Walking has shifted over the last few centuries from an essential mode of transport to a leisure activity. This has caused a huge decline in the amount of walking we do as modern humans which has probably had significant impacts on our health. Walking outdoors combines physical activity and exposure to nature. Both these activities have been shown to have positive effects on physical and mental health. Walking is also low-cost and accessible to a wide section of people. The science behind the benefits of walking is quite interesting. In this article I deep dive into walking and attempt to put a number on what is the optimal amount of walking one should aim for.
Impact on physical health and longevity
One of the largest studies looking at the association between walking and mortality observed 4840 participants aged 40 and older for 7 days. They measured their activity using a wearable device which measures step count and walking intensity. They then followed the participants for around 10 years on average. The study found a very clear dose-dependent effect of step count on mortality rates in this group even after adjusting for confounding variables such as age, comorbidities, smoking status, etc). The association was clear, the higher the step count the lower the mortality rate. The main causes of death were cardiovascular disease and cancer. Suggesting a protective effect of walking.
Interestingly, they did not report a similar relationship between step intensity and mortality rate. Step count seemed to be the major variable in this study. Another interesting finding is that this relationship seemed to peter out at around 10,000-12,000 steps/day suggesting that there is a point of diminishing returns around this number.
Impact on mental health
A systematic review looking at the effect of long distance walking on different markers of mental health assessed the results of 26 studies. The majority studies found a positive association between long distance walking and mental health markers they looked at. These included well-being questionnaire scores, biological markers of emotional distress and general qualitative quality of life scores. When analyzing the results further, the positive effects of long distance walking seemed to be caused by the reduction of existing levels of stress rather than addition of pleasure.
Another important aspect of long distance walking is the concept of green exercise. Many studies looking at the effect of long walking on mental health observed a synergistic effect of exercise and being in nature. As one article put it: “it seems that the presence of living things makes us feel good”. The more engaged we are in nature the more benefits we seem to get. One article describes three levels of engagement as follows: the first level is viewing nature (through a window for example). The second is being physically present in or nearby a natural environment (such as walking in a park). The third is active participation with nature (such as gardening or farming).
Green exercise seems to have additional benefits that exceed the benefits of exercise alone. Although one study challenged this notion. It found no additional benefit on emotional distress from mountain hiking when compared to treadmill walking.
What is the optimal walking prescription?
- Optimal amount: as mentioned above, it seems that 10,000-12,000 steps/day seems optimal for disease prevention and longevity.
- Optimal intensity: although intensity was not directly associated with reduction of all-cause mortality, people with higher step counts were more likely to walk at higher intensities. So it seems like higher intensity walking is better.
- Walking environment: It’s better to walk among greenery and natural environments as much as possible to get the green exercise effect.
- Footwear: use minimalist shoes. I’ll probably write a separate article on this topic but it seems that simply using minimalist shoes can be similar to a dedicated foot-strengthening program.
Is walking alone enough exercise?
It’s important to mention that although walking is greatly beneficial, it is not enough if you want to optimize your activity levels for health and longevity. Walking means you are not being sedentary which is great, but optimally, walking should be a baseline activity with shorter periods of higher intensity activities throughout the day.