No effect of fluid intake on neutrophil responses to prolonged cycling

Ingesting carbohydrate beverages during prolonged exercise is associated with fewer numbers of circulating neutrophils and attenuated neutrophil functional responses, yet there is little information about the effect of fluid intake alone on immune responses to prolonged exercise. The aim of this study was to examine the influence of regular fluid ingestion compared with no fluid ingestion on plasma cortisol, circulating neutrophil and lipopolysaccharide (LPS)-stimulated neutrophil degranulation responses to prolonged cycling. In a randomized design, nine recreationally active males cycled for 2 h at 65% VO2max on two occasions with either fluid ingestion (lemon-flavoured water, fluid trial) before and during the exercise, or with no fluid intake at all (no fluid trial). Venous blood samples were obtained at rest, immediately after exercise and 1 h after exercise. Immediately after exercise, the plasma cortisol concentration was significantly higher in the no fluid trial than in the fluid trial (592 +/- 62 vs 670 +/- 63 nmol x l(-1), P < 0.05). Circulating numbers of neutrophils increased 4.5-fold (P < 0.01) and LPS-stimulated elastase release per neutrophil decreased 34 +/- 7% (P < 0.01) immediately after exercise; there were no differences between trials. These results suggest that in ambient environmental conditions, fluid ingestion alone has a negligible effect on circulating neutrophil and LPS-stimulated neutrophil degranulation responses to prolonged exercise.     

The effects of carbohydrate supplementation on immune responses to a soccer-specific exercise protocol

The aim of this study was to determine the effect of carbohydrate (CHO) versus placebo (PLA) beverage consumption on the immune and plasma cortisol responses to a soccer-specific exercise protocol in 8 university team soccer players. In a randomized, counterbalanced design, the players received carbohydrate or placebo beverages before, during and after two 90 min soccer-specific exercise bouts (3 days apart) designed to mimic the activities performed and the distance covered in a typical soccer match. Blood and saliva samples were collected before, during and after the exercise protocol. Plasma lactate concentration increased to approximately 4 mmol x l(-1) at 45 and 90 min of exercise in both treatments (P<0.01). Plasma glucose concentration was significantly lower after 90 min of exercise with ingestion of the placebo than the carbohydrate (PLA: 4.57+/-0.12 mmol x l(-1); CHO: 5.49+/-0.11 mmol x l(-1); P<0.01). The pattern of change in plasma cortisol, circulating lymphocyte count and saliva immunoglobulin A secretion did not differ between the carbohydrate and placebo trials. Blood neutrophil counts were 14% higher 1 h after the placebo trial than the carbohydrate trial (PLA: 4.8+/-0.5x10(9) cells x l(-1); CHO: 4.2+/-0.5x10(9) cells x l(-1); P = 0.06), but the treatment had no effect on the degranulation response of blood neutrophils stimulated by bacterial lipopolysaccharide. We conclude that, although previous studies have shown that carbohydrate feeding is effective in attenuating immune responses to prolonged continuous strenuous exercise, the same cannot be said for a soccer-specific intermittent exercise protocol. When overall exercise intensity is moderate, and changes in plasma glucose, cortisol and immune variables are relatively small, it would appear that carbohydrate ingestion has only a minimal influence on the immune response to exercise.     

The menstrual cycle and its effect on the immune status of female endurance runners

Twenty highly trained, eumenorrhoeic female endurance runners were studied over three consecutive menstrual cycles. Average training distance per week, total years training and mood states were recorded throughout the three cycles. Salivary progesterone and menstrual cycle diaries were recorded over the first two cycles to identify luteal phase onset and the presence of any menstrual irregularities. Saliva samples were collected daily over the third cycle for analysis of immunoglobulin A (IgA) concentration and secretion and saliva flow rate. Two-way analysis of variance (ANOVA) revealed no significant differences in mood states across the phases of the menstrual cycle (P > 0.05). Training logs indicated that training did not alter throughout the 3 month study. One-way ANOVA revealed no significant differences in IgA concentration (P = 0.92), secretion rate (P = 0.84) or saliva flow rate (P = 0.95) across the phases of the menstrual cycle. Pearson's product-moment correlation revealed no relationship between IgA concentration and progesterone between the phases of the cycle (r = 0.39). We conclude that, in ovulatory female endurance runners whose physical and emotional stress are stable, IgA concentration is not significantly affected by fluctuations in progesterone during the menstrual cycle.     

The Ordering Challenge: An Online Game to Introduce Independent Demand Inventory Concepts

Students are put in the role of a manager who watches inventory levels decrease and must order at the right time and in the right quantity to minimize costs. This interactive game requires the students to race against time and has levels of increasing difficulty. It introduces the students to the concepts of holding cost, ordering cost, backlog cost, the sawtooth curve, reorder point, order quantity, ABC categorization, and continuous review systems. The game is simple and is available free online. An accompanying assignment is designed to guide the student's reflection process while playing the game.     

Bang for the Buck: Autonomy and Charter School Efficiency in Milwaukee

Charter schools are a relatively new phenomenon in American education. Since the first charter school opened in Minnesota in 1991, they have expanded to 42 states and represent 6.2% of all public schools in the country.¹ This growth has been attributed to a number of factors, chief among them evidence that charter schools can improve performance (Lamdin and Mintrom, 1997). While there is a substantial evidence for relative performance benefits of charter schooling (e.g. CREDO, 2015) far less research been conducted on the efficiency of charter schools relative to traditional public schools. What research there is has produced both positive (e.g. Wolf et. al., 2014) and negative results (e.g. Carpenter and Noller, 2010). What can account for the disparity in these findings? In this paper, I make the case that differences in charter efficiency may be accounted for by differences in their level of autonomy from the school district. I base this argument on economic theories that the devolution of power to the lowest level possible tends to produce gains in efficiency (Johnson, 1991; Duncombe and Yinger, 1997). Those that are “on the ground” are thought to be more effective at monitoring expenditures, and allocations of resources have to pass through less ‘red tape (Hess 2006).’ In addition, more autonomous charter schools better fit the original purpose of charter schools in devolving power from centralized authorities (Budde, 1996). In order to test this theory, I take advantage of a unique situation that exists in Milwaukee, Wisconsin in which three types of charter schools with varying levels of autonomy operate simultaneously. Using school type as a proxy for autonomy, I find that more independent charter schools are more efficient than traditional public schools and charter schools with less autonomy.