In promoting long-term health, few concepts have made as profound an impact as Dr. Gabrielle Lyon’s Muscle-Centric Medicine (MCM). While resistance training is widely associated with muscular fitness, strength, and sports performance, MCM introduces a groundbreaking framework that positions skeletal muscle as the central player for strength and metabolic optimization, cellular functioning, and disease prevention. Dr. Lyon’s approach, however, extends beyond physical fitness and nutrition and instead taps into behavioral science, aligning with the Transtheoretical Model of Behavioral Change (Marshall & Biddle, 2001; Prochaska, 2020) to promote sustained lifestyle shifts. By helping to guide clients through stages of change—contemplation, preparation, action, and maintenance—MCM fosters long-term commitment to health practices that are critical for longevity. Equally important is her emphasis on feelings of worthiness, which speaks to a deeper psychological component of health where individuals begin to believe they deserve vitality and well-being, leading to lasting habit formation and healthy lifestyle changes in the process.

Moving Beyond Cardio and the Benefits of Strength Training for Muscle Growth

The existing focus on cardiorespiratory fitness in health and clinical settings has often overshadowed the importance of skeletal muscle despite substantial scientific evidence supporting its role in longevity (Braith & Stewart, 2006; Carpinelli et al., 2004; Phillips et al., 2023). In light of this, there is a need to question whether Americans are receiving the appropriate dosage of the right medicine to align with the American College of Sports Medicine’s (ACSM) assertion that “Exercise is Medicine.”

Muscle-Centric Medicine challenges conventional health approaches by prioritizing muscle for its impact on physical strength and extensive influences on metabolic function (Lyon & Baum, 2018; Sheffield-Moore & Urban, 2004), hormonal balance (Pratesi et al., 2013; Schnyder & Handschin, 2015; Volek & Forsythe, 2006), chronic disease prevention (Braith & Stewart, 2006; Hoffmann & Weigert, 2017), and cellular optimization (D’Amico et al., 2021; Zhao & Gao, 2024).

For personal trainers working with middle-aged and older populations, a Muscle-Centric approach offers significant benefits for client vitality, health span, and disease prevention. Furthermore, it provides a structured framework for high levels of client engagement, habit formation, exercise consistency, and endorsement of a healthy lifestyle.

Reframing Muscle: From Aesthetic to Endocrine Powerhouse

Traditionally, skeletal muscle has been framed in the context of strength training and physical appearance. However, Dr. Lyon’s (2023; 2022) approach invites us to rethink muscle as a dynamic endocrine organ that releases myokines—hormone-like proteins that have far-reaching effects on the body. For example, research has shown that these myokines play crucial roles in regulating glucose metabolism, insulin sensitivity, and inflammation, all of which are key to maintaining metabolic health and preventing chronic diseases like diabetes, cardiovascular disease, and obesity (Delezie & Handschin, 2018; Giudice & Taylor, 2017; Hoffmann & Weigert, 2017).

Consequently, by reframing skeletal muscle as an endocrine organ, trainers can shift the conversation with clients away from purely aesthetic goals toward a broader vision of health. By focusing on muscle as a metabolic regulator, personal trainers can help clients achieve physical strength, long-term wellness, and disease prevention.

Why Resistance Training Is the Cornerstone

For personal trainers, resistance training should be viewed as the foundation of a robust muscle-centric program. While cardio exercises certainly have their place per the ACSM’s (2021) current guidelines for exercise testing and prescription, it’s resistance training that triggers and optimizes the release of key myokines like interleukin-6 (IL-6) and irisin—both of which play vital roles in fat metabolism, glucose regulation, and inflammatory response (Febbraio & Pedersen, 2005; Hoffmann & Weigert, 2017; Pedersen et al., 1997). These hormones are essential for maintaining metabolic flexibility, which is crucial as we age and our body’s ability to regulate glucose and fat decreases (Lyon, 2023)

For instance, IL-6, secreted during muscle contraction, facilitates the breakdown of fats and enhances glucose uptake, ultimately promoting insulin sensitivity. Additionally, irisin, often called the “exercise hormone,” is associated with converting white fat into brown fat, increasing energy expenditure, and improving metabolic health (Gomarasca et al., 2020). In practice, this means that even moderate resistance training can help clients build muscle and improve their body composition by reducing harmful fat stores and enhancing overall metabolic function (Lyon, 2023).

Muscle’s Endocrine Role in Aging

Perhaps the most compelling aspect of MCM is its potential to combat age-related conditions. Sarcopenia, the gradual loss of muscle mass as we age, is associated with numerous chronic conditions, from frailty (Campbell & Leidy, 2007) to insulin resistance (Tsatsoulis & Fountoulakis, 2006) and cognitive decline (Nicola et al., 2024). By prioritizing muscle health through resistance training and adequate protein intake, trainers can play a pivotal role in helping clients mitigate the effects of aging (Baum & Wolfe, 2016).

Moreover, the endocrine functions of muscles go beyond metabolism. Myokines such as IL-15 have been proven to decrease fat mass and increase muscle hypertrophy, making them crucial in combatting age-related muscle loss (Febbraio & Pedersen, 2005; Legård & Pedersen, 2019).

Therefore, trainers can educate their clients about how maintaining muscle health through regular resistance training can significantly extend both their lifespan and their “healthspan” – the period of life spent in good health without the chronic diseases typically associated with aging. Additionally, by considering the recent research by Faigenbaum et al. (2024) and Dr. Lyon’s concept of “Muscle Span,” a more comprehensive understanding of the importance of skeletal muscle in achieving positive outcomes at any age can be achieved.

The Practical Application for Trainers: Beyond the Basics

While the science behind MCM is impressive, the real challenge for personal trainers lies in its practical application. How can we apply this clinical paradigm to real-world client programs? Here are several key strategies:

1. Shift Client Conversations Toward Longevity: Educate clients about the metabolic and endocrine benefits of muscle health. This conversation is critical, especially for middle-aged and older clients who may be focused solely on weight loss. For example, instead of focusing on pounds lost, frame the conversation around muscle gained and the long-term benefits of increased insulin sensitivity and reduced inflammation (Lyon, 2023).
2. Tailor Resistance Programs to Be Safe and Promote Myokine Release: Focus on progressive resistance training programs that target major muscle groups but focus on structural balance and “physical empathy” (Lyon & Shallow, 2024). For example, compound movements targeting lower body musculature, such as squats and deadlift variations, are traditionally seen as the most effective at providing metabolic benefits beyond muscle hypertrophy (Poliquin, 2010, 2012). However, these “low ground” free-weight activities may be too challenging for more mature individuals (Lyon & Davidson, 2024). Instead, “high ground,” machine-based exercises that provide maximal external support and neurological feedback can be an excellent alternative for older and novice trainees, ultimately leading to gradually introducing more dynamic free-weight activities (Lyon & Davidson, 2024).
3. Help Client’s Understand the Importance of Adequate Protein Intake: It is essential to help clients understand the significance of adequate protein intake and caloric balance for muscle maintenance. Dr. Lyon’s (2024) emphasizes this in her complimentary e-book The Lyon Protocol. Additionally, recent scientific evidence suggests that the traditional recommended dietary allowance (RDA) for protein intake is insufficient (Cataldo & Blair, 2015; Gwin et al., 2021; Millward, 2012; Millward & Jackson, 2004; Traylor et al., 2018). Instead, aiming for a protein intake of 1 gram per pound of ideal body weight, spread across multiple feedings of at least 30 grams of quality protein per meal, can help individuals reach the “leucine threshold” required to optimize muscle protein synthesis. Consequently, it is crucial to ensure that clients are meeting their daily protein intake to support their success (Heaney & Layman, 2008; Layman et al., 2003, 2015; Paddon-Jones & Rasmussen, 2009). Nevertheless, as a trainer, it is important to work within your scope of practice and advise clients to consult with their physician or other licensed professionals before making significant changes to their nutrition.
4. Address Gender-Specific Concerns: For female clients, particularly those in peri-menopause or menopause, resistance training becomes even more critical. Declining estrogen levels can accelerate muscle loss and contribute to increased fat storage (Sheffield-Moore & Urban, 2004). By implementing skill-appropriate resistance training programs that prioritize muscular strength, hypertrophy, and bone density, trainers can help female clients manage the hormonal changes associated with aging (Baum & Wolfe, 2016; Gomarasca et al., 2020).

Conclusion: Why Muscle-Centric Medicine Is the Future of Personal Training

Incorporating Dr. Lyon’s Muscle-Centric Medicine into your personal training practice offers more than just a new perspective on muscle health—it provides a comprehensive framework for improving metabolic function, promoting longevity, and preventing chronic diseases. By leveraging the power of muscle as an endocrine organ and focusing on resistance training and proper nutrition, personal trainers can guide their clients toward a healthier, more resilient future.

This paradigm shift represents an opportunity for certified personal trainers to stay at the cutting edge of fitness science while delivering long-term, sustainable health results. As the fitness industry continues to evolve, the muscle-centric approach provides a scientifically backed foundation for enhancing physical performance and overall well-being, ensuring that clients look strong and live strong—well into their later years.

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Authored by: Tim Hanway MS CSCS ASCC ACSM-EP, Assistant Teaching Professor of Exercise Science at Simmons University and a Peak Performance Productivity Coach who empowers his clients and students to achieve sustained high performance in all areas of their lives.