Non-communicable diseases including cardiovascular disease, diabetes, cancer and chronic respiratory disease caused 36 million deaths world-wide in 2008
]. Cardiovascular disease (CVD) is one of the biggest killers in the UK with 193,000 deaths per year (39% of deaths) with huge economic costs (estimated at £30 billion a year in UK)
]. Furthermore, CVD represents 50% of all European deaths, although 80% of heart disease and stroke incidences are often preventable
]. Modifiable cardiovascular risk factors include hypertension, hyperlipidemia, physical inactivity, smoking, obesity and diabetes. Some of these modifiable risks can be reduced by increasing physical activity, with a 20-30% greater risk for CVD in those not engaging in regular physical activity
]. In England, less than 40% of men and 30% of women
] meet the Government guidelines which are to perform 150 minutes of moderate exercise per week (like brisk walking), or 75 minutes of vigorous physical activity (like jogging or running), or a combination of both in bouts of at least 10 minutes, on a weekly basis
Increasing physical activity does have a range of health benefits but many studies focus on weight loss as a primary outcome. However, a recent article
] suggests that to determine the beneficial effects of health, body mass should not be the main outcome measure but other markers of health should be assessed including resting and exercising heart rate (HR) and HR recovery (HRR) post-exercise. A slow HRR post-exercise, which is governed at least in part by the autonomic nervous system (ANS) via parasympathetic reactivation, may increase the susceptibility to ventricular fibrillation in patients with ischemic heart disease
]. HRR post-exercise is also an independent predictor of mortality across large and diverse populations, whether maximal or sub-maximal exercise is performed
]. HRR following exercise may be a better predictor of cardiovascular risk than ECG monitoring, particularly if HRR is combined with cardiorespiratory fitness level another predictor of cardiovascular health
]. Improvements in cardiorespiratory fitness, irrespective of being considered overweight, can reduce the risk of mortality by all causes and can reduce risk to a greater extent for death from cardiovascular disease
]. All individuals, therefore, should be encouraged to undertake physical activity
The alterations that are seen in HR by regular physical activity may in part be due to the adaptation of the ANS
]. ANS control can be studied using heart rate variability (HRV). HRV is a well-established non-invasive tool which gives an indication of the changes in vagal and potentially sympathetic control of the heart
]. Evidence suggests that low HRV at rest and during exercise may show independent risk for cardiovascular mortality
]. Reductions in cardiac parasympathetic control i.e. lower baroreceptor sensitivity are highly predictive of cardiovascular mortality
] and augments the risk of sudden death due to malignant arrhythmias
] particularly in the presence of increased sympathetic drive, as occurs during myocardial ischemia
]. In previous studies, exercise training has been shown to increase resting HRV, via increases in parasympathetic control of the heart
]. Exercise training may induce its benefits by altering compliance of the heart and blood vessels, resulting in arterial remodelling of the great vessels, particularly in barosensitive areas and cardiovascular control centres, leading to alterations in parasympathetic outflow
Low HRV is not only linked to CVD but has also been linked to other diseases including diabetes and depression, and also to stress
]. The normal response to stress is to induce neuroendocrine changes, which includes the ANS on the neural side, and the hypothalamic-pituitary-adrenal (HPA) axis on the endocrine side. The responses are important as they initiate the fight and flight response, allowing appropriate adaptation to the stress. However, dysregulation of both the ANS and the HPA axis can occur if i) the stress is a major threat, ii) the stressor response is exaggerated, iii) the stress is repetitive and/or iv) recovery following the stressor is attenuated
]. This can then lead to chronic stress or allostatic load
]. Alterations in HPA axis can also lead to disturbances in cortisol production, a biochemical marker of stress
]. Changes in this neuroendocrine response to stressors, with the additional alterations in between behaviours related to stress such as increased smoking, increased alcohol consumption and physical inactivity
] might explain the association between allostatic load and an increased risk of CVD, specifically coronary heart disease (CHD). Furthermore, stress and lack of time are common factors that are quoted as contributing to reductions in daily physical activity.
Stress is becoming increasingly present in our everyday lives and it is important to explore methods that may help reduce stress, especially as chronic stress can also indirectly cause alterations in behaviours in particular decreased physical activity. Workplace may be a major contributory factor. Cross-sectional studies investigating work stress in men have been associated with repeated activation of the ANS characterised by reductions in HRV
]. Chronic stress in the workplace is also associated with greater levels in evening salivary cortisol
]. Consequently, it is important to find methods of encouraging people to become active in an enjoyable way which are sustainable and promote adherence.
Walking is an activity that could be incorporated easily into a working day. Unlike the majority of other physical activities, no specialist equipment is required, apart from maybe a change of shoes and with little need for a shower after the walk. Achieving a certain amount of walking steps per day might significantly contribute to the requirements for moderate physical activity for health benefits
Pedometers have been previously used in interventions not only to measure physical activity by assessing number of steps but also are an effective tool for increasing walking activity in sedentary workers
]. Number of steps has been related to reductions in resting heart rate and waist circumference when compared to baseline
] and improvements in quality of life and work performance
]. The pedometers help to increase general activity throughout the day
]. In one workplace intervention study, steps/day average increased above pre-intervention levels by 968 steps per day in 179 white collar university workers
] but no change in sitting time was observed. Although it is difficult to establish an adequate number of walking steps, adults who accumulated at least 10,000 walking steps daily showed decreased body fat and lower BP levels than individuals who did not reach this figure
]. A limitation of pedometers, however, is at the data retrieval stage, where participants generally need to log activity and data is only collected as a whole day rather than time stamping physical activities throughout the day. Other ways of retrieving physical activity may help to improve the assessment of interventions.
As 50-60% of waking hours are spent at, workplace interventions should be implemented to increase physical activity
]. Recent recommendations suggest that companies should engage in programmes that improve the health and wellbeing of their employees through specific non-communicable disease prevention schemes and the promotion of healthy lifestyles
]. Current guidelines suggest that employers should encourage more active transport to and from work, more moving within the working day and promote walking during work breaks
]. Workplace interventions aimed at changing physical activity and dietary patterns can reduce CVD risk factors such as blood pressure (BP), cholesterol and body mass index (BMI)
]. Increased levels of walking can also benefit endpoint outcomes (mortality) on CVD
]. A meta-analysis of workplace physical activity interventions showed participation can have positive effects on fitness, anthropometric measurements as well as work attendance and job stress
]. A review of 13 intervention trials (8 randomised control and 7 observational studies) concluded that change in physical activity patterns during the working day can also improve psychosocial health
Increasing activity within the working day especially during lunchtime may help to increase overall activity levels. Not only can increases in physical activity and breaks during the day have benefits for the individual but they are deemed to also benefit the employer
An intervention needs to be cost efficient and sustainable in the long-term for them to be effective. This is particularly important in the workplace as companies do not always have large budgets to dedicate to health interventions. Employers, particularly in UK, are not yet aware of the cost to benefit ratio as it more difficult to assess than in the USA where companies pay for the health care of their employees. Further, physical activity interventions in the workplace that have both physiological and psychological benefits, at low cost would be invaluable in reaching a wide working population.
Physical activity levels may be increased by being within nature and/or green space whether it is managed parks, trails or more remote unmanaged environments
]. Interestingly, is physical activity when combined with nature, it may also have enhanced benefits. Nature may offer reductions in both stress and mental fatigue
], which would be an additional benefit to individuals and employers during work time. Thus, the combination of nature and exercise during lunchtime may offer a simple and inexpensive solution to increasing physical activity levels and reducing stress
]. The combination of exercise in nature has been called “green exercise”
] and the synergistic action of nature and the physical activity may increase the benefits of physical activity. In terms of physiological measures, in a laboratory study, BP was lower 5 minutes post-exercise after viewing images of nature compared to exercising whilst viewing images of built environments
]. Walking or sitting in a natural (forest) environment has also been shown to lower HR and BP when compared to a built environment control
]. Park and colleagues suggest that an increase in parasympathetically mediated HRV, with simultaneous decreases in sympathetic components is responsible for the observed reductions in HR and BP
]. This is supported by the observation that viewing nature alone, within a laboratory, increases parasympathetic activity and overall HR variability
]. Another study, where walking outdoors in natural environments was used, BP was reduced with a trend to reduced urinary noradrenaline, inferring that this was driven by a decrease in sympathetic stimulation
]. Prior viewing of nature has also been shown to increase vagal activity following a stressor, suggesting an enhanced recovery (unpublished) and a potential reduction in allostatic load. Nature also impacts on psychological markers of health increasing both mood and self-esteem
], with only 5 minutes of exposure to the natural environment having a large effect
Incorporating “green exercise” into a workplace intervention may have a greater influence on modifiable risk factors for non-communicable diseases, than exercise alone or in built environments. The use of nature as part of a walking intervention in the workplace is a novel approach and the aim of the current study was to investigate whether using “green exercise” as an intervention, improves cardiovascular markers and stress, whilst also enhancing physical and psychological health compared to exercise in a built environment. Furthermore, it was explored whether nature may improve adherence rates.
To date few studies have used robust data collection methods to measure the impact of workplace interventions on employees’ physical activity levels and health markers
]. This study was designed to address this by including methods that were both objective and subjective: physical activity monitoring; physical, physiological and psychological markers of health.
In summary, this study posed the following primary research questions:
1. Can walking at lunchtime induce changes in cardiovascular markers that have been previously linked to health?
2. Are the changes modified by the type of walking environment?
Secondary research questions included:
1. What are the effects of walking at lunch time on other markers of health and stress levels?
2. Can a lunch time walking intervention increase overall physical activity (both within and outside work)?
3. Are fitness levels and HRR from exercise and stress altered by walking environment?
4. Does the walking environment affect health outcomes (including stress) and adherence to weekly walks?
5. Do participants have a preference to a particular walk and thus does choice of walk affect adherence?
6. How feasible is it to introduce an 8-week walking intervention to a workplace?
7. At 3
month follow-up what effect is there on health markers?