The science of post-workout supplementation

In this age of complex supplementation, the fundamentals of sports nutrition have been forgotten. Simply put, to gain mass one must remain in an anabolic state. The off-season is often a time that focuses on strength gains and hypertrophy. Hypertrophy is an essential step in developing greater strength because in the most basic equation, strength correlates to the cross-sectional area of ​​the muscle. The easiest way to achieve a consistent anabolic response is through a properly timed intake of nutritionally balanced meals.

A post-workout drink is optimal for providing a balance of protein and carbohydrates, as well as providing the added benefit of improved hydration status. The continued 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 catabolize (“break down”) for energy, essentially robbing you and your muscles of all the hard work and growth previously accomplished. Energy consumption immediately after exercise avoids a delay in the delivery of energy substrates to the depleted muscle cell and is therefore an important method of remaining anabolic.

Post-exercise feeding can reduce protein breakdown 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 the muscles is also due to an increase in insulin.

Carbohydrates should not be left out of the post-exercise drink because they are necessary to provide the “spike” of insulin and are an essential energy source for the recovery process. Consuming a mixed carbohydrate and protein drink after training is much more anabolic than consuming just 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 after training (MacDougall et al., 1995). Nutrient intake within this time period has important implications for training adaptations. The protein recommendation for experienced strength athletes is ~1.7 g/kg, while novice trainers may need more.

Requirements may transiently increase with increasing intensity or volume of activity (up to ~2 g/kg) and especially for athletes involved in both strength and speed activities. Resistance exercise also creates an increase in protein requirements of up to 1.6 g/kg/day due to increased protein catabolism during exercise. To help meet these requirements, supplements must contain at least 20 grams of protein per serving.

The carbohydrate component should consist of high glycemic index simple carbohydrates due to their rapid absorption into the bloodstream and rapid delivery to muscle cells (Burke et al., 1993). Increased cellular sensitivity to insulin after exercise provides rapid intracellular delivery and transport of glucose and creatine.

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

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

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

People who often complain of an inability to gain weight are simply not consuming 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 those who gain weight with difficulty. Work hard, stay harder and stay anabolic. Post-exercise supplementation is essential to enhance the anabolic environment and limit the potential for exercise-induced catabolism. These extra calories are welcomed by the hard gainer for use in growth and repair.

A drink after exercise also prevents dehydration since any weight loss after 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 more beneficial after exercise.

Other factors demonstrate the superiority of meal replacements over whole foods in post-exercise condition. Athletes are often tired and don’t have the energy to prepare food or don’t have an appetite for whole foods. Finally, access to food can 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, LM Nutrition for post-exercise recovery. Aus. J.Sci. and Med. 29: 3-10, 1996.

Burke, LM, GR Collier, and M. Hargreaves. muscle glycogen storage after

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

Costell, DL, DD Pascoe, WJ Fink, RA Robergs, SI Barr, and D. Pearson. unmatched

Muscle glycogen resynthesis after eccentric exercise. J.Appl. Physio 69: 46-50, 1990.

Ivy, JL, MC Lee, JT Brozinick, Jr., and MJ Reed. Muscle glycogen storage after

different amounts of carbohydrate intake. J.Appl. Physio 65: 2018-2023, 1988.

MacDougall, JD et al. The time course for elevated muscle protein synthesis after

heavy resistance exercise. They can. J.Appl. Physio 20: 480-486, 1995.

Roy, BD, MA Tarnopolsky, JD MacDougall, J. Fowles, and KE Yarasheski. Effect

of the timing of glucose supplementation on protein metabolism after resistance training. j

Physio application. 82:1882-1888, 1997.