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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 Occcupational 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. Deaf Olympic Men's Ice Hockey Team; 2) the health and fitness industry, by contributing to SELF Magazine's online Forum and by presenting at health and fitness meetings such as the ACSM's Health & Fitness Summit & Exhibition; and 3) as an occupational physiologist, in the areas of injury prevention, ergonomics, workstation stretching, and prework warm-up.

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Dose-Response for Strength Development

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In this published symposium, the authors reviewed recent meta-analyses on the validity of single or multiple sets of weight training for maximum strength development. The research indicates that there are distinct muscle adaptations and dose-response relationships that correspond to different populations and training status.

The analysis investigated the dose-response relationships of (1) untrained individuals, (2) recreational weight lifters, and (3) athletes. The meta-analysis used 177 studies to investigate intensity, frequency, volume of training, and results of the training.

For untrained individuals, maximum strength gains are elicited at a mean intensity of 60% of one repetition maximum (1 RM), a mean frequency of 3 days/week, and a mean volume of 4 sets/muscle group. In the recreational weight lifters, maximum strength gains are found with a mean intensity of 80% of 1 RM, a mean frequency of 2 days/week, and a mean training volume of 4 sets/muscle group. For the athletic population, maximum strength gains are realized with a mean intensity of 85% of 1 RM, a mean frequency of 2 days/week, and a mean volume of 8 sets/muscle group.

The researchers also meta-analyzed 75 studies to determine if weight training to failure was necessary for maximum benefit. They found that performing repetitions to failure does not provide greater strength gains than not training to failure (1).

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Watching TV to Get Active

In this study, the researchers investigated the effect of the daily television show, "The Netherlands on the Move," on promoting physical activity in people over 55 years. "The Netherlands on the Move" show was part of a national program for promoting activity to the 4 million people older than 55 years.

There was a baseline test and follow-up after 7 months (n = 362). The main outcome measures were intent to exercise and actual participation in exercise. The determinants included attitude, social influences, self-efficacy, age, sex, education, knowledge about the health benefits of exercise, lifestyle habits, stage of change in exercising, and perceived barriers.

The results show that watching the TV program attracted 21% of the inactive people at baseline and increased knowledge of exercise and benefits of exercise. The best predictors of intent to participate in exercise were attitude, social influences, self-efficacy, age, and sex. Actual participation in exercise was best predicted by older age, sex (females), knowledge of exercise and health benefits, and a lower number of perceived barriers. The researchers conclude that "The Netherlands on the Move" was a successful and inexpensive method of getting previously inactive older people to exercise (2).

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Effect of Cold on Shock Absorption of Running Shoes

In this study from the Mayo Clinic, the researchers investigated the effect of temperature on the shock absorption of the soles of four different running shoes (Adidas a3, Adidas Supernova, Asics Gel Nimbus IV, and Nike Air Triax). The shoes were measured for absorption at temperatures of −20, −10, 0, 10, 20, 30, 40, and 50 °C. Shock absorption was evaluated by the deceleration of the shoe as measured with a mechanical impactor. The results show that shock absorption decreased significantly with cold temperature for each shoe. The Adidas a3 exhibited significantly lower shock absorption at cold temperatures compared with the other shoes.

The authors conclude that cold temperatures significantly reduce the shock absorption of commonly used running shoes, especially the Adidas a3. These findings can have important applications for runners who have a history of leg and hip injuries (3).

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Getting People to Use the Stairs

In this study, the researchers investigated the effect of two interventions to promote using the stairs among female employees in a five-floor office. The first intervention was a sign indicating a relationship between using the stairs and improved health/fitness. The sign was put on the wall between the staircase and the elevator. The second intervention was an e-mail from the worksite doctor sent a week after the sign was put up. The e-mail had information about the health benefits of regularly using the stairs.

The results show that stair use increased significantly from 69% at baseline to 77% in the week after the first intervention. Compared with the first intervention, stair use increased significantly to 85% in the week after the second intervention. However, stair use decreased to 67% in a follow-up 1 month after the sign was removed, and was not significantly different from baseline.

The authors conclude that simple and inexpensive interventions such as a "health sign" and an e-mail from a worksite doctor can encourage female employees to use the stairs. They also suggest that a continued effort to keep people active is important (4).

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"Self-Talk" and Regular Exercise

The authors of this study investigated the physical activity levels of middle-aged (40-55 years) and older men and women (>56 years) as well as their intentions for future activity. Random telephone surveys stratified for age, sex, and geographic location assessed the weekly physical activity and the plans for exercise among 40 adults.

The results show that adults aged 40-55 years expended more energy both at work and leisure time than adults aged 56 years or older. The results regarding "self-talk" indicated that "self-talk" strategies occurred among 88% of the respondents. An important strategy used by the physically active people was to ignore negative "self-talk" and just start exercising before they talked themselves out of their workout.

The authors conclude that the group to target with positive triggering messages and reminders are those who want to exercise but are not regular with exercise. Messages to nonexercisers such as "Just Do It" may be important to help adults who are trying to increase their physical activity (5).

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References

1. Peterson, M.D., R.R. Matthew, B.A. Alvar. Applications of the dose response for muscular strength development: A review of meta-analytic efficacy and reliability for designing training prescription. Journal of Strength and Conditioning Research 19(4):950-958, 2005.

2. Hopman-Rock, M., J.A. Borghout, M.T. Leurs. Determinants of participation in a health education and exercise program on television. Preventive Medicine 41(1):232-239, 2005.

3. Dib, M.Y., J. Smith, K.A. Bernhardt, et al. Effect of environmental temperature on shock absorption properties of running shoes. Clinical Journal of Sports Medicine 15(3):172-176, 2005.

4. Auweele, Y.V., F. Boen, W. Schapendonk, et al. Promoting stair use among female employees: the effects of a health sign followed by an e-mail. Journal of Sports and Exercise Psychology 27(2):143-147, 2005

5. Cousins, S.O., M.M. Gillis. Just do it…before you talk yourself out of it: the self-talk of adults thinking about physical activity. Psychology of Sport and Exercise 6(3):313-334, 2005.

© 2006 American College of Sports Medicine

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