Multidimenstional Balance in Youth with Visual Impairments

This dissertation consists of three studies which examined multidimensional balance in youth (≤ 21 years; Individuals with Disabilities Education Act, 2004) with visual impairments (VIs) using the Brief-Balance Evaluation Systems Test (Brief- BESTest). These studies have the potential to inform (adapted) physical education curricula and therapeutic/rehabilitative practices by providing novel understandings of balance performance in youth with VIs. If identified as a meaningful mechanism of action, the assessment and development of multidimensional balance in youth with VIs should be given elevated status by practitioners. Thus, the purpose of this dissertation was to investigate multidimensional balance in youth with VIs. The purpose of Study 1 was to examine the construct and convergent validity of the Brief-BESTest scores in youth with VIs. One-hundred and one youth with VIs (nboys =57) aged 8.7 to 20.4 years (M = 13.91 ± 2.82) completed the Brief-BESTest, the anterior reach of the Lower Quarter Y-Balance Test, the 360-degree turn test, inertial postural sway during quiet bipedal stance, and the Activities-specific Balance Confidence Scale. Favorable results were uncovered for the internal consistently reliability (ω = .87) and Spearman inter-item correlations (.18 to .73) for Brief-BESTest item scores. A one-factor minimum residual exploratory factor analysis using oblimin rotation was supported. Using seven of the eight Brief-BESTest (i.e., one bilaterally scored item [reactive postural response to the left side] was removed due to minor multicollinearity issues) and mean and variance-adjusted weighted least squares confirmatory factor analyses, a two-factor (i.e., static and dynamic balance) model was accepted based on measures of global and local fit. Using Spearman correlations, the Brief-BESTest total scores significantly correlated (i.e., converged) with all other balance assessment total scores (-.36 to .67). These results confirmed that Brief-BESTest scores had satisfactory construct and convergent validity in youth with VIs. The purpose of Study 2 was to compare Brief-BESTest scores between youth with and without VIs. Two-hundred and eighty-seven youth with (nVI = 129) and without VIs aged 8.7 to 20.4 years (M = 13.80 ± 2.32) completed the Brief-BESTest. A one-way analysis of variance (ANOVA) suggested youth with VIs had lower total Brief-BESTest scores (F = 225.13, p \u3c .001, ω² = .44). Concerning the eight individual Brief-BESTest items, a one-way multivariate analysis of variance (MANOVA) was statistically significant (F = 43.07, p \u3c .001, V = .55). Games-Howell post hoc analyses highlighted significantly impaired balance performance in youth with VIs for all Brief-BESTest items except for the sensory orientation task (i.e., static bipedal stance on foam with eyes closed). The largest effect sizes (ω²) were for the anticipatory postural adjustment (i.e., right [.46] and left [.50] single leg stances; static balance) and biomechanical constraint (i.e., hip/trunk lateral strength [.26]; static balance) systems. After subsetting the youth with VIs within the sample, an analysis of covariance (ANCOVA) suggested that both degree of vision (F = 3.60, p = .016, ω² = .04) and the presence of a comorbidity (F = 51.21, p \u3c .001, ω² = .27) were significant explanatory variables for total Brief-BESTest scores in youth with VIs. These results suggested that youth with VIs are likely to have impaired balance performance in both static and dynamic tasks (i.e., five out of six balance systems) when compared to peers without VIs. Balance impairments in youth with VIs are likely due to environmental and/or sociological constraints and can likely be improved with targeted intervention. Practitioners should acknowledge and consider the roles of vision level and/or the presence of a comorbidity when investigating multidimensional balance performance in youth with VIs. The purpose of Study 3 was to investigate associations between Brief-BESTest and the Test of Gross Motor Development-3 (TGMD-3) locomotor subscale scores in youth with VIs. Ninety-six youth with VIs (nboys = 52) aged 8.7 to 19.0 years (M = 12.98± 2.28) completed the Brief-BESTest and the TGMD-3 locomotor subscale. The zero- order Spearman correlation between Brief-BESTest and TGMD-3 locomotor subscale total scores was strong (ρ = .60, p \u3c .001, 95% CI = .46 to .72). Vision level and the presence of a comorbidity were identified as confounding variables. A second-order partial Spearman correlation simultaneously controlling for the presence of a comorbidity and vision level was .42 (p \u3c .001, 95% CI = .24 to .57).These data suggest that a significant monotonic association existed between global multidimensional balance and locomotor performance in youth with VIs (i.e., total scores). Concerning individual Brief- BESTest and TGMD-3 item relationships, results were mixed. Zero-order Spearman correlations between individual Brief-BESTest and TGMD-3 locomotor subscale items ranged from -.09 to .55. It could be suggested that certain balance systems may play a role in (e.g., constrain) certain locomotor skills in youth with VIs. Practitioners should acknowledge that specific balance systems may play a more prominent or withdrawn role in different locomotor skills (i.e., inter-task specificity). Thus, practitioners should actively develop multidimensional balance skills in youth with VIs in tandem with other motor skills. These data have the potential to significantly impact balance assessment which could in turn influence (adapted) physical education curricula (e.g., Individualized Education Program goals) or therapeutic/rehabilitative decisions for youth with VIs. Information gleaned from this dissertation suggests that multidimensional balance could be posited as a significant (yet modifiable) mechanism of action which could be constraining health- and movement-based outcomes in youth with VIs

The effect of beetroot juice supplementation dose on neuromuscular performance during resistance exercise

Dietary nitrate supplementation, administered as beetroot juice (BR), enhances powerful and fast contractions; however, whether BR impacts resistance exercise performance and if dosing influences the efficacy of nitrate are underdeveloped. The purpose of this study is to assess whether BR supplementation influences neuromuscular performance (muscle power and speed), in healthy, recreationally active males. In a double-blind, randomized crossover design, 15 males will be randomly allocated to consume 4 x 70 ml of BR over four conditions: (1) 4 x 70 ml of nitrate-depleted BR for placebo (PL); (2) 1 x 70 ml of nitrate-rich BR and 3 x 70 ml of PL for a low nitrate dose (BR-LOW); (3) 2 x 70 ml of nitrate-rich BR and 2 x 70 ml of PL for a moderate nitrate dose (BR-MOD); and (4) 4 x 70 ml of nitrate-rich BR for an elevated nitrate dose (BR-HIGH). Participants will report to the laboratory 5 times over 5-wk. Participants will complete a 1 repetition max (1RM) and a familiarization to the exercise protocol. On experimental visits, participants will complete a warm up and then a protocol to assess explosive performance using a linear transducer and force plate during vertical countermovement jumps, and then back squat and bench press, in a randomized order. A resting blood sample will be drawn for the determination of plasma nitrate and nitrite concentrations. These data could provide insight for dietary nitrate as an ergogenic aid and inform both supplementation guidelines and recommendations for enhancing resistance training performance in men

Pomegranate extract supplementation on neuromuscular performance during resistance exercise

Dietary nitrate supplementation has been shown to improve skeletal muscle function during high-velocity and high-power contractions due to its high nitrate levels; however, there is limited data examining its potential in exercise requiring these movements, such as resistance exercise. Nitrate supplementation has been studied extensively as beetroot juice, but its poor taste severely limits its application. Pomegranate extract (POM) may be an alternative nitrate source due to its superior taste, high nitrate content, and additional antioxidants but has yet to be explored. The purpose of the present study is two-fold: 1) to determine the nitrate concentration in POM; and 2) to examine the effect of POM supplementation on neuromuscular performance during resistance exercise. In phase 1, the concentration of nitrate in commercially available pomegranate products was quantified to guide dosing regimens for phase 2. During Phase 2, in a double-blind, randomized, crossover design, 15 healthy recreationally active males and females will arrive to the laboratory for 5 visits over 3-4 weeks. Participants will perform a one repetition maximum test followed by a familiarization to the protocol. Following this, participants will perform 3 experimental conditions by consuming: 1) empty capsules containing negligible nitrate (PL); 2) a conventional dose of nitrate (POM-NORM, 9 mmol of nitrate); and 3) a high dose of nitrate (POM-HIGH, 13.5 mmol of nitrate) ~2.5 hours prior to exercise testing. During experimental visits, a resting blood draw will be obtained, then subjects will perform a protocol for determining power during countermovement jumps, kneeling countermovement pushups, and back squats. Muscle power will be determined by using a force plate and linear transducer. Results for Phase 1 of the study showed that POM extract contained 2.2 mmol of nitrate per gram of the 200 mg/mL extract. Therefore, it is recommended that participants ingest 6 capsules for 9 mmol of nitrate or 9 capsules for 13.5 mmol of nitrate. Phase 2 is in the data collection phase and ongoing

The effect of a single dose of beetroot juice on speed, strength, and power in healthy recreationally active females.

Nitrate-rich beetroot juice (BR) improves muscle contraction which is relevant for intense intermittent-type sports. However, few studies have examined the effect of BR ingestion on performance using sport-specific exercise protocols. Moreover, there is a scarcity of research that include female participants which limits real world application given that females potentially have different responses to BR ingestion. The purpose of the present study was to examine the effect of BR supplementation on speed, acceleration, strength and power before and after fatigue in females. In a double-blind, randomized crossover design, 15 recreationally active females consumed BR and nitrate-depleted placebo juice (PL) ~2.5 hours prior to exercise testing. Measurements included 20 m sprint and acceleration using timing gates, strength using isokinetic handgrip dynamometry, and upper and lower body power using the medicine ball power throw and countermovement jump (CMJ) before and after a fatiguing running protocol. Data from a subset of participants (n=15) were analyzed and revealed no significant difference between PL and BR for 20 m speed and 10 m acceleration (P\u3e0.05), isokinetic handgrip dynamometry (PL: PRE: 76±10 vs POST: 76±13; BR: PRE: 78±12 vs POST: 78±12 lb; P\u3e0.05), medicine ball power throw (PL: PRE: 4.45±0.48 vs POST: 4.35±0.48; BR: PRE: 4.41±0.38 vs POST: 4.49±0.47 m; P\u3e0.05) or CMJ (PL: PRE: 1.72±0.27 vs POST: 1.7±0.26; BR: PRE: 1.77±0.25 vs POST: 1.73±0.28 m; P\u3e0.05). These results indicate that there are no effects of BR supplementation on exercise performance in female athletes; however, this study is currently underpowered, and research is still in progress

The effects of nitrate-rich beetroot juice supplementation on nonverbal executive function in healthy recreationally active females

Nitrate-rich beetroot juice (BR) supplementation has been reported to preserve executive function (i.e. decision making and reaction time) before and after a simulated soccer match in recreationally active males, which may be due to enhanced cerebral blood flow. However, the literature examining the physiological response following BR ingestion in females is scarce, which hampers the extrapolation of results since physiological sex-differences may exist. Therefore, the purpose of this study was to assess if BR ingestion influenced executive function in an unfatigued and fatigued state in healthy recreationally active females. In a double-blind, randomized crossover design, 20 females consumed 140 mL of concentrated BR or nitrate-depleted placebo juice (PL) approximately 2.5 hours prior to each experimental visit. The Delis-Kaplan Executive Function (D-KEF) test, used for assessing higher-level cognitive function, was administered before and after completing a high-intensity intermittent running protocol. The D-KEF test involved 3 x 60-s conditions evaluating various cognitive tasks. A two-way repeated measures analysis of variance was conducted (n=15) and revealed no significant differences in executive function between PL (PRE: 15.27 ± 32.71 vs. POST: 16.93 ± 1.44) and BR (PRE: 15.80 ± 2.65 vs. POST: 16.60 ± 1.88). These preliminary data suggest that acute BR ingestion does not have an influence on processing and creative thinking of nonverbal executive function in an unfatigued or fatigued state in healthy recreationally active females, although importantly, the study is still in progress

The Effects of Acute Beetroot Juice Ingestion on Exercise and Cognitive Performance in Female Athletes

Nitrate-rich beetroot juice can enhance intense exercise performance which is attributed to enhanced skeletal muscle contractility. However, limited data exist in females and it is unknown whether dietary nitrate has an ergogenic effect in this population. PURPOSE: To investigate the potential effects of acute nitrate ingestion on a battery of exercise performance and cognitive tests before and after fatiguing intermittent running exercise. METHODS: Fifteen female team-sport athletes were assigned in a randomized, double-blind, crossover design to consume nitrate-rich beetroot juice (BR; 12 mmol of nitrate) and nitrate-depleted beetroot juice (PL; 0.10 mmol of nitrate) 2.5 h prior to performing the exercise protocol, with a washout period of 7 days between trials. Running 10 m and 20 m sprint split times, sprint reaction time, upper- and lower-body power, handgrip strength, and cognitive flexibility were measured before and after the Yo-Yo intermittent recovery level 1 (Yo-Yo IR1) test, during which performance and rate of perceived exertion were recorded. RESULTS: There were no significant differences in any performance outcome or cognitive flexibility (P \u3e 0.05). CONCLUSION: These findings indicate that acute nitrate ingestion does not influence performance in sprints, intermittent running, power, strength, or cognitive function in young adult female team-sport athletes

The effects of acute beetroot juice ingestion on upper and lower body muscular power during weightlifting exercise in men

Nitrate-rich beetroot juice (BR) supplementation improves movements with high-velocity and high-power muscle contractions which may be due to enhanced blood flow, oxygenation and contractile function in type II muscle fibers. The literature has focused predominantly on the effects of BR supplementation running and cycling performance, but its efficacy in resistance exercise, a modality that relies on type II muscle fibers, has limited data. Furthermore, it is unknown how supplementation strategies impact the physiological and ergogenic effects of BR during exercise. Therefore, the purpose of this study is to assess whether single or multi-day nitrate ingestion will improve performance and muscle oxygenation during resistance exercise. In a double-blind, randomized crossover design, 14 healthy recreationally active men will report to the laboratory for five occasions over a 4-wk period. On the first visit, participants will undergo a 1 repetition-max (1RM) test for back squat and bench press. Subsequently, participants will complete two 4-day experimental trials where they will consume 2 x 70mL doses per day of either nitrate-depleted placebo (PL) or concentrated nitrate-rich BR. On experimental days of each supplementation period (day 1 and 4), subjects will consume 140 mL of their allocated beverage 2.5-h before exercise. On day 2 and 3 of the supplementation period, participants will consume one 70 mL beverage in the morning and one in the evening. On experimental days, participants performed a power protocol, consisting of 2 sets x 2 repetitions of back squats and bench press at 70%1RM followed by repetition-to-failures at 60%1RM. Muscle oxygenation, power and velocity were assessed during exercise using near infrared spectroscopy and a linear transducer, respectively. A subset of data has been collected (n=9) and data collection is ongoing

The effects of acute beetroot juice ingestion on upper and lower body muscular power during weightlifting exercise in men.

Dietary nitrate supplementation, administered per beetroot juice (BR), has been shown to enhance performance while cycling and running. BR has enhanced skeletal muscle contraction and blood flow within type II fibers which are recruited during high-velocity and high-power contractions. However, it is unknown whether BR influences alternative forms of exercise, such as resistance exercise. The purpose of this study is to assess whether BR supplementation influences neuromuscular performance (muscle power and speed), and repetitions-to-failure in healthy, recreationally active men. In a double-blind, randomized crossover design, 14 males will be recruited to complete two 4-day supplementation periods in which they consume 2 x 70mL nitrate-depleted placebo (PL) or nitrate-rich BR per day. Subjects will report to the lab 5 times over a 3-to 4-wk period. Subjects will complete a 1 repetition max (1RM) test and familiarization to the protocol. On experimental days subjects will complete a warm up and then a protocol to assess explosive performance, consisting of 2 sets x 2 repetitions of back squat at 70% 1RM using a cadence that emphasizes an explosive concentric phase. Skeletal muscle oxygenation will be measured using near-infrared spectroscopy and neuromuscular performance will be measured during exercise using a linear transducer. Following a 5-min recovery period, subjects performed 1 set x repetition-to-failure at 60% 1RM to determine muscular endurance. This protocol will be repeated in the bench press exercise. Data was analyzed in a subset of n = 9. There were no significant differences in resistance exercise performance between conditions; however, data collection is ongoing and results are currently underpowered. These data could provide insight for dietary nitrate as an ergogenic aid and inform both supplementation guidelines and recommendations for enhancing resistance training performance in men

Impact of KRAS mutation status on the efficacy of immunotherapy in lung cancer brain metastases

Immune checkpoint inhibitors (ICIs) have resulted in improved outcomes in non-small cell lung cancer (NSCLC) patients. However, data demonstrating the efficacy of ICIs in NSCLC brain metastases (NSCLCBM) is limited. We analyzed overall survival (OS) in patients with NSCLCBM treated with ICIs within 90 days of NSCLCBM diagnosis (ICI-90) and compared them to patients who never received ICIs (no-ICI). We reviewed 800 patients with LCBM who were diagnosed between 2010 and 2019 at a major tertiary care institution, 97% of whom received stereotactic radiosurgery (SRS) for local treatment of BM. OS from BM was compared between the ICI-90 and no-ICI groups using the Log-Rank test and Cox proportional-hazards model. Additionally, the impact of KRAS mutational status on the efficacy of ICI was investigated. After accounting for known prognostic factors, ICI-90 in addition to SRS led to significantly improved OS compared to no-ICI (12.5 months vs 9.1, p \u3c 0.001). In the 109 patients who had both a known PD-L1 expression and KRAS status, 80.4% of patients with KRAS mutation had PD-L1 expression vs 61.9% in wild-type KRAS patients (p = 0.04). In patients without a KRAS mutation, there was no difference in OS between the ICI-90 vs no-ICI cohort with a one-year survival of 60.2% vs 54.8% (p = 0.84). However, in patients with a KRAS mutation, ICI-90 led to a one-year survival of 60.4% vs 34.1% (p = 0.004). Patients with NSCLCBM who received ICI-90 had improved OS compared to no-ICI patients. Additionally, this benefit appears to be observed primarily in patients with KRAS mutations that may drive the overall benefit, which should be taken into account in the development of future trials

Effects of Dietary Nitrate Supplementation on Performance and Muscle Oxygenation during Resistance Exercise in Men

The purpose of the current study was to assess the effects of acute and short-term nitrate (NO3−)-rich beetroot juice (BR) supplementation on performance outcomes and muscle oxygenation during bench press and back squat exercise. Fourteen recreationally active males were assigned in a randomized, double-blind, crossover design to supplement for 4 days in two conditions: (1) NO3−-depleted beetroot juice (PL; 0.10 mmol NO3− per day) and (2) BR (11.8 mmol NO3− per day). On days 1 and 4 of the supplementation periods, participants completed 2 sets of 2 × 70%1RM interspersed by 2 min of recovery, followed by one set of repetitions-to-failure (RTF) at 60%1RM for the determination of muscular power, velocity, and endurance. Quadriceps and pectoralis major tissue saturation index (TSI) were measured throughout exercise. Plasma [NO3−] and nitrite ([NO2−]) were higher after 1 and 4 days of supplementation with BR compared to PL (p \u3c 0.05). Quadriceps and pectoralis major TSI were not different between conditions (p \u3e 0.05). The number of RTF in bench press was 5% greater after acute BR ingestion compared to PL (PL: 23 ± 4 vs. BR: 24 ± 5, p \u3c 0.05). There were no differences between BR and PL for RTF for back squat or power and velocity for back squat or bench press (p \u3e 0.05). These data improve understanding on the ergogenic potential of BR supplementation during resistance exercise