S106 Vol. 49 No. 5 Supplement MEDICINE & SCIENCE IN SPORTS & EXERCISE® B-07 Thematic Poster - Blood Flow a high pressure. CONCLUSIONS: Our results indicate that an elastic cuff pulled to 110% and 120% of resting arm circumference decreases brachial artery blood flow in Wednesday, May 29, 2019, 1:00 PM - 3:00 PM a pressure dependent manner. These pressure dependent decreases in blood flow were Room: CC-101A similar to that observed when a pressurized nylon cuff was inflated to 40 and 80% of the individuals resting arterial occlusion pressure. The application of a pressure relative to the initial cuff length, which is largely dependent upon arm circumference, appears 517 Chair: Kyra E. Pyke. Queen’s University, Kingston, ON, to provide one method to standardize the practical blood flow restriction pressure for Canada. future research. (No relevant relationships reported) 520 Board #3 May 29 1:00 PM - 3:00 PM Exercise Intensity and Middle Cerebral Artery 518 Board #1 May 29 1:00 PM - 3:00 PM Dynamics in Humans Imaging Transcranial Doppler: A Novel Approach to Emily Witte1, Yumei Liu1, Jaimie L. Ward1, Katie S. Kempf1, 1 2 3 Assess Cerebral Blood Flow Alicen Whitaker , Eric D. Vidoni , Jesse C. Craig , David C. 3 1 1 1 1 Poole, FACSM , Sandra A. Billinger . University of Kansas Catherine L. Jarrett , Katherine L. Shields , Ryan M. 2 1 1 2 Medical Center, Kansas City, KS. University of Kansas Broxterman , Soung Hun Park , Jayson R. Gifford , Russell S. 3 1 1 2 Alzheimer’s Disease Center, Fairway, KS. Kansas State Richardson . University to Utah, Salt Lake City, UT. Brigham University, Manhattan, KS. Young University, Provo, UT. Email: [email protected] (No relevant relationships reported) (No relevant relationships reported) Understanding the middle cerebral artery dynamic response during different exercise intensities is vital for understanding brain health and designing and evaluating Cerebral blood flow is commonly assessed in the middle cerebral artery (MCA) as exercise strategies for maximizing therapeutic potential. However, whether there is blood velocity, using non-imaging transcranial Doppler ultrasound (TCD). However, an interaction between exercise intensity and cerebrovascular kinetics is unknown. to accurately determine blood flow, both blood velocity and vessel diameter are PURPOSE: To characterize mean middle cerebral artery blood flow velocity (MCAv) critical components, and there is mounting evidence that the MCA is vasoactive. kinetics associated with two exercise work rates: low and moderate. We tested the PURPOSE: Therefore, the purpose of this study was to employ imaging TCD (ITCD), hypotheses that increasing work rate would increase the MCAv amplitude and that utilizing color flow and pulse wave velocity, as a novel approach to measure both ̇ age and estimated maximal oxygen uptake (VO2max) would be related to the MCAv MCA blood velocity and diameter to quantify cerebral blood flow. METHODS: amplitude. METHODS: Baseline values were collected for 90-seconds followed by ITCD was performed at rest in 9 healthy participants (7M/2F; 29±5 yrs) with a 6-minute exercise bout on a recumbent stepper. Heart rate, end tidal CO (P CO ), sublingual nitroglycerin (NTG, 0.8mg) and without (CON). Measurements were 2 ET 2 beat-to-beat blood pressure, and MCAV were recorded at rest and during exercise. The taken for 2 minutes prior, and for 5 minutes following NTG or sham delivery (CON). MCAv kinetics response for participants from baseline (BL) was described by the RESULTS: There was a 6-fold fall in MCA blood velocity in response to NTG (∆ response amplitude (Amp), time delay (TD), and time constant (τ). RESULTS: Sixty- -4.8±4.2 cm/s) compared to negligible fluctuations in CON (∆ -0.81±2.5 cm/s). MCA four adults completed the low and moderate intensity exercise transitions. MCAv Amp diameter increased much more in response to NTG (∆ 0.17±0.02 cm) compared to increased from rest as a function of work rate, low and moderate intensity, respectively, the basal variation in CON (∆ 0.01±0.04 cm). Interestingly, the product of this NTG- (11.8 and 14.7 cm/s; p<0.001) while no difference between work rates were observed WEDNESDAY, MAY 29, 2019 29, MAY WEDNESDAY, induced fall in MCA blood velocity and increase in MCA diameter was a significant in either TD (43.5 and 45.8 s; p=0.65) or τ (35.2 and 31.4 s; p=0.47). Age showed a increase in blood flow following NTG (∆ 159±59 ml/min) compared to CON (∆ moderate, negative association with MCAv Amp (r=-0.40 and r=-0.42; p<0.01). Higher 24±46 ml/min). CONCLUSIONS: These juxtaposed data highlight the importance ̇ estimated VO2 max demonstrated a moderate, positive correlation with MCAv Amp of measuring both MCA blood velocity and diameter when assessing cerebral blood (r=0.41 and r=0.50; p<0.01). CONCLUSION: Moderate intensity exercise induced a flow and document ITCD as a novel approach to achieve this goal. Supprted by the greater MCAv response amplitude compared to low intensity exercise. The amplitude Veterans Administration Rehabilitation Research and Development Service (E6910-R, of the initial MCAv response for both exercise intensities increased systematically E1697-R, E1433-P, E9275-L and E1572-P). with work rate whereas the TD and τ kinetics parameters were invariant. Therefore, the possibility exists that the cerebrovascular system may have protective mechanisms 519 Board #2 May 29 1:00 PM - 3:00 PM in place to avoid the more rapid responses as seen in skeletal muscle, however more Arm Circumference As A Method To Standardize The work is needed to address this hypothesis. Finally, although the MCAv Amp declines Practical Blood Flow Restriction Pressure with age, maintaining higher cardiorespiratory fitness may benefit the cerebrovascular response to exercise. Scott J. Dankel1, J Grant Mouser2, Takashi Abe1, Zachary W. 1 3 4 Bell , Samuel L. Buckner , Kevin T. Mattocks , Matthew B. 521 Board #4 May 29 1:00 PM - 3:00 PM Jessee5, Jeremy P. Loenneke1. 1The University of Mississippi, University, MS. 2Troy University, Troy, AL. 3The University of The Influence of a High Sodium Meal on South Florida, Tampa, FL. 4Lindenwood University-Belleville, Cerebrovascular Reactivity Belleveille, IL. 5University of Southern Mississippi, Hattiesburg, Kamila U. Migdal1, Austin T. Robinson1, Joseph C. Watso1, MS. Matthew C. Babcock1, Jorge M. Serrador2, William B. Farquhar, (No relevant relationships reported) FACSM1. 1University of Delaware, Newark, DE. 2Rutgers University, Newark, NJ. Practical blood flow restriction training using elastic cuffs is gaining popularity. A (No relevant relationships reported) criticism of this method is that the pressure applied and the amount of blood flow restriction induced is difficult to quantify.PURPOSE: To quantify blood flow Single high sodium (Na+) meals transiently reduce peripheral blood vessel function following the application of an elastic-cuff and compare that to what is observed in humans. Rodent models demonstrate that high dietary Na+ intake reduces middle using a more traditional pressurized nylon-cuff.Methods: 35 participants visited the cerebral artery (MCA) function. Cerebrovascular reactivity (CVR) to carbon laboratory once for testing. In a randomized order (one condition per arm), an elastic- dioxide (CO2) is a validated method for assessing the cerebrovasculature in humans. cuff (5cm wide) was applied to one arm and blood flow was measured following However, the effects of a single high dietary Na+ meal on CVR in humans is unknown. the cuff being pulled to two distinct lengths; 110% (low pressure) and 120% (high PURPOSE: We tested the hypothesis that a single high- vs low-Na+ meal impairs pressure) of the individuals resting arm circumference. The other arm followed CVR in young adults. METHODS: Nineteen healthy, normotensive adults (9M/10F; a similar protocol but used a pressurized nylon-cuff (5cm wide) inflated to 40% age: 26±4 yrs; BMI: 23.6±5.1 kg/m2; BP: 105±9/58±6 mmHg, mean±SD) participated (low pressure) and 80% (high pressure) of the individuals resting arterial occlusion in this crossover design study. We provided participants with high- (HS: 1,495 mg) pressure. RESULTS: There was a main effect of pressure (p<0.001) with blood flow and low- (LS: 138 mg) Na+ meals in randomized order. Visits were separated by one decreasing from resting in a pressure dependent manner as follows: low pressure: -27.3 week for males. We tested females in the early follicular phase of their menstrual (95% CI: -39.5, 15.1) mL/min and high pressure: -47.2 (95% CI: -64.5, -29.9) mL/ cycle. Transcranial doppler of the right MCA was assessed while participants lay min). The mean difference (95% CI) in blood flow between cuffs at a given pressure + supine. Serum Na and CVR (%ΔMCA velocity/ΔCO2) to high CO2 (hypercapnia) was -5.9 (-18.9, 7.0) % for the lower pressure and -4.0 (-13.2, 5.1) % for the higher and low CO2 (hypocapnia) were measured prior to-, 30 minutes post- and 60 minutes pressure. When the relative changes for each cuff were separated by sex, there were no post-meal. Data were analyzed using two-way repeated measures ANOVA (meal x differences in the changes from Pre. The relative difference (95% CI) between sexes time). Tukey post hoc comparisons were used when appropriate. RESULTS: Serum were as follows: -5.3 (-23.5, 12.9) % for the nylon cuff inflated to a low pressure, -1.6 Na+ was elevated on the high-Na+ meal at 30- (HS=141.2±0.3 vs LS=140.0±0.5 (-20.1, 16.8) % for nylon cuff inflated to a high pressure, 6.5 (-13.3, 26.3) % for the mmol/L, p<0.01) and 60-minutes post meal (HS=141.7±0.8 vs LS=140.2±0.6 mmol/L, elastic pulled to a low pressure, and -4.5 (-24.2, 15.1) % for the elastic cuff puled to p<0.001).