Advancing age is generally accompanied by a progressive decline in physical activity level. Age-related decline has been documented for functional fitness, including muscle strength, flexibility, balance, agility, gait velocity, and cardiorespiratory fitness. Walking has been considered to be the preferred choice of exercise among the European population [27, 28], probably because it is an accessible form of exercise that requires little expenditure, increases their individual choice in pace-setting, and has fewer risks than other forms of exercise. Participation in regular physical activity is associated with a reduced risk of many chronic illnesses and to provide many mental health benefits [3–5, 7]. The current minimum exercise recommendation associated with health benefit for each adult is to accumulate at least 30 min of moderate exercise on most days of the week [4, 6]. Walking is a very acceptable form of exercise to a wide population. It does not require any formal training or special equipment and can be performed in an individual’s locality and time [7, 8, 29]. The favorable effects of walking on both physiological and psychological well-being are firmly established . Moreover, many positive effects are reported for primary and secondary prevention of disease, plus additional psychosocial benefits . Concordant with these scientific evidence, we observed that there was a growing interest on physical activity especially walking among Turkish middle-aged and older people in our country and in city of Denizli as well. Our study was planned to examine the physical, cognitive functioning, and emotional status and quality of life in middle-aged and older adults attending to unsupervised regular walking program. The walking characteristics were defined according to aerobic exercise recommendations of American College of Sports Medicine and other authorities (at least three times a week, at least 45 min a day, and at least 1 year walking habit) .
When the participants in this study were compared in terms of occupation and education level, it was found that the participants in the regular walking group had higher education level and were consisted of retired officials. These results showed that education is an effective factor on health promotion. Another finding that attracted our attention was the number of male participants was higher than the female participants in the walking group. That means men prone to do regular exercise and to go out to participate in social activities. The physical properties of participants in the sample were similar. This shows us the homogeneity between groups. This also made the study strengthen. Another notable difference in terms of BMI and waist–hip ratio scores was found. The two scores were seen to be lower in walking group. This was an expected finding. It is well-known that regular exercise results in weight lost by increasing energy consumption and causing fat tissue destruction. A study searching the effects of different types of walking on body composition also supports that result .
We demonstrated that it is possible for community-living middle-aged and older adults to make significant gains attending in unsupervised regular walking program. All physical function parameters except handgrip improved in the participants of the unsupervised regular walking group. When the handgrip strength of participants was examined, it was seen that there was not any difference between the two groups of this study. This has also been reported in previous study by Wong et al. . The authors examined the effects of physical activity level on physical performance and physical fitness of 123 participants who were 50 years and older. They measured handgrip strength of the participants, and then they did not found any relationship between activity level and handgrip strength. This and our study explain why walking as a physical activity has no effect on upper extremities function.
Loss of balance or postural control is most noticeable during the sixth decade of life. Impaired postural balance increases the risk of falls and is often a result of inactivity related decline in lower body musculoskeletal function. A recent report suggests possible improvement in postural stability in physically active men and women. In the results of another study, it was shown that physically active elderly performed significantly better on the static and dynamic balance tests than their inactive counterparts . The results of our study also showed that regular walking as a dynamic aerobic exercise had positive effects on structures and ability of balance of the sample. Nakamura et al.  found that an exercise frequency of at least three times each week was effective on functional fitness in older adult women. The researchers found that participants who exercised three times a week showed most significant difference in the scores of walking around two cones test. We used the same test to evaluate coordination as mentioned in “Methods” section. The results of our study showed that the coordination of participants in the regular walking group were better than the inactive controls.
Gains attending in unsupervised walking program in cardiovascular fitness level were the poorest compared with the few similar studies in the related literature, especially in Turkey. This study also supports unsupervised walking program as a means of improving cardiovascular fitness. In our study, the 6-min test score was seen to be higher in the regular walking group. In some previous studies, it has been concluded that attendance to regular aerobic activities had two major effects beside psychosocial effects: (1) increased energy consumption and (2) increased cardiovascular fitness decreasing disease risk. In a meta-analysis, it was found that regular walking increased 0.6–6.9 ml kg−1 in maximal oxygen consumption . Although the results of some studies show that walking is not effective factor to increase cardiovascular fitness level, there have been many studies, including our study support that walking program can increase cardiovascular fitness of middle-aged and older people [20, 32, 33].
There were some notable differences between unsupervised walking group and inactive controls. Flexibility component of the unsupervised walking group was seen to be more improved. Teoman et al.  also reported significant difference in the flexibility of elderly women with exercise program (i.e., three times a week for 6 weeks) . The more improved flexibility for the unsupervised walking group may reflect the physical gain of regular walking program.
It is a known fact that the oxidative capacity of muscle, which is very important for muscle strength and endurance, decreases with aging. Although the effect of walking on especially lower extremity strength and endurance is controversial, it was shown that regular aerobic exercise could increase mitochondria enzyme activity and VO2max of muscle by increasing oxidative capacity . The regular walking group had better lower extremity muscle endurance than inactive participants in our study. Advancing age is generally accompanied by a progressive decline in physical activity. Age-related decline has been documented for functional fitness including muscular strength and endurance, flexibility, balance, coordination, and cardiorespiratory fitness. For years, decline in these areas was thought to be a normal and necessary consequence of aging. Our study, supported by literature, indicates that decline relates more to regular physical activity and exercise levels than age, and the physical functions of middle-aged and older adults who walk regularly are better than inactive ones.
One aspect of function that has been well established as demonstrating age-related declines is cognitive function, typically characterized by decrements in a variety of processes including aspects of memory, attention, and perception. As a modifiable risk factor, physical inactivity has been implicated in depression and cognitive decline. Promoting physical activity is an effective strategy for the maintenance of cognitive function and brain plasticity in late life. There are many clinical, experimental, and radiologic studies about the effect of exercise on cognitive functions [2, 35, 36]. Early studies regarding the relationship between physical activity and cognition, which date back at least four decades, compared the cognitive performance of low and high fit adults on an array of paper and pencil computer-based tasks. In general, these studies found that higher fit individuals were able to perform more quickly and accurately on a wide variety of perceptual, cognitive, and motor tasks than low fit individuals. In the results of these studies, a clear and significant effect of aerobic exercise was found especially on tasks that involved executive control (i.e., planning, scheduling, and working memory), and exercise effects on cognition were found to be the largest for exercise training interventions that exceeded 30 min per session. Also, in experimental studies, physical activity has been found to increase cell proliferation, cell survival, and neurogenesis in the hippocampus. Physical activity has also been found to increase levels of nerve growth factors such as brain-derived neurotrophic factor which serves to enhance synaptic efficiency. In the PET and functional MRI studies, older adults with greater levels of aerobic fitness demonstrated significantly less gray matter loss in the frontal, temporal, and parietal lobes and significantly less tissue loss in the anterior and posterior white matter tracts [35–37]. Our results support the results showing that cognitive function of the middle-aged and older adults walking regularly was better than the inactive controls.
Physical activity and exercise have been recommended as a treatment method for the successfully management of depression. The studies about the relationship between physical activity and mental health had been started since twentieth century and a lot of study was made recently. In the meetings Physical Activity, Physical Fitness and Health in France in 1992 and Surgeon’s Report in USA, it was suggested that regular physical activity decreased mild level of depression and physical activity had benefits on preventing depression regardless of any relationship with age, sex, nationality, or socioeconomic levels. Reviews of the literature on the relationship between physical activity and mental health are in broad agreement that two are positively associated [3, 36–38]. In the study by Kramer et al., 8 weeks of regular, long bouts of walking significantly enhance feelings of vigor and activity and significantly reduce feelings of tension and anxiety compared inactive participants . The results obtained from our study also showed that regular walking supported positively emotional status of middle-aged and older participants.
There is considerable and growing evidence that physical activity and/or exercise behavior plays a role in a person’s perception of quality of life [4, 8, 27]. Sedentary lifestyle increase the risk factors for HT, DM, obesity, cancer, musculoskeletal diseases, and many other diseases [6, 7, 9, 31, 39, 40]. The relationship between physical activity level and the decrease in the risk factors of these diseases has been reported in the literature [41–44]. Small but meaningful improvement in QoL can be brought about by exercise interventions over 3–6 months in well populations. Greater improvements were reported for QoL in response to moderate rather than light or vigorous exercise. However, there are few studies about the relationship between walking and quality of life. The result of our study, which shows that regular walking improves quality of life, contributes the literature in terms of relationship between physical activity, exercise, and quality of life. The more positive finding for the middle-aged and older adults walking regularly just evaluated in this study may reflect the increased social well-being and a good physical performance. This study has clearly demonstrated that even unsupervised regular walking produces changes in several aspect of health status. Moreover, this is feasible and can be suggested individuals over 45 years.
There was a limitation to the study. It was not possible to widen the sample size. Although we interviewed more than 200 potential participants, only 80 individuals who met inclusion criteria included. Most of them did not accept the invitation because of having no time to be tested.