The Complete Exercise Guide Muscle Hypertrophy

By Holly T Baxter

"Save time. Consolidate your knowledge. Achieve your goals faster… by working out the correct way!

If you are anything like me, you'll likely agree that one of the most frustrating things when it comes to achieving your health & fitness goals is the challenge of finding quality evidence based information.


Who do you entrust your health & fitness to? Especially with so many "Influencers" each claiming to be experts?



In my early career, I realized just how difficult this process could be, and have since spent the next decade surrounding myself with highly regarded, well respected academic researchers to help sharpen this skill.


My new book 'The Complete Exercise Guide To Muscle Hypertrophy', with scientific research serving as the backbone, will teach you about the myriad of resistance training concepts and training techniques, such as

How Do Muscles Grow?

Average Rates of Muscle Hypertrophy

Exercise Volume

Rest Periods

Low Load Training

Periodization

Hormones

Muscle Memory

Sex Differences

Blood Flow Restriction


And… will explain the role each of these concepts play in optimizing muscle growth…. plus so much more!


All thirteen chapters of this book have been written in an easily digestible format, and offer many different scientific perspectives (some of which have not yet made their way to social media circles!)..... As well as the perspectives I hold as a coach and as a professional physique athlete on each of these described topics.

• Language: English
• Publisher: BookBaby
• Release date: Jan 8, 2024
• ISBN: 9798350930382

Book preview

00

Preface

The following book communicates the current understanding of skeletal muscle growth and the adaptation that takes place in response to various forms of exercise. The intention of this book is to communicate the experimental evidence that guides our current understanding of muscle growth, and to deliver easy to understand descriptions and summaries of key research that have collectively shaped our way of thinking.

One of the most frustrating things for me early in my career was the challenge of finding good evidence and attempting to synthesize and understand what was being communicated in various scientific papers. I quickly realized how difficult this process could be, and have thus spent many years surrounding myself with the proper mentorship to help sharpen this skill.

As I became more acquainted with the scientific literature, I also realized that science is often just as divided, as is the fitness industry itself! I naively assumed that the many tenets I had learned about during my schooling were well established concepts and largely agreed upon by the experts in a given area. One would assume that a well written scientific paper from a respected research group would be above reproach. However, over the years I have learned that there is a great deal of conflicting evidence when it comes to several aspects of resistance training that are commonly touted amongst fitness influencers.

For me, observing this clear division of consensus was an exciting opportunity to learn, which has helped me to develop nuance in my understanding of various training principles, as opposed to relying on a single study or an expert, and you can insert just about any popular fitness influencer here, to reach a conclusion.

When reading this book, research will serve as the backbone to help you understand various concepts. Admittedly, many individuals find research boring, tedious, and out of touch with what practitioners actually employ with their clients. However, I’ve tried my very best to break down the research in an easy and digestible manner, while including different scientific perspectives, as well as the perspectives I hold as a coach, on each of these topics.

For example, I won’t tell you that a research study suggests that there is a dose-response relationship between training volume and muscle growth (more volume = more growth). Instead, I will discuss how much growth was observed in that study, how it compares to other studies and present you with evidence which might also disagree with this idea.

Finally, I will provide a summary from a researcher and a coach’s perspective. I believe that this will provide you with a more balanced discussion on each of the topics I have covered, which will help you develop your thinking around that subject. Far too often, online evidence based communicators present a one sided view on a given topic, or their expert opinion. This often results in a single popular narrative gaining traction without the proper nuance it deserves. Exercise volume, rest periods, exercise tempo, periodization…all of these topics have evidence for and against various training manipulations (many of which you’ll probably have heard of). This book will break down all of these concepts in an open and transparent, easy to digest manner.

Moreover, my hope is that this book will provide you with the information to critically think about various training principles. If you subscribe to taking shorter rest periods in your hypertrophy training program, this book will help you understand why that approach may be beneficial, at times. If you are an advocate for lower training volumes, the information I discuss may help to develop your thinking in deciding how much volume is actually necessary. If you are working with a client who is brand new to resistance training, this book will help you to understand how much muscle growth is observed with resistance based training over a given period of time, in order to develop more realistic client expectations and training outcomes.

Finally, I want to thank you all, from the bottom of my heart for purchasing this book, and hope that it provides you with the utmost of value, not only for your own training goals and fitness endeavors, but to those of your clients, if you are purchasing this book for the purpose of building a successful, evidence based coaching business.

01

Muscle Growth: an Overview

Skeletal muscle tissue is a highly plastic tissue that many seek to alter through various types of exercise [1]. Most commonly, individuals will engage in resistance exercise with the hopes of increasing both their muscle size and strength. When you lift a weight, it acts as a mechanical stimulus on the muscle tissue. This means that your muscle is contracting in efforts to overcome and move this mechanical load. The presence of a mechanical stimulus is thought to be one of the most important factors for stimulating muscle growth. It is also thought that metabolic factors and muscle damage may contribute to muscle growth (which is discussed later in this chapter). Through a complex process, the mechanical signal is converted into a molecular reaction that results in the signaling of muscle protein synthesis. As its name implies, muscle protein synthesis is the synthesis (or formation) of new proteins. Of course, skeletal muscle tissue is made up of many different proteins. The proteins that many people are familiar with are actin and myosin. These are also known as the thick filament (myosin) and the thin filament (actin). Actin and myosin are the primary contractile proteins that are found at the most intricate level of skeletal muscle (the sarcomere). However, before we get to the intricacies of a sarcomere, it is important to first understand the organization and hierarchy of skeletal muscle.

Muscle Deconstructed

When you deconstruct a muscle, you first find that the whole muscle is surrounded by a layer of connective tissue known as the epimysium. This sheath of connective tissue merges at the ends of the muscle with the connective tissue of the tendons [2]. The tendon attaches to the bone, thus the epimysium ultimately allows force generated by the skeletal muscle to transmit to the connective tissue of tendons, which help to move your bones. Looking deeper into the muscle, the next level of organization are bundles of muscle fibers which are known as fascicles (Figure 1.1). These fascicles are also surrounded by a layer of connective tissue known as the perimysium[3]. A muscle fascicle may contain anywhere from dozens to hundreds of muscle fibers [2]. These fibers themselves are surrounded by a layer of connective tissue known as the endomysium. Thus, force is generated by muscle fibers and that force is transmitted through the connective tissue (i.e. Endomysium, Perimysium, Epimysium), to eventually reach the connective tissue of the tendon causing movement.

Muscle fibers are an important component of skeletal muscle. An individual muscle fiber will vary in diameter anywhere from 10-100 microns (There are 10,000 microns in a centimeter) and will vary in length, anywhere from 1 mm to the full length of a muscle [2]. A muscle fiber is considered an individual muscle cell [2]; however, there are further levels of organization, which can help to better understand how muscles generate force. Specifically, muscle fibers are made up of myofibrils (Figure 1.1). Myofibrils are made up of sarcomeres (Figure 1.2), which is considered the smallest functional unit within skeletal muscle. A sarcomere is made up of protein filaments (primarily actin and myosin) that interact with each other to produce force. The current theory to help understand force generation at the sarcomere is known as the sliding filament theory [4]. According to the sliding filament theory, force is generated when myosin (the thick filament in a sarcomere) pulls actin towards the center of the sarcomere. As illustrated in Figure 1.2, the myosin filament contains a bulb or head like structure which acts as an engine. The myosin heads latches onto the actin protein and pulls it inward, shortening the sarcomere. The process of a sarcomere shortening is illustrated in Figure 1.3. Other notable structures of the sarcomere are the z lines, which allow the transmission of tension from one sarcomere to the next, and titin, which works as a molecular spring to provide additional force while a muscle is lengthening (Figure 1.2).

Figure 1.1

Figure 1.1 displays the organizational structure of skeletal muscle.

Figure 1.2

Figure 1.2 depicts a sarcomere. A sarcomere is made up of the thick filament (myosin) and the thin filament (actin).

Figure 1.3

Figure 1.3 displays the sarcomere at different lengths: A) depicts a shortened sarcomere, where there is greater overlap between actin and myosin; B) Depicts a sarcomere at a moderate length, where there is moderate overlap between actin and myosin; C) Depicts a lengthened sarcomere where there is less overlap between actin and myosin.

Muscle Growth

Now that we have detailed the structure of skeletal muscle, it is easier to understand the process of muscle growth. When your muscles have grown, you know this because your muscle appears larger. This increase in muscle size reflects the addition of sarcomeres within a myofibril (Figure 1.4), which results in larger muscle fibers. The increase in the size of the muscle fibers causes an increase in fascicle size, which is ultimately reflected at the whole muscle level. Exercise induced muscle growth is typically described as an increase in length of a muscle or an increase in the cross-sectional area of a muscle [5]. However, most models of muscle growth suggest that the majority of muscle growth is driven by an increase in muscle cross-sectional area (known as radial growth) [5]. This type of growth is often referred to as myofibrillar growth as the increased muscle size ultimately reflects an increase in proteins associated with the myofibril (i.e., actin and myosin). So, we can consider muscle growth as the addition of sarcomeres to a myofibril (illustrated in Figure 1.4). However, the fibers themselves are suspended in an aqueous media known as the sarcoplasm [6]. Proportionally, skeletal muscle is 75% water, 10-15% myofibrillar protein and around 5% non-myofibrillar protein (aka sarcoplasmic protein)[6]. The sarcoplasmic component is said to include the sarcoplasm (the aqueous medium the myofibrillar and non-myofibrillar components reside [6]) along with the other non-myofibrillar components of a muscle cell [6].

Figure 1.4

Figure 1.4 is adopted from Jorgenson et al. [5] and displays different proposed models of the addition of new filaments to existing myofibrils. The following models are depicted: A) displays the addition of new filaments to the periphery of a myofibril; B) displays the addition of new filaments to the center of a myofibril; C) displays the addition of new filaments spread evenly throughout a myofibril

Sarcoplasmic Muscle Growth

Although the general scientific consensus is that skeletal muscle growth is represented by a proportional increase in myofibrillar protein and sarcoplasmic space, there has been recent discussion around that idea that higher volume training may produce a disproportionate increases in sarcoplasmic space/proteins [6]. Since myofibrillar proteins produce force, and the sarcoplasmic space provides support for the force producing elements, a disproportional increase in the sarcoplasm may be expected to result in an increase in muscle size without a proportional increase in muscle strength. This is a tempting hypothesis, as bodybuilders will often train with high volumes that produce large increases in muscle size, which may not be accompanied with proportional increases in strength. This begs the question, are bodybuilders increasing the non-contractile component of their muscle? Are their muscles just for show? Do those who train specifically for strength build muscle tissue that is of a greater functionality (i.e., myofibrillar instead of sarcoplasmic growth)? Is it necessary to lift heavy weight to grow both the myofibrillar and sarcoplasmic components of your skeletal muscle? These are all interesting questions, which I hope to provide further insight on later in this book.

Much of the discussion around sarcoplasmic hypertrophy comes from a 2019 study by Haun et al. [7]. Authors employed a 6 week high volume training study, where individuals worked up to 32 sets of 10 repetitions of Barbell (BB) back, squats, 32 sets of 10 repetitions of BB bench press and overhead press combined, 32 sets of 10 repetitions of BB stiff-legged dead-lift, and 32 sets of 10 repetitions of lat pulldowns. The complete program is provided in Table 1.1. By most individuals’ standards, this would be considered an extremely high volume of exercise. Authors examined changes in myofibrillar protein (actin and myosin), sarcoplasmic protein, mitochondrial content, and glycogen concentrations following 6 weeks of this program. Ultimately the authors found that the muscle fiber cross-sectional area had increased by 23%. When they looked at the make-up of the fiber, they speculated that actin and myosin proteins had decreased (~30%) in proportion to other components in the muscle. In addition, authors found that several proteins associated with the sarcoplasm were upregulated.

Table 1.1 Training Program from Haun et al. [7]

This led to the interesting suggestion that increases in muscle fiber size, in response to high volume training, is largely attributed to a sarcoplasmic hypertrophy (at least in the short term). Although this data is really intriguing, the larger scientific community has not conclusively agreed that disproportional sarcoplasmic hypertrophy plays a large role in muscle growth resulting from high volume training.

Despite increasing discussion around the possibility of disproportional sarcoplasmic hypertrophy, the scientific community is far from closing the book and concluding that (for