Is There a Predictive Factor for Hypertrophy?

Mechanical tension, muscle damage, and metabolic stress are often viewed as the key stimuli for muscle hypertrophy. A new study asserts that mechanical activation of fast-twitch muscle fibers is the strongest determinant of muscle hypertrophy, which suggests that mechanical tension is the most noteworthy stimulus for muscle growth. This is an intuitive idea, but Greg’s segment explains why the results of this study fail to support the conclusions that were stated in the paper (and shared widely on social media). 

After that, Eric presents a segment that’s all about food selection. As flexible dieting and “IIFYM” continue to gain popularity, it’s indisputable that dieters can succeed using a virtually limitless variety of food sources, as long as they (approximately) hit their calorie or macro targets consistently. While it’s very true that dieters enjoy a great deal of flexibility in their food choices, this doesn’t mean that food source selection is irrelevant or inconsequential. In Eric’s segment, he discusses some evidence-based guidance for making food choices to facilitate a smoother dieting experience.

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TIME STAMPS

Intro/Announcements (0:00)

Shampoo versus conditioner (2:15)

Artificial intelligence for summarizing research (6:10)

• Consensus
• Elicit

What’s the primary mechanism of muscle hypertrophy? (16:01)

Confirmation bias (20:32)

Abstract and summary of new study by Hatanaka and Ishii (22:46)

• Effect of resistance training mainly depends on mechanical activation of fast-twitch fiber

Estimating the mechanical activation of fast twitch muscle fibers (27:47)

How validation studies work (31:33)

Exploring the equations used to estimate mechanical activation of fast twitch muscle fibers (34:30)

• Proposal and validation of mathematical model for resistance training

Implications of the model used by Hatanaka and Ishii (41:18)

Comparing and contrasting with longitudinal data (48:07)

• Muscle Failure Promotes Greater Muscle Hypertrophy in Low-Load but Not in High-Load Resistance Training

Conclusions (50:28)

Flexible dieting and “IIFYM” work, but specific food selection still matters (58:25)

Regulation of food intake (1:05:24)

The satiety index (1:15:53)

• A satiety index of common foods

Effect Of Different Food Groups On Energy Intake Within And Between Individuals (1:18:43)

• Effect of different food groups on energy intake within and between individuals

Some key food characteristics to consider (1:28:10)

• Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake
• Texture-based differences in eating rate influence energy intake for minimally processed and ultra-processed meals
• Time to revisit the passive overconsumption hypothesis? Humans show sensitivity to calories in energy-rich meals

Practical applications (1:32:10)

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