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Exercise Made Just For You

A group of young adults participate in an aerobic jogging workout.
Jessica Collins conducts aerobic workouts for her research, similar to what's pictured above.
Photo by Danielle Cerullo

Have you ever walked into a busy gym and immediately felt overwhelmed by the sheer number of machines? How do you know which workout will benefit you the most? It may be tempting to turn around, walk out the door, and head back home to bed. Luckily, with the help of student wellness adjunct professor Jessica Collins, BYU students discovered a more effective way to personalize the prescription of exercise.

Researchers and coaches have been perplexed for years as to why people receive varying benefits from the same kind of exercise. For example, two people could run at the same percentage of their max heart rate for the same distance through multiple months, and yet, one person could only increase their endurance a mere 4%-12% while the other person could increase their endurance by 40%-60%.

Collins (MS ‘21) approached the issue from a physiological perspective. She recognized that the body’s way of adapting to different kinds of exercise is in levels above and below the physiological threshold known as “critical power.” Critical power is the highest power/intensity of exercise you can sustain for a long period of time.

Collins hypothesized that the effectiveness of a workout is determined by how far above or below critical power it is.

“We wanted to test out two common aerobic exercise programs because they’re what people are doing see exactly how these programs influenced critical power,” said Collins. “We programmed the exercises so our subjects could reach their maximum power, and we found a lot of variability. The people who were doing the high intervals were working at the same percentage of their VO2 max — the maximum amount of oxygen consumed during exercise — but had very different results.”

Collins’ research took place over two years. 22 subjects participated and each individual completed eight weeks of workouts. They were each assigned two different types of exercise training at fixed percentages of their maximum aerobic ability or “VO2 max.” Collins and her lab were surprised to find that both training programs increased critical power.

At the end of her study, Collins found that a participant’s growth was based on where the exercise fell along their critical power. “Because critical power plays such a big role, maybe instead of prescribing our workouts based on VO2 max, we should base it off of critical power because that makes our workout so much more personal. Critical power could help an individual see results faster,” Collins said.

Collins said she felt extremely lucky for this to be the big study for her master's thesis. Not only did she love the topic, but working with real people meant a lot to her. “I was able to develop a relationship with my volunteers and encourage them to keep pushing through the hard exercises so they could see improvement at the end of the study,” Collins said.

Collins’ study could be life changing for many people. By creating exercise plans based on an individual’s placement on the critical power threshold, one could see their endurance increase and be more confident in the way they work out.

Along with being an adjunct teacher, Collins has been teaching cycling classes for the last year as a part of BYU’s student wellness program. “I get to apply the research and our findings with those classes, and get to explain the science to my students to help them better understand how to make a more personalized workout on their own,” Collins said. “I enjoy helping them feel more empowered and confident.”