Sports Medicine 16 (6): 369-373, 1993 0112-1642193100 12-0369/$02.50/0 © Adis International Limited. All rights reserved.

Is Walking Sufficient Exercise for Health?

R.e. Richard Davison and Stanley Grant

Department of Physical Education and Sports Science, University of Glasgow, Glasgow, Scotland

Several epidemiological studies have shown a clear association between inactivity and a higher risk of mortality, in particular from coronary heart disease (CHD) [Blair et al. 1989; Brill et al. 1992; Hagan et al. 1991; Leon et al. 1987; Morris et al. 1990; Paffenbargeret al. 1984, 1993; Sandvik et al. 1993; Wannamethee & Shaper 1992]. The Allied Dunbar National Fitness Survey (ADNFS) [1992] of England and Wales found that 70% of men and 80% of women were under the desired activity level for their age group.

Interestingly, another finding of the ADNFS was that walking continuously for at least 1 mile was an activity pursued by just over half ofthe men and women in the sample. The popularity of walk-ing lies in the fact that it is easy to do, requires no special skill, requires no facilities, and is achiev-able by virtually all age groups with little risk of injury. Walking can take many forms, for example, race walking, power walking, aerobic walking, health walking, mall walking, hill walking and walking the golf course.

Several studies of walking have shown consid-erable health benefits for all age groups, with im-proved aerobic fitness (Davison et al. 1992; Dun-can et al. 1991; Hamdorf et al. 1992; Hardman et al. 1989a, 1992; Jette et al. 1988; Rowland et al. 1991), reduced body mass (Ohta et al. 1990), lower body fat (Ohta et al. 1990; Pollock et al. 1971), a fall in blood pressure (Davison et al. 1992; Ohta et al. 1990) and improved blood lipid profile (Davi-

son et al. 1992; Duncan et al. 1991; Hudson et al. 1988; Ohta et al. 1990).

In the following guest editorial, walking as an exercise will be briefly discussed in relation to blood pressure, lipid and cholesterol levels, body composition, mental health, osteoporosis, aerobic power and orthopaedic problems.

1. Blood Pressure

Regular aerobic exercise is associated with de-creases in systolic and diastolic blood pressure in mild and moderate hypertension (Cade et al. 1984; Duncan et al. 1985; Nelson et al. 1986). Most stud-ies on walking have included only normotensive people. While some studies have demonstrated a small but significant decrease in blood pressure (Davison et al. 1992; Ohta et al. 1990; Pollock et al. 1971; Porcari et al. 1988; Whitehurst & Men-endez 1991), others with similar initial readings have failed to show a significant reduction in blood pressure (Duncan et al. 1991). Comparisons with other studies which have employed nonwalking exercise modes with normotensive study partici-pants have revealed a similar situation. A dramatic fall in blood pressure is unlikely as it is not possible to reduce blood pressure in the normal range by a large amount.

2. Lipids

Many studies that have investigated the effect of aerobic exercise on lipids have produced con-

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flicting findings. These inconsistencies may be ex-plained by the initial baseline lipid level, variety of training stimulus used in the different studies, the lack of dietary analysis and the confounding factor of changes in body composition during training. There is consensus that training studies of 12 weeks or longer are associated with an increase in high density lipid (HDL) cholesterol (Wood et al. 1988). Several walking studies have resulted in in-creases in HDL cholesterol in men and women of a wide age range (Duncan et al. 1991; Hamdorf et al. 1992; Hardman et al. 1989a; Leon et al. 1979; Whitehurst & Menendez 1991).

Duncan and colleagues (1991) speculated that the exercise prescription needed to increase HDL cholesterol may be different from that required to promote increases in aerobic power. Women who walked at low intensity (,strollers') showed the same increase in HDL cholesterol as those who carried out the same frequency and duration of ex-ercise but completed the training distance faster than the strollers ('aerobic walkers'). In this 24-week study the aerobic walkers showed a 16% in-crease in V02max, whereas the strollers demon-strated only a 4% improvement in V02max.

Cook et al. (1986) and Tucker and Friedman (1990) also found that low intensity, long dura-tion walking played an important role in in-creasing HDL cholesterol or improving the total cholesterol: HDL ratio.

3. Body Composition

A considerable number of investigators have examined the effects of aerobic exercise on body composition. Wilmore (1983) reviewed 55 studies on aerobic exercise (training duration 6 to 104 weeks) and body composition, and concluded that mean decreases in body fat of 1.6% were minimal. He stressed that tighter control of energy intake and energy expenditure must be made to clarify some of the discrepancies in the area.

Several studies have shown that walking can de-crease the percentage of body fat and/or body mass in men and women (Pollock et al. 1971, 1975; White et al. 1984). Combined with dieting, brisk

Sports Medicine 16 (6) 1993

walking has been shown to be very effective at re-ducing weight and body fat in obese individuals (Ohta et al. 1990). In the 16-week detailed study of Leon and coworkers (1979), 6 obese males walked for 90 minutes per day, 5 days per week on a tread-mill. These individuals showed a decrease of 5. 7kg in body mass and a fall of 6% in percentage body fat. Daily food intake increased initially, but later decreased to below pretraining levels. However, a number of walking studies have failed to demonstr-ate any change in body composition (Davison et al. 1992; Duncan et al. 1991; Hardman et al. 1992; Rowland et al. 1991; Santiago et al. 1987).

4. Mental Health

Regular aerobic exercise has been shown to pro-mote a feeling of well-being (Brown 1990). Some walking studies have also demonstrated benefits in mental health. Porcari et al. (1988) found that 36 middle aged males and females had a reduced state anxiety after 40 minutes of treadmill walking at varying intensities on different occasions. Brisk walking (45 minutes, 5 times per week) resulted in an increase in general well-being as assessed by Cramer et al. (1991).

5. Osteoporosis

Osteoporosis often results in fracture of the ver-tebrae or femur in older women. Exercise can in-crease bone density and it is estimated to reduce the risk of fracture by as much as a half, preventing, for example, some 20 000 fractures each year in England and Wales (Law et al. 1991). A small num-ber of studies have examined the effect of walking programmes and the development of osteoporosis. Findings have ranged from no apparent benefit (Cavanaugh & Cann 1988), to suggestions that reg-ular walking may result in positive effects (Sandler et al. 1987; Nelson et al. 1991).

6. Aerobic Power

Many studies have shown that regular aerobic exercise carried out 3 times per week for 30 min-utes or more at intensities at or above 50% V02max

Walking as Exercise for Health

will result in increases in aerobic power in pre-viously sedentary individuals (American College of Sports Medicine 1990). These guidelines hold for a variety of exercise modes including walking. However, some studies have demonstrated that un-fit, middle aged men improved their aerobic power while exercising at around or under 45% V02max (Badenhop et al. 1983; Gossard et al. 1986).

Generally, walking is not perceived as physical exercise, but Porcari et al. (1987) were able to demonstrate that for the majority of men and women fast walking on the flat was able to elicit heart rates high enough to give an adequate train-ing stimulus. The effects of a walking programme on aerobic power have ranged from large to quite modest improvements, over a wide range of age groups. The middle-aged men and women of the Jette et al. (1988) study improved aerobic power by 17% and 10% respectively, after a 12-week pro-gramme of walking 3 times per week for 30 min-utes per session at 60% V02max. 32 women (30 to 62 years of age) followed a 3-month programme of walking for 200 minutes per fortnight increasing to 350 minutes by the end of 3 months. V02max increased from 27.0 to 29.1 ml/kg/min (Hardman et al. 1989b). After 11 weeks of walking 3 days per week at 80% of maximum heart rate, Rowland et al. (1991) found a 10% increase in aerobic power in predominantly obese teenagers.

7. Orthopaedic Problems

Some studies have suggested that walking has an advantage over some other modes of exercise as it places less stress on bones and joints resulting in a reduced incidence of musculoskeletal injuries. Santiago and colleagues (1987), in a comparison of walking and jogging programmes for sedentary women, found that for similar physiological im-provements the jogging programme had a 40% drop-out rate because of musculoskeletal injuries, whereas only 7% of the walkers dropped out due to injury.

8. Walking: How Much is Enough for Health?

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Research has confirmed that there is an inverse relationship between CHD and physical activity. Blair et al. (1992) referred to epidemiological data when they suggested that the most sedentary sec-tion of the population 'would receive clinically sig-nificant health benefits' if this category of adults underwent 30 minutes of walking per day. It is con-sidered that these health benefits would span a range of chronic diseases leading to a reduced risk of morbidity and mortality.

It is not clear in the literature what intensity of exercise is required to improve health. Wenger and Bell (1986) in their review concluded that for the most effective gains in V02max an intensity of 90 to 100% V02max was needed. Some of the large epidemiological studies suggest that there may be a 'dose response' to the amount of physical activity (Blair et al. 1989; Duncan et al. 1991; Jette et al. 1992; Leon et al. 1987; Morris et al. 1990; Paffen-barger et al. 1993; Sandvik et al. 1993) and that even low levels of exercise can give health bene-fits. Most of these studies have classified physical activity in terms of energy expenditure. Although this figure is useful, it may be limited in that the intensity of exercise may well determine some of the possible benefits. Thus, in terms of health improvement, there is considerable debate as to whether there is a threshold intensity or a dose re-sponse, and indeed the answer may differ depend-ing on the health variable. A review of recent studies involving walking shows that in terms of intensity they all exceed the American College of Sports Medicine (1990) guidelines minimum, but that not all of the health related variables show im-provement (table I). Therefore, the simple health message should be 'any walking is better than none at all, but longer and faster walks can lead to greater improvements' .

9. Conclusions

The findings of many walking studies dem-onstrate that regular walking provides an adequate

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Table I. Studies of walking which specify training intensities, showing their effects on aerobic power, lipid profile, body composition and blood pressure

Reference Participants Exercise intensity Duration Effect

sex age number aerobic lipid body blood (years) power profile composition pressure

Davison et al. (1992) M 40-60 46 70-75% HRmax 14 weeks I I ~ J,.

Duncan et al. (1991) F 20-40 16,12, 86,67,56% HRmax 24 weeks I I ~ ~

18

Hardman et al. (1989) F 44.9a 28 60% predicted \i'02max 12 months NM I NM NM

Hardman et al. (1992) F 44.9a 28 80% HRmax 12 months I NM ~ NM

Jette et al. (1988) F,M 35-53 12, 14 60% \i'02max 12 weeks I NM NM NM

Pollock et al. (1971) M 40-56 16 63-76% HRmax 20 weeks I NM I J,.

Rowland et al. (1991) F,M 15.7a 1,14 80% HRmax 3 months I NM ~ NM

Santiago et al. (1987) F 9 71% HRmax 11 weeks I ~ ~ NM

Whitehurst & F 61-81 34 70-80% predicted 8 weeks I I I J,. Menendez (1991) HRmax

a Mean value. Abbreviations and symbols: HRmax = maximum heart rate; NM = not measured; ~ denotes no significant change; I denotes significant improvement; J,. denotes significant decrease.

stimulus for many young, middle aged and elderly people to achieve significant gains in aerobic pow-er. At an appropriate pace, walking may be superior to jogging as an introduction to regular exercise, especially for overweight or extremely unfit indi-viduals. The available evidence suggests that even a moderate amount of regular walking has the po-tential to lower blood pressure, improve the lipid profile, reduce body fat, enhance mental well-be-ing and reduce the risk of coronary heart disease. Walking has advantages over other modes of exer-cise. It is possible to walk almost anywhere, and at any time. The likelihood of injury is lower in walk-ing compared with other exercise modes. Walking is an activity that can be undertaken by all ages and offers the possibility of a wide range of health ben-efits. In general, walking affords an excellent op-portunity to incorporate some form of regular ex-ercise into a healthier lifestyle.

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Correspondence and reprints: R. C. Richard Davison, Department of Physical Education and Sports Science, University of Glasgow, 77 Oakfield Avenue, Glasgow G 12 8LT, Scotland.