Researchers from Indiana University Bloomington and the University of Alabama at Birmingham knew that cardiorespiratory fitness – the efficiency with which the cardiorespiratory system delivers oxygen during exercise – was linked to greater bacterial diversity. However, they didn’t know whether this was caused by physical activity or body fat.
To figure this out, they worked with 37 nonmetastatic breast cancer survivors who completed conventional cancer treatment for at least a year before the actual study was conducted. The team decided to recruit this group of participants because conventional cancer treatments negatively affect cardiometabolic health, including increased body fat percentage and reduced physical fitness.
For the study, the participants completed graded exercises, so the researchers could measure their peak physical and total energy expenditures. The researchers also collected fecal samples from the participants to examine the volunteers’ gut microbiota.
The results revealed that participants who were more physically fit had more diverse bacteria in their gut compared with those who were less physically fit. The researchers also confirmed that an individual’s fitness accounted for about a quarter of the variety in bacteria. This effect was independent of body fat.
These findings suggested that intense exercise may improve overall health by promoting a better-balanced gut. The researchers concluded that their study gave insight into the association of fitness with gut microbiota diversity. However, the researchers noted that generalization of the results should be made with caution as the study population was limited to breast cancer survivors with low physical fitness and other health problems.
"Our group is actively pursuing an interventional study to determine how variation in exercise intensity can influence gut microbiota diversity under controlled-feeding conditions," said Stephen Carter, Ph.D., lead author of the study and researcher at Indiana University Bloomington, "to uncover how exercise may affect functional outcomes of gut microbiota, as well as studying how exercise prescription may be optimized to enhance health outcomes among clinical populations."
Exercises that will increase your heart rate and keep it elevated for a sustained period are the best activities for improving your cardiorespiratory fitness. These will help in strengthening your heart, enhancing blood flow, and burning fat. Here are some exercises you may want to try. (Related: A stronger heart, a healthier body: Cardiorespiratory fitness is key to lowering your risk of heart disease, advise researchers.)
Mixing these exercises will improve your fitness even more. You can walk one day, run the next, or swim one day and run the next. Doing a variety of exercises will also give your body time to recover.