ACSM'S Health & Fitness Journal:
doi: 10.1249/FIT.0b013e31828cb4f2
COLUMNS: Research Bites

Research Bites

Bracko, Michael R. Ed.D., FACSM

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Michael R. Bracko, Ed.D., FACSM, is an exercise physiologist and director of Dr. Bracko’s Fitness in Calgary, Canada. He is a fitness educator, presenter, media consultant, and writer. He works in sports physiology for performance enhancement for hockey players. He is the strengh and conditioning coach for the U.S.A. Men’s Deaflympic Hockey Team. He also works in occupational physiology in the areas of back injury prevention, ergonomics, work-station stretching, and pre-work warm-up.

Disclosure: The author declares no conflict of interest and does not have any financial disclosures.

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COMPRESSION GARMENTS — TO IONIZE OR NOT

In this study, which gives more information about the ongoing interest in compression garments and exercise performance, the investigators used 10 highly trained triathletes and cyclists and compared nonionized, ionized, and standard running tights while performing three cycling sprint trails and three endurance cycling trials. The cycling trials consisted of the following: 1) Sprint — 30-second cycle test at 150% of the power output to elicit V˙O2max followed by a 3-minute recovery period, followed by a 30-second Wingate test with resistance set at 0.075 × body mass, 2) Endurance — 30 minutes of constant-intensity cycling at 60% of V˙O2max followed by a 5-minute passive recovery period and concluded with a 10-km time trail on cycle trainer. In each trial, the subjects wore a different compression garment. The premise of the research is that recent developments in compression garment design have seen negatively charged ions incorporated into the fabric — in an attempt to improve performance.

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The results indicate that there was no significant effect of garment type on Wingate measures, such as peak power, mean power, or fatigue. There was an effect of garment type on blood lactate in the sprint and endurance, but post hoc tests only detected a significant difference between the standard control and the nonionized garments in the endurance trial. Moreover, oxygen uptake, heart rate, and time trail performance were unaffected by either type of garment.

The authors conclude that although ionized and nonionized compression garments are widely used in sports, in their study, there was no advantage in exercise performance when wearing either garment (1).

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VIBRATION TRAINING FOR STRENGTH DEVELOPMENT

The purpose of this study was to compare strength and power development when using a total-body vibrating platform alone compared with a combination of vibration and conventional strength training. Eighteen national-level female athletes (soccer and softball) (mean age, 23.8 years) trained in one of three groups: 1) whole-body vibration, 2) conventional strength training, or 3) combination of vibration and conventional for 8 weeks.

Each subject completed 6 sets of 6 reps of a 90-degree squat with 3 minutes of rest between each set. The weight lifted was set at 60% and 30% of each subject’s body mass for conventional strength training and the combination group, respectively. The weight was increased by about 6% for conventional training and 3% for combination group, respectively.

Subjects were tested on the following variables: maximum voluntary isometric contraction, rapid leg extensions, 3 maximal counter movement vertical jump, and continuous counter movement jumps for 15 seconds.

The results indicate that whole-body vibration training alone or in combination with strength training did not significantly improve force and power compared with strength training. Therefore, the authors conclude that, in their study with female athletes, vibration training cannot substitute for strength training. They concede, however, that the effects of vibration training may be limited by the behavior of the commercial platforms used for training (3).

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YOGA IS GOOD FOR LOW-BACK PAIN

The purpose of this study was to evaluate the effect of yoga on 53 male and female military veterans with chronic low-back pain. The subjects completed a battery of questionnaires before their first yoga class and again 10 weeks later. The questionnaires included measures of pain (Pain Severity Scale), depression, energy/fatigue, and health-related quality of life. Yoga attendance and home practice of yoga also were measured. Subjects who completed both assessments had a mean age of 53 years, were well educated, 41% nonwhite, 49% married, and had varying employment statuses.

The results indicate that female subjects had significantly larger decreases in depression and pain and had higher increases in energy and mental health than the men who participated. The groups did not differ in yoga attendance or home practice of yoga.

The authors conclude that yoga may have better results in decreasing symptoms of low-back pain in female military veterans than male veterans but do not suggest why. The authors also indicate that the results of their study could be tentative because of the small sample size and quasi-experimental study design. The good news is that they are undertaking a larger study to better answer the question (2).

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MORE SLEEP — MORE PHYSICAL ACTIVITY IN KIDS

In this study, the researchers investigated how number of hours of sleep during the week and on weekends affected physical activity in 856 children (11.1 years, 389 boys,). Physical activity was measured using accelerometry, and data were collected for 7 days. Subjects had to wear the accelerometer a minimum of 10 hours for at least 3 weekdays and 1 weekend day. Physical activity variables included total physical activity (counts per day), mean counts (counts per minute), and time spent in various levels of movement intensity.

Sleep was measured by parent reporting and put into 3 categories: less than 9 hours, 9 to 10 hours, and more than 10 hours. The number of hours of sleep and physical activity were compared to determine whether sleep increased, decreased, or was maintained across the week, and relationships with activity and overweight/obesity were examined. Subjects who slept 9 to 10 hours were not different from other sleep categories.

The results indicate that children who slept the least amount (<9 hours) on weekdays were significantly heavier, had a greater body mass index, and were more likely classified as overweight/obese compared with children who slept more than 10 hours per night. On the weekends, short-duration sleepers (<9 hours) were heavier and were more often classified as overweight/obese compared with those sleeping 9 hours or more per night, yet differences in activity were more pronounced between short and intermediate sleep groups.

Weekday-weekend sleep regularity was important because the overall physical activity intensity was higher among children who maintained 9 hours or more of sleep compared with those engaging in weekend catch-up sleep.

The authors conclude by suggesting that there is a link between sleep duration and physical activity in children, specifically, the overall intensity of activity and the accumulation of light physical activity over the weekend. In addition, children who maintain recommended levels of sleep across the week have the most healthy and consistent levels of physical activity. Getting enough sleep for children can be promoted as a good health strategy (4).

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References

1. Burden RJ, Glaister M. The effects of ionized and nonionized compression garments on sprint and endurance cycling. J Strength Cond Res. 2012; 26 (10): 2837–43.

2. Groess EJ, Weingart KR, Johnson N, Baxi S. The benefits of yoga for women veterans with chronic low back pain. J Altern Complement Med. 2012; 18 (9): 832–8.

3. Preatoni E, Colombo A, Verga M, et al. The effects of whole-body vibration in isolation of combined with strength training in female athletes. J Strength Cond Res. 2012; 26 (9): 2495–506.

4. Stone MR, Stevens D, Faulkner GE. Maintaining recommended sleep throughout the week is associated with increased physical activity in children. 2012 Nov 29. doi:pii: S0091-7435(12)00592-0. 10.1016/j.ypmed.2012.11.015. [Epub ahead of print].

© 2013 American College of Sports Medicine

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