Clinical Reviews

By Bill Campbell, Ph.D.

"...increasing the protein intake during a low-calorie diet prevented a loss of muscle mass."

Increasing Protein Intake Preserves Muscle Mass in Dieting Athletes

Mettler S, Mitchell N, and Tipton KD. Increased Protein Intake Reduces Lean Body Mass Loss During Weight Loss in Athletes. Med. Sci. Sport. Exer., 2010 February; 42(2); 326-337.

When overweight individuals go on a diet, they not only lose weight, they also lose muscle mass. This is bad news as this decreases metabolic rate or the rate your body burns calories. Plus, athletes who lose muscle mass when dieting only make matters worse by not being able to perform at an optimal level because they also lose functional strength.

So what can you do when you need to lose weight but don't want to lose muscle and strength?! Fortunately, researchers from the United Kingdom have reported that increasing the protein intake during a low-calorie diet prevented a loss of muscle mass.

Specifically, two groups of resistance-trained athletes were placed on a diet for two weeks. Both groups consumed 60% of their normal caloric intake for a two-week period. However, one of the groups consumed a moderate amount of protein (15% of total calories), and the other group consumed a much larger amount of protein (35% of total calories).

At the end of the two-week diet, it was reported that athletes consuming the lower protein diet lost about six pounds of bodyweight, but half of this weight loss was attributed to lean muscle mass. Conversely, the athletes consuming the higher protein diet lost three pounds of body weight but lost less than a pound of lean body mass.

The results of this study further highlight the importance of increasing the protein content of the diet when calories are restricted. Doing so will help maintain lean muscle mass, so you can continue to enjoy elevated metabolic rates and exercise performance.

Nutrient Timing to Improve Calorie Burning

Hackney KJ, Bruenger AJ, Lemmer JT. Timing Protein Intake Increases Energy Expenditure 24 Hours Post-Resistance Training. Med Sci Sports Exerc. 2009 Dec 4. [Epub ahead of print].

We have been repeatedly educated over the past 10 years to make sure we ingest a high-quality protein supplement either immediately before or after our workouts. This accomplishes several things, such as:

• Maximized protein synthesis
• Decreased skeletal muscle protein breakdown
• Decreased hunger over the next few hours

New research will soon be published which highlights another benefit of the timing of protein intake—its positive effects on metabolism.

"Caffeine exerts a greater performance-enhancing (ergogenic) effect when consumed in a pill form as compared to coffee."

Investigators instructed eight resistance-trained subjects to ingest either a whey protein supplement (18g whey protein, 2g carbohydrate, 1.5g fat) or a carbohydrate supplement (1g whey protein, 19g carbohydrate, 1g fat) 20 minutes prior to a single bout of heavy resistance training.

Resting energy expenditure (a measure of metabolic rate) was measured 24 and 48 hours after the resistance training workout. At 24 hours post-workout, resting energy expenditure in response to the whey protein supplement was significantly greater compared to the carbohydrate supplement. The protein supplement elevated metabolic rate by approximately 125 calories per day, while the carbohydrate supplement elevated metabolic rate by only 98 calories per day at 24 hours post exercise.

The authors concluded that timing protein intake prior to heavy resistance training may be a simple and effective strategy to increase energy expenditure by elevating resting energy expenditure the day after resistance training. Increasing resting energy expenditure could help facilitate reductions in bodyfat mass and improve body composition if nutritional intake is stable.

ISSN Stands Up for Caffeine and Performance

Goldstein E, Ziegenfuss T, Kalman D, Kreider R, et al. International Society of Sports Nutrition Position Stand: Caffeine and Performance. Journal of the International Society of Sports Nutrition 2010, 7:5

Caffeine is perhaps the most extensively studied sports supplement on the market. In fact, research on caffeine is very broad, with studies assessing caffeine's effects on endurance, strength, team sports, recovery, hydration, and weight loss. Despite all of the available research, many questions still arise about caffeine. So The International Society of Sports Nutrition recently published a position stand which focused on caffeine and exercise performance.

Many of the common questions people have are addressed in this review. Some of the major points stated in this review are as follows:

• Caffeine is effective for enhancing sport performance in trained athletes when consumed in low-to-moderate dosages, ~3-6 mg/kg (this is approximately 240 to 475 mg of caffeine for a 175-pound individual).
• Caffeine exerts a greater performance-enhancing (ergogenic) effect when consumed in a pill form as compared to coffee.
• Caffeine is performance-enhancing for sustained maximal endurance exercise.
• Caffeine supplementation is beneficial for high-intensity exercise, including team sports such as soccer and rugby, both of which are categorized by intermittent activity within a period of prolonged duration.
• Some studies have demonstrated beneficial effects of caffeine ingestion and strength-power performance, while other studies have not demonstrated this. Additional research in this area is warranted.
• Caffeine does not induce dehydration during exercise or any other harmful change in fluid balance that would negatively affect performance.

While caffeine is clearly performance enhancing, athletes and physically active people vary in their response to caffeine—some are very sensitive and prefer to abstain rather than get over-stimulated. Others thrive on a jumbo cup of espresso. Clearly, it is wise to learn through trial and error the amount of caffeine that works best for your body.

"...plan variation in your workouts (including the exercises you perform)."

Smith Machine and Free Weight Bench Press—Which Is Better?

Schick EE, Coburn JW, Brown LE, et al. A comparison of Muscle Activation between a Smith Machine and Free Weight Bench Press. J. Str. Cond. Res. March 2010; 24(3), 779-784.

The bench press is a common exercise performed by both athletes and recreational lifters. It is one of the best exercises for increasing overall upper body strength and power. Due to its popularity, there are many exercise variations and selectorized equipment available for you to choose from.

Two of the most popular lifts used for bench pressing are the traditional free weight bench press and the Smith machine bench press. It is not clear, though, how each of these modes differs in its effect on muscle activation.

Researchers from California State University compared the muscle activation of the shoulder (anterior and medial deltoid) and chest (pectoralis major) during a Smith machine and free weight bench press. There was a significant increase in medial deltoid muscle activation in the free weight bench press as compared to the Smith machine bench press. There was no significant difference in muscle activation for the pectoralis major or anterior deltoid.

The investigators stated that the free weight bench press is a better selection than the Smith machine due to the role the medial deltoid plays in shoulder joint stability. Sports such as basketball, baseball, tennis, hockey, and volleyball include movements that require deltoid strength and stability about the shoulder joint.

While the results of this study were in favor of the traditional free weight bench press, it is important to not overlook the principle of periodization—which states there should be planned variation in your workouts (including the exercises you perform).

The take-home message here is that the traditional free weight bench press is the better choice (as compared to the Smith machine), but do not take this too far and solely use this great exercise for every single chest workout. Variation is key!

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