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Research Bites

Bracko, Michael R. Ed.D., FACSM

doi: 10.1249/FIT.0b013e3181c65583

Chocolate Milk - the Drink of Champions; Twenty-Meter Shuttle Run - Maximum Effort in Kids; Yoga as a Treatment for Rheumatoid Arthritis; Good News About Video Game Cycling.

Michael R. Bracko, Ed.D., FACSM, is an exercise physiologist and director of the Institute for Hockey Research and the Occupational Performance Institutein 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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In this study, the researchers investigated the effect of chocolate milk (Mars Refuel chocolate milk), a fluid replacement drink (Gatorade, flavor unknown), and a carbohydrate replacement drink (Endurox R4) on endurance performance after a glycogen-depleting cycling trial.

Nine male trained cyclists with a mean age of 25.4 years were the subjects in this study. The subjects performed three experimental trials, in a randomized counterbalanced order, consisting of a glycogen-depleting ride, a 4-hour recovery period, followed by a ride to exhaustion at 70% power at maximal oxygen uptake. Within 60 seconds of the start of the recovery period and 2 hours into the recovery period, the subjects drank Mars Refuel chocolate milk, Gatorade, or Endurox R4. Each trial was separated by 1 week.

The results indicate that the subjects cycled 51% and 43% longer after drinking Mars Refuel chocolate milk (32 ± 11 minutes) compared with the Endurox R4 carbohydrate replacement drink (21 ± 8 minutes) and the Gatorade fluid replacement (23 ± 8 minutes). The researchers indicate that the carbohydrates in chocolate milk (glucose, fructose, sucrose, and lactose) and the carbohydrate replacement drink (glucose, fructose, and maltodextrin) have high solution osmolarity and similar peak oxidation rates during exercise, but the lack of sucrose in the carbohydrate replacement drink may have affected liver glycogen repletion, therefore, adversely affecting the availability of blood glucose and endurance time. Similarly, the higher fat content of chocolate milk compared with the carbohydrate replacement drink could have resulted in higher free fatty acid concentrations during cycle time to exhaustion (2).

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The 20-meter shuttle run is a commonly used and easy to administer test to measure predicted maximum oxygen uptake. In this study from the University of Essex, United Kingdom, the authors investigated if maximum effort, as evidenced by peak heart rate, was attained during the 20-meter shuttle run. The subjects in the study were 208 11- to 16-year-old boys and girls (104 boys and 104 girls).

The test protocol was the FITNESSGRAM PACER, which is a modified version of the original multistage 20-meter shuttle run test. Testing was done in groups of 30, and the subjects had not practiced the test before evaluation but had done it before in physical education class.

Peak heart rate was recorded (with heart rate monitors) as the highest heart rate achieved within 5 seconds of the end of the test (inability to maintain pace or volitional end of the test). The average peak heart rate achieved in the study was 196 beats per minute. This study used a non-age-related criterion heart rate of 185 taken from a previous research. There was a statistically positive relationship between peak heart rate and 20-meter shuttle run performance. Therefore, the investigators suggest that the 20-meter shuttle run elicits a maximal effort in 11- to 16-year-old boys and girls. The authors further suggest that the findings of the study are consistent for children who were normal weight, underweight, overweight, and obese (3).

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In this timely study, the researchers investigated the effects of Hatha Yoga on activities of daily living (Health Assessment Questionnaire Disability Index), perception of pain (visual analog scale for pain), depression (Beck Depression Inventory), balance (Berg Balance Test), diurnal and awakening cortisol levels, and resting heart rate on women diagnosed with rheumatoid arthritis. Sixteen postmenopausal women aged 45 to 75 years who had rheumatoid arthritis for 17.3 to 19.3 years were subjects in the study.

There was a yoga group (n = 9) who participated in Hatha Yoga three times per week, 75 minutes per session, for 10 weeks. There also was a control group (n = 7) who did not participate in yoga.

The results indicate that there were no differences between groups at baseline testing. The authors indicate that considering the typical progression of rheumatoid arthritis, the most noteworthy result in physical function was the improvement in the Health Assessment Questionnaire Disability Index. The yoga group had a 35% decrease in disability rating, whereas the control group had a 22% increase in disability rating. The yoga group also had a significant decrease in their perception of pain. The control group had no change in perception of pain. Yoga participants reported fewer symptoms of depression after yoga. There were consistent improvements in the balance scores on the Berg Balance Test in the yoga group, whereas the control group did not show improvements. There were no differences between groups in diurnal and awakening cortisol levels or resting heart rates. The authors conclude that the positive outcomes of this study offer support for the use of Hatha Yoga for women with rheumatoid arthritis and that yoga can be considered a treatment option (1).

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The purpose of this study from Canada was to investigate the metabolic requirements of interactive video stationary cycling compared with traditional stationary cycling. Seven males (mean age, 25.9 years) and seven females (mean age, 23.4 years) participated in the study. The subjects were tested three times: 1. incremental cycling for the measurement of maximal aerobic power and peak workload; 2. traditional cycling using 5-minute constant workloads of 25%, 50%, and 75% of maximal power output; and 3. the identical cycling protocol while playing interactive video games. The subjects were measured for oxygen consumption, energy expenditure, heart rate, and rating of perceived exertion.

The investigators indicate that the results are unique because this is the first study to show that interactive video game cycling had higher metabolic requirements than stationary cycling. During video game cycling, steady-state heart rate (26% ± 18% and 14% ± 13%), energy expenditure (61% ± 41% and 25% ± 21%), and oxygen consumption (34% ± 17% and 18% ± 12%) were significantly higher at 25% and 50% workloads than traditional cycling. There were no significant differences in the rating of perceived exertion between conditions at any workload. The authors conclude that video cycling may be a novel and attractive way to exercise for people who are struggling to become more physically active (4).

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1. Bosch PR, Traustadóttir T, Howard P, Matt KS. Functional and physiological effects of yoga on women with rheumatoid arthritis. Altern Ther Health Med. 2009;15(4):24-31.
2. Thomas K, Morris P, Stevenson E. Improved endurance capacity following chocolate milk consumption compared with 2 commercially available sports drinks. Appl Physiol Nutr Metab. 2009;34(1):78-82.
3. Voss C, Sandercock G. Does the twenty meter shuttle-run test elicit maximal effort in 11- to 16-year olds? Pediatr Exerc Sci. 2009;21(1):55-62.
4. Warburton DER, Sarkany D, Johnson M, et al. Metabolic requirements of interactive video game cycling. Med Sci Sports Exerc. 2009;41(4):920-6.
© 2010 American College of Sports Medicine.