Christopher M. Bopp

Relationship between brachial artery blood flow and total [hemoglobin + myoglobin] during post-occlusive reactive hyperemia

The associations between macrovascular and microvascular responses reported previously during post-occlusive reactive hyperemia have been inconsistent. The purpose of this study was therefore to determine the temporal relationship between the reactive hyperemic responses within a conduit artery and the downstream microvessels. Conduit artery blood flow was measured in the brachial artery with pulsed Doppler ultrasound. A potential analog of microvascular flow, changes in skeletal muscle total[hemoglobin+myoglobin] (T[Hb+Mb]), was assessed with near-infrared spectroscopy (NIRS). We found a high degree of correlation between these two measures (r=0.91). Cross-correlation analysis revealed two distinct response patterns. In 10 of our 15 subjects there was time displacement between peak brachial artery blood flow (BABF) and T[Hb+Mb] responses; in the remaining 5 the peaks were coincident. Granger causality testing suggested that reactive hyperemia in the macrovessel determined hyperemia in the downstream microvessels in all 15 study subjects. Time constants for the on (τ1) and off (τ2) kinetics of each response were calculated; our initial hypothesis was that τ1 and τ2 for T[Hb+Mb] would correlate with τ1 and τ2 for BABF, respectively. However, only for τ2 was this observed (r=0.52; p<0.05). No similar relationship was observed for τ1. Adipose tissue thickness did not influence either time constant for T[Hb+Mb]. Taken together, our results show that the temporal characteristics of the hyperemic response in the conduit artery are qualitatively reflected in the downstream microvasculature, but mechanisms for quantitative differences remain to be identified.

Active Transportation to and on Campus is Associated With Objectively Measured Fitness Outcomes Among College Students

BACKGROUND Active transportation (AT) has been associated with positive health outcomes, yet limited research has addressed this with college students, a population at-risk for inactivity. The purpose of this study was to examine the relationship between AT behavior and objectively measured fitness outcomes. METHODS A volunteer, convenience sample (n = 299) of college students from a large northeastern university completed a survey about their AT habits to and on campus and psychosocial constructs related to AT and participated in a laboratory-based fitness assessment (cardiovascular endurance, muscular strength and endurance, flexibility, body composition).Off-campus students were dichotomized as nonactive (0-1 AT trips/day) or active travelers (> 1 AT trips/day) to campus; t-tests compared nonactive and active travelers for psychosocial and fitness variables. RESULTS Students were 56.3% male, 79.2% non-Hispanic White, and primarily living off-campus (87%). Most students (n = 177, 59.2%) reported active travel between classes. Off-campus students were primarily active travelers (76.1%). Active travelers to campus had greater cardiovascular fitness (P = .005), were more flexible (P = .006) and had lower systolic blood pressure (P = .05) compared with nonactive travelers. CONCLUSION This study documents a relationship between AT behavior and objectively measured fitness among college students and provides a rationale for targeting this behavior as a method for improving health outcomes.

Implementation and evaluation of an Exercise is Medicine™ on campus week

UNLABELLED Exercise is Medicine™ (EiM) on campus targets physical activity (PA) participation on college campuses. Limited research has addressed how PA initiatives can be operationalized on college campuses. PURPOSE To describe the implementation of EiM on a large U.S. university campus and present preliminary outcomes on participation and awareness. METHODS EiM week was implemented on a large university campus. Exercise stations were set-up at campus locations to encourage brief bouts of PA and educate about the benefits of PA. Evaluation included observations of participation, surveys, and intercept surveys to assess awareness and reach. RESULTS EiM week was implemented during Fall 2013. Exercise stations elicited 1771 exercise bouts from participants. Surveys indicated widespread reach across the university (13 of 17 colleges); most students (50.8%) became aware of the EiM campaign by passing by the exercise stations. Campus intercept surveys 1-week post-event indicated 54% students had heard about EiM, of which 39% had heard/seen the event through messages encouraging exercise. CONCLUSION The current study was successful in engaging a large, diverse population on a college campus. Lessons learned from the development, implementation, and evaluation of EiM on campus activities provide insight for university campuses looking to target student health and PA participation.