I’ve been pondering the nature of energy. Both Swami and Galan are experts compared to me. However, that doesn’t mean I can’t be curious and seek to satisfy said curiosity.
The reason for my curiosity is first due to a personal observation that some days I seem to work harder for less. This was made clearer when I started using the Heart Rate Monitor. For example: on Monday I had a more energetic workout then on Wednesday. Same workout, basically, but actually I had to put forth more ‘effort’ on Wednesday. Swami would say that’s natural to have ebbs and flows. And he is right, I know that. And the reasons for that are several: adequacy of rest, fitness level, mental focus, hydration level, did you have a candy bar beforehand, is the moon full, and for some….what time of the month is it. Some of these variables can be controlled or mitigated and some cannot.
The second reason was a ‘disagreement’ on the Dragon Door forum about whether there is a fat burning ‘zone.’ One camp maintains that there is a fat burn zone and that lengthy aerobic work does indeed burn fat. The other camp’s point is that even anaerobic work burns fat long term, and points to studies that support that anaerobic exercise when compared to aerobic exercise actually burns more fat long term. After all sprinters are just as fit as marathon runners are.
Since my swings are highly anaerobic and I have lengthy bike rides for endurance and fat burning, I wanted to get to the bottom of the argument.
FAT BURN
The first article I read was by the incredible Clarence Bass: http://cbass.com/FATBURN.HTM
Here’s a couple of excerpts:
In the moderate-intensity group, seven active young male physical education majors exercised on stationary bicycles 5 days per week for 6 weeks at 70% of V02max, 60 minutes each session. V02max was measured before and after the training and every week during the 6 week period. As each subject's V02max improved, exercise intensity was increased to keep them pedaling at 70% of their actual V02max. Maximal accumulated oxygen deficit was also measured, before, at 4 weeks and after the training.
(It should be noted that 70% is the bottom of the ‘Aerobic Zone.’ and is actually a very slow pace. – Scoundrel)
A second group followed a high-intensity interval program. Seven students, also young and physically active, exercised five days per week using a training program similar to Japanese speed skaters. After a 10-minute warm-up, the subjects did seven to eight sets of 20 seconds at 170% of V02max, with a 10 second rest between each bout. Pedaling speed was 90-rpm and sets were terminated when rpms dropped below 85. When subjects could complete more than 9 sets, exercise intensity was increased by 11 watts. The training protocol was altered one day per week. On that day, the students exercised for 30 minutes at 70% of V02max before doing 4 sets of 20 second intervals at 170% of V02max. This latter session was not continued to exhaustion. Again, V02max and anaerobic capacity was determined before, during and after the training.
Findings: The moderate-intensity endurance training program produced a significant increase in V02max (about 10%), but had no effect on anaerobic capacity. The high-intensity intermittent protocol improved V02max by about 14%; anaerobic capacity increased by a whopping 28%.
But what about the fat burn?
Angelo Tremblay, Ph.D., and his colleagues at the Physical Activities Sciences Laboratory, Laval University, Quebec, Canada, challenged the common belief among health professionals that low-intensity, long-duration exercise is the best program for fat loss. They compared the impact of moderate-intensity aerobic exercise and high-intensity aerobics on fat loss. (Metabolism (1994) Volume 43, pp.814-818)
The Canadian scientists divided 27 inactive, healthy, non-obese adults (13 men, 14 women, 18 to 32 years old) into two groups. They subjected one group to a 20-week endurance training (ET) program of uninterrupted cycling 4 or 5 times a week for 30 to 45 minutes; the intensity level began at 60% of heart rate reserve and progressed to 85%. (For a 30-year-old, this would mean starting at a heart rate of about 136 and progressing to roughly 170 bpm, which is more intense than usually prescribed for weight or fat loss.)
The other group did a 15-week program including mainly high-intensity-interval training (HIIT). Much like the ET group, they began with 30-minute sessions of continuous exercise at 70% of maximum heart rate reserve (remember, they were not accustomed to exercise), but soon progressed to 10 to 15 bouts of short (15 seconds progressing to 30 seconds) or 4 to 5 long (60 seconds progressing to 90 seconds) intervals separated by recovery periods allowing heart rate to return to 120-130 beats per minute. The intensity of the short intervals was initially fixed at 60% of the maximal work output in 10 seconds, and that of the long bouts corresponded to 70% of the individual maximum work output in 90 seconds. Intensity on both was increased 5% every three weeks.
As you might expect, the total energy cost of the ET program was substantially greater than the HIIT program. The researchers calculated that the ET group burned more than twice as many calories while exercising than the HIIT program. But (surprise, surprise) skinfold measurements showed that the HIIT group lost more subcutaneous fat. "Moreover," reported the researchers, "when the difference in the total energy cost of the program was taken into account..., the subcutaneous fat loss was ninefold greater in the HIIT program than in the ET program." In short, the HIIT group got 9 times more fat-loss benefit for every calorie burned exercising.
So…why is that? The bottom line is that compared to moderate-intensity endurance exercise, high- intensity interval exercise causes more calories and fat to be burned subsequent to the workout
OK – takeaway is: high intensity workouts are good. Benefits include increase VO2max and anaerobic capacity as well as long term fat loss. But, I didn’t really get an answer to my question – Is there a fat burn zone? More to come…
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