{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,28]],"date-time":"2026-04-28T14:25:39Z","timestamp":1777386339699,"version":"3.51.4"},"reference-count":28,"publisher":"SAGE Publications","issue":"5","license":[{"start":{"date-parts":[[1989,9,1]],"date-time":"1989-09-01T00:00:00Z","timestamp":620611200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Am J Sports Med"],"published-print":{"date-parts":[[1989,9]]},"abstract":"<jats:p>Previous studies have compared the torque production of the knee flexors and extensors and developed a \"hamstring-quadricep\" ratio. Collectively, these studies indicate that the ratio of strength between the knee flexors and extensors is a function of test speed, with the ratio increasing at the faster test speeds. Unfortu nately, these studies have employed the peak torque isokinetic method for making measurements. This tech nique suffers from a number of problems that are biomechanical and physiological in nature. Conse quently, in this study, we employed comparisons of the in vivo force-velocity relationship using an angle-specific method and a gravitational correction factor to more accurately determine flexor-extensor ratios and to bet ter describe any variations occurring as a function of test speed. Nine male subjects volunteered to partici pate in this study. Each of the subjects participated in two test sessions. Subjects were tested at six angular velocities of 0, 48, 96, 144, 192, 240 deg\/sec. At these respective test speeds, the mean flexor torques were 95.0, 94.8, 84.1, 66.2, 56.2, and 49.2 Nm, respectively. The corresponding values for the knee extensors were 252.2, 246.5, 220.7, 184.5, 161.9, and 146.4 Nm. Normalization of these torque-velocity relationships demonstrated that the in vivo force-velocity relation ships of the two muscle groups are similar at slow speeds, but become disparate at higher velocities. When examining flexor-extensor torque ratios at the various test speeds, it was found that there were significant differences (P &lt; 0.01). The mean values for the flexors expressed as a percent of knee extensor torque were 37.5%, 38.2%, 38.2%, 35.9%, 34.5%, and 33.4% at speeds of 0, 48, 96, 144, 192, and 240 deg\/ sec, respectively.<\/jats:p>","DOI":"10.1177\/036354658901700503","type":"journal-article","created":{"date-parts":[[2007,6,21]],"date-time":"2007-06-21T20:46:52Z","timestamp":1182458812000},"page":"607-611","source":"Crossref","is-referenced-by-count":34,"title":["The in vivo force-velocity relationship of the knee flexors and extensors"],"prefix":"10.1177","volume":"17","author":[{"given":"Carlos A.","family":"Prietto","sequence":"first","affiliation":[{"name":"Neuromuscular Research Laboratory, Division of Orthopaedics, Department of Surgery, College of Medicine, University of California, lrvine, California"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Vincent J.","family":"Caiozzo","sequence":"additional","affiliation":[{"name":"Neuromuscular Research Laboratory, Division of Orthopaedics, Department of Surgery, College of Medicine, University of California, lrvine, California"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"179","published-online":{"date-parts":[[1989,9,1]]},"reference":[{"key":"atypb1","unstructured":"Alexander RM , Vernon A.: The dimensions of knee and ankle muscles and the forces they exert J Human Mov Studies 1: 115-123, 1975"},{"key":"atypb2","doi-asserted-by":"publisher","DOI":"10.1113\/jphysiol.1954.sp005044"},{"key":"atypb3","doi-asserted-by":"crossref","unstructured":"Burkett LN: Causative factors in hamstnng strains. Med Sci Sport 2: 39-42, 1970","DOI":"10.1249\/00005768-197002010-00010"},{"key":"atypb4","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1981.51.3.750"},{"key":"atypb5","doi-asserted-by":"crossref","unstructured":"Caiozzo VJ, Barnes WS, Prietto CA, et al: The affect of isometric precontractions on the slow velocity-high force region of the in vivo force-velocity relationship. Med Sci Sports Exerc 13: 128 , 1981","DOI":"10.1249\/00005768-198101320-00296"},{"key":"atypb6","unstructured":"Caiozzo VJ, Black KS, Prietto CA, et al: A comparison of two isokinetic methods used for determining the in vivo force-velocity relationship of human muscle. Int J Sports Med 4: 141, 1983"},{"key":"atypb7","doi-asserted-by":"crossref","unstructured":"Costill DL, Coyle EF, Fink WF, et al: Adaptions in skeletal muscle following strength training J Appl Physiol Respirat Environ Exerc Physiol 46: 96-99, 1979","DOI":"10.1152\/jappl.1979.46.1.96"},{"key":"atypb8","unstructured":"Fugl-Meyer A. , Nordin G., Sjostrom M., et al: Achilles biofeedback. Scand J Rehab Med 11: 37-44, 1979"},{"key":"atypb9","doi-asserted-by":"publisher","DOI":"10.1111\/j.1748-1716.1985.tb07653.x"},{"key":"atypb10","unstructured":"Gilliam TB, Sady SP, Freedson PS, et al: lsokinetic torque levels for high school football players. Arch Phys Med Rehab 60: 110-114, 1979"},{"key":"atypb11","unstructured":"Goshn BR, Chartens J.: lsokinetic dynomonetry: Normative data for clinical use in lower extremity (knee) cases. Scand J Rehab Med 11: 105-109, 1979"},{"key":"atypb12","doi-asserted-by":"publisher","DOI":"10.2106\/00004623-198466050-00012"},{"key":"atypb13","doi-asserted-by":"crossref","unstructured":"Gregor RJ, Edgerton VR, Perrine JJ, et al. Torque-velocity relationships and muscle fiber composition in elite female athletes J Appl Physiol Respirat Environ Exerc Physiol 47 388-392, 1979","DOI":"10.1152\/jappl.1979.47.2.388"},{"key":"atypb14","doi-asserted-by":"crossref","unstructured":"Hinson MN, Smith WC, Funk S. lsokinetics: A clarification. Res Q 50: 30-35, 1979","DOI":"10.1080\/10671315.1979.10615576"},{"key":"atypb15","doi-asserted-by":"crossref","unstructured":"Johnson MA, Polgar J., Weightman D., et al: Data on the distribution of fiber types in thirty-six human muscles. An autopsy study. J Neurol Sci 18: 111-129, 1973","DOI":"10.1016\/0022-510X(73)90023-3"},{"key":"atypb16","unstructured":"Jorgensen K.: Force-velocity relationship in human elbow flexors and extensors, in Komi PV (ed): International Series on Biomechanics. Baltimore, University Park Press, 1976, pp 145-151"},{"key":"atypb17","unstructured":"Klafs CE, Arnheim DD: Modern Principles of Athletic Training: The Science of Injury Prevention and Care. St. Louis, CV Mosby, 1973"},{"key":"atypb18","unstructured":"Lesmes GR, Costlll DL, Coyle EF, et al: Muscle strength and power changes during maximal isokinetic training. Med Sci Sports 10: 266-269, 1978"},{"key":"atypb19","unstructured":"Nie NH, Hull CH, Jenkins JG: Statistical Package for the Social Sciences. Second edition. New York, McGraw Hill"},{"key":"atypb20","unstructured":"Perrine JJ, Edgerton VR Muscle force-velocity and power-velocity relationships under isokmetic loading . Med Sci Sports 10. 159-166, 1978"},{"key":"atypb21","doi-asserted-by":"publisher","DOI":"10.1177\/036354658301100401"},{"key":"atypb22","doi-asserted-by":"publisher","DOI":"10.1113\/jphysiol.1969.sp008923"},{"key":"atypb23","doi-asserted-by":"publisher","DOI":"10.1177\/036354658401200308"},{"key":"atypb24","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1976.40.1.12"},{"key":"atypb25","doi-asserted-by":"publisher","DOI":"10.1097\/00003086-198310000-00042"},{"key":"atypb26","doi-asserted-by":"crossref","unstructured":"Wickiewicz TL, Roy RR, Powell PL, et al. Muscle architecture and force-velocity relationships in humans. J Appl Physiol Respirat Environ Exerc Physiol 57: 435-443, 1984","DOI":"10.1152\/jappl.1984.57.2.435"},{"key":"atypb27","doi-asserted-by":"publisher","DOI":"10.1007\/BF00422127"},{"key":"atypb28","doi-asserted-by":"crossref","unstructured":"Zahalak GI, Duggy J., Stewart PA, et al: Partially activated human skeletal muscle: An experimental investigation of force, velocity, and EMG. J Appl Mech 98: 81-86, 1976","DOI":"10.1115\/1.3423800"}],"container-title":["The American Journal of Sports Medicine"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1177\/036354658901700503","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1177\/036354658901700503","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,28]],"date-time":"2026-04-28T09:35:41Z","timestamp":1777368941000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.sagepub.com\/doi\/10.1177\/036354658901700503"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1989,9]]},"references-count":28,"journal-issue":{"issue":"5","published-print":{"date-parts":[[1989,9]]}},"alternative-id":["10.1177\/036354658901700503"],"URL":"https:\/\/doi.org\/10.1177\/036354658901700503","relation":{},"ISSN":["0363-5465","1552-3365"],"issn-type":[{"value":"0363-5465","type":"print"},{"value":"1552-3365","type":"electronic"}],"subject":[],"published":{"date-parts":[[1989,9]]}}}