Safety and efficacy of a probiotic cocktail containing P. acidilactici and L. plantarum for gastrointestinal discomfort in endurance runners: randomized double-blinded crossover clinical trial.

Probiotics are increasingly used to treat conditions associated with gastrointestinal injury and permeability, including exercise-induced gastrointestinal discomfort. This study assessed safety and efficacy of a probiotic in altering the intestinal milieu and mitigating gastrointestinal symptoms (GIS) in endurance runners. In a double blind, crossover study, 16 runners were randomized to 4 weeks of daily supplementation with a probiotic cocktail containing Pediococcus acidilactici bacteria and Lactobacillus plantarum or placebo. Fasting blood and stool samples were collected for measurement of gut permeability markers, immune parameters, and microbiome analyses. Treadmill run tests were performed before and after treatment; participants ran at 65%-70% of VO2max at 27 °C for a maximum of 90 min or until fatigue/GIS developed. A blood sample was collected after the treadmill run test. In healthy individuals, 4 weeks of probiotic supplementation did not alter health parameters, although a marginal reduction in aspartate aminotransferase levels was observed with probiotic treatment only (p = 0.05). GIS, gut permeability-associated parameters (intestinal fatty acid binding protein, lipopolysaccharide binding protein, zonulin, and cytokines), and intestinal microbial content were not altered by the probiotic supplementation. Post-run measurements of GIS and gut-associated parameters did not differ between groups; however, the observed lack of differences is confounded by an absence of measurable functional outcome as GIS was not sufficiently induced during the run. Under the current study conditions, the probiotic was safe to use, and did not affect gut- or immune-associated parameters, or intestinal symptoms in a healthy population. The probiotic might reduce tissue damage, but more studies are warranted.

Age-related kinematic changes in late visual-cueing during obstacle circumvention.

On a daily basis, we are challenged by common environmental obstacles (e.g. street posts) that require simple and often rapid modifications to our gait patterns to avoid collisions. Poor vision appears to be responsible for important reductions in postural stability during gait; and therefore, individuals with impaired vision, such as the elderly, may be at a greater risk of falling, especially under conditions where stepping avoidance strategies may be constrained by the environment. The purpose of the current study was to examine the body segment and eye-gaze reorientation strategy, role of base of support, as well as visual areas of interest attended to by healthy young (YA) and older adults (OA) when only given limited time, one stride, to prepare for an obstacle circumvention task. Six YA and six OA were asked to perform ten walking trials which required them to circumvent an obstacle in their travel path. Participants used one of two avoidance strategies, either lead leg crossing-over trail leg (narrow base of support) or lead leg stepping-out (wide base of support). Results indicate that base of support constraints did not affect segment reorientation sequence in either age group. The general segment reorientation sequence in YA was initiated by trunk yaw and head yaw, followed by gaze and finally, by M-L foot deviation. No trunk roll deviations were observed. In OA, the general segment reorientation sequence was the following: trunk yaw and trunk roll, gaze and finally, M-L foot deviation. No head yaw deviations were observed. Our findings suggest that YA utilized a foot placement strategy to perform the transient change in travel direction while OA relied on a hip strategy. In addition, YA spent more time gazing straight ahead at the obstacle and the wall, while OA spent more time looking at the ground. This strategy indicates that OA use a more cautious strategy to safely avoid the obstacle. Findings from the present work contribute further knowledge regarding locomotor adjustments during a common, and complex, everyday task in young and older adults.

Age-related modifications in steering behaviour: effects of base-of-support constraints at the turn point.

This study investigated the effects of altering the base of support (BOS) at the turn point on anticipatory locomotor adjustments during voluntary changes in travel direction in healthy young and older adults. Participants were required to walk at their preferred pace along a 3-m straight travel path and continue to walk straight ahead or turn 40 degrees to the left or right for an additional 2-m. The starting foot and occasionally the gait starting point were adjusted so that participants had to execute the turn using a cross-over step with a narrow BOS or a lead-out step with a wide BOS. Spatial and temporal gait variables, magnitudes of angular segmental movement, and timing and sequencing of body segment reorientation were similar despite executing the turn with a narrow or wide BOS. A narrow BOS during turning generated an increased step width in the step prior to the turn for both young and older adults. Age-related changes when turning included reduced step velocity and step length for older compared to young adults. Age-related changes in the timing and sequencing of body segment reorientation prior to the turn point were also observed. A reduction in walking speed and an increase in step width just prior to the turn, combined with a delay in motion of the center of mass suggests that older adults used a more cautious combined foot placement and hip strategy to execute changes in travel direction compared to young adults. The results of this study provide insight into mobility constraints during a common locomotor task in older adults.