To Window or Not To Window? The Effects of Window Thresholds On Shoulder Isokinetic Testing

Document Type

Article

Publication Date

6-3-2016

Publication Title

Medicine & Science in Sports & Exercise Supplemental

DOI

10.1249/01.mss.0000487154.98521.65

ISSN

1530-0315

Abstract

Common practice for isokinetic testing is to window test data within certain percentages of the target velocity. To date, particularly for the shoulder, little objective rationale for the optimal window threshold exists.

PURPOSE: To examine the effects of differing window thresholds on shoulder internal (IR) and external (ER) rotation average peak torque and range of motion.

METHODS: Fifteen healthy, young adults (18 to 30 yrs) completed dominant shoulder IR and ER rotation isokinetic testing at 60°/s and 180°/s (Biodex, Shirely, NY). Raw torque, angle and velocity data were exported from the dynamometer software and processed using a custom program that computed peak torque and ROM at seven window thresholds: no window (NW), 70%, 75%, 80%, 85%, 90% and 95% of target velocity. Speed by window analyses of variance with Bonferroni post hoc tests were conducted. Statistical significance was considered at α=.05.

RESULTS: All participants reached 95% of 60°/s for both IR and ER and 180°/s for IR, whereas 20% (n=3) failed to reach 180°/s for ER. With each window threshold increase, ROM (P≤.001, d=1.35 to 7.46) and 180°/s IR peak torque were significantly decreased (P<.001 to .032, d=1.01 to 5.53), whereas 180°/s ER peak torque significantly decreased until 90% (P <.001 to .037, d=.99 to 2.31). For 60°/s IR peak torque, NW,70%, and 75% were significantly greater than 85%, 90% and 95% (P =.004 to .027, d=1.04 to 1.29) and 80% and 85% were significantly greater than 95% (P=.014 to .017, d=1.09 to 1.12). For 60°/s ER peak torque, 95% was significantly less than all other window thresholds (P=.039 to .048, d=.96 to.99).

CONCLUSION: Even with 5% increments, windowing had very potent effects on peak torque and ROM data. These results suggest when determining peak torque from isokinetic shoulder IR and ER data at 60°/s and 180°/s, the data be windowed at 90% of the target velocity. Future research will consider the effects of windowing on total work and average power.

Comments

© 2016 American College of Sports Medicine

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