“For a long time it had seemed to be that life was about to begin… real life. But there was always some obstacle in the way, something to be got through first, some unfinished business, time still to be served, a debt to be paid. Then life would begin. At last it dawned on me that these obstacles were my life.”

                                                       -Fr. Alfred D’Souza

How Long? How Often?

Research on exercise options for busy people shows that much can be accomplished in 2 days vs. 3 days, and 20 minutes vs. 60 minutes

By Wayne L. Westcott, Ph.D

Research indicates that about 75 percent of American adults do not exercise and are overweight.  While most people understand that lack of exercise can lead to fat accumulation, they typically are unaware of the physiological relationships that link inactivity and weight gain.

In addition to using fewer calories, inactive adults lose between one-half and one pound of muscle per year.  This results in a lower resting metabolism that further reduces the calories utilized on a daily basis.  Due to few calories being expended, even eating the same quantity of food causes weight gain.  Dieting is largely unsuccessful because it generally results in more muscle loss and an even lower metabolic rate.

People need to understand that, for the most part, the problem of too much weight is really a problem of too little exercise.  More than that, however, an exercise program must include strength training to replace muscle and restore resting metabolic rate.

The importance of strength training is illustrated in a study at Tufts University.  After three months of basic strength exercise, the senior subjects added 3 pounds of lean (muscle) weight, lost 4 pounds of fat weight, raised their resting metabolism by 7 percent and increased their daily calorie intake by 15 percent.

But how much strength training is necessary, and how much time must be allotted for the overall exercise cite lack of time as their main reason for remaining inactive, a time-efficient training program would appear to be advantageous.

Most people in the fitness field consider a three-day-per-week, one –hour-per-session exercise program standard for making significant improvements in body composition.  The hour training session is typically divided into about 25 minutes of endurance exercise, 25 minutes of strength exercise and five minutes each of warm-up and cool-down activities. But studies show that a program consisting of less time can be almost as beneficial.

Two vs. three days per week

In a large research study, 716 previously inactive adults who performed 25 minutes of endurance exercise, 25 minutes of strength exercise and five minutes each of warm-up and cool-down activities three days a week for eight weeks experienced a 2.2 percent improvement in body composition.  As shown in Table 1, they lost 4.6 pounds of fat weight and gained 2.5 pounds of lean (muscle) weight.

Table 1:

2 Vs. 3 Days

In the same study, 416 previously sedentary men and women performed the identical exercise protocol, but trained only two days a week.  After eight weeks, they experienced a 2.0 percent improvement in body composition.  As presented in Table 1, these participants lost 4.0 pounds of fat weight and added 2.2 pounds of lean (muscle) weight.

On average, the subjects who trained two days per week made 88 percent as much improvement in their body composition parameters as those who exercised three days per week.  It would therefore appear that training only twice a week is effective for making significant changes in fat weight and lean weight in previously inactive adults.

From a practical perspective, it is noteworthy that the two training days in this study were Tuesdays and Thursdays.  In most fitness facilities, Tuesday and Thursdays are less crowded than Mondays, Wednesdays, and Fridays, which is advantageous for attending to beginning participants.

20 minutes vs. 60 minutes

A study of 59 previously sedentary participants was conducted to determine whether 20-minute exercise periods were sufficient for improving body composition and physical fitness.  Each session included 15 minutes of endurance exercise and five minutes of strength training.  The aerobic activity was either stationary cycling or stepping, and a typical strength workout was set of leg presses (quadriceps, hamstrings, gluteals), one set of bench presses (pectoralis major, deltoids, triceps) and one set of seated rows (latissimus dorsi, biceps).

After eight weeks of training, the previously inactive men and women improved their body composition by 2 percent, losing 4 pounds of fat weight and adding 2 pounds of lean (muscle) weight.  They also increased their muscle strength by 23 percent and improved their cardiovascular endurance by 12 percent.  These finding indicate that relatively brief exercise sessions can be effective for improving both body composition and physical fitness in formerly sedentary adults.  In fact, the changes in fat weight and lean weight for the 20-minute-per-session exercisers in this study and the 60-minute-per-session exercisers in the previously presented study were quite similar.

Table 2:

20-min. Sessions

Understanding study results

Do these results imply that training periods longer than 20 minutes are unnecessary?  Not at all.  However, they do suggest that unfit individuals may need less exercise than they think to stimulate desirable physical adaptations.  While well-conditioned participants may benefit from longer training sessions, those with low fitness levels may have difficulty maintaining productive levels of exercise intensity for extended periods.  Therefore, 20-minute workouts may be worth trying with people who are unaccustomed to physical activity.

Because lack of time is the most frequently stated reason for not exercising, the results of these studies are good news for time-pressured men and women.  For those who don’t like to exercise but understand the need to do so, the 20-minute training session should enhance their workout compliance.

The Surgeon General’s recommendation for 30 minutes of physical activity most days of the week is certainly a step in the right direction.  However, adding some strength training should be beneficial for replacing muscle and increasing metabolic rate, which appear to be key factors in attaining and maintaining desirable body composition.  Because a few multiple-muscle strength exercises seem to be sufficient, a three-to –five-station strength circuit may be an attractive facility feature for time-pressured individuals.  Table 3 presents a sample five-station strength training circuit that should take no more than 10 minutes for completion.