Newsletter Article

MAXIMIZING RESISTANCE TRAINING WITH SUPPLEMENTATION
By Matthew W. Hulver, PhD, CSCS, Post-Doctoral Fellow, East Carolina University and
John P. Thyfault, MS, CSCS, Doctoral Candidate, University of Kansas

Resistance training, an important component of most athletic conditioning programs, improves athletes’ muscular strength and size; it also increases the concentration of hormones and growth-promoting agents in the body that contribute to that improvement. Post-workout supplementation has been suggested as a potential method of increasing hormones in the body improving recovery and potential muscle growth.

There are two classifications of hormones that alter muscle growth¯anabolic and catabolic. Anabolic refers to the process of building or synthesizing tissue, and catabolic refers to the process of degradation or breakdown of tissue. For example, when someone is said to be in an anabolic state, muscular growth is occurring. If someone is in a catabolic state, muscle is being broken down. The major anabolic hormones in the human body are growth hormone, testosterone, insulin-like-growth factor I (IGF-I), and insulin. The major catabolic hormone is cortisol.

Hormones

Growth hormone is responsible for bone, cartilage, and muscle growth.
Testosterone interacts with the cell nuclei and increase protein synthesis.
IGF-I is responsible for inducing protein synthesis in bone, cartilage, and muscle.
Insulin’s primary function is to stimulate cells to absorb carbohydrates and amino acids which produce energy and build protein.
Cortisol stimulates the breakdown of stored energy such as carbohydrates, fat, and protein. Cortisol release is caused by stress (exercise, fear or anxiety) or when carbohydrate levels in the blood are low and the body cells need energy.

Table 1.
Hormones: their respective release sites, target tissues, and principal effects

Hormone	Release Site	Target Tissue	Principal Effects
Growth Hormone	Pituitary gland	Bone, cartilage, and skeletal muscle	Protein synthesis
Testosterone	Testicles and adrenal glands	Skeletal muscle	Protein synthesis
Insulin-like-growth factor I (IGF-I)	Liver	Bone, cartilage, and muscle	Protein synthesis
Insulin	Pancreas	Skeletal muscle	Stimulates absorption of carbohydrates and amino acids for energy production; protein synthesis(limits protein degradation)
Cortisol	Adrenal glands	Skeletal muscle	Protein degradation

Resistance Training and Hormones
The majority of research on anabolic hormones focused on growth hormone, IGF-I, and testosterone, all of which increase in concentration as a result of resistance training. The effect resistance training has on concentrations of these hormones in the blood is dependent on the type of resistance training program. Two common types of resistance training are power lifting and bodybuilding. Research shows that a bodybuilding program produces greater increases in growth hormone, IGF-I and testosterone post-workout when compared to a power lifting program.

Dietary Considerations for Resistance-Trained Athletes
A balanced diet in conjunction with a resistance training program aids the muscle building process. Many athletes do not eat enough calories throughout the day to properly build muscle tissue. To increase size and strength, athletes must consume more calories than the body burns throughout the day. Excess calories are used for building muscle tissue.

Potential Benefits of Post-Workout Supplementation
Recently, researchers examined the effects of beverages containing carbohydrate alone and/or carbohydrate and protein consumed immediately following resistance training exercises. The consumption of a carbohydrate or carbohydrate-protein supplement immediately or up to one hour after exercise significantly restores muscle glycogen levels. Increasing the rate glycogen is restored may benefit an athlete when he/she is training more than once a day or training late in the evening and early the next morning.

The consumption of a carbohydrate or a carbohydrate-protein mixture following resistance training stimulates an increase in blood insulin levels. The increased insulin release is primarily stimulated by carbohydrate intake, but protein intake also shows a slight stimulatory effect. Insulin stimulates glucose and amino acid transport into the muscle, as well as limiting protein breakdown. If insulin levels are raised immediately following a resistance training session, the protein breakdown could be slowed; therefore, magnifying the effects of protein synthesis and creating an environment for muscular growth. The effects of resistance training may be enhanced by post-workout carbohydrate and protein supplementation creating an increased anabolic environment.

The presence of an increased level of amino acids in the blood stream following consumption of a protein supplement and resistance exercise may contribute to an increase in protein synthesis. In fact, protein intake immediately after resistance training, instead of later, may be more essential for muscle growth.

Cortisol is released in high amounts during and after resistance exercise due to the increased level of stress put on the body and a decrease in blood glucose concentration. If blood glucose levels are maintained or quickly restored after a workout by consuming a carbohydrate beverage, cortisol release can be reduced. Not only does nutritional supplementation increase the amount of anabolic hormones released following a workout, it may also decrease the release of cortisol. These effects allow for an enhanced anabolic environment.

The optimal amount or type of nutrient to be consumed after a workout has not been determined, but based on the existing knowledge, post-workout supplements should supply a 2.5 to three-to-one ratio of carbohydrate to protein. Various drinks, mixes and shakes available on the commercial market can be quickly consumed following a workout, and a liquid supplement is absorbed quickly and allows the body to use nutrients at a more rapid rate. However, a quick meal also provides similar benefits. The key is for athletes to consume nutrients immediately following a workout to obtain improved results from training.

An athlete’s nutritional intake plays a crucial role in the development of muscle size and strength in response to resistance training. See Table 2 for a summary of the general effects of post-workout supplementation. A post-workout nutritional supplement can increase the amount of calories consumed during the day. Providing the body with carbohydrates and protein when most needed allows for quicker energy storage restoration, increases the amount of anabolic hormones in the body and decreases the amount of protein breakdown that occurs after resistance training.

Table 2.
Summary of the general effects of post-workout supplementation

Post-workout Supplement	General Effects
Protein	increase protein synthesis increase amino acids in blood stream slightly increase insulin concentrations
Carbohydrate	quickly restores glycogen increase insulin concentrations decrease cortisol concentrations increased tissue absorption of testosterone increased growth hormone concentrations
Carbohydrate and Protein	increase protein synthesis increased amino acids in bloodstream quickly restores glycogen increase insulin concentrations decrease cortisol concentrations increased tissue absorption of testosterone increased growth hormone concentrations

American College of Sports Medicine (http://www.acsm.org)