PROTEIN AND AMINO ACIDS
Whey Protein Isolate Promotes Greater Gains Than Casein. Recent research has suggested that ingestion of casein (a slow digesting protein) may have a greater impact on protein synthesis and/or catabolism than whey protein (a fast digesting protein).However, a study by Cribb and colleagues1 from Australia contradicts this hypothesis. In a randomized and double blind manner, 13 resistance trained males supplemented their diets with 1.5 grams/kg/day of casein or whey protein isolate while participating in a supervised resistance training program. Results revealed that subjects ingesting whey protein gain more DEXA-determined muscle mass (4.99 vs. 0.81 kg) and lost more body fat (-1.46 vs. 0.19 kg) than subjects consuming casein. No significant differences were observed between groups in gains in strength. Although no control group was incorporated in this trial, these findings do not support contentions that casein supplementation may promote greater training adaptations than whey protein.
Ingesting a High-Protein Diet Increases Availability of Essential Amino Acids. Bolster and associates2 evaluated the effects of ingesting varying amounts of dietary protein on plasma essential amino acids (EAA). In a crossover and counterbalanced manner, five endurance athletes were randomly assigned to ingest a low (1.0 gram/kg/day), moderate (1.8 grams/kg/day) or high (3.6 gram/kg/day) protein diet for four weeks in alternating fashion. At the end of each dietary intervention, subjects performed a 75-minute run at 75 percent of maximal capacity. Markers of protein oxidation were measured after consuming the diets for three weeks. Additionally, plasma amino acid levels were obtained prior to and following exercise. Results revealed protein oxidation increased with increased dietary protein intake (16, 25, and 52 percent for the low, moderate, and high protein diets, respectively) and that availability of EAA (particularly branched chain amino acids) was significantly greater in a dose-related manner. These findings indicate that ingesting high-protein diets may increase protein utilization and availability of EAA. Theoretically, this may help promote an anabolic response to training.
Colostrum Increases Growth Factors. Bovine colostrum (BV) contains growth factors known to promote anabolic responses. However, most of the growth factors are believed to be degraded during digestion in adults due to the presence of various digestive enzymes. Mero and associates3 evaluated the effects of consuming 20 grams/day of BV for two weeks during training on hormonal responses in men and women. The researchers found that BV
supplementation increased insulin-like growth factor-1 (IGF-1) in men and women by an average of 19 percent. Interestingly, women experienced a greater increase in IGF-1 than men and had less of a decline in IGFBP-3 and growth hormone compared to men. These findings indicate that BV supplementation may increase IGF-1 and that women appear to experience greater benefit.
One Protein Bar Won’t Do It! We’ve all read the claims about the superiority of various types of protein. An interesting study presented by Brown and coworkers4 from Ohio State University compared the effects of soy and whey protein supplementation during training. In a double blind and randomized manner, 29 men were assigned to a control group or to ingest one energy bar per day containing either 33 grams of soy or whey protein for nine weeks. During this time, subjects participated in a supervised resistance training program. Results revealed no significant differences among groups in changes in muscle mass or strength. These findings indicate that ingesting one energy bar per day containing soy or whey protein has no effect on training.
Arginine Boosts Growth Hormone Response. Clinical studies have indicated that ingestion of large amounts of arginine may increase growth hormone levels in patient populations. However, attempts to replicate these findings in healthy individuals have been inconsistent due in part to a lack of understanding about dose-response relationships. Researchers at Syracuse University5 examined the dose response of oral arginine supplementation on growth hormone (GH) in eight healthy males. Subjects participated in four experimental trials involving assessment of GH responses every 10 minutes over a five-hour period. In a randomized manner, subjects ingested 0, 5, 9, or 13 grams of arginine 30 minutes after baseline sampling. Results revealed that ingestion of five and nine grams of arginine promoted a significant increase in GH in a subset of subjects who did not experience gastrointestinal distress. The increase was typically observed between 30 and 60 minutes of ingestion. These findings support contentions that oral arginine may augment GH responses.
Aspartate Increases Anaerobic Power. In the early 1980s, several studies reported a potential ergogenic benefit of aspartate supplementation. However, I haven’t seen much research evaluating the potential ergogenic value since this time. Edwards and associates6 evaluated the effects of aspartate supplementation on arm-crank power. In a double blind and randomized manner, 10 trained college water polo players and nine active college students ingested 2 x 12.5 grams of a placebo or L-aspartate 24 hours and one hour prior to performing an exhaustive bout of arm-crank exercise. The subjects repeated the experiment 48 hours later after ingesting the alternate supplement. Aspartate was found to significantly improve time to exhaustion on the arm ergometer by approximately 13 percent in the untrained and trained subjects. Hopefully, these findings will renew interest in aspartate as a potential ergogenic aid.
L-Tyrosine Does Not Improve Performance. Tyrosine has been found to increase dopamine in the brain. Consequently, it has been hypothesized that ingesting tyrosine during endurance exercise may help prevent fatigue. To test this hypothesis, researchers from Brigham Young University7 conducted a double blind, crossover and placebo controlled study to evaluate the effects L-tyrosine on cycling time trial performance. Nine trained cyclists participated in the study. Subjects were randomly assigned to ingest five milliliters per kilogram (ml/kg) of a flavored placebo, the placebo containing 25 milligrams per kilogram (mg/kg) of L-tyrosine, a seven percent glucose-electrolyte sports drink (GES), or the GES with 25 mg/kg of L-tyrosine every 30 minutes prior to and during a 90-minute time trial performed at 70 percent of maximal oxygen uptake. Results revealed that ingesting the GES during exercise improved time trial performance. However, L-tyrosine supplementation had no significant effects on performance.
Protease Supplementation Reduces Muscle Soreness. Non-steroidal anti-inflammatory drugs (NSAIDS) have been reported to reduce post-exercise muscle soreness. More recently, preliminary reports suggested that proteases may possess similar properties. Miller and colleagues8 compared the effects of NSAID and protease supplementation on muscle soreness precipitated by downhill running. Subjects were administered a placebo, 1,000 milligrams of acetaminophen, or two protease tablets (325 mg pancreatic enzymes, 75 mg trypsin, 50 mg papain, 50 mg bromelain, 10 mg amylase, 10 mg lipase, and 10 mg lysozyme) four times per day for four days following downhill running. Isokinetic tests and a number of markers of muscle soreness were monitored 24, 48, and 72 hours after running. Results revealed that torque production was maintained to a greater degree and subjects experienced less muscle soreness in the group ingesting the protease supplement. The researchers concluded that protease supplementation may attenuate muscle soreness and enhance recovery.
EAAs Stimulate Protein Synthesis. Previous research has indicated that ingesting a small amount of essential amino acid (EAA) with carbohydrate stimulates protein synthesis. Some have suggested that this was related more to the carbohydrate than the protein. A study by Tipton and colleagues9 evaluated the effects of ingesting EAA on protein synthesis following resistance exercise. Six subjects performed a single bout of resistance exercise. At one and two hours following exercise, subjects ingested 0.087 grams/kg of EAA. Results revealed that EAA ingestion significantly increased markers of muscle protein synthesis. These findings indicate that EAA supplementation stimulates protein synthesis independent of carbohydrate intake.
CREATINE
Magnesium-Creatine Chelate Improves Performance. It’s well known that ingesting carbohydrate with creatine enhances creatine uptake due in part to modulating insulin levels. Magnesium has also been reported to influence insulin. Two papers at ACSM examined the effects of ingesting creatine with various forms of magnesium on performance. In the first study, Brilla and Colleagues10 evaluated the effects of ingesting creatine with different forms of magnesium on body fluid and performance. In a double blind and randomized manner, 35 active subjects ingested either five grams/day of a placebo, creatine + 800 milligrams of magnesium, or similar amounts of
magnesium-creatine chelate for two weeks. Subjects had body water determined using multifrequency bioelectrical impedance and performed a set of 30 isokinetic maximal knee extension repetitions prior to and following
supplementation. Results revealed that creatine promoted a slight increase in total body water (due to an increase in intra- and extracellular fluid), but that ingesting magnesium-creatine chelate promoted a slightly greater increase in intracellular water (presumably due to greater intracellular creatine uptake). In addition, isokinetic knee extension performance was significantly improved only in the group ingesting five grams/day of the magnesium-creatine chelate. In the second study, researchers from Ohio State University11 found that 10-days of magnesium-creatine chelate (2.5 grams/day) and creatine (2.5 grams/day) supplementation significantly improved bench press endurance in comparison to subjects ingesting a placebo. Collectively, these findings indicate that creatine-magnesium chelate may serve as an effective source of creatine.
Creatine Does Not Affect Muscle Contraction Properties. Early creatine research suggested that creatine supplementation may speed up voluntary muscle contraction time. However, more recent studies have reported limited effects. To further examine this issue, Dr. Roger Harris (a pioneer in creatine research) conducted a study to determine whether creatine supplementation affects involuntary or voluntary muscle contraction
properties.12 In the study, 10 healthy men participated in two practice trials. The subjects were then matched according to performance capacity and randomly assigned to ingest a placebo or creatine (20 grams/day for seven days) in a double blind manner prior to performing a post-supplementation test. The exercise test involved performing a series of maximal voluntary isometric contractions performed at 33 and 66 percent of maximal voluntary contraction capacity. In addition, subjects had their quadriceps electrically stimulated at several levels of stimulation to determine response to involuntary muscle contractions. Results revealed subjects gained about three pounds in response to the protocol. However, no significant differences were observed between groups. These findings indicate that creatine does not appear to alter voluntary or involuntary muscle contraction properties, suggesting the ergogenic benefits are more related to improved energy status of the muscle.
Creatine Does Not Increase Thermal Stress. Creatine has been anecdotally suggested to increase thermal stress and predispose dehydration in athletes. However, studies that have evaluated this hypothesis have found no relationship and/or that creatine supplementation actually prevents dehydration. Two papers were presented that evaluated this relationship. In the first, Graham and colleagues13 evaluated the effects of creatine loading on submaximal exercise performed in the heat. Eight male college students ingested 20 grams/day of creatine or a placebo for three days. The subjects then performed 90 minutes of cycling exercise at 50 percent of maximal exercise capacity in an environmental chamber set at 90 degrees F and 52 percent RH. Subjects donated pre-exercise, post-exercise, and 24-hour recovery blood samples. In addition, heart rate, blood pressure and core temperature was monitored during the cycling trials. The authors reported that creatine did not significantly affect heart rate, blood pressure, plasma volume, or serum potassium levels. However, heart rate and core temperature tended to be higher during the exercise trial following creatine supplementation. In addition, a significant interaction was observed in serum sodium levels. The differences observed in these variables were not reported in the abstract. Nevertheless, the researchers concluded that short-term creatine loading may affect serum electrolyte levels and thermal responses to exercise in the heat. Conversely, Rosen and Whitman14 reported that creatine supplementation (20 grams/day for seven days) had no effect on core temperature, skin temperature, heart rate, blood pressure, urine specific gravity, or changes in bodyweight in women when performing 30 minutes of cycling exercise at 70-75 percent of maximal capacity in a thermoneutral environment.
Creatine Supplementation Improves Running and Cycling Sprint Performance. Critics of creatine supplementation have contended that although creatine may enhance performance in non-weight bearing exercises like cycling, the associated weight gain may negate the potential ergogenic effect in weight-bearing exercises like running. Researchers from Japan15,16 evaluated this contention by investigating the effects of creatine supplementation on repetitive running and cycling sprint performance in 14 male college athletes. Subjects performed 5 x 60 meter running sprints with five minutes of recovery and 5 x 7-second cycling sprints with five minutes recovery prior to and following ingesting a placebo or 20 grams/day of creatine for six days. Running sprint performance was analyzed in 20-meter segments (i.e., 0-20 meters, 20-40 meters, and 40-60 meters). The researchers reported that creatine helped maintain sprint performance during the 20-40 meter and 40-60 meter segments. In addition, creatine supplementation improved cycling power. These findings indicate that creatine supplementation can improve repetitive running and cycling sprint performance in college athletes.
Creatine Phosphate Increases Anaerobic Power. Creatine and phosphate supplementation have independently been reported to increase exercise capacity. However, it’s unclear whether co-ingesting these nutrients may provide added benefit. Eckerson and associates17 evaluated the effects of co-ingesting creatine with phosphate. In a double blind and randomized manner, 30 active females were assigned to ingest a placebo, or four grams of sodium and potassium phosphate with five grams of creatine, or five grams of creatine with 18 grams of dextrose (glucose) four times per day for six days. At 0, 2, and 6 days of supplementation, subjects performed anaerobic sprint tests. Results revealed that power output was increased by 1.1 percent, 13 percent, and 11 percent in the placebo, creatine-phosphate and creatine-dextrose groups, respectively. However, although these changes were impressive, they were not significantly different from the placebo values.
Creatine Decreases Lactate and Ammonia Levels in Swimmers. Another controversy among sport scientists is whether creatine may be beneficial for swimmers. Researchers from Brazil18 evaluated the effects of creatine supplementation on swim performance and metabolic markers of intensity. Twelve swimmers had body composition determined and then performed 12 x 25 meter swim sprints with 120 seconds of recovery. Subjects were then matched and randomly assigned to ingest a placebo or five grams of creatine with 20 grams of carbohydrate four times per day for eight days. Subjects then repeated the body composition and swim sprint test. Pre- and post-exercise blood lactate and ammonia levels were determined prior to each trial. Results revealed that creatine supplementation increased body mass, fat free mass and total body water. Performance times were not significantly affected. However, blood lactate and ammonia (a marker of adenine nucleotide degradation) were significantly lower following creatine supplementation, suggesting greater metabolic efficiency. The researchers concluded that the weight gain observed may have negated the beneficial metabolic effects observed.
Gender Differences. Over the years, there has been some debate about whether creatine supplementation works as well for women as for men. Two papers examined gender influences of creatine supplementation. Buckley and coworkers19 reported that ingesting 6.8 grams/day of creatine for six days (about one third the recommended loading dose) did not improve 3 x 30-second cycling sprint performance with three minutes of recovery between sprints in 10 active females. Obviously, this may be more related to an insufficient intake of creatine than a lack of ergogenic benefit in women. In another study, researchers from the University of Saskatchewan20 reported that creatine supplementation (0.2 grams/kg/day for sox weeks) during a supervised resistance training program promoted greater gains in strength in men and women compared to those ingesting a placebo. However, men who took creatine during training observed a greater increase in muscle mass than women. These findings support previous reports that creatine supplementation can improve training adaptations in women, but that women appear to gain muscle mass at a slower rate than men who take creatine.
Creatine Supplementation During Intense Training is Safe.. Researchers from Arkansas State University (ASU) and the University of Memphis (UM) reported a series of papers investigating the long-term safety of creatine supplementation among athletes.21-23 In the first two studies, the incidence of cramping and injuries treated by the athletic training staff at ASU during 18 weeks of college baseball21 and football22 training/competition was compared to athletes who did not take creatine during training. Results revealed that the incidence of cramping and injuries among creatine users was proportional or lower than athletes who did not take creatine during training. In a related study, researchers from my lab evaluated fatigue and side effect inventories obtained from 100 Division I college football players during training/competition.23 During the study, 43 percent of the athletes ingested 15 grams/day of creatine for five days followed by ingesting an average of five grams/day of creatine during 19 weeks of pre-season and in-season training. Subjects completed a 15-item fatigue inventory and a 17-item health inventory once a week throughout the study. Results revealed that subjects taking creatine during training reported significantly less heart and lung fatigue, a more positive attitude towards training, and felt physically stronger than athletes who did not take creatine. In addition, subjects taking creatine reported more restful sleep and significantly less nasal congestion, coughing, ear
tenderness/throat soreness, muscle cramping and stomach upset in comparison to athletes who did not take creatine. Collectively, these studies add to the increasing body of evidence that creatine is not only safe, but may enhance health status.
THERMOGENIC SUPPLEMENTS
Ephedra/Caffeine Supplements Increase Energy Expenditure. Ephedrine and caffeine (EC) have been effectively used to increase energy expenditure and promote weight loss. However, concerns have been raised over the potential adverse effects on the cardiovascular system. Vukovich and colleagues24 evaluated the effects of ingesting a single dose of 20 milligrams of ephedrine and 150 milligrams of caffeine on heart rate, blood pressure and resting energy expenditure in a group of eight healthy males and females. Subjects reported to the lab, rested for 15 minutes and underwent 30 minutes of baseline testing. Subjects were then randomly assigned to ingest either a placebo or an EC supplement. Heart rate, blood pressure, energy expenditure, and blood fatty acid levels were determined intermittently during a three-hour observation period. Results revealed that, in comparison to the placebo trial, EC ingestion promoted a significantly greater increase in resting heart rate (23 versus nine beats/minute) 60-minutes following ingestion. At three hours post-ingestion, systolic blood pressure (9 versus 2 mmHg) and resting energy expenditure (10.7 versus 4.7 percent) were significantly higher in the EC group. No significant differences were observed in diastolic blood pressure. These findings add to the growing body of evidence that EC supplementation may elevate resting metabolic rate with mild and transient changes in heart rate and systolic blood pressure.
Comparison of Green Tea, Caffeine and Ephedrine. Previous research has indicated that green tea (GT) and EC supplementation increases energy expenditure while ingestion of caffeine alone has few thermogenic effects. However, a paper presented by Arciero and associates25 from Skidmore College (yes, there is such a place) found contrasting findings. In this study, 10 healthy men and women participated in a double blind, placebo controlled, randomized trial to determine the effects of ingesting one oral dose of caffeine (200 mg); green tea extract (270 mg of catechin polyphenols); caffeine (200 mg) with green tea (270 mg of catechin polyphenols); and caffeine (40 mg) with ephedrine (12 mg) on metabolic rate. Subjects had baseline energy expenditure measurements determined and then ingested one of the aforementioned supplements. The thermogenic response to the supplements was then monitored for 120 minutes. Interestingly, results revealed that a single dose of green tea, green tea with caffeine, and EC had no significant affects on energy expenditure. However, a significant increase in resting metabolic rate was observed after ingesting caffeine alone. These findings contrast previous reports indicating that green tea extract and EC possess thermogenic qualities and are rather strange in that metabolic rate was not affected in the green tea with caffeine group, although the subjects ingested the same amount of caffeine in each trial.
Ingesting Herbal Ephedra and Caffeine with Food Does Not Increase Thermogenesis. Supplements containing Ma Huang (herbal ephedra) and caffeine have been reported to possess thermogenic properties. However, food digestion also stimulates thermogenesis. Researchers from Adelphi University26 attempted to determine whether ingesting herbal ephedra or caffeine with a standardized meal increases energy expenditure in comparison to ingesting the food alone. Nine male and female subjects participated in this double blind and crossover designed study. On three occasions, baseline metabolic rate was determined. Subjects were fed a meal containing 250 kcals, or the meal with 670 milligrams of Ma Huang (from Xenedrine RFA-1), or the meal with 600 milligrams of caffeine in a randomized manner. Metabolic rate was assessed for 120 minutes following ingestion of the supplements. Results revealed that metabolic rate was increased in all groups following the feedings, but that there were no significant differences observed among groups. The researchers concluded that ingesting herbal ephedra or caffeine with a meal does not increase thermogenesis above that of the food intake alone.
Comparison of Ephedrine and Herbal Ephedra. Herbal ephedra is considered by many to be the same as synthetic ephedrine. However, an interesting study conducted by Swain and Colker27 compared the pharmacokinetics of ingesting Ma Huang (standardized for 20 milligrams of ephedrine alkaloids) to ingesting 20 milligrams of synthetic ephedrine. Baseline blood samples were obtained and then subjects were fed herbal or synthetic sources of ephedrine. Blood ephedrine levels were determined every three hours during a 12-hour observation period. Results revealed that herbal and synthetic ephedrine ingestion increased blood levels of ephedrine. However, differences were seen in the pattern of response observed. It appeared that herbal ephedrine ingestion degraded to a greater degree but leveled off to a higher level than the synthetic ephedrine. The researchers concluded that the pharmacokinetic responses of herbal and synthetic sources of ephedrine differ and therefore should not be used interchangeably.
ODDS AND ENDS
Andro Increases Testosterone Levels in the Elderly. Most studies that have evaluated the effects of oral androstenedione supplementation have reported limited to no effects on testosterone levels in younger populations.
However, the effects of andro supplementation in elderly populations who may have low testosterone levels remains to be determined. A study by Dr. Bruce Craig from Ball State University28 evaluated the effects of ingesting 300
milligrams/day of androstenedione for seven days on testosterone and estradiol levels prior to and following resistance exercise. The researchers found that andro supplementation increased serum testosterone levels with variable effects on estradiol. These findings suggest a possible beneficial role of andro supplementation for the elderly.
Ketogenic Diets Decrease Power and Endurance. Low carbohydrate diets have become a popular means of promoting weight loss. Although they can be effective, I have warned that it may be difficult to maintain high-intensity training volume on such a diet. Research from the University of Connecticut29 supports this view. In this regard, they monitored the effects of reducing dietary carbohydrate intake from 48 to eight percent for six weeks on exercise capacity in comparison to controls who did not alter their diet. The researchers found that adhering to the ketogenic diet decreased absolute maximal oxygen uptake (-6%), peak and mean muscular power (-8%), and power output during a 45-minute cycling endurance ride (-18%). The researchers concluded that ketogenic diets decrease exercise capacity in part due to a decrease in body weight.
Phosphatidylcholine Improves Recovery from Resistance Exercise. Intense exercise promotes muscle damage, enzyme leakage, muscle soreness and reductions in strength and power. Polyunsaturated phosphatidylcoline (PPC) supplementation has been suggested to help maintain muscle cell integrity and promote recovery. An interesting study from Dr. Bill Kraemer’s lab at the University of Connecticut30 evaluated the effects of repeated bouts of resistance exercise on performance, body composition and recovery. In the study, 18 healthy men ingested a placebo or PPC for three weeks. Subjects then underwent pre-exercise assessments and performed three resistance training sessions (four sets of 10 repetitions on the squat, bench press, bent-over row and shoulder press) with three days of recovery between sessions. Body composition measurements and markers of muscle damage and soreness were monitored prior to, and for 10-days following, the first exercise session. Results revealed that subjects ingesting PPC experienced less evidence of muscle damage and a greater increase in muscle mass (+0.74 versus 0.33 kg) compared to subjects taking the placebo. The researchers concluded that PPC supplementation may have favorable effects on muscle mass accretion and recovery from resistance exercise.
Summary
There were many interesting papers presented at the 2002 ACSM annual meeting related to nutrition and performance. Some studies provide additional support regarding the ergogenic value of various nutrients, some provide new direction for future research, and some confuse the issues. The thing to remember is that recommendations about nutritional supplements and strategies should be based on an overview of the entire body of evidence regarding the performance value of a nutrient and not one study.
source:musculardevelopment.com
