Defining Fitness: Power
Why Power Matters: Training Speed for Longevity
Written by Dr. Janette Watkins with contributions from Jennifer Pishko, MS.
Key Takeaways
Power = health currency. Muscle power outpredicts strength for mortality.
Train fast. Apply fast intent to functional movements at appropriate loads with full recovery. Expect improvements in mobility, balance, and ADLs—the mediators linking power to independence and survival.
Measure average power. Use simple metrics to track and reward doing more work in less time—a cornerstone of CrossFit’s measurable, observable, repeatable model.
CrossFit’s methodology has long centered on producing higher average power outputs across functional movements, scaled appropriately to the athlete’s ability [1]. The research findings provide scientific reinforcement for what has been observed in practice: improving how fast people can move meaningful loads—rather than focusing solely on how heavy those loads are—has profound implications not just for performance, but for day-to-day function and long-term health [1,2].
The new flagship study: power predicts survival better than strength
CrossFit defines intensity as power—“the time rate of doing work,” or simply force × distance ÷ time [1]. This physics-based lens is not just semantics; it’s the backbone of why CrossFit works: higher average power output is the independent variable most closely linked to favorable fitness adaptations. Over the past two decades, research has increasingly shown that muscle power—the ability to produce force quickly—declines faster with age, closely tracks with real-world function, and, crucially, predicts survival.
A landmark prospective cohort study published in Mayo Clinic Proceedings (2025), tracked 3,889 adults aged 46 to 75 over a median follow-up of 10.8 years [2]. Their goal was to directly compare two closely related but distinct measures of muscular capacity—relative muscle power and relative strength—to see which better predicted longevity. The findings were striking: muscle power emerged as the stronger predictor of all-cause mortality, while strength lost statistical significance once other factors were accounted for. In practical terms, this means that how quickly an individual can produce force relative to their body size may matter more for survival than the maximum amount of force they can generate. The authors conclude that assessing and training muscle power should be a clinical priority for promoting healthy aging and extending lifespan [2].
Evidence consistently shows that power often outperforms strength when it comes to functional outcomes. A meta-analysis of 13 randomized trials found that power training—moving lighter loads at higher speeds—improved physical function more than traditional strength training in older adults, with notable gains in timed chair-stands, gait speed, and other proxies for activities of daily living [3]. This advantage translates beyond controlled settings; the Powerful Ageing trial (2025) demonstrated that a pragmatic, power-focused program delivered in community environments significantly increased both muscle power and overall physical functioning in older adults, underscoring the scalability of coached, real-world implementation [4]. The mortality signal tied to power is not new either. In the Baltimore Longitudinal Study of Aging, arm-crank power was a stronger predictor of all-cause mortality in men than isometric strength [5]. Even simple field tests with a power component, such as sit-to-stand metrics, closely tracked with gait speed and mobility in aging populations, and chair-stand performance shows a graded relationship with mortality in clinical cohorts [6,7].
Power in younger populations: building a foundation early
While most longevity research focuses on older adults, evidence also supports the importance of developing power in youth. In adolescents, higher muscle power is associated with faster sprint times, greater jump height, and improved change-of-direction ability—key attributes for both sport performance and functional competence [9]. Plyometric and Olympic lifting–based programs in teenage athletes have been shown to significantly improve neuromuscular coordination, speed, and force production without negative effects on growth or maturation [10]. Beyond athletics, greater lower-body power in youth is linked to healthier body composition, better metabolic profiles, and higher physical activity levels later in life [11]. Cultivating power early may therefore serve a dual purpose: optimizing performance in the present and preserving function across the lifespan.
Why power is such a potent health signal
Neuromuscular aging impacts speed before strength, with the rate of force development and contraction speed declining more rapidly than maximal force production. This loss in rapid force capacity can compromise reactive balance, gait, and resistance to falls—abilities that are critical for maintaining independence in older age [8]. Power, however, is more than just speed; it reflects the integration of multiple physiological systems. The ability to move load quickly depends on muscle strength, tendon integrity, precise motor control, and sufficient cardiorespiratory support. This “systems check” quality likely explains why power correlates so strongly with both functional performance and survival [2,5]. CrossFit’s emphasis on functional movements performed at speed aligns closely with this biological reality. By prioritizing multi-joint, natural patterns—such as squatting, hinging, pushing, pulling, and carrying—executed at relative intensity, CrossFit reliably produces higher average power output, the metric most associated with broad, meaningful adaptation [1].
Power for the Deconditioned: Restoring Capacity from the Ground Up
For deconditioned individuals or those recovering from illness or inactivity, power training may sound intimidating—but it’s often the most essential starting point. The loss of speed and coordination typically precedes the loss of maximal strength, meaning the ability to produce force quickly is often the first to go and the last to return. Power, in this context, doesn’t mean Olympic lifts or maximal sprints; it means relearning to move with intent.
For someone who struggles to rise from a chair, a sit-to-stand with a focus on speed becomes a powerful intervention. For another, it may mean standing quickly from a half squat or carrying light objects briskly over short distances. These microbursts of fast, functional movement restore neuromuscular efficiency, coordination, and confidence—precursors to regaining independence. The key for coaches and clinicians is to scale intent, not just load. Power training for a deconditioned adult may begin with unloaded or assisted movements at higher relative velocity. Over time, external resistance, complexity, and duration can be layered in as capacity improves.
The goal is to restore the brain–body connection that governs rapid recruitment of muscle fibers and efficient joint sequencing. When approached progressively, this style of training has been shown to improve balance, gait, and even cognitive performance in older and deconditioned populations In CrossFit terms: move well first, then move faster—always relative to your ability that day.
Benchmarking Power: Making Adaptation Visible
Power training thrives on feedback. Because power is defined as work divided by time, small improvements in speed, load, or volume can be quantified and celebrated. CrossFit’s data-driven foundation makes this easy to integrate. The benchmark is not just “can you lift it?” but “can you move it faster, more efficiently, and recover well enough to do it again?”
For the everyday athlete, useful metrics include:
Average power (work ÷ time) across workouts like “Fight Gone Bad” or repeated sprint intervals.
Functional field tests such as sit-to-stand time, vertical or broad jump distance, and medicine ball throw—all validated correlates of lower-body power and functional independence.
Rate of perceived exertion (RPE) and recovery tracking to ensure intensity is sufficient to stimulate adaptation without overtraining.
Progress isn’t always linear, but trends tell the story: reduced time for the same work, improved jump or throw distance, higher loads moved at the same tempo. These data points make adaptation tangible—transforming power from a concept into a measurable health outcome. In CrossFit’s language, this is measurable, observable, and repeatable fitness applied to the science of longevity.
If you coach or care for humans, the goal should be to teach them not just to be strong, but to move load fast. That’s not just a CrossFit mantra—it’s where the best science is pointing.
Action Steps for Coaches
Measure Power Simply. Track average power: work ÷ time. Faster reps at the same load = more power.
Program Speed + Load. Prioritize functional, multi-joint patterns; progress speed, range of motion, or load gradually.
Blend Strength and Power. Pair strength days with power days (e.g., 5×5 front squat into max height box jump).
References
