Comparison of Household Perceptions and Practices of Food and Water Emergency Preparedness Between Latter-Day Saints and Non-Latter-Day Saints in the USA.

This study evaluated whether Latter-day Saints have more favorable perceptions and practices of food and water emergency preparedness than other households. Individuals across 46 states in the USA completed an online survey in 2014 (n = 572). Results indicated that Latter-day Saints, compared to Non-Latter-day Saints, were more likely to have a disaster supplies kit, to have long-term food storage, to have preserved food by canning/bottling, and to perceive neighborhood/community connectedness. Latter-day Saints had significantly lower odds of having less than one month of food storage available compared to Non-Latter-day Saints. Our findings suggest Latter-day Saints may be better prepared to handle a disaster than Non-Latter-day Saints.

Effects of added absorption on the vocal exertions of talkers in a reverberant room.

Occupational speech users such as schoolteachers develop voice disorders at higher rates than the general population. Previous research has suggested that room acoustics may influence these trends. The research reported in this paper utilized varying acoustical conditions in a reverberant room to assess the effects on vocal parameters of healthy talkers. Thirty-two participants were recorded while completing a battery of speech tasks under eight room conditions. Vocal parameters were derived from the recordings and the statistically significant effects of room acoustics were verified using mixed-model analysis of variance tests. Changes in reverberation time (T20), early decay time (EDT), clarity index (C50), speech transmission index (STI), and room gain (GRG) all showed highly correlated effects on certain vocal parameters, including speaking level standard deviation, speaking rate, and the acoustic vocal quality index. As T20, EDT, and GRG increased, and as C50 and STI decreased, vocal parameters showed tendencies toward dysphonic phonation. Empirically derived equations are proposed that describe the relationships between select room-acoustic parameters and vocal parameters. This study provides an increased understanding of the impact of room acoustics on voice production, which could assist acousticians in improving room designs to help mitigate unhealthy vocal exertion and, by extension, voice problems.

Multifidus Muscle Size and Symmetry in Ballroom Dancers with and without Low Back Pain.

The incidence of low back pain (LBP) among elite ballroom dancers is high and understanding associations between muscle morphology and pain may provide insight into treatment or training options. Research has linked multifidus muscle atrophy to LBP in the general and some athletic populations; however, this has not been examined in ballroom dancers. We compared the lumbar multifidus cross-sectional area (CSA) at rest in 57 elite level ballroom dancers (age 23±2.4 years; height, 174±11 cm; mass, 64±10 kg) divided into one of three pain groups, according to their self-reported symptoms, 1) LBP group (n=19), 2) minimal LBP (n=17), and 3) no LBP (n=21). There were no significant difference in demographics between the groups (P>0.05). The LBP group demonstrated significant differences in reported pain and Oswestry Disability Index scores compared to the other two groups. There was no significant difference between groups in multifidus cross-sectional area (P=0.49). Asymmetry was found in all groups with the overall left side being significantly larger than the right (P<0.002). Pain associated with segmental decrease in multifidus CSA was not observed in ballroom dancers with LBP, suggesting other reasons for persistent LBP in ballroom dancers.

Bergamot (Citrus bergamia) Essential Oil Inhalation Improves Positive Feelings in the Waiting Room of a Mental Health Treatment Center: A Pilot Study.

Mental health issues have been increasingly recognized as public health problems globally. Their burden is projected to increase over the next several decades. Additional therapies for mental problems are in urgent need worldwide due to the limitations and costs of existing healthcare approaches. Essential oil aromatherapy can provide a cost-effective and safe treatment for many mental problems. This pilot study observed the effects of bergamot essential oil inhalation on mental health and well-being, as measured by the Positive and Negative Affect Scale, in a mental-health treatment center located in Utah, USA. Fifty-seven eligible participants (50 women, age range: 23-70 years) were included for analysis. Fifteen minutes of bergamot essential oil exposure improved participants' positive feelings compared with the control group (17% higher). Unexpectedly, more participants participated in experimental periods rather than control periods, suggesting even brief exposure to essential oil aroma may make people more willing to enroll in clinical trials. This study provides preliminary evidence of the efficacy and safety of bergamot essential oil inhalation on mental well-being in a mental health treatment center, suggesting that bergamot essential oil aromatherapy can be an effective adjunct treatment to improve individuals' mental health and well-being. © 2017 The Authors. Phytotherapy Research published by John Wiley & Sons Ltd.

Psychometrically equivalent bisyllabic words for speech recognition threshold testing in Vietnamese.

OBJECTIVE: This study identified, digitally recorded, edited and evaluated 89 bisyllabic Vietnamese words with the goal of identifying homogeneous words that could be used to measure the speech recognition threshold (SRT) in native talkers of Vietnamese. DESIGN: Native male and female talker productions of 89 Vietnamese bisyllabic words were recorded, edited and then presented at intensities ranging from -10 to 20 dBHL. Logistic regression was used to identify the best words for measuring the SRT. Forty-eight words were selected and digitally edited to have 50% intelligibility at a level equal to the mean pure-tone average (PTA) for normally hearing participants (5.2 dBHL). STUDY SAMPLE: Twenty normally hearing native Vietnamese participants listened to and repeated bisyllabic Vietnamese words at intensities ranging from -10 to 20 dBHL. RESULTS: A total of 48 male and female talker recordings of bisyllabic words with steep psychometric functions (>9.0%/dB) were chosen for the final bisyllabic SRT list. Only words homogeneous with respect to threshold audibility with steep psychometric function slopes were chosen for the final list. CONCLUSIONS: Digital recordings of bisyllabic Vietnamese words are now available for use in measuring the SRT for patients whose native language is Vietnamese.

Investigation of a recent rise of dual amantadine-resistance mutations in the influenza A M2 sequence.

BACKGROUND: The S31N amantadine-resistance mutation in the influenza A M2 sequence currently occurs more frequently in nature than the S31 wild type. Overcoming the resistance of the S31N mutation is the primary focus of M2 researchers who aim to develop novel antiviral therapies. Recent studies have noted a possible rise in frequency of the V27A/S31N double amantadine-resistance mutation in recent years. The purpose of this study is to investigate this recent rise in frequency of the double mutation and any possible bias of the other mutations toward co-occurrence with S31N or S31 strains. RESULTS: The primary dataset used for this study was comprised of 24,152 influenza A M2 channel sequences which were downloaded from UniProt. There is an increased frequency for the S31N/V27A dual AR mutation in recent years, especially in swine. A test for difference in two proportions indicates that the V27A mutation is co-occurring with S31N more often than expected (p-value<0.001) when considering individual amino acid frequencies. At the same time, the different propensities for the V27A as compared to the V27T dual mutant may reflect differences in viral fitness or protein energetics, and this information could be exploited to focus drug development so as to reduce further drug insensitivity. CONCLUSIONS: The development of the S31N/V27A variant in the Midwestern US swine may be a harbinger of novel human strain development. V27A/S31N is a possible path forward for the evolution of M2 which may convey a new level of drug resistance and should receive attention in drug design.

Microbial and chemical safety of non-commercially packaged water stored for emergency use.

Water storage is one of the most important components of emergency preparedness. Potable water is needed for ensuring the survival and well-being of disaster victims. Consumers may store water in previously used beverage or other food-grade containers for emergency use; however, this practice poses potential safety risks. Water stored in various containers for emergency purposes in residences within the state of Utah was tested for various contaminants. Of 240 samples, seven contained coliforms and 14 samples had free chlorine levels over the Environmental Protection Agency (EPA) 4 parts per million limit. There was a negative correlation between chlorine levels and age of water. The probability that a container had free chlorine present decreased by 4% for each month of storage, suggesting the importance of preventing subsequent contamination of water during storage and use. Water in clear polyethylene terephthalate plastic soda bottles (n=16), even when stored for >18 months, did not exceed 0.3 parts per billion (ppb) antimony, a level significantly lower than the EPA limit of 6.0 ppb antimony. These results support the practice of utilizing previously used containers, when properly cleaned and chlorinated, for emergency water storage.

Comparison of Single-Point and Continuous Sampling Methods for Estimating Residential Indoor Temperature and Humidity.

Residential temperature and humidity are associated with multiple health effects. Studies commonly use single-point measures to estimate indoor temperature and humidity exposures, but there is little evidence to support this sampling strategy. This study evaluated the relationship between single-point and continuous monitoring of air temperature, apparent temperature, relative humidity, and absolute humidity over four exposure intervals (5-min, 30-min, 24-hr, and 12-days) in 9 northern Utah homes, from March-June 2012. Three homes were sampled twice, for a total of 12 observation periods. Continuous data-logged sampling was conducted in homes for 2-3 wks, and simultaneous single-point measures (n = 114) were collected using handheld thermo-hygrometers. Time-centered single-point measures were moderately correlated with short-term (30-min) data logger mean air temperature (r = 0.76, ß = 0.74), apparent temperature (r = 0.79, ß = 0.79), relative humidity (r = 0.70, ß = 0.63), and absolute humidity (r = 0.80, ß = 0.80). Data logger 12-day means were also moderately correlated with single-point air temperature (r = 0.64, ß = 0.43) and apparent temperature (r = 0.64, ß = 0.44), but were weakly correlated with single-point relative humidity (r = 0.53, ß = 0.35) and absolute humidity (r = 0.52, ß = 0.39). Of the single-point RH measures, 59 (51.8%) deviated more than ±5%, 21 (18.4%) deviated more than ±10%, and 6 (5.3%) deviated more than ±15% from data logger 12-day means. Where continuous indoor monitoring is not feasible, single-point sampling strategies should include multiple measures collected at prescribed time points based on local conditions.

The influence of risk perception on biosafety level-2 laboratory workers' hand-to-face contact behaviors.

Pathogen transmission in the laboratory is thought to occur primarily through inhalation of infectious aerosols or by direct contact with mucous membranes on the face. While significant research has focused on controlling inhalation exposures, little has been written about hand contamination and subsequent hand-to-face contact (HFC) transmission. HFC may present a significant risk to workers in biosafety level-2 (BSL-2) laboratories where there is typically no barrier between the workers' hands and face. The purpose of this study was to measure the frequency and location of HFC among BSL-2 workers, and to identify psychosocial factors that influence the behavior. Research workers (N = 93) from 21 BSL-2 laboratories consented to participate in the study. Two study personnel measured workers' HFC behaviors by direct observation during activities related to cell culture maintenance, cell infection, virus harvesting, reagent and media preparation, and tissue processing. Following observations, a survey measuring 11 psychosocial predictors of HFC was administered to participants. Study personnel recorded 396 touches to the face over the course of the study (mean = 2.6 HFCs/hr). Of the 93 subjects, 67 (72%) touched their face at least once, ranging from 0.2-16.0 HFCs/hr. Among those who touched their face, contact with the nose was most common (44.9%), followed by contact with the forehead (36.9%), cheek/chin (12.5%), mouth (4.0%), and eye (1.7%). HFC rates were significantly different across laboratories F(20, 72) = 1.85, p = 0.03. Perceived severity of infection predicted lower rates of HFC (p = 0.03). For every one-point increase in the severity scale, workers had 0.41 fewer HFCs/hr (r = -.27, P < 0.05). This study suggests HFC is common among BSL-2 laboratory workers, but largely overlooked as a major route of exposure. Workers' risk perceptions had a modest impact on their HFC behaviors, but other factors not considered in this study, including social modeling and work intensity, may play a stronger role in predicting the behavior. Mucous membrane protection should be considered as part of the BSL-2 PPE ensemble to prevent HFC.

Sensor drift and predicted calibration intervals of handheld temperature and relative humidity meters under residential field-use conditions.

Handheld temperature and relative humidity (T/RH) meters are commonly used in residential indoor air surveys. Although popular, T/RH meters are prone to sensor drift and consequent loss of accuracy, and thus instrument manufacturers often recommend annual calibration and adjustment. Field-use conditions, however, have been shown to accelerate electronic sensor drift in outdoor applications, resulting in out-of-tolerance measurements in less than one year. In the study described in this article, sensor drift was evaluated under residential field use for 30 handheld T/RH meters to predict needed calibration intervals based on hierarchical linear modeling. Instruments were used in 43 home visits over a 93-day period and were calibrated (without adjustment) 49 times over the study period with a laboratory standard. Analysis of covariance showed significant drift among temperature sensors for all three instrument types (p < .0001) and among humidity sensors in two instruments. The authors' study suggests calibration frequency should be based on instrument performance under specific sampling conditions rather than on predetermined time intervals.

Investigation of Precepting-related Burnout in Dietetics Preceptors.

BACKGROUND: Dietetics preceptors are at risk for abandoning the role of dietetic preceptor because of potential burnout. Identifying factors associated with greater and lesser burnout can help key stakeholders identify and implement strategies that prevent or mitigate burnout in dietetics preceptors. OBJECTIVE: The purpose of this study was to identify factors associated with the burnout preceptors attribute specifically to the work of precepting. DESIGN: This study used a cross-sectional study design. A survey instrument including burnout measures, precepting measures, and items querying personal and work characteristics was distributed via email to a random sample of 10,000 credentialed dietetics professionals. PARTICIPANTS/SETTING: Respondents who lived in the United States, were currently practicing, and had precepted during the past year were included in the sample (n=310). The survey was conducted in October and November of 2022. MAIN OUTCOME MEASURES: Precepting-related burnout was measured using scores on the Copenhagen Burnout Inventory, in which scores range from 0-100, with higher numbers indicating greater burnout. STATISTICAL ANALYSES PERFORMED: Factors associated with precepting-related burnout were identified using an analysis of covariance. Pairwise comparisons with Tukey adjustments were done to determine differences across categories for the categorical variable in the model (percent of interns requiring additional coaching). A step-wise variable selection process was performed to determine the best analytic models. RESULTS: Factors associated with lower precepting-related burnout in dietetics preceptors include higher Commitment to the Preceptor Role (CPR) scores, lower percentages of interns requiring additional coaching, feeling appreciated by the dietetic intern, and higher Preceptors' Perceptions of Support (PPS) scores. A factor associated with higher precepting-related burnout was precepting a greater number of dietetic interns in the past year. For every one-point change in each variable, the degree of change in precepting-related burnout was -7.9 for CPR, -3.2 for feeling appreciated by interns, -4.5 for PPS, and +1.2 for number of interns per year. The average difference in precepting-related burnout scores between preceptors who reported <10% interns requiring additional coaching and those who reported >50% interns requiring additional coaching was-13.7 (3.7). CONCLUSIONS: The factors found to be associated with precepting-related burnout scores in dietetics preceptors are potentially modifiable, suggesting this burnout might be prevented or mitigated to some degree.

Combination effects of dietary soy and methylselenocysteine in a mouse model of prostate cancer.

BACKGROUND: High dietary intake of soy or selenium (Se) is associated with decreased risk of prostate cancer. Soy constituents and various chemical forms of Se have each been shown to downregulate expression of the androgen receptor (AR) and AR-regulated genes in the prostate. We hypothesized that downregulation of AR and AR-regulated genes by the combination of these dietary components would inhibit tumorigenesis in the TRansgenic Adenocarcinoma of Mouse Prostate (TRAMP) mouse. METHODS: Male mice were exposed from conception to stock diets high or low in soy, with or without a supplement of Se-methylseleno-L-cysteine (MSC) in a 2 × 2 factorial design. Mice were sacrificed at 18 weeks. Prostate histopathology, urogenital tract (UGT) weight, hepatic activity of androgen-metabolizing enzymes, and expression of AR, AR-regulated, and AR-associated FOX family genes, in the dorsolateral prostate were examined. RESULTS: High soy intake decreased activity of hepatic aromatase and 5α-reductase, expression of AR, AR-regulated genes, FOXA1, UGT weight, and tumor progression, and upregulated protective FOXO3. Supplemental MSC upregulated AKR1C14, which reduces 5α-dihydrotestosterone. CONCLUSIONS: Soy is an effective pleiotropic dietary agent for prevention of prostate cancer. The finding of effects of soy on FOX family gene expression in animals is novel. Combination effects of supplemental MSC may depend upon the soy content of the basal diet to which it is added.

Consumption of blueberries with a high-carbohydrate, low-fat breakfast decreases postprandial serum markers of oxidation.

We sought to determine whether consumption of blueberries could reduce postprandial oxidation when consumed with a typical high-carbohydrate, low-fat breakfast. Participants (n 14) received each of the three treatments over 3 weeks in a cross-over design. Treatments consisted of a high blueberry dose (75 g), a low blueberry dose (35 g) and a control (ascorbic acid and sugar content matching that of the high blueberry dose). Serum oxygen radical absorbance capacity (ORAC), serum lipoprotein oxidation (LO) and serum ascorbate, urate and glucose were measured at fasting, and at 1, 2 and 3 h after sample consumption. The mean serum ORAC was significantly higher in the 75 g group than in the control group during the first 2 h postprandially, while serum LO lag time showed a significant trend over the 3 h for both blueberry doses. Changes in serum ascorbate, urate and glucose were not significantly different among the groups. To our knowledge, this is the first report that has demonstrated that increased serum antioxidant capacity is not attributable to the fructose or ascorbate content of blueberries. In summary, a practically consumable quantity of blueberries (75 g) can provide statistically significant oxidative protection in vivo after a high-carbohydrate, low-fat breakfast. Though not tested directly, it is likely that the effects are due to phenolic compounds, either directly or indirectly, as they are a major family of compounds in blueberries with potential bioactive activity.

Effect of high-speed treadmill training with a body weight support system in a sport acceleration program with female soccer players.

Maximum running speed and acceleration are essential components in many sports. The identification of specific training protocols to maximize sprint speed would be useful knowledge for coaches and players. The purpose of this study was to determine the effect of a high-speed treadmill (HST) with the use of a body weight support (BWS) system in a 6-week sport acceleration program (SAP) on female soccer athlete's 40-yard sprint time and maximal isometric knee flexor and extensor strength. Two treatment groups and one control group were created. Both treatment groups participated in a 12-session SAP. The first treatment group (n = 12) used a BWS system while running on a HST; the second group (n = 12) used a standard treadmill (ST) with no BWS system. The participants of the control group (n = 8), NT, did not participate in a sports acceleration program and did not alter their exercise routines outside of the study. An analysis of covariance was performed using baseline measures as the covariate. The 40-yard sprint times for both treatment groups were shown to improve significantly compared with the control group (p < 0.001). Isometric knee flexor strength showed a greater increase in the ST group (p = 0.026) than in the other 2 groups, whereas knee extensor strengths did not show significant differences between treatment groups and control group (p > 0.05). Participants in the ST group had a much higher rate (66%) of shin splints and foot pain throughout the study than those in the HST (8%) and NT (0%) groups. These results can help high school coaches and athletes determine the optimal treadmill training regime.

Modeling of the chest wall response to prolonged bracing in pectus carinatum.

Pectus carinatum is a chest wall deformity that is often treated through the wearing of an external brace. The treatment of the deformity could benefit from a greater understanding of chest wall characteristics under prolonged loading. These characteristics are difficult to model directly but empirical studies can be used to create statistical models. 185 patients from 2018-2020 received bracing treatment. Data on the severity of the deformity, treatment pressures, and time of wear were recorded at the first fitting and all subsequent follow-up visits. This data was analyzed using a statistical mixed effects model to identify significant measures and trends in treatment. These models were designed to help quantify changes in chest wall characteristics through prolonged bracing. Two statistical models were created. The first model predicts the change in the amount of pressure to correct the deformity after bracing for a given time and pressure. The second model predicts the change in pressure response by the body on the brace after bracing for a given time and pressure. These models show a high significance in the amount of pressure and time to the changes in the chest wall response. Initial deformity severity is also significant in changes to the deformity. The statistical models predict general trends in pectus carinatum brace treatment and can assist in creating treatment plans, motivating patient compliance, and can inform the design of future treatment systems.

Developing a nutrition screening tool for children with cystic fibrosis ages 0 to 2 years: Children with cystic fibrosis nutrition screening tool.

BACKGROUND: For children with cystic fibrosis (CF), achieving and maintaining optimal growth by the age of 2 years is critical for future health outcomes. A standardized nutrition screening is needed to identify growth problems, enable timely interventions, and improve nutritional outcomes for children (0 to 2 years) with CF. The purpose of this study was to develop a nutrition screening tool for children (0 to 2 years) with CF to identify nutrition risk at every clinical encounter. METHODS: A retrospective cross-sectional study was used to develop a nutrition screening tool to determine if nutrition interventions needed to change (at-risk) or continue (not at-risk). Retrospective data for pertinent nutrition factors were collected for 99 children attending an accredited CF clinic. The nutrition factors were compared to a dietitian assessment. A stepwise discriminant analysis determined weight-for-age (WFA) and weight-for-length (WFL) z-scores were significant. Then anthropometric data and corresponding dietitian assessment results were collected for children with CF attending two other accredited CF clinics (n = 29, n = 30). Discriminant analysis was used to determine sensitivity and specificity of the nutrition factors and to create a nutrition screening tool equation. RESULTS: The nutrition screening model that included WFA z-score, LFA z-score, WFL z-score, and weight change velocity adequacy determined nutrition risk the best. The sensitivity was 89.7 %, specificity 83.2 %, NPV 93.3 %, and PPV 75.4 % for this model. CONCLUSION: The nutrition screening tool equation developed in this study standardizes the process to identify children (0 to 2 years) with CF at nutrition risk. Further validation is needed.

Area-Selective Atomic Layer Deposition of ZnO on Si\SiO2 Modified with Tris(dimethylamino)methylsilane.

Delayed atomic layer deposition (ALD) of ZnO, i.e., area selective (AS)-ALD, was successfully achieved on silicon wafers (Si\SiO2) terminated with tris(dimethylamino)methylsilane (TDMAMS). This resist molecule was deposited in a home-built, near-atmospheric pressure, flow-through, gas-phase reactor. TDMAMS had previously been shown to react with Si\SiO2 in a single cycle/reaction and to drastically reduce the number of silanols that remain at the surface. ZnO was deposited in a commercial ALD system using dimethylzinc (DMZ) as the zinc precursor and H2O as the coreactant. Deposition of TDMAMS was confirmed by spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), and wetting. ALD of ZnO, including its selectivity on TDMAMS-terminated Si\SiO2 (Si\SiO2\TDMAMS), was confirmed by in situ multi-wavelength ellipsometry, ex situ SE, XPS, and/or high-sensitivity/low-energy ion scattering (HS-LEIS). The thermal stability of the TDMAMS resist layer, which is an important parameter for AS-ALD, was investigated by heating Si\SiO2\TDMAMS in air and nitrogen at 330 °C. ALD of ZnO takes place more readily on Si\SiO2\TDMAMS heated in the air than in N2, suggesting greater damage to the surface heated in the air. To better understand the in situ ALD of ZnO on Si\SiO2\TDMAMS and modified (thermally stressed) forms of it, the ellipsometry results were plotted as the normalized growth per cycle. Even one short pulse of TDMAMS effectively passivates Si\SiO2. TDMAMS can be a useful, small-molecule inhibitor of ALD of ZnO on Si\SiO2 surfaces.

A retail market study of organic and conventional potatoes (Solanum tuberosum): mineral content and nutritional implications.

Whether or not all foods marketed to consumers as organic meet specified standards for use of that descriptor, or are nutritionally different from conventional foods, is uncertain. In a retail market study in a Western US metropolitan area, differences in mineral composition between conventional potatoes and those marketed as organic were analysed. Potatoes marketed as organic had more copper and magnesium (p < 0.0001), less iron (p < 0.0001) and sodium (p < 0.02), and the same concentration of calcium, potassium and zinc as conventional potatoes. Comparison of individual mineral concentrations between foodstuffs sold as organic or conventional is unlikely to establish a chemical fingerprint to objectively distinguish between organic and conventional produce, but more sophisticated chemometric analysis of multi-element fingerprints holds promise of doing so. Although statistically significant, these differences would only minimally affect total dietary intake of these minerals and be unlikely to result in measurable health benefits.

Juice, pulp and seeds fractionated from dry climate primocane raspberry cultivars (Rubus idaeus) have significantly different antioxidant capacity, anthocyanin content and color.

Raspberries contain flavonoid antioxidants whose relative concentrations may vary between the juice, pulp, and seed fractions. Oxygen radical absorbance capacity (ORAC), total anthocyanin content, and berry color were determined for six cultivars of primocane raspberries grown in a dry climate (Utah, USA). Significant ORAC differences were found between juice (18.4 ± 0.39 µmol TE/g), pulp (24.45 ± 0.43), and seeds (273.27 ± 11.15) with all Utah cultivars combined. A significantly higher concentration of anthocyanins was present in Utah raspberry juice (20.86 ± 0.35 mg cyanidin-3-glucoside eq./100 g), compared to pulp (13.96 ± 0.35). Anthocyanin content of juice and pulp were significantly positively correlated with dark color (L*). This is the first report of fractional differences in dry climate raspberries, and has implications for the juice and supplement industries.

Kinematic changes during a marathon for fast and slow runners.

UNLABELLED: The purpose of this study was to describe kinematic changes that occur during an actual marathon. We hypothesized that (1) certain running kinematic measures would change between kilometres 8 and 40 (miles 5 and 25) of a marathon and (2) fast runners would demonstrate smaller changes than slow runners. Subjects (n = 179) were selected according to finish time (Range = 2:20:47 to 5:30:10). Two high-speed cameras were used to measure sagittal-plane kinematics at kilometres 8 and 40 of the marathon. The dependent variables were stride length, contact time, peak knee flexion during support and swing, and peak hip flexion and extension during swing. Two-tailed paired t-tests were used to compare dependent variables between kilometres 8 and 40 for all subjects, and regression analyses were used to determine whether faster runners exhibited smaller changes (between miles 5 and 25) than slower runners. For all runners, every dependent variable changed significantly between kilometres 8 and 40 (p < 0.001). Stride length increased 1.3%, contact time increased 13.1%, peak knee flexion during support decreased 3.2%, and peak hip extension, knee flexion, and hip flexion during swing decreased 27.9%, increased 4.3%, and increased 7.4%, respectively (p < 0.001). Among these significant changes, all runners generally changed the same from kilometres 8 and 40 except that fast runners decreased peak knee flexion during support less than the slow runners (p < 0.002). We believe that these changes, for all runners (fast and slow), were due to fatigue. The fact that fast runners maintained knee flexion during support more consistently might be due to their condition on the race day. Strengthening of knee extensor muscles may facilitate increased knee flexion during support throughout a marathon. KEY POINTS: Runners changed kinematics significantly from kilometres 8 to 40 (increased stride length, contact time, peak hip flexion during swing, and peak knee flexion during swing, and decreased running speed, stride frequency, peak knee flexion during support and peak hip extension during swing).Fast runners demonstrated more peak knee flexion during support throughout a marathon.Runners generally changed kinematics similarly (between kilometres 8 and 40) except that fast runners exhibited a more consistent peak knee flexion during support than slow runners.Resistance training that would increase both muscular strength and endurance of knee extensors may increase peak knee flexion during support and help maintain it similar to the fast runners throughout a marathon.