Muscle Retention with High Training Volumes: Advanced Nutrition Strategies

Is it possible to maintain muscle volume while endurance training at a high volume? Absolutely. Here's what you need to know.


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Have you ever been concerned you might be losing muscle because of your triathlon training? 

Of course this isn’t the case for everyone: If you’re not very muscular when you start triathlon, you might actually gain muscle from training—especially in places like your quads (cycling!) and your lats and triceps (swimming!). Or if you come from a long history of resistance training (think powerlifting, functional fitness competition, weightlifting), maybe you’re not even concerned about some muscle loss because you’ve got plenty to spare and you just care about getting faster in your new love, the sport of triathlon. But if those two categories don’t sound like you, and you DO care about retaining your hard-earned muscle but also want to perform well in triathlon, this article is for you.

There are a number of reasons for wanting to keep as much muscle as possible while training for triathlon.

  • Strength. If you like being strong and fit for triathlon, more muscle is a necessity.
  • Power on the bike. Some muscle is handy for pushing the pedals hard, though maybe less than you think.
  • Injury prevention, to a point of course. Bodybuilders would probably suffer loads of injuries from lugging around excessive weight in the form of muscle, but for us mortals without a history of professional bodybuilding or elite strength sport performance, a little more muscle is probably good for injury prevention.
  • Healthy body composition for longevity. Being relatively lean and muscular is good for long-term health, both physiologically and orthopedically.
  • Aesthetics. You might just like the way you look with a little more muscle.
  • Bone density. More muscle generally means more force input to your skeletal system. This increases bone density and decreases risk of osteopenia and osteoporosis.

Wherever you fall in terms of your interest or reasons for wanting to maintain muscle while competing well, the nutritional strategies are pretty much the same. 

  1. Increase dietary protein intake
  2. Ensure dietary protein includes complete proteins
  3. Consume consistent “round-the-clock” protein
  4. Intake sufficient daily carbohydrates to match your training requirements
  5. Time carb intake
  6. Bonus: Sleep!

Increase Daily Dietary Protein Intake

Common recommendations for healthy protein consumption fall pretty far short of what is ideal for muscle retention in a person who is endurance training 6-20-plus hours per week. The best research from the last 20 years or so indicates that the protein recommendations for health are largely a “good enough” recommendation rather than “optimal,” not to mention that they tend to assume minimum physical activity levels of the population at large, which wildly underestimates a triathlete’s activity level. With more activity comes more opportunity for muscle damage and need for repair.  

Targeting a bare minimum of 0.6 grams of protein per pound of bodyweight per day is wise. Most folks will benefit from closer to 0.8 grams per pound of bodyweight per day. If you are on the more muscular side of things and would really like to keep it that way, closer to 1.0 grams protein consumed per pound of body weight per day is probably ideal.

Ensure Dietary Protein Quality

With plant-based diets popularity increasing, meat alternative food product availability increasing, and protein supplement diversity at an all-time high, it is becoming increasingly common for folks to be short on particular amino acids if not daily, periodically within a day, especially those amino acids involved in muscle growth, repair, and retention during high-volume training. If you are not averse to meat or dairy, these are both wise inclusions into your diet regularly. (More on that regularity in the next section.) If you prefer a vegan or vegetarian approach, it’s wise to consider supplementing with soy protein powder to meet your daily protein needs, and to consult with an RD or other nutrition expert (read: highly degreed, not the local nutritionist who has products to sell you).

Consume Round-the-Clock Protein

While the claim that “the body can only process 20g of protein at a time” has been resoundingly refuted by the best and brightest in the field of sport nutrition, it probably is still wise to consume protein at several sittings around the clock from waking time to near bedtime in order to maximize its absorption and the incorporation of the amino acids within it into your muscle tissue.  

Intake Daily Carbohydrate Matching Your Training

You may already know that glycogen is an all-important storage form of carbohydrates in your muscle, used for energy in both aerobic and anaerobic performance.

What you may not know is: Intracellular signaling responsible for the growth and retention of your muscle mass and the proteins that make them up is turned up when more glycogen is stored within the muscles.

If you are falling short of daily carbohydrate needs based on your training demands, you are likely incurring depleted glycogen stores. As a rule of thumb, you should consume sufficient carbohydrate daily to replace 100% of the calories burned during exercise. There are exceptions to this rule in cases of desired weight loss and very low-intensity aerobic type training, but they are few and far between. Bear in mind that most wearable technology can be very erroneous in calorie burn estimates. One of the most detailed guides available regarding matching carb intake to daily training is the The RP Diet for Endurance (caveat: I wrote that book).

Timing Carbohydrate Intake

Adequate and appropriate intra-workout and near-workout carbohydrate consumption results in the following:

  1. It allows your blood sugar level to stay high during training, and as a result, motivation and cognitive performance are improved. That means your effort and interest in pushing hard won’t dip.
  2. The increased blood sugar will allow for glycogen storage during training to prepare for the next workout during rest periods. That means when you partially deplete some of your muscles’ stored energy during a workout, it will be slightly replenished before the next. This increases muscular endurance during the workouts themselves.
  3. It serves to provide an immediate carb source for your muscles to call upon after training. As soon as you stop training, your muscles pull all available sugar from the blood stream to replenish their lost stores. The fastest way to do this is to have it in your gut before training even ends.
  4. There is a slight anabolic response due to increased carbs intra-workout, making the protein that you consume post-workout more well-absorbed and effective at preventing post-workout muscle breakdown. 
  5. In cases where there must be two workouts performed within a day, the intra-workout carb supplementation of the first workout and rapid consumption of carbs after training ensures you are re-fueled by the time the next workout starts. Both also prevent chronic glycogen depletion and the muscle catabolism (breakdown) that would result if glycogen depletion were allowed to persist.

Bonus: Sleep!

Sleep loss does the following:

  1. Increases appetite/desire to eat, especially calorie-dense, protein-lacking foods.
  2. Increases storage of fat on trunk.
  3. Increases storage of fat all over.
  4. Causes muscle loss.
  5. Decreases training quality, intensity, and decision-making related to training volume, which can compound #2, 3, & 4 above.
  6. Does NOT inherently cause weight loss or weight gain, but can affect it through #1 & 5 above. If training quality suffers due to lost sleep, and protein consumption decreases and calorie consumption increases, then muscle loss and fat gain are the likely result.

The Keys to Muscle Retention With High Training Volumes

Muscle retention is important to most of us, whether for health or performance reasons. Maximizing muscle retention is straightforward nutritionally: eat enough protein, ideally including meat and dairy, but if not, ensuring reasonable amino acid profiles of your protein selections; consume protein often daily; match your daily calories in training with your daily carb intake; and do so in large part around and during the time of training.  Last but certainly not least, sleep as much as your life schedule will allow. Your muscles will thank you.

Dr. Alex Harrison, a certified USA Triathlon coach, holds a PhD in Sport Physiology and Performance. He is the author of The RP Diet for Endurance, creator of the RP Endurance Macro Calculator, and has authored and contributed to dozens of articles. When he isn’t pumping out training and nutrition plans in his RV-garage-turned-mobile-office, he can be found on his bike, clinging for dear life to his wife’s wheel.