Search Results

You are looking at 41 - 50 of 174 items for :

  • "buffering" x
Clear All
Restricted access

Charles J. Hardy, Jack M. Richman and Lawrence B. Rosenfeld

This study examined the role of social support in the relationship between life stress and injury. Utilizing a prospective design, male and female collegiate athletes participating in the sports of volleyball, gymnastics, field hockey, soccer, cross-country, track and field, and wrestling completed the Athletic Life Experience Survey and the Support Functions Questionnaire. The results indicated that life stress and social support were predictive of injury frequency among male athletes. Specifically, injury frequency increased as the level of total life change and the number of providers of shared social reality support increased (direct effect). In addition, injury frequency was found to increase as negative life change and the number of providers of, and degree of fulfillment for, emotional challenge support decreased (buffer effect). No significant models emerged for female athletes or injury severity. The results of this study support a functional or disaggregated role for social support in the life stress/injury relationship.

Restricted access

Lynn Van den Berghe, Greet Cardon, Nathalie Aelterman, Isabel Barbara Tallir, Maarten Vansteenkiste and Leen Haerens

Burnout in teachers is related to different maladaptive outcomes. This study aimed at exploring the relationship between emotional exhaustion and motivation to teach in 93 physical education teachers. Results showed that teachers report more emotional exhaustion when they are less autonomously motivated, while the opposite relationship was found for controlled motivation. Next, four motivational profiles were identified by means of cluster analyses: (a) a relative controlled group, (b) a relative lowly motivated group, (c) a relative autonomous group, and (d) a relative highly motivated group. The controlled group reported most emotional exhaustion, whereas the relative autonomous and highly motivated group had the lowest scores on emotional exhaustion. The results indicate that being autonomously motivated may function as a “buffer” against the development of emotional exhaustion. This implicates that it is important for politicians, directors, teachers, and teacher educators to consider teachers’ type of motivation to teach to prevent emotional exhaustion.

Restricted access

Vincent J. Dalbo, Michael D. Roberts, Scott E. Hassell, Jordan R. Moon and Chad M. Kerksick

Background:

This investigation examined the safety and efficacy of a silica-based mineral antioxidant complex (MAC) that has been suggested to influence body water and buffer lactate.

Methods:

In a double-blind, randomized crossover design, male participants completed testing for 3 conditions: water only (baseline), rice flour (placebo), and MAC supplementation. Participants visited the laboratory on 5 occasions: familiarization, baseline, Testing Day 1, washout, and Testing Day 2. Baseline and Testing Days 1 and 2 consisted of fasting blood, pre- to postexercise body-water assessment and determination of VO2peak on a cycle ergometer. The supplementation protocols were separated by 1 wk and balanced to minimize an order effect.

Results:

No differences between conditions were found for heart rate, blood pressure, or serum-safety markers (p > .05). Before exercise there were no differences between conditions for total body water (TBW), intracellular water (ICW), or extracellular water (ECW). No significant interactive effects for supplementation and exercise were found for TBW, ICW, or ECW (p > .05). A time effect for TBW (p < .01) and ICW (p < .001) was present. Within-group changes in TBW occurred in the MAC condition, and within-group changes for ICW occurred in the MAC and placebo conditions. Ratings of perceived exertion and blood lactate increased (p < .05) with exercise. No significant effects were found for performance variables.

Conclusions:

MAC supplementation had no impact on aerobic exercise performance and lactate response. Increases in TBW and ICW occurred after MAC consumption, but these changes appeared to have minimal physiological impact.

Restricted access

Dieter Böning

In modern societies there is strong belief in scientific progress, but, unfortunately, a parallel partial regress occurs because of often avoidable mistakes. Mistakes are mainly forgetting, erroneous theories, errors in experiments and manuscripts, prejudice, selected publication of “positive” results, and fraud. An example of forgetting is that methods introduced decades ago are used without knowing the underlying theories: Basic articles are no longer read or cited. This omission may cause incorrect interpretation of results. For instance, false use of actual base excess instead of standard base excess for calculation of the number of hydrogen ions leaving the muscles raised the idea that an unknown fixed acid is produced in addition to lactic acid during exercise. An erroneous theory led to the conclusion that lactate is not the anion of a strong acid but a buffer. Mistakes occur after incorrect application of a method, after exclusion of unwelcome values, during evaluation of measurements by false calculations, or during preparation of manuscripts. Co-authors, as well as reviewers, do not always carefully read papers before publication. Peer reviewers might be biased against a hypothesis or an author. A general problem is selected publication of positive results. An example of fraud in sports medicine is the presence of doped subjects in groups of investigated athletes. To reduce regress, it is important that investigators search both original and recent articles on a topic and conscientiously examine the data. All co-authors and reviewers should read the text thoroughly and inspect all tables and figures in a manuscript.

Restricted access

Wim Derave and Kevin D. Tipton

Many athletes use dietary supplements, with use more prevalent among those competing at the highest level. Supplements are often self-prescribed, and their use is likely to be based on an inadequate understanding of the issues at stake. Supplementation with essential micronutrients may be useful when a diagnosed deficiency cannot be promptly and effectively corrected with food-based dietary solutions. When used in high doses, some supplements may do more harm than good: Iron supplementation, for example, is potentially harmful. There is good evidence from laboratory studies and some evidence from field studies to support health or performance benefits from appropriate use of a few supplements. The available evidence from studies of aquatic sports is small and is often contradictory. Evidence from elite performers is almost entirely absent, but some athletes may benefit from informed use of creatine, caffeine, and buffering agents. Poor quality assurance in some parts of the dietary supplements industry raises concerns about the safety of some products. Some do not contain the active ingredients listed on the label, and some contain toxic substances, including prescription drugs, that can cause health problems. Some supplements contain compounds that will cause an athlete to fail a doping test. Supplement quality assurance programs can reduce, but not entirely eliminate, this risk.

Restricted access

Gulshanara Begum, Adam Cunliffe and Michael Leveritt

High-intensity exercise leads to reductions in muscle substrates (ATP, PCr, and glycogen) and a subsequent accumulation of metabolites (ADP, Pi, H+, and Mg2+) with a possible increase in free radical production. These factors independently and collectively have deleterious effects on muscle, with significant repercussions on high-intensity performance or training sessions. The effect of carnosine on overcoming muscle fatigue appears to be related to its ability to buffer the increased H+ concentration following high-intensity work. Carnosine, however, has other roles such as an antioxidant, a metal chelator, a Ca2+ and enzyme regulator, an inhibitor of protein glycosylation and protein-protein cross-linking. To date, only 1 study has investigated the effects of carnosine supplementation (not in pure form) on exercise performance in human subjects and found no improvement in repetitive high-intensity work. Much data has come from in vitro work on animal skeletal muscle fibers or other components of muscle contractile mechanisms. Thus further research needs to be carried out on humans to provide additional understanding on the effects of carnosine in vivo.

Restricted access

Philip J. Troped, Heather A. Starnes, Robin C. Puett, Kosuke Tamura, Ellen K. Cromley, Peter James, Eran Ben-Joseph, Steven J. Melly and Francine Laden

There are few studies of built environment associations with physical activity and weight status among older women in large geographic areas that use individual residential buffers to define environmental exposures. Among 23,434 women (70.0 ± 6.9 yr; range = 57–85) in 3 states, relationships between objective built environment variables and meeting physical activity recommendations via walking and weight status were examined. Differences in associations by population density and state were explored in stratified models. Population density (odds ratio [OR] =1.04 [1.02, 1.07]), intersection density (ORs = 1.18–1.28), and facility density (ORs = 1.01–1.53) were positively associated with walking. Density of physical activity facilities was inversely associated with overweight/obesity (OR = 0.69 [0.49, 0.96]). The strongest associations between facility density variables and both outcomes were found among women from higher population density areas. There was no clear pattern of differences in associations across states. Among older women, relationships between accessible facilities and walking may be most important in more densely populated settings.

Restricted access

Genevieve Fridlund Dunton, Donna Spruijt-Metz, Jennifer Wolch, Chih-Ping Chou, Michael Jerrett, Jason Byrne, Susan Weaver and Kim D. Reynolds

Background:

Efforts to increase community levels of physical activity through the development of multiuse urban trails could be strengthened by information about factors predicting trail use. This study examined whether reasons for trail use predict levels of physical activity on urban trails.

Methods:

Adults (N = 335) living within a 1-mile buffer zone of urban trails in Chicago, Dallas, and Los Angeles completed a self-report measure assessing demographics, reason for trail use, and physical activity on the trail. Accelerometers measured total daily moderate-to-vigorous physical activity (MVPA). Environmental features of the urban trail were assessed with the Systematic Pedestrian and Cyclist Environmental Scan for trails measure. Multivariate regression analyses were conducted that accounted for clustering of individuals within trail segments.

Results:

After controlling for demographic and environmental factors and total daily MVPA, reasons for trail use significantly predicted recreational but not transportation activity. Recreational trail activity was greater for participants who reported exercise and health reasons for trail use as compared with other reasons (ie, social interaction, enjoying nature, walking pets) for recreational trail use.

Conclusions:

To increase the use of urban trails, it may be useful to promote the health and exercise benefits of recreational trail use.

Restricted access

Damien Clement and Vanessa R. Shannon

Context:

According to the buffering hypothesis, social support moderates the harmful effects of stress and, in turn, indirectly affects injured athletes’ health and well-being. Previous research suggests that perceptions of social support influence athletes’ psychological reactions, as well as their rehabilitation adherence, but additional research in this area is warranted.

Objective:

To examine injured athletes’ perceptions regarding satisfaction, availability, and contribution for each of the 8 types of social support.

Design:

Descriptive.

Setting:

Mid-Atlantic Division II and III institutions.

Participants:

49 injured athletes.

Main Outcome Measures:

Social support was assessed using a modified version of the Social Support Survey.

Results:

Injured athletes were significantly more satisfied with social support provided by athletic trainers (ATCs) than that provided by coaches and teammates. In addition, injured athletes reported that social support provided by ATCs contributed significantly more to their overall well-being. Athletes reported several significant differences regarding satisfaction and contribution to well-being among the 8 different types of social support.

Conclusions:

Injury, an unavoidable part of sport, is often accompanied by negative psychological reactions. This reaction may have a negative influence on an athlete’s experience of injury and rehabilitation. Findings suggest that perceptions of social support provided by ATCs have the greatest influence on injured athletes’ rehabilitation and well-being.

Restricted access

Zhongren Sun, Xiaoning Li, Zhiqiang Su, Ying Zhao, Li Zhang and Mingyuan Wu

Context:

Bone marrow stromal cells (BMSCs) can be differentiated into neuronal cells and are used to treat spinal cord injury (SCI).

Objective:

This study investigated whether electroacupuncture enhances BMSC’s effects on SCI in rats.

Design:

The effects of transplantation of phosphate-buffered saline or BMSC, electroacupuncture, and a combination of BMSC transplantation and electroacupuncture on SCI were evaluated using a combined behavioral score (CBS). Expressions of neuronal marker neuron-specific enolase (NSE) and gliocyte-specific marker glial fibrillary acidic protein (GFAP) of transplanted BMSC were detected using immunohistochemistry to assess the effect of electroacupuncture on differentiation of BMSC into neuronal cells.

Results:

The combination of BMSC transplantation and electroacupuncture significantly alleviated CBS in rats with SCI compared with the separate treatment of BMSC or electroacupuncture. In addition, electroacupuncture increased the NSE- and GFAP-positive transplanted BMSCs in spinal cord.

Conclusion:

Combined treatment showed a better effect, and the mechanisms may be partially caused by enhanced differentiation of BMSC into neuronal cells. Future studies are needed to confirm this.