ACSM'S Health & Fitness Journal:
doi: 10.1249/FIT.0b013e3181d9f683
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Bracko, Michael R. Ed.D., FACSM

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Michael R. Bracko, Ed.D., FACSM, is an exercise physiologist and director of the Institute for Hockey Research and the Occupational Performance Institute in Calgary, Canada. He is an associate editor for ACSM's Health & Fitness Journal® and works in three areas: 1) sports physiology, where he conducts research on the performance characteristics of female ice hockey players, teaches high performance skating, and serves as physiologist for the University of Alberta Women's Hockey Team and the U.S. Men's Deaf Olympic Ice Hockey Team; 2) the health and fitness industry, by contributing to fitness magazines, consulting, presenting at health and fitness meetings such as the ACSM's Health & Fitness Summit & Exposition; and 3) as an occupational physiologist, in the areas of back injury prevention, ergonomics, workstation stretching, and prework warm-up.

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FREQUENCY OF EXERCISE IS BEST FOR FAT LOSS

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In this study, the investigators looked at changes in body fat mass in sedentary deconditioned subjects who exercised according to the U.S. Surgeon General's recommendation for frequency of exercise (exercise "most days of the week"). A total of 56 females and 24 males participated in the study for 8 weeks. Subjects were prescribed to exercise four times per week at 70% of their maximum heart rate on cardio equipment or on a 10-piece circuit training system. Subjects had their body fat mass measured prestudy and poststudy using a BodPod.

At the end of the study, based on an electronic attendance program, the subjects were categorized into one of four groups based on exercise compliance: 20 subjects who chose not to exercise, 20 subjects who exercised less than two times per week, 20 subjects who exercised two to three times per week, and 20 subjects who exercised four times per week or more.

All groups except the nonexercise group lost body fat mass. But the group who exercised four times per week or more lost significantly more body fat mass than the other groups. The authors indicate that this study was specifically designed to investigate frequency of exercise. Based on the exercise protocol, the authors conclude that the frequency of exercise is more important for body fat mass loss than intensity or duration of exercise (4).

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GET TO THE CORE OF THE MATTER IN RUNNING

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In this study, the investigators looked at the effect of core muscle strengthening on running performance. A total of 28 recreational and competitive runners (10 men, 18 women) participated in the study. The subjects were randomly assigned to a core strengthening group or a control group that did no core strengthening exercises.

The subjects were measured on ground reaction forces with the left foot, lower body functional dynamic stability using the Star Excursion Balance Test, and time to run 5,000 m. The core strengthening group performed five core exercises four times per week for 6 weeks. The exercises included 1) abdominal crunches on a stability ball, 2) back extension on a stability ball, 3) supine opposite one arm/one leg raise to target back/hip extensor muscles, 4) hip raise on a stability ball, and 5) Russian twist on a stability ball.

The results of the study indicate that core strengthening did not have an effect on ground reaction forces with the left foot or lower body functional dynamic stability. However, the core strengthening group participants significantly improved their 5,000-m running time compared with the control group. The authors indicate that the results of this study show that core strengthening may be an effective way to improve running time (3).

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CAN AN ELECTRIC BIKE INCREASE PHYSICAL ACTIVITY?

This study from The Netherlands investigated the potential of an electrically assisted bicycle helping people meet the physical activity guidelines for intensity. On an electrically assisted bicycle, pedaling is supplemented by electric power from a battery. A total of six males and six females, who were regularly active and in good health, were subjects in the study. The subjects were tested three times on the same day by riding an electrically assisted bicycle in three different intensity modes: 1) no support, 2) light support, and 3) high support (from the battery). The subjects cycled on a 4.3-km public track that was almost flat. Subjects were instructed to cycle as if they were commuting to or from work.

The subjects were measured on the following variables: oxygen consumption, heart rate, cycling speed, power output, pedaling rate, comfort sensation, and rating of perceived exertion. The results of the study showed that the average cycling intensity in METs was as follows: 6.1 METs (no support), 5.7 METs (light support), and 5.2 METs (high support). Intensity was significantly lower in the high support group compared with the no support group, and there were no differences between the no support and light support groups. Mean heart rate was significantly higher in the no support group compared with the light support and high support groups. Cycling speed was significantly higher in the light support and high support groups compared with the no support group. Pedal rate was significantly higher in the no support group compared with the light support and high support groups. Power output was significantly different in all three conditions: highest output was in the no support group, and lowest output was in the high support group. Rating of perceived exertion was somewhat hard in the no support group, light in the light support group, and very light in the high support group. The authors conclude that the intensity of cycling on an electrically assisted bicycle in all support modes was sufficient to adhere to the moderate-intensity standard of 3 to 6 METs as stated in the physical activity guidelines for adults (2).

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WEIGHT TRAINING CAN MAKE YOU SMARTER

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The purpose of this study was to investigate the relationship between the intensity of weight training and cognitive performance. A total of 36 males and 32 females were randomly assigned into one of four groups: 1) control, 2) 40% of 10-repetition maximum, 3) 70% of 10-repetition maximum, and 4) 100% of 10-repetition maximum. Subjects performed bench press, right and left rowing, lateral arm raise, and right and left arm curl.

Subjects were tested on day 1 and day 2 on the following variables: heart rate, rating of perceived exertion, and self-reported arousal (Felt Arousal Scale; measures the intensity of arousal). Cognitive performance was assessed on day 1 and before and following treatment on day 2 with the Stoop Test, which evaluates information processing speed, executive abilities, selective attention, and the ability to inhibit habitual responses. On day 1, the subjects were tested for their 10-repetition maximum, and on day 2, they performed one of the four treatment protocols.

The results indicated that peak heart rate, average heart rate, average self-reported arousal (Felt Arousal Scale), and average rating of perceived exertion showed significant differences among the four treatment groups with the greatest values being in the 100% of 10-repetition maximum group, followed by the 70% group, then 40% group, and finally the control group.

Moreover, there was a significant linear effect of exercise intensity on information processing speed and a significant trend for exercise intensity on executive function. The authors conclude that there is a dose-response relationship between the intensity of weight training and cognitive performance such that high-intensity exercise benefits speed of processing but that moderate-intensity exercise is most beneficial for executive function (1).

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References

1. Chang Y, Jennifer L, Etnier JL. Exploring the dose-response relationship between resistance exercise intensity and cognitive function. J Sport Exerc Psychol. 2009;31(5):640-56.

2. Simons M, Van Es E, Hendriksen I. Electically assisted cycling: a new mode for meeting physical activity guidelings? Med Sci Sports Exerc. 2009;41(11):2097-102.

3. Sato K, Mokha M. Does core strength training influence running kinetics, lower-extremity stability, and 5000-m performance in runners? J Strength Cond Res. 2009;23(1):133-40.

4. Willis FB, Smith FM, Willis AP. Frequency of exercise for body fat loss: a controlled, cohort study. J Strength Cond Res. 2009;23(8):2377-80.

© 2010 American College of Sports Medicine

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