Objective: We used ultra-high field MRI to visualize cortical lesion types described by neuropathology in 16 patients with multiple sclerosis (MS) compared with 8 age-matched controls; to characterize the contrast properties of cortical lesions including T2*, T2, T1, and phase images; and to investigate the relationship between cortical lesion types and clinical data. Methods:We collected, on a 7-T scanner, 2-dimensional fast low-angle shot (FLASH)-T2*-weighted spoiled gradient-echo, T2-weighted turbo spin-echo (TSE) images (0.33 ϫ 033 ϫ 1 mm 3 ), and a 3-dimensional magnetization-prepared rapid gradient echo.Results: Overall, 199 cortical lesions were detected in patients on both FLASH-T2* and T2-TSE scans. Seven-tesla MRI allowed for characterization of cortical plaques into type I (leukocortical), type II (intracortical), and type III/IV (subpial extending partly or completely through the cortical width) lesions as described histopathologically. Types III and IV were the most frequent type of cortical plaques (50.2%), followed by type I (36.2%) and type II (13.6%) lesions. Each lesion type was more frequent in secondary progressive than in relapsing-remitting MS. This difference, however, was significant only for type III/IV lesions. T2*-weighted images showed the highest, while phase images showed the lowest, contrast-to-noise ratio for all cortical lesion types. In patients, the number of type III/IV lesions was associated with greater disability (p Ͻ 0.02 by Spearman test) and older age (p Ͻ 0.04 by Spearman test).Conclusions: Seven-tesla MRI detected different histologic cortical lesion types in our small multiple sclerosis (MS) sample, suggesting, if validated in a larger population, that it may prove a valuable tool to assess the contribution of cortical MS pathology to clinical disability. GLOSSARY ANOVA ϭ analysis of variance; BN ϭ background noise; CNR ϭ contrast-to-noise ratio; DIR ϭ double-inversion recovery; EDSS ϭ Expanded Disability Status Scale; FLAIR ϭ fluid-attenuated inversion recovery; FLASH ϭ fast low-angle shot; GM ϭ gray matter; MPRAGE ϭ magnetization-prepared rapid gradient echo; MR ϭ magnetic resonance; MS ϭ multiple sclerosis; NACGM ϭ normal-appearing cortical gray matter; RF ϭ radiofrequency; ROI ϭ region of interest; RRMS ϭ relapsingremitting multiple sclerosis; SNR ϭ signal-to-noise ratio; SPMS ϭ secondary progressive multiple sclerosis; TA ϭ time of acquisition; TE ϭ echo time; TR ϭ repetition time; TSE ϭ turbo spin-echo; WM ϭ white matter.Although cortical lesions were identified as a common finding in multiple sclerosis (MS) from the earliest pathologic studies, 1-3 their significance was underestimated until recent histopathologic data revealed that they constitute a substantial proportion of the total brain MS lesion load. 4,5 The ability of standard field strength scanners (1.5 T, 3 T) to detect and characterize cortical MS pathology is still significantly lower than neuropathology.6 Ultra-high field systems (7 T to 9.4 T) allow a 2-to 3-fold improvement in image sign...

The reliability of the reactive strength index (RSI) and time to stabilization (TTS) during maximal-effort plyometric depth jumps was examined. Twenty-two subjects performed three depth jumps from a height of 30 cm. Measures such as height of jump (JH), ground-contact time (CT), RSI, and TTS were obtained and analyzed for reliability using Cronbach alpha reliability coefficient and intraclass correlations. The JH, CT, and RSI were shown to be highly reliable from trial to trial (evidenced by high Cronbach reliability coefficients (alpha > 0.95) and high single- and average-measures intraclass correlations (>0.9). Time to stabilization was not reliable from trial to trial, as evidenced by a low Cronbach reliability coefficient (alpha < 0.7) and poor single- (<0.5) and average-measures (<0.7) intraclass correlations. The RSI was observed to be consistent for single measures, suggesting that coaches dealing with large numbers of athletes can conduct only a single trial from each depth jump height when attempting to optimize plyometric depth jump heights for their athletes. Time to stabilization could be a useful tool for strength and conditioning investigators to quantify the landing portion of plyometric exercises, but the protocol used in the current study to measure this variable did not prove to be reliable. Investigators wishing to use this measurement in such a context in future research studies may need to allow subjects appropriate habituation periods and control for arm movement during the landing phase of the exercise.

Complex training has been recommended as a method of incorporating plyometrics with strength training. Some research suggests that plyometric performance is enhanced when performed 3-4 minutes after the strength training set, whereas other studies have failed to find any complex training advantage when plyometrics are performed immediately after the strength training portion of the complex. The purpose of this study was to determine if there is an ergogenic advantage associated with complex training and if there is an optimal time for performing plyometrics after the strength training set. Subjects were 21 NCAA Division I athletes who performed a countermovement vertical jump, a set of 5 repetitions maximum (5 RM) squats, and 5 trials of countermovement vertical jump at intervals of 10 seconds and 1, 2, 3, and 4 minutes after the squat. Jump height and peak ground reaction forces were acquired via a force platform. The pre-squat jump performance was compared with the post-squat jumps. Repeated measures ANOVA determined a difference (p 0.05) was found comparing subsequent jumps (0.72-0.76 m) to the pre-squat condition (0.74 m). When comparing high to low strength individuals, there was no effect on jump performance following the squat (p > 0.05). In conclusion, complex training does not appear to enhance jumping performance significantly and actually decreases it when the jump is performed immediately following the strength training set; however, a nonsignificant trend toward improvement seemed to be present. Therefore to optimize jump performance it appears that athletes should not perform jumps immediately following resistance training. It may be possible that beyond 4 minutes of recovery performance could be enhanced; however, that was not within the scope of the current study.

The study assessed the effect of current activation potentiation by evaluating jaw clenching and its effect on the rate of force development (RFD), time to peak force (TTPF), and peak force (PF) during the countermovement jump. Fourteen subjects performed the countermovement jump on a force platform while maximally clenching their jaw on a dental vinyl mouthguard (JAW) as well as without clenching their jaw by jumping with an open mouth (NON-JAW). Results reveal that the RFD was 19.5% greater in the JAW compared with the NON-JAW condition (p < 0.05). The TTPF was 20.15% less in the JAW compared with the NON-JAW condition (p < 0.05). There were no significant differences (p = 0.60) in PF between the JAW and NON-JAW conditions. These findings indicate that concurrent activation potentiation is manifested through jaw clenching during the countermovement jump. As a result, athletes may employ this strategy of maximally clenching their jaws to gain an ergogenic advantage during the countermovement jump.

2Complex training research has indicated that 3-4 minutes may be an optimum 3 intracomplex rest interval. The purpose of this study was to determine if a heavy 4 resistive exercise causes performance enhancement of a slow stretch-shortening cycle 5 exercise and if there is an optimal rest interval. Eighteen subjects performed 6 countermovement jumps before and after a 5RM back squat lifting protocol. This 7 procedure was repeated 4 times over 2 days using rest intervals of 30 seconds, 2, 4 8 and 6 minutes. Flight time and peak ground reaction force were the dependent 9 variables. All jumps were performed on a specially constructed sledge and force 10 platform apparatus. Repeated measures ANOVA found a significant reduction in 11 flight time at the 30 second and 6 minute interval (p < 0.05). No significant difference 12 was found between men and women. Only the men showed an enhancement in jump 13 performance after the 4 minute interval. The improvement window was different for 14 each subject and an analysis of the greatest increase and decrease in flight time and 15 peak ground reaction force was conducted, showing a significant decrease for men 16 and women and a significant increase in flight time for men and peak ground reaction 17 force for women. The results suggest that complex training can benefit and/ or inhibit 18 countermovement jump performance depending on the rest interval. The individual 19 determination of the intracomplex rest interval may be necessary in the practical 20 setting. 21 22