The Science of Post-Workout Supplementation

In this age of complex supplementation, the basics of sport nutrition have been forgotten. Simply put, in order to gain mass one must stay in an anabolic state. The off-season is often a time focusing on strength gains and hypertrophy. Hypertrophy is an essential step towards developing greater strength because in the most basic equation, strength correlates with the cross-sectional area of the muscle. The easiest way to attain a consistent anabolic response is through a properly scheduled intake of nutritionally balanced meals.

A post-workout drink is optimal for providing a balance of protein and carbohydrates plus it provides the added bonus of an improved hydration state. The continuous presence of calories will fuel muscle growth and recovery by supporting protein and glycogen synthesis. Periods of more than 3-4 hours without food can result in a post-absorptive catabolic state.

Muscles are catabolized ("broken down") for energy, essentially robbing you and your muscles of all the hard work and growth previously accomplished. Immediate post-exercise energy consumption prevents a delay in the delivery of energy substrates to the depleted muscle cell and is therefore an important method to remain anabolic.

Post-exercise feeding can reduce protein degradation and increase protein synthesis. Post-exercise caloric intake is also necessary to restore liver and muscle glycogen (energy stores). The benefits of a post-workout drink occur through the hormonal response to insulin and an increase in amino acid uptake by muscles is also due to an increase in insulin.

Carbohydrates should not be left out of the post-exercise drink because these are necessary to provide the insulin "spike" and are an essential source of energy for the recovery process. Ingesting a mixed carbohydrate-protein drink after training is much more anabolic than consuming only a protein shake. This is also an optimal period for creatine supplementation.

Protein provides the building blocks for muscle growth. Protein synthesis increases 50% 4 hours and 109% 24 hours post-training (MacDougall et al., 1995). The nutrient intake within this time period thus has important implications on the adaptations to training. The protein recommendation for experienced strength athletes is ~1.7 g/kg while novice trainers may need more.

Requirements may transiently increase if intensity or volume of activity is increased (up to ~ 2g/kg) and especially for athletes involved in both strength and speed activities. Endurance exercise also creates an increase in protein requirements of up to 1.6 g/kg/day because of the increased catabolism of protein during exercise. To assist in meeting these requirements, supplements should contain at least 20 grams of protein per serving.

The carbohydrate component should consist of simple, high-glycemic carbohydrates because of their fast absorption into the bloodstream and quick delivery to muscle cells (Burke et al., 1993). The increased cellular sensitivity to insulin post-exercise provides for the rapid delivery and intra-cellular transport of glucose and creatine.

Carbohydrate has also been shown to have anabolic properties by helping to prevent protein breakdown through the insulin-stimulated response. The increased insulin levels post-exercise will not result in increased fat storage because skeletal muscle is the primary consumer of nutrients at this time.

Carbohydrates cause glycogen re-synthesis and replace the fuel source previously depleted by your resistance training (Ivy et al., 1988). The dose of post-exercise carbohydrate should be 0.7-1g/kg (Burke et al., 1996). Glycogen synthesis can be impaired by eccentric muscle damage (Costell et al., 1990) but fortunately most resistance training programs incorporate several rest days before the same muscle group is trained again, therefore glycogen depletion is not a big issue in strength training. The highest rates of glycogen re-synthesis occur following energy intake that is within 2 hours of training (Ivy et al., 1988).

Perhaps even more important is the fact that 1g of carbohydrate per kg body weight has been shown to prevent post-exercise protein breakdown (Roy et al., 1997). Therefore optimal energy intake occurs A.S.A.P. (within 30-minutes of training may be best) in order to raise insulin levels (an anti-catabolic hormone). This is extremely important if a second training session is scheduled within 24 hours, such as for individuals training related muscle groups and athletes involved in tournament play.

Individuals that often complain of the inability to gain weight simply do not consume enough calories. A large portion of the sedentary American population has mastered weight gain through inactivity and constant snacking. Although fat weight is not desired, this scenario can be applied to hard-gainers. Work hard, rest harder, and stay anabolic. Post-exercise supplementation is essential for enhancing the anabolic environment and limiting the potential for exercise-induced catabolism. These extra calories are welcomed by the hard-gainer for use in growth and repair.

A post-exercise drink also prevents dehydration as any weight loss following training is due to water loss. A post-exercise drink or meal-replacement can contribute to the recommended intake of 10 cups of non-caffeinated fluids per day. Because there is no difference in energy replenishment between a liquid and solid food source (Burke, 1996), a liquid meal-replacement appears to be most beneficial post-exercise.

Other factors demonstrate the superiority of meal-replacements over whole food in the post-exercise condition. Often athletes are fatigued and do not have the energy to prepare food or do not have the appetite for whole-food. Finally, the access to food may be limited, especially when other priorities demand time and energy and limit the time the athlete has to return to work or home while still consuming adequate calories.

References

Burke, L.M. Nutrition for post-exercise recovery. Aus. J. Sci. & Med. 29: 3-10, 1996.

Burke, L.M., G.R. Collier, and M. Hargreaves. Muscle glycogen storage after prolonged

exercise: effect of the glycemic index on carbohydrate feedings. J. Appl. Physiol. 75: 1019-1023, 1993.

Costell, D.L., D.D. Pascoe, W.J. Fink, R.A. Robergs, S.I. Barr, and D. Pearson. Impaired

muscle glycogen re-synthesis after eccentric exercise. J. Appl. Physiol. 69: 46-50, 1990.

Ivy, J.L., M.C. Lee, J.T. Brozinick, Jr., and M.J. Reed. Muscle glycogen storage after

different amounts of carbohydrate ingestion. J. Appl. Physiol. 65: 2018-2023, 1988.

MacDougall, J.D. et al. The time course for elevated muscle protein synthesis following

heavy resistance exercise. Can. J. Appl. Physiol. 20: 480-486, 1995.

Roy, B.D., M.A. Tarnopolsky, J.D. MacDougall, J. Fowles, and K.E. Yarasheski. Effect

of glucose supplement timing on protein metabolism after resistance training. J.

Appl. Physiol. 82:1882-1888, 1997.

Craig Ballantyne is a Certified Strength & Conditioning Specialist and writes for Men's Fitness, Maximum Fitness, Muscle and Fitness Hers, and Oxygen magazines. His trademarked Turbulence Training fat loss workouts have been featured multiple times in Mens Fitness and Maximum Fitness magazines, and have helped thousands of men and women around the world lose fat, gain muscle, and get lean in less than 45 minutes three times per week. For more information on the Turbulence Training workouts that will help you burn fat without long, slow cardio sessions or fancy equipment, visit http://www.TurbulenceTraining.com