TY  - JOUR
A1  - Prieske, Olaf
A1  - Aboodarda, Saied J.
A1  - Sierra, Jose A. Benitez
A1  - Behm, David G.
A1  - Granacher, Urs
T1  - Slower but not faster unilateral fatiguing knee extensions alter contralateral limb performance without impairment of maximal torque output
JF  - European journal of applied physiology
N2  - The purpose of the present study was to examine the effects of unilateral fatigue of the knee extensors at different movement velocities on neuromuscular performance in the fatigued and non-fatigued leg. Unilateral fatigue of the knee extensors was induced in 11 healthy young men (23.7 +/- 3.8 years) at slower (60A degrees/s; FAT60) and faster movement velocities (240A degrees/s; FAT240) using an isokinetic dynamometer. A resting control (CON) condition was included. The fatigue protocols consisted of five sets of 15 maximal concentric knee extensions using the dominant leg. Before and after fatigue, peak isokinetic torque (PIT) and time to PIT (TTP) of the knee extensors as well as electromyographic (EMG) activity of vastus medialis, vastus lateralis, and biceps femoris muscles were assessed at 60 and 240A degrees/s movement velocities in the fatigued and non-fatigued leg. In the fatigued leg, significantly greater PIT decrements were observed following FAT60 and FAT240 (11-19%) compared to CON (3-4%, p = .002, d = 2.3). Further, EMG activity increased in vastus lateralis and biceps femoris muscle following FAT240 only (8-28%, 0.018 <= p <=.024, d = 1.8). In the non-fatigued leg, shorter TTP values were found after the FAT60 protocol (11-15%, p = .023, d = 2.4). No significant changes were found for EMG data in the non-fatigued leg. The present study revealed that both slower and faster velocity fatiguing contractions failed to show any evidence of cross-over fatigue on PIT. However, unilateral knee extensor fatigue protocols conducted at slower movement velocities (i.e., 60A degrees/s) appear to modulate torque production on the non-fatigued side (evident in shorter TTP values).
KW  - Electromyography
KW  - Cross-over fatigue
KW  - Isokinetic
KW  - Movement velocity
KW  - Motor function
KW  - Central activation
Y1  - 2017
U6  - https://doi.org/10.1007/s00421-016-3524-6
SN  - 1439-6319
SN  - 1439-6327
VL  - 117
SP  - 323
EP  - 334
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Müller, Steffen
A1  - Stoll, Josefine
A1  - Müller, Juliane
A1  - Mayer, Frank
T1  - Validity of isokinetic trunk measurements with respect to healthy adults, athletes and low back pain patients
JF  - Isokinetics and exercise science : official journal of the European Isokinetic Society
N2  - Background: Isokinetic measurements are widely used to assess strength capacity in a clinical or research context. Nevertheless, the validity of isokinetic measures for identifying strength deficits and the evaluation of therapeutic process regarding different pathologies is yet to be established. Therefore, the purpose of this review is to evaluate the validity of isokinetic measures in a specific case: that of muscular capacity in low back pain (LBP).
 Methods: A literature search (PubMed; ISI Web of Knowledge; The Cochrane Library) covering the last 10 years was performed. Relevant papers regarding isokinetic trunk strength measures in healthy and patients with low back pain (PLBP) were searched. Peak torque values [Nm] and peak torque normalized to body weight [Nm/kg BW] were extracted for healthy and PLBP. Ranked mean values across studies were calculated for the concentric peak torque at 60 degrees/s as well as the flexion/extension (F/E) ratio.
 Results: 34 publications (31 flexion/extension; 3 rotation) were suitable for reporting detailed isokinetic strength measures in healthy or LBP (untrained adults, adolescents, athletes). Adolescents and athletes were different compared to normal adults in terms of absolute trunk strength values and the F/E ratio. Furthermore, isokinetic measures evaluating therapeutic process and isokinetic rehabilitation training were infrequent in literature (8 studies).
 Conclusion: Isokinetic measurements are valid for measuring trunk flexion/extension strength and F/E ratio in athletes, adolescents and (untrained) adults with/without LBP. The validity of trunk rotation is questionable due to a very small number of publications whereas no reliable source regarding lateral flexion could be traced. Therefore, isokinetic dynamometry may be utilized for identifying trunk strength deficits in healthy adults and PLBP.
KW  - Isokinetic
KW  - validity
KW  - low back pain
KW  - peak torque
KW  - trunk
Y1  - 2012
U6  - https://doi.org/10.3233/IES-2012-00482
SN  - 0959-3020
VL  - 20
IS  - 4
SP  - 255
EP  - 266
PB  - IOS Press
CY  - Amsterdam
ER  -