From The Desk Of Clarence Bass
Training Frequency: Twice a Week, Four, Six?
A new study from researchers at the University of Alabama at Birmingham, reported online January 30, 2013, in Medicine & Science in Sports & Exercise, found that training 2 times, 4 times, or 6 times a week all build the same level of fitness. Training four times, however, burned more total calories than two or six times. Six-times-a-week training actually reduced daily energy expenditure!
Gretchen Reynolds reported the study in the New York Times (February 13, 2013), calling it “commendable.” Alex Hutchinson, writing on Runnersworld.com a few days later, raised questions. We’ll discuss them at the end of this piece.
I’ve been saying for a very long time that less training often produces better results. In Lean For Life, I recommended 2 weight workouts and 2 aerobic workouts. In Challenge Yourself, I reported excellent results from one high-intensity weight session and one high-intensity aerobic session. In Great Expectations, I suggested training three times a week: one weights, one aerobics, and a combination of weights and aerobics. In my experience, all three frequencies work well—depending on the circumstances of the individual—but more is likely to be too much of a good thing.
In my first book, Ripped, I told how I sacrificed muscle lifting six days and riding my bike on the seventh day. The next year, 1978, I dropped back to four times a week and won my class in the Past 40 Mr. America.
The new study mirrors my experience over many years.
While the study has limitations, it makes some very telling points.
Dr. Gary R. Hunter and colleagues randomly assigned 72 women, 60-74 years old, to one of three training groups: 1 day of aerobic and 1 day of resistance (1+1); 2 aerobic and 2 resistance (2+2); or 3 aerobic and 3 resistance (3+3). The women gradually progressed to 40 minute workouts: aerobic exercise (jogging, biking, etc) at 80% of maximum heart rate or two sets of 10 reps on 10 resistance exercises at 80% of one-rep max. Measurements were taken before and after 16 weeks of training. (I’ll explain below why older women were chosen.)
As Gretchen Reynolds aptly put it, the researchers were looking for a “Goldilocks-like” frequency, just right for building fitness and burning calories, not too much and not too little. They reasoned that infrequent training was likely to short change results, while too much would produce fatigue and curtail overall results. They hoped to find an optimal middle ground.
The workouts were designed to build both muscle and endurance—and they did. All three groups increased fat free mass, strength and aerobic fitness, and lost fat mass. As noted above, the fitness gains were essentially the same for all three training frequencies.
That was a surprise. They expected that 2+2 would produce better fitness results than either 1+1 or 3+3. It didn’t come out that way. Another result, however, came out as expected. Hunter and his colleagues predicted that 2+2 would expend more total energy (TEE) than the other two frequencies—and it did.
Hunter et al were especially interested in physical activity other than formal exercise. Total energy expenditure (TEE) is an important contributor to metabolic health, while non-exercise (free living) energy expenditure (AEE) is a key factor in weight control.
TEE and AEE become more important with age. That’s why older women were chosen for the study. Young people are generally more active. Ability to perform daily tasks reaches a peak at 30 and declines thereafter. The decline seems to result mainly from of declining physical activity. The effect of training frequency on overall activity would be especially important for older women.
Let’s dig down into what the researchers found.
We’ve already said that 2, 4, and 6 weekly training sessions produced essentially the same gains in muscle, strength, and aerobic fitness. The women who trained twice a week gained just as much muscle and fitness as those who worked out four or six times a week. The main difference was in energy expenditure.
Two aerobic and two resistance sessions burned substantially more total calories than the other two groups. The 1+1 group also expended more total energy at the end of the training period, but total energy expenditure increased considerably more in the 2+2 group. Again, 3+3 produced an actual reduction in total energy expenditure.
The largest and most noticeable difference between the three groups was in non-exercise energy expenditure, which increased significantly in the 2+2 training group (+200 daily calories), while 1+1 showed a trend toward increase (+68 calories a day). The 3+3 group, however, saw a significant reduction in non-exercise energy expenditure (-150 calories per day, -192/day during the last weeks of exercise).
What happened? How could the women train six days a week for 16 weeks and end up burning fewer calories?
The researchers expected to find an increase in cytokines in the blood of the 3+3 group. Cytokines are a pro-inflammatory substance linked to stress and overdoing physically. But there was no change in cytokines or other signs of stress or perceptions of fatigue or depression.
“It is unlikely that the 3+3 day/week training overstressed these older women,” Hunter et al wrote in discussing their results. “The most consistent complaint for the 3+3 group was the very large time commitment needed for 6 exercise training sessions each week,” they continued. “It is possible the 3+3 group reduced [non-exercise activity] during the week because of time restraints rather than fatigue.”
“We think that the women in the twice-a-week and four-times-a-week groups felt more energized and physically capable” after training than before, said lead author Gary Hunter. This apparently caused them to be more active between workouts.
On the other hand, the women who trained six days a week felt pressed for time. Hunter thinks they began making time-saving choices like driving instead of walking and taking elevators rather than stairs. They apparently over-reacted and ended up expending less total energy than before they began exercising.
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What about the questions raised about the study on Runnersworld.com?
First, Alex Hutchinson wondered whether the findings would be the same for a group of 20-year-old college students. Dr. Hunter and his colleagues acknowledged that their results might be different for men instead of women, and older or younger subjects. Obviously, more research is needed.
Still, the findings make sense. If your training regimen is crowding out other important things in your life or making you uncomfortable, it’s logical to assume that, consciously or unconsciously, you are likely to make adjustments such as driving rather than biking or taking escalators and avoiding stairs. On the other hand, a really committed young person convinced that “more is better” is probably going to make time to work out six times a week, no matter what, while a busy family man with a business to run is more likely to opt for working out 2 or 3 times a week, especially if experience and research suggest that the results may be the same or better.
Mr. Hutchinson agreed that time commitment is important. “To me, a crucial part of a workout plan’s effectiveness is how convenient it is, and how smoothly it fits into your life,” he wrote.
Another question put by Hutchinson is the experience factor. What would happen if the [study] lasted five years, rather than 16 weeks? Would the results be the same? “I suspect not,” he wrote. “It’s more difficult—and may require more workouts—to continue to improve after you’ve taken the low-hanging fruit.”
That’s where we part company. My experience is that long-term progress comes from training harder and less.
The more fundamental finding of this study, Dr. Hunter told Gretchen Reynolds, is that “less may be more.” The women exercising four times a week “had the greatest overall increase in energy expenditure,” he said. But those working out only twice a week “weren’t far behind.”
Yes, as I see it, that is the take away message. Workout at a frequency that suits your energy level and circumstances—and stay active between workouts.
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