Are Aerobics Good For You?
In the 1960's Dr. Kenneth Cooper published Aerobics, as the perfect way to train your heart. He thought that medium intensity aerobics done three to four times weekly was all you needed for health and longevity. These ideas have been embraced whole-heartedly by the medical and health communities. But this was never proven.
A flood of research over the past ten years has seriously undermined the concept that aerobics, or sustained light to moderate exercise has much benefit, and may even be detrimental.
Harvard researchers have now shown that short-duration, high-intensity exercise reduces the risk of heart disease by 100% more than those who practice aerobics.
A study in BMC Endocrine Disorders took 16 men and had them do four to six - 30 second all out sprints on an exercycle, alternated with four minutes of rest. They were given glucose tolerance tests before and after that measured glucose, insulin and blood fats.
The results showed improvement in blood glucose, insulin and blood fats in the two week trial. Only 7-1/2 minutes of total exercise showed improvement in all three parameters. Jogging/running have shown to only effect insulin, not blood glucose or fats in response to a glucose tolerance test.
A six week study done in 2008 compared the above regimen, 4-6 30 second all out sprints with 40-60 minutes of moderate intensity cycling 5 days per week. The results were that 10 minutes per week of actual exercise done as 30 second sprints were equivalent to 4 1/2 hours weekly of aerobics.
One of the main reasons that people give for not exercising is time. When ten minutes weekly of brief, intense intervals provides as much benefit as 4 1/2 hours of aerobics, this makes beneficial exercise much more available to people with limited time.
Research is showing that endurance exercise:
- shrinks muscle mass
- diminishes lung capacity
- increases body fat production
- no effect on growth hormone release
- increases stress hormone output
- weakens immunity
- increases inflammatory levels
- decreases the heart’s reserve capacity
- increases triglycerides and LDL cholesterol
- increases oxidation of LDL cholesterol
- causes loss of bone density
However, brief intervals of extreme exertion:
- triples blood flow to the brain, heart and lungs over moderate, sustained exercise
- increases lung volume
- decreases anxiety and stress hormones
- triggers growth hormone release
- increases metabolic rate
- increases fat burning at rest
- increases insulin sensitivity
- supports new muscle and bone growth
- builds energy reserves
- strengthens the immune system
While these concepts are controversial, the science is clear. It usually takes 10-20 years for universally accepted, yet unproven, theories to be replaced by facts, witness the slow death of the lipid hypothesis – that dietary cholesterol and fats cause heart disease (they don’t), many clinicians, trainers and exercisers will stubbornly cling to the idea that aerobics and cardio are good for you.
How does brief interval exercise effect endurance? My personal experience as a backpacker and hiker is increased endurance and less fatigue. I assume endurance is aided by increased lung and heart capacity, as well as increased strength. Doing super slow repetitions on a leg press machine have gone from 300# to 495# since doing intervals. Regarding heart health, my blood pressure has dropped 10-15 points and the occasional skipped beats or palpitations are virtually gone.
Try it yourself, using an exercycle, treadmill, or sprinting on a rebounder (my favorite) for 30 seconds, alternating with 90 seconds to 4 minutes of complete rest. Do 4-8 intervals no more than 2-3 times weekly. You will experience benefits within 1-2 weeks.
For more of the science see Dr. Al Sears’ book PACE, or google Peak 8 exercise. Also the “Exercise as Medicine” article in the Townsend Letter, November, 2011.