The amino acid leucine is of particular importance to female athletes keen to optimise recovery across the menstrual cycle. Leucine is one of the nine essential amino acids the body needs to obtain through the diet. Leucine along with other amino acids, are required for protein synthesis, tissue repair and nutrient absorption.
The demand for protein changes throughout the menstrual cycle. The fluctuations in estrogen and progesterone have a profound effect on muscle turnover and protein synthesis. Amino acids like leucine are harder to access during the high hormonal phase (day 12 to day 23 of a typical 28 day cycle). It is suggested to be harder for females to build and maintain muscle during this hormonal phase making it even more important to ensure adequate intake of essential amino acids during this time.
Strength training including weights or resistance stimulates muscles to take up leucine (and other amino acids) and triggers muscular growth. Leucine can help prevent the deterioration of muscle with age so it is super important for masters athletes to obtain adequate leucine in order to optimise recovery.
The richest sources of bio-available protein including leucine are in eggs, milk, fish, and meats. Milk contains both whey and casein protein. Whey is more easily absorbed and is higher in leucine than casein. Whey is also digested at a much faster rate than casein, ensuring blood leucine levels rise soon after ingestion and triggering protein synthesis responsible for building muscle. Hence why many athletes swear by chocolate milk as their preferred recovery drink. Female athletes need additional leucine to optimise recovery and would benefit from options such as a post-workout smoothie including yogurt, milk, protein powder or almond butter.
Recent research also suggests that the combination of other highly bio-available proteins rich in leucine results in more favourable muscle hypertrophy compared to other proteins such as whole milk protein, casein and soy protein.
Vegans and athletes with dairy intolerance
Athletes who choose to avoid dairy need not feel they are missing out. Interestingly, a recent study found both whey and rice protein isolate administration post-resistance exercise improved body composition and exercise performance with no differences between the two groups when taken in adequate amounts.
Leucine-rich foods
Leucine can also be found in plant-based proteins included including soy, lentils, kidney beans, tofu, quinoa, hummus, rice, and almonds. These plant proteins contain approximately 50% less leucine. Therefore vegan athletes need to pay attention to getting enough high-quality plant proteins that offer the optimal amount of leucine (about 2.5 grams per meal or snack).
Vegans want to consistently enjoy soy, beans, legumes, seeds and/or nuts regularly at every meal and snack. Don’t have just porridge for breakfast; add organic soy milk and walnuts. Don’t snack on just an apple; slather apple slices with peanut butter. A blend of rice and pea protein powders makes a good substitute for whey-based protein powders. Some plant-based protein powders also provide added amino acids, making them a good choice for dairy-intolerant or plant-based athletes.
As a general guide 2 grams of leucine can be found in 120 grams beef, 130 grams almonds, 400 grams tofu, 3 eggs, 600ml cow’s milk or 900ml soy milk, 380 grams lentils, 350 grams kidney beans, 70 grams cheddar cheese, 350 grams yogurt, 27 grams whey protein isolate, 50 grams rice protein powder.
Elite athletes with large volumes of training may struggle to obtain adequate leucine from their diet alone, especially if vegan. These athletes may consider using protein and collagen powders including leucine, isoleucine and valine 30 minutes pre and post-workouts in addition to a diet rich in leucine to optimise recovery.
This table compares the leucine content of plant and animal foods.
| Animal food | Plant food (swap) | Leucine (g) approx |
|---|---|---|
| Eggs, 1 large | Peanut butter, 2 tablespoons | 0.5 |
| Milk, ½ cup | Soy milk, low fat, 1 cup | 0.5 |
| Tuna, 25 grams | Black beans, 1/2 cup | 0.7 |
| Chicken, 60 grams cooked | Tofu, extra firm, 170 grams | 1.4 |
| Cheese, 14 grams | Almonds, 21 grams | 0.3 |
| Beef, 40 grams | Lentils, 1 cup | 1.3 |
We recommend including a variety of leucine rich foods in your diet in order to optimise recovery.
Most women’s daily protein intake should account for 30% of their diet to optimise recovery. A gram of protein per kilogram of body weight is adequate for recreational athletes, while elite athletes may require up to 1.8 grams per kilogram of body weight, especially when competing in power and high-end endurance sports. On lighter recovery days protein intake can be reduced slightly keeping in mind other processes in the body require adequate protein intake (hormones and immune cells for example).
Consuming 20-25 grams of protein within 30 minutes of finishing a session is ideal for optimal recovery while having a protein-rich snack such as a high protein, low-fat yogurts such as YoPro or Chibani Fit at bedtime can boost protein synthesis by 22 %.
When you wake in the morning you are in a catabolic state after fasting for 10-12 hours during the night while sleeping. Having a protein-rich breakfast is really important to optimise recovery, restock your glycogen stores, fuel your daily activities and prevent overeating and sugar cravings later in the day. Great breakfast options to optimise recovery include scrambled eggs on toast or an omelette with sweet potato and veggies, a protein-rich smoothie, porridge with added yogurt or protein powder or scrambled tofu.
About the Author: Kate Smyth is a Sports naturopath, nutritionist and female-centric running coach. She is the founder of the Athlete Sanctuary- a holistic healthcare clinic for athletes of all levels and sporting codes. Kate has a thirst for knowledge with two bachelor’s and a master’s degree under her belt. She has been involved in sports for many decades and competed for Australia in the Commonwealth Games and Olympic Games marathons with a personal best time of 2 hours 28 minutes. For more information visit www.https://https://athletesanctuary.com.au/wp-content/uploads/2023/03/normatec-3-lower-body-system-thumb_720x-1.webp.com.au/wp-content/uploads/2020/05/Seed-Cycle-Blends-scaled-1.jpg.com.au
