Do You Get the Same Results?
Guest blog by John Davis (RunnersConnect)
Nothing is more jarring than cruising along during a run at a solid pace, until you realize the world is not with you in your rhythm, and you have to suddenly come to a stop at a busy intersection to wait for the lights to change.
If you live in the city, or near a road with heavy traffic, this might happen to you a lot.
You may wonder if interruptions like this counterproductive for your training. Is a three or four-minute break in the middle of a run interfering with the benefits of your workout?
This question is relevant even to runners lucky enough to have routes that don’t have stoplights on them. What about bathroom breaks? We have all needed to go to the bathroom while running before.
Or what if you’re a newer running using a broken-up walk/jog training program for your first marathon? Read our post Why Running Slow Doesn’t Matter.
Continuous running vs. stopping and starting
Surprisingly, there has not been any direct research on the question of the effects of very short breaks in a run versus completely continuous running, so we will have to get a bit creative about how we go about searching for answers.
Most research on continuous versus intermittent training in athletes is focused on comparing the relative value of high intensity running during the “on” periods, and walking or standing recovery during the “off” periods—essentially, an interval workout.
Several studies have compared interval-style training to continuous running,but these are not a helpful analogy to taking short breaks during a regular run, since the intensity is not going to be drastically different before and after you interrupt your run.
There is some research on breaking up exercise into several smaller chunks of equal intensity, instead of one continuous block. These studies, however, are focused on improving fitness in overweight or sedentary adults, not athletes. Regardless, they are worth a look.
A 2006 study of fifty sedentary adults in Hong Kong analyzed fitness gains from one daily session of 30min of continuous activity compared five six-minute blocks of activity interspersed throughout the day.1
The study found that VO2 max improved by about the same amount in each group, with the authors writing that the benefits of intermittent exercise of equivalent energy expenditure were similar to the benefits of continuous exercise.
Whether this carries over to higher level training in fit athletes is unclear, but it’s at least a good sign.
Another study, published in 2008 by researchers at the University of Virginia, investigated the effects of a 30min bout of exercise or three 10min bouts at the same intensity on the levels of growth hormone in the blood during the 24-hour period following exercise.2
Though the study focused on obese individuals, there was a fifteen-person control group which had a healthy weight, and within this group, both the 30min and the 3x10min exercise sessions resulted in marked increases in growth hormone in the blood during the day following exercise sessions—a good thing for performance gains—but no significant differences between the two.
We can interpret this to mean that the hormonal benefits of training persist regardless of short (or even longer) breaks in your run, as long as you accumulate the same total amount of running. Check out our post about Understanding How Metabolism works to unlock the mystery of Weight loss for more about hormones.
Heart rate as an indicator of effect
A more obvious factor to consider is heart rate. As soon as you stop running, your heart rate drops.
How fast your heart rate “recovers,” or returns to its resting level once you stop, is dependent on your level of fitness: the fitter you are, the quicker you are able to decrease your heart rate when you stop running when compared to people who are out-of-shape.
This ability is such a good indicator of overall fitness that it’s been found to be a protective factor from sudden death!3
Being able to quickly bring down your heart rate is great for your lifespan, but it does mean that your heart rate will have dropped by 40 or more beats per minute even after just one minute of rest.
If there is a benefit to maintaining a consistently elevated heart rate—and this is an uncertain proposition—you would need your run to be more or less totally continuous, with no stopping at all. On the other hand, the dependence of heart rate recovery on fitness means that newer runners who are not very fit will still maintain a fairly high heart rate during a one or two-minute walk-break.
Plan your route
Real-world experience tells us it can’t be that critical to run nonstop during regular runs: plenty of very fast runners live and train in places like Boston or New York City, and are prepared that one of the downsides of living in the city is that they will need to stop at intersections often.
The occasions where you would like to prioritize uninterrupted continuous runs are your race-specific workouts: if you are doing a ten-mile run at your goal marathon pace, for example, you should try to set it up on a route that won’t have any interruptions.
Even if there’s uncertainty over the physiological benefits, you should keep your race-specific workouts as similar to racing conditions as possible.
From the limited research available, the evidence indicates that short interruptions to your run, whether it’s a stoplight, a bathroom break, or a planned walking break, do not have any major impact on the physiological benefits of training.
Fitness gains, at least in sedentary people, appear to be the same when you compare intermittent versus continuous exercise, and growth hormone levels respond similarly regardless of how you structure your daily exercise.
The big unanswered question is heart rate: is there any additional benefit to your cardiovascular fitness by keeping your heart rate elevated continuously for a long time?
It would require a very well-designed experiment to test this, and the effects, if any, are likely to be small.
In general, you should not fret if you have to stop at a light or use the bathroom for a few minutes. Though research to date is limited, it indicates that you’ll still get the same benefits as long as your total duration of running is the same.
Do you get frustrated stopping during your run? Do you feel it is better psychologically to break up the run, or does it mess up your rhythm?