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Applying magnetic resonance methods to measure the metabolic response in exercise poses a technical challenge because the construction of the ergometer must use non-magnetic components and assess work in the confined space of a magnet bore. The present report details the fabrication of a non-magnetic ergometer for use in a standard Siemens 3 Tesla (T) spectrometer. Using the ergometer, researchers can measure the 31P magnetic resonance spectroscopy (MRS) signals during leg muscle exercise and exercise recovery. In particular, the phosphocreatine (PCr) kinetics during exercise recovery reflects the mitochondrial oxidative capacity, and the inorganic phosphate (Pi) signal tracks the cellular pH. The ergometer allows for the use of a personalized, and variable load that normalizes the work for all study participants regardless of their leg strength. The ergometer then enables a standardized MRS comparison of leg muscle bioenergetics.

In recent years, different companies have developed devices that estimate "running power". The main objective of this paper is to evaluate the effect of running speed on aerobic and running powers measured using force plates and by different devices. The second objective is to evaluate the relationship between aerobic power and running powers measured using force plates and by different devices. We enrolled 11 subjects in the study, they performed 5-min running trials at 2.22, 2.78, 3.33, 3.89 and 4.44 m/s respectively on a force-measuring treadmill while we collected metabolic data. We calculated running power as the dot product of ground reaction force and velocity of the centre of mass and compared it to the running power estimates of three devices: Skillrun (Technogym), Stryd Summit Powermeter (Stryd) and Garmin HRM-Run (Garmin). We found statistically significant linear correlations with running powers measured by all devices and running speed. Although absolute running power measurements were different among devices, an increase of 1 m/s in running speed translated to an increase of 0.944 W/kg in running power (p < 0.001). We found statistically significant linear correlations with running powers measured by all devices and aerobic power, in particular: as aerobic power increases by 1 W/kg, running power increases by 0.218 W/kg for all devices (p < 0.001). For level treadmill running, across speeds, running power measured by commercially available devices reflects force-based measurements and it can be a valuable metric, providing quasi real-time feedback during training sessions and competitions. Highlights We evaluated the effect of running speed on aerobic and running powers measured using force plates and by different devices. We also compared the relationship between aerobic power and running powers measured using force plates and by different devices. We found statistically significant linear correlations with running powers measured by all devices and aerobic power, in particular: as aerobic power increases by 1 W/kg, running power increases by 0.218 W/kg for all devices. For level treadmill running, across speeds, running power measured by commercially available devices reflects force-based measurements and it can be a valuable metric, providing quasi real-time feedback during training sessions and competitions. [ABSTRACT FROM AUTHOR]

Purpose: To investigate changes in running mechanics during a 6-h running race. Methods: Twelve ultraendurance runners (age 41.9 ± 5.8 y, body mass 68.3 ± 12.6 kg, height 1.72 ± 0.09 m) were asked to run as many 874-m flat loops as possible in 6 h. Running speed, contact time (tc), and aerial time (ta) were measured in the first lap and every 30 ± 2 min during the race. Peak vertical ground-reaction force (Fmax), stride length (SL), vertical downward displacement of the center of mass (Δz), leg-length change (ΔL), vertical stiffness (kvert), and leg stiffness (kleg) were then estimated. Results: Mean distance covered by the athletes during the race was 62.9 ± 7.9 km. Compared with the 1st lap, running speed decreased significantly from 4 h 30 min onward (mean -5.6% ± 0.3%, P < .05), while tc increased after 4 h 30 min of running, reaching the maximum difference after 5 h 30 min (+6.1%, P = .015). Conversely, kvert decreased after 4 h, reaching the lowest value after 5 h 30 min (-6.5%, P = .008); ta and Fmax decreased after 4 h 30 min through to the end of the race (mean -29.2% and -5.1%, respectively, P < .05). Finally, SL decreased significantly (-5.1%, P = .010) during the last hour of the race. Conclusions: Most changes occurred after 4 h continuous self-paced running, suggesting a possible time threshold that could affect performance regardless of absolute running speed. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effects of an uphill marathon (43 km, 3063-m elevation gain) on running mechanics and neuromus-cular fatigue in lower-limb muscles. Methods: Maximal mechanical power of lower limbs (MMP), temporal tensiomyographic (TMG) parameters, and muscle-belly displacement (Dm) were determined in the vastus lateralis muscle before and after the competition in 18 runners (age 42.8 ± 9.9 y, body mass 70.1 ± 7.3 kg, maximal oxygen uptake 55.5 ± 7.5 mL ⋅ kg-1 ⋅ min-1). Contact (tc) and aerial (ta) times, step frequency (f), and running velocity (v) were measured at 3, 14, and 30 km and after the finish line (POST). Peak vertical ground-reaction force (Fmax), vertical displacement of the center of mass (Δz), leg-length change (ΔL), and vertical (kvert) and leg (kleg) stiffness were calculated. Results: MMP was inversely related with race time (r = -.56, P = .016), tc (r = -.61, P = .008), and Δz (r = -.57, P = .012) and directly related with Fmax (r = .59, P = .010), ta (r = .48, P = .040), and kvert (r = .51, P = .027). In the fastest subgroup (n = 9) the following parameters were lower in POST (P < .05) than at km 3: ta (-14.1% ± 17.8%), Fmax (-6.2% ± 6.4%), kvert (-17.5% ± 17.2%), and kleg (-11.4% ± 10.9%). The slowest subgroup (n = 9) showed changes (P < .05) at km 30 and POST in Fmax (-5.5% ± 4.9% and -5.3% ± 4.1%), ta (-20.5% ± 16.2% and -21.5% ± 14.4%), tc (5.5% ± 7.5% and 3.2% ± 5.2%), kvert (-14.0% ± 12.8% and-11.8% ± 10.0%), and kleg (-8.9% ± 11.5% and-11.9% ± 12%). TMG temporal parameters decreased in all runners (-27.35% ± 18.0%, P < .001), while Dm increased (24.0% ± 35.0%, P = .005), showing lower-limb stiffness and higher muscle sensibility to the electrical stimulus. Conclusions: Greater MMP was related with smaller changes in running mechanics induced by fatigue. Thus, lower-limb power training could improve running performance in uphill marathons. [ABSTRACT FROM AUTHOR]

PURPOSE: To investigate the effects of an extreme uphill marathon on the mechanical parameters that are likely to affect the energy cost of running (Cr). METHODS: Eleven runners (27-59 y) participated in the Etna SuperMarathon (43 km, 0-3063 m above sea level). Anthropometric characteristics, maximal explosive power of the lower limb (Pmax), and maximal oxygen uptake were determined before the competition. In addition, before and immediately after the race, Cr, contact (tc) and aerial (ta) times, step frequency (f), and running velocity were measured at constant self-selected speed. Then, peak vertical ground-reaction force (Fmax), vertical downward displacement of the center of mass (Δz), leg-length change (ΔL), and vertical (kvert) and leg (kleg) stiffness were calculated. RESULTS: A direct relationship between Cr, measured before the race, and race time was shown (r = .61, P < .001). Cr increased significantly at the end of the race by 8.7%. Immediately after the race, the subjects showed significantly lower ta (-58.6%), f (-11.3%), Fmax (-17.6%), kvert (-45.6%), and kleg (-42.3%) and higher tc (+28.6%), Δz (+52.9%), and ΔL (+44.5%) than before the race. The increase of Cr was associated with a decrement in Fmax (r = -.45), kvert (r = -.44), and kleg (r = -.51). Finally, an inverse relationship between Pmax measured before the race and ΔCr during race was found (r = -.52). CONCLUSIONS: Lower Cr was related with better performance, and athletes characterized by the greater Pmax showed lower increases in Cr during the race. This suggests that specific power training of the lower limbs may lead to better performance in ultraendurance running competition. [ABSTRACT FROM AUTHOR]

In the 2012 Paralympic 100 in and 200 m finals, 86% of athletes with a unilateral amputation placed their unaffected leg on the front starting block. Can this preference be explained biomechanically? We measured the biomechanical effects of starting block configuration for seven nonamputee sprinters and nine athletes with a unilateral amputation. Each subject performed six starts, alternating between their usual and unusual starting block configurations. When sprinters with an amputation placed their unaffected leg on the front block, they developed 6% greater mean resultant combined force compared with the opposite configuration (1.38 ± 0.06 vs 1.30 ± 0.11 BW, P= .015). However, because of a more vertical push angle, horizontal acceleration performance was equivalent between starting block configurations. We then used force data from each sprinter with an amputation to calculate the hypothetical starting mechanics for a virtual nonamputee (two unaffected legs) and a virtual bilateral amputee (two affected legs). Accelerations of virtual bilateral amputees were 15% slower compared with athletes with a unilateral amputation, which in turn were 11% slower than virtual nonamputees. Our biomechanical data do not explain the starting block configuration preference but they do explain the starting performance differences observed between nonamputee athletes and those with leg amputations. [ABSTRACT FROM AUTHOR]

Eliud Kipchoge made two attempts to break the 2-hour marathon, in Monza and then Vienna. Here we analyse only the effects of course elevation profile and turn curvatures on his performances. We used publicly available data to determine the undulations in elevation and the radii of the curves on the course. With previously developed equations for the effects of velocity, slope, and curvature on oxygen uptake, we performed simulations to quantify how much the elevation changes and curves of the Vienna course affect a runner's oxygen uptake (at a fixed velocity) or velocity (at a fixed oxygen uptake). We estimate that, after the initial downhill benefit, the course led to an overall oxygen uptake penalty of only 0.03%. When compared to a perfectly level straight course, we estimate that the combined effects of the undulations and curves of the Vienna course incurred a penalty of just 1.37 seconds. Kipchoge ran 2:00:25 in Monza Italy. Comparison with the Monza course profile indicates a 46.2 second (1.09% oxygen uptake) advantage of Vienna's course while the fewer curves of Vienna contributed ~ 1 second. The Vienna course was very well-chosen because it minimized the negative effects of elevation changes and curves. Abbreviations: CoT: Oxygen cost of transport; C V ˙ O2: Curved rate of oxygen consumption; V ˙ O2: Rate of oxygen consumption; WA: World Athletics [ABSTRACT FROM AUTHOR]

Athletes in the 3,000 m steeplechase track and field event negotiate unmovable hurdles and waterjumps. Ground reaction forces (GRF) in the steeplechase were quantified to elucidate injury risks / mechanisms and to inform coaches. Five male and five female steeplechasers participated. GRF were measured during treadmill running, and using specially mounted force platforms, during hurdle and waterjump takeoffs and landings at 5.54 m/s (males) or 5.00 m/s (females). Results are presented as: male mean ± SD / female mean ± SD. Initial and active peaks of vertical GRF during treadmill running were 2.04 ± 0.72 / 2.25 ± 0.28 BW and 3.11 ± 0.27 / 2.98 ± 0.24 BW. Compared to treadmill running, peak vertical forces were greater (p < 0.001) for: hurdle takeoff (initial: 4.25 ± 0.86 / 3.78 ± 0.60 BW, active: 3.82 ± 0.20 / 3.74 ± 0.32 BW), hurdle landing (active: 4.41 ± 1.13 / 4.21 ± 0.21 BW), waterjump takeoff (initial: 4.32 ± 0.67 / 4.56 ± 0.54 BW, active: 4.00 ± 0.24 / 3.83 ± 0.31 BW), and waterjump landing (initial: 3.45 ± 0.34 / #3.78 ± 0.32 BW, active:5.40 ± 0.78 / #6.23 ± 0.74 BW); (#) indicates not statistically compared (n = 2). Based on horizontal impulse, athletes decelerated during takeoff steps and accelerated during landing steps of both hurdling and waterjumps. Vertical GRF peaks and video indicated rearfoot strikes on the treadmill but midfoot strikes during hurdle and waterjump landings. Potentially injurious GRF occur during the steeplechase, particularly during waterjump landings (up to 7.0 BW). [ABSTRACT FROM AUTHOR]

The correct affiliation is listed below: Department of Human Physiology, Gonzaga University, Spokane, WA, USA The original Article has been corrected. Correction to: I Scientific Reports i https://doi.org/10.1038/s41598-023-34346-x, published online 11 May 2023 The original version of this Article contained an error in Affiliation 2, which was incorrectly given as "Department of Human Physiology, Gonzaga University, Spokane, USA". [Extracted from the article]

The aim of this study was to investigate: (1) the role of , the fraction of (F) and the metabolic cost of transport (CoT) in determining performance during an ultra-endurance competition and (2) the effects of the race on several biomechanical and morphological parameters of the lower limbs that are likely to affect CoT. Eleven runners (aged 29-54 years) participated in an ultra-endurance competition consisting of three running stages of 25, 55 and 13 km on three consecutive days. Anthropometric characteristics, body composition, morphological properties of the gastrocnemius medialis, maximal explosive power of the lower limb and were determined before the competition. In addition, biomechanics of running and CoT were determined, before and immediately after each running stage. Performance was directly proportional to (r=0.77) and F (r=0.36), and inversely proportional to CoT (r=-0.30). Low CoT values were significantly related to high maximal power of the lower limbs (r=-0.74) and vertical stiffness (r=-0.65) and low footprint index (FPI, r=0.70), step frequency (r=0.62) and external work (r=0.60). About 50% of the increase in CoT during the stages of the competition was accounted for by changes in FPI, which represents a global evaluation of medio-lateral displacement of the foot during the whole stance phase, which in turn is associated with the myotendinous characteristics of the lower limb. Thus, lower CoT values were related to greater muscular power and lower FPI, suggesting that a better ankle stability is likely to achieve better performance in an ultra-endurance running competition.