10-km Run Research Articles

Predictors of Running-Related Injuries Among 930 Novice Runners: A 1-Year Prospective Follow-up Study.

Background:To identify persons at high risk of sustaining running-related injuries, an evidence-based understanding of the risk factors associated with injury is needed.Purpose:To identify demographic and behavioral risk factors associated with running-related injuries.Study Design:Observational prospective cohort study with a 1-year follow-up.Methods:Exposures including sex, age, body mass index (BMI), behavior (Type A Self-Rating Inventory [TASRI]), running experience, other sports activity, previous running-related injuries, and other injuries not related to running were assessed prior to or at baseline. The outcome of interest was a running-related injury, defined as any musculoskeletal complaint of the lower extremity or back caused by running that restricted the amount of running (volume, duration, pace, or frequency) for at least 1 week. All participants quantified their running volume by global positioning system (GPS) and used a neutral running shoe. Time to first injury for each exposure variable was analyzed using a generalized linear model, with cumulative kilometers of the training sessions as the time scale.Results:A total of 930 individuals were included in the study, of which 254 sustained a running-related injury during a total of 155.318 km of running. By calculating the cumulative injury risk differences (cIRDs) [95% confidence intervals] after 500 km of running, the TASRI Type B behavior (cIRD, 11.9% [−0.5%; 23.3%]; P = .04) was found to be a significant predictor of injury, while age between 45 and 65 years (cIRD, 14.7% [−2.1%; 31.5%]; P = .08) and previous injuries not related to running (cIRD, 11.1% [−0.2%; 22.4%]; P = .05) were considered clinically interesting, although not statistically significant. In addition, χ2 test results across 4 BMI groups also revealed a borderline significant relationship (P = .06). No significant or clinically relevant relationships were found for sex (P = .42), previous running-related injury (P = .47), running experience (P = .30), and other sports activities (P = .30).Conclusion:The findings of the present study suggest BMI >30 kg/m2, age between 45 and 65 years, noncompetitive behavior, and previous injuries not related to running are associated with increased risk of injury among novice runners, while BMI <20 kg/m2 was protective. Still, the role of the risk factors in the causal mechanism leading to injury needs to be investigated.

Case Study: Nutrition and Hydration Status during 4,254 km of Running Over 78 Consecutive Days

The aims of this study were to assess the dietary intake and monitor self-reported recovery quality and clinical symptomology of a male ultra-endurance runner who completed a multiday ultra-endurance running challenge covering 4,254 km from North Scotland to the Moroccan Sahara desert over 78 consecutive days. Food and fluid intakes were recorded and analyzed through dietary analysis software. Body mass (BM) was determined before and after running each day, and before sleep. Clinical symptomology and perceived recovery quality were recorded each day. Whole blood hemoglobin and serum ferritin were determined before and after the challenge. Total daily energy (mean ± SD: 23.2 ± 3.2 MJ · day(-1)) and macronutrient intake (182 ± 31 g · day(-1) protein, 842 ± 115 g · day(-1) carbohydrate, 159 ± 55 g · day(-1) fat) met consensus nutritional guidelines for endurance performance. Total daily water intake through foods and fluids was 4.8 ± 2.0 L · day(-1). Water and carbohydrate intake rates during running were 239 ± 143 ml · h(-1) and 56 ± 19 g · h(-1), respectively. Immediately after running, carbohydrate and protein intakes were 1.3 ± 1.0 g · kg BM(-1) and 0.4 ± 0.2 g · kg BM(-1), respectively. Daily micronutrient intakes ranged from 109 to 662% of UK RNIs. Prerunning BM was generally maintained throughout. Overall exercise-induced BM loss averaged 0.8 ± 1.0%; although BM losses of ≥ 2% occurred in the latter stages, a reflection of the warmer climate. Varying degrees of self-reported perceived recovery quality and clinical symptomology occurred throughout the challenge. This case study highlights oscillations in dietary habits along 78 consecutive days of ultra-endurance running, dependent on changes in ambient conditions and course topography. Nevertheless, nutrition and hydration status were maintained throughout the challenge. Despite dietary iron intake above RNI and iron supplementation, this alone did not prevent deficiency symptoms.

Graduated Compression Stockings for Runners: Friend, Foe, or Fake?

To assess the effect of graduated compression stockings (GCS) on lower leg volume and leg complaints in runners during and after exercise. Cross-sectional study. Radboud University Nijmegen Medical Centre and an outdoor running track in Nijmegen, The Netherlands. Thirteen Dutch trained recreational runners. Participants used a GCS on 1 leg during running. (1) Lower leg volume of both legs was measured at baseline, directly after running, and at 5 minutes and 30 minutes after running using a validated perometer. (2) Leg complaints were reported on questionnaires at set intervals. (1) In both experiments, the legs with GCS showed a reduction in mean (± SEM) leg volume directly after running, as compared with the leg without GCS: -14.1 ± 7.6 mL (P = .04) for the 10-km running track and -53.5 ± 17.8 mL (P = .03) for the maximum exercise test. This effect was not observed at 5 and 30 minutes after running. (2) No differences in leg complaints were reported in either experiment. The GCS prevented an increase in leg volume just after the running exercise. However, this result was not accompanied by a reduction in subjective questionnaire-reported leg complaints. The practical consequences of the present findings need further study.

Incremental test design, peak ‘aerobic’ running speed and endurance performance in runners

Peak running speed obtained during an incremental treadmill test (Vpeak) is a good predictor of endurance run performance. However, the best-designed protocol for Vpeak determination and the best Vpeak definition remain unknown. Therefore, this study examined the influence of stage duration and Vpeak definition on the relationship between Vpeak and endurance run performance. Relationship. Twenty-seven male, recreational, endurance-trained runners (10-km running pace: 10-17 k mh(-1)) performed, in counterbalanced order, three continuous incremental treadmill tests of different stage durations (1-, 2-, or 3-min) to determine Vpeak, and two 5-km and two 10-km time trials on a 400-m track to obtain their 5-km and 10-km run performances. Vpeak was defined as either (a) the highest speed that could be maintained for a complete minute (Vpeak-60 s), (b) the speed of the last complete stage (Vpeak-C), or (c) the speed of the last complete stage added to the multiplication of the speed increment by the completed fraction of the incomplete stage (Vpeak-P). The Vpeak determined during the 3-min stage duration protocol was the most highly correlated with both the 5-km (r=0.95) and 10-km (r=0.92) running performances and these relationships were minimally influenced by the Vpeak definition. However, independent of the stage duration, the Vpeak-P provided the highest correlation with both running performances. Incremental treadmill tests comprising 3-min stage duration is preferred to 1-min and 2-min stage duration protocols in order to determine Vpeak to accurately predict 5-km and 10-km running performances. Further, Vpeak-P should be used as standard for the determination of Vpeak.

Gender Difference and Age-Related Changes in Performance at the Long-Distance Duathlon

The differences in gender- and the age-related changes in triathlon (i.e., swimming, cycling, and running) performances have been previously investigated, but data are missing for duathlon (i.e., running, cycling, and running). We investigated the participation and performance trends and the gender difference and the age-related decline in performance, at the "Powerman Zofingen" long-distance duathlon (10-km run, 150-km cycle, and 30-km run) from 2002 to 2011. During this period, there were 2,236 finishers (272 women and 1,964 men, respectively). Linear regression analyses for the 3 split times, and the total event time, demonstrated that running and cycling times were fairly stable during the last decade for both male and female elite duathletes. The top 10 overall gender differences in times were 16 ± 2, 17 ± 3, 15 ± 3, and 16 ± 5%, for the 10-km run, 150-km cycle, 30-km run and the overall race time, respectively. There was a significant (p < 0.001) age effect for each discipline and for the total race time. The fastest overall race times were achieved between the 25- and 39-year-olds. Female gender and increasing age were associated with increased performance times when additionally controlled for environmental temperatures and race year. There was only a marginal time period effect ranging between 1.3% (first run) and 9.8% (bike split) with 3.3% for overall race time. In accordance with previous observations in triathlons, the age-related decline in the duathlon performance was more pronounced in running than in cycling. Athletes and coaches can use these findings to plan the career in long-distance duathletes with the age of peak performance between 25 and 39 years for both women and men.

Cycling Attributes That Enhance Running Performance After the Cycle Section in Triathlon

To determine how cycling with a variable (triathlon-specific) power distribution affects subsequent running performance and quantify relationships between an individual cycling power profile and running ability after cycling. Twelve well-trained male triathletes (VO2peak 4.9 ± 0.5 L/min; mass 73.5 ± 7.7 kg; mean ± SD) undertook a cycle VO2peak and maximal aerobic power (MAP) test and a power profile involving 6 maximal efforts (6 s to 10 min). Each subject then performed 2 experimental 1-h cycle trials, both at a mean power of 65% MAP, at either variable power (VAR) ranging from 40% to 140% MAP or constant power (CON) followed by an outdoor 9.3-km time-trial run. Subjects also completed a control 9.3-km run with no preceding exercise. The 9.3-km run time was 42 ± 37 s slower (mean ± 90% confidence limits [CL]) after VAR (35:32 ± 3:18 min:s, mean ± SD) compared with CON cycling (34:50 ± 2:49 min:s). This decrement after VAR appeared primarily in the first half of the run (35 ± 20 s; mean ± 90% CL). Higher blood lactate and rating of perceived exertion after 1 h VAR cycling were moderately correlated (r = .51-.55; ± ~.40) with a larger decrement in run performance. There were no clear associations between the power-profile test and decrement in run time after VAR compared with CON. A highly variable power distribution in cycling is likely to impair 10-km triathlon run performance. Training to lower physiological and perceptual responses during cycling should limit the negative effects on triathlon running.

Born to run. Studying the limits of human performance

It is recognised that regular physical activity and a high level of fitness are powerful predictors of positive health outcomes. There is a long and rich history of significant feats of human endurance with some, for example, the death of the first marathon runner, Pheidippides, associated with negative health outcomes.Early studies on endurance running used X-ray and interview techniques to evaluate competitors and comment on performance. Since then, comparatively few studies have looked at runners competing in distances longer than a marathon. Those that have, tend to show significant musculoskeletal injuries and a remarkable level of adaptation to this endurance load.The TransEurope Footrace Project followed ultra-endurance runners aiming to complete 4,500 Km of running in 64 days across Europe. This pioneering study will assess the impact of extreme endurance on human physiology; analysing musculoskeletal and other tissue/organ injuries, and the body's potential ability to adapt to extreme physiological stress. The results will be of interest not only to endurance runners, but to anyone interested in the limits of human performance.Please see related article: http://www.biomedcentral.com/1741-7015/10/78

Ingesting a high-dose carbohydrate solution during the cycle section of a simulated Olympic-distance triathlon improves subsequent run performance

The well-established ergogenic benefit of ingesting carbohydrates during single-discipline endurance sports has only been tested once within an Olympic-distance (OD) triathlon. The aim of the present study was to compare the effect of ingesting a 2:1 maltodextrin/fructose solution with a placebo on simulated OD triathlon performance. Six male and 4 female amateur triathletes (age, 25 ± 7 years; body mass, 66.8 ± 9.2 kg; peak oxygen uptake, 4.2 ± 0.6 L·min(-1)) completed a 1500-m swim time-trial and an incremental cycle test to determine peak oxygen uptake before performing 2 simulated OD triathlons. The swim and cycle sections of the main trials were of fixed intensities, while the run section was completed as a time-trial. Two minutes prior to completing every quarter of the cycle participants consumed 202 ± 20 mL of either a solution containing 1.2 g·min(-1) of maltodextrin plus 0.6 g·min(-1) of fructose at 14.4% concentration (CHO) or a sugar-free, fruit-flavored drink (PLA). The time-trial was 4.0% ± 1.3% faster during the CHO versus PLA trial, with run times of 38:43 ± 1:10 min:s and 40:22 ± 1:18 min:s, respectively (p = 0.010). Blood glucose concentrations were higher in the CHO versus PLA trial (p < 0.001), while perceived stomach upset did not differ between trials (p = 0.555). The current findings show that a 2:1 maltodextrin/fructose solution (1.8 g·min(-1) at 14.4%) ingested throughout the cycle section of a simulated OD triathlon enhances subsequent 10-km run performance in triathletes.

Hemolysis and Rhabdomyolysis after Marathon and Long Distance Running

Introduction: Hemolysis and rhabdomyolysis may result from prolonged physical activity such as long distance running and marathon. Aim: The aim of this study was to assess the extent of cell damages after 42 km and 180 km of running, and to elucidate possible mechanisms of the membrane damage. The aim of this study was also to examine the effect of a simple dietary supplementation of antioxidative substances such as vitamin E, selenium and zinc. Method: A 41-year-old female schoolteacher ran continuously for 24 hours, achieving a total running distance of about 180 km. A group of well trained marathon athletes, 60 men and 10 women with a median age of 36 years, participated in the Beito Marathon in Norway. A smaller group of less trained people, 19 men and 4 women was also followed during the same marathon. Results: The hemolysis associated with marathon involved the apparent release of less than 250 mg hemoglobin per liter into plasma, whereas the 180 km run appeared to induce at least 20 times more hemolysis. The maximum values of released muscle enzymes after 180 km (CK 20.000 U/l), were several orders of magnitude higher than after marathon (CK 416 U/l). Furthermore, the prolonged physical exercise evoked a substantial inflammatory response. Discussion: Mechanical factors alone may cause cell damage, but we hypothesized a contributory role of cellular formation of free oxygen radicals. Moderate doses of vitamin E and selenium given to well trained marathon runners appeared to exert only negligible protective effects, either because the initiating membrane lesion is not directly related to oxidative stress, or because the training itself represented a much stronger antioxidant protection. However, the extensive membrane damages observed in the ultra marathon phase (42 to 182 km) may be accelerated by a collapse of endogenous antioxidants. Thus, although glutathione (GSH) peroxidase appears to operate adequately for several hours of exercise in well trained individuals, it is tempting to presume an ongoing GSH depletion in the 42-to-182 km phase. Conclusion: Systematic training and a balanced diet prior to long distance running and marathon may protect the body from organ disturbances in marathoners and ultra marathoners. Keywords: Cell membrane integrity, exhaustive exercise, free oxygen radicals, GSH peroxidase, glutathione, membrane lesions, oxidative stress, reactive oxygen species, selenium, vitamin E, zinc

Carbohydrate supplementation increases intramyocellular lipid stores in elite runners

The objective was to determine the effects of carbohydrate (CHO) supplementation on exercise-induced hormone responses and post-training intramyocellular lipid stores (IMCL). Twenty-four elite male athletes (28.0±1.2 years) were randomized to receive CHO (maltodextrin solution) or zero energy placebo solution (control group). The high-intensity running protocol consisted of 10×800 m at 100% of the best 3000-m speed (Vm3 km) and 2×1000 m maximal bouts in the morning and a submaximal 10-km continuous easy running in the afternoon of day 9. IMCL concentrations were assessed by 1H-MRS before (−day 9) and after training (day 9) in soleus (SO) and tibialis anterior (TA) muscles. Blood hormones were also measured before, during, and post-exercise. The percent change (Δ%) in TA-IMCL was higher in the CHO group (47.9±24.5 IMCL/Cr) than in the control group (−1.7±13.1, respectively) (P=.04). Insulin concentrations were higher in the CHO group post-intermittent running compared to control (P=.02). Circulating levels of free fatty acids and GH were lower in the CHO group (P>.01). The decline in performance in the 2nd 1000-m bout was also attenuated in this group compared to control (P<.001 and P=.0035, respectively). The hormonal milieu (higher insulin and lower GH levels) in the CHO group, together with unchanged free fatty acid levels, probably contributed to the increased IMCL stores. This greater energy storage capacity may have improved post-exercise recovery and thus prevented performance deterioration.

The Physiological Variation of the Retinal Nerve Fiber Layer Thickness and Macular Volume in Humans as Assessed by Spectral Domain–Optical Coherence Tomography

With the introduction of spectral domain-optical coherence tomography (SD-OCT), changes in retinal nerve fiber layer (RNFL) thickness and macular volume (MV) can be detected with high precision. The aim of this study was to determine whether there is a physiological quantifiable degree of variation of these structures in humans. This study took place during a 10-km charity run at VU University Medical Center Amsterdam. Weight, height, hydration status, RNFL thickness (ring scan, 12° around the optic nerve head), and MV (20° × 20°) were assessed in 69 subjects (44 runners, 25 controls) using SD-OCT with eye-tracking function. The SD-OCT scans were assessed before running (normal status), after running (more dehydrated status), and 1 to 1.5 hours after finishing the run (rehydrated status). Controls were measured at the same time intervals as the runners but did not participate in the running event. Changes over time were assessed by general linear models, correcting for repeated measurements. In runners, a significant increase in both RNFL thickness (94.4 μm [baseline] to 95.2 μm [rehydration], P = 0.04) and MV (288.9 μm [baseline] to 291.0 μm [rehydration], P < 0.001) over time was observed. Controls did not show significant changes over time. Anatomically, the physiological change of RNFL thickness was most marked in the nasal sectors. This prospective study demonstrated a significant physiological variation of the RNFL thickness and MV at a proportion that, on an individual patient level, may be relevant for longitudinal studies in neurodegenerative diseases.

The Effects of 8 Weeks of Endurance Running on Hepcidin Concentrations, Inflammatory Parameters, and Iron Status in Female Runners

Exercise-associated iron deficiency is a common disorder in endurance athletes. The authors investigated the effects of long-term endurance exercise on hepcidin concentrations, inflammatory parameters, and iron status in moderately trained female long-distance runners. Eighteen runners were assigned to either an interval- or a continuous-training exercise group. The physical training consisted of two 3-week progressive overload periods, each followed by a week's recovery, and concluded with a 10- or 21-km competitive run. Samples were taken 6 times during the 8-wk training program, first at baseline (BPre), then after the first and second 3-wk training loads (TPost1, TPost2), after each recovery week (Recovery1 and Recovery2), and poststudy (BPost). Soluble transferrin receptor (sTfR) concentrations were increased in Recovery2 and BPost compared with BPre (p=.02), hemoglobin decreased in TPost1 and TPost2 (p<.001), and red blood cells decreased in TPost2 (p=.01). Hepcidin decreased with time in TPost1 and in BPost compared with BPre (p<.001) and increased in TPost2 compared with TPost1 (p<.001). No differences over time were found for high-sensitivity C-reactive protein. The main findings of the current study indicate that serum hepcidin and sTfR were affected after 8 weeks of endurance running in women. No positive relation was found with inflammation.

Wheel Wear Predictions and Analyses of High-Speed Trains

Wear of wheel profiles is one of the most critical issues affecting cost and performance of railway transportation systems. By altering the profile from the shape originally chosen by the designer, wear has a very large effect on vehicle dynamics, so that excessive modifications of the original have to be recovered by griding and re-profiling the wheel to its original profile. Clearly, with high-speed train development, wheel profile design has been driven by keeping high level of passenger comfort and running safety and low track aggressiveness performances. A reliable wheel profile wear prediction model is developed and applied to a vehicle operating high-speed rail lines in China. The methodology is based on wheel wear simulations which are performed based on actual track data, and pertinent operating conditions. The vehicle model is built in the Simpack MBS software utilising validated suspension models. The contact between wheel and rail is modelled with an equivalent ellipse method and Kalker’s simplified theory (FASTSIM). The wear modelling is based on Archard’s wear model. Finally, validation against wheel profile measurements is performed by simulating approximately 240,000 km of running. Comparisons between simulated and measured wheel profiles, including four wheel wear indexes are presented. The agreement is generally very good.

The effect of aronia, montmorency, and Prunus mume supplementation on blood fatigue factors and muscle damage enzymes after running 10 km

The purpose of this study was to analyze the effects of intake of aronia, montmorency, and Prunus mume on 10 km endurance exercise by investigating changes in blood lactate, ammonia, creatine kinase (CK), and lactate dehydrogenase (LDH), and eventually to recommend them as ergogenic aids, which are effective for recovering from exercise fatigue and muscle damage. The subjects were divided into a P. mume intake group, an aronia intake group, a montmorency intake group, and a control group. Blood samples were taken from the brachial vein at rest, and at 0, 30 min, and 24 hr after running to measure recovery status. All data were analyzed by a two-way repeated-measures analysis of variance using SPSS. The results are summarized as follows: The changes in blood ammonia and LDH concentration following 10 km of running were not significantly different among the groups. However, lactate and CK recovery ratio increased significantly in the aronia and montmorency groups compared to those in the P. mume and control groups. In particular, CK concentration was significantly different in the montmorency group compared to that in the other groups. These results suggest that the effects of aronia and montmorency are associated with improved recovery from muscle fatigue and damage induced by highly intensive exercise, endurance exercise, or overtraining. In particular, montmorency is recommended as an ergogenic aid to inhibit muscle pain resulting from high-intensity endurance exercise.

Landing Pattern Modification to Improve Patellofemoral Pain in Runners: A Case Series

Case series. Patellofemoral pain is a common overuse injury in runners. Recent findings suggest that patellofemoral pain is related to high-impact loading associated with a rearfoot strike pattern. This case series describes the potential training effects of a landing pattern modification program to manage patellofemoral pain in runners. Three female runners with unilateral patellofemoral pain who initially presented with a rearfoot strike pattern underwent 8 sessions of landing pattern modification program using real-time audio feedback from a force sensor placed within the shoe. Ground reaction forces during running were assessed with an instrumented treadmill. Patellofemoral pain symptoms were assessed using 2 validated questionnaires. Finally, running performance was measured by self-reported best time to complete a 10-km run in the previous month. The runners were assessed before, immediately after, and 3 months following training. The landing pattern of runners was successfully changed from a rearfoot to a nonrearfoot strike pattern after training. This new pattern was maintained 3 months after the program. The vertical impact peak and rates of loading were shown to be reduced. Likewise, the symptoms related to patellofemoral pain and associated functional limitations were improved. However, only 1 of the participants reported improved running performance after the training. This case series provided preliminary data to support further investigation of interventions leading to landing pattern modification in runners with patellofemoral pain. Therapy, level 4.

Relação entre a cinética do consumo de oxigênio e a estratégia de corrida em uma prova de 10km

Este estudo examinou a influência da cinética on do consumo de oxigênio (&lt;img border=0 width=32 height=32 id="_x0000_i1082" src="../../../../img/revistas/rbme/v17n5/img01.jpg"&gt;O2) sobre a estratégia de corrida adotada durante uma corrida de 10km em corredores com diferentes níveis de desempenho. Vinte e um corredores (28,5 ± 5,3 anos; 172,6 ± 7,3cm; 66,3 ± 9,3kg) realizaram: 1) um teste com incrementos de 1,2km.h-1 a cada três min até a exaustão; 2) um teste de seis minutos de velocidade constante a 9km.h-1 para identificar a cinética do &lt;img border=0 width=32 height=32 id="_x0000_i1081" src="../../../../img/revistas/rbme/v17n5/img01.jpg"&gt;O2; e 3) uma simulação de prova de 10km. Os sujeitos foram divididos em moderada (MP) e baixa (BP) performance de acordo com o tempo gasto para completar a prova de 10km. A velocidade média (MP = 16,9 ± 0,8 vs. BP = 14,9 ± 1km.h-1) na prova de 10km diferenciou significativamente (p &lt; 0,05) entre os grupos. Não foram encontradas diferenças (p &gt; 0,05) entre os grupos em nenhum dos parâmetros cinéticos analisados. Entretanto, a amplitude de aumento do &lt;img border=0 width=32 height=32 id="_x0000_i1080" src="../../../../img/revistas/rbme/v17n5/img01.jpg"&gt;O2 (parâmetro A1) foi inversamente correlacionado com a velocidade média (r = -0,48, p &lt; 0,05) e com as parciais de velocidade na prova (r entre -0,44 e -0,48, p &lt; 0,05), exceto no último trecho (r = -0,19, p &gt; 0,05). Em conclusão, a cinética do &lt;img border=0 width=32 height=32 id="_x0000_i1079" src="../../../../img/revistas/rbme/v17n5/img01.jpg"&gt;O2 parece não interferir na estratégia de corrida adotada em grupos de corredores com diferentes níveis de performance. Contudo, a correlação do parâmetro A1 com as parciais de velocidade sugere uma influência da economia de corrida sobre a estratégia adotada durante a prova de 10km.

The Influence of a Half-Marathon Race Upon Cardiac Troponin T Release in Adolescent Runners

Post-exercise cardiac troponin T (cTnT) release has been widely reported in adult athletes but limited data is available for adolescents. The aim of this study was to determine the incidence and magnitude of cTnT appearance in a large group of adolescent runners, and to determine any association between cTnT release and personal characteristics of adolescents. We recruited 63 adolescent runners (mean±SD: age 16.4±1.5 years; 10 females) who all completed a simulated half-marathon race (an all-out 21-km run) during routine training. Personal data collected included age, training history, 21-km run performance as well as pre-post exercise serum cTnT levels. Serum cTnT was assayed using a 3rd generation assay. At pre-exercise, cTnT concentrations were below the 0.01 µg/L cTnT detection limit of assay in 58/63 runners. The post-exercise cTnT level (range: <0.01-1.36 µg/L) was significantly (p<0.001) greater than that of the pre-exercise (range: <0.01-0.02 µg/L). After the exercise, 57 (90%) and 44 (70%) subjects had cTnT concentrations above the detection: 0.01, and clinical thresholds: 0.05 µg/L, respectively. Post-exercise cTnT was inversely correlated with training years (r=-0.25, p<0.05) and age (r=-0.31, p<0.05). Compared with runners who had trained for ≥ 3 years, runners with less training experience demonstrated increased post-race cTnT levels (p<0.01). cTnT increases are virtually universal among adolescent runners following a 21-km run during routine training and can reach levels typically diagnostic for acute myocardial infarction potentially initiating diagnostic dilemmas. Adolescents with less training experience had higher post-exercise cTnT.

Personal best times in an Olympic distance triathlon and in a marathon predict Ironman race time in recreational male triathletes

BackgroundThe purpose of this study was to define predictor variables for recreational male Ironman triathletes, using age and basic measurements of anthropometry, training, and previous performance to establish an equation for the prediction of an Ironman race time for future recreational male Ironman triathletes.MethodsAge and anthropometry, training, and previous experience variables were related to Ironman race time using bivariate and multivariate analysis.ResultsA total of 184 recreational male triathletes, of mean age 40.9 ± 8.4 years, height 1.80 ± 0.06 m, and weight 76.3 ± 8.4 kg completed the Ironman within 691 ± 83 minutes. They spent 13.9 ± 5.0 hours per week in training, covering 6.3 ± 3.1 km of swimming, 194.4 ± 76.6 km of cycling, and 45.0 ± 15.9 km of running. In total, 149 triathletes had completed at least one marathon, and 150 athletes had finished at least one Olympic distance triathlon. They had a personal best time of 130.4 ± 44.2 minutes in an Olympic distance triathlon and of 193.9 ± 31.9 minutes in marathon running. In total, 126 finishers had completed both an Olympic distance triathlon and a marathon. After multivariate analysis, both a personal best time in a marathon (P < 0.0001) and in an Olympic distance triathlon (P < 0.0001) were the best variables related to Ironman race time. Ironman race time (minutes) might be partially predicted by the following equation: (r2 = 0.65, standard error of estimate = 56.8) = 152.1 + 1.332 × (personal best time in a marathon, minutes) + 1.964 × (personal best time in an Olympic distance triathlon, minutes).ConclusionThese results suggest that, in contrast with anthropometric and training characteristics, both the personal best time in an Olympic distance triathlon and in a marathon predict Ironman race time in recreational male Ironman triathletes.

Physiological Effect of Pacing Tactics and Thermal Stress During 10-km Running

When allowed to free choice, runners adopt a U shaped pattern of pacing during middle distance runs. In high level competition, runners may start at an unreasonably fast pace to stay with their competitors. Our understanding of how pace is regulated when the starting strategy is not freely chosen is incomplete. PURPOSE: We tested the hypothesis that running pace would change reciprocally with core temperature and [La-]. METHODS: Well-trained runners performed three experimental 10-km treadmill race simulations, one freely paced, one with increased starting pace and one with increased starting pace + increased heat stress. Gas exchange, core temperature, [La-] & RPE were measured. RESULTS: During the increased starting pace runs, subjects maintained pace for 2-4 km before slowing. During the final 5-km there was no difference in pace. Core temperature increased equally (37.5 ± 0.2 to 39.5 ± 0.5 °C) in all runs, With no differences in the last 5-km. VO2, HR, ventilation & [La-] increased more rapidly during the forced pace runs, but by 7-km was the same. VO2 averaged 85-90% of VO2max, and HR was >95%max during the last 6-km. By 5-km [La-] was constant between runs and was ∼8 mmol l-1 at the end. RPE was greater during the first 5-km of forced pace, but was not different during the last half. CONCLUSION: The hypothesis of reciprocal changes in pace vs core temperature and blood [La-] was supported. The data support the concept that exercise intensity is modulated in an anticipatory way to limit the magnitude of homeostatic disturbances and that slowing during mid-race may be a strategy to prevent a catastrophic collapse rather than a response to a homeostatic catastrophe.

Changes in Running Kinematics, Kinetics, and Spring-Mass Behavior over a 24-h Run

This study investigated the changes in running mechanics and spring-mass behavior over a 24-h treadmill run (24TR). Kinematics, kinetics, and spring-mass characteristics of the running step were assessed in 10 experienced ultralong-distance runners before, every 2 h, and after a 24TR using an instrumented treadmill dynamometer. These measurements were performed at 10 km·h, and mechanical parameters were sampled at 1000 Hz for 10 consecutive steps. Contact and aerial times were determined from ground reaction force (GRF) signals and used to compute step frequency. Maximal GRF, loading rate, downward displacement of the center of mass, and leg length change during the support phase were determined and used to compute both vertical and leg stiffness. Subjects' running pattern and spring-mass behavior significantly changed over the 24TR with a 4.9% higher step frequency on average (because of a significantly 4.5% shorter contact time), a lower maximal GRF (by 4.4% on average), a 13.0% lower leg length change during contact, and an increase in both leg and vertical stiffness (+9.9% and +8.6% on average, respectively). Most of these changes were significant from the early phase of the 24TR (fourth to sixth hour of running) and could be speculated as contributing to an overall limitation of the potentially harmful consequences of such a long-duration run on subjects' musculoskeletal system. During a 24TR, the changes in running mechanics and spring-mass behavior show a clear shift toward a higher oscillating frequency and stiffness, along with lower GRF and leg length change (hence a reduced overall eccentric load) during the support phase of running.