January 6, 2022 – In recent years, there have been efforts to encourage doctors to prescribe exercise as medicine, telling their patients how often, how long and the way intensely they need to exercise to enhance their health.
A brand new study from Brigham Young University suggests that doctors could take this initiative to the following level by prescribing exercise plans that result in a selected health end result, reminiscent of lowering blood pressure or shedding weight.
“The results of this and other studies suggest that we should be able to prescribe exercise more consistently and precisely like medicine,” says lead study creator Jayson Gifford, PhD, professor of exercise science at BYU.
These training recommendations can be tailored to patients and based on a largely ignored fitness measure called critical power or maximum regular state – that's, the utmost speed you'll be able to achieve while maintaining a pace you'll be able to sustain over a protracted time period.
By designing workouts based on critical power slightly than the more commonly used VO2max (maximum effort), we will more accurately predict health outcomes, just as we will in medicine, the researchers say. in the Journal of Applied Physiology.
“We have known for centuries that exercise is an important component of a healthy and long life,” says Dr. Jordan Metzl, a sports medicine specialist on the Hospital for Special Surgery in New York and creator of The exercise cure“But it is only in the last 70 years that we have recognized the medical value of exercise.”
Metzl, who was not involved within the study, helped develop an annual seminar at Cornell Medical School that teaches medical students ways to prescribe exercise beyond the usual half-hour per day advice. Still, doctors and other health professionals often have difficulty prescribing exercises for the prevention or treatment of diseases. And a current study from Oxford found that doctors who give advice on weight reduction The information is often vague and difficult for patients to use.
“Exercise is one of the safest and most effective forms of health care,” says Metzl. “We need to get the medical community to prescribe exercise to their patients.”
This study suggests that specializing in critical performance could also be key to achieving this goal.
What the research revealed
In the study, 22 adults accomplished either moderate intensity training or high intensity interval training (HIIT) for 8 weeks. The intensity levels laid out in each plans were based on VO2max, meaning that study participants trained at specific percentages of their VO2max.
Both groups saw improvements in endurance, but results varied widely from individual to individual. These mixed results could also be explained by individual differences in critical performance.
“The improvement was much more strongly correlated with the percentage of critical power at which each participant performed than with the percentage of their VO2max, as exercise physiologists have assumed for years,” says lead study creator Jessica Collins, a researcher at Brigham Young University.
In addition, several subjects didn't improve their VO2max. did Experience a rise in critical performance and endurance.
“People tend to focus on VO2 max,” says Gifford. “Many may see that some people don't improve VO2 max and conclude that the training was ineffective. Personally, I believe that many potentially useful therapies have been ruled out by the almost exclusive focus on VO2 max.”
It seems that critical power varies greatly from individual to individual, even amongst individuals with similar VO2 max values.
“Let’s say you and Jessica have the same VO2max,” explains Gifford. “If you each do 70% of [your VO2 max]it might be above your maximum regular state, which might make it really hard for you. And it might be below her maximum regular state, which might make it easy for her.”
This means that each of you puts different demands on your body and this strain is the trigger for improving your fitness and endurance.
“Below critical performance, metabolic stressors are well controlled and maintained at elevated but constant levels,” says Gifford. “Above critical performance, metabolic stressors are produced so rapidly that they'll not be controlled and continually increase until they reach very high levels that result in failure.”
If you know your critical performance, you can predict how those stressors will build up, and you can tailor a training program that gives you just the right stressor “dose,” Gifford says.
Such programs could be used with rehabilitation patients recovering from a heart attack or lung disease, Gifford suggests. Or they could help older adults improve their endurance and physical performance, Collins notes.
But first, researchers must confirm these results by programming training sessions based on participants' critical performance levels and observing how much improvement results from different interventions.
How to determine your critical performance
Critical power is nothing new, but it is largely ignored by exercise physiologists and physicians because it is not easy to measure.
“People generally train based on their VO2 max or maximum heart rate, which is even less accurate,” says Gifford.
To determine people's critical performance, the study required multiple timed trials and calculated the relationship between speed/power and time, Gifford explains.
To roughly measure your critical power, however, you can use an app that measures functional threshold power (FTP). Gifford calls this the “Walmart version” of critical power. “It’s not exactly the same, but it’s close,” he says. (The app Strava has FTP and a fairly sophisticated performance analysis.)
Or skip the technique and go by feel. If you're below your critical power, “it's going to be difficult, but you'll feel such as you're on top of things,” says Gifford. Above your critical power, “your respiration and heart rate will continually increase until you fail after about 2 to quarter-hour, depending on how far above you might be.”
Still, you don't need to know your critical strength to start training, Collins notes.
“The great thing about exercise is that it's such a strong drug which you can see advantages without refining your training like that,” he says. “I might hate for this to grow to be a hindrance to exercise. The most significant thing is to do something.”