Session ratings of perceived exertion (SRPE) during resistance training may be influenced by specific exercise parameters. The purpose of this study was to examine the influence of work rate (total work per unit time) and recording time on SRPE. Participants performed 3 exercise bouts of bench press, lat pull-down, overhead press, upright row, triceps extension, and biceps curl at 60% of predetermined 1 repetition maximum according to these protocols: (a) 3 sets × 8 repetitions (reps) × 1.5 minutes of recovery, (b) 3 sets × 8 reps × 3 minutes of recovery, and (c) 2 sets × 12 reps × 3 minutes of recovery. Session ratings of perceived exertion for the 3 × 8 × 1.5-minute recovery (5.3 ± 1.8) and 2 × 12 × 3-minute recovery trials (6.2 ± 1.7) were significantly greater vs. 3 × 8 × 3-minute recovery trial (4.2 ± 1.8). The difference approached significance between work rate-matched protocols (p = 0.08). No difference was observed between SRPE at 15 minutes (5.1 ± 1.8) vs. 30 minutes (5.2 ± 1.9) post exercise. Post-set in-task ratings of perceived exertion were higher for the 2 × 12 × 3-minute recovery trial (5.9 ± 1.4) vs. 3 × 8 × 1.5-minute recovery trial (4.8 ± 1.2) and 3 × 8 × 3-minute recovery trial (4.0 ± 1.6). The difference approached significance (p = 0.07) for the 3 × 8 × 3-minute recovery trial vs. 3 × 8 × 1.5-minute recovery trial. Session ratings of perceived exertion responded to changes in work rate with no significant difference at matched work rates, indicating that SRPE is responsive to training load. Results indicated that more proximal monitoring (15 minutes post exercise) yielded reliable estimates of SRPE increasing the practical utility of the measure.

In the originally published version of this article, Table 1 unfortunately included c.542G>A instead of c.542G>T. This mutation was correctly notated as c.

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cil~' iThe goal of this work is to develop techniques for measuring gradients in particle concentration within filled polymers, such as encapsulant. A high concentration of filler particles is added to such materials to tailor physical properties such as thermal expansion coefficient. Sedimentation and flow-induced migration of particles can produce concentration gradients that are most severe near material boundaries. Therefore, techniques for measuring local particle concentration should be accurate near boundaries. Particle gradients in an aluminafilled epoxy resin are measured with a spatial resolution of 0.2 mm using an x-ray beam attenuation technique, but an artifact related to the finite diameter of the beam reduces accuracy near the specimen's edge. Local particle concentration near an edge can be measured more reliably using microscopy coupled with image analysis. This is illustrated by measuring concentration profiles of glass particles having 40 pm median diameter using images acquired by a confocal laser fluorescence microscope. The mean of the measured profiles of volume fraction agrees to better than 3°/0 with the expected value, and the shape of the profiles agrees qualitatively with simple theory for sedimentation of monodisperse particles. Extending this microscopy technique to smaller, micron-scale filler particles used in encapsulant for microelectronic devices is illustrated by measuring the local concentration of an epoxy resin containing 0.41 volume fraction of silica.

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