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New Science for Aging Muscle: Recovery for Masters Endurance Athletes

By Michael Scarbrough | Feb. 01, 2016, 6:32 p.m. (ET)

wheyEvery athlete reaches performance plateaus, and as we age, we experience longer recovery and ebbing performance. Is that the inevitable consequence of aging, or is there more we can do? I’d like to share some recent advances in our understanding of aging’s impact on recovery, and challenge your thinking about how you manage protein nutrition for some answers.

Why protein? It plays a vital role in our bodies’ adaptive response to training, transforming hours of sweat into hard-won performance gains. Once considered the domain of strength athletes, emerging research demonstrates protein’s crucial significance for endurance athletes, optimizing sport-specific muscle function. During recovery muscle takes in amino acids from dietary protein to produce more power-generating enzymes and mitochondria and for repairing stressed muscle fibers. Improved metabolic efficiency and muscle renewal creates superior power production for mile-busting endurance. Researchers define this conversion of amino acids into functional muscle proteins as “muscle protein synthesis” (MPS), a process accelerated by exercise and dietary protein, reaching a pinnacle within two hours following exercise.

With aging, our muscle response to exercise remains intact. Unfortunately, protein’s effect diminishes (see Figure 1), reducing our capacity for adaptation to training. In our mid-30s, we begin to lose muscle mass and experience declining performance, a phenomenon associated with our lowered protein response. In spite of our inability to halt aging, recent insights from exercise science provide us with new tools to restore a youthful protein response, increasing MPS and our potential for training adaptation. For many, this represents the greatest untapped opportunity for performance improvement.

figure 1While we are in the early stages of fully understanding the impact of optimal protein nutrition on endurance performance, several recent studies demonstrate significant gains in peak power, time-trial performance and reductions in muscle damage, especially with repeated bouts of intense training in young, trained athletes. Many more studies demonstrate superior gains in muscle mass and strength in power athletes, even elderly non-athletes, with optimal protein use following resistance training. Although ongoing research will continue to refine best practices for endurance sports, the science is clear: Masters triathletes can benefit today by optimizing their response to protein, thereby maximizing the opportunity for performance improvement. Let me show you how with a few simple guidelines — principles that will benefit younger athletes as well.

Figure 1: Muscle protein synthesis (MPS) dose-response to whey protein. MPS increases with higher protein doses until a plateau is achieved. The older group’s response (dashed line) lags far below the younger group (solid line), but eventually approaches a similar plateau at twice the protein dose. Source: Breen and Phillips Nutrition & Metabolism 2011, 8:68.

Take a fast-acting protein immediately after training. Don’t delay more than 30 minutes; let’s consider why. Exercise turns on the cellular machine, elevating MPS up to 50 percent above baseline within an hour. After consuming a quickly digested protein such as whey, amino acids appear in our bloodstream within 20 minutes, peaking simultaneously with the exercise-induced elevation in MPS. If we’ve taken enough protein, it kicks MPS into high gear, tripling the effect from exercise alone! This combined effect boosts muscle’s ability to utilize circulating amino acids, maximizing the adaptive response. Delayed consumption or eating “slow” proteins won’t deliver the surge required within the limited time window following exercise.

Get the right dose of the right protein. To maximize our response, both dose and quality of protein matter. Activation of MPS depends specifically on the essential amino acid (EAA) content of protein. Since EAA content varies widely among proteins, it becomes a critical factor when choosing a recovery protein. As we age, our minimal requirement of EAAs increases to about 10 grams. Comparison of the highest quality proteins reveals whey protein isolate (WPI) provides a superior amino acid profile for stimulating MPS with 10 grams of EAAs in a 25-30 gram serving, and is the fastest acting.

Plant protein supplements, especially blends formulated to improve upon the EAA profile of single plant sources, offer the best alternative for athletes with whey intolerance or vegetarian diets. The best provide an EAA profile similar to whey. However, slower absorption and lower leucine content compromise their effectiveness by comparison. Whatever your protein choice, I highly recommend staying “all natural,” even if it means paying up for a cleaner product.

Looking at Figure 1, you might ask, “Why not take 40 grams of whey? Problem solved.” My primary concern is the rate of protein digestion. Once we exceed our digestive capacity of about 20 grams, we begin to encounter uncomfortable side effects such as gassiness and bloating. We can handle larger servings of “slow” protein digested over several hours, but not similar quantities of “fast” proteins during our two-hour recovery window. This leads us to my next suggestion.

Stick with fast-acting liquid protein supplements including digestive aids. Burgers, fish tacos or other favs after long workouts have their place, just not for initial recovery. Even protein bars are a compromise with less than ideal amounts of EAAs and slower proteins. Liquids help us rehydrate and digest faster; however, not all liquids are equal. We can process and absorb a fast protein like whey at a rate of 10 grams/hour; slow proteins, including all plant sources, and even milk (slower digesting casein), come in at 3-6 grams/hour. To overcome age-resistance, we need the amino acid equivalent from 40 grams of whey within the first two hours. How do we get there? Protease enzymes, the same ones our bodies produce for protein digestion, can double the amount of amino acids absorbed when added to our protein, permitting a lower dose without annoying stomach upset. Look for supplements with more than a “marketing dose” of enzymes to be useful. Hydrolyzed proteins solve the problem differently. Think of these as being pre-digested into easily absorbed smaller peptides and amino acids. Although excellent, these fast-acting supplements are pricier and often have a bitter taste.

Refuel with proteins high in leucine. More than any other amino acid, leucine is critical during recovery. An essential and branched-chain amino acid (BCAA), it is the only amino acid that directly triggers MPS. To activate MPS, leucine must first reach a threshold blood level that increases with age (note the early sluggish response observed in Figure 1). Once triggered, a sustained rise in MPS depends on the availability of all other EAAs. Although older adults respond to 3 grams of leucine, the optimal amount for athletes is likely higher, perhaps as much as 5 grams. Unfortunately, the leucine content in 25 grams of whey falls below our threshold, and plant proteins contain even less. Don’t dismiss the importance of this critical amino acid; either find a recovery protein with at least 3 grams of leucine or combine it with a separate BCAA supplement. You’ll appreciate another notable benefit of recovery proteins with high BCAA content — reduced post-exercise muscle soreness, enabling improved training effort.

Include carbs with your protein, but wait before eating a full meal. Carbs are essential during early recovery for energy and glycogen replenishment, sparing protein for non-energetic roles. Current evidence supports consuming 1.2 grams/kg body weight in the first hour, or 0.8-1.0 g/kg when combined with protein. Blending a protein smoothie with berries, fruits and almond milk is a great solution for adding carbs to protein, but not always an option. I always travel with a shaker bottle for protein and continue exercise fuel for rehydration and immediate carbs when necessary. Again, stay liquid if possible. Continue with a balanced meal of your favorite foods 45-60 minutes later for sustained recovery support, including another 30 grams of protein and additional carbs. Eating a full meal too early dilutes your recovery protein and slows stomach emptying, delaying delivery of amino acids to muscle.

Keep your mojo going with protein throughout the day! Our bodies don’t store protein; muscles are a dynamic reserve of amino acids in a constant state of flux to meet the entire body’s constant demand. We must continually replenish amino acids with dietary protein or risk losing muscle mass and function. Also high in protein content, bone, tendons and ligaments respond to training and depend on protein for building strength and injury prevention.

     1. Include at least 30 grams of protein with every meal, more if you’re vegetarian. A recent study demonstrated a sustained gain of 25 percent in MPS by following this plan compared with the more typical low-protein breakfast and lunch followed by a heavy protein dinner. By eating at least 30 grams of protein with every meal (varies with food to supply ≥10 grams of EAAs), we improve our ability to preserve the muscle adaptations we’ve worked hard to achieve. Include leucine-rich foods in your diet: examples include lean meats, salmon, eggs, Greek yogurt, tofu, hemp seeds, almonds, chia seeds and pinto beans.

     2. Evaluate your daily protein intake. Athletes with active lifestyles require more protein for optimal health and preservation of muscle mass. For endurance athletes, I recommend 1.2-1.6 grams of protein per kilogram of body weight daily. Even more protein may be needed during periods of intense or high volume training, rehab from injury, planned weight loss and/or muscle gain. When warranted, you may safely consider increasing protein intake up to 35 percent of total energy consumption. Consult with your physician or dietician before adopting a high protein diet if you have pre-existing kidney disease or other chronic condition.

Finally, keep it simple! Following these simple guidelines can be a powerful tool when combined with effective training. Yes, there is more we can do to improve performance with age. Optimize recovery nutrition and protein management to overcome aging hurdles — you put in the work, get the most from your effort!

References and Supplemental Reading:
Breen and Phillips: Skeletal muscle protein metabolism in the elderly: Interventions to counteract the ‘anabolic resistance’ of ageing. Nutrition & Metabolism. 2011; 8:68.
Ferguson-Stegall L, et al. Postexercise carbohydrate-protein supplementation improves subsequent exercise performance and intracellular signaling for protein synthesis. J Strength Cond Res. 2011;25(5):1210-24.
Howarth KR, Moreau NA, Phillips SM, et al. Coingestion of protein with carbohydrate during recovery from endurance exercise stimulates skeletal muscle protein synthesis in humans. J Appl Physiol. 2009; 106: 1394-1402.
Katsanos CS, Kobayashi H, Sheffield-Moore M, Aarsland A, Wolfe RR. A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly. Am J Physiol Endocrinol Metab. 2006; 291:E381–7.
Mamerow MM, et al. Dietary Protein Distribution Positively Influences 24-h Muscle Protein Synthesis in Healthy Adults. J. Nutr. 2014; 144: 876–880.
Moore DR, et al. Beyond muscle hypertrophy: why dietary protein is important for endurance athletes. Appl Physiol Nutr Metab. 2014; 39: 987-997.
Margolis LM, Pasiakos SM. Optimizing Intramuscular Adaptations to Aerobic Exercise: Effects of Carbohydrate Restriction and Protein Supplementation on Mitochondrial Biogenesis. Adv Nutr. 2013 Nov 6;4(6):657-664.
Pasakios SM, et al. Effects of Protein Supplements on Muscle Damage, Soreness and Recovery of Muscle Function and Physical Performance: A Systematic Review. Sports Med (2014) 44:655-670.
Phillips SM. A Brief Review of Higher Dietary Protein Diets in Weight Loss: A Focus on Athletes. Sports Med (2014) 44 (Suppl 2):S149–S153
Phillips SM. Dietary protein requirements and adaptive advantages in athletes. Br J Nutr. 2012 Aug;108 Suppl 2:S158-67.
Reidy PT, et al. The effect of feeding during recovery from aerobic exercise on skeletal muscle intracellular signaling. Int J Sport Nutr Exerc Metab. 2014 Feb; 24(1):70-78.
Rowlands DS, et al. Effect of dietary protein content during recovery from high-intensity cycling on subsequent performance and markers of stress, inflammation, and muscle damage in well-trained men. Appl. Physiol. Nutr. Metab. 2008;33:39-51.
Rowlands DS, Nelson AR, Phillips SM, et al. Protein-Leucine Fed Dose Effects on Muscle Protein Synthesis after Endurance Exercise. Med Sci Sports Exerc. 2015 Mar;47(3):547-55.
Michael ScarbroughThomson JS, et al. Leucine-protein supplemented recovery feeding enhances subsequent cycling performance in well-trained men. Appl. Physiol. Nutr. Metab. 2011;36:242-253.
Yang Y, Breen L, et al. Resistance exercise enhances myofibrillar protein synthesis with graded intakes of whey protein in older men. Br J Nutr. 2012;108(10):1780-8.

Michael Scarbrough, M.D. is the founding CEO of SportScience Nutrition,, and a recreational athlete. An expert on protein nutrition during aging, he has had multiple guest TV appearances. He formulated Pr+ A Smarter Whey to optimize recovery for athletes and active lifestyles over 40.

The views expressed in this article are the opinion of the author and not necessarily the practices of USA Triathlon. Before starting any new diet or exercise program, you should check with your physician and/or coach.