Yong-Hao Pua1, Peck-Hoon Ong2, Jia-Ying Ho2, Adam L Bryant3, Kate E Webster4, Ross A Clark5. 1. Department of Physiotherapy, Singapore General Hospital, Outram Road, Singapore, 169608, Singapore. puayonghao@gmail.com. 2. Department of Physiotherapy, Singapore General Hospital, Outram Road, Singapore, 169608, Singapore. 3. Department of Physiotherapy, The University of Melbourne, Melbourne, Australia. 4. School of Health Sciences Research, La Trobe University, Melbourne, Australia. 5. School of Exercise Science, Australian Catholic University, Melbourne, Australia.
Abstract
PURPOSE: Contrary to the ample data available regarding the functional significance of isokinetic knee strength in patients with anterior cruciate ligament deficiency (ACLD), much less is known about the functional significance of isokinetic knee steadiness. This cross-sectional study aimed to evaluate, in patients with ACLD, the independent impact of isokinetic quadriceps and hamstrings torque steadiness on single-leg hop performance. METHODS: Eighty-seven patients with unilateral ACLD participated. Patients performed isokinetic quadriceps and hamstrings steadiness and strength testing at 60°/s on an isokinetic dynamometer. Muscle steadiness and strength were represented by the wavelet-derived mean instantaneous frequency and peak value of the torque-time curves, respectively. To measure hop performance, patients performed a single-leg hop for distance and a 6-m single-leg hop for velocity. RESULTS: One of two patients [n = 45 (51 %)] had a 10 % or greater difference in knee torque frequency levels between the ACLD and contralateral knees. In multivariable models adjusted for age, sex, knee pain, and knee strength, hamstrings steadiness was significantly related with hop velocity whilst quadriceps steadiness was significantly related with both hop distance and velocity. Variance decomposition analyses suggested that quadriceps steadiness was similar in importance to hamstrings strength on hop distance and velocity. CONCLUSIONS: In patients with ACLD, isokinetic knee steadiness deficits were common and were independently associated with single-leg hop performance. Knee torque steadiness-a heretofore understudied variable-may prove a useful adjunct to conventional peak torque measurements by offering additional information to researchers and rehabilitation professionals about muscle performance and neuromuscular knee control. LEVEL OF EVIDENCE: Prognostic studies, Level III.
PURPOSE: Contrary to the ample data available regarding the functional significance of isokinetic knee strength in patients with anterior cruciate ligament deficiency (ACLD), much less is known about the functional significance of isokinetic knee steadiness. This cross-sectional study aimed to evaluate, in patients with ACLD, the independent impact of isokinetic quadriceps and hamstrings torque steadiness on single-leg hop performance. METHODS: Eighty-seven patients with unilateral ACLD participated. Patients performed isokinetic quadriceps and hamstrings steadiness and strength testing at 60°/s on an isokinetic dynamometer. Muscle steadiness and strength were represented by the wavelet-derived mean instantaneous frequency and peak value of the torque-time curves, respectively. To measure hop performance, patients performed a single-leg hop for distance and a 6-m single-leg hop for velocity. RESULTS: One of two patients [n = 45 (51 %)] had a 10 % or greater difference in knee torque frequency levels between the ACLD and contralateral knees. In multivariable models adjusted for age, sex, knee pain, and knee strength, hamstrings steadiness was significantly related with hop velocity whilst quadriceps steadiness was significantly related with both hop distance and velocity. Variance decomposition analyses suggested that quadriceps steadiness was similar in importance to hamstrings strength on hop distance and velocity. CONCLUSIONS: In patients with ACLD, isokinetic knee steadiness deficits were common and were independently associated with single-leg hop performance. Knee torque steadiness-a heretofore understudied variable-may prove a useful adjunct to conventional peak torque measurements by offering additional information to researchers and rehabilitation professionals about muscle performance and neuromuscular knee control. LEVEL OF EVIDENCE: Prognostic studies, Level III.
Authors: Bente R Jensen; Annesofie T Olesen; Mogens T Pedersen; Jens H Kristensen; Lars Remvig; Erik B Simonsen; Birgit Juul-Kristensen Journal: Muscle Nerve Date: 2013-08-30 Impact factor: 3.217
Authors: Malachy P McHugh; Timothy F Tyler; Michael G Browne; Gilbert W Gleim; Stephen J Nicholas Journal: Am J Sports Med Date: 2002 May-Jun Impact factor: 6.202