Risk factors for lower extremity injuries among half marathon and marathon runners of the Lage Landen Marathon Eindhoven 2012: A prospective cohort study in the Netherlands.

To determine risk factors for running injuries during the Lage Landen Marathon Eindhoven 2012. Prospective cohort study. Population-based study. This study included 943 runners. Running injuries after the Lage Landen Marathon. Sociodemographic and training-related factors as well as lifestyle factors were considered as potential risk factors and assessed in a questionnaire 1 month before the running event. The association between potential risk factors and injuries was determined, per running distance separately, using univariate and multivariate logistic regression analysis. In total, 154 respondents sustained a running injury. Among the marathon runners, in the univariate model, body mass index ≥ 26 kg/m(2), ≤ 5 years of running experience, and often performing interval training, were significantly associated with running injuries, whereas in the multivariate model only ≤ 5 years of running experience and not performing interval training on a regular basis were significantly associated with running injuries. Among marathon runners, no multivariate model could be created because of the low number of injuries and participants. This study indicates that interval training on a regular basis may be recommended to marathon runners to reduce the risk of injury.

Effects of wind application on thermal perception and self-paced performance.

Physiological and perceptual effects of wind cooling are often intertwined and have scarcely been studied in self-paced exercise. Therefore, we aimed to investigate (1) the independent perceptual effect of wind cooling and its impact on performance and (2) the responses to temporary wind cooling during self-paced exercise. Ten male subjects completed four trials involving 15 min standardized incremental intensity cycling, followed by a 15-km self-paced cycling time trial. Three trials were performed in different climates inducing equivalent thermal strain: hot humid with wind (WIND) and warm humid (HUMID) and hot dry (DRY) without wind. The fourth trial (W3-12) was equal to HUMID, except that wind cooling was unexpectedly provided during kilometers 3-12. Physiological, perceptual and performance parameters were measured. Subjects felt generally cooler during the WIND than the HUMID and DRY trials, despite similar heart rate, rectal and skin temperatures and a WBGT of ~4 °C higher. The cooler thermal sensation was not reflected in differences in thermal comfort or performance. Comparing W3-12 to HUMID, skin temperature was 1.47 ± 0.43 °C lower during the wind interval, leading to more favorable ratings of perceived exertion, thermal sensation and thermal comfort. Overall, power output was higher in the W3-12 than the HUMID-trial (256 ± 29 vs. 246 ± 22 W), leading to a 67 ± 48 s faster finish time. In conclusion, during self-paced exercise in the heat, wind provides immediate and constant benefits in physiological strain, thermal perception and performance. Independent of physiological changes, wind still provides a greater sensation of coolness, but does not impact thermal comfort or performance.

Factors affecting gross efficiency in cycling.

There is little standardization of how to measure cycling gross efficiency (GE). Therefore, the purposes of these studies were to evaluate the effect of: i) stage duration, ii) relative exercise intensity, iii) work capacity and iv) a prior maximal incremental test on GE. Trained subjects (n=28) performed incremental tests with stage durations of 1-, 3-, and 6-min to establish the effect of stage duration and relative exercise intensity on GE. The effect of work capacity was evaluated by correlating GE with peak power output (PPO). In different subjects (n=9), GE was measured at 50% PPO with and without a prior maximal incremental test. GE was similar in 3- and 6-min stages (19.7 ± 2.8% and 19.3 ± 2.0%), but significantly higher during 1-min stages (21.1 ± 2.7%), GE increased with relative exercise intensity, up to 50% PPO or the power output corresponding to the ventilatory threshold and then remained stable. No relationship between work capacity and GE was found. Prior maximal exercise had a small effect on GE measures; GE was lower after maximal exercise. In conclusion, GE can be determined robustly so long as steady state exercise is performed and RER ≤ 1.0.

Telemetry pill versus rectal and esophageal temperature during extreme rates of exercise-induced core temperature change.

Core temperature measurement with an ingestible telemetry pill has been scarcely investigated during extreme rates of temperature change, induced by short high-intensity exercise in the heat. Therefore, nine participants performed a protocol of rest, (sub)maximal cycling and recovery at 30 °C. The pill temperature (T(pill)) was compared with the rectal temperature (T(re)) and esophageal temperature (T(es)). T(pill) corresponded well to T(re) during the entire trial, but deviated considerably from T(es) during the exercise and recovery periods. During maximal exercise, the average ΔT(pill)-T(re) and ΔT(pill)-T(es) were 0.13 ± 0.26 and -0.57 ± 0.53 °C, respectively. The response time from the start of exercise, the rate of change during exercise and the peak temperature were similar for T(pill) and T(re.) T(es) responded 5 min earlier, increased more than twice as fast and its peak value was 0.42 ± 0.46 °C higher than T(pill). In conclusion, also during considerable temperature changes at a very high rate, T(pill) is still a representative of T(re). The extent of the deviation in the pattern and peak values between T(pill) and T(es) (up to >1 °C) strengthens the assumption that T(pill) is unsuited to evaluate central blood temperature when body temperatures change rapidly.

Relative importance of pacing strategy and mean power output in 1500-m self-paced cycling.

INTRODUCTION: Both mean power output (MPO) and the distribution of the available energy over the race, that is, pacing strategy, are critical factors in performance. The purpose of this study was to determine the relative importance of both pacing strategy and MPO to performance. METHODS: Six well-trained, regionally competitive cyclists performed four 1500-m ergometer time trials (∼2 min). For each subject, the fastest (Fast) and slowest (Slow) time trials were compared and the relative importance of differences in power output and pacing strategy were determined with an energy flow model. RESULTS: The difference in final time between Fast and Slow was 4.0 (2.5) s. Fast was performed with a higher MPO (437.8 (32.3) W vs 411.3 (39.0) W), a higher aerobic peak power (295.3 (36.8) vs 287.5 (34.7) W) and a higher anaerobic peak power (828.8 (145.4) W vs 649.5 (112.2) W) combined with a relatively higher, but not statistically different anaerobic rate constant (0.051 (0.016) vs 0.041 (0.009) W). The changes in MPO (63% anaerobic, 37% aerobic) largely explained the differences in final times. Athletes chose a different pacing strategy that was close to optimal for their physiological condition in both Fast and Slow. CONCLUSION: Differences in intraindividual performance were mainly caused by differences in MPO. Athletes seemed to be able to effectively adjust their pacing profile based on their "status of the day". Keywords modelling performance, energy expenditure, aerobic, anaerobic, sports.

Limitations of temperature measurement in the aural canal with an ear mould integrated sensor.

Aural canal temperature measurement using an ear mould integrated sensor (T(ac)) might be a method suited for continuous non-invasive core temperature estimation in operational settings. We studied the effect of ambient temperature, wind and high intensity exercise on T(ac) and its ability to predict esophageal (T(es)) and rectal temperatures (T(re)). Seven subjects performed a protocol of rest at 21, 10 and 30 °C, followed by exercise and recovery at 30 °C. The subjects performed the protocol twice: with and without face-wind from halfway through the 30 °C rest period. Extra auricle insulation was applied at one side. Ambient temperature changes affected T(ac) significantly, while T(es) and T(re) remained stable. Insulating the auricle reduced but did not abolish this effect. Wind had an immediate cooling effect on T(ac) independent of auricle insulation. During exercise and recovery in 30 °C, T(ac) provided acceptable group predictions of T(re) in trials without wind (bias: -0.66 ± 0.21 °C covered, -1.20 ± 0.15 °C uncovered). Bias was considerably higher with wind, but variability was similar (-1.73 ± 0.11 °C covered, -2.49 ± 0.04 °C uncovered). Individual predictions of T(es) and T(re) showed more variation, especially with wind. We conclude that T(ac) may be used for core temperature assessment of groups in warm and stable conditions.

Anaerobic capacity: effect of computational method.

Anaerobic capacity (AnC) can be estimated by subtracting VO (2) consumed from VO (2) demand, which can be estimated from multiple submaximal exercise bouts or by gross efficiency (GE), requiring one submaximal bout. This study compares AnC using the MAOD and GE method. The precision of estimated VO (2) demand and AnC, determined by MAOD using 3 power output - VO (2) regressions, based on VO (2) from min 8-10 (10 - Y), during min 4 without (4 - Y) and with forced y-intercept (4+Y), and from GE was evaluated by the 95% confidence interval (CI). Well-trained males (n=15) performed submaximal exercise tests to establish VO (2) demand with the MAOD and GE method. To determine AnC subjects completed a constant power output trial. The 3 MAOD procedures and GE method had no significant difference for VO (2) demand and AnC. The 4+Y MAOD procedure and GE method resulted in a smaller 95% CI of VO (2) demand and AnC than the 10 - Y ( P<0.05; P<0.01) and 4 - Y ( P<0.001; P<0.01) MAOD procedures. Therefore, the 4+Y MAOD procedure and GE method are preferred for estimating AnC, but as individual differences exist, they cannot be used interchangeably.

Purification of a candidate gonadotrophin surge-inhibiting/attenuating factor (GnSIF/AF) showing MAPK as a possible target.

Gonadotrophin surge-inhibiting/attenuating factor (GnSIF/AF) has been known for over two decades, but its molecular structure has not been completely characterized yet. In the last 20 years, five different putative GnSIF/AF sequences have been published. In this article, we describe a procedure to isolate and characterize GnSIF/AF from bovine follicular fluid, a GnSIF/AF-derived synthetic peptide (SP-GnSIF/AF) was produced, and the intracellular bioactivity of GnSIF/AF was tested for intracellular action with a MAPK-assay. Two different bioactive molecular weight forms of GnSIF/AF were isolated, a 160 kDa heteromeric and a monomeric 40 kDa protein. The 40 kDa form appeared to be a subunit of the 160 kDa protein. The synthetic peptide mimicked the actions of GnSIF/AF, such as inhibition of GnRH-induced LH secretion and attenuation of the MAPK phosphorylation. The two GnSIF/AF candidates do not show similarities with previously published GnSIF/AF sequences. These are the first data showing the influence of GnSIF/AF on intracellular processes involved in GnRH self-priming and that the biological action of GnSIF/AF was preserved in the produced synthetic peptide. The results provide strong evidence that the identified candidate proteins are the true GnSIF/AF.

Non-invasive continuous core temperature measurement by zero heat flux.

Reliable continuous core temperature measurement is of major importance for monitoring patients. The zero heat flux method (ZHF) can potentially fulfil the requirements of non-invasiveness, reliability and short delay time that current measurement methods lack. The purpose of this study was to determine the performance of a new ZHF device on the forehead regarding these issues. Seven healthy subjects performed a protocol of 10 min rest, 30 min submaximal exercise (average temperature increase about 1.5 °C) and 10 min passive recovery in ambient conditions of 35 °C and 50% relative humidity. ZHF temperature (T(zhf)) was compared to oesophageal (T(es)) and rectal (T(re)) temperature. ΔT(zhf)-T(es) had an average bias ± standard deviation of 0.17 ± 0.19 °C in rest, -0.05 ± 0.18 °C during exercise and -0.01 ± 0.20 °C during recovery, the latter two being not significant. The 95% limits of agreement ranged from -0.40 to 0.40 °C and T(zhf) had hardly any delay compared to T(es). T(re) showed a substantial delay and deviation from T(es) when core temperature changed rapidly. Results indicate that the studied ZHF sensor tracks T(es) very well in hot and stable ambient conditions and may be a promising alternative for reliable non-invasive continuous core temperature measurement in hospital.

Optimal pacing strategy: from theoretical modelling to reality in 1500-m speed skating.

PURPOSE: Athletes are trained to choose the pace which is perceived to be correct during a specific effort, such as the 1500-m speed skating competition. The purpose of the present study was to "override" self-paced (SP) performance by instructing athletes to execute a theoretically optimal pacing profile. METHODS: Seven national-level speed-skaters performed a SP 1500-m which was analysed by obtaining velocity (every 100 m) and body position (every 200 m) with video to calculate total mechanical power output. Together with gross efficiency and aerobic kinetics, obtained in separate trials, data were used to calculate aerobic and anaerobic power output profiles. An energy flow model was applied to SP, simulating a range of pacing strategies, and a theoretically optimal pacing profile was imposed in a second race (IM). RESULTS: Final time for IM was ∼2 s slower than SP. Total power distribution per lap differed, with a higher power over the first 300 m for IM (637.0 (49.4) vs 612.5 (50.0) W). Anaerobic parameters did not differ. The faster first lap resulted in a higher aerodynamic drag coefficient and perhaps a less effective push-off. CONCLUSION: Experienced athletes have a well-developed performance template, and changing pacing strategy towards a theoretically optimal fast start protocol had negative consequences on speed-skating technique and did not result in better performance.

Inadvertent infusion of potassium chloride via an epidural catheter.

A 73-year old man underwent a segmental liver resection for a solitary liver metastasis from a rectal carcinoma. On post-operative day one, an accidental potassium chloride infusion (total 29 mmol or 1135 mg of KCl) was given via the epidural catheter. Within a few hours this resulted in pruritus, progressive muscle spasms, decreased consciousness and vegetative symptoms such as tachycardia and hypertension. Subsequently respiratory insufficiency developed, necessitating intubation and ventilation of the patient with admission to the Intensive Care Unit. The patient received a single dose of 40 mg of dexamethasone intravenously to prevent or decrease possible myelum edema, and 100 ml x h(-1) of NaCl 0.9% infusion over the epidural catheter for several hours. The patient made a complete recovery, was extubated successfully six hours after ICU-admission and discharged home free of symptoms.

Convergence of congenic mapping and allele-specific alterations in tumors for the resolution of the Skts1 skin tumor susceptibility locus.

Although several familial cancer genes with high-penetrance mutations have been identified, the major genetic component of susceptibility to sporadic cancers is attributable to low-penetrance alleles. These 'weak' tumor susceptibility genes do not segregate as single Mendelian traits and are therefore difficult to find in studies of human populations. Previously, we have proposed that a combination of germline mapping and analysis of allele-specific imbalance in tumors may be used to refine the locations of susceptibility genes using mouse models of cancer. Here, we have used linkage analysis and congenic mouse strains to map the major skin tumor susceptibility locus Skts1 within a genetic interval of 0.9 cM on proximal chromosome 7. This interval lies in an apparent recombination cold spot, and corresponds to a physical distance of about 15 Mb. We therefore, used patterns of allele-specific imbalances in tumors from backcross and congenic mice to refine the location of Skts1. We demonstrate that this single tumor modifier locus has a dramatic effect on the allelic preference for imbalance on chromosome 7, with at least 90% of tumors from the congenics showing preferential gain of markers on the chromosome carrying the susceptibility variant. Importantly, these alterations enabled us to refine the location of Skts1 at higher resolution than that attained using the congenic mice. We conclude that low-penetrance susceptibility genes can have strong effects on patterns of allele-specific somatic genetic changes in tumors, and that analysis of the directionality of these somatic events provides an important and rapid route to identification of germline genetic variants that confer increased cancer risk.

Development of indirect potable reuse in impacted areas of the United States.

This paper demonstrates the development of indirect potable reuse (IPR) in the United States. A legislative review and a survey of plants show that IPR is becoming an integral part of water reclamation. Public resistance is the limiting factor to its development while technology is not.

Effects of urinary and recombinant gonadotrophins on gene expression profiles during the murine peri-implantation period.

BACKGROUND: Controlled ovarian stimulation (COS) with urinary gonadotrophins but not recombinant gonadotrophins, adversely affect the implantation process. In this study, we investigated the effects of urinary and recombinant gonadotrophins on gene expression profiles at implantation sites during the mouse peri-implantation period and the possible molecular mechanisms involved in the detrimental effects of urinary gonadotrophins using microarray technology. METHODS: Adult female CD1 mice were treated with (i) urinary human FSH (hFSH) and urinary HCG, (ii) recombinant hFSH and recombinant human LH or (iii) saline. Gene expression profiling with GeneChip mouse genome 430 2.0 arrays, containing 45 101 probe sets, was performed using implantation sites on embryonic day 5. Data were statistically analysed using Significance Analysis of Microarrays. Ten genes from the microarray analysis were selected for validation using quantitative RT-PCR (qRT-PCR). A parallel group of pregnant mice was allowed to give birth to study the effect of gonadotrophins on resorption. RESULTS: Urinary gonadotrophins differentially up-regulated the expression of 30 genes, increased resorption and reduced litter size, whereas recombinant gonadotrophins did not. Nine of the 10 genes were confirmed by qRT-PCR. CONCLUSIONS: Urinary gonadotrophins, but not recombinant gonadotrophins, exerted differential effects on gene expression during the murine peri-implantation period. These findings might contribute to improve protocols for COS, leading to higher successful pregnancy rates.

Urinary gonadotrophins but not recombinant gonadotrophins reduce expression of VEGF120 and its receptors flt-1 and flk-1 in the mouse uterus during the peri-implantation period.

BACKGROUND: Ovarian stimulation in humans might affect the perinatal outcome and be considered as a stress factor in the implantation process. In this study we compared the effects of recombinant and urinary gonadotrophins during the mouse peri-implantation period. METHODS: Adult female CD1 mice were treated as follows (a) urinary hFSH and urinary hCG, (b) recombinant hFSH and recombinant hLH and (c) saline. The effects of the gonadotrophins on the expression of vascular endothelial growth factor120 (VEG120) and its receptors and the corticotrophin releasing hormone (CRH) system during the peri-implantation period were studied. The specific effects of the different gonadotrophins on the onset of implantation were also studied. RESULTS: Urinary gonadotrophin treatment caused lower levels of VEGF120, flt-1 and flk-1 mRNA levels, reduced the size of the embryo implantation site, delayed implantation and prolonged the gestational period. Both urinary hFSH and urinary hCG contributed to the adverse effects. Levels of CRH and CRHR1 expression were not influenced. Recombinant gonadotrophin treatment did not alter any of the parameters studied. CONCLUSIONS: Our results show that the VEGF system of the mouse uterus during the peri-implantation period is adversely affected by urinary gonadotrophins but not by recombinant gonadotrophins. The CRH system was not affected by the two types of gonadotrophins.

Effect of lateral heel wedges on sagittal and transverse plane kinematics of trotting Shetland ponies and the influence of feeding and training regimes.

REASONS FOR PERFORMING STUDY: Lateral heel wedges are used to treat horses and ponies with patella fixation or bone spavin. However, these therapies are purely empirically based and lack scientific evidence. OBJECTIVES: Lateral heel wedges would change joint motion in the sagittal, but mainly in the transversal planes, in healthy horses. This effect would be increased by restricted feeding and decreased by extra training. METHODS: A group of 24 Shetland ponies age 3 years was used, as foals had been assigned to restricted and ad libitum (ad lib) feeding, and low and high level training groups of 6 animals each. An experienced judge evaluated passive patella luxation in the square standing pony, using a score of 0 (normal) to 4 (stationary patella luxation). The motion of the markers, glued to the skin covering skeletal landmarks on the left fore- and hindlimbs, was recorded 3 dimensionally at a frequency of 300 Hz using a modified CODA-3 apparatus while trotting on a treadmill at a speed of 3.0 m/sec, before and directly after 5 degrees lateral heel wedges had been applied to the hindlimbs. After data analysis, the kinematic variables in the sagittal and transversal plane, under these 3 conditions (wedge, feeding, training), were compared statistically using a multivariate repeated measures analysis, general linear model (P < 0.05). RESULTS: In the sagittal plane, an acute change in hind hoof conformation resulted in a less animated trot with a less protracted forelimb and less hindlimb flexion. This is similar, although less pronounced, to the decrease in limb flexion reported previously as a result of restricted feeding. More specifically, lateral heel wedges resulted in significant changes in the transversal plane angles of all joints in the hindlimb. The stifle joint became maximally 1.8 degrees more adducted just before the end of the stance phase, while the tarsal joint was 2.9 degrees and fetlock joint 4.7 degrees more abducted (P < 0.05). In the restricted feeding group, stifle joint adduction was 85 degrees and tarsal joint abduction 5.6 degrees larger than in the ad libitum feeding group (P < 0.05). The patella luxation score was also significantly higher in this group (1.8) compared to ponies fed ad libitum (0.9). CONCLUSIONS: The acute effects of lateral heel wedges on the equine locomotor system in the transversal plane movement relieve tension from the medial patellar ligament and decrease pressure on the medial side of the tarsal joint. However, the fetlock joint experiences considerably more out of plane stress. Poor body condition resulted in a 2x worse patella luxation score, while the effect on stifle and tarsal joint movement in the transversal plane was almost 5x and 2x larger, respectively, than a lateral wedge. POTENTIAL RELEVANCE: The clinical importance of general body condition for maintaining lateral stability in the equine hindlimbs is established, but future research may prove that wedges are beneficial to treat patella fixation and bone spavin in the long term.

Estrogen reduces vascular endothelial growth factor(164) expression in the mouse nucleus paraventricularis of the hypothalamus.

The aim of the present study was to establish whether estrogen and corticosteroids exert effects on vascular endothelial growth factor (VEGF)(164) expression in the hippocampus and nucleus paraventricularis of the hypothalamus by in situ hybridization. Female mice were ovariectomized and treated either with estradiol benzoate or vehicle and male mice were either adrenalectomized or sham-operated. Ovariectomy plus estrogen reduced VEGF(164) expression in the nucleus paraventricularis but not in the hippocampus. Adrenalectomy did not influence VEGF(164) mRNA levels in the hippocampus and nucleus paraventricularis. Our results show for the first time an inhibitory effect of estrogen on VEGF(164) expression in the nucleus paraventricularis and suggest a role for estrogen in the regulation of VEGF(164) expression and function in the central nervous system.

Gonadotrophin stimulation reduces VEGF(120) expression in the mouse uterus during the peri-implantation period.

BACKGROUND: Ovarian stimulation by gonadotrophin treatment exerts negative effects on implantation and embryonic development. We investigated whether gonadotrophin treatment affects VEGF(120) mRNA expression during the peri-implantation period. METHODS: Two groups of adult female CD1 mice were used: the hormone-treated group was injected i.p. with urinary human FSH (5 IU in 0.1 ml saline) and urinary HCG (5 IU in 0.1 ml saline). Spontaneously ovulating mice served as controls and received saline injections. The pregnant mice were killed on embryonic development (ED) days 0, 3, 4, 5 and 6 (day of vaginal plug detection is considered as ED0). The uteri with the implanted embryos were processed for in-situ hybridization for VEGF(120). A separate group of control and hormone-treated pregnant mice were allowed to give birth. Litter size, birthweight and length of gestational period were noted. RESULTS: Gonadotrophin treatment decreased VEGF(120) mRNA levels, delayed implantation, reduced the size of the embryo implantation site on ED5 and ED6 and prolonged the gestational period. CONCLUSIONS: Gonadotrophin treatment reduces VEGF(120) expression which may have serious consequences for normal embryonic development. The present data cannot establish whether this effect is a cause or consequence of delayed implantation.

Effect of an external resistance to airflow on the inspiratory flow curve.

Inhalation is a convenient way to deliver drugs to the respiratory tract in the treatment of respiratory diseases. For dry powder inhalers (DPI's), the principle of operation is to use the patient-generated inspiratory flow as energy source for emptying of the dose system and the delivery of fine drug particles into the respiratory tract. Resistance to airflow of the inhaler device is a major determinant for the inspiratory flow profile through the dry powder inhaler that can be generated by the patient. Therefore, resistance to airflow is one of the design parameters for DPI's, that could be used to control the inspiratory flow profile, and is one of the parameters to optimise particle deposition in the airways. In this study the effect of resistance to airflow on different parameters of the inspiratory flow curves as generated by healthy subjects, asthmatics and COPD patients was determined. As a result of increased resistance to airflow, the peak inspiratory flow (PIF), the flow increase rate (FIR) and the inhaled volume to reach PIF is decreased. On the other hand, the total inhalation time as well as the 80% dwell time is increased. In general, tuning of the resistance to airflow in the design of a dry powder inhaler may improve the drug deposition in the respiratory tract.