Is casein protein really that slow to digest?

While commonly perceived as slow-digesting, casein isolate's absorption rate (around 6.1g/hr) is faster than some other proteins like soy or egg. Whey isolate absorbs even faster (8-10g/hr). The distinction of casein as 'slow' often comes from comparing it to whey within the milk protein spectrum, rather than against all protein sources.

Can eating fewer meals, like two per day, still promote hypertrophy if protein intake is matched?

While two meals a day can be a viable way to consume adequate protein, evidence suggests that three large protein feedings throughout the day are more effective for promoting hypertrophy. Consuming fewer than three meals might not be optimal for maximizing muscle growth.

Does it matter if I only do one exercise per muscle group for hypertrophy?

For overall muscle size (global hypertrophy), the number of exercises might not make a significant difference if volume and intensity are matched. However, using a variety of exercises can promote more even development across different regions of a muscle.

What type of exercise is best for bone density?

Resistance training is crucial for bone health. The compressive forces generated by muscle contractions, even with moderate intensity loads, stimulate bone remodeling. While high-intensity training might offer a larger stimulus, simply engaging in challenging resistance training that requires significant muscle force appears sufficient for improving or preserving bone mineral density.

Is there research supporting the need for a 1:1 push to pull exercise ratio for shoulder health?

Currently, there is limited direct human research validating the need for a specific push-to-pull exercise ratio or strength ratio to prevent shoulder injuries in a gym setting. While some theories exist, like upper cross syndrome, and anecdotal evidence from athletes suggests benefits, robust scientific data is lacking.

What's an old-school fitness or nutrition strategy that should make a comeback?

The idea of 'physical culture' focusing on general health and resilience, rather than solely extreme physiques or strength feats, is a strategy that could benefit from a comeback. Additionally, the communal and enjoyment-driven atmosphere of gyms from past decades, before the widespread use of headphones, fostered better camaraderie.

Why is Jim Stoppani so much more popular than Stronger By Science?

The discussion suggests that popularity doesn't necessarily equate to quality or correctness, using sarcasm to highlight this discrepancy. The factors contributing to differing audience sizes are complex and not solely based on the scientific rigor of the content.

Are nutrient timing and absorption speed overly emphasized in fitness advice?

Yes, the emphasis on precisely timing nutrient intake and optimizing digestion speed is often overblown. For muscle building, sufficient total protein, adequate leucine, and reasonable digestibility are key. The specific timing and speed of absorption have a diminishing return and are less critical than foundational factors.

What is the 'muscle full effect'?

The 'muscle full effect' refers to the observation that after consuming protein, there's a lag before muscle protein synthesis (MPS) increases. MPS peaks later and returns to baseline even if blood amino acid levels remain elevated. This indicates that MPS does not perfectly mirror amino acid availability over time.

Protein Digestion Speed, Bone Density, Push-Pull Ratios (Episode 79)

Stronger By Science

Sports4 min read79 min video

Mar 24, 2022|15,978 views|375|43

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Key Moments

TL;DR

Protein digestion speed, exercise variety, bone density, and myths in training and nutrition.

Key Insights

Protein digestion speed and absorption rate are less critical for muscle growth than total intake, leucine, and essential amino acids.

Exercise variety may not be crucial for overall hypertrophy but can be beneficial for developing specific muscle regions evenly.

Resistance training, even at moderate intensity, is effective for building and maintaining bone density due to muscle contraction forces.

The concept of balancing compound pushing and pulling exercises for shoulder health lacks strong scientific evidence.

Historical 'physical culture' focused more on general health and resilience compared to current specialized, extreme goals.

Gym culture has become more individualistic, partly due to personal audio devices, potentially reducing camaraderie.

UNDERSTANDING PROTEIN DIGESTION AND ABSORPTION

The episode begins by clarifying misconceptions surrounding protein digestion speed, particularly the idea of 'fast' versus 'slow' proteins. While it's intuitive to assume that rapidly digested proteins lead to better muscle-building outcomes, research suggests this is not the case. The key factors for muscle protein synthesis (MPS) are sufficient leucine and essential amino acid intake, not the speed at which they enter the bloodstream. Casein, often touted as a 'slow' protein, is actually absorbed quite rapidly compared to other protein sources like whole eggs or soy. The rate of digestion and absorption is influenced by numerous factors, making precise management impractical and unnecessary.

THE RELATIONSHIP BETWEEN PROTEIN INTAKE AND MUSCLE GROWTH

The presenters explain the basic model of protein's role in muscle growth: ingesting protein provides leucine and essential amino acids, which signal and enable muscle protein synthesis. This process is temporary and needs re-stimulation. While a peak in blood amino acid levels does initiate MPS, micromanaging these spikes is not beneficial. Studies comparing different protein sources (e.g., whey vs. plant-based blends) show variations in blood amino acid responses, but these do not necessarily translate to superior long-term muscle hypertrophy. The focus should remain on adequate total protein and essential amino acid intake.

EXERCISE VARIETY AND ITS IMPACT ON HYPERTROPHY

Regarding exercise selection, the discussion reveals that while overall hypertrophy might not significantly differ between performing one exercise per muscle group versus multiple exercises (provided volume and intensity are matched), exercise variety can be beneficial for regional hypertrophy. Different exercises can stimulate various parts of a muscle more effectively, leading to more balanced development. For instance, in the triceps, certain exercises might preferentially target the long head, while others target the medial or lateral heads. Thus, variety ensures more even development across the entire muscle.

OPTIMAL STRATEGIES FOR BONE DENSITY IMPROVEMENT

The conversation shifts to bone health, emphasizing that resistance training is crucial for building and maintaining bone density. While research on precise loading frequencies and volumes is limited due to the slow adaptation of bone tissue, the key stimulus is the compressive force generated by muscle contractions. Even moderate-intensity resistance training, using challenging loads for fewer than 20-30 repetitions, produces significant compressive forces on bones, sufficient for remodeling. The idea that high-intensity training is vastly superior for bone density over lower-intensity training is not strongly supported, as muscles generate substantial force regardless of external load.

EXAMINING THE PUSH-PULL RATIO AND SHOULDER HEALTH CLAIMS

Conventional wisdom suggests a need to balance pushing and pulling exercises to prevent shoulder injuries, often citing upper body strength ratios. However, the research in this area is notably lacking. While practitioners like Eric Cressey have anecdotal evidence linking increased pulling exercises to fewer shoulder issues in baseball players, the demands of sport differ significantly from weightlifting. Furthermore, arguments from authority figures like Boris Shaco, whose powerlifters, despite heavy benching, don't show proportionally high shoulder injury rates despite less rowing, contradict this notion. Reasoning by analogy to the quad-hamstring ratio also appears weak.

THE EVOLUTION OF PHYSICAL CULTURE AND GYM AMBIANCE

A look back at 'physical culture' suggests a historical focus on general health, resilience, and holistic well-being, contrasting with today's often extreme specialization and aesthetic goals. The rise of drug culture and visual media may have contributed to this shift. Additionally, gym camaraderie has diminished, partly due to the prevalence of personal audio devices like headphones. This has made gyms feel more individualistic and less communal, potentially explaining the sustained popularity of group fitness activities. The presenters express a desire for a return to a more health-focused, enjoyable, and social approach to training.

ACUTE MPS VERSUS LONG-TERM HYPERTROPHY AND MEAL TIMING

The episode clarifies that acute measurements of muscle protein synthesis (MPS) are not strong predictors of long-term hypertrophy. Short-term MPS studies provide limited insight, especially in untrained individuals or after unaccustomed exercise, as the response is largely driven by repair. Longitudinal studies on actual muscle growth are far more reliable indicators. Regarding meal timing, evidence suggests that three substantial protein feedings per day are more beneficial for hypertrophy than two. However, the benefits of increasing protein feedings beyond three or four per day appear minimal. Maintaining an eight-hour feeding window is recommended for adequate protein distribution.

Mentioned in This Episode

●Supplements

●Software & Apps

●Companies

●Organizations

●Studies Cited

●Concepts

●People Referenced

Approximate Protein Absorption Rates (Grams Per Hour)

Data extracted from this episode

Protein Source	Absorption Rate (g/hr)
Whey Isolate	8-10
Casein Isolate	6.1
Soy Protein Isolate	3.9
Cooked Egg Protein	2.8
Raw Egg Protein	1.3

Common Questions

The speed at which protein digests and its absorption rate are less critical for muscle growth than ensuring sufficient total protein intake and adequate leucine and essential amino acids. While rapid spikes in amino acids can initiate muscle protein synthesis, long-term studies suggest that the overall accumulation of amino acids over several hours is more important than the speed of initial digestion.

Topics

Protein Digestion Exercise Variety Nutrition Strategies Gym Culture Push-pull Ratio Meal Frequency

Mentioned in this video

supplementsoy protein isolate

Mentioned in a table of protein absorption rates, with an approximate absorption rate of 3.9 grams per hour.

locationRottnest Island

A small island off the coast of Western Australia, known for its large population of quokkas.

personYorn Trommelin

Author of a comprehensive article on muscle protein synthesis, discussing the 'muscle full effect' and the temporal disconnect between blood amino acid levels and MPS rates.

conceptquadriceps

The muscles of the thigh, which can show preferential development in specific heads (vastus lateralis, medialis) depending on the exercise chosen.

personJim Stoppani

Fitness personality whose Facebook group has significantly more members than the SBS group, sparking a discussion on the perceived fairness of popularity and the quality of information.

studyWetard and colleagues

Authors of a review paper titled 'Making Sense of Muscle Protein Synthesis: A Focus on Muscle Growth During Resistance Training,' which concludes that acute MPS is not highly predictive of hypertrophy.

studyBrennan and colleagues

Authors of a study comparing whey protein with plant-based protein blends (pea, pumpkin, sunflower, coconut) to assess blood amino acid responses.

conceptfemur

The thigh bone, discussed in the context of compressive forces during exercises like squats and knee extensions, and how muscle contraction, not just external load, generates these forces.

personGrim RE

Listener who asked about the difference between one exercise vs. multiple exercises for hypertrophy and the relationship between push/pull exercises and shoulder health.

studyFabre and colleagues

Researchers who investigated optimal ratios between fast (whey) and slow (milk protein/casein) proteins, finding no significant long-term differences in outcomes.

personSean Noonan

Listener who questioned the difference in Facebook group membership between Stronger By Science (SBS) and Jim Stoppani's group.

media72 Cutest Animals

A Netflix show that sparked a travel recommendation for Rottnest Island due to its native quokka population.

studyWillborn and colleagues

Researchers who conducted a study comparing whey and casein supplementation for body composition changes in female collegiate athletes, finding no substantial differences.

concepttriceps

The muscles of the upper arm, which have different heads (long head, monoarticular heads) that can be preferentially stimulated by different exercises like skull crushers and bench press.

studyMcNaughton

Author of a 2016 study that investigated if individuals with more fat-free mass require more protein to maximize muscle protein synthesis.

supplementcooked egg protein

Has an absorption rate of 2.8 grams per hour, as noted in a table comparing different protein sources.

personAmanda Casimir

Listener who asked about research on optimal loading, frequency, volume, and movement types for building or maintaining bone density.

supplementwhole egg

Considered a slow-absorbing protein source, but studies comparing it to egg whites show no significant difference in outcomes for muscle building.

conceptWolff's Law

A principle stating that bone tissue will adapt to the loads under which it is placed. It underlies the understanding that mechanical stress stimulates bone remodeling.

supplementcasein

Discussed as a protein source for pre-bed consumption, with the common recommendation of slow digestion, but questioning its actual slow absorption rate compared to other proteins.

supplementraw egg protein

Listed in a table with an absorption rate of 1.3 grams per hour, noting that cooking significantly facilitates digestion.

supplementegg whites

Compared to whole eggs, an egg white meal does not show a significant difference in muscle building outcomes.

supplementLeucine