Friday, December 28, 2012

Walking as a Form of Exercise

Meet Mary. Mary is a sedentary 68 year-old woman who, like many others, is looking to start an exercise program at the start of the new year. She has recently suffered from knee pain, sees her balance slowly digressing, and is worried about developing arthritis after seeing her mother struggle with it in her latter years. Overall, Mary is looking to improve her health and physique. She walked often in recent years and her plan is to take morning walks and join a hiking club.

Mary shared all of this information with me in a chance meeting that we had recently. I think Mary is similar to many people in her concerns, health history, and desire to choose walking as a way to attain physical activity. Staying on the last point, walking is an attractive modality for being active due of its simplicity (do you have shoes and an open piece of land?) and low intensity.

So what benefits does walking offer? What can Mary expect to attain with her walking program? Let's discuss.

Blood Pressure

Walking improves systolic blood pressure (the top number). In one study, men and women, with an average age of 47, performed three 10-minute walks over three hours [1]. Immediately after each walk, systolic blood pressure decreased about 3-4 mmHg. These men and women had healthy blood pressures to start with. Individuals with hypertension (high blood pressure) are likely to experience greater gains as they have more room to improve.

Blood pressure is unique in that it does not require a high exercise intensity to improve [2]. This is why walking is effective for reducing blood pressure. Not only does walking improve systolic blood pressure, but the improvement can last for about 22 hours following a 30-minute walk [3].

Insulin Sensitivity

After breaking down carbohydrates and protein, glucose is released from the small intestine into the blood stream. Insulin's task is to taxi the glucose from the blood to the desired locations (liver and muscle cells). When the liver and muscle cells are efficient in receiving glucose from insulin, a person is said to be in a state of "insulin sensitivity." Why is this important? Insulin sensitivity helps regulate blood glucose and prevents an individual from becoming diabetic. 

Insulin sensitivity is another health measure that improves with physical activity, regardless of the activity's intensity. In fact, the greater the volume of exercise, the greater the insulin sensitivity benefit is--regardless of an activity's intensity. This was demonstrated in an eight month study where 40-65 year-old men and women performed one of three weekly routines: walking 12 miles, jogging 12 miles, or jogging 20 miles [4]. All groups improved insulin sensitivity, but the walking group experienced the greatest change. Why? While all groups spent at least 113 minutes exercising each week, the walking group required the most time to complete their weekly goal (an average of 176 minutes per week).  

Bone Density

If Mary sticks to her walking and hiking routine without adding any additional exercise, it's unlikely that she'll improve her bone density. While walking does not increase bone density, there is evidence that suggests brisk walking is an effective way to slow the age-related loss of bone density [5].

Weight Loss

In regards to weight, let's go back to the eight month study where men and women walked 12 miles per week for a total weekly exercise time of 176 minutes [4]. The men and women in this study were overweight or obese to start with (based on body mass index data), so they were more likely to lose weight than Mary, who is not carrying an excessive amount of weight. Unfortunately, eight months of walking provided no weight loss, despite the other health improvements that did occur.

For more on weight's connection to running, let's examine the results of a longitudinal study. Longitudinal studies measure participants at the start and end of a specific period of time. These studies look for associations but do not provide a definitive cause-effect relationship as they lack complete control of other factors. A 15-year longitudinal study looked at the quantity of walking and its connection to weight gain with about 5,000 men and women who were between 18-30 years old at the start [6]. Over the course of the study, the average yearly weight gain was about two pounds per person. The participants in the highest quartile of walking did gain about 17 pounds less than the lowest quartile, but all quartiles gained weight. The researchers calculated that every 33 miles walked was associated with one fewer OUNCE of gained weight.

Closing Thoughts

Walking is one of my favorite physical activities. It's not only simple, but I use it as an excuse to spend time outdoors and attain vitamin D on sunny days. However, walking by itself is not comprehensive enough to address many important health matters and does not reverse the effects of age on bone density, muscle mass, and strength. Walking does improve blood pressure and insulin sensitivity, but walks need to occur frequently to sustain those changes.

In my opinion, walking serves as a great compliment to strength training. Strength training improves muscle size, strength, bone density, and also provides benefits for various health markers (blood pressure, blood glucose, etc.). Strength training is effective in small, infrequent, and intense doses. Walking addresses those health measures that require more volume. Walking is optimal in frequent doses, and the larger the dose is, the greater the benefit received.

Mary did mention that a local gym--equipped with strength training machines and certified personal trainers--provides free memberships for seniors. She may take advantage of the resource to compliment her walking and hiking. I hope she does.

On a separate note, I hope you are having a wonderful holiday season. Thank you for following Health-Actualization in 2012. I always enjoy receiving your feedback and hope that you have found H-A helpful in improving your own health and habits.

2013 is a great time to be assertive in the pursuits of your goals, dreams, and desires. Happy New Year!


Steve Parker, M.D. said...

Thanks for this summary, Sean. I hope 2013 is a great year for you.


Dr. Sean Preuss said...


Thank you. I hope 2013 is treating you well so far. I'm enjoying your blog posts, btw.