Running Race Research Articles

Variable Pacing Is Associated with Performance during the OCC® Ultra-Trail du Mont-Blanc® (2017-2021).

The current evidence suggests that pacing may not be affected by performance level or sex in trail-running races as may occur in road running races. However, the previous studies included races of >100 km. Therefore, we aimed to verify the influence of performance level and sex on pacing in the last four (2017, 2018, 2019, and 2021) editions of a shorter (56.3 km) ultra-trail running race (i.e., Orsières-Champex-Chamonix; OCC®) that maintained the same race profile. The mean finishing time for the 5656 participants was 10 h 20 min 33 s ± 2 h 01 min 19 s. Pacing variability (CV%) was higher in high-level participants, thus showing a greater ability to adapt their pace to the race profile than low-level runners. Males also had a higher pacing variability than females although the effect sizes were small. Based on the current findings, we may recommend for non-elite OCC® participants to adapt their pace to the race profile with a slower pace during uphills and a faster pace during downhills. Further studies including participants' experience are necessary to confirm the effectiveness of this suggestion in trail-running races of variable distances.

The Fastest Tortoise in Town by Howard Calvert

Reviewed by: The Fastest Tortoise in Town by Howard Calvert Kate Quealy-Gainer, Editor Calvert, Howard The Fastest Tortoise in Town; illus. by Karen Obuhanych. Candlewick, 2023 [32p] Trade ed. ISBN 9781536228359 $18.99 Reviewed from digital galleys R* 4-7 yrs Barbara Hendricks, a regular leopard tortoise, has entered a running race. She knows it’s not a great idea and she’s ready to back out, but her owner Lorraine believes in her and Barbara is willing to give it a go. Lorraine sets up a fitness routine, which basically consists of a daily walk, but Barbara sees no progress, outpaced by a worm, a toddler, an old man, and a racecar dinosaur. The day of the race arrives, and Barbara reluctantly goes, only to be horrified by her competition: a slug, a snail, a slow loris, a sloth, and a walrus—“the best of the best,” the fastest animals Barbara has ever seen. Will Barbara be able to keep up and maybe even win the fun run trophy? The race result might not matter for young listeners as they’ll likely be rolling with giggles at the sight of the grimly determined racers slowly—slowly—making their way across several pages of panels, each meeting their own challenge until the tortoise takes first place. The richly textured mixed-media art is vibrant, balancing bright pops of color in the foreground with more subtle hues in the setting, and bespectacled, slightly disheveled Lorraine makes a wonderfully expressive counterpoint to dour, clearly anxious Barbara. The try-your-best message is a familiar one, but it has an irreverent freshness here, especially in the closing pages as a triumphant Barbara sets to race a hare, giving viewers a chance to wonder if her newfound confidence will help her take on faster competition. Copyright © 2022 The Board of Trustees of the University of Illinois

Implementing Modern Technology for Vital Sign Monitoring to Enhance Athletic Training and Sports Performance

(1) Background: Applying medical procedures to keep track of athletes’ metabolic health is a well-known behavior for increasing sports performance. This study’s primary goal was to examine whether implementing a health-screening routine using invasive and non-invasive methods in a mountain running training program can increase sports performance by obtaining a better rank in specific races. (2) Methods: Seven male mountain runners with good results at the international level participated in the research, which featured an initial and a final test. The initial test took place in March at the beginning of the competitive season, and the final test took place in September at the end of the annual training plan in 2021. The entire experiment used invasive tests, such as taking blood samples to perform blood biochemistry analysis, and non-invasive tests, such as mountain running races, determinations of VO2max, EKGs, urine biochemistry and NeuroTracker tests. (3) Results: Comparing the initial test with the final one from a statistical point of view, a significant improvement was found in the final test regarding the obtained results in most tests and, most importantly, the occupied position in the final general rank (p = 0.005). The main variations after effort were decreased Ca++ and increased Cl−, a low TGL level if the diet was inadequate, increased LDH and CPK strongly correlated with the skeletal muscle response, and only physiological changes were found in the EKG and urine summary. (4) Conclusions: The invasive and non-invasive tests applied in this study provided crucial information on the athletes’ health statuses, enabling the coach to adjust the training program in light of the findings in order to improve sports performance and avoid overexertion.

Elite vs. Experienced Male and Female Trail Runners: Comparing Running Economy, Biomechanics, Strength, and Power.

Besson, T, Pastor, FS, Varesco, G, Berthet, M, Kennouche, D, Dandrieux, P-E, Rossi, J, and Millet, GY. Elite vs. experienced male and female trail runners: comparing running economy, biomechanics, strength, and power. J Strength Cond Res 37(7): 1470-1478, 2023-The increased participation in trail running (TR) races and the emergence of official international races have increased the performance level of the world best trail runners. The aim of this study was to compare cost of running (Cr) and biomechanical and neuromuscular characteristics of elite trail runners with their lower level counterparts. Twenty elite (10 females; ELITE) and 21 experienced (10 females; EXP) trail runners participated in the study. Cr and running biomechanics were measured at 10 and 14 km·h-1 on flat and at 10 km·h-1 with 10% uphill incline. Subjects also performed maximal isometric voluntary contractions of knee and hip extensors and knee flexors and maximal sprints on a cycle ergometer to assess the power-torque-velocity profile (PTVP). Athletes also reported their training volume during the previous year. Despite no differences in biomechanics, ELITE had a lower Cr than EXP (p < 0.05). Despite nonsignificant difference in maximal lower-limb power between groups, ELITE displayed a greater relative torque (p < 0.01) and lower maximal velocity (p < 0.01) in the PTVP. Females displayed shorter contact times (p < 0.01) compared with males, but no sex differences were observed in Cr (p > 0.05). No sex differences existed for the PTVP slope, whereas females exhibited lower relative torque (p < 0.01) and velocity capacities (p < 0.01) compared with males. Although not comprehensively assessing all determining factors of TR performance, those data evidenced level and sex specificities of trail runners in some factors of performance. Strength training can be suggested to lower level trail runners to improve Cr and thus TR performance.

Usefulness of V˙O2 Kinetics and Biomechanical Parameters as Predictors of Athlete's Performance in 800 m Running Race.

Incremental tests to exhaustion have been usually employed as the "gold standard" to establish the fitness level of athletes. However, during real competition in many sport disciplines, exertion is not characterized by an increasing effort until failure. The purpose of this preliminary study was to add new evidence regarding the usability of parameters obtained from an on-field testing in 800 m running athletes. V˙O2 kinetics (mean, amplitude, phase time, and phase start time) and biomechanical parameters (velocity, stride frequency, and stride length) were analyzed in eight athletes during a maximal 800 m running race test. Our results showed that only the peak of blood lactate concentration after the 800 m test was correlated with the race time (p = 0.047). The race time was positively associated with both the phase duration and phase start time (all p-values &lt; 0.05). Conversely, race time was negatively correlated with velocity, stride frequency, and amplitude (p-values &lt; 0.05). Our results reveal that jointly studying the V˙O2 kinetics and biomechanical parameters during a maximal 800 m running race test is a useful tool to predict the athlete's upcoming performance and improve the planning and control of the training process of 800 m running athletes.

Central and Peripheral Fatigue in Recreational Trail Runners: A Pilot Study.

Understanding fatigue mechanisms is crucial for exercise performance. However, scientific evidence on non-invasive methods for assessing fatigue in trail running competitions is scarce, especially when vertical kilometer trail running races (VK) are considered. The main purpose of this study was to assess the autonomic nervous system (ANS) activity (i.e., central fatigue) and the state of muscle activation (i.e., peripheral fatigue) before and after a VK competition. A cross-sectional pilot study was performed. After applying inclusion/exclusion criteria, 8 recreational male trail runners (31.63 ± 7.21 yrs, 1.75 m ± 0.05 m, 70.38 ± 5.41 kg, BMI: 22.88 ± 0.48, running experience: 8.0 ± 3.63 yrs, weekly training volume: 58.75 ± 10.35 km) volunteered to participate and were assessed for both central (i.e., via heart rate variability, HRV) and peripheral (via tensiomyography, TMG) fatigue before and after a VK race. After the VK, resting heart rate, RMSSD (p = 0.01 for both) and SDNN significantly decreased (p = 0.02), while the stress score and the sympathetic-parasympathetic ratio increased (p = 0.01 and p = 0.02, respectively). The TMG analyses suggest that runners already suffered peripheral fatigue before the VK and that 20-30 min are enough for muscular recovery after the race. In summary, our data suggest that participants experienced a pre-competition fatigue status. Further longitudinal studies are necessary to investigate the mechanisms underlying fatigue during trail running races, while training periodization and tapering strategies could play a key role for minimizing pre-competition fatigue status.

Impact of collaboration between Basic Life Support-trained first responders and on-site Advanced Life Support service in improving the out-of-hospital cardiac arrest outcome: A case study from the Penang Bridge International Marathon 2019

Sudden cardiac arrest (SCA) in long-distance running races has an incidence rate of 2.18 per 100,000 participants and a high mortality rate. Strategic planning for the medical response in a marathon event is therefore an uphill task for the organizer. Our medical operational model for the Penang Bridge International Marathon (PBIM) has not just improved the survival for marathon-related SCA, but also has been cost-effective for a middle-income country. Two runners from PBIM in 2019 had episodes of cardiac arrest at almost the same time at different locations towards the end of the run route, which were both responded by different teams of Basic Life Support trained volunteers, and then were sent to the Main Medical Base for further Advanced Life Support care before receiving ICU care in the tertiary hospital. Both patients achieved good neurological outcomes and survived hospital discharge.

Correlation between Cardiopulmonary Indices and Running Performance in a 14.5 km Endurance Running Event.

Background: Running is a common recreational activity, and the number of long-distance-race participants is continuously growing. It is well-established that regular physical activity can prevent and manage non-communicable diseases and benefit public health. Training for a long-distance race requires development of specific aerobic abilities and should generate the desired race performance. The purpose of this study was to support the training design and motivation of recreational endurance runners, by investigating whether a 14.5 km race performance of long-distance runners correlates with their cardiopulmonary indices measured in the laboratory. Methods: To examine the relationships of a 14.5 km running performance with the cardiopulmonary parameters of amateur runners, a cross-sectional study design was applied. Fifteen (eleven men and four women) recreational long-distance runners (aged 41.3 ± 9.2 years) from Northern Greece were included in the study and were evaluated in the laboratory within one week before an endurance running race—the 14.5 km Philip Road race, in Greece. The laboratory-based examinations of the athletes consisted of a comprehensive medical pre-participation screening and maximal cardiopulmonary exercise testing. Results: The results showed that the 14.5 km race performance time (73.8 ± 9.7 min) significantly correlated with the cardiopulmonary-exercise-testing speed-related indices at specific submaximal and maximal workloads (p < 0.01, p < 0.05), while the cardiopulmonary indices of oxygen uptake did not reliably predict race running time (p > 0.05). Conclusions: There is a better correlation of the 14.5 km running performance of recreational long-distance runners with the cardiopulmonary-exercise-testing speed-related indices at specific workloads than with the indices of oxygen uptake, running economy or respiratory economy. When preparing a training strategy, amateur long-distance runners should mostly rely on specific running-speed-related laboratory data rather than on oxygen-uptake values.

Development of an Air Pollution Risk Perception Questionnaire for Running Race Runners Based on the Health Belief Model.

An increasing number of individuals participate in running races worldwide; however, running in the presence of air pollution poses health risks to runners. Therefore, developing a valid and reliable instrument is imperative to assess runners’ beliefs and perceptions regarding risks and health behaviors. This study developed a comprehensive questionnaire based on the health behavior model and relevant literature. The questionnaire was tested with 310 responses from individuals with running race experiences in Taiwan. Tests of the measurement model were conducted using reliability and confirmatory factor analysis. The results reveal that the questionnaire consists of eight constructs: perceived susceptibility, perceived severity, perceived benefits, perceived barriers, perceived self-efficacy, cues to action, health behavior intention, and awareness of air quality. The 31 items jointly accounted for 72.71% of the observed variance. All eight factors have good internal consistency, convergent, and discriminant validity with acceptable model fit indexes. Additionally, a valid translated English version of the questionnaire is provided for future research, sports agencies, or governments to explore factors that affect, or interact with, risk while running under air pollution conditions to develop management strategies.

Gender Differences In Participation In Road Race Running Impacted By Covid-19 In The Northeast

Gender Differences In Participation In Road Race Running Impacted By Covid-19 In The Northeast

Uneven but Conservative Pacing Is Associated With Performance During Uphill and Downhill Running.

To investigate the relationship between pacing strategy and performance during uphill and downhill running-specifically, what distribution of energy corresponds to faster race finish times between and among participants. Eighteen years of race data from a 10.2-mile running race with an uphill first half and a downhill second half were analyzed to identify relationships between pacing and performance. A pacing coefficient (PC), equal to a participant's ascent time divided by finishing time (FT), was used to define each participant's pacing strategy. The American College of Sports Medicine metabolic running equation was used to estimate energy expenditure during the ascent, descent, and total race. Statistical analyses compared participants' PC to their FT and finishing place within their age and gender category. Additionally, FT and finishing place were compared between groups of participants who exhibited similar pacing strategies. PCs were positively associated with faster FTs (r2 = .120, P < .001) and better finishing positions (r2 = .104, P < .001). PCs above .600 were associated with the fastest average FTs and best average finishing position within age and gender categories (all P ≤ .047). Participants performed the best when energy expenditure increased no more than 10.4% during the uphill portion compared to their overall average. It is not possible to state that overly aggressive uphill efforts resulted in premature fatigue and thus slower decent times and worse race performance. However, participants should still avoid overly aggressive uphill pacing, as performance was associated with larger PCs.

Sex-related differences and effects of short and long trail running races on resting muscle-tendon mechanical properties.

The purpose of the study was to assess sex-related differences in resting mechanical properties and adaptations of skeletal muscles and tendons in response to trail running races of different distances using multi-site shear wave elastography assessments of the lower limb, force capacity and blood analyses. Sex differences in resting mechanical properties of knee extensor and plantar flexor muscles and tendons were characterized by shear wave velocity (SWV) measurements in healthy males (N=42) and females (N=25) trained in long-distance running. Effects of running distance on muscle and tendon properties were assessed in short (<60 km, N=23) vs. long (>100 km, N=26) distance races. Changes in isometric maximal voluntary contraction torque, serum C-reactive protein and creatine kinase activity were also quantified after running races. Higher SWV of relaxed triceps surae muscle was detected in females as compared to males before running races (+4.8%, p=0.006), but the significant increases in triceps surae muscle group (+7.0%, p=0.001) and patellar tendon SWV (+15.4%, p=0.001) after short-distance races were independent of sex. A significant decrease in triceps surae muscle SWV was found after long-distance races in the whole experimental population (-3.1%, p=0.049). Post-races increase in C-reactive protein and creatine kinase activity were significantly correlated to the relative decreases in triceps surae and quadriceps femoris skeletal muscle SWV (ρ=-0.56, p=0.001 and ρ=-0.51, p=0.001, respectively). Resting mechanical properties of muscles and tendons are affected by sex, and adaptations to trail races are related to running distance. Exercise-induced changes in resting skeletal muscle mechanical properties are associated with enhanced indirect markers of inflammation and muscle damage.

Running pattern changes after a 38-km trail running race: does shoe fatigue play a role?

The aim of this study was to investigate if acute impairments of the footwear midsole materials could interact with the modifications of the running patterns after a fatiguing trail running race. We hypothesized that introducing a control pair of shoes after the race, would modify running mechanics by partially correcting the alterations generated by the deteriorated properties of the shoes worn during the race. Eighteen participants ran on a treadmill at 10 km·h−1 pre- and post-race in three conditions varying the step frequency (free or fixed) or the footwear (control or personal shoes). Spatiotemporal parameters, tibial accelerations across the running conditions and shoe mechanical properties were measured. Significant changes in shoe characteristics (i.e. reduced thickness and increased stiffness) were measured after the race in the personal footwear. At free step frequency, significant changes in contact (+1.3 ± 3.5%) and flight (−19.4 ± 23.7%) times, step frequency (+2.9 ± 2.9%) and peak-to-peak amplitude acceleration at the tibia level (−3.6 ± 18%) were found. The peak-to-peak amplitude of the mediolateral axis showed a significant shoe × time interaction meaning that the control footwear could have had an impact in the running pattern. However, contrary to our hypothesis, no interaction effects were found between the changes in footwear and the changes in spatiotemporal parameters. In conclusion, impairments of shoes characteristics affect impact but not running mechanics.

Sex Differences in Performance and Depth of Field in the United States Olympic Trials.

Jobe, TK, Shaffer, HN, Doci, CL, and Gries, KJ. Sex differences in performance and depth of field in the United States Olympic trials. J Strength Cond Res 36(11): 3122-3129, 2022-Recently, there has been an increased discussion on the role of sex as a variable in human performance. Although there likely remains sociological factors, we can estimate biological sex differences in human performance by comparing finishing times in elite men and women. We sought to determine the effect of sex on running and swimming velocity and depth of field in events of varying lengths in the previous 25 years. Finishing times from United States Olympic trials in running events (100 m to marathon) and freestyle swimming (50-1,500 m) from 1996 to 2021 were collected. Sex differences in velocity were calculated for each year (trends), place (first through seventh), and depth of field (nth place/first place). Significance was set at p ≤ 0.05. Men were 9-13% faster than women in all running events (p ≤ 0.05). The 100-m dash (9%) had the lowest sex difference compared with races of longer distance (p ≤ 0.05). In swimming, men were faster in all events (6-12%, p ≤ 0.05), in which sex differences generally decreased with longer distances. Depth of field was similar between men and women in all running and swimming events. No differences in the analyzed variables were observed from 1996 to 2021. These data suggest that elite men are 9% faster in the 100 m compared with running races of longer distances (~12%). Sex differences in swimmers tended to get smaller as duration increased. Although participation and other sociological factors in these events may play a role, these sex differences warrant further discussion on the role of sex in athletic competition.

A case of encephalopathy following a 10k run

We present the case of a 47-year-old man who was admitted with unexplained delirium. He had taken part in a 10km running race three days before. He was admitted to intensive care one year earlier having presented with vomiting, seizures and encephalopathy. This occurred after a road trip in the USA with frequent steakhouse visits. No definitive diagnosis was made. His sister died at 57 from a presumed encephalitis after chemotherapy for breast cancer, but the diagnosis was uncertain. On initial examina- tion the patient was delirious but neurological examination was unremarkable. Blood tests revealed a low-grade neutrophilia with a normal CRP; ammonia was high (340 micromols/L); CK was normal; plasma amino acid profile showed a high glutamine level (1237micromol/L). EEG findings were in keeping with moderate encephalopathy. Genetic testing revealed hemizygosity for the X-linked pathogenic c. 118&gt;T p.(Arg40Cys) mutation, indicating ornithine transcarbamylase (OTC deficiency). The patient’s clinical state improved with supportive measures. He was referred to a specialist metabolic disorder clinic and has remained well. OTC deficiency is a rare but important cause of hyperammonaemic encephalopathy, which can be fatal. Targeted family history in cases of encephalopathy may be helpful. Diagnosis allows genetic counselling and successful management with straightforward methods including diet and exercise modification, dietary supplementation and “SOS” formulas for times of acute illness. We explore investiga- tion and management for under-recognised, important, causes of hyperammonaemic encephalopathy.claire.carstairs@nhs.net

Relationship between Exercise Intensity and IL-6 Increase during an 80 km Long-Distance Running Race.

Background: IL-6 plasma concentration (IL-6PC) reflects the systemic inflammation related to exercise intensity level. This study aims to describe the IL-6PC kinetics during a long-distance running race. IL-6PC was measured in 20 male runners before (0 km), at each refreshment point (at 21 and 53 km, i.e., k21 and k53, respectively) and at the end of an 80 km long-distance run (k80). Methods: IL-6PC variations (absolute and relative values in each of the three sections (S)) were calculated over S1 (0_k21), S2 (k21_k53) and S3 (k53_k80) and compared with the exercise intensity (duration*race speed) within each section. Results: The mean IL-6PC increased during the run: 2.1 ± 0.6 ng.L−1 at 0 km, 21.0 ± 11.3 ng.L−1 at k21, 38.9 ± 13.0 ng.L−1 at k53 and 49.8 ± 11.9 ng.L−1 at k80. Exercise intensity increased between S1 (24.2 ± 0.5) and S2 (51.9 ± 3.2) (p = 0.04) but not between S2 and S3 (67.4 ± 4.5) (p = 0.69). IL-6PC variation was associated with exercise intensity within S1 (p = 0.03) and S2 (p = 2 × 10−3) and showed at least a trend within S3 (p = 0.06). Conclusions: IL-6PC increases that occur during the early stages of a long-distance run are associated with the running intensity, and then IL-6PC remain stable after the reduction in intensity related to the decrease in running speed.

A Novel Algorithm-based MPPT Strategy for PV Power Systems under Partial Shading Conditions

This paper proposes a new simple method based on the simulation of a short-distance running race in athletics to track the maximum power point (MPP) for photovoltaic (PV) power systems, which can improve the tracking speed and search accuracy. In detail, the DC-DC boost converter is utilized to transfer the power of PV panels to a load and follows the MPP all the time, regardless of the environmental temperature and variant solar irradiance. In the MPP search method based on the proposed short-distance running algorithm (SDRA), an appropriate duty ratio value will be found so that the load receives the highest electrical power from the PV energy system. As a result, the SDRA method has excellent MPP tracking ability with high convergence speed and no oscillation. The efficiency of the proposed method is verified by simulation and experiments. The proposed SDRA method overcomes the obstruction of local traps to achieve global MPP. The results have shown that the SDRA method has advantages in terms of better convergence speed and performance than the particle swarm optimization (PSO) and grey wolf algorithm (GWA) methods when they are operated under the same conditions.

Impact of 5k run race conducted during health-care events on level of physical activity and motivation among health-care professionals in Saudi Arabia

Background: One of the strategic plans of Saudi Arabia's vision for 2030 is the quality-of-life program which calls for increasing the number of people undertaking regular physical activity (PA) from 13% to 40%. The Ministry of Sports and the Saudi Sports for all Federation are key organizations toward achieving the target. Motivation is pivotal to initiating and maintaining PA. Thus, the Saudi Society of Emergency Medicine (SASEM) organized a 5k run race during their annual international scientific conference in February 2022, Riyadh, Saudi Arabia, to motivate PA among health-care workers (HCWs).Purpose: We aim to assess the effect of running a 5k race that was organized in association with a health-care event on the level of PA and motivation among participants.Methodology: We conducted a cross-sectional descriptive study. The data were collected through a valid and reliable tool, the Physical Activity and Leisure Motivation Scale (PALMS) questionnaire. It was distributed as an electronic survey through E-mail and messaging platform (WhatsApp) to all participants in the SASEM 5k run race. We collected sociodemographic data, PA levels of participants before and after the SASEM 5k run race, as well as the PALMS. PALMS is a valid and reliable assessment tool for PA motives, consisting of 40 items, with eight subscales: competition/ego, appearance, others' expectations, affiliation, physical condition, psychological condition, mastery, and enjoyment. All participants provided electronic consent, and participation in the study was voluntary and uncompensated. Data were analyzed using the Statistical Package for the Social Sciences SPSS application.Results: One hundred and twenty-nine individuals participated in the survey (response rate: 38.5%). The final analysis included responses from HCWs only, which represented 68.2% of all responses (88). HCWs were divided into the following: physicians (55.7%), nurses (19.3%), emergency medical technicians (EMTs) (3.4%), other specialties (13.6%), and those retired from the medical field (8%). Participants working in emergency departments contributed 61.4% of the 88 responses. In the context of PA level in relation to (SASEM 5k), 59% increased their PA to be >10,000 steps, and 34% to be >300 min per week, in contrast to the time before the race (50% and 21%, respectively). Physical (90%) and psychological (79.6%) conditions were the most contributing factors to motivate PA. The EMTs (100%) and nurses (82.4%) were motivated by competition/ego. The appearance was not an important motivator for PA among the participants (86.4%). Physical and psychological conditions, others' expectations, and competition/ego were the motivators for emergency medicine (90.7%, 79.6%, 88.9%, and 63%, respectively).Conclusion: SASEM 5k run race successfully contributed to influencing the PA level. This might reflect the impact of a run race in conjunction with health-care events. We recommend organizing running races more frequently around various events to encourage people to maintain and increase PA throughout the year.

Sprinting with prosthetic versus biological legs: insight from experimental data.

Running-prostheses have enabled exceptional athletes with bilateral leg amputations to surpass Olympic 400 m athletics qualifying standards. Due to the world-class performances and relatively fast race finishes of these athletes, many people assume that running-prostheses provide users an unfair advantage over biologically legged competitors during long sprint races. These assumptions have led athletics governing bodies to prohibit the use of running-prostheses in sanctioned non-amputee (NA) competitions, such as at the Olympics. However, here we show that no athlete with bilateral leg amputations using running-prostheses, including the fastest such athlete, exhibits a single 400 m running performance metric that is better than those achieved by NA athletes. Specifically, the best experimentally measured maximum running velocity and sprint endurance profile of athletes with prosthetic legs are similar to, but not better than those of NA athletes. Further, the best experimentally measured initial race acceleration (from 0 to 20 m), maximum velocity around curves, and velocity at aerobic capacity of athletes with prosthetic legs were 40%, 1–3% and 19% slower compared to NA athletes, respectively. Therefore, based on these 400 m performance metrics, use of prosthetic legs during 400 m running races is not unequivocally advantageous compared to the use of biological legs.

Fatigue Measured in Dynamic Versus Isometric Modes After Trail Running Races of Various Distances

Fatigue has previously been investigated in trail running by comparing maximal isometric force before and after the race. Isometric contractions may not entirely reflect fatigue-induced changes, and therefore dynamic evaluation is warranted. The aim of the present study was to compare the magnitude of the decrement of maximal isometric force versus maximal power, force, and velocity after trail running races ranging from 40 to 170km. Nineteen trail runners completed races shorter than 60km, and 21 runners completed races longer than 100km. Isometric maximal voluntary contractions (IMVCs) of knee extensors and plantar flexors and maximal 7-second sprints on a cycle ergometer were performed before and after the event. Maximal power output (Pmax; -14% [11%], P < .001), theoretical maximum force (F0; -11% [14%], P < .001), and theoretical maximum velocity (-3% [8%], P = .037) decreased significantly after both races. All dynamic parameters but theoretical maximum velocity decreased more after races longer than 100km than races shorter than 60km (P < .05). Although the changes in IMVCs were significantly correlated (P < .05) with the changes in F0 and Pmax, reductions in IMVCs for knee extensors (-29% [16%], P < .001) and plantar flexors (-26% [13%], P < .001) were larger (P < .001) than the reduction in Pmax and F0. After a trail running race, reductions in isometric versus dynamic forces were correlated, yet they are not interchangeable because the losses in isometric force were 2 to 3 times greater than the reductions in Pmax and F0. This study also shows that the effect of race distance on fatigue measured in isometric mode is true when measured in dynamic mode.