Riverdale resident A.J. Fisher publishes study on controlled breathing during exercise

Riverdale resident A.J. Fisher’s research has been published in a peer-reviewed scientific journal, marking the latest step in a yearslong effort to study how controlled breathing affects the body during exercise.

The exploratory study, published Sept. 4 in “Frontiers in Physiology,” found people exercising at a moderate pace with controlled breathing had lower blood lactate — a substance the body produces for energy that rises as exercise intensifies — than those breathing normally. Deliberately managing breath during exercise was associated with lower blood lactate and a lower average heart rate than normal breathing, even though participants reported similar levels of exertion.

Researchers also found the controlled-breathing condition resulted in lower lactate than the low-oxygen condition at the 20- and 30-minute marks, along with a lower average heart rate overall, suggesting the body was working less hard even though it didn’t feel that way.

“It’s a really big deal,” Fisher said of the publication, adding it is among the first of its kind. “I mean, I’m actually completely shocked.”

She is the study’s first author, with the research conducted in partnership with the New York Institute of Technology and financial support from American Public University, where Fisher studied exercise science.

A personal trainer and former Broadway performer, Fisher leads high-altitude yoga classes, where oxygen levels are lowered to mimic conditions at roughly 10,000 feet above sea level. At the core of the class is a controlled breathing method she developed, meant to regulate how the body responds to physical and mental strain.

Alexander Rothstein, a co-author at the New York Institute of Technology and professor of exercise physiology and biomechanics, explained that the body needs oxygen to meet the demands of physical activity. But to adapt and improve, it also needs to be challenged. The study, he said, looked at how the body responds when exercise pushes it beyond what it can comfortably handle.

The study followed 15 healthy adults who completed the same 30-minute workout during three separate laboratory visits. During one session, participants exercised normally. During another, they exercised while breathing air with 15 percent oxygen, simulating some of the effects of exercising at altitude without changing air pressure. During the third, they exercised in normal air while using a controlled-breathing technique that paired their movements with timed inhaling, longer exhaling and brief breath holds.

Researchers monitored heart rate and blood oxygen throughout each session and measured blood lactate before exercise, at 10-, 20- and 30-minute intervals and after a 10-minute recovery period.

Blood lactate levels reflect the balance between how much lactate the body produces and how much it clears and uses. Because exercise in low-oxygen conditions is usually linked to greater lactate buildup, researchers initially hypothesized both low-oxygen exercise and controlled breathing would raise lactate compared with normal exercise.

Instead, participants using controlled breathing consistently had lower concentrations, said Rothstein.

“It kind of suggested to us that oxygen saturation alone doesn’t tell us exactly how we’re responding to exercise, or I should say, how we’re producing energy for exercise,” he said.

The study grew out of an earlier pilot project Fisher and Rothstein worked on together.

That research involved fewer participants and examined a wider range of measurements. Although it was presented at an American College of Sports Medicine conference, Fisher said attempts to publish the pilot study in a peer-reviewed journal were unsuccessful, in part because of the small sample and broad number of variables being examined.

The researchers used what they learned to design the newer study around a more focused set of measurements. All 15 participants completed exercises with each of the three conditions, allowing researchers to compare each person’s physiological response across the different exercise environments.

Publication also required extensive revisions. Fisher said two peer reviewers submitted about 25 to 30 comments and questions each, prompting her to substantially rewrite the manuscript within a two-week deadline. She said she began waking around 4 a.m. to work on revisions while continuing to train clients and care for her family.

Rothstein said the review process ultimately strengthened the paper, particularly by requiring the researchers to better demonstrate that exercise workloads were comparable among the three conditions.

“Peer review suggests that you should always question everything,” Rothstein said.

The researchers cautioned that the study does not establish why controlled breathing produced lower lactate and heart rate, and it does not prove the technique improves athletic performance.

The authors said further studies are needed to examine muscle oxygenation, gas exchange, respiratory function and other possible mechanisms, as well as whether the findings hold across larger populations and different forms of exercise.