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Research Bites

Bracko, Michael R. Ed.D., FACSM

doi: 10.1249/FIT.0b013e318229cc00

Interval Training for Heart Disease Patients; Core Training and Throwing Velocity; Barefoot Running; Exercising Before Breakfast.

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

Disclosure: Author declares no conflicts of interest.

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With the popularity of high-intensity interval training (HIIT), this timely study investigated the effect of HIIT and strength training (horizontal leg press) on coronary artery disease (CAD) patients. The researchers studied the effect of the training protocols on peak stroke volume, peak oxygen uptake, and submaximal walking performance.

Eight CAD patients (61.4 years) performed 30 interval training sessions using 4 × 4–minute intervals at 85% to 95% of peak heart rate. Ten CAD patients (66.5 years) performed 24 sessions of maximal horizontal leg press.

The authors found that the interval training group significantly increased their peak stroke volume by 23%. In addition, the interval training group significantly increased their peak oxygen uptake by 17%. The horizontal leg press group had no change in peak stroke volume or peak oxygen uptake. However, they did improve their submaximal walking performance by 35%.

The results of this study help decrease any fear that may exist that CAD patients cannot successfully engage in HIIT. As such, HIIT is not only for healthy, motivated people (2).

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This study from Norway and Portugal investigated the effect of core stability training on maximal throwing velocity of female handball players. Handball is a team sport in which two teams of seven players each pass a ball to throw it into the goal of the other team.



Twenty-four female high school handball players were divided into a core training group or a control group. The core training group performed their exercises twice per week for 6 weeks. The control group continued their regular handball training. The core training group performed 13 exercises all designed to engage the core stabilizing muscles. To the best of the author’s understanding, the exercises incorporated prone, side-lying, crunches with the one or both feet in a hanging sling, “Superman” exercise while holding onto the sling at chin level and balancing on their knees and toes, one-leg squat on stable and unstable surfaces, and sling push-ups.

The results indicate that there were no differences in throwing velocity between the training and control groups in the pretest. However, in the posttest, the core training group significantly increased their throwing velocity by 4.9% (17.9 to 18.8 m per second) but was unchanged in the control group. The authors suggest that core stability training using unstable, closed kinetic chain movements can enhance throwing velocity. They suggest that a stronger and more stable lumbopelvic-hip complex may contribute to higher rotational velocity in multi-segmental movements (3).

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This study investigated the oxygen cost of running barefoot versus running shod (wearing modern running shoes) on the treadmill and on a running track. Ten recreational runners, five male and five female subjects (23.8 years) participated in four running conditions: barefoot on treadmill, shod on treadmill, barefoot on ground, and shod on ground. For each running condition, subjects ran for 6 minutes at 70% of V˙Omax pace while V˙O2, heart rate, and rating of perceived exertion were measured.

The results indicate that running with shoes showed significantly higher V˙O2 values on the treadmill and while running on the track. Heart rate and rating of perceived exertion also were significantly higher when running with shoes. For the ground running and treadmill running conditions, V˙O2 while running shod was 5.7% and 2.0% higher than running barefoot, respectively. The authors concluded that when running at 70% V˙O2max pace, barefoot running is more economical in terms of V˙O2, heart rate, and rating of perceived exertion than running shod, both on ground and on a treadmill (1).

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The purpose of this study was to compare differences in fat metabolism during and after exercising in a fasted state or after eating a small breakfast. The investigators compared the effect of eating or not eating on oxygen consumption (V˙O2) and substrate utilization (estimated by the respiratory-exchange ratio) on eight healthy young men.



The subjects performed the same training session (36 minutes of running on treadmill at 65% maximum heart rate) in the morning in two tests: fasting condition without food intake and feeding condition after breakfast.

The feeding condition after breakfast increased both V˙O2 and respiratory-exchange ratio significantly compared with the fasting condition. Twelve hours after the training session, V˙O2 was still higher in the feeding group, but respiratory-exchange ratio was significantly lower in the feeding group test, indicating greater lipid (fat) utilization. The difference was still significant 24 hours after exercise.

The authors conclude that when moderate endurance exercise is done to lose body fat, fasting before exercise does not enhance fat utilization after exercise. Moreover, it is advisable to eat a small meal before exercise (4).

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1. Hanson NJ, Berg K, Deka P, Meendering JR, Ryan C. Oxygen cost of running barefoot vs running shod. Int J Sports Med. 2011;32:401–6.
2. Helgerud J, Karlsen T, Kim WY, et al. Interval and strength training in CAD patients. Int J Sports Med. 2011;32(1):54–9.
3. Saeterbakken AH, Van Den Tillaar R, Seiler S. Effect of core stability training on throwing velocity in female handball players. J Strength Cond Res. 2011;25(3):712–8.
4. Paoli A, Marcolin G, Zonin F, Neri M, Sivieri A, Pacelli QF. Exercising fasting or fed to enhance fat loss? Influence of food intake on respiratory ratio and excess postexercise oxygen consumption after a bout of endurance training. Int J Sport Nutr Exerc Metab. 2011;21(1):48–54.
© 2011 American College of Sports Medicine.