Speed-specific Training and Ultrasound

This is an iPad-administered task (by a research assistant) that measures the flexible use of rules to govern behavior as a means of providing an index of executive function development. The DCCS is a measure of cognitive flexibility. Two target pictures are presented that vary along two dimensions (e.g., shape and color). Participants are asked to match a series of bivalent test pictures (e.g., yellow balls and blue trucks) to the target pictures, first according to one dimension (e.g., color) and then, after a number of trials, according to the other dimension (e.g., shape). "Switch" trials are also employed, in which the participant must change the dimension being matched. For example, after four straight trials the subject is correct on matching shapes, the participant may be asked to match on color on the next trial and then go back to shape, thus requiring the cognitive flexibility to quickly choose the correct stimulus.

The Flanker Test uses response inhibition to assess a subject's capacity to suppress incorrect responses within a particular context. The target (in our case an arrow) is flanked by non-target arrows that are either in the same direction as the target (congruent flankers), the opposite response (incongruent flankers), or to neither (neutral flankers).

The PSMT can test episodic memory in persons from 3 through 85. The PSMT involves presentation of sequences of pictured objects and activities in a fixed order on a computer screen and simultaneously verbally described, that the participant must remember and then reproduce over three learning trials.

The List Sorting Working Memory Test assesses working memory and is part of the NIH Toolbox Cognition Battery. List Sorting is a sequencing task requiring subjects to sort and sequence stimuli that are presented visually and auditorily. Lists may include animal to be sorted by size, foods to be sorted by size, or a combination of the two to be sorted by size.

The Toolbox Pattern Comparison Processing Speed Test is the assessment of choice to measure reaction time in older adults and is also used to measure processing speed. During the test, participants are asked to identify whether two visual patterns are the "same" or "not the same." Scores reflect the number of correct responses within a finite time frame.

Power testing will begin with a warm-up of 10 repetitions at 30% 1RM, followed by a 1-minute recovery period. A second warm-up of 5 repetitions at 30% 1RM will then be performed as rapidly as possible. Peak muscle power will then be assessed at 8 relative intensities (40, 50, 60, 70, and 80% 1RM) on the same resistance machines used for strength testing. The percentages will be randomized to reduce any order effect. For each repetition, the concentric phase will be performed as fast as possible, and the eccentric phase will be performed over 2-3 seconds. Each repetition will be verbally cued "3.2.1. Go!" This testing protocol is commonly used for power testing. Any repetition not performed properly will be repeated after a 1-minute break. Power output will be recorded from the display of each machine and cross-referenced with the electronic spreadsheets. Power testing for leg press and chest press, which are to be used as variables in our analysis, will occur before the beginning

Ultrasound images of the quadriceps femoris muscle (vastus medialis, vastus lateralis, vastus intermedius, rectus femoris) will be taken on the thigh at the two-thirds and midpoint of the length between the anterior superior iliac spine and the upper border of the patella. A LOGIQ P9 R3 Ultrasound System (GE Healthcare, Buckinghamshire, UK) and 3-12 MHz linear array transducer probe will be used, and testing will be conducted on a padded treatment table. Care will be taken to maintain the same standardized body positions and probe locations for all participants. Minimal pressure will be applied by the researcher to reduce any tissue compression that would artificially influence the results. Before acquiring measurements, subjects will rest on the examination table for five minutes to avoid any potential movement-induced stiffness. To improve acoustic contact between the probe and skin, a water-soluble transmission gel will be used on the head of the probe. Both legs will be imaged.

The Biodex 4 Dynamometer will be used for all isokinetic testing. Subjects will be asked to perform an isokinetic warmup of 10 repetitions of leg extension at 270 deg/s, be given a three-minute recovery, and then perform three maximal isokinetic quadriceps extensions at 90, 180, and 300 degrees/second using 2-minute recoveries in between sets. All results will be recorded. The repetitions producing the highest peak torque among the three efforts, and the average power for the repetitions will be used for statistical evaluation. Given the nature of isokinetic testing the resistance is at the speeds we have chosen, far below maximum.