Muscle Span: The Longevity Metric You’ve Never Head Of | Dr. Matt Jordan

What is muscle span — and why does it matter?

[0:00]

Dr. Jordan opens the conversation by reframing a concept that most people associate exclusively with athletic performance. The term span exists in the health world in two well-established forms — lifespan and healthspan — but muscle, he argues, deserves its own span. Muscle span is about maintaining the functional capacity of your muscular system across your entire lifetime so that you can continue to do the things that define independent living: climbing stairs, rising from a chair, walking fast enough to cross a road, playing with grandchildren.

The standard perception of muscle-building — gym bros, tank tops, chasing aesthetics — is a cultural distortion that has kept most people from accessing its most important benefits. Dr. Jordan’s thesis is simple: the weight room matters more for the 65-year-old woman who wants to stay in her house than it does for the 22-year-old looking to get jacked. When you reframe muscle as infrastructure for your independence, the entire calculus changes.

“Muscle span might be this concept that illuminates, for somebody aiming to improve their longevity, this other aspect that we don’t actually think about a lot.”
— Dr. Matt Jordan

The social barriers blocking access to resistance training

[7:59]

Building muscle has a participation problem. Research Dr. Jordan assigns to his graduate students describes a “glass ceiling” on muscular strength for women — invisible social headwinds that cause women to self-select out of environments where they could build the very reserve they need most. These headwinds include messaging that equates muscularity with masculinity and gym culture that communicates, implicitly and explicitly, “this is not for you.”

The same dynamic plays out for older adults, for people with larger body frames (who are, counterintuitively, often well-positioned to excel at strength training), and for anyone whose only exposure to the gym has been the intimidating aesthetic of peak-performance culture. The solution is not just information — it is reframing who the weight room is actually for.

Muscle health across the lifespan: a stage-by-stage breakdown

[11:41]

Dr. Jordan systematically walks through every phase of life, making clear that no age group gets a pass on muscle health. A few highlights:

• Children: Muscular strength has measurably declined in children compared to 40 years ago. The culprit is multifactorial: more screen time, less free outdoor play, and early sports specialization that prioritizes one movement pattern at the expense of general physical development.
• Adolescents (female): ACL rupture rates for teenage female athletes are dramatically higher than their male counterparts. Muscular strength is a primary modifiable factor in reducing that risk.
• 20s–40s: Muscle qualities begin declining from as early as age 30 in physically inactive individuals, at roughly one percent per year. The decline accelerates through middle adulthood.
• Perimenopause: Women entering this phase face an acute, simultaneous loss of bone density and muscle mass. Resistance training is the most effective known intervention.
• 60s–90s+: Studies involving adults in their mid-90s demonstrate that meaningful improvements in muscle mass, strength, power, and functional capacity are still achievable through progressive resistance training combined with nutritional support.

“Is there ever a point where you’re over the hill? No. When is the best time to start? Now.”
— Dr. Matt Jordan

Dr. Jordan’s mother: a story about what’s actually possible

[26:18]

One of the most memorable segments of the episode is a personal story. Dr. Jordan describes his mother, a career computer programmer who reached her early 70s with type 2 diabetes, high blood pressure, high cholesterol, and osteoporosis. During Covid, she reflected on what she wanted the next phase of her life to look like — not a short-term body composition goal, but the ability to stay in her home and maintain her independence. That vision led her to book an appointment with a personal trainer, cancel it five times, and then go.

Within two years she was deadlifting 100 pounds. Her type 2 diabetes had reversed. She was off blood pressure medication. Her lipids had normalized. She had a new social circle built around her gym community. The example is not extraordinary for what it says about one individual — it is extraordinary for what it says about what is available to almost anyone, at almost any age, who decides to start.

Strength versus power: understanding the distinction that matters most

[33:27]

Dr. Jordan introduces a distinction that is central to his research and that most people have never considered. Strength — the maximum force your muscles can produce — functions like a bank account. It is the reserve you accumulate. Power — force produced rapidly — functions like your monthly income: the active, moment-to-moment currency of functional life.

Muscle power is the single biggest predictor of whether you can live independently across the age span. It peaks in your 20s and, in physically inactive individuals, declines by one to two percent per year from your 30s and 40s onward. By the time someone is in their 80s and 90s, power output may have dropped from approximately 49 watts per kilogram (average for a healthy adult) to around 10 watts per kilogram — a level insufficient to meet the basic demands of daily living. When power drops below roughly 7 to 8 watts per kilogram, the ability to get out of a chair unassisted, to manage stairs, and to live at home is typically gone.

For reference, Dr. Jordan notes that elite athletes can reach 65–70 watts per kilogram. A USA bobsledder tested in his lab once hit 85 watts per kilogram — equivalent to the power output of a bonobo chimpanzee. The gap between elite human performance and the threshold for functional independence is both sobering and motivating.

Mechanical biomarkers: what your blood panel cannot tell you

[44:40]

The conversation introduces a framework that Dr. Jordan believes should sit alongside standard medical diagnostics. Blood biomarkers — lipid profiles, blood glucose, hormone levels — tell you a great deal about lifespan risk. What they do not tell you is how your body is functioning right now, and how it will function in 20 years.

Mechanical biomarkers fill that gap. They include:

• VO2 max — aerobic capacity, a well-established predictor of mortality
• Muscle strength — the reserve capacity of your muscular system
• Muscle power — the functional output that determines daily independence
• Rapid force capacity — the ability to generate force in under 100 milliseconds, critical for fall prevention and injury resilience
• Balance and gait patterns — movement signatures that change measurably with aging, injury, and the earliest stages of neurological decline

These metrics, Dr. Jordan argues, are what determine whether your healthspan matches your lifespan. You cannot get this picture from a blood draw.

A tour of the lab: the machines and what they measure

[34:29]

Dr. Jordan walks through the core equipment in his University of Calgary lab in terms accessible to any listener. Three instruments are explained in detail:

Force plates. Grounded in Newton’s laws of motion, force plates measure the forces your muscles generate as you push against the ground. Dr. Jordan’s interest in force plates came from a 2008 presentation on their use with adults in their 80s — which he then brought back to Olympic athletes, reversing the typical direction of research translation. Force plates are used to measure jump power, landing mechanics, and asymmetries between limbs — all proxies for the health of the neuromuscular system.

The robotic leg press. Unlike conventional free weights, this machine can measure both the gas-pedal (concentric) and braking (eccentric) actions of muscle independently. It allows for safe, auto-regulated strength assessment and training in clinical and rehabilitation contexts, and gives Dr. Jordan a precise read on maximal leg strength — the size of the muscular bank account.

The rapid force dynamometer. A custom-built device designed to measure how much force you can produce in approximately 100 milliseconds — the interval that governs slip-and-fall recovery, ACL rupture events, and reactive balance. An ACL can rupture in as little as 50 milliseconds. Rapid force capacity declines differently than peak strength, and its decline is strongly associated with aging. This metric is distinct from how big your bank account is; it measures how fast you can access it.

Plantigrade: turning your gait into a vital sign

[1:03:35]

The episode closes with a segment on Plantigrade — a smart insole technology co-developed by Dr. Jordan. The origin story is personal: the company’s CEO, Quinn Sandler, approached Dr. Jordan after his father was diagnosed with prostate cancer. Together, they set out to build a wearable that could capture the mechanical biomarkers that no existing consumer device was measuring: step-by-step force, stride symmetry, walking speed, and gait pattern variability.

Now roughly eight to nine years into development, Plantigrade is a validated, clinical-grade system used by elite sports organizations, rehabilitation clinics, and research institutions. The technology automatically detects walking, running, jumping, and directional change, and delivers biomechanical data that is highly sensitive to the kinds of changes that precede serious health events.

“Your walking patterns are the first things to change with cognitive decline, with Parkinson’s disease, with Alzheimer’s. You see clear signal early that things are shifting in your baseline patterns of movement.”
— Dr. Matt Jordan

Dr. Jordan illustrates the clinical value with the story of Gabe Landeskog, captain of the Colorado Avalanche, who sustained a severe knee injury and spent over 1,000 days working to return to the ice. Every morning, the care team reviewed Landeskog’s walk patterns — collected via Plantigrade — to make real-time training decisions: green light, yellow light, or red light for the day. Landeskog’s return, documented in the HBO Max documentary A Clean Sheet, is presented as both a case study in the technology’s utility and a testament to what a patient, data-informed recovery process can produce.