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Tuesday, December 15, 2009

Visceral Fat

Visceral fat is the fat around the abdominal organs. Because such fat is under the abdominal muscles, it cannot be detected by pinching the skin over the abdomen. In contrast, subcutaneous fat is located right under the skin and can be detected by a pinch and quantified by using a skinfold-caliper. Unfortunately, visceral fat is the most dangerous kind in that it produces hormones and inflammatory agents. Framingham heart study researchers reported that visceral rather than subcutaneous fat was associated with an indicator of cholesterol deposits in the aorta, the body's main artery.

Fortunately, exercise can have an impact on visceral fat. A study by Gary Hunter Ph.D., of the University of Alabama at Birmingham, showed that, among a group of women who lost an average of 24 lb by dieting, only those who stuck to an aerobic or strength-training exercise program of 40 minutes, twice a week, managed to keep off all of the visceral fat they lost. Those who did not exercise or who quit their exercise programs increased their visceral fat an average of 33% in the year following their weight loss.

Comparing weight training periodization programs

Weight training periodization has been widely recognized by strength and conditioning coaches to be a more effective means of increasing strength than staying with the same combination of repetitions and resistance over an extended period of time. Periodization basically involves making programmed changes from time to time in the number of repetitions performed in each exercise set, along with an increase in barbell weight as repetitions are decreased, and a decrease in barbell weight as repetitions are increased.

Periodization may be of the linear variety, by which the athlete makes progressive changes in the weight/rep combination during every training block of 1 or more weeks. For example the athlete may do 10 reps with a lighter weight for 2 weeks, then 8 reps with increased weight for 2 weeks, then 6 reps with more weight for 2 weeks, followed by 4 reps with even more weight for 2 weeks. A single repetition max lift may then be attempted before returning to the 10-rep scheme. This cycle may be repeated over an extended time period. The athlete generally gets stronger between cycles so that the weight at all repetitions is adjusted upwards, resulting in a continued increase in strength. Even more complex periodization models have been developed by strength coaches. For example, in daily undulating periodization, the athlete may change the repetition/weight scheme within a single week, with other changes occurring over more extended time periods.

A recent article in the Journal of Strength and Conditioning Research (Vol 23, no 9, pp 2437-2442, 2009) entitled, “Comparison between linear and daily undulating periodized resistance training to increase strength” by Prestes et al., compared these two regimens using 3 sets per exercise 4 times per week with 20 subjects in each training group. The linear program used 12, 10, 8, and 6 reps for a week each, repeating the entire cycle 3 times for a total of 12 weeks. The daily undulating program used 12 reps for half a week, 10 reps for the second half-week, 8 reps for the first half of the following week, and 6 reps for the second half-week. This pattern was repeated 6 times for a total of 12 weeks.

Although the results did not reach statistical significance because of individual differences in training response, the average increases in isometric strength (bench press, leg press, and arm curl) were considerably greater for the daily undulating periodization group than for the linear periodization group. This supports previous research showing the effectiveness of daily undulating periodization programs.

Thursday, December 3, 2009

Heavy weight training improves running economy

Previous research has shown that weight-training improved the running economy of distance runners. To further explore this phenomenon, recent research was undertaken to find out if traditional weight training or explosive weight training had different degrees of effectiveness for increasing running economy. An article entitled, "Effects of strength training on running economy" by Guglielmo, Greco, and Denadai of the Human Performance Laboratory, UNESP, Rio Claro, Brazil, published in the International Journal of Sports Med. in January 2009, presented the results of a study. Sixteen well-trained runners engaged in either traditional heavy weight training or explosive weight training, all for 4 weeks on the same equipment. They were then tested while running on a treadmill to see how much oxygen per unit body weight they used to run at a set speed. Only the group that trained traditionally improved in running economy. The observed 7% increase in economy could translate to a marked increase in running speed sustained over a distance. This study demonstrates that weight training can be beneficial for endurance athletes as well as strength and power athletes.