What factors influence muscle fiber type distribution?

Muscle fiber types are influenced by genetics, hormones (sex hormones cause subtle average differences between sexes), and training history. Training can cause hybrid fibers to differentiate into more pure Type 1 or Type 2A fibers, depending on the type of exercise (endurance vs. resistance training).

Can functional tests determine my muscle fiber type dominance?

No, functional tests like rep max tests (e.g., Charles Poliquin's 80% 1RM test) are not reliable predictors of an individual's actual muscle fiber type distribution. Accurate determination requires invasive methods like muscle biopsy or specialized lab equipment like proton magnetic resonance spectroscopy.

Does training specifically for certain fiber types improve muscle growth?

Based on current research, it doesn't appear necessary to train specifically for Type 1 vs. Type 2 fiber growth. Both low-load and high-load training seem to effectively grow both fiber types. The idea that specific training styles predominantly stress only one fiber type for growth is not strongly supported by evidence.

Are artificial sweeteners linked to an increased risk of cancer?

A recent NutriNet-Santé study suggested an association between artificial sweetener consumption (particularly aspartame and Ace-K) and increased cancer incidence. However, the findings are not consistently robust or generalizable, and previous studies from the same cohort showed sugary drinks, but not artificially sweetened beverages, were linked to cancer risk.

What is the absolute risk of cancer associated with artificial sweeteners from the NutriNet-Santé study?

While relative risk of cancer was reported to increase by approximately 20% for artificial sweetener consumers in the NutriNet-Santé study, the absolute increase in incidence was small. For non-consumers, it was 3.1%, for low consumers 3.9%, and for high consumers 3.2%. This translates to a small absolute increase, and even the low consumer group had a slightly higher incidence than high consumers in raw data.

How do nitrates from plants differ from nitrates in cured meats regarding cancer risk?

Plant-derived nitrates, consumed with fiber and antioxidants, are generally considered healthful and are associated with a reduced risk of gastric cancer. In cured meats, nitrate salts break down into nitric oxide and subsequently can form nitrosamines (especially when cooked at high heat), which are suspected carcinogens. The context of ingestion, particularly the presence of other compounds, dictates the health outcome.

Is 'celery-cured' meat healthier than conventionally cured meat?

No, this is a marketing 'scam.' Whether nitrates come from a factory-produced nitrate salt or are extracted from celery, they undergo the same chemical reactions in meat to produce nitric oxide and potentially nitrosamines. The end product and its effects on cancer risk are expected to be similar, despite the 'natural' label.

What is the significance of the Wright Brothers' work in Kitty Hawk?

The Wright Brothers achieved the first successful heavier-than-air powered flight in Kitty Hawk, North Carolina. Their success was due to their rigorous scientific method, including building a wind tunnel to recalculate aerodynamic coefficients, demonstrating a pivotal moment in the history of aviation and the scientific method.

Protein Scaling, Fiber Types, Artificial Sweeteners (Ep 81)

Stronger By Science

Sports3 min read100 min video

Apr 7, 2022|9,065 views|280|35

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Key Moments

TL;DR

Protein scaling, muscle fiber types, and artificial sweetener risks are discussed in this podcast.

Key Insights

Protein requirements can likely be scaled to fat-free mass for more personalized recommendations, especially at the extremes of body composition.

Functional tests are unreliable for determining dominant muscle fiber types, and training for specific fiber types may not significantly impact hypertrophy outcomes.

Recent studies linking artificial sweeteners to increased cancer risk may be overstated due to small absolute risk differences and potential confounding factors.

Nitrates from plant-based sources are generally considered healthy, while those in processed meats warrant more caution due to potential nitrosamine formation.

The "unionization" of podcast co-hosts and profit-sharing agreements were humorously presented as behind-the-scenes podcast news.

The Outer Banks of North Carolina is highly recommended for its historical significance and the Wright Brothers Museum.

PODCAST UNIONIZATION AND ADMINISTRATIVE UPDATES

The episode opens with a humorous recounting of a "unionization" effort by podcast co-hosts during Eric's brief vacation. Greg, as spokesperson, presented Eric with a contract for more equitable footing, humorously highlighting power dynamics. This led to title changes for hosts and a 5% profit share from bulk supplement sales to the newly formed "podcast co-host union," all presented with a lighthearted, satirical tone about labor history.

FEATS OF STRENGTH AND ATHLETIC ACHIEVEMENTS

The segment highlights recent impressive feats in powerlifting. Danny Grigsby set a new all-time raw deadlift record of 1025 pounds, breaking a long-standing record with fewer "asterisks" than previous claims. Jesus Olaveras achieved a massive total in a full power meet at just 23 years old, showing significant potential. Additionally, French powerlifters Tiffany Chapan and Naomi Albear set world records in their respective weight classes, indicating a rising trend in French powerlifting.

SCALING PROTEIN RECOMMENDATIONS

The discussion delves into how protein requirements scale with body size. While some studies suggest protein needs don't drastically increase with lean body mass over short-term muscle protein synthesis, this is debated. Current research, like meta-regressions, suggests daily protein intake ranges of 1.6-2.2 g/kg for hypertrophy. Scaling to total body weight is common and simplest, but scaling to fat-free mass may be more appropriate at the extremes of body composition to avoid excessively high or low recommendations.

MUSCLE FIBER TYPE AND TRAINING OPTIMIZATION

The podcast addresses the question of whether training can be optimized by identifying dominant muscle fiber types. It's explained that muscle fiber types exist on a spectrum and can shift with training, but functional tests (like rep max percentages) are poor predictors of a person's fiber type breakdown. There's little reliable evidence suggesting that training for specific fiber types leads to significantly better hypertrophy outcomes. Both fast-twitch and slow-twitch fibers appear to respond well to various rep ranges, making direct fiber type assessment unnecessary for most individuals.

ARTIFICIAL SWEETENERS AND CANCER RISK

A recent study linking artificial sweeteners (particularly aspartame and acesulfame potassium) to increased cancer risk is discussed. However, the analysis reveals that the reported absolute risk increase is small (from ~3% to ~4%). Furthermore, the study's findings are not consistently generalizable, as artificially sweetened beverages, a major source, were not associated with cancer risk within the same cohort, while sugar-sweetened beverages and fruit juice were. The mechanism linking artificial sweeteners to cancer is also considered unclear.

HEALTH IMPACTS OF DIETARY NITRATES

The conversation clarifies the health impacts of nitrates. Plant-derived nitrates, abundant in leafy greens, are generally considered beneficial, contributing to cardiovascular health through nitric oxide production. Conversely, nitrates in processed meats are viewed with more caution due to the potential for conversion into carcinogenic N-nitrosamines. However, the presence of fiber and antioxidants in plant sources mitigates this risk. Cured meats lack these protective factors, and the high-heat cooking further increases nitrosamine formation. The distinction between "natural" celery-derived nitrates in processed meats and synthetic nitrates is highlighted as a marketing tactic with no significant health difference.

TRAVEL RECOMMENDATION: THE OUTER BANKS

Eric shares an enthusiastic travel recommendation for the Outer Banks of North Carolina. He highlights its rich history, including Roanoke Island's "Lost Colony" and the "Graveyard of the Atlantic" due to numerous shipwrecks. The area's significance in aviation history, particularly the Wright Brothers' first flight and their innovative approach to recalculating aerodynamic principles, is emphasized. The Wright Brothers Museum is highly recommended for anyone interested in science and innovation.

Mentioned in This Episode

●Software & Apps

●Companies

●Organizations

●Studies Cited

●Concepts

●People Referenced

Common Questions

Research suggests a range of 1.6 to 2.2 grams per kilogram of total body mass for optimizing hypertrophy. When scaled to fat-free mass, this is approximately 2 to 2.75 g/kg of fat-free mass. Scaling to fat-free mass is generally preferred, especially for individuals at body fat percentage extremes.

Topics

Nitrates Nitrosamines Cured Meats Nutrition Epidemiology Wright Brothers Outer Banks

Mentioned in this video

studyMorton et al. (meta-regression)

A classic meta-regression study that scaled protein recommendations to total body mass, suggesting a range of 1.6 to 2.2 g/kg for hypertrophy.

studySchwenke 2012 (high load low load study)

An outlier study that found significantly more type 2 fiber growth with heavier training compared to lighter training, a finding not replicated in other research.

locationWright Brothers National Memorial

A museum in North Carolina dedicated to the Wright Brothers and the first controlled flight, highly recommended for those interested in science and innovation.

conceptThe Lost Colony

A historical mystery on Roanoke Island, where an early English colonial settlement disappeared, mentioned as a point of interest in the Outer Banks.

organizationScreen Actors Guild (SAG)

Greg and other co-hosts joke about forming a subsidiary for fitness podcast hosts and presenting Eric with a union contract, referencing the Screen Actors Guild.

personDanny Grigsby

Powerlifter who set a new world record for the biggest raw deadlift in powerlifting history, lifting 465 kilos (1025 pounds).

studyDickerson et al. 2017

A study discussing protein recommendations for persons with obesity in a caloric deficit, scaling protein to 'ideal body weight' rather than total body weight.

studySong et al.

A study that found high nitrate intake was associated with a lower risk of gastric cancer, contradicting the idea that all nitrate sources increase cancer risk.

personRay Williams

Current world record holder in total for powerlifting, whose record Jesus Olaveira is approaching.

studyNutriNet-Santé

A population-based cohort study on artificial sweeteners and cancer risk, which found an increased cancer incidence within its cohort attributed to artificial sweeteners like aspartame and Ace-K.

drugAcesulfame Potassium (Ace-K)

An artificial sweetener linked to increased cancer incidence in the NutriNet-Santé cohort study.

personNathan Bryan

Researcher who published a review paper on inorganic nitrite and nitrate, arguing for their consideration as dietary nutrients due to cardiovascular benefits.

personJesus Olaveira

A 23-year-old powerlifter who hit a significant total of 1110 kilos, just under Ray Williams's world record, showing immense potential.

studyMcNaughton et al. 2016

A study often cited against protein scaling, examining muscle protein synthesis response to whey protein in individuals with low vs. high lean body mass. Eric critiques its limitations, such as focusing on acute MPS and having a small sample size.

locationKitty Hawk

The town in North Carolina where the Wright Brothers conducted their first successful flight experiments.

personNaomi Alabere

French powerlifter who totaled 981 pounds in the 114-pound weight class and achieved a world record squat of 363 pounds.

personBenedikt Magnússon

Previous world record holder for deadlift, whose record was broken by Danny Grigsby. His record was considered somewhat 'sketchy' due to the federation and equipment used.

personChin Wei Ling

Former world record holder for squat and total in powerlifting, whose records were broken by Tiffany Chapon.

studyMalawani et al. 2018

A study reviewed in MAS that found protein needs might be lower in women when scaled to total body mass, but identical to men when scaled to fat-free mass.

locationOuter Banks

A chain of barrier islands off the coast of North Carolina, recommended as a travel destination for its history and natural beauty.

studyBandigan et al.

A mechanistic study providing similar protein recommendations (1.7 to 2.2 g/kg) to Morton's meta-regression but focused on a shorter timescale.