Defining Fitness: Flexibility
Longevity Through Mobility: Why Flexibility Deserves a Place in Training
By Dr. Janette Watkins, Contributing Researcher
Key takeaways
Flexibility predicts survival. Lower whole-body flexibility was linked to higher all-cause mortality in both men and women.
Train it like a vital sign. Programs that include flexibility help preserve function and independence.
Mobility is multi-system. Better range of motion supports gait, balance, and the ability to get off the floor—abilities tightly tied to real-world function and survival.
CrossFit’s charter is simple: pursue broad, general physical preparedness through constantly varied, functional movements performed at high intensity. Practically, that means coaching people to move well before moving fast or heavy. Mobility—adequate, usable range of motion at the joints—underpins that entire arc. If you can’t reach, hinge, or squat through a safe range, you cap your power, leak force, and invite compensations that degrade mechanics. Emerging evidence now adds something bigger: flexibility itself relates to longevity.
The new signal: whole-body flexibility and mortality
In 2024, Araújo and colleagues published a prospective cohort of 3,139 middle-aged adults (46–65 years) who completed a standardized flexibility battery (“Flexitest”) across 20 movements. They combined scores into a “Flexindex” (0–80) and tracked deaths over ~13 years. The result? Higher flexibility was inversely associated with natural mortality in both sexes even after adjusting for age, BMI, and health status. This supports that flexibility is a meaningful fitness component with prognostic value for survival [1].
This finding complements work on the Sitting-Rising Test (SRT)—a simple floor-to-stand task that integrates flexibility, balance, and strength. New analyses confirm lower SRT scores predict higher natural and cardiovascular mortality in adults 46–75 [4]. Earlier work showed the same pattern: difficulty sitting and rising from the floor tracked with greater all-cause mortality [5]. You can see functional analogs in CrossFit every day—the Turkish get-up and the burpee. Both challenge the same suite of capacities (mobility, stability, strength, coordination) required for the SRT, with the Turkish get-up adding the demand of weighted load and the burpee emphasizing speed, control, and repeatability. Together, these insights highlight what CrossFitters have always known to be true: when you lose functional movement, you lose quality of life.
Flexibility inside the healthy-aging package
Longevity is multifactorial, but cardiorespiratory fitness still wears the crown. Training the “big three”—aerobic, strength, and flexibility—appears to be additive for survival [2]. A 2023 population study found that adults who routinely engaged in all three types of activity had lower mortality risk than those who did not [2]—the same trifecta that CrossFitters practice every day just by showing up at an affiliate.
Flexibility, often overlooked, plays a direct role in function—the foundation of independence and survival. A 2022 review of supervised flexibility programs in older adults reported meaningful improvements in posterior chain mobility and practical range of motion, supporting prescriptions tailored to baseline limitations [6]. Flexibility-oriented mind–body practices also contribute: large reviews identify tai chi, which blends mobility, balance, and control, as highly effective for reducing falls in older adults—a leading cause of injury-related mortality [7]. Longitudinal evidence further shows that adding stretching or calisthenics reduces the risk of developing functional limitations, helping people maintain the everyday abilities that sustain independent living [3].
Why mobility maps to mortality
Flexibility maps so closely to longevity for two main reasons that every coach instinctively recognizes. First, real-world movement is a systems integration challenge: joints, tendons, neuromuscular control, and cardiorespiratory support must all work in unison. When mobility is restricted, compensations emerge—leaking force, stressing tissues, and elevating injury risk. In contrast, greater mobility enables efficient mechanics, full range of motion under load, and safer, more sustainable motor patterns.
Second, independence hinges on mobility. The capacity to get off the floor, reach, and turn safely in daily life is mobility-dependent. The predictive power of the Sitting-Rising Test (SRT) reflects this reality: the inability to sit and rise without compensation signals deficits in balance, strength, and musculoskeletal resilience—factors that track tightly with morbidity and mortality [4,5].
What this means for CrossFit clinicians and coaches
CrossFit already bakes in mobility—full-ROM squats, overhead work, front-rack positions, deep lunges, and daily PVC/foam-roller prep. The point isn’t to swap intensity for stretching; it’s to recognize mobility as a trainable capacity. When you treat it that way, two things happen: (1) you unlock safer, more efficient intensity, and (2) you target outcomes that matter on their own—function and survival.
The most effective approach is to dose mobility “little and often.” Just 5–10 minutes in warm-ups or cool-downs, paired with 10–15 minutes at home, can make a difference. Focus on the sticky joints—ankle dorsiflexion, hip rotation, and thoracic extension—and on the positions that buy the most function: deep squat, front-rack, overhead, hinge, and rotational reach. Use a mix of methods to build adaptability: dynamic drills before training, static holds after, contract–relax (PNF) two to three times weekly, and loaded end-range work for tissue resilience. Evidence confirms that supervised flexibility programs improve mobility in older adults [6], and that pairing balance with mobility both reduces fall risk and expands usable range of motion [7].
The bottom line
Flexibility isn’t fluff—it’s a lever for longevity. Large cohort studies link limited mobility with higher mortality, while mobility-integrated programs help preserve function and independence. Train athletes to own big ranges first, then layer on speed and load. The payoff isn’t only better performance—it’s the foundation for staying capable, independent, and alive longer.
Action Steps for Coaches
Flexibility “vitals.” Track key joints—ankles, hips, shoulders, and thoracic spine—to spot restrictions.
Field tests tied to outcomes. The Sitting-Rising Test (SRT) or the max-weight Turkish Get-Up are quick to administer, sensitive to progress, and strongly tied to independence and mortality outcomes.
Make it measurable. Record ROM in centimeters or degrees, log flexibility scores, and note movement quality alongside loads and times to show progress. Even simple markers—like tracking squat depth by box height (e.g., progressing from 20" to 16")—give both coach and athlete a clear, measurable goal.
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