Walking, the simplest exercise for health
Walking away from disease
Most of us know that exercise is key for improving health and for prevention of chronic diseases. What some of us may not be aware of, is that walking qualifies as an effective deterrent as well as an immediate remedy for diabetes type 2 and, can prolong life.
How much do we need to walk to reduce our risk for developing diabetes type 2? Numerous studies have found that walking for at least 30 minutes a day can lower a person’s risk of developing diabetes type 2, and the greater the walk, the lower the risk.
One study (1) assessed the physical activity of over 70.000 women and their subsequent risk of developing diabetes type 2. These women were part of the Nurse’s Health study cohort, an observational study that described the medical history and health practices for over 120,000 nurses living in 11 states in the United States (U.S.). At the beginning of the study, none of the group had diabetes type 2, cardiovascular disease or cancer and after 8 years of follow up, a total of 1419 cases of diabetes were confirmed. The results showed that those who undertook physical activity had substantial reductions in their risk of diabetes type 2 compared to those who did not exercise and the more they worked out, the more they reduced their risk. Most of the women who undertook any physical activity chose walking, and when the total energy output was the same from walking as it was from more vigorous exercise, the risk of type 2 diabetes was similar. This suggests that if you walk long enough, this can be just as beneficial as more vigorous forms of exercise. Indeed, walking may a better option, as it is safer, less injury-related, more convenient and more easily achievable.
Another study (2) assessed the effects of walking on the risk reduction of developing type 2 diabetes in a group of people who have a high prevalence of obesity, diabetes type 2, insulin resistance and several other heart disease risk factors. 1826 of these people from 13 American Indian communities in the U.S. were followed up for 5 years. None of them had cardiovascular disease or diabetes type 2 at the start of the study, although 178 people were prediabetic. Each person was given a pedometer to attach to their hip, during their waking hours for one week and physical activity was measured as the number of steps taken per day. The results found that people who took at least 3500 steps a day had a 29 % lower risk of developing diabetes compared to those who were more sedentary (generally 2000 steps is equal to one mile). This study shows that walking can be an effective tool in prevention particularly in those who are more endemically prone to diabetes and obesity.
Several other studies suggest that if you have diabetes type 2, walking acts as a remedy and results in a plethora of health benefits. One recent study (3) examined the impact on health of increased physical activity in previously sedentary diabetes type 2 patients. 179 such patients were followed up for 2 years, and underwent a counseling program to encourage them to increase their physical activity to at least 10 METS h/week, where METS is the metabolic equivalent, and measures the physical activity in multiples of resting energy expenditure. For example, 2 METs/hour has the energy expenditure of double the resting metabolic rate.
The patients were divided into six groups depending on their change in increments in energy expenditure. Again, walking was the activity of choice for most of the patients. They found that increasing walking to achieve more than 10 MET h per week, was the minimum increase in physical activity needed to achieve health benefits. In this study, 69 % of patients had an increase of at least 11 MET h/week, which is equivalent to around 30 minutes or more of walking. The health benefits continued to increase as the expenditure levels rose to 21 to 30 MET h/week. These results led the researchers to recommend 27 MET h/week or around a 5 K daily walk or 45 minutes per day at a pace of 4 miles per hour. The health benefits were seen in people with different ages, sex, races, body mass index, diabetes duration, diseases, and physical limitations.
Health benefits
What were the health benefits achieved? These included a reduction in: Body weight, BMI), waist circumference, fasting plasma glucose (blood glucose levels while fasting), HBA1c (measurement of glucose in blood-see diagram), blood pressure, heart rate, total low density lipoprotein (the detrimental cholesterol), triglycerides (types of fats associated with prediabetic conditions), and cardiovascular risk. There was also an increase in high-density lipoprotein (the beneficial cholesterol). Last but not least, financial costs were reduced, as the patient’s health improved, they spent less on trying to rectify ill health. This study suggests that walking not only controls glucose levels, but also reduces cardiovascular events and therefore reduces mortality.
Indeed, numerous research has shown that walking prolongs your life. One study by Gregg, 2003 (4), examined the association between walking and the risk for mortality form cardiovascular disease or all cause mortality (annual number of deaths overall).
A diverse group of 2896 adult Americans with diabetes type 2 were followed up for 8 years, for their physical activity and associated mortality. The results of this study showed that walking was associated with lower mortality rates, and the higher levels of walking and total physical activity were associated with a lower incidence of all cause and cardiovascular disease mortality. The greatest risk reduction was in those walking 3 to 3.9 hours per week, and those who walked at least 2 hours per week still had a 39 % lower all cause mortality rate. The results suggested that for every 61 people who could be persuaded to walk this amount, one death per year would be preventable.
These confirmed previous studies including one carried out on the aforementioned nurses health cohort (5), which showed that walking and vigorous activity were also associated with reduced rates of cardiovascular events, coronorary heart disease events and strokes, in diabetic women aged 30 to 55 years.
In people with diabetes type 2, there is abnormal lipid or fat storage and oxidations, processes involved in fat metabolism. A further benefit of walking is that it induces enhancement of resting lipid or fat oxidation, which helps with fat metabolism (6). Walking also decreases adipose or fat tissue mass, encourages weight loss, and makes us leaner, which leads to greater insulin sensitivity or effectiveness of insulin.
To walk before or after a meal
When should this monumentally beneficial walk take place? Studies have shown that the timing of exercise affects the gycemic effect, or impact on the glucose levels, of the food you eat. If you have diabetes type 2, taking a walk after a meal may actually be better than walking before a meal. One study (7) found that fasting men with diabetes type 2, who underwent aerobic exercise before a meal, led to a minimal impact on blood glucose levels and when these men worked out two hours after a meal, blood glucose levels were more reduced. Another study found that (8) that 20 minutes of walking shortly after meal consumption in the evening led to lower plasma glucose levels at the end of exercise compared to values when subjects who had walked pre dinner. Walking helps control post prandial or post meal glycemia, or high blood glucose levels that follow after a meal. This is important for diabetics as post-prandial hyperglycemia (post meal high blood glucose levels) poses a cardiovascular risk, and can lead to diabetic complications such as eye damage, kidney problems and foot ulcers.
The likely mechanisms of these effects of post meal walking may be as follows; When the meal is ingested, blood glucose levels rise, and as a result insulin is released and this lowers the post meal glycemic responses. Insulin works by binding to its receptors in muscle and adipose tissues, which leads to an increase in GLUT 2 molecules, which are glucose transport proteins that help transport glucose from our blood to our cells (see diagram). In addition walking stimulates muscle contractions, which also stimulates glucose transport into muscle cells in the absence of insulin. So glucose uptake is achieved by both insulin secretion post meal, and the muscle contraction during exercise. The additive effect serves to have a greater effect on reducing blood glucose post meal than pre meal.
People with diabetes type 2 may have undetected complications such as micro vascular or macro vascular disease (disease in the small or large blood vessels), which may lead to adverse health events with more vigorous exercise. For such reasons, physicians are reluctant to recommend vigorous exercise to these patients. This is all the more reason to take up walking if you have diabetes type 2 as it is a safe and effective exercise.
If a 45-minute walk seems daunting, then you can break it up during the day, as it is the summation of the number of steps taken per day that counts. This further commends walking as a preferred daily exercise, for people with or without diabetes type 2, because the benefits it encompasses, are simply too good to miss. It is worth keeping in mind that small steps can add up to large benefits and with time, both the steps and benefits will certainly pay off.
What is HbA1c?
Red blood cells contain haemoglobin. Glucose attached to the haemoglobin to make a ‘glycosylated haemoglobin’ molecule, called haemoglobin A1C or HbA1C. The more glucose in the blood, the more haemoglobin A1C or HbA1C will be present in the blood.
http://medweb.bham.ac.uk/easdec/prevention/images/hba1c.gif image of blood cell combining with glucose.
Walking references, diagrams, terms and studies
References
1. Walking compared with vigorous physical activity and risk of type 2 diabetes in women. JAMA, 1999; 282 (15): 1433–1439. Frank B. Hu et al.
2. Modest levels of physical activity are associated with a lower incidence of diabetes in a population with a high rate of obesity. Diabetes Care. 2012 vol. 35 no. 8 1743–1745. Fretts A. M. et al.
3. Long-term impact of different amounts of physical activity on type 2 diabetes. Diabetes Care. June 2005, Vol 28, no. 6,. Di Loreto C, et al.
4. Relationship of walking to mortality among U.S. adults with diabetes. Arch Intern Med 2003, vol 163, June 23,. Gregg E. W., et al.
5. Physical activity and risk of stroke in women. JAMA. June 2000, vol 283, no. 22, 2961–2967. Hu B., et al.
6. Increased daily walking improves lipid oxidation without changes in mitochondrial function in type 2 diabetes. Diabetes Care. 2008 Aug; 31(8):1644–9. Trenell MI, Hollingsworth KG, Lim EL, Taylor R.
7. Postprandial walking is better for lowering the glycemic effect of dinner than pre dinner exercise in type 2 individuals. J Am Med Dir Assoc. 2009, Jul: 10 (6):394–7.
Colberg SR., et al.
Images and Diagrams to check out
Diagram 1.
HbA1c : Glucose attaches to the haemoglobin in red blood cells to make a ‘glycosylated haemoglobin’ molecule, called haemoglobin A1C or HbA1C. This is used as a measure of glucose in the blood. (very simple diagram/animation at the link below)http://medweb.bham.ac.uk/ea
Diagram 2.
Images from the You Tube video “insulin and glucose and You”, description below;
Insulin allows blood glucose to enter the cells of the muscles, adipose tissue and liver to give us energy. Insulin binds to the receptors on the cells (take image from animation at 0.57–1.02 seconds) and signals the cells to activate glucose transporters, GLUT 4 molecules (take image from 1.02–1.06 seconds). This allows glucose to pass through the cell walls.
Walking terms
# 1. 2000 steps averages around 1 mile
# 2. Blood glucose levels while fasting
#3. Measurement of glucose in blood-see diagram 1
#4. Types of fats associated with prediabetic conditions
#5. Post-meal high blood glucose levels