Walking is a simple, cost-free form of exercise that benefits physical, social, and mental health in many ways. Several clinical trials have shown that walking regularly is associated with a lower risk for cardiovascular events and all-cause mortality, and having a higher daily step count is linked to a decreased risk for premature death.
Walking and Diabetes
In recent years, the link between walking speed and the risk for multiple health problems has sparked keen interest. Data suggest that a faster walking pace may have a greater physiological response and may be associated with more favorable health advantages than a slow walking pace. A previous meta-analysis of eight cohort studies suggested that individuals in the fastest walking-pace category (median = 5.6 km/h) had a 44% lower risk for stroke than those in the slowest walking-pace category (median = 1.6 km/h). The risk for the former decreased by 13% for every 1 km/h increment in baseline walking pace.
Type 2 diabetes (T2D) is one of the most common metabolic diseases in the world. People with this type of diabetes have an increased risk for microvascular and macrovascular complications and a shorter life expectancy. Approximately 537 million adults are estimated to be living with diabetes worldwide, and this number is expected to reach 783 million by 2045.
Physical activity is an essential component of T2D prevention programs and can favorably affect blood sugar control. A meta-analysis of cohort studies showed that being physically active was associated with a 35% reduction in the risk of acquiring T2D in the general population, and regular walking was associated with a 15% reduction in the risk of developing T2D.
However, no studies have investigated the link between different walking speeds and the risk for T2D. A team from the Research Center at the Semnan University of Medical Sciences in Iran carried out a systematic review of the association between walking speed and the risk of developing T2D in adults; this review was published in the British Journal of Sports Medicine.
10 Cohort Studies
This systematic review used publications (1999-2022) available in the usual data sources (PubMed, Scopus, CENTRAL, and Web of Science). Random-effects meta-analyses were used to calculate relative risk (RR) and risk difference (RD) based on different walking speeds. The researchers rated the credibility of subgroup differences and the certainty of evidence using the Instrument to assess the Credibility of Effect Modification ANalyses (ICEMAN) and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) tools, respectively.
Of the 508,121 potential participants, 18,410 adults from 10 prospective cohort studies conducted in the United States, Japan, and the United Kingdom were deemed eligible. The proportion of women was between 52% and 73%, depending on the cohort. Follow-up duration varied from 3 to 11.1 years (median, 8 years).
Five cohort studies measured walking speed using stopwatch testing, while the other five used self-assessed questionnaires. To define cases of T2D, seven studies used objective methods such as blood glucose measurement or linkage with medical records, and in three cohorts, self-assessment questionnaires were used (these were checked against patient records). All studies controlled age, sex, and tobacco consumption in the multivariate analyses, and some controlled just alcohol consumption, blood pressure, total physical activity volume, body mass index, time spent walking or daily step count, and a family history of diabetes.
The Right Speed
The authors first categorized walking speed into four prespecified levels: Easy or casual (< 2 mph or 3.2 km/h), average or normal (2-3 mph or 3.2-4.8 km/h), fairly brisk (3-4 mph or 4.8-6.4 km/h), and very brisk or brisk/striding (> 4 mph or > 6.4 km/h).
Four cohort studies with 6520 cases of T2D among 160,321 participants reported information on average or normal walking. Participants with average or normal walking were at a 15% lower risk for T2D than those with easy or casual walking (RR = 0.85 [95% CI, 0.70-1.00]; RD = 0.86 [1.72-0]). Ten cohort studies with 18,410 cases among 508,121 participants reported information on fairly brisk walking. Those with fairly brisk walking were at a 24% lower risk for T2D than those with easy or casual walking (RR = 0.76 [0.65-0.87]; I2 = 90%; RD = 1.38 [2.01-0.75]).
There was no significant or credible subgroup difference by adjustment for the total physical activity or time spent walking per day. The dose-response analysis suggested that the risk for T2D decreased significantly at a walking speed of 4 km/h and above.
Study Limitations
This meta-analysis has strengths that may increase the generalizability of its results. The researchers included cohort studies, which allowed them to consider the temporal sequence of exposure and outcome. Cohort studies are less affected by recall and selection biases compared with retrospective case–control studies, which increase the likelihood of causality. The researchers also assessed the credibility of subgroup differences using the recently developed ICEMAN tool, calculated both relative and absolute risks, and rated the certainty of evidence using the GRADE approach.
Some shortcomings must be considered. Most of the studies included in the present review were rated as having a serious risk for bias, with the most important biases resulting from inadequate adjustment for potential confounders and the methods used for walking speed assessment and diagnosis of T2D. In addition, the findings could have been subject to reverse causality bias because participants with faster walking speed are more likely to perform more physical activity and have better cardiorespiratory fitness, greater muscle mass, and better health status. However, the subgroup analyses of fairly brisk and brisk/striding walking indicated that there were no significant subgroup differences by follow-up duration and that the significant inverse associations remained stable in the subgroup of cohort studies with a follow-up duration of > 10 years.
The authors concluded that "the present meta-analysis of cohort studies suggested that fairly brisk and brisk/striding walking, independent of the total volume of physical activity or time spent walking per day, may be associated with a lower risk of T2D in adults. While current strategies to increase total walking time are beneficial, it may also be reasonable to encourage people to walk at faster speeds to further increase the health benefits of walking."
This article was translated from JIM, which is part of the Medscape Professional Network.
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