Countermovement Jump (CMJ) Height ≠ Fatigue in Endurance Runners
Study Spotlight:Vertical Jumping as a Monitoring Tool in Endurance Runners: A Brief Review
(García-Pinillos et al., 2021 | PMCID: PMC8607773)
The Big Picture
CMJ height is commonly used to track neuromuscular fatigue in sprinters, team sport athletes, and even strength athletes. But should we use it the same way for endurance runners or mountain athletes?
This review says: not so fast.
Researchers examined multiple studies across marathoners, triathletes, and endurance runners doing continuous and interval running. What they found flips conventional wisdom:
- CMJ height doesn’t drop with fatigue during most endurance workouts
- In many cases, it actually increases (potentiation > fatigue)
- There’s no reliable link between CMJ height loss and internal load (like lactate or RPE) in endurance runners
So What? Here’s Why It Matters:
CMJ Height Is Not a Fatigue GaugeHigh lactate and high RPE don’t always mean lower CMJ. In endurance athletes, the stretch-shortening cycle often becomes more responsive—not less—during prolonged efforts.
Potentiation Is Real, Especially in Trained Endurance Athletes
Many trained endurance athletes display a post-activation performance enhancement (PAPE) effect—where CMJ height increases, not decreases, during or after aerobic sessions. This doesn’t mean they’re “fresh”—it means the neuromuscular system is primed rather than impaired.
The authors suggest that this response, a higher jump following the same aerobic workload, could reflect a positive chronic adaptation. Over time, if an athlete consistently shows improved CMJ performance post-session, it may indicate reduced residual fatigue or enhanced neuromuscular efficiency. In other words, the same dose creates less disruption, and the system is trending in the right direction.
Summary Table: CMJ as a Fatigue Marker in Endurance Runners
What Was Tested | Result | Takeaway for Coaches |
CMJ after submaximal intervals | Often increased (e.g. +5–8%) | Potentiation is more common than fatigue |
CMJ vs. Blood Lactate / RPE | No consistent correlation | CMJ height ≠ reliable metabolic fatigue marker |
CMJ height after marathons/triathlons | Decreased, but only in extreme fatigue states | Only useful in prolonged or maximal events |
Sprint-based protocols (sprinters) | Strong decrease in CMJ + ↑ lactate | CMJ loss is a valid fatigue marker in power sports |
Endurance athletes during intervals | No CMJ loss despite high lactate & RPE | CMJ height not valid for acute fatigue assessment |
Coach’s Bottom Line:
In most cases, we’re not using countermovement jump (CMJ) testing to chase declines in jump height as a proxy for fatigue. That model doesn’t hold up well for endurance or mountain athletes.
Instead, what matters is how force is applied and managed. How the athlete controls descent, how quickly they reverse it, and how symmetrically they load across limbs. Those are the variables that reflect movement quality and system readiness.
Jump height alone tells you very little. But the sequence that leads there: braking rate, impulse ratios, time to takeoff, and asymmetry under load offers insight into how the neuromuscular system is adapting, compensating, or responding to the demands placed on it.
However, that kind of signal only becomes useful when interpreted in context. Force plate testing doesn’t replace sound training structure or consistent athlete monitoring, it adds dimension to it. Used well, it helps refine decisions, not dictate them.
