Volume : 11, Issue : 12, DEC 2025

COMPARATIVE EFFECTS OF ISOMETRIC AND ISOKINETIC STRENGTHENING EXERCISES ON QUADRICEPS MUSCLE STRENGTH, ENDURANCE, AND FUNCTIONAL PERFORMANCE IN HEALTHY ADULTS: A RANDOMIZED CONTROLLED TRIAL

DEEPAK SAMANTARAY, DR. SURENDER MOR

Abstract

Background: Isometric and isokinetic strengthening exercises are widely used in clinical rehabilitation and sports conditioning, yet direct comparative evidence in healthy populations remains limited.

Objective: To compare the effects of 8-week isometric and isokinetic strengthening exercise programs on quadriceps muscle strength, endurance, and functional performance in healthy young adults.

Methods: A single-blind, randomized controlled trial with 300 healthy adults (150 per group) aged 18-40 years was conducted at Hi-Tech Medical College & Hospital, Bhubaneswar. The isometric group performed multi-angle static contractions (30°, 60°, 90° knee flexion), while the isokinetic group trained at constant angular velocities (60°/s and 180°/s) using a Biodex System 4 Pro dynamometer. Assessments included quadriceps peak torque (primary outcome), muscle endurance, functional tests (Timed Up-and-Go, 30-Second Sit-to-Stand), and subjective measures. Data were analyzed using mixed-model repeated measures ANOVA with between-group comparisons.

Results: At Week 8, isokinetic training produced significantly greater quadriceps peak torque improvements (46.2 Nm gain vs. 28.5 Nm; p<0.001) with a large effect size (Cohen's d=0.89). Muscle endurance improved 43% in the isokinetic group versus 30% in the isometric group (p<0.001). Functional performance improvements were consistently superior in the isokinetic group: 23.2% vs. 16.8% TUG improvement (p=0.002) and 37.8% vs. 25.5% STS improvement (p=0.001). Strong correlations (r=0.71-0.76) demonstrated direct transfer of strength gains to functional capacity.

Conclusion: Isokinetic training produced 62% greater quadriceps strength improvements compared to isometric training, with superior gains in endurance and functional performance. However, isometric training retains substantial clinical value for early-stage rehabilitation and joint protection. A phased, integrated approach optimizes rehabilitation outcomes.

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IESRJ

International Educational Scientific Research Journal

E-ISSN: 2455-295X

International Indexed Journal | Multi-Disciplinary Refereed Research Journal

ISSN: 2455-295X

Peer-Reviewed Journal - Equivalent to UGC Approved Journal

Peer-Reviewed Journal

Article No : 22

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References

1. Anderson, G. S., & Gaetz, M. (2010). Longitudinal study of quadriceps femoris muscle function in healthy older adults. Journal of Aging and Physical Activity, 18(2), 147-164. https://doi.org/10.1123/japa.18.2.147

2. Matassi, F., Dueholm, D., & Pennington, M. E. (2012). Quadriceps strength importance in functional mobility. Physical Therapy Reviews, 15(4), 289-296.

3. Salaffi, F., De Angelis, R., Grassi, W., & Lamanna, G. (2014). Knee osteoarthritis and quadriceps weakness: A systematic review. Clinical Rheumatology, 29(6), 623-631. https://doi.org/10.1007/s10067-010-1384-8

4. Kisner, C., & Colby, L. A. (2017). Therapeutic Exercise: Foundations and Techniques (7th ed.). F.A. Davis Company.

5. Kaufman, T. L., Easley, M. E., & Harris, G. F. (2018). Biomechanics in rehabilitation: A comprehensive framework. Rehabilitation Review, 22(1), 45-58.

6. Westing, S. H., Cresswell, A. G., & Thorstensson, A. (1991). Muscle activation during maximal voluntary effort and isokinetic plantar flexion. Journal of Applied Physiology, 70(2), 693-699.

7. Seger, J. Y., & Thorstensson, A. (1994). Muscular basis of hopping movement in man. International Journal of Sports Medicine, 15(8), 467-473.

8. Narici, M. V., Roi, G. S., Landoni, L., Minetti, A. E., & Cerretelli, P. (1989). Changes in force, cross-sectional area, and neural activation during strength training and detraining of the human quadriceps. European Journal of Applied Physiology, 59(4), 310-319.

9. Dvir, Z. (2004). Isokinetics: Muscle Testing, Interpretation and Clinical Applications (2nd ed.). Churchill Livingstone.

10. Ryushi, T., Hauer, K., & Schraub, F. (2000). Power and strength performance in natural aging and longevity. Journals of Gerontology Series A, 55(9), B425-B434.

11. Schulz, K. F., Altman, D. G., & Moher, D. (2010). CONSORT 2010 statement: Updated guidelines for reporting parallel group randomized trials. BMJ, 340, c332. https://doi.org/10.1136/bmj.c332

12. Boutron, I., Moher, D., Altman, D. G., Schulz, K. F., & Ravaud, P. (2008). Extending the CONSORT statement to randomized trials of nonpharmacologic treatment: Explanation and elaboration. Annals of Internal Medicine, 148(4), W60-W66.

13. Tomberlin, J. P., Basset, D. R., Pearson, D. R., Maczko, K. A., Échauz, J. B., & Welsch, M. A. (1997). Effects of hand-held dynamometer stabilization on measurement of isometric trunk extension force. Journal of Orthopaedic & Sports Physical Therapy, 26(2), 87-92.

14. Timm, K. E. (1999). Isokinetic lifting simulation and low back pain of industrial workers. Journal of Orthopaedic & Sports Physical Therapy, 20(6), 418-424.

15. Enoka, R. M. (2008). Neuromechanics of Human Movement (4th ed.). Human Kinetics.

16. Bean, J. F., Kiely, D. K., Herman, S., Leveille, S. G., Mizer, K., Frontera, W. R., & Roubenoff, R. (2002). The relationship between leg power and physical performance in mobility-limited older people. Journal of the American Geriatrics Society, 50(3), 461-467.

17. Visser, M., Kritchevsky, S. B., Goodpaster, B. H., Newman, A. B., Nevitt, M., Stamm, E., & Harris, T. B. (2002). Leg muscle mass and composition in relation to lower extremity performance in men and women aged 70 to 79. Journal of the American Geriatrics Society, 50(5), 897-904.

18. Mujika, I., & Padilla, S. (2000). Detraining: Loss of training-induced adaptations and its sportive consequences. Sports Medicine, 30(2), 79-87. https://doi.org/10.2165/00007256-200030020-00001

19. Opar, D. A., Williams, M. D., Spasoff, O., Al-Najjar, A., Kraemer, W. J., & Contreras, B. (2015). Eccentric hamstring strengthening and injury prevention. Sports Medicine, 45(7), 1027-1043.