The countermovement jump (CMJ) is a widely used method to assess neuromuscular fatigue in athletes.
But does it detect fatigue when no muscle damage is involved?
This study examines whether CMJ performance is affected by fatigue following a metabolically demanding, yet non-mechanically damaging, cycling protocol, with a focus on its relationship to prolonged low-frequency force depression (PLFFD).
Can CMJ performance detect neuromuscular fatigue after non-muscle-damaging (i.e., metabolically demanding) exercise?
What Did the Researchers Do?
- Participants: 11 recreationally active adults (9 men, 2 women).
- Protocol: Exhaustive incremental cycling to task failure (non-eccentric, metabolic fatigue).
- Assessments:
- CMJ variables: Jump height, concentric/eccentric impulse and duration, peak power/force, MRFD.
- PLFFD: Measured via electrical stimulation (10 Hz) vs. MVC (voluntary contraction).
- Time Points: Baseline, immediately post-exercise, 8, 15, 30, 60 min, 24 h, and 48 h post.
- Design: Repeated measures with randomized order of tests to minimize carryover fatigue.
Suggested Screen Shot: Figure 1 (Experimental Timeline), Figure 6 (PLFFD vs CMJ outcomes over time).
What Were the Results?
- PLFFD was significantly elevated at all time points up to 60 minutes post-exercise (p < 0.002), peaking at ~9% reduction from baseline.
- CMJ Performance: Nearly all parameters remained unchanged.
- Only concentric impulse (ConImp) dropped significantly at 0 and 8 minutes, but returned to baseline by 15 minutes.
- Key Point: Despite significant low-frequency fatigue (PLFFD), CMJ showed minimal change.
What Does This Mean?
- CMJ is insensitive to PLFFD when the fatigue is metabolic (not mechanical or muscle-damaging).
- The fatigue from this protocol likely stemmed from excitation–contraction (EC) coupling failure, not muscle damage.
- Subjective measures or direct physiological markers (e.g., MVC, PLFFD) may be more appropriate when muscle damage is absent.
Coach’s Takeaway
- Don’t assume a “normal” CMJ means no fatigue, especially after non-damaging training like long cycling bouts or aerobic conditioning.
- Use CMJ for fatigue detection after eccentric or plyometric loading, but consider other tools (e.g. subjective wellness scores) for metabolic fatigue.
- For mechanical loading, the CMJ is still a valuable tool for fatigue monitoring.
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Reference
Lindsay, O.R., & Fletcher, J.R. (2025). Countermovement jump performance after metabolically, but not mechanically demanding exercise: limited sensitivity to prolonged low-frequency force depression. European Journal of Applied Physiology.
