Protein and Leucine: Maximize Your Strength

What do you really need to help support muscle building?

Whether you're an endurance athlete or an athlete focused on power sports, building a solid base of muscle is crucial.

For some athletes, performing their best means losing fat mass to get to a lean, healthy race weight. Without proper nutrition, however, you’ll not only lose fat but muscle mass as well. This could lead to substandard performance because of decreased strength and aerobic capacity. Not ideal.

No matter what your plan entails, the one piece that should never be left out is nutrition. Depending on what phase of training you’re in, your fueling may change to help promote muscle gain and muscle maintenance.

Training your Muscles

Skeletal muscle responds to exercise in a variety of ways.

Endurance training alters muscle cells to be more fatigue resistant, be able to use fats for fuel, and have the capacity for more efficient use of carbohydrate fuels. This means building a sufficient concentration of mitochondria - the fuel-burning powerhouse of muscle cells. These little organelles burn carbohydrates and fat for endurance exercise.

Strength-trained muscles use primarily quick chemical reactions for power rather than carbohydrates or fat. This process also happens in the mitochondria but uses stored adenosine triphosphate (ATP) and creatine phosphate for quick, powerful bursts of energy.

Resistance exercise is a potent stimulant of Muscle Protein Synthesis (MPS), or the building of muscle, and this process is further enhanced by specific nutrients.

This is where leucine comes into play.

What is Leucine?

Leucine is an essential amino acid that is theorized to be the limiting factor of MPS. This means that while all amino acids are necessary to build protein, without enough leucine muscle accretion is not nearly as great as it could be.

The leucine content of different protein sources differs dramatically.

Grams Leucine per 100g product

• Whey Protein Powder: 9.0 g

• Pea Protein Powder: 8.4 g

• Dried Egg White Powder: 6.83 g

• Soy Protein Isolate Powder: 6.78 g

• Casein Protein Powder: 6.65 g

• Dry Nonfat Milk: 3.54 g

• 2 Whole Eggs: 2.17 g

• Dry Black Beans: 1.72 g

• Ground Beef (95% Lean): 1.67 g

• Whole Wheat Flour: 0.89 g

As you can see, whey protein powder (made from the liquid left behind when milk is curdled and the solids [casein] are removed) provides the highest concentration of leucine.

The good news for vegans is that pea protein powder holds a very close second in leucine content with 8.4g per 100 grams.

Leucine: Amount and Timing for Muscle Gain

The above graph, created from a review of nine studies, shows resistance training-induced changes in lean muscle mass using different protein sources, with whey supplementation post-exercise creating the highest gains.

How much protein is needed for muscle gain? And does it need to be evenly distributed throughout the day?

Along with the type of protein, the amount consumed also plays a key role. It used to be assumed from research that taking anything more than 20 grams of protein at a time was inefficient and that more than this would be burned as energy.

However, newer studies are showing that even high doses of protein, even up to 100 grams at a time, can induce muscle accretion long after exercise has ended.

The bottom line with current research is that as long as your total protein intake throughout the day is adequately high, even if it is not distributed evenly, you will build muscle well.

Calculate how much protein you need

According to some research, the maximum amount of protein that can be used to build muscle is approximately 1.6 - 2.2 g/kg/day.

Above this, the excess protein may not help to increase your muscle mass.

When to take protein after a strength workout

Timing your protein supplementation is also important for MPS.

Goal:

• If you are not eating within 3 to 4 hours after a workout, consume at least 20 grams of protein for recovery.

• If you are not for more than 4 hours after a workout, consume at least 40 grams of protein for recovery.
  

So what does this mean for your training?

Training: Strength Phase

During the strength blocks of your training, when muscle accretion is an important factor, focus on getting a higher protein along with adequate calories.

If you won't be eating soon after a strength training session, aim to have 20-40 grams of high-quality protein within the initial recovery hour.

This will help you make the most of your resistance training.

Training: Endurance Phase

During the second half of your season, as time in the gym diminishes and endurance training increases, it’s equally important to focus on the timing of protein and overall fueling and nutrition.

Fuel your workouts with a pre-workout carbohydrate-rich snack, and refuel with a 4:1 or 3:1 ratio of carb:protein recovery drink.

To help maintain muscle mass during this time, get adequate protein throughout the day, but also include a protein shake before bed. This is particularly important if you did not meet your daily protein goals or if it has been at least 3 hours since your last meal. Aim for 20-40 grams of protein.

Nighttime is when the body releases human growth hormone to help rebuild and repair muscles. This is your body’s prime anabolic (muscle-building) time. Having protein before bed may help with the muscle recovery and build process.

Sources

1. Phillips SM, Van Loon LJ. Dietary protein for athletes: from requirements to optimum adaptation. J Sports Sci. 2011;29 Suppl 1:S29-38.

2. Moore DR, Robinson MJ, Fry JL, Tang JE, Glover EI, Wilkinson SB, Prior T, Tarnopolsky MA, Phillips SM. Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. Am J Clin Nutr. 2009 Jan;89(1):161-8. 

3. Macnaughton LS, Wardle SL, Witard OC, McGlory C, Hamilton DL, Jeromson S, Lawrence CE, Wallis GA, Tipton KD. The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein. Physiol Rep. 2016 Aug;4(15):e12893.

4. Tinsley GM, Moore ML, Graybeal AJ, Paoli A, Kim Y, Gonzales JU, Harry JR, VanDusseldorp TA, Kennedy DN, Cruz MR. Time-restricted feeding plus resistance training in active females: a randomized trial. Am J Clin Nutr. 2019 Sep 1;110(3):628-640.

5. Trepanowski JF, Kroeger CM, Barnosky A, Klempel MC, Bhutani S, Hoddy KK, Gabel K, Freels S, Rigdon J, Rood J, Ravussin E, Varady KA. Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese Adults: A Randomized Clinical Trial. JAMA Intern Med. 2017 Jul 1;177(7):930-938.

6. Trommelen J, van Lieshout GAA, Nyakayiru J, Holwerda AM, Smeets JSJ, Hendriks FK, van Kranenburg JMX, Zorenc AH, Senden JM, Goessens JPB, Gijsen AP, van Loon LJC. The anabolic response to protein ingestion during recovery from exercise has no upper limit in magnitude and duration in vivo in humans. Cell Rep Med. 2023 Dec 19;4(12):101324. 

7. Moore DR, Robinson MJ, Fry JL, Tang JE, Glover EI, Wilkinson SB, Prior T, Tarnopolsky MA, Phillips SM. Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. American Journal of Clinical Nutrition 2009;89(1):161-8. doi: 10.3945/ajcn.2008.26401.

8. Witard OC, Jackman SR, Breen L, Smith K, Selby A, Tipton KD. Myofibrillar muscle protein synthesis rates subsequent to a meal in response to increasing doses of whey protein at rest and after resistance exercise. American Journal of Clinical Nutrition 2014;99(1):86-95.

9. Macnaughton LS, Wardle SL, Witard OC, McGlory C, Hamilton DL, Jeromson S, Lawrence CE, Wallis GA, Tipton KD. The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein. Physiol Rep 2016;4(15). doi: 10.14814/phy2.12893.

10. Kim IY, Schutzler S, Schrader A, Spencer HJ, Azhar G, Ferrando AA, Wolfe RR. The anabolic response to a meal containing different amounts of protein is not limited by the maximal stimulation of protein synthesis in healthy young adults. American journal of physiology Endocrinology and metabolism 2016;310(1):E73-80. doi: 10.1152/ajpendo.00365.2015.