Did you know that protein synthesis varies for athletes depending on whether they are trained athlete untrained? In this article, we will delve into protein synthesis and explore its role in trained and untrained athletes. We will also discuss factors like exercise intensity, nutrient intake, and the diminishing returns of consuming more than .7 grams per pound of protein to build muscle.
Did you know that exercise muscle protein synthesis varies for athletes depending on whether they are trained athlete untrained? In this article, we will delve into protein synthesis and explore its role in trained and untrained athletes. We will also discuss factors like exercise intensity, nutrient intake, and the diminishing returns of consuming more than .7 grams per pound of protein to build muscle.
Proper athletic development and an individualized training program can help athletes reach their full potential. In the United States, the American Heart Association emphasizes the importance of protein intake in reducing the risk of hypertension, heart failure, and stroke for athletes, especially those involved in cardiology and exercise physiology.
Why Protein Synthesis Is Important for Muscle Physiology?
Protein synthesis is essential for muscle growth and repair in the body. Muscle hypertrophy or muscle growth occurs when protein synthesis rates exceed the protein degradation rates. Studies have found that blocking the crucial mTOR pathway reduces protein synthesis and results in muscle atrophy/ muscle loss. [1]
Essential Amino Acids for Protein Synthesis and Muscle Hypertrophy
In the past, trained athletes were recommended to consume BCAA’s to increase muscle protein synthesis, but BCAA’s do not increase protein synthesis [2]. A complete spectrum of essential amino acids (EAAs) is needed to optimize protein synthesis. Research has shown that the ingestion of EAAs stimulates muscle protein synthesis, with a dose-dependent response observed up to a certain threshold (i.e., 10-14 grams). Endurance athletes and elite athletes benefit from EAAs to improve their athletic performance and sports performance.
Leucine and Protein Synthesis
Leucine, one of the branched-chain amino acids (BCAAs) and an EAA, has been identified as a key regulator of muscle protein synthesis. Supplementing with leucine increased muscle protein synthesis rates in both young and elderly individuals, suggesting that leucine plays a crucial role in promoting muscle hypertrophy across different age groups. The optimal dose appears to be around 2-3 grams per meal.[3]
Timing of Nutrient Intake
Much has changed regarding nutrient timing for athletes; we now know that total protein intake is a better driver of gaining muscle than nutrient timing. There might be a small benefit to consuming protein within a specific timeframe around exercise (i.e., the “anabolic window”); the importance of nutrient timing is diminished when daily protein intake is sufficient.
How does protein synthesis differ for Trained athletes?
While research papers are valuable, many studies use untrained athletes and make extrapolations to trained athletes. For example, a recent study recently compared untrained lacto-ovo vegetarian lifters to meat eaters in a 12-week study. The lacto-ovo vegetarian lifters consumed 1.26 g/kg of bw (.5 gram per pound of bw), and the meat eaters consumed 1.6 g/kg of bw (.7 gram per pound of bw). Despite the higher protein intake, the Lacto-ovo vegetarian lifters gained similar muscle. The Lacto-ovo vegetarian lifters gained 1.3 kg of muscle (.6 pounds), and the meat eaters gained (.7 pounds).[4] The key point is that these were untrained athletes. The trained athlete’s protein synthesis response differs from an untrained athlete’s response.
Untrained Athletes have a Greater Increase in Exercise Muscle Protein After Exercise.
In contrast, trained athletes have a unique advantage when it comes to protein synthesis. A higher protein turnover rate requires more protein synthesis to rebuild and repair muscle tissue after intense workouts. Many research studies investigating the effects of protein intake on muscle growth and strength use untrained participants, which can lead to misleading conclusions. Untrained individuals typically experience greater increases in protein synthesis than trained athletes. As a result, if you have been training for several years, you can’t take a study on untrained athletes and justify that you will respond the same way.
A study by Damas et al. reported that mixed muscle protein synthesis, particularly in the first 48 hours after resistance exercise, was threefold greater in untrained subjects compared to resistance-trained subjects. Moreover, myofibrillar exercise muscle protein synthesis was approximately 43% greater in untrained individuals versus resistance-trained athletes 16 hours post-exercise. [5] These findings highlight the importance of using trained subjects in research studies that compare the effects of different protein intakes on muscle size and strength in well-trained athletes.
Determining Protein Requirements for Olympic Athletes: How Much Protein Do Resistance-Trained Men and Women Need?
While protein intake is important for muscle growth, consuming more protein than necessary may not lead to increased muscle hypertrophy. A systematic review and meta-analysis found that the optimal protein intake for well-trained athletes is 1.6 grams per kilogram of body weight (.7 grams per pound of body weight). The study also found that consuming more protein than this did not contribute to additional gains in muscle mass.[6] Similarly, a study by Lemon et al. found that protein intakes above 2.0 g/kg of body weight did not result in greater nitrogen retention or lean body mass gains, indicating that excessive amounts of protein may not lead to additional benefits for athletes.[7]
Considering Individual Factors: Age-Related Differences and Dose-Response Relationship
Age, training status, genetics, and overall calorie intake can influence a person’s protein requirements. For example, older individuals may require a higher protein intake to offset age-related declines in muscle protein synthesis.[8] Protein supplementation positively impacts lean body mass (LBM) in adults and older adults, regardless of intake timing.
The ISSN Guidelines for Protein Intake for Resistance-Trained Athletes
The International Society of Sports Nutrition (ISSN) provides guidelines on protein intake for individuals engaging in exercise and sports activities. According to the ISSN position stand on protein and exercise, the following recommendations are made for protein intake and muscle hypertrophy:
For building and maintaining muscle mass, a daily protein intake of 1.4 to 2.0 grams of protein per kilogram of body weight (g/kg BW) or .6 to 1 gram per pound of body weight is recommended for most exercising individuals.
Protein intake should be spaced throughout the day and consumed in meals containing 20-40 grams of high-quality protein to maximize muscle protein synthesis. This may be particularly important for athletes seeking to optimize muscle hypertrophy.
A protein dose of 0.25 to 0.3 g/kg BW per meal or 25 to 30 grams is suggested to maximally stimulate muscle protein synthesis in both younger and older individuals.
Resistance exercise and other forms of intense physical activity can increase protein requirements, leading to a higher recommended protein intake for those engaging in such activities.
The ISSN acknowledges that individual protein requirements can vary based on factors such as age, sex, training status, and total energy intake.
Conclusion
Protein synthesis is a crucial process for athletes, especially trained ones. It helps in muscle growth, repair, and recovery after exercise. Factors affecting protein synthesis include exercise intensity, duration, nutrient intake, and timing.High school and professional athletes participating in various sports that require agility and power should also pay attention to their protein intake. Proper athletic development and an individualized training program can help athletes reach their full potential. In the United States, the American Heart Association emphasizes the importance of protein intake in reducing the risk of hypertension, heart failure, and stroke for athletes, especially those involved in cardiology.
Olympic and marathon runners also benefit from proper protein intake. Endurance athletes should focus on maintaining their heart rate and cardiac output, which are influenced by factors like stroke volume and physical therapy. DC or direct current electrical stimulation has also been found to improve athletic training for endurance athletes.
References
1 Drummond, M. J. et al. Rapamycin administration in humans blocks the contraction-induced increase in skeletal muscle protein synthesis. J Physiol 587, 1535-1546 (2009). https://doi.org:10.1113/jphysiol.2008.163816
2 Wolfe, R. R. Branched-chain amino acids and muscle protein synthesis in humans: myth or reality? J Int Soc Sports Nutr 14, 30 (2017). https://doi.org:10.1186/s12970-017-0184-9
3 Gwin, J. A. et al. Effects of high versus standard essential amino acid intakes on whole-body protein turnover and mixed muscle protein synthesis during energy deficit: A randomized, crossover study. Clin Nutr 40, 767-777 (2021). https://doi.org:10.1016/j.clnu.2020.07.019
4 Martini, G. L. et al. Similar body composition, muscle size, and strength adaptations to resistance training in lacto-ovo-vegetarians and non-vegetarians. Appl Physiol Nutr Metab (2023). https://doi.org:10.1139/apnm-2022-0258
5. Damas, F. et al. Myofibrillar protein synthesis and muscle hypertrophy individualized responses to systematically changing resistance training variables in trained young men. J Appl Physiol (1985) 127, 806-815 (2019). https://doi.org:10.1152/japplphysiol.00350.2019
6. Morton, R. W. et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med 52, 376-384 (2018). https://doi.org:10.1136/bjsports-2017-097608
7. Lemon, P. W., Tarnopolsky, M. A., MacDougall, J. D. & Atkinson, S. A. Protein requirements and muscle mass/strength changes during intensive training in novice bodybuilders. J Appl Physiol (1985) 73, 767-775 (1992). https://doi.org:10.1152/jappl.1992.73.2.767
8 Moore, D. R. Maximizing Post-exercise Anabolism: The Case for Relative Protein Intakes. Frontiers in Nutrition 6 (2019). https://doi.org:10.3389/fnut.2019.00147
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