Browsing by Author "Yates, Brandon A."
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Item Dose–Response Effect of Dietary Nitrate on Muscle Contractility and Blood Pressure in Older Subjects: A Pilot Study(Oxford University Press, 2021) Gallardo, Edgar J.; Gray, Derrick A.; Hoffman, Richard L.; Yates, Brandon A.; Moorthi, Ranjani N.; Coggan, Andrew R; Kinesiology, School of Health and Human SciencesWe have recently demonstrated that dietary nitrate, a source of nitric oxide (NO) via the nitrate → nitrite → NO enterosalivary pathway, can improve muscle contractility in healthy older men and women. Nitrate ingestion has also been shown to reduce blood pressure in some, but not all, studies of older individuals. However, the optimal dose for eliciting these beneficial effects is unknown. A pilot randomized, double-blind, placebo-controlled crossover study was therefore performed to determine the effects of ingesting 3.3 mL/kg of concentrated beetroot juice containing 0, 200, or 400 µmol/kg of nitrate in 9 healthy older subjects (mean age 70 ± 1 years). Maximal knee extensor power (Pmax) and speed (Vmax) were measured ~2.5 hours after nitrate ingestion using isokinetic dynamometry. Blood pressure was monitored periodically throughout each study. Pmax (in W/kg) was higher (p < .05) after the lower dose (3.9 ± 0.4) compared to the placebo (3.7 ± 0.4) or higher dose (3.7 ± 0.4). Vmax (in rad/s) also tended to be higher (p = .08) after the lower dose (11.9 ± 0.7) compared to the placebo (10.8 ± 0.8) or higher dose (11.2 ± 0.8). Eight out of 9 subjects achieved a higher Pmax and Vmax after the lower versus the higher dose. These dose-related changes in muscle contractility generally paralleled changes in breath NO levels. No significant changes were found in systolic, diastolic, or mean arterial blood pressure. A lower dose of nitrate increases muscle speed and power in healthy older individuals, but these improvements are lost at a higher dose. Blood pressure, on the other hand, is not reduced even with a higher dose.Item Effectiveness of a Single Prolonged Aerobic Exercise Session on Executive Function Task Performance in Physically Active Adults (21-70 Years of Age)(MDPI, 2023-02-04) Yates, Brandon A.; Armstrong, Lawrence E.; Lee, Elaine C.; Unverzagt, Frederick W.; Dadzie, Ekow, Jr.; Lopez, Virgilio, III; Williamson, Keith; Vingren, Jakob L.; Orkaby, Ariela R.; Psychiatry, School of MedicineWe sought to examine the effectiveness of an acute prolonged exercise session on post-exercise executive function in physically active adults and to assess if age or pre-exercise cognitive performance was predictive of the magnitude of change in executive task performance. Self-registered cyclists were recruited prior to participating in a 161-km mass-participation cycling event. Cyclists were excluded if they had not previously participated in a similar endurance event, were young (<18 y), or were cognitively impaired (Mini CogTM < 3 units). Immediately after completing the exercise session, the time taken to complete Trail Making Test Part A and Part B (TMT A + B) was assessed. A faster time to complete the TMT A + B was observed after exercise (+8.5%; p = 0.0003; n = 62; age range = 21–70 y). The magnitude of change in TMT A + B performance (pre vs. post) was influenced by pre-exercise TMT A + B performance (r2 = 0.23, p < 0.0001), not age (r2 =0.002; p = 0.75). Prolonged exercise had a small-to-moderate effect on post-exercise compared to pre-exercise executive function task performance (Cohen’s d = 0.38–0.49). These results support the effectiveness of a single prolonged exercise bout to augment executive function in physically active adults, irrespective of age.Item Gut Reaction: Habitual Dietary Nitrate Intake as a Modulator of Skeletal Muscle Contractile Function(Elsevier, 2021) Yates, Brandon A.; Coggan, Andrew R.; Kinesiology, School of Health and Human SciencesItem Improved pulmonary function is associated with reduced inflammation after hybrid whole‐body exercise training in persons with spinal cord injury(Wiley, 2023) Yates, Brandon A.; Brown, Robert; Picard, Glen; Taylor, J. Andrew; Medicine, School of MedicineThe current study was designed to test the hypotheses that (1) reducing systemic inflammation via a 12‐week functional electrical stimulation rowing exercise training (FESRT) prescription results in augmented pulmonary function, and (2) the magnitude of improvement in pulmonary function is inversely associated with the magnitude of systemic inflammation suppression in persons with sub‐acute (≤2 years) spinal cord injury (SCI). We conducted a retrospective analysis of a randomized controlled trial (NCT#02139436). Twenty‐one participants were enrolled (standard of care (SOC; n = 9) or FESRT (n = 12)). The exercise prescription was three sessions/week at 70–85% of peak heart rate. A two‐way analysis of covariance and regression analysis was used to assess group differences and associations between pulmonary function, log transformed high‐sensitivity C‐reactive protein (hsCRPlog) and white blood cell count (WBC). Following FESRT, clinically significant improvements in forced expiratory volume in 1 s (FEV1; 0.25 (0.08–0.43) vs. −0.06 (−0.26 to 0.15) litres) and forced vital capacity (0.22 (0.04–0.39) vs. 0.08 (−0.29 to 0.12) litres) were noted and systemic WBC (−1.45 (−2.48 to −0.50) vs. 0.41 (−0.74 to 1.56) μl) levels were suppressed compared to SOC (mean change (95% confidence interval); P < 0.05). Additionally, both ΔhsCRPlog and ΔWBC were predictors of ΔFEV1 (r 2 = 0.89 and 0.43, respectively; P < 0.05). Twelve weeks of FESRT improves pulmonary function and reduces WBC in persons with sub‐acute SCI. The potency of FESRT to augment pulmonary function may depend on adequate suppression of systemic inflammation.Item Risk factors for dementia in older intensive care unit (ICU) survivors(Wiley, 2023) Wang, Sophia; Perkins, Anthony J.; Chi, Rosalyn; Yates, Brandon A.; Khan, Sikandar H.; Gao, Sujuan; Boustani, Malaz; Khan, Babar A.; Psychiatry, School of MedicineIntroduction: As the number of older intensive care unit (ICU) survivors grows, there is an urgent need to identify modifiable risk factors for post-ICU dementia. Methods: We performed a secondary data analysis of 3144 ICU patients ≥ 50 years of age without a history of dementia or severe mental illness who were screened as part of the Pharmacological Management of Delirium (PMD) study. Delirium was assessed using the Confusion Assessment Method for the ICU. Dementia was identified using International Classification of Diseases Ninth and Tenth revision codes for dementia or prescription of anti-dementia medication. Results: Average age (standard deviation) was 65.2 ± 9.5 years; 50.4% were female; and 37.3% were Black. Analyses identified stroke (adjusted hazard ratio [HR] 2.49; 95% confidence interval [CI: 1.52, 4.07], P < 0.001), and depression (adjusted HR 3.03; 95% CI [1.80, 5.10], P < 0.001) as post-ICU risk factors for dementia. Discussion: Future studies will need to examine whether interventions targeting post-ICU stroke and depression can lower dementia incidence in ICU survivors. Highlights: Risk factors for post-intensive care unit (ICU) dementia were distinct from those of Alzheimer's disease. Cardiovascular risk factors were not associated with dementia in older ICU survivors. Post-ICU stroke was associated with a higher risk of dementia in older ICU survivors. Post-ICU depression was associated with a higher risk of dementia in older ICU survivors.Item Short-term beetroot juice supplementation improves muscle speed and power but does not reduce blood pressure or oxidative stress in 65–79 y old men and women(Elsevier, 2023) Zoughaib, William S.; Hoffman, Richard L.; Yates, Brandon A.; Moorthi, Ranjani N.; Lim, Kenneth; Coggan, Andrew R.; Exercise & Kinesiology, School of Health and Human SciencesWe have previously demonstrated that acute ingestion of inorganic nitrate (NO3-)-rich beetroot juice (BRJ), a source of nitric oxide (NO) via the NO3- → nitrite (NO2-) → NO pathway, can improve muscle speed and power in older individuals. It is not known, however, whether this effect is maintained or perhaps even enhanced with repeated ingestion, or if tolerance develops as with organic nitrates, e.g., nitroglycerin. Using a double-blind, placebo-controlled, crossover design, we therefore studied 16 community-dwelling older (age 71 ± 5 y) individuals after both acute and short-term (i.e., daily for 2 wk) BRJ supplementation. Blood samples were drawn and blood pressure was measured periodically during each ∼3 h experiment, with muscle function determined using isokinetic dynamometry. Acute ingestion of BRJ containing 18.2 ± 6.2 mmol of NO3- increased plasma NO3- and NO2- concentrations 23 ± 11 and 2.7 ± 2.1-fold over placebo, respectively. This was accompanied by 5 ± 11% and 7 ± 13% increases in maximal knee extensor speed (Vmax) and power (Pmax), respectively. After daily supplementation for 2 wk, BRJ ingestion elevated NO3- and NO2- levels 24 ± 12 and 3.3 ± 4.0-fold, respectively, whereas Vmax and Pmax were 7 ± 9% and 9 ± 11% higher than baseline. No changes were observed in blood pressure or in plasma markers of oxidative stress with either acute or short-term NO3- supplementation. We conclude that both acute and short-term dietary NO3- supplementation result in similar improvements in muscle function in older individuals. The magnitudes of these improvements are sufficient to offset the decline resulting from a decade or more of aging and are therefore likely to be clinically significant.Item The influence of acute dietary nitrate supplementation on skeletal muscle fatigue and recovery in older women.(Wiley, 2023-05) Zoughaib, William S.; Hoffman, Richard L.; Yates, Brandon A.; Moorthi, Ranjani N.; Lim, Kenneth; Coggan, Andrew R.; Kinesiology, School of Health and Human SciencesOlder individuals fatigue more rapidly during, and recover more slowly from, dynamic exercise. Women are particularly vulnerable to these deleterious effects of aging, which increases their risk of falling. We have shown that dietary nitrate (NO ), a source of nitric oxide (NO) via the NO → nitrite (NO ) → NO pathway, enhances muscle speed and power in older individuals in the non-fatigued state; however, it is unclear if it reduces fatigability and/or improves recoverability in this population. Using a double-blind, placebo-controlled, crossover design, we studied 18 older (age 70 ± 4 y) women who were administered an acute dose of beetroot juice (BRJ) containing either 15.6±3.6 or <0.05 mmol of NO . Blood samples were drawn throughout each ∼3 h visit for plasma NO and NO analysis. Peak torque was measured during, and periodically for 10 min after, 50 maximal knee extensions performed at 3.14 rad/s on an isokinetic dynamometer. Ingestion of NO -containing BRJ increased plasma NO and NO concentrations by 21±8 and 4±4 fold, respectively. However, there were no differences in muscle fatigue or recovery. Dietary NO increases plasma NO and NO concentrations but does not reduce fatigability during or enhance recoverability after high intensity exercise in older women.