CLINICAL REVIEWS
By Bill Campbell, Ph.D., Exercise and Performance Nutrition Laboratory, University of South Florida
 Water Workouts to Improve Recovery?
 Water workouts may be an effective way to limit muscle damage from intense workouts. Pantoja PD, Alberton CL, Pilla C, et al. Effect of resistive exercise on muscle damage in water and on land. J Strength Cond Res. 2009 May;23(3):1051-4.
Recovering from intense workouts is just as important as the workout itself when it comes to muscle growth and strength. A novel trend beginning to gain popularity is to engage in concentric-only contractions during the active recovery period (which increases blood flow to promote muscle healing but does not cause the excessive muscle damage that eccentric/negative muscle contractions elicit).
Interestingly, one of the best modes of exercise to elicit concentric-only contractions is sport-specific movements performed under water, but to date, this practice has very little scientific support. So researchers from Brazil undertook a study to compare the effects of resistance exercise in water and on land on blood levels of creatine kinase (a marker of muscle damage).
Nine young men performed three sets of maximum elbow flexion and extension exercise (biceps curls and triceps extensions) in water and on land, separated by two-minute periods of rest. The level of muscular damage (assessed by creatine kinase) was assessed before exercise, after exercise, and at 24 and 48 hours after exercise.
Forty-eight hours after the arm exercises were conducted on land, there was a significant increase in creatine kinase, but no such differences were found 48 hours after the arm exercises were conducted in water.
These results indicate that the water environment influenced the absence of significant muscle damage. This type of exercise protocol may be appropriate for situations in which limited muscle tissue damage is desired—during active recovery from intense workouts.
Meal Composition Affects the Hunger Hormone
 Want to stay full longer? Eat meat! Tannous dit El Khoury D, Obeid O, Azar ST, Hwalla N., et al. Variations in postprandial ghrelin status following ingestion of high-carbohydrate, high-fat, and high-protein meals in males. Ann Nutr Metab. 2006;50(3):260-9.
Ghrelin is a hormone produced in the stomach and pancreas and is associated with stimulating hunger. Ghrelin levels are elevated before meals and suppressed after meals. In fact, ghrelin is referred to as the circulating hunger hormone. The lower the plasma levels of ghrelin, the less hungry an individual will be. If ghrelin levels are high, a ravenous monster emerges!
Researchers from Beirut conducted a study to investigate the response of ghrelin after feeding meals of various macronutrient composition in healthy adult males. All subjects received, on separate occasions, a high-carbohydrate, a high-fat, and a high-protein meal. Blood samples (for the purpose of measuring ghrelin levels) were collected before and 15, 30, 60, 120, and 180 minutes following the ingestion of each meal.
After each meal, ghrelin levels were suppressed. However, ghrelin levels remained significantly lower three hours following the high-protein meal as compared to the high-carbohydrate and high-fat meals.
This is a significant finding, as it provides an explanation for previous observations, showing that high-protein diets were satiating for a longer duration than high-carbohydrate and high-fat meals. A practical application to take from this study is to make sure that each meal you ingest contains a hefty amount of high-quality protein.
High-Protein Diets for Longevity?
 High-protein diets are associated with long-term beneficial effects to help you live a longer and healthier life! Meng X, Zhu K, Devine A, et al. A 5-Year Cohort Study of the Effects of High Protein Intake on Lean Mass and Bone Mineral Content in Elderly Postmenopausal Women. J Bone Miner Res. 2009 May 6.
There is plenty of research available to demonstrate that relatively higher protein diets in healthy, young, exercising individuals are correlated with lean body mass and certain performance outcomes. However, clinical trials investigating the long-term effects of high dietary protein intake on muscle and bone structure in the elderly are not clear.
A cohort study that tracked elderly women addressed this issue over a five-year period. A total of 862 community-dwelling women aged approximately 75 years provided baseline data including nutrient intake assessed by a food frequency questionnaire.
Five years after providing their protein intake, three variables were assessed: upper-arm muscle area, body composition, and bone mineral content (a measure of bone density).
Not surprisingly, there were positive correlations between baseline protein intake and whole body and upper-arm lean mass as well as bone mineral content (meaning that those women who ingested more protein had greater amounts of lean muscle mass and a greater level of bone mineral content). Specifically, women ingesting higher amounts of protein (greater than 87 grams/day) experienced a six percent higher lean body mass and a six percent greater bone mineral content in comparison to those women ingesting the lowest amounts of protein (less than 66 grams per day).
This study demonstrates that a high protein intake is associated with long-term beneficial effects on muscle mass and size and bone mass in elderly women. It also adds to the evidence that high-quality protein intake is beneficial for all age groups.
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