Reference
Peterman JE, Morris KL, Kram R, Byrnes WC. Pedelecs as a physically active transportation mode. Eur J Appl Physiol. 2016;116(8):1565-1573.
Design
Open, single arm study
Objective
To determine if use of pedelectric bicycles for real-world commuting improves cardiometabolic risk factors
Participants
Twenty sedentary individuals (14 female, 6 male) who did not perform regular exercise and commuted to work by car and/or public transit participated in the study. Participants engaged in less than 150 minutes of exercise per week (prior to study start) and were employed in occupations that do not require significant physical activity. The average age was 41.5 years (range 22-55 years).
Interventions
Participants were supplied with 1 of 2 models of pedelectric bicycles (either a Trek T80+ or a 2013 E-Motion City Wave) and were instructed to commute using the supplied bicycles for at least 3 days per week, for a minimum total of 40 minutes per day on each of these days. They were free to ride the bicycles as much as they liked for additional commutes, errands, or pleasure. Participants wore heart rate monitors and GPS devices whenever they rode the bicycles.
Outcome Measures
Pre- and post-intervention evaluations and physiologic testing included a medical history, physical examination, dual-energy X-ray absorptiometry (DEXA) bone scan, graded exercise testing (GXT) on a cycling ergometer, maximum heart rate, and resting blood pressure. Respiratory gas exchange and energy expenditure were measured along with heart rate and maximum oxygen consumption during exercise testing. Blood samples were obtained to assess levels of cholesterol, triglycerides, glucose (fasting and 2-hour post glucose), and insulin. Fasting plasma glucose and insulin levels were used to calculate homeostatic model assessment (HOMA), a measure of insulin sensitivity.
Key Findings
During the 4-week intervention participants rode an average of 318 kilometers, averaging 4.9 ± 1.2 metabolic equivalents (METs) when riding. This activity significantly improved their 2-hour glucose tolerance test and their power output. There were nonsignificant trends toward improved mean arterial blood pressure and decreased fat mass.
Practice Implications
As the impact of a sedentary lifestyle on health becomes more apparent, the value of even incremental increases in physical activity also becomes clearer. This study demonstrates that using an electrically assisted bicycle to commute to work for even 1 month has measurable health benefits.
While electric bicycles remain relatively rare in our country, they have become a phenomenon in much of the rest of the world. Sales in China increased during the 12 years from 2000 to 2012 from 300,000 units per year to 30 million. The vast majority—95%—of these bikes remain in Asia. At this point only a tiny fraction of the bikes manufactured (0.5%) reach North America. Nearly 4% reach Europe; over 1 million electric bikes were sold in Europe in 2012. In Germany over 6,000 electric bikes have been provided to postal employees.1 Sales in Europe are increasing by about 30% per year. The United States lags behind on adoption of the electric bike but the assumption is that we will soon follow these international trends.1
While electric bicycles remain relatively rare in our country, they have become a phenomenon in much of the rest of the world.
Electric bikes vary in the way the electric assist is activated to make pedaling easier. The main division is whether they use a throttle or a pedal assist. Throttle-activated assist is similar to how a motorcycle or scooter works. Activation of the throttle engages a motor to provide power and propel the bike forward.
In contrast, pedal assist bicycles, referred to a pedelecs, provide power only when the rider is pedaling.2 The participants in this study all used pedelec bikes. The riders had to pedal in order to activate assistance from the electric function to propel the bike.
The reasons that these bikes are popular in developing countries are obvious. Pedelecs are inexpensive, selling for less than 200 US dollars in China. The models sold in the developing world are typically compact; their frames fold in half for storage and they use small tires.
In 2009 Monique Simons from the Netherlands suggested that pedelec bikes might serve “…as a novel tool for meeting the physical activity guidelines in terms of intensity.” She tested 12 active adults riding various types of bicycles on a track course while wearing portable gas-analyzing equipment. Some of the bikes had electric power assist while others did not. Obviously it took less effort to pedal the pedelec bikes but Simons concluded that riding any of the bikes provided a level of exercise intensity “… sufficiently high to contribute to the physical activity guidelines for moderate-intensity health-enhancing physical activity for adults…”3,4
In 2012 French physiologists reported that riders of pedelec bikes were confused by the experience; their perceived exertion was significantly less than their actual exertion. In other words, they were expending more energy than they thought. The authors concluded that “by reducing the perceived sensation of effort while maintaining a sufficiently high energy expenditure, the electrically assisted bicycle has a great potential to promote physical activity in industrialized societies.”5
This current study is notable in part because it demonstrates significant improvements in health status over a short period with only moderate use of these pedelec bikes, but also because of the study’s location, Boulder, Colorado. Boulder is the home of many elite athletes, including some of the top bicycle racers in the United States. This has influenced local culture so that a high percentage of the city’s population consists of ultra-fit athletes. Colorado has the fewest overweight people of any state, but here in Colorado, Boulder stands out as having a population that is super-fit. The number of bicycles in Boulder nearly equals the city’s population.6 This reader found himself impressed that Peterman et al could even find 20 sedentary individuals in the city to participate in their study.
Using pedelec bikes appears to overcome some of the deterrents to bicycle commuting, in particular long distances and difficult hills, reducing the level of exertion so that one can commute without necessarily needing to shower and change on arrival. The participants did not experience increased fatigue to the degree that they reduced or curtailed other physical activities. Participants were able to “…incorporate physical activity into their day without requiring them to set aside time specifically for exercise and thus limit some of the barriers associated with meeting the physical activity recommendations…”
One downside of these pedelec bikes is that it is easy to go fast. While power assist speeds are limited to 25 km/h, Dutch research suggests riders of pedelec bikes are more likely to be treated for injuries sustained in accidents than riders of traditional bikes.7 A second downside is cost. While inexpensive in Asia, these pedelecs sell for significantly higher prices in the United States. Time, increasing popularity, and market competition may change that.
What doesn’t get reported in the research is that riding these bikes is apparently fun, even described as “a blast.” In the words of one of the study authors, William Byrnes, “It’s exercise that is fun.”8
It might serve our patients if we, their naturopathic physicians, were to be early adopters of this technology and were to model commuting to work by pedelec bike.
