Browsing by Author "Fling, Brett, advisor"

Now showing 1 - 3 of 3

Embargo
Countermeasures to metabolic impairment during circadian misalignment
(Colorado State University. Libraries, 2024) Lowry, Catherine, author; Broussard, Josiane, advisor; Fling, Brett, advisor; DuBose, Lydnsey, committee member; Johnson, Sarah, committee member
People who work evening, night or rotating shifts (i.e. "nonstandard" work hours) represent one in five U.S. employees and are at a 44% increased risk for developing Type 2 diabetes (T2D) compared to people who work standard day shifts. Shift workers experience acute, repeated bouts of misalignment between their endogenous circadian system and external behavior/environmental factors such as sleep, energy intake, activity, and light. Circadian misalignment is one mechanism suggested to increases the risk of T2D in shift-working populations. To date, there have been limited attempts at identifying strategies or countermeasures to prevent the impact of such circadian misalignment on T2D risk in a sizeable proportion of the population. The following thesis aims to test a nutritional countermeasure known as time-restricted eating (TRE). TRE has previously shown metabolic benefits in people with obesity. The overall aims of the two studies compiled within this thesis are to determine the impact of TRE on (1) circulating and muscle lipid accumulation and (2) insulin sensitivity and glycemic homeostasis. Both studies follow a randomized crossover design with a rigorous inpatient diet-, activity and light-controlled protocol in 32 healthy men and women. In these studies, participants underwent a 6d randomized crossover inpatient study with at least 1 month between conditions. In one condition, participants ate during the biological night as typically done during night shift work (circadian misalignment). In the other condition, participants consumed meals only in the biological daytime (circadian misalignment + time restricted eating), while keeping sleep times and diet consistent. Consolidating food intake to the biological daytime, particularly in night shift work, was hypothesized to reduce the risk of T2D by reducing the mismatch between the endogenous circadian system and external behaviors. Findings from this study represent a critical advancement in the fields of translational circadian and metabolic physiology by identifying and testing a countermeasure to circadian misalignment. Achievement of our proposed aims could lead to the development of new intervention strategies for chronic disease prevention and management. The knowledge to be gained offers the potential to support cost-effective programs that may inform our healthcare approach to metabolic disease prevention in populations at risk for these diseases such as shift workers, individuals with sleep disorders and anyone who eats outside of daytime hours.
Open Access
Movement for mobility: associations between physical activity, postural control, and gait in people with multiple sclerosis
(Colorado State University. Libraries, 2021) Bandera, Victoria Maria, author; Fling, Brett, advisor; Leach, Heather, advisor; Diehl, Manfred, committee member
Background: Approximately 80% of people with multiple sclerosis (PwMS) experience impaired balance and mobility. The optimal duration, type and intensity of physical activity (PA) to improve balance and gait is not well understood. Purpose: Examine associations between PA duration, type and intensity with balance and gait in PwMS and neurotypical controls. Methods: Twenty-four PwMS and twenty-one neurotypical controls reported their typical PA routine, including duration [(days/week)x(minutes/bout)], type (aerobic, resistance and/or plyometric (R/P) and yoga), and intensity (rating of perceived exertion (RPE) 6-20). Balance was assessed by the mini Balance Evaluation Systems Test (Mini-BESTest). Gait speed was measured by the two-minute walk test at a normal pace and a fast pace. Pearson's and Spearman's correlations examined associations among PA variables, balance, and gait speed. Independent t-tests and Mann-Whitney U tests examined differences in gait speeds and balance, between participants who did vs. did not perform each PA type. MANOVA and Kruskal-Wallis tests compared gait and balance performance in participants who reported ≥150 PA minutes/week, and vigorous PA (RPE > 14) vs. those who did not. Results: No significant associations were found between PA duration and any outcomes in either group. Conversely, PA intensity was significantly associated with reactive postural control, rs(24) = .458, p < .05, sensory orientation, rs (24) = .487, p < .05, and dynamic gait, rs(24) = .429, p < .05, and anticipatory postural control in neurotypical controls, rs(21) = .476, p < .05. As for PA type, self-reported habitual R/P was associated with nearly significantly superior dynamic gait performance in PwMS, p = .07, but significantly lower normal gait speed in neurotypical controls, p < .05. Participants who met and/or exceeded the 150-minute per week PA guideline did not have differences in any outcomes. Habitually vigorous PA was associated with significantly improved anticipatory postural control, H(1) = 5.86, p < .05, and nearly significantly improved Mini-BEST scores in neurotypical participants H(1) = 3.273, p = 0.07. Minimally clinically important differences in fast gait speed (> 0.10 m/s) were found in neurotypical participants habitually performing vigorous PA compared to light-to-moderate PA. Conclusions: These findings suggest PA intensity and participation in R/P and yoga are associated with better balance and gait performance. Future studies should reevaluate these associations incorporating PA intensity measured by self-report perceived intensity and objectively measured, and incorporating R/P training into PA routines to improve balance and gait outcomes in PwMS.
Open Access
The transcallosal highway: the ipsilateral silent period as a neural biomarker for impaired corpus callosum communication and gait asymmetry in people with multiple sclerosis
(Colorado State University. Libraries, 2023) Acosta, Jordan, author; Fling, Brett, advisor; Rudolph, Alan, committee member; Miravalle, Augusto, committee member; Schmid, Arlene, committee member
Multiple sclerosis is a neurodegenerative disease that damages the myelin sheath within the central nervous system. Axonal demyelination, particularly in the corpus callosum, impacts communication between the brain's hemispheres in persons with multiple sclerosis (PwMS). Changes in transcallosal communication impairs the coordination of gait which requires constant communication across the corpus callosum to excite and inhibit specific muscle groups. To further evaluate the functional role of transcallosal communication in gait and mobility, this study assessed the ipsilateral silent period (iSP), an indirect marker of transcallosal inhibition in PwMS. This study utilizes transcranial magnetic stimulation (TMS) to assess the inhibitory capacity between the brain's hemispheres. There is a lack of research analyzing directionality data between the more and less affected hemisphere in PwMS. Therefore, we evaluated outcome metrics dependent upon the individual's more affected hemisphere calculated from the subject's more affected limb observed during walking assessments and self-report. We hypothesize that the iSP may serve as a neural biomarker for transcallosal impairments evaluated by directionality differences between the hemispheres and highlight transcallosal inhibition as an underlying neural mechanism for gait asymmetries in PwMS. From twenty-nine PwMS, metrics such as depth iSP% average, duration, depth iSP% max, and onset latency were collected. No statistically significant differences were found between the two hemispheres. This suggests that PwMS may be able to preserve their interhemispheric inhibitory capacity irrespective of their more affected hemisphere. Additionally, another component of the study investigated gait coordination utilizing a split-belt treadmill training paradigm. Limb excursion asymmetry (LEA) measures, pre and post-training, were analyzed for spatial coordination and as a measurement of locomotor adaptability in PwMS. The relationship between LEA change and dSP% average highlighted a significant correlation (r=0.46, p= 0.02). Thus, showing that less interhemispheric inhibition corresponds with more spatial adaptability leading to a more symmetric gait. These findings may help determine the potential of iSPs as a neural biomarker to address gait asymmetries and stratify participants into mobility rehabilitation protocols.