The Relationship between Cardiac Load and Metabolic Changes throughout a Collegiate Cross-country Season

Overtraining is a widespread epidemic in collegiate cross-cross country which causes excessive fatigue and limits improvement in critical physiological measures such as maximal oxygen uptake (VO2 max), ventilatory threshold (VT), and running economy (RE). Research has suggested that overtraining can be identified by monitoring daily and weekly cardiac load (CL) as well as changes in load over time measured by an acute to chronic cardio load ratio (A:C). Assessing the relationships between these foundational aerobic athlete variables and A:C will provide important information about fitness changes over the course of a competitive season as well as potential insight into the overtraining phenomenon. PURPOSE: To determine the metabolic changes in elite endurance athletes over a cross country season and identify a relationship with cardio load and A:C. METHODS: Volunteer participants ranging from 18-23 years of age were recruited from the Illinois State University cross country team for this study. Athletes recorded heart rate data daily from each training session and attended both a pre and post season laboratory testing session. In the lab, a discontinuous maximal graded exercise test was performed consisting of 3 submaximal bouts lasting 4 minutes each separated by 1 minute of rest. After the 3rd stage and subsequent rest, a maximal ramp protocol was initiated by increasing the incline 1% each minute until volitional exhaustion. An analysis of the metabolic variables of interest was conducted in Microsoft Excel to determine change from pre to posttest as well as any interactions with cardiac load data. RESULTS: A:C tended to decrease throughout the season for most athletes with the team average gradually declining from 1.11 during the week of September 25th to 0.65 for October 30th. Top performers at the postseason championship races had the highest average A:Cs (Top male: 1.30; Top female 0.95), and worst performers for a given race tended to have the lowest relative CL in the preceding week. In the lab, there was high individual variability and few significant global changes. Average VO2 max for males increased from 66.3 mL.kg-1.min-1 during preseason testing to 67.3 mL.kg-1.min-1 for postseason (53.8 to 53.8 for females). Individual outlying VO2 max values tended to regress towards the mean, VT increased slightly for both sexes (Females: +5.1 %VO2; Males: +4.6 %VO2 max) with established long-distance runners consistently demonstrating the highest values, and RE improved moderately for all stages excluding 2 notable outliers. Top performers according to test duration typically had the best RE values for all stages (Female: 42.4, 79.3 & 86.7 %VO2 max for stages 1,2 & 3; Male: 66.1, 72.1, 83.5 %VO2 max). CONCLUSION: Data suggests that maintaining consistently high CL and A:Cs above 0.9 throughout the season may be optimal for improving race performance. Specifically, CL should not decrease significantly in the week leading up to a competition. Physiological testing confirms the importance of measuring VO2 max, VT, and RE, and monitoring changes in these values over the year could be predictive of performance or potential success at specific distances.KEYWORDS: Cardio Load, Internal Workload, VO2 max, Ventilatory Threshold, Running Economy, Endurance Running, Distance Runnin

Bulletin No. 383 - Cooperative Nutritional Status Studies in the Western Region: I. Nutrient Intake

In 1947, a concerted study of the nutritional status of selected population groups was initiated in the western region of the United States. Previous dietary surveys had indicated that substantial portions of the country\u27s population were consuming lower than recommended levels of essential nutrients. Deficiency diseases that may have nutritional background, such as dental caries, anemia, and rickets, existed. Investigators reported subclinical signs of malnutrition in several areas. Few studies had been made in the West, although reports of high incidence of dental caries and suspected undernutrition had come from several western states. The regional committee thought it evident that the presence of endemic nutritional deficiencies, imbalances, and excesses should be investigated within the western region, and their causes in environmental factors or food habits should be studied. Such conditions might be widespread and cross state lines. Hence the regional approach was appropriate

Stop the beat to see the rhythm: excitation-contraction uncoupling in cardiac research.

Optical mapping is an imaging technique that is extensively used in cardiovascular research, wherein parameter-sensitive fluorescent indicators are used to study the electrophysiology and excitation-contraction coupling of cardiac tissues. Despite many benefits of optical mapping, eliminating motion artifacts within the optical signals is a major challenge, as myocardial contraction interferes with the faithful acquisition of action potentials and intracellular calcium transients. As such, excitation-contraction uncoupling agents are frequently used to reduce signal distortion by suppressing contraction. When compared with other uncoupling agents, blebbistatin is the most frequently used, as it offers increased potency with minimal direct effects on cardiac electrophysiology. Nevertheless, blebbistatin may exert secondary effects on electrical activity, metabolism, and coronary flow, and the incorrect administration of blebbistatin to cardiac tissue can prove detrimental, resulting in erroneous interpretation of optical mapping results. In this “Getting It Right” perspective, we briefly review the literature regarding the use of blebbistatin in cardiac optical mapping experiments, highlight potential secondary effects of blebbistatin on cardiac electrical activity and metabolic demand, and conclude with the consensus of the authors on best practices for effectively using blebbistatin in optical mapping studies of cardiac tissue

SALIVARY ANTIMICROBIAL PROTEIN RESPONSE TO PROLONGED RUNNING

Prolonged exercise may compromise immunity through a reduction of salivary antimicrobial proteins (AMPs). Salivary IgA (IgA) has been extensively studied, but little is known about the effect of acute, prolonged exercise on AMPs including lysozyme (Lys) and lactoferrin (Lac). Objective: To determine the effect of a 50-km trail race on salivary cortisol (Cort), IgA, Lys, and Lac. Methods: 14 subjects: (6 females, 8 males) completed a 50km ultramarathon. Saliva was collected pre, immediately after (post) and 1.5 hrs post race ( 1.5). Results: Lac concentration was higher at 1.5 hrs post race compared to post exercise (p<0.05). Lys was unaffected by the race (p>0.05). IgA concentration, secretion rate, and IgA/Osm were lower 1.5 hrs post compared to pre race (p<0.05). Cort concentration was higher at post compared to 1.5 (p<0.05), but was unaltered from pre race levels. Subjects finished in 7.81 ± 1.2 hrs. Saliva flow rate did not differ between time points. Saliva Osm increased at post (p<0.05) compared to pre race. Conclusions: The intensity could have been too low to alter Lys and Lac secretion rates and thus, may not be as sensitive as IgA to changes in response to prolonged running. Results expand our understanding of the mucosal immune system and may have implications for predicting illness after prolonged running

The Lived Experiences of Students and Faculty of a Christian College who Participated in a Short-term International Mission Trip

Short-term international mission trips (STIMTs) are increasing in popularity. Likewise, educators and health care workers are increasingly concerned with obtaining an understanding that improves culturally competent care. The purpose of this study was to investigate the lived experiences of participants of a Christian college who travelled on a short-term international mission trip (STIMT). One openended inquiry guided the interviews: How would you describe your experience as a participant who travelled on a STIMT? An in-depth, oneon- one interview of participants occurred until data saturation was reached. Colaizzi’s strategy was used to analyze and organize the data. Leininger’s sunrise model was used to guide this study. Themes that emerged from this study included cultural adaptation, relationships, spiritual factors, and personal gain

Relationships Effecting College Students’ Perception of Family Influence Impacting their Health and Lifestyle

The purpose of this cross-sectional, nonexperimental descriptive design study was to determine college students’ perception of family influence impacting their health and lifestyle. The sample included 120 college students in a faithbased institution and each student completed a Likert-type survey (4-point agreement scale) that investigated their perception of health, and the degree of influence peers and family had on their health. This second data analysis reports correlations between variables and group differences related to health perceptions and behaviours. The strongest correlation is between ‘family demonstration of positive health habits’ and ‘personal health practices being like my families’ (r = 0.671, p \u3c 0.01), a moderate relationship supported by other weaker positive correlations to specific health outcomes. Negative correlations between ‘my friends display more positive health habits than family’ and both ‘family has influenced my idea of health’ and ‘my health practices are similar to my family’ indicate the potential for other contextual factors to effect family impact. While differences relating to health influence and outcomes between groups formed by age, gender, ethnicity, family structure and religion were found, the variable related to most healthy lifestyle transmission elements was ‘My family demonstrates positive health habits’. Recommendations supporting improved societal health are offered, together with suggestions for further research. Group classifications that are fixed but might inform interactions with elements of cohorts are identified, together with group memberships which might be changed to enhance health options. Caution in the generalisation of these findings is advised due to the explained limitations of this study

Evaluation of a medical self-care program in a hospital setting.

Medical self-care programs have captured the attention of health promotion professionals, especially within worksite settings. The basic premise of medical self-care is that if employees or clients can be taught to make responsible and informed decisions about medical problems, they will use the health care delivery system more wisely. Numerous researchers (Kemper, 1982; Vickery 1983, Roberts, 1983 and Long 1985) have highlighted both the effectiveness and cost-effectiveness of medical self-care programs. The purpose of this "Research Brief" is to discuss the impact of a structured medical self-care program implemented in a hospital worksite

Bisphenol A exposure and cardiac electrical conduction in excised rat hearts

BACKGROUND: Bisphenol A (BPA) is used to produce polycarbonate plastics and epoxy resins that are widely used in everyday products, such as food and beverage containers, toys and medical devices. Human biomonitoring studies have suggested that a large proportion of the population may be exposed to BPA. Recent epidemiological studies have reported correlations between increased BPA urinary concentrations and cardiovascular disease; yet the direct effects of BPA on the heart are unknown. OBJECTIVES: The goal of our studies was to measure BPA\u27s effect (0.1-100 μM) on cardiac impulse propagation ex vivo, using excised whole hearts from adult rats. METHODS: We measured atrial and ventricular activation times during sinus and paced rhythms using epicardial electrodes and optical mapping of transmembrane potential. Atrioventricular activation intervals and epicardial conduction velocities were computed using recorded activation times. RESULTS: Cardiac BPA exposure resulted in prolonged PR segment and decreased epicardial conduction velocity (0.1 - 100 μM), prolonged action potential duration (1 - 100 μM) and delayed atrioventricular conduction (10 - 100 μM). Importantly, these effects were observed after acute exposure (≤ 15 min), underscoring the potential detrimental effects of continuous BPA exposure. The highest BPA concentration used (100 μM) resulted in prolonged QRS intervals, dropped ventricular beats and eventually resulted in complete heart block. CONCLUSIONS: Our results show that acute BPA exposure slows electrical conduction in excised hearts from female rats. These findings emphasize the importance of examining BPA\u27s effect on heart electrophysiology and determining whether chronic in vivo exposure can cause/exacerbate conduction abnormalities in patients with pre-existing heart conditions and other high-risk populations