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Prepubescent Heart Rate Response to Indoor Play

Michael Whitehurst, Denise R. Groo, and Lee E. Brown

Indoor play for pay centers (PPCs) have become very popular over the last decade. Due to the group format and physical design, the PPC promotes fastpaced large muscle activity that appears to increase the heart rate of prepubescent participants. The purpose of this study was to measure children’s heart rate response to self-directed play at a PPC. Fourteen boys and girls (age = 7.8 ± 1.8 years) participated in a treadmill test to determine their maximal heart rate (MHR). On a separate day these same children played freely for 20 min over a 5,000 square foot multilevel PPC while their heart rate was monitored. The average MHR obtained in the laboratory was 204 ± 1.3 bpm, while the average heart rate during free play was 158 ± 38.5 or 77% of the MHR observed in the laboratory. These results suggest that the PPC promotes an increase in heart rate among self-directed prepubescent subjects.

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Bilateral Isokinetic Knee Rehabilitation Following Bilateral Total Knee Replacement Surgery

Lee E. Brown, Michael Whitehurst, and David N. Buchalter

A 67-year-old male underwent bilateral total knee replacement surgery and was subsequently placed on a bilateral isokinetic knee rehabilitation program. Isokinetic knee testing was performed on unilateral dominant (UD; right) and nondominant (UND; left) limbs as well as bilateral limbs (BLs) before and after a three-times-per-week, 8-week protocol during which the patient followed a bilateral isokinetic velocity spectrum (60 to 300°/s) rehabilitation program. The protocol was made possible by the introduction of a new bilateral isokinetic knee attachment developed by the authors. The BL extension and flexion peak torque increased 41% and 51% at 60°/s, respectively. The UD and UND extension peak torque increased 22% and 37%, respectively, while flexion peak torque increased 68% and 52%, respectively. The bilateral deficit decreased with increasing velocity for both extension and flexion. These results demonstrate that a bilateral isokinetic approach to rehabilitation may be a legitimate technique to increase knee extension and flexion peak torque both unilaterally and bilaterally following bilateral total knee replacement surgery.

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Validity of the Open Barbell and Tendo Weightlifting Analyzer Systems Versus the Optotrak Certus 3D Motion-Capture System for Barbell Velocity

Jacob A. Goldsmith, Cameron Trepeck, Jessica L. Halle, Kristin M. Mendez, Alex Klemp, Daniel M. Cooke, Michael H. Haischer, Ryan K. Byrnes, Robert F. Zoeller, Michael Whitehurst, and Michael C. Zourdos

Purpose: To examine the validity of 2 linear position transducers, the Tendo Weightlifting Analyzer System (TWAS) and Open Barbell System (OBS), compared with a criterion device, the Optotrak Certus 3-dimensional motion-capture system (OC3D). Methods: A total of 25 men (age, 25 [3] y; height, 174.0 [6.7] cm; body mass, 89.0 [14.7] kg; squat 1-repetition maximum [1RM], 175.8 [34.7] kg) with ≥2 y of resistance-training experience completed a back 1RM and 1 set to failure at 70% of 1RM. Average concentric velocity (ACV) and peak concentric velocity (PCV) were recorded by all 3 devices during the final warm-up set, all 1RM attempts, and every repetition during the 70% set. Results: In total, 575 samples were obtained. Bland–Altman plots, mountain plots, a 1-way analysis of variance, SEM, and intraclass correlation coefficients were used to analyze validity. The analysis of variance showed no difference (P = .089) between devices for ACV. However, for PCV, TWAS was significantly different (ie, inaccurate) from OC3D (P < .001) and OBS (P = .001), but OBS was similar (P = .412) to OC3D. For ACV, intraclass correlation coefficients were higher for OBS than for TWAS. Bland–Altman plots showed agreement for ACV for both devices against OC3D but large limits of agreement for PCV for both devices. Mountain plots showed valid ACV for both devices, however, but slightly greater ACV and PCV accuracy with OBS than TWAS. Conclusions: Both devices may provide valid ACV measurements, but some metrics suggest more accurate ACV with OBS vs TWAS. For PCV, neither device is particularly accurate; however, OBS seems to be more accurate than TWAS.