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.
Prepubescent Heart Rate Response to Indoor Play
Michael Whitehurst, Denise R. Groo, and Lee E. Brown
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.
Maintenance of Velocity and Power With Cluster Sets During High-Volume Back Squats
James J. Tufano, Jenny A. Conlon, Sophia Nimphius, Lee E. Brown, Laurent B. Seitz, Bryce D. Williamson, and G. Gregory Haff
To compare the effects of a traditional set structure and 2 cluster set structures on force, velocity, and power during back squats in strength-trained men.
Twelve men (25.8 ± 5.1 y, 1.74 ± 0.07 m, 79.3 ± 8.2 kg) performed 3 sets of 12 repetitions at 60% of 1-repetition maximum using 3 different set structures: traditional sets (TS), cluster sets of 4 (CS4), and cluster sets of 2 (CS2).
When averaged across all repetitions, peak velocity (PV), mean velocity (MV), peak power (PP), and mean power (MP) were greater in CS2 and CS4 than in TS (P < .01), with CS2 also resulting in greater values than CS4 (P < .02). When examining individual sets within each set structure, PV, MV, PP, and MP decreased during the course of TS (effect sizes 0.28–0.99), whereas no decreases were noted during CS2 (effect sizes 0.00–0.13) or CS4 (effect sizes 0.00–0.29).
These results demonstrate that CS structures maintain velocity and power, whereas TS structures do not. Furthermore, increasing the frequency of intraset rest intervals in CS structures maximizes this effect and should be used if maximal velocity is to be maintained during training.
Effect of Rest Interval on Neuromuscular and Metabolic Responses Between Children and Adolescents
Martim Bottaro, Lee E. Brown, Rodrigo Celes, Saulo Martorelli, Rodrigo Carregaro, and José Carlos de Brito Vidal
The purpose of this study was to compare the effect of different rest intervals and contraction velocities on muscle recovery following resistance exercise. 18 children (11.1 ± 0.52 yrs) and 19 adolescents (15.8 ± 0.49 yrs) performed three sets of 10 isokinetic repetitions at 60°/s and 180°/s. The work-to-rest ratio (W/R) was 1:2 and 1:4 for 60°/s, and 1:6 and 1:12 for 180°/s. ANOVA revealed that children demonstrated no significant decline in PT from the first to third set with any rest interval, but there was a significant (p < .05) decline for adolescents when a W/R of 1:2, 1:4 and 1:6 were used. Adolescents demonstrated significantly greater blood lactate (BLa) concentrations than children after three sets of resistance exercise. The present study indicates that adolescents may require longer rest intervals to recover full PT when compared with children.
Cluster Sets: Permitting Greater Mechanical Stress Without Decreasing Relative Velocity
James J. Tufano, Jenny A. Conlon, Sophia Nimphius, Lee E. Brown, Harry G. Banyard, Bryce D. Williamson, Leslie G. Bishop, Amanda J. Hopper, and G. Gregory Haff
To determine the effects of intraset rest frequency and training load on muscle time under tension, external work, and external mechanical power output during back-squat protocols with similar changes in velocity.
Twelve strength-trained men (26.0 ± 4.2 y, 83.1 ± 8.8 kg, 1.75 ± 0.06 m, 1.88:0.19 one-repetition-maximum [1RM] body mass) performed 3 sets of 12 back squats using 3 different set structures: traditional sets with 60% 1RM (TS), cluster sets of 4 with 75% 1RM (CS4), and cluster sets of 2 with 80% 1RM (CS2). Repeated-measures ANOVAs were used to determine differences in peak force (PF), mean force (MF), peak velocity (PV), mean velocity (MV), peak power (PP), mean power (MP), total work (TW), total time under tension (TUT), percentage mean velocity loss (%MVL), and percentage peak velocity loss (%PVL) between protocols.
Compared with TS and CS4, CS2 resulted in greater MF, TW, and TUT in addition to less MV, PV, and MP. Similarly, CS4 resulted in greater MF, TW, and TUT in addition to less MV, PV, and MP than TS did. There were no differences between protocols for %MVL, %PVL, PF, or PP.
These data show that the intraset rest provided in CS4 and CS2 allowed for greater external loads than with TS, increasing TW and TUT while resulting in similar PP and %VL. Therefore, cluster-set structures may function as an alternative method to traditional strength- or hypertrophy-oriented training by increasing training load without increasing %VL or decreasing PP.