Debunking 4 Common Bodybuilding Myths: Evidence-Based Insights

Myth #1: Direct Exercises Stimulate More Muscle Growth Than Indirect Exercises

This myth has gained popularity recently, but it's not only false - it's nonsensical. Some people attempt to categorize exercises as "direct" or "indirect," but this classification doesn't hold up under scrutiny.

When you contract your biceps during a curl, it's the same type of contraction as when you perform a row. There's nothing indirect about the biceps contraction during a row - there's a demand for elbow flexion, so the elbow flexors contract. It's that simple.

Some individuals use the term "direct" to refer to isolation or single-joint exercises, and "indirect" for compound or multi-joint exercises. However, this distinction is still inaccurate.

Research Findings

A 2023 meta-analysis examined studies comparing single-joint exercises to multi-joint exercises (roughly corresponding to isolation vs. compound exercises). The conclusion? There's no difference in muscle growth between these exercise categories in general.

You might feel a muscle more intensely or focus on it better during an isolation exercise, but that doesn't make it more effective. The research is clear on this point.

The Hip Thrust Example

The hip thrust is an excellent example of how this myth falls apart. Many people consider it an isolation exercise, but it's actually a multi-joint movement. Studies have shown significant quadriceps growth from hip thrusts, as the quads are heavily recruited during the exercise.

Researchers have also examined what happens when you adjust foot placement during hip thrusts:

• Moving feet further away increases hamstring activation
• Tucking feet closer increases quad activation
• Glute activation remains consistent regardless of foot placement

This demonstrates that the body isn't so inefficient that contracting one muscle group prevents another from reaching its full potential. Whether you contract other muscles simultaneously or not doesn't affect how a specific muscle contracts.

Not All Exercises Are Equal

While the direct vs. indirect classification is flawed, it's true that not all exercises are equally effective for every muscle group. This is where the concept of "fractional volumes" comes into play.

Fractional Volume Counting

A more accurate approach is to count exercises as fractional volumes towards different muscle groups. For example:

• Count dumbbell rows as 50% volume towards biceps
• Fully count exercises that allow maximal contraction for a muscle group
• Partially count exercises that involve a muscle group but don't allow full contraction or maximal force output

A 2024 meta-analysis confirms that counting volume fractionally is more effective. The relationship between volume and muscle growth was significantly stronger when using fractional volumes compared to counting only "direct" volume or treating all exercises equally.

For meticulous program design, consider assigning fractional volume contributions to exercises based on their degree of involvement for each muscle group.

Myth #2: Free Weights Are More Effective for Muscle Growth Than Machines (Or Vice Versa)

This myth exists in both directions, with some claiming free weights are superior and others arguing for machines. The reality? It doesn't make a significant difference.

Muscle Contraction Is Key

Your muscles don't care about the source of resistance. They only respond to the degree of contraction, which determines the mechanical tension that stimulates anabolic signaling cascades. This mechanical tension ultimately drives muscle growth.

The degree of contraction and force output required during a particular movement is what matters - not whether that movement is performed using a machine, dumbbells, barbells, kettlebells, or any other implement.

Research Supports Equality

Multiple studies have compared machine and free weight exercises that are otherwise similar, and the results are clear:

A 2021 meta-analysis concluded that free weights and machines are, on average, equally effective for muscle growth.

The Pulldown Machine Example

The pulldown machine serves as an excellent illustration of both this myth and the previous one:

1. Despite being a machine exercise, it's highly effective for muscle growth
2. Although it's a compound, multi-joint exercise, it's still very effective for biceps development

This example demonstrates that neither the equipment type (machine vs. free weight) nor the exercise classification (compound vs. isolation) determines effectiveness.

Fixed vs. Free Motion

Some argue that machines with a fixed range of motion are inferior to free weights or cable machines. However, research has examined fixed-motion machines as well:

Studies conclude there is no difference in muscle growth between fixed movement patterns and free movement patterns, provided the exercises involve the same musculature to a similar degree.

Myth #3: CNS Fatigue Is a Serious Problem Causing Prolonged, Central Fatigue

The concept of "CNS fatigue" as commonly discussed in fitness circles is largely a myth. When you hear the term "CNS fatigue," it's often more accurate to replace it with "mental fatigue," "exhaustion," or simply "I feel tired."

The Facts About Fatigue

1. Central fatigue is exceptionally rare
2. Muscle fatigue is a local process
3. Muscle growth is locally regulated
4. There is almost no systemic contribution to fatigue from strength training

Research Findings

Multiple studies have examined this topic:

• One study concluded: "The force behavior commonly attributed to central fatigue could be explained solely by peripheral factors and questions the very need for the existence of central fatigue."

• A systematic review and meta-analysis of 52 studies found: "Overall, the findings do not support the existence of a general non-local muscle fatigue effect. However, when examining specific types of performance outcomes, there may be an effect specifically upon endurance-based outcomes."

High-Intensity vs. Low-Intensity Training

Contrary to popular belief, high-intensity lifting causes less fatigue than low-intensity lifting:

• After a 3-rep max, you can't lift your 3-rep max again
• After a 20-rep max, you're too fatigued to lift your 20-rep max or your 3-rep max

This corresponds with the total work done - you perform much more work in a high-rep set, leading to greater fatigue.

Deadlifts and Other Compound Lifts

Research has specifically examined powerlifts like deadlifts and found they don't significantly differ from other exercises in terms of neuromuscular fatigue generation.

What makes these lifts feel more fatiguing?

• They demand precise technique
• People often invest more personal pride and effort
• They require greater mental concentration
• They involve a large portion of the body

All of these factors contribute to mental exhaustion, not CNS fatigue.

The Truth About CNS Fatigue

There is a component of what's called "CNS fatigue," but ironically, it's almost entirely local:

• It affects muscle groups innervated by specific motor neurons
• Often, it doesn't even affect entire muscle groups, just specific muscle fibers
• The fatigue is extremely localized

Why Is It Called CNS Fatigue?

The term "Central Nervous System fatigue" is somewhat misleading:

• The body of the motor neuron lies in the central nervous system (spinal cord)
• Technically, it's part of the CNS
• However, the axon extends outward to innervate muscle fibers
• The fatigue effect occurs at the neuromuscular junction and in the muscle fibers

So, most "CNS fatigue" is actually local fatigue, not true central fatigue.

Mental Fatigue vs. CNS Fatigue

What people often describe as CNS fatigue is usually mental fatigue:

• You can become tired from any effortful activity
• Activities you dislike can cause mental fatigue (e.g., long family events, commuting)
• This is more related to motivation and willpower than neuromuscular effects

For most people, when performance is measured objectively, it doesn't decrease significantly. The rate of perceived exertion may increase, but actual performance often remains consistent.

Myth #4: You Can Take Volume from One Muscle Group and Add It to Another

This myth often manifests as the idea that you can reduce lower body volume to increase upper body volume. While it's true that adding volume to a muscle group can increase gains (if you're not at your maximum adaptable volume), the concept of "transferring" volume doesn't make sense physiologically.

Local Regulation of Muscle Growth and Fatigue

Muscle growth and fatigue are predominantly local processes:

• They are locally regulated
• Stimulated by local mechanical tension on specific muscle fibers
• Both fatigue and growth are regulated by the contraction of specific muscles

Your upper body can't handle more volume simply because you've reduced lower body volume.

The Hormone Hypothesis

Some studies have suggested that training the lower body might improve upper body gains, potentially through hormonal mechanisms. However:

• Higher quality research typically finds no effect
• The proposed mechanisms don't align well with our understanding of locally regulated muscle growth

If anything, research slightly favors the idea that more lower body volume might improve upper body gains, not the other way around.

When Volume Redistribution Makes Sense

The only scenario where redistributing volume might be beneficial is if you're limited by time or mental resources:

• If you don't have enough time or willpower to train everything optimally
• You need to prioritize certain muscle groups
• The muscle group receiving more volume isn't at its maximum adaptable volume yet

Independent Growth Potential

In principle, each muscle group has its own capacity for growth based on the volume allocated to it:

• Muscle A grows X amount with Y volume
• Muscle B grows Z amount with W volume
• The volume allocated to Muscle A doesn't affect Muscle B's growth potential

There's no interaction effect between volume allocation for different muscle groups. The volume for a specific muscle group determines the gains for that muscle group alone.

Conclusion

Understanding these myths and the science behind them can help you optimize your training approach:

1. Don't worry about "direct" vs. "indirect" exercises - focus on overall muscle activation and progressive overload
2. Choose exercises based on personal preference and biomechanics, not whether they're machine or free weight
3. Manage your mental fatigue and recovery, but don't stress about mythical CNS fatigue
4. Allocate volume to muscle groups based on your goals and recovery capacity, not by "transferring" from other areas

By basing your training on evidence rather than myths, you'll be better equipped to make progress and achieve your muscle-building goals efficiently and effectively.

Practical Applications

To apply these insights to your training:

1. Use a variety of exercises for each muscle group, including both compound and isolation movements
2. Experiment with both machines and free weights to find what works best for you
3. Focus on progressive overload and proper form rather than arbitrary exercise classifications
4. Monitor your overall fatigue levels, but don't attribute all tiredness to "CNS fatigue"
5. Design your training split based on your recovery capacity and goals, not myths about volume redistribution

Remember, individual responses can vary. While these principles are based on scientific evidence, it's always important to pay attention to your body's signals and adjust your training accordingly.

Further Learning

To deepen your understanding of evidence-based training principles:

1. Stay updated on the latest exercise science research
2. Critically evaluate claims made in fitness media
3. Consult with qualified professionals who base their methods on scientific evidence
4. Experiment with different approaches while objectively tracking your progress

By combining scientific knowledge with practical experience, you'll be well-equipped to optimize your training and achieve your fitness goals.

Article created from: https://www.youtube.com/watch?v=gPN2NikDCA4