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Triathletes, Draft in the Water
A new study suggests that drafting off of an opponent during the swimming leg of a triathlon can improve your cycling leg. Researchers at the National Institute of Sport and Physical Education in France found that swimming directly behind a competitor improves your biomechanical adaptation during the subsequent cycling portion of the race. While drafting during running, biking, and even cross-country skiing has long been common practice—even to the point where it is expected that Olympic competitors will share the lead—the practice is less common among swimmers. A group of male triathletes underwent separate sessions involving a 10-minute bike ride at 75% VO2max, either preceded by a 750-meter swim alone, or a swim in drafting position at the same pace. The decrease in energy expenditure (sometimes referred to as "metabolic load") found during the drafting swim caused a significantly lower pedal rate with higher torque as compared to the swim-alone sessions. Fatigue manifested later in the lower limb muscles of the cyclists who drafted during the swimming portion of the trial, as measured both by biomechanical analysis and perceived exertion in the cyclists.
(J. Applied Biomechanics, 2005, Vol. 21, No. 3, pp. 297-308; Can. J. Applied Phys., 2001, Vol. 26, pp. 44-54; Int'l J. Sports Med., 2000, Vol. 20, pp. 60-64) |
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To Lose a Pants Size, Run Longer
A new study of over 60,000 active men, ages 18 to 85, finds that distance run per week affects waist circumference more than it does body mass index (BMI). Exercise is associated with reductions in abdominal fat. But the authors also propose that it is the transformation of Type 2b muscle fibers to Type 2a with which exercise has been correlated that reduces waist circumference. Waist circumference has been purported to be negatively correlated with Type 2a muscle fibers and positively correlated with Type 2b—much more so than BMI has been shown to be. Nevertheless, distance running reduces BMI as well. In the present study, those who ran over 64 kilometers (40 miles) per week had 11% lower BMI and 8% smaller waist circumference than those running less than 16 kilometers (10 miles) per week. Simply put, adding distance increases caloric expenditure, and this is an effective means of staving off undesired weight gain as we age. From middle age onward, weight management becomes more difficult. The study, which was conducted by the Life Sciences Division of the Lawrence Berkeley Laboratory in Berkeley, CA, found that BMI and waist circumference increased with age at all running distances. However, the increase diminished by running further. And the heaviest men have the most to gain, so to speak. It was the 90th percentile of weight class that saw the biggest drop in BMI. The difference between this group and the 10th percentile, or leanest among the men, was over two and a half times greater for BMI versus distance run per week than for BMI versus age, which suggests that the difference in the way these two weight-extremes responded is a property of the effect of greater distance and not an attribute of BMI. (Med. Sci. Sports & Exerc., 2005, Vol. 37, No. 8, pp. 1329-1337) |
editorial board Kenneth Cooper, MD |
board of directors Bill Young, President Executive Director: Dave Watt |
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