Highlights of the 1997 American College of Sports Medicine Meeting

Looking for the latest information on sports-enhancing nutrients? You'd have been in heaven at the annual meeting of the American College of Sports Medicine. Leading researchers from around the world presented their latest sports nutrition findings. From research on creatine increasing lean body mass and investigations on beta-Hydroxy beta-methylbutyrate (HMB) that increase strength to reports on chromium to help with fat loss--these scientists covered it all.

At the four-day conference there were more than 250 seminars, and the results of 1,706 new sports science studies were announced. On May 29 Nutrition Science News made the pilgrimage to this sports nutrition mecca in Denver, Colo., to hear the latest findings and to update you on breaking research. We reviewed and sifted through them all to report on those you might find most pertinent, or just plain interesting. Read on for a quick tour through the latest discoveries from the leading international laboratories and research centers.

HMB And Endurance Cyclists A study out of Wichita State University in Wichita, Kan., by Michael Vukovich, Ph.D., investigated the effect of HMB on maximal oxygen consumption (VO2 max) in endurance-trained cyclists--with the goal being increased VO2 max and endurance time to the point where athletes reached exhaustion. Eight cyclists randomly completed three supplementation periods. Each period was two weeks in duration, followed by a two-week washout period. Supplements were 3 g/day HMB, 3 g/day leucine (LEU) and 3 g/day placebo (control). Prior to and following each supplementation period, subjects completed a VO2 max test.

Two weeks of HMB supplementation resulted in a significant increase in VO2 max (pre-test was 4.57 L/minute; post was 4.75 L/minute--a 4 percent increase). VO2 max was unaffected by supplementation with leucine (pre 4.70 L/minute; post 4.61 L/minute--a 1.9 percent decrease) or the control (pre 4.71 L/minute; post 4.60 L/minute--a 2.5 percent decrease). In addition, HMB supplementation resulted in a significantly greater time to reach VO2 max, whereas leucine and the control did not affect this time (HMB: pre 21.9 minutes, post 22.7 minutes; LEU: pre 22.2 minutes, post 21.6 minutes; control: pre 22.4 minutes, post 21.6 minutes). The researchers concluded that HMB supplementation may have positive effects on performance by increasing VO2 max and endurance time to exhaustion. Up to this point, research showed increases only in the performance of strength-trained athletes.

Creatine, Glucose And Electrolytes Creatine supplementation is reported to increase total body weight and/or muscle-mass weight in trained individuals. In addition, recent studies indicate that glucose, sodium and taurine may enhance creatine uptake. Robert Kreider, Ph.D., and colleagues from the University of Memphis in Tennessee, and Experimental Applied Sciences of Golden, Colo., a supplement producer, undertook a study examining the effects on body composition of the supplement Phosphagen HPTM containing glucose, taurine and electrolytes.

In a double-blind and randomized manner, 25 NCAA Division IA football players were match-paired and assigned to supplement their diets for 28 days with either a supplement containing 99 g/day of glucose (equivalent to 400 calories), 3 g/day of taurine, 1.1 g/day of the electrolyte disodium phosphate, and 1.2 g/day of the electrolyte potassium phosphate or with Phosphagen HPTM plus additional 15.75 g/day of creatine monohydrate.

Subjects' training consisted of five hours/week of resistance training and three hours/week of agility/sprint training. Total body weight and body composition measurements were assessed on days 0 and 28 of supplementation. Results showed that whole body weight significantly increased by 2.2 kg and muscle weight increased by 2.43 kg in the creatine group, while whole body weight only increased 1.34 kg in the other supplement group and muscle weight increased only 1.33 kg. Thus, results indicate that taking creatine with glucose, taurine and electrolytes during training promoted greater gains in body weight and muscle mass in comparison to taking glucose, taurine and electrolytes alone--even when the latter included an additional 400 calories of energy to fuel the muscles.

While it is known that extra calories are needed during hard training to develop more muscle mass, this study shows the synergistic effect of adding creatine to carbohydrates for significant increase in muscle mass compared to just adding calories.

In yet another creatine study, Mary Ferreira, M.S., and her coworkers from the University of Memphis, along with Experimental and Applied Sciences, examined strength and sprint capacity. Using the same group under the same parameters as above, subjects performed a maximal repetition test at 70 percent of their one repetition max on both the bench press and upright squat to determine lifting volume (reps x weight lifted). In effect, the test counted how many times subjects could lift something that weighed 70 percent of the heaviest weight they could lift one time. In addition, subjects performed 12 six-second sprints on a computerized cycle ergometer with 30 seconds of rest between sprints to assess anaerobic capacity.

Results revealed that maximal lifting volumes in the bench press had significantly increased on day 28 over baseline values in the creatine group (supplement group: -20 kg; creatine group: -222 kg ), while squat lifting volumes were not statistically significant in their differences (supplement group: 228 kg; creatine group: 284 kg). For the sprints, anaerobic capacity was generally greater during the initial six sprints in the creatine group, while differences among groups dissipated thereafter. These results confirm that taking creatine with glucose, taurine and electrolytes during training promoted greater gains in upper extremity lifting volume and sprint capacity than glucose, taurine and electrolyte ingestion alone.

Assessing the Zone Diet The diet recommended in The Zone by Barry Sears, Ph.D., uses an exchange-type system with three kinds of foods: protein (PRO), carbohydrate (CHO) and fat (FAT). Serving sizes, referred to as "blocks," are theoretically set so that one protein block = 7 g PRO, one carbohydrate block = 9 g CHO, and one fat block = 1.5 g FAT, translating to a diet that theoretically provides 30 percent PRO, 40 percent CHO and 30 percent FAT as percentages of energy intake. C.A. Titchenal, Ph.D., and associates from the University of Hawaii in Honolulu, using computer analysis of the recommended foods in Appendix C of The Zone, showed that following the Zone diet block system resulted in a diet that actually provided approximately 35 percent, 34 percent and 31 percent of kcal from protein, carbohydrate and fat respectively. The composition of the blocks (range, mean) is: 4.2 to 16.3 g, 7.6 g protein per PRO block; 5.4 to 20.1 g, 9.8 g carbohydrate per CHO block; and 0.3 to 4.4 g, 1.7 g fat per FAT block.

Energy intake for a moderately active 70 kg (154 pound) male (15 percent body fat) is approximately 1,660 kcal/day, or about 50 percent of the energy needs of the same size active athlete, as determined by standard formulas. Compared to traditional sports diets, the Zone diet is proportionately very high in protein, low in carbohydrate, moderate in fat and low in energy content (as determined by overall calories). If this diet is consumed in amounts adequate to meet an athlete's energy needs, protein intake can be excessive at more than five times the RDA (4 g/kg). Thus, researchers concluded that the effects of long-term consumption of these levels of protein are not clearly established.

Sports Drinks And Strength Previous research demonstrates a positive effect of magnesium (Mg) on strength gains in untrained subjects. A study out of Western Washington University by L. Brilla, Ph.D., and colleagues evaluated the effect of a Mg-fortified sports drink (independently tested at 196 mg of Mg) versus a similar sports drink without Mg fortification on strength in 32 collegiate football players during six weeks of spring practice, when the players typically perform intense strength training. Subjects were randomly assigned to drink one of the two sports drinks in a double-blind fashion, consuming the drink prior to and following daily workouts. Testing was done pre- and post-treatment on the following criteria measures: three-day dietary analysis to assess Mg, hydrostatic weighing for fat and lean mass (body composition), and a one repetition max test in the bench press and squat.

Pooled dietary data was analyzed, and no significant differences between treatment groups were found. There were also no statistically significant differences between groups. However, when the 6 low-Mg subjects (Mg intake <7 mg/kg/day) were compared to the 22 higher Mg subjects (Mg intakes >7 mg/kg/day), a significant difference was demonstrated in bench press strength gains for the high-Mg group.

Overall, magnesium fortification was ineffective in eliciting body composition or strength gains in football players. However, the researchers noted that when subjects were grouped by levels of Mg intake, the high group gained more strength in the bench press. The authors point out that these differences may be attributed to magnesium's role in protein synthesis.

Carbohydrates, Chromium And Fatigue Evidence is increasing that carbohydrate-electrolyte drinks (CE) can decrease fatigue during intermittent, high intensity exercise. Chromium (Cr) may increase the ergogenic effects of CE by enhancing insulin action and aiding in muscle glucose/glycogen metabolism. Jim Davis, Ph.D., and his research team from the University of South Carolina in Columbia, studied the effects of carbohydrate-electrolyte drinks, with and without chromium, on fatigue during intermittent, high-intensity shuttle running. Eight male subjects performed three separate trials. Treatments: CE drink, CE drink + Cr, or flavored water placebo (P), were given in a double-blind manner. Chromium (200 ug) or placebo was given one hour before and immediately before exercise. Each trial consisted of five 15-minute bouts of shuttle running (walk, sprint and run at 95 percent and 55 percent VO2 max), separated by three-minute rests, followed by a shuttle run to fatigue (95 percent and 55 percent VO2 max).

CE and Ce+Cr recipients ran longer than the P-group (11.2 minutes and 11.1 minutes vs. 8.5 minutes) in the fatigue test. Blood glucose levels were higher in CE than P trial groups through 45 minutes of exercise and higher than CE+Cr through 30 minutes. There was no significant difference in blood insulin levels among the groups. Free fatty acid levels were higher in the P group than in both CE and CE+Cr at 75 minutes and at fatigue. Blood lactate levels were not different among groups. Heart rate was highest in the P trial group at all time points.

These data support the performance benefit gained by drinking carbohydrate and electrolyte drinks prior to exercise that imitates various sports. Although some suggestion of increased insulin action was found with chromium supplementation, performance was not affected.

Edmund R. Burke, Ph.D., is an associate professor of biology at the University of Colorado, Colorado Springs, as well as a lecturer and co-author of Training Nutrition. Burke is also director of sports sciences for the U.S. Cycling Team.

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