Doctor, Heal Thyself: Part 2
A heart-to-heart about exercise
KIMBERLY K. REED, O.D., F.A.A.O.
In 2013, the American Heart Association released a cardiovascular risk calculator (CV Risk Calculator). Specifically, it enables you to input your total and HDL cholesterol, systolic blood pressure and history of diabetes and smoking, among other demographic information, so you can view a graphic display of your 10-year and lifetime risk for atherosclerotic cardiovascular disease (including coronary heart disease death, nonfatal myocardial infarction or stroke). (To access the CV Risk Calculator, visit http://bit.ly/IWXTJp.)
One of the most powerful drivers of this risk prediction tool is the systolic blood pressure value. The strongest associated life-style factors for elevated blood pressure are obesity and lack of physical exercise, which are, in turn, intricately associated with each other.
It stands to reason, then, that one way to reduce cardiovascular event risk is to integrate a physical activity program, if you don’t already routinely exercise in a heart-smart way.
Here, I discuss the steps to accomplish this.
1 Undergo a physical exam
As per Part 1 of this series (June 2014 OM), schedule a physical exam, and inform your healthcare practitioner that you wish to begin exercise, or that you want to increase the frequency and/or intensity of an existing program. The results of a thorough physical exam will enable you determine the second step.
2 Choose your workout
There are two types of exercise from which you can select:
• Continuous moderate exercise (CME). Also known as continuous aerobic training, these typically 30+ minute sessions are designed to keep the heart rate at approximately 70% of maximum,* often referred to as the “fat burning” zone. Examples of CME: jogging, riding a stationary bike or using an elliptical machine at a steady pace for 30 or more minutes, four to five times weekly.
• High intensity interval training (HIIT). HIIT can take many forms, but essentially includes short periods of all-out effort (90% and higher of maximum heart rate) interspersed with recovery periods. Protocols vary, ranging from a 20-second all-out, full-intensity effort with 10 seconds of recovery repeated eight times for a total of four minutes, to 30-minute sessions with longer high-intensity and recovery periods. The choices for HIIT training include: group classes, guided running, cycling and swimming workout plans, instructional videos and more. If you’re investigating your options, look for “high intensity” and “heart rate training” in the description of the workout.
Evidence continues to mount that CME is less effective than HIIT in improving aerobic fitness and reducing CV risk. A preponderance of studies show that HIIT is more effective than CME in reducing subcutaneous, abdominal and total body fat, blood pressure and total and LDL cholesterol while increasing HDL cholesterol. In addition, it has been shown superior in improving VO2 max (a measure of oxygen utilization), insulin sensitivity and insulin signaling, endothelial function, left ventricular myocardial function and glucose tolerance in Type 2 DM. Finally, HIIT has been shown more effective than CME in increasing mitochondrial capacity and burning more calories and increasing post-exercise fat burn (“after burn” effect).
Moreover, HIIT is considered “very safe” in a controlled environment. Many of the studies yielding these beneficial results were done with fairly sick patients (very high BMI, S/P stroke, MI or other cardiovascular event), and the exercise sessions were conducted under direct medical supervision.
3 Get moving
This is the most difficult step — actually doing the workout. Pick one of the aforementioned activities, choose a specific exercise, and don’t do it half-heartedly. OM
*Maximum heart rate can be ESTIMATED by subtracting your age from 220. This estimate can be significantly off target, however. The specific measurement is offered at many fitness facilities.
Optometric Management, Volume: 49 , Issue: August 2014, page(s): 44, 45