Training Miles Research Articles

The Development and Initial Assessment of a Novel Heart Rate Training Formula

The Development and Initial Assessment of a Novel Heart Rate Training Formula

Medical Care and Runner Characteristics at a 161-km High Altitude Ultraendurance Run in Colorado, 2014

To examine reported medical events, medical care provided, runner training, and racing characteristics at a high altitude ultramarathon run. Medical personnel reported all significant events to the Race Medical Director during and after the event. Significant medical events were followed up after the race by either the Medical Director or another race medical provider. Seventy-four runners completed an online postrace questionnaire regarding their experience, symptoms during and after the run, training characteristics, medication use, hydration and fueling strategy, and injuries both during the run and in prior ultramarathons. Associations between the medical problems experienced during the race and the runner’s hydration, training, and experience were examined. Fifty-four percent of runners reported fewer than ten 161-km races, 51% had more than 20 years of running experience, and >75% had more than 7 years of ultramarathon experience. Years of running and years of running ultras were not significantly associated with any of the medical outcomes. Peak training miles per week was significantly negatively correlated with shortness of breath (P = .0316). Fifty percent of racers drank to thirst only, 39% on a time schedule and 16% by urine color or amount. The most frequent medical problems experienced during the race were nausea and vomiting (37%), blisters (34%), and shortness of breath (24%). Twenty-three racers reported using pain medication during the race, mainly NSAIDs (nonsteroidal anti-inflammatory drugs). No definite serious altitude illness was reported despite the high altitude during much of the race. No runner received intravenous fluids during or after the race. This group of experienced runners appeared to tolerate high altitude within the race, by report. Medical issues were largely minor in nature. Running experience did not correlate strongly with reported symptoms. More study is needed, at this distance and altitude, regarding runner acclimatization practices, serum sodium, body weight, and ADH (antidiuretic hormone) levels as relates to hydration strategy and the possible effects of NSAIDs on the development of altitude illness.

A survey on orthopedic injuries during a marathon sled dog race.

PurposeThis prospective observational study aimed to describe and quantify orthopedic injuries (OI) during a marathon sled dog race that led to discontinuation of racing (dropped dogs [DDs]) and to suggest potential associations with risk factors during the event.Study designProspective observational study.AnimalsA total of 989 Nordic breed endurance sled dogs that participated in the 2011 Iditarod Sled Dog Race. Data were collected via an extensive questionnaire, medical records, and speed calculations based on Global Positioning System equipment on each dog sled. OI risk factors and DD incidence were statistically analyzed on dogs and teams completing at least half the race distance, including Student’s t-test, Pearson’s chi-squared test, Poisson regression, and various frailty analysis models as indicated. Significance was set at P<0.10 for inclusion in the models with trends established at P≤0.10 and significance declared at P<0.05.ResultsQuestionnaire response was 40.3%. DD incidence was 38.3%, most often due to OI (50.6%). OI occurred most frequently in the thoracic limb (43.3%) compared with pelvic limb injuries (7.3%). Increased speed was associated with fewer shoulder injuries (Ratio=0.65, P=0.03). Carpal injuries were positively related with increased conditioning distance (defined as training miles; Hazard ratio =1.61, P=0.02). The risk to become a DD decreased with every year of increased age of the dogs (Hazard ratio =0.92, P=0.03).ConclusionOI, specifically of the shoulder and carpus, are common in marathon sled dogs. Injury risk may be speed-related and decreases with increasing age of the dog. Further study of environmental, dietary, and trail conditions in sled dog racing orthopedic research is needed.

Railroad Operational Performance in the United States

This paper examines the effects of increased car weights, train size, and distance on railroad operational performance, which is measured in revenue ton-miles per train hour. A statistical model is estimated from Class I data that explains most of the variation in this index, while controlling for commodity and fixed network effects. The results suggest that length of haul, net load, and train size contributed significantly to performance gains from 1987 to 2006. However, train miles per track mile increased by 89% during the same period, resulting in line and yard congestion.

Analyses of historical rail accidents to identify accident parameters impacting transport of spent nuclear fuel

As a regulatory authority for the transportation of spent nuclear fuel (SNF) in the USA, the Nuclear Regulatory Commission requires that SNF transportation packages be designed to endure a fully engulfing fire with an average temperature of 800uC (1475uF) for 30 min, as prescribed in Title 10 of the Code of Federal Regulations Part 71. The work described in this paper was performed to support the Nuclear Regulatory Commission in determining the types of accident parameters that could produce a severe fire with the potential to fully engulf an SNF transportation package. This paper describes the process that was used to characterise the important features of rail accidents that would potentially lead to an SNF transport package being involved in a severe fire. Historical rail accidents involving all hazardous material (i.e. all nine classes of hazardous material) and long duration fires in the USA have been analysed using data from the Federal Railroad Administration and the Pipeline and Hazardous Materials Safety Administration. Parameters that were evaluated from these data include, but were not limited to, class of track where the accident occurred, class of hazardous material that was being transported and number of railcars involved in the fire. The data analysis revealed that in the past 34 years of rail transport, roughly 1800 accidents have led to the release of hazardous materials, resulting in a frequency of roughly one accident per 10 million freight train miles (Because all of the data were obtained in the USA, which still uses distance measured in miles, and the primary source is an extensive database from the Federal Railroad Administration that is also in reported in miles, the data in this paper are reported in miles rather than kilometres. Conversion of miles to kilometres is by multiplication of 1?61.). In the last 12 years, there have only been 20 accidents involving multiple car hazardous material releases that led to a fire. This results in an accident rate of 0?003 accidents per million freight train miles that involved multiple car releases and a fire. Out of all the accidents analysed, only one involved a railcar carrying class 7 (i.e. radioactive) hazardous material.

Relationship between Train Length and Accident Causes and Rates

Train accident rates are a critical metric of railroad transportation safety and risk performance. Understanding factors affecting accident rates is also important for evaluating the effectiveness of various accident prevention measures. Accident rates have been the subject of a number of analyses, but these analyses have generally not considered the effect of train length on accident rate. Accident causes can be classified into two groups: those dependent on train length and correlated with the number of cars in the train, and those independent of train length, corresponding to the number of train miles operated. These classifications have implications for the quantitative effect of various changes in railroad operating practices on railroad safety performance. Whether an accident cause is a function of car miles or train miles affects how safety measures that might reduce the likelihood of that cause will affect overall train accident rate. Accident causes have been classified as car mile or train mile related based on expert opinion, but these classifications have not been quantitatively tested. FRA accident data were used to develop a metric to classify objectively accident causes, and 11 causes were reclas-sified from the previous classification. Based on the results of the study, a sensitivity analysis was conducted to evaluate how changes in train length affect individual trains’ accident likelihood and systemwide accident rate. The concept of causes of car mile versus train mile accidents leads to the premise that, although longer trains are expected to experience more accidents than shorter trains, operation of longer trains results in a lower system-level accident rate.

Railroad Accident Rates for Use in Transportation Risk Analysis

Annual safety statistics published by FRA provide train accident counts for various groupings, such as railroad, accident type, cause, track type and class, train length, and speed. However, hazardous materials transportation risk analysis often requires more detailed accident rate statistics for specific combinations of these groupings. The statistics that are presented enable more precise determination of the probability that Class I and non-Class I railroad freight trains will be involved in an accident on various classes of main-line track. An increase in the overall accident rate from 1997 to 2001 can be largely attributed to the increase in yard accidents. During that time, the main-line derailment rate for Class I freight trains remained nearly constant. Track class-specific derailment rates for Class I main-line freight trains show two orders of magnitude difference between the lowest and highest FRA track classes. Depending on the risk analysis question, accounting for these differences in rates will often be important in developing an accurate estimate of risk over the length of a route or at particular locations along a route. A sensitivity analysis suggests that the distribution of freight train miles by FRA track class may have changed since a study conducted by the Association of American Railroads in the early 1990s. More up-to-date estimates of track class-specific accident rates would require new data on this distribution.

The Response of a Bone Resorption Marker to Marine Recruit Training

This study measured the response of deoxypyridinoline, a biomarker of bone resorption, during 11 weeks of Marine recruit training. Urine samples were obtained from 155 female and 58 male Marine recruits from the first morning void every 3 days during training. Training miles of weight-bearing exercise were recorded daily, and injury data were obtained from the medical clinic staff. Deoxypyridinoline was significantly (p < 0.001) increased at week 2 and weeks 9 through 11 for women and at weeks 10 and 11 for men. The increase in bone resorption corresponded to an increase in miles of weight-bearing exercise performed throughout training. The incidence of stress fracture and reaction was 3.9% and 14.8%, respectively, for women and 1.7% and 3.4%, respectively, for men. Significant bone resorption took place at the end of Marine recruit training due to accumulation of weight-bearing exercise throughout training and the increase in marching toward the end.

Food and fluid intake and disturbances in gastrointestinal and mental function during an ultramarathon.

The purpose of this study was to document eating strategies employed by runners during a 160-km race, and to identify eating patterns that predispose the runner to disturbed mental or gastrointestinal functioning. We monitored intake in 19 volunteers during the 12 hours pre-race. Intake was determined by interview with runners approximately every 12 km throughout the race. The mean finish time was 24.3 hours, with 4 runners not completing the race. Body mass decreased during the race, 75.9 +/- 2.3 kg to 74.4 +/- 2.2 kg (p <.001). Runners ingested 2643 kcals during the 12 hours prerace (68% carbohydrate) and 3.8 L of fluid. During the race 6047 kcal, 18 L of fluid, and 12 g of sodium were consumed. Gastrointestinal distress (GI) was experienced by half of the participants, but was unrelated to food or fluid intake. Upper GI symptoms were more prevalent than lower and occurred mainly after 88 km. Runners with GI distress tended to complete fewer training miles (p =.10) and to do shorter training runs (p =.08). Half of the volunteers reported mental status changes (MSC), such as confusion or dizziness. Runners with MSC had greater intake of total calories, carbohydrate, and fluid (p <.05) than runners without MSC. They also completed shorter training runs (p =.03). Caloric and moisture intake for all runners far exceeded intakes described previously. Although intake did not match energy expenditure, it may represent the upper limit for absorption during exercise, and very high food and/or fluid intake appears to lead to perturbed mental status.

OPTIMAL ALTITUDE FOR ???LIVING HIGH-TRAINING LOW???

“Living high (2,500 m) û training low (1,250 m)” improves sea level performance in most endurance athletes. However, the individual variability in this improvement is marked, due at least in part, to a suboptimal erythropoietic response. We hypothesized that living at relatively higher altitudes would lead to greater increases in erythropoietin (EPO), VO2max, and sea level racing performance. Forty-eight competitive runners (32 men, 16 women) participated in: 1) 4 wk sea-level pretest period and supervised training camp; 2) 4 wk of “high-high-low” training camp where groups lived at 1,780 m, 2,085 m, 2,454 m, or 2,805 m and trained together at low to moderate altitude (high intensity workouts 1,250 û 1,780 m; base training 1,700 û 3,000 m) and 3) 2 wk of sea-level post-testing. Subjects were matched for gender, pre-altitude performance, and the percentage incrrease in EPO after 24 hours at a simulated altitude of 2,454 m in a hypobaric chamber and assigned to each living altitude in a balanced randomization. Primary outcome variables included VO2max and 3,000-m time-trial racing performance. Results: There was no difference among groups either for total training miles or number of hard interval sessions. VO2max increased after 4 weeks only at the three highest altitude exposures: 8 ± 85 ml; 206 ± 60 ml; 308 ± 60 ml; and 301 ± 73 ml respectively, with 2,085 m and 2,454 m statistically greater than 1,780 m. Both groups living at 2,085 m and 2,454 m improved 3,000-m time by 2.8 ± 0.7% and 2.7 ± 0.6% respectively; 15.7 ± 4.0 and 16.6 ± 4.2 seconds (p = 0.003 and 0.002) but 1,780 m and 2,805 m did not (1.1 ± 0.05% and 1.4 ± 1.1%; 6.3 ± 3.1 and 9.0 ± 7.1 s respectively). Conclusion: The optimal living altitude for “high-low” training appears to be 2,000 û 2,500 m. We speculate that < 1,800 m may be too low (possibly due to inadequate erythropoiesis) and ± 2,800 m may be too high due to negative aspects of altitude acclimatization.

Reversal of runner's bradycardia with training overstress.

To elicit a criterion elevation (> 10%) in resting heart rate (HR) with training overstress, and subsequently test the hypothesis that such "reversed bradycardia" (RB) negatively affects running performance. Prospective before-and-after intervention with a comparison group. General community. 21 healthy male marathon runners. Voluntary doubling of training miles on 14 consecutive days. Left ventricular (LV) function by echocardiography, HR, and plasma epinephrine (PE) at rest and during submaximal exercise, and 15 km road run performance. Two days after the training overstress, 12 runners met the criterion (RB group), showing an average elevation in resting HR of 16% (range: 11 to 23%). The RB group also exhibited hyperkinetic LV shortening (p < 0.05), elevated exercise HR (p < 0.001), increased PE at rest and during exercise (p < 0.05), and reduced 15 km performance (p < 0.05). The other nine runners who maintained a stable resting HR during the intervention showed no significant outcome changes. In addition to muscular overuse, heightened sympathetic drive likely contributed to the observed reversal of bradycardia. The development of this stress-related cardiac perturbation was associated with a decrement in running performance, confirming the hypothesis.

CARDIORESPIRATORY RESPONSE TO MAXIMAL ARM AND LEG EXERCISE IN NATIONAL CLASS MARATHON RUNNERS.

684 Marathon runners (MR) are among the most aerobically fit athletes in the world. Although aerobic capacity (V̇O2 max) during arm exercise in healthy men generally varies between 64 and 80% of leg V̇O2 max ( = 70%), few data are available regarding the arm fitness of MR. Methods: To clarify the relationship between arm and leg fitness in MR, we studied 10 national class MR (±SD age=30±4 yrs; 70±8 training miles per week) whose best marathon times averaged <2 hrs, 35 min. Each MR underwent lower and upper body maximal exercise testing with direct measurement of cardiorespiratory (CR) variables using a treadmill (standard Bruce protocol) and arm crank ergometer, respectively. Results: Selected maximal data (±SD) during arm and leg testing were: (Table)TableMaximal CR responses were significantly greater during leg than arm exercise. Relative arm fitness (arm V̇O2 max/leg V̇O2 max) was extremely variable (range 41% to 76%) and averaged 59±13%. Conclusion: Although MR are able to achieve significantly higher V̇O2 max values than those observed in the general population, their relative arm fitness appears to be slightly reduced. These findings add to and strongly support the specificity of measurement and training concept.

Nutrition for Cyclists

Good nutrition is important at every stage of training and competition. Both the serious competitive cyclist as well as the recreational cyclist should eat a balanced diet that provides calories adequate to meet energy demands. Athletes consuming less than 2000 calories a day may have difficulty meeting nutrient needs, particularly for iron and calcium. Weight loss, glycogen depletion, and dehydration also are possible results of an inadequate diet. Dietary strategies to enhance or maintain the body's carbohydrate stores are necessary for performance, especially for cyclists with high training miles or participating in road racing and other endurance events. Additionally, cyclists should be encouraged to drink plenty of fluids, especially when in a hot environment. It appears that protein requirements of endurance athletes increase as the duration and intensity of exercise increases. However, factors such as total calorie intake and protein quality should be considered when determining protein needs. Many athletes are concerned about vitamin and mineral intake and often use nutritional supplements both for "insurance" as well as performance reasons. The supplements taken most often include vitamin C, the B-complex, and iron. Vitamins and minerals in excess of the RDA do not improve performance and can be toxic when consumed in large amounts. On the other hand, vegetarians and cyclists with low-calorie intakes may benefit from a multivitamin or mineral supplement.

Physical training and personality factors as predictors of marathon time and training injury.

On the basis of surveys completed by 105 male participants in a popular marathon, a multiple regression analysis was conducted to identify the variables contributing significantly to the prediction of final time. Overall prediction was successful, with R = .896, and training pace was the most important factor in the equation, speedier workouts being associated with faster marathon times. Final time was also related positively to best 10-km race time in the previous 12 mo. and repression-sensitization (faster runners being more sensitized), and negatively to maximum number of training miles in a single week, number of previous marathons completed, and number of days of training lost through illness or injury. Contrary to expectations, locus of control was not related to final time. Only 27% of the runners had lost training time through injury, but a discriminant analysis showed that, compared to those who had avoided this problem, the injured were younger, rested less, ran less in the week prior to the marathon, ran a slightly longer long run but ran it earlier before the race, and ran fewer runs of 20 miles or more. It is suggested that researchers should study the repression-sensitization variable and investigate injury in runners preparing for a marathon.

The Acute and Prolonged Effects of Marathon Running on 20 Blood Parameters

In brief: Abnormal blood chemistry values may be a normal physiological response to marathon running and training. This was shown by elevations in creatine phosphokinase, high density lipoproteins, lactate dehydrogenase, and WBCs after a marathon run. Significant changes(p <.05) were noted in all blood parameters except globulin and high density lipoproteins from subjects before the race to immediately after the race and two to three weeks after the race. Insignificant differences in blood chemistry values were observed in runners with different running speeds, previous marathon experience, age, body weight, and average training miles per week.

The reading railroad's suburban electrification

In spite of a doubling of trains and train miles, and schedules faster by 20 per cent, the cost of suburban operation has been lowered substantially by electrification. Resulting service improvements have changed an appreciable traffic loss to a traffic increase. Important details of the system and its equipment are described here.

Railroad Signaling and Train Control

EFFICIENCY of train operation depends largely upon a system of directing train movements that will insure the maximum utilization of track and equipment capacity and the maximum output of train miles in a unit of time. In the earlier days the time interval method of railway signaling was favored, movements being directed by timetables and train orders. The space interval method is now universally recognized as most satisfactory, train movements being directed by block signals in addition to timetables and train orders. Block signals may be operated manually or automatically by means of a track circuit, the shunting of which by the trains operating upon the rails actuates the apparatus.

Railroad signaling and train control

EFFICIENCY of train operation depends largely upon a system of directing train movements that will insure the maximum utilization of track and equipment capacity and the maximum output of train miles in a unit of time. In the earlier days the time interval method of railway signaling was favored, movements being directed by timetables and train orders. The space interval method is now universally recognized as most satisfactory, train movements being directed by block signals in addition to timetables and train orders. Block signals may be operated manually or automatically by means of a track circuit, the shunting of which by the trains operating upon the rails actuates the apparatus.

A Comparison of the Cost of Transport and Ton-Miles by Land, Sea, and Air

All methods of transport must be judged by their cost of operation and the revenue they produce, and the comparison, therefore, of the cost of ton-miles provides a useful but not the only basis from which conclusions can be drawn as to the efficiency and utility of such services. Vehicle, train, ship, or air miles and their cost must also be considered as well as ton-miles, and above all the factors of speed and the completeness of the service from the point of view of the user must be taken into account.We have seen during the last few years attempts made to bolster up certain methods of transport on the ground that they are beneficial as a whole to the community, to special trades, or to the welfare of particular places or classes. But sooner or later the practice of subsidising any kind of transport out of taxes or rates, or out of the proceeds of other allied concerns, will have to be recognised as unsound, though there are exceptional cases where one service is naturally complementary to another kind of service, and in the end the methods of transport that will survive will be those that can stand upon their own bases.