which humans will be more physically active.
The study identified that walking and cycling have been
more popular and successful modes of exercise than other forms of travel because
they are relatively easy for the vast majority of the population and offer
relatively little risk of injury.
It was concluded that that a combination of urban
design, land use patterns, and transportation systems that promote walking and cycling
will help create active, healthier, and more liveable IC3 communities (Handy et al, 2002).
Brownson et al.
(2005), identified that
it was difficult to precisely quantify IC4 owing to the lack of long-term data, a
combination of characteristics of the built environment and increases in the
proportion of the population engaging in sedentary activities that put the
majority of the American population at high risk of physical inactivity.
concluded that a complex interaction of cultural, social, economic, and
familial issues has likely set the stage for these changing physical activity
trends (Brownson et al, 2005).
Mytton et al. (2017), conducted a study involving 7689
working men in the UK to understand the associations of active commuting with
body fat and visceral adipose tissue and identified that walking and cycling to
work was associated with reduced adiposity relative to exclusive car-use (Mytton et al, 2017).
Kocur et al. (2012), conducted an evidence based study
and recommended parameters of walking training which can be applied to primary
and secondary cardiac prevention (Kocur et al, 2012).
Table 2.1: Kocur et al, parameters of
walking training which can be applied to primary and secondary cardiac
Atalay & Cavlak (2012), studied the impact of
unsupervised regular walking on health in a sample of 40 Turkish middle-aged
and older adults with a mean age of 56.30 ± 4.85 years (range 40–70) walking
for at least 1 year, at least three times a week, and at least 45 min a day and
40 inactive participants with a mean age of 55.15 ± 5.64 years (range 40–70) and
concluded that unsupervised regular walking improves health and is also a safe,
cheap, and can easily be adapted into daily life. Therefore, it can be
recommended 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 94
volunteers aged 18+ and found that differences in prior expectations that motivate
people to participate in a training program can augment or reduce the chances
of completing the exercise protocol as 73
volunteers (77.6% of the entire sample – 40 women) did not complete the
protocol, and 21 volunteers (13 women) completed the full 1-year exercise protocol.
The expectation of social interaction was a positive
factor in predicting maintenance of an exercise program and suggested that
structuring physical exercise sessions would facilitate socialization and may
increase adherence (Rosa et al, 2018).
Duration of walk
Harvey et al. (2017), observed in 10 healthy volunteers
that 30?minutes of moderate intensity physical activity can be accumulated in
continuous bouts of at least 10?minutes but it was shown by use of activity monitoring
that it was difficult to achieve 10?minutes of completely uninterrupted walking
in 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 in
walking had no significant effect on the VO2 kg min?1.
However, two breaks of 50?seconds or 100?seconds introduced into a 5-minute
brisk walk showed a significant reduction in oxygen uptake requirements and
metabolic equivalent of task (MET) (p?0.001) compared to continuous walking for the same amount of effective walking (Harvey et al, 2017). 2.8 speed of walk Murtagh et al. (2002), observed in 82 subjects aged between 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). Chung and Wang (2009), studied 30 healthy male and female subjects aged between 20-80 and observed that the preferred walking speed (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 vigorous physical activity was negatively associated with slow walking speed, independent from step counts and confounders (Takuji et al, 2018). 2.9 distance of walk Sugiura (2002) conducted a study involving 48 menopausal women (age: 40–60 years) and observed that daily exercise as well as increasing the number of daily steps as a moderate exercise can improve the profile of serum lipids in menopausal women. However, it is difficult to clarify the relationship between blood lipids and the low intensity physical activity in humans. More research needs to be done to understand blood lipid profiles associated with exercise (Sugiura et al, 2002). Tudor-Locke (2010), suggested that an increase in step count increased the intensity of cardio vascular exercise using pedometers and step counters based on public health recommendations (Locke et al, 2010). Morris et al. (2017), identified that a distance-based exercise prescription of walking or running should provide a clinician or researcher with a closer estimation of overall accumulated exercise and resultant weight loss compared to time based exercise. The study involved 15 overweight, but otherwise healthy participants (Morris et al, 2017). 2.10 walking with weights Bhambhani et al. (1989), conducted a study with eight physically active young men who completed eight running tests at their predetermined "most comfortable" speeds with zero, 1.6, 3.2, and 4.8 kg of additional weight equally distributed on the ankles or wrists. It was observed that energy expenditure and heart rate increased as a linear function of the additional weight placed at both anatomic locations (Bhambhani et al, 1989). Daneshmandi et al. (2008), studied the effect of carrying school backpacks on cardio-respiratory changes in 15 adolescent male students and recommended that the weight of school backpacks for high school students can be 8% of their body weight, because carrying 8% body weight load did not significantly 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 of challenging weighted walking in them. It was observed that the knee OA (osteo arthritis) group increased their initial double support percent when weighted, and they had a significantly smaller step length compared to the weighted healthy group. The smaller step length could be a result of pain potentially induced during the challenging task which may have caused the knee OA subjects to modify their walking pattern (Kubinski et al, 2012). 2.11 walking uphill Stachler et al. (2010), compared cardiorespiratory responses during uphill versus downhill treadmill walking in healthy individuals and found that the cardiac demands and perceived exertion responses respectively, were greater during uphill walking (Stachler et al, 2010). Mandy et al. (2013), studied the cardiovascular responses during downhill treadmill walking in 15 participants (age 68 ± 4years) at self-selected intensity and concluded that downhill walking at a self-selected walking speed places a significantly reduced cardiac load on the individual compared with level walking (Mandy et al, 2013). 2.12 Treadmill adaptability Shimada et al. (2012), conducted a study involving 24 healthy female volunteers aged over 75 years to understand gait adaptability and brain activity during unaccustomed treadmill walking and observed that treadmill walking increased the cerebral cortex and cerebellum activation. Step-length variability was associated with brain activation during walking. High step-length variability group showed relative deactivation in the hippocampus, whilst the low variability group showed relative activation in the primary sensorimotor area. These cortical areas may be associated with gait adaptability in older adults. These results suggested the involvement of cortical regulation in gait adaptation of the older adults. Additional studies are necessary to examine the longitudinal sequence and relationships of gait, cognitive status, and presynaptic functional changes that emerge across the spectrum from normal aging to advanced functional decline (Shimada et al, 2013). CHAPTER 3 3. Methods and materials 3.1 MATERIALS All of the data collection for this study was performed in the Institute of Motion Analysis & research (IMAR), TORT (Tayside Orthopaedic and Rehabilitation Technology) Centre, Ninewells Hospital & Medical School, Dundee, between November 2017 and March 2018. This study was approved by the University of Dundee Research Ethics Committee (UREC) in November 2017 and all subjects gave written informed consent prior to collection of data. 3.1.1 Participants 3.1.2 Demographics Data from 50 volunteers were collected. Of the 50 volunteers, males (%) and females (%), median age (range), Mean height (range), mean weight (range). All participants were healthy at the time of study, walked regularly and had been injury free at the time of data collection. All participants were fitted with stride restrictors for the second session of walkingIC5 . 3.1.3 Recruitment Volunteers were recruited personally by the researcher and through volunteer recruitment posters placed at the University of Dundee and Ninewells Hospital campuses (Appendix 4: Recruitment Poster). Criteria of inclusion was healthy participants aged 18 years and above who walked regularly for 30 minutes or more and were injury free at the time of the study. Criteria of exclusion was lack of fitness in order to perform due to injury at the time of data collection. 3.1.4 Treadmill The treadmill used for this study was the Vision Fitness T8500. Participants walked at their normal walking speed to which they were accustomed to and no inclination angle was set. The treadmill delivers a controlled and stable running environment that allows for repeatability of the sessions with and without stride restrictors. 3.1.5 Data Collecting Materials Data was collected using a heart rate monitor and the Oxycon Pro®. 3.1.6 Heart Rate monitor Before the start of each session, the subject's resting heart rate was recorded and then measured throughout the experiment. To ensure each session started with the same heart rate and to decrease fatigue effect from one session to the next, a rest period of 30 minutes in between sessions was incorporated. The monitor used for this study was a Wahoo Fitness: 71CXR with appropriate heart rate strap which fits around the chestIC6 . It is a battery powered monitor which records heart rate via skin contact sensors and sends the readings wirelessly to a connected mobile phone application. 3.1.7 Oxycon Pro® The Oxycon Pro® is an automated open circuit metabolic cart (CareFusion, UK 236, Basingstoke, GB). It measures and collects data from a breath-by-breath gas exchange measurement, being used for stress testing and energy expenditure. The Oxycon Pro® has already shown to be a valid system to measure VO2 and VCO2 at high and low exercise intensities (Rietjens et al. 2001). The system is composed of the metabolic cart, a low dead space facemask and Triple V measuring sensors (Figure 3.3). The software LABManager® 126.96.36.199 was used to collect data and in Breath-by-Breath mode. Ventilatory volume and gas sensors were calibrated according to the manufacturer's guidelines. Each subject was fitted with the mask before the walking sessions. A custom report was specifically designed for this particular research. It exported the following parameters out of the many recorded by the Oxycon Pro®: participant's general information, VO2 ml/min and VCO2 ml/min. This data was analysed 3.2 METHODSIC7 Prior to the sessions, each participant was given an information sheet that contained information about the research and procedures involved (Appendix 2: Participant Information Sheet). In the lab, participants were given a briefing about the study. Written informed consent was taken prior to tests (Appendix 1: Consent Form). The participants were given an option to quit at any time they wished. All participants were fitted with heart rate strap, facemask and the Oxycon Pro® was calibrated according to the manufacturer's manual instructions. The stride restrictors were fitted for the second session only. Each participant rested for thirty minutes after the first session for the heart rate to return to its resting value. Each participant completed two walking sessions of 30 minutes 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 debriefed and completed research feedback forms were collected (Appendix 5: Feedback Form). IC1You need to back this statement up with a citation. IC2Should this not be Noakes? IC3I don't understand the meaning of this in this context(?) IC4What was difficult to quantify? IC5This is not really demographic data. Probably remove from here as it is in your Methods section. IC6Should you state here how the monitor actually works? Also that is sends the data to a mobile phone app(?) You should also include a section explaining what and how the stride restrictors worked and were worn and their cost. State that the same restrictors were used on all subjects in the same way. Also show photographs of them (Figure 3.2). IC7You ned to state some place here what the subjects were wearing - shorts, t-shirt, shoes?