Plyometric exercise performance metrics like vertical jumps may not accurately reflect your strength gains, according to new research. A comprehensive meta-analysis published in the Iranian Journal of Public Health in November 2025 reveals that while grip strength improves significantly after muscle-strengthening programs, plyometric exercise performance measures like jump tests show minimal gains — challenging decades of fitness testing assumptions.
The Problem With Jump Tests
For years, fitness professionals and coaches have relied on vertical jump and standing long jump tests as primary indicators of lower body power and overall muscle strength development. These tests are easy to administer, require minimal equipment, and seem intuitive — if you’re getting stronger, you should jump higher, right?
Not necessarily, according to the research. The systematic review analyzed 13 studies involving 496 healthy young adults who participated in various muscle-strengthening programs, including plyometric exercise routines and resistance training. The results were surprising: while participants showed significant improvements in grip strength, their jump performance barely changed.
This finding contradicts the common assumption that jump performance directly reflects muscle strength gains. Many gym-goers and athletes use jump height as their primary progress metric, assuming that increased jumping ability equals increased strength. The research suggests this equation is flawed.
What the Meta-Analysis Actually Found
The study, led by researchers from Korea National University of Education and Kongju National University, calculated effect sizes for three key measurements: grip strength, standing long jump, and vertical jump. The findings paint a clear picture.
Grip strength showed a substantial improvement with an effect size of -1.36 (95% confidence interval: -2.11 to -0.62), indicating a large, statistically significant gain. In contrast, standing long jump performance showed only a small effect size of -0.28 (95% CI: -0.51 to -0.05), and vertical jump showed -0.35 (95% CI: -0.52 to -0.19). Neither jump test reached statistical significance.
This doesn’t mean plyometric exercise routines are ineffective. It means that jump tests may not be the most sensitive tools for measuring strength gains from general muscle-strengthening programs. The distinction matters for anyone tracking their fitness progress.
Why Grip Strength Outperforms Jump Tests
The researchers explain that grip strength serves as a more reliable proxy for systemic muscle strength because it’s less influenced by skill, technique, and neuromuscular coordination. Jumping is a complex movement pattern that requires coordination, timing, and practice — factors that can mask underlying strength improvements.
Think of it this way: if you’ve never practiced jumping, your first few weeks of strength training might improve your raw muscle power, but your technique hasn’t adapted yet. The jump test measures the combination of strength and skill, so early strength gains get lost in the noise of motor learning.
Grip strength, by contrast, is a simpler measurement. You squeeze the dynamometer as hard as you can. There’s minimal technique involved, making it a purer measure of muscle force production. This simplicity is precisely what makes it more reliable for tracking strength changes over time.
Practical Implications for Your Training
This research has important implications for how you track your fitness progress. If you’re following a muscle-strengthening program and using jump tests as your primary progress metric, you might conclude the program isn’t working when it actually is.
Consider incorporating grip strength testing into your progress tracking routine. A handheld dynamometer is affordable and portable, making it easy to test yourself regularly. More importantly, grip strength has been linked to numerous health outcomes beyond just muscle power — research associates it with longevity, cardiovascular health, and overall functional capacity.
That said, if your training goals specifically include improving jump performance for sports like basketball, volleyball, or track and field, then jump tests remain relevant. But for general strength tracking, grip strength provides a clearer signal of actual muscle strength development.
Understanding the Neuromuscular Component
The gap between strength gains and jump performance improvements highlights the role of neuromuscular adaptation in complex movements. When you start a new strength program, your nervous system needs time to learn how to coordinate multiple muscle groups efficiently. This learning curve affects performance on skill-dependent tests like jumps.
Research in motor learning shows that beginners often experience strength gains before visible improvements in performance tasks. The nervous system becomes more efficient at recruiting muscle fibers, improving coordination, and reducing inhibitory signals — all of which increase force production without immediately translating to better jump height.
This explains why the meta-analysis found significant grip strength improvements but not significant jump improvements. Grip strength requires minimal coordination, so strength gains show up immediately. Jump performance requires complex coordination, so strength gains take longer to manifest in test results.
Limitations and Context
The meta-analysis focused on young, healthy adults, so results may differ for older populations or clinical groups. The researchers also noted significant heterogeneity between studies (I² = 60% for grip strength), suggesting that program design, duration, and intensity all influence outcomes.
Additionally, the study examined short-term adaptations. Longer training programs might eventually produce significant jump improvements as technique catches up with strength gains. The research doesn’t dismiss plyometric exercise value — it simply questions whether jump tests are the best measurement tool for general strength programs.
Plyometric Exercise Performance: Key Takeaways for Tracking Fitness Progress
- Jump tests (vertical jump, standing long jump) may not accurately reflect strength gains from general muscle-strengthening programs
- Grip strength shows significant, reliable improvements after strength training and serves as a better proxy for overall muscle strength
- Jump performance is influenced by technique and coordination, which can mask underlying strength improvements
- Consider adding grip strength testing to your progress tracking routine for clearer feedback
- If your goal is sport-specific jump performance, continue using jump tests — but understand they measure skill and strength combined
- For general fitness tracking, simpler measurements often provide more reliable signals than complex movement tests
Related on Active Arabia: what the research says about high-intensity workouts and science-backed exercises that actually work.
Sources
- Moon J, So J, Jeon Y, Kim S. “The Assessment of Muscle Strength for Standing Long Jump and Vertical Jump: Focusing on Muscle-Strengthening Programs: A Systematic Review and Meta-Analysis.” Iranian Journal of Public Health. 2025 Nov;54(11):2298-2312. doi: 10.18502/ijph.v54i11.20378. PMC13348738.
Disclaimer
This article is for educational purposes only and does not constitute medical or fitness advice. Consult with a qualified healthcare provider or certified fitness professional before starting any new exercise program or making changes to your training routine.
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