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Purpose: Long-distance running performance has been reported to be associated with sprint performance in highly trained distance runners. Therefore, we hypothesized that sprint training could enhance distance running and sprint performance in long-distance runners. This study examined the effect of 6-week sprint training on long-distance running and sprint performance in highly trained distance runners. Methods: Nineteen college runners were divided into control (n = 8) and training (n = 11) groups. Participants in the training group performed 12 sprint training sessions in 6 weeks, while those in the control group performed 12 distance training sessions. Before and after the interventions, maximal oxygen uptake ( V ˙ O 2 max), O2 cost during submaximal running (290 m·min−1 and 310 m·min−1 of running velocity), and time to exhaustion (starting at 290 m·min–1 and increased 10 m·min–1 every minute) were assessed on a treadmill. Additionally, the 100-m and 400-m sprinting times and 3000-m running time were determined on an all-weather track. Results: In the control group, no measurements significantly changed after the intervention. In the training group, the time to exhaustion, 100-m and 400-m sprinting times, and 3000-m running time improved significantly, while V ˙ O 2 max and O2 cost did not change. Conclusions: These results showed that 6-week sprint training improved both sprint and long-distance running performance in highly trained distance runners without a change in aerobic capacity. Improvement in the time to exhaustion without a change in V ˙ O 2 max suggests that the enhancement of long-distance running performance could be attributable to improved anaerobic capacity. [ABSTRACT FROM AUTHOR]

This study investigated the coactivation of plantar flexor and dorsiflexor muscles and oxygen uptake during running with forefoot and rearfoot strikes at 15 and 19 km/h. We included 16 male runners in this study. The participants ran each foot strike pattern for 5 min at 15 and 19 km/h on a treadmill. During the running, respiratory gas exchange data and surface electromyographic (EMG) activity of the medial gastrocnemius (MG), lateral gastrocnemius (LG), soleus, and tibialis anterior muscles of the right lower limb were continuously recorded. The indices of oxygen uptake, energy expenditure (EE), and muscle activation were calculated during the last 2 min in each condition. During the stance phase of running at 15 and 19 km/h, activation of the tibialis anterior and MG muscles was lower and higher, respectively, with forefoot strike than with rearfoot strike. The foot strike pattern did not influence the oxygen uptake. These results suggest that the foot strike pattern has no clear effect on the oxygen uptake when running at 15 and 19 km/h. However, forefoot strike leads to plantar flexion dominance during co‐contraction of the tibialis anterior and MG muscles, which are an antagonist and agonist for plantar flexion, respectively, during the stance phase. [ABSTRACT FROM AUTHOR]

The metabolic cost of locomotion is a key factor in walking and running performance. It has been studied by analysing the activation and co-activation of the muscles of the lower limbs. However, these measures do not comprehensively address muscle mechanics, in contrast to approaches using muscle moments and co-contraction. What is the effect of speed and type of locomotion on muscle moments and co-contraction, and their relationship with metabolic cost during walking and running? Eleven recreational athletes (60.5 ± 7.1 kg; 169.0 ± 6.6 cm; 23.6 ± 3.3 years) walked and ran on a treadmill at different speeds, including a similar speed of 1.75 m.s−1. Metabolic cost was estimated from gas exchange measurements. Muscle moments and co-contraction of ankle and knee flexors and extensors during the stance and swing phases were estimated using an electromyographic-driven model. Both the slowest and fastest walking speeds had significantly higher metabolic costs than intermediate ones (p < 0.05). The metabolic cost of walking was correlated with plantarflexors moment during swing phase (r = 0.62 at 0.5 m.s−1, r = 0.67 at 1,25 m.s−1), dorsiflexors moment during stance phase (r = 0.65 at 1.25 m.s−1, r = 0.67 at 1.5 and 1.75 m.s−1), and ankle co-contraction during the stance phase (r = 0.63 at 1.25 and 1.75 m.s−1). The metabolic cost of running at 3.25 m.s−1 during the swing phase was correlated with the dorsiflexors moment (r = 0.63), plantarflexors moment (r = 0.61) and ankle co-contraction (r = 0.60). Fluctuations in metabolic cost of walking and running could be explained, at least in part, by increased ankle antagonist moments and co-contraction. • EMG-driven model was used to estimate the muscle moments and co-contractions. • Increased antagonist muscle moments partly drive the increased metabolic cost. • Metabolic cost is more dependent on motor strategies at the ankle than at the knee. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate the effect of the MC and endogenous sex hormone concentrations on performance-determining variables in three distinctMC phases in endurance-trained females. Methods: Twenty-one eumenorrheic trained/highly trained endurance athletes completed a standardized test battery during the early follicular phase (EFP), ovulatory phase (OP), and midluteal phase (MLP) for either one (n = 7) or two test cycles (n = 14). MC phases were determined using calendar-based counting, urinary ovulation testing, and verified with serum hormone analysis. MCs were retrospectively classified as eumenorrheic or disturbed. Disturbed MCs were excluded from analysis. The test battery consisted of 4-6 x 5-min submaximal stages with stepwise speed increases, a 30-s all-out double-poling ski ergometer test, and a maximal incremental treadmill running test. Results: At a group level, there was no effect of MC phase or the serum concentrations of estrogen and progesterone on peak oxygen uptake (...), oxygen uptake at 4 mmol⋅L-1 blood lactate concentration, time to exhaustion, running economy, or mean 30-s power output (MPO30s). Serum testosterone concentration was positively associated with MPO30s (P = 0.016). Changes in ... from EFP to MLP were inconsistent between individuals and across cycles. Conclusions: None of the measured performance-determining variables were influenced by MC phase or serumestrogen or progesterone concentrations. Although some individual patterns could be observed, there was no indication that any single MC phase is consistently associated with improved or impaired ... on a group level. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of the present study was to compare the acute effects of different rest period durations after general warm-up (GWU) and dynamic stretching (DS) on endurance running performance. Methods: Eight male runners performed endurance running performance tests after three types of intervention. The interventions were as follows: (1) GWU + 5 min Rest, (2) GWU + DS + 5 min Rest, and (3) GWU + DS + 10 min Rest. The GWU consisted of running exercises on a treadmill at a velocity equivalent to 70% of maximum oxygen uptake (V̇O2max) for 15 min. The DS consisted of performing 10 repetitions as quickly as possible for the five muscle groups of the lower extremities. Endurance running performance was measured by time to exhaustion (TTE) during running on the treadmill at a velocity equivalent to 90% V̇O2max. Results: TTE (884.5 ± 244.9 s) after GWU + DS + 10 min Rest intervention was significantly (p < 0.05) longer than that (719.8 ± 227.9 s) after GWU + 5 min Rest. TTE (734.5 ± 274.2 s) after GWU + DS + 5 min Rest intervention was not significantly different than that of the other two interventions. Conclusion: The results demonstrated that the endurance running performance at the velocity equivalent to 90% V̇O2max was enhanced by GWU + DS + 10 min Rest, but not GWU + DS + 5 min Rest. We recommend that runners rest for approximately 10 min after GWU + DS to enhance endurance running performance. [ABSTRACT FROM AUTHOR]

The bending stiffness of footwear impacts running efficiency and lower-limb work redistribution. However, studies integrating both aspects are scarce. This study aimed to examine the impact of footwear stiffness on lower-limb biomechanics, joint work, and overall metabolic efficiency. This study was performed on 12 male recreational runners to complete an experimental protocol while wearing two different running shoes with varying degrees of longitudinal bending stiffness. Paired-sample t tests were applied in this research. The stiffer footwear decreased the range of motion (ROM), angular velocity, negative and positive work of the metatarsophalangeal (MTP) joint, and ROM of the ankle joint. The running economy significantly improved with the stiffer footwear. However, no significant difference was observed in the joint work of other lower limbs. Shoes with increased bending stiffness significantly reduced the MTP joint ROM and angular velocity, thereby reducing negative power and work at the MTP joint and improving running economy for runners. This study provided relevant information for shoe designers, developers, and scientists conducting research on footwear midsole structures and designs. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate the effects of a 7-d high-intensity interval training shock microcycle (HIIT-SM) with or without additional low-intensity training (LIT) on aerobic fitness and endurance performance compared with a control group (CG). Methods: Thirty-three endurance-trained athletes (7 women, 26 men, mean ± SD: age, 30.2 ± 6.9 yr;maximal oxygen uptake (VO2max), 59.8 ± 4.9 mL·min-1·kg-1) performed exercise testing at T1 and were randomly assigned to one of three groups: i) HSM, 10 running-based HIIT sessions (5 × 4 min at 90%-95% maximal heart rate) over 7 d; ii)HSM+ LIT, equal toHSMwith additional 30 min of LIT after each HIIT; iii) CG, regular training. Exercise testing was repeated 3 d (T2), 7 d (T3), and 14 d (T4) after the intervention. A 5-km time trial (TT5km) was performed 3-4 d before T1 and 10-11 d after the intervention. Data were analyzed by two-way repeated-measures ANOVA. Results: No interaction effect was found for VO2max (P = 0.170, pη² = 0.09), peak power output (P = 0.734, pη² = 0.04), and work economy (P = 0.804, pη² = 0.03). There was an interaction for velocity at lactate threshold (P = 0.006, pη² = 0.18) with increased velocity in HSM at T2 (3.2%, P = 0.030), T3 (4%, P = 0.006), T4 (4%, P = 0.003), as well as in HSM + LIT for T2 (3.2%, P = 0.011), whereas CG showed no change. There was an interaction for TT5km (P = 0.044, pη² = 0.19), with HSM improving 2.7% (P = 0.003) and HSM + LIT 2.3% (P = 0.010), whereas CG was, on average, -0.3% (P = 0.821) slower. Conclusions: HIIT-SM with or without additional LIT has negligible effects on VO2max but improves other key endurance variables in endurance-trained athletes. No superiority of either intervention group was demonstrated. Therefore, additional LIT during HIIT-SM is not beneficial. [ABSTRACT FROM AUTHOR]

Purpose: We evaluated (1) whether participating in middle- and long-distance running races augments muscle soreness, oxygen cost, respiration, and exercise exertion during subsequent running, and (2) if post-race menthol application alleviates these responses in long-distance runners. Methods: Eleven long-distance runners completed a 1500-m race on day 1 and a 3000-m race on day 2. On day 3 (post-race day), either a 4% menthol solution (Post-race menthol) or a placebo solution (Post-race placebo) serving as a vehicle control, was applied to their lower leg skin, and their perceptual and physiological responses were evaluated. The identical assessment with the placebo solution was also conducted without race participation (No-race placebo). Results: The integrated muscle soreness index increased in the Post-race placebo compared to the No-race placebo (P < 0.001), but this response was absent in the Post-race menthol (P = 0.058). Oxygen uptake during treadmill running tended to be higher (4.3%) in the Post-race placebo vs. No-race placebo (P = 0.074). Oxygen uptake was 5.4% lower in the Post-race menthol compared to the Post-race placebo (P = 0.018). Minute ventilation during treadmill running was 6.7–7.6% higher in the Post-race placebo compared to No-race placebo, whereas it was 6.6–9.0% lower in the Post-race menthol vs. Post-race placebo (all P ≤ 0.001). The rate of perceived exertion was 7.0% lower in the Post-race menthol vs. Post-race placebo (P = 0.007). Conclusions: Middle- and long-distance races can subsequently elevate muscle soreness and induce respiratory and metabolic stress, but post-race menthol application to the lower legs can mitigate these responses and reduce exercise exertion in long-distance runners. [ABSTRACT FROM AUTHOR]

Muscle-tendon unit (MTU) morphology and physiology are likely major determinants of locomotor performance and therefore Darwinian fitness. However, the relationships between underlying traits, performance, and fitness are complicated by phenomena such as coadaptation, multiple solutions, and trade-offs. Here, we leverage a long-running artificial selection experiment in which mice have been bred for high levels of voluntary running to explore MTU adaptation, as well as the role of coadaptation, multiple solutions, and trade-offs, in the evolution of endurance running. We compared the morphological and contractile properties of the triceps surae complex, a major locomotor MTU, in four replicate selected lines to those of the triceps surae complex in four replicate control lines. All selected lines have lighter and shorter muscles, longer tendons, and faster muscle twitch times than all control lines. Absolute and normalized maximum shortening velocities and contractile endurance vary across selected lines. Selected lines have similar or lower absolute velocities and higher endurance than control lines. However, normalized shortening velocities are both higher and lower in selected lines than in control lines. These findings potentially show an interesting coadaptation between muscle and tendon morphology and muscle physiology, highlight multiple solutions for increasing endurance running performance, demonstrate that a trade-off between muscle speed and endurance can arise in response to selection, and suggest that a novel physiology may sometimes allow this trade-off to be circumvented. [ABSTRACT FROM AUTHOR]

Copyright of Retos: Nuevas Perspectivas de Educación Física, Deporte y Recreación is the property of Federacion Espanola de Asociaciones de Docentes de Educacion Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: In recent years, as the popularity of long-distance fitness running continues to rise, more research progress has been made on related scientific issues. Among them, the landing pattern of long-distance running is an important biomechanical research hotspot at the level of running technique. OBJECTIVE: Using CiteSpace to visualize and analyze the relevant literature, the article sorts through the last decade’s literature on the subject to identify the current state, hot spots, and trends in the footprint as well as to further discuss the main research hotspots of the foot strike pattern from a biomechanical perspective. METHODS: “Foot strike pattern,” “Rearfoot strike,” “non-Rearfoot strike,” “Forefoot strike” and “Midfoot strike” were used as keywords to search the Web of Science Core Collection database. RESULTS AND CONCLUSION: A total of 896 relevant papers were finally included. The number of articles published in a year showed an overall upward trend. The top three countries in terms of the number of publications were the United States, China and the United Kingdom; the top three institutions were Harvard University, Shanghai University of Sports and the University of Massachusetts; and the top three authors were Davis Irene S, Hamill Joseph and Fu Weijie. The keywords “barefoot running, runner, injury, footing pattern, kinesiology” appear more frequently, and the keyword clusters include “energy cost, loading rate, footing pattern, risk factors, gait analysis”, and the relevant research still continues to be hot to this day. After analyzing the above data in detail, we found that the overall research intensity of foot strike pattern has remained stable in recent years, and the hotspot mainly focuses on the biomechanical research of foot strike pattern; the trend of this kind of research focuses on the influence and adaptability of different strike patterns (forefoot strike and rearfoot strike) on long-distance runners (barefoot, shoes, distance, speed, injury risk, running economy and energy consumption, etc.). Therefore, there is no “standardized optimal landing,” but there may be “individualized optimal landings.” It is suggested that researchers should select the optimal landing pattern and running technique strategy according to their own habitual way, movement pattern characteristics, exercise level and task attributes. [ABSTRACT FROM AUTHOR]

Purpose: Previous research has shown that maximal oxygen uptake (VO2max) significantly influences performance in trail-running races up to 120 km but not beyond. Similarly, the influence of running economy on performance in ultratrail remains unclear. The aim of our study was, therefore, to determine the physiological predictors of performance in a 166-km trail-running race. Methods: Thirty-three experienced trail runners visited the laboratory 4 to 8 weeks before the race to undergo physiological testing including an incremental treadmill test and strength assessments. Correlations and regression analyses were used to determine the physiological variables related to performance. Results: Average finishing time was 37:33 (5:52) hours. Performance correlated significantly with VO2max (r = −.724, P <.001), velocity at VO2max (r = −.813, P <.001), lactate turn point expressed as percentage of VO2max (r = −.510, P =.018), cost of running (r = −.560, P =.008), and body fat percentage (r =.527, P =.012) but was not related to isometric strength. Regression analysis showed that velocity at VO2max predicted 65% of the variability in performance (P <.001), while a model combining VO2max and cost of running combined predicted 62% of the variability (P =.008). Conclusion: This is the first study to show that VO2max and velocity at VO2max are significant predictors of performance in a 166-km trail-running race. This suggests that ultratrail runners should focus on the development of these 2 qualities to optimize their race performance. [ABSTRACT FROM AUTHOR]

Purpose: Carbon plates have been used to increase running shoes' longitudinal bending stiffness (LBS), leading to reductions in the energy cost of level running (Cr). However, whether or not this is true during uphill (UH) running remains unknown. The aim of our study was to identify the effect of LBS on Cr during UH running. Methods: Twenty well-trained male runners participated in this study. Cr was determined using gas exchange during nine 4-minute bouts performed using 3 different LBS shoe conditions at 2.22 and 4.44 m/s on level and 2.22 m/s UH (gradient: + 15%) running. All variables were compared using 2-way analyses of variance (LBS × speed/grade effects). Results: There was no significant effect of LBS (F = 2.04; P =.14, η p 2 =.11) and no significant LBS × grade interaction (F = 0.31; P =.87, η p 2 =.02). Results were characterized by a very large interindividual variability in response to LBS changes. Conclusions: The current study contributes to a growing body of literature reporting no effect of LBS on Cr during level and UH running. Yet, the very large interindividual differences in response to changes in LBS suggest that increasing shoe LBS may be beneficial for some runners. [ABSTRACT FROM AUTHOR]

This study aimed to explore the effect of two similar commercialized advanced footwear technology models differing mainly in their plate geometry (i.e., low and high curvature plate) on the running energetic cost in both non-fatigued and fatigued states. It also sought to determine their impacts on 3000-m performance. Twelve highly trained male athletes performed four 5-min trials (two advanced technology models, two trials). In each experimental session, athletes completed a 3000-m trial which was followed by a 5-min trial to test the running energetic cost when fatigued. Athletes exhibited a lower running energetic cost when wearing the low curvature plate in a non-fatigued state (P = 0.034; − 1.13 [− 1.92 to − 0.11] %), which persisted with better performance in the 3000-m trial (P = 0.017; − 0.42 [− 0.74 to − 0.09] %). However, in a fatigued state, non-significant differences were reported (P = 0.207). The low curvature plate seems to be more effective than the high curvature plate when running at low intensity in a fresh state as well as in a maximal high-intensity effort. However, non-significant differences between plate geometries were observed when fatigue was increased. [ABSTRACT FROM AUTHOR]

Women perform exercise in sports bras to limit breast motion. However, as the breasts become restricted, respiratory function may become compromised. Purpose: We set out to understand how underband tightness or pressure of a sports bra relates to respiratory function and the mechanical work of breathing (...B) during exercise. Our secondary purpose was to quantify the effects of underband pressure on ...O2 during submaximal running. Methods: Nine highly trained female runners with normal pulmonary function completed maximal and submaximal running in three levels of underband restriction: loose, self-selected, and tight. Results: During maximal exercise, we observed a significantly greater ...B during the tight condition (350 ± 78 J⋅min-1) compared with the loose condition (301 ± 78 J⋅min-1; P < 0.05), and a 5% increase in minute ventilation (...E) during the tight condition compared with the loose condition (P < 0.05). The pattern of breathing also differed between the two conditions; the greater maximal ...E during the tight condition was achieved by a higher breathing frequency (57 ± 6 vs. 52 ± 7 breaths⋅min-1; P < 0.05), despite tidal volume being significantly lower in the tight condition compared with the loose condition (1.97 ± 0.20 vs. 2.05 ± 0.23 L; P < 0.05). During steady-state submaximal running, ...O2 increased 1.3 ± 1.1% (range: -0.3 to 3.2%, P < 0.05) in the tight condition compared with the loose condition. Conclusions: Respiratory function may become compromised by the pressure exerted by the underband of a sports bra when women self-select their bra size. In the current study, loosening the underband pressure resulted in a decreased work of breathing, changed the ventilatory breathing pattern to deeper, less frequent breaths, and decreased submaximal oxygen uptake (improved running economy). Our findings suggest sports bra underbands can impair breathing mechanics during exercise and influence whole-body metabolic rate. [ABSTRACT FROM AUTHOR]

Introduction/Purpose: Shoe longitudinal bending stiffness (LBS) is often considered to influence running economy (RE) and thus, running performance. However, previous results are mixed and LBS levels have not been studied in advanced footwear technology (AFT). The purpose of this study was to evaluate the effects of increased LBS from curved carbon fiber plates embedded within an AFT midsole compared to a traditional running shoe on RE and spatiotemporal parameters. Methods: Twenty‐one male trained runners completed three times 4 min at 13 km/h with two experimental shoe models with a curved carbon fiber plate embedded in an AFT midsole with different LBS values (Stiff: 35.5 N/mm and Stiffest: 43.1 N/mm), and a Control condition (no carbon fiber plate: 20.1 N/mm). We measured energy cost of running (W/kg) and spatiotemporal parameters in one visit. Results: RE improved for the Stiff shoe condition (15.71 ± 0.95 W/kg; p < 0.001; n2 = 0.374) compared to the Control condition (16.13 ± 1.08 W/kg; 2.56%) and Stiffest condition (16.03 ± 1.19 W/kg; 1.98%). However, we found no significant differences between the Stiffest and Control conditions. Moreover, there were no spatiotemporal differences between shoe conditions. Conclusion: Changes in LBS in AFT influences RE suggesting that moderately stiff shoes have the most effective LBS to improve RE in AFT compared to very stiff shoes and traditional, flexible shoe conditions while running at 13 km/h. [ABSTRACT FROM AUTHOR]

The enhancement of midsole compressive energy return is associated with improved running economy. Traditional midsole materials such as ethylene vinyl acetate (EVA), thermoplastic polyurethane (TPU), and polyether block amide (PEBA) foams typically exhibit hardening force-displacement characteristics. On the other hand, a midsole with softening properties, which can be achieved through compliant constant force mechanisms (CFMs), can provide significant benefits in terms of energy storage and return. This study presents the development of such a midsole, incorporating 3D printed TPU CFM designs derived through structural optimization. The mechanical properties under cyclic loading were evaluated and compared with those of commercially available running shoes with state-of-the-art PEBA foam midsoles, specifically the Nike ZoomX Vaporfly Next% 2 (NVP). Our custom midsole demonstrated promising mechanical performance. At similar deformation levels, the new design increased energy storage by 58.1% and energy return by 47.0%, while reducing the peak compressive force by 24.3%. As per our understanding, this is the first study to prove that the inclusion of CFMs in the structural design of 3D printed midsoles can significantly enhance energy return. [ABSTRACT FROM AUTHOR]

We sought to assess the effects of repeated cold-water immersions (CWI) on respiratory, metabolic, and sympathoadrenal responses to graded exercise in hypoxia. Sixteen (2 female) participants (age: 21.2 ± 1.3 years; body fat: 12.3 ± 7.7%; body surface area 1.87 ± 0.16 m2, VO2peak: 48.7 ± 7.9 mL/kg/min) underwent 6 CWI in 12.0 ± 1.2 °C. Each CWI was 5 min, twice daily, separated by ≥4 h, for three consecutive days, during which metabolic data were collected. The day before and after the repeated CWI intervention, participants ran in normobaric hypoxia (FIO2 = 0.135) for 4 min at 25%, 40%, 60%, and 75% of their sea level peak oxygen consumption (VO2peak). CWI had no effect on VO2 (p > 0.05), but reduced the VE (CWI #1: 27.1 ± 17.8 versus CWI #6: 19.9 ± 12.1 L/min) (p < 0.01), VT (CWI #1: 1.3 ± 0.4 vs CWI #6: 1.1 ± 0.4 L) (p < 0.01), and VE:VO2 (CWI #1: 53.5 ± 24.1 vs CWI #6: 41.6 ± 20.5) (p < 0.01) during subsequent CWI. Further, post exercise plasma epinephrine was lower after CWI compared to before (103.3 ± 43.1; 73.4 ± 34.6 pg/mL) (p = 0.03), with no change in pre-exercising values (75.4 ± 30.7; 72.5 ± 25.9 pg/mL). While these changes were noteworthy, it is important to acknowledge there were no changes in pulmonary (VE, VT, and VE:VO2) or metabolic (VO2, SmO2, and SpO2) variables across multiple hypoxic exercise workloads following repeated CWI. CWI habituated participants to cold water, but this did not lead to adaptations during exercise in normobaric hypoxia. [ABSTRACT FROM AUTHOR]

During running, the mechanical energy of the centre of mass of the body (COM) oscillates throughout the step like a spring-mass system, where part of its mechanical energy is stored during negative phases to be released during the following positive phases. This storage-release of energy improves muscle-tendon efficiency, which is related to lower-limb stiffness. This study explores the effect of sports background on the bouncing mechanism, by examining differences in stiffness and step spatiotemporal parameters between swimmers and football athletes. All athletes performed three consecutive running bouts on an instrumented treadmill at three different speeds (3.9, 4.4 and 5.0 m·s−1). The ground reaction forces were recorded. Vertical stiffness and step spatiotemporal parameters were analysed and compared using a two-way ANOVA. Vertical stiffness of football players was on average 21.0 ± 1.1% higher than swimmers. The modification of step spatiotemporal parameters also suggests a more elastic rebound by increasing the stretch of tendons relative to muscle within muscle–tendon units in football players. Compared to swimmers, they (1) decrease the effective contact time by 9.7 ± 2.4% and (2) decrease the duration of the push by 15.0 ± 6.4%, suggesting that background training adaptations influence spring-mass behaviour during running. [ABSTRACT FROM AUTHOR]

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract This study investigated the coactivation of plantar flexor and dorsiflexor muscles and oxygen uptake during running with forefoot and rearfoot strikes at 15 and 19 km/h. We included 16 male runners in this study. The participants ran each foot strike pattern for 5 min at 15 and 19 km/h on a treadmill. During the running, respiratory gas exchange data and surface electromyographic (EMG) activity of the medial gastrocnemius (MG), lateral gastrocnemius (LG), soleus, and tibialis anterior muscles of the right lower limb were continuously recorded. The indices of oxygen uptake, energy expenditure (EE), and muscle activation were calculated during the last 2 min in each condition. During the stance phase of running at 15 and 19 km/h, activation of the tibialis anterior and MG muscles was lower and higher, respectively, with forefoot strike than with rearfoot strike. The foot strike pattern did not influence the oxygen uptake. These results suggest that the foot strike pattern has no clear effect on the oxygen uptake when running at 15 and 19 km/h. However, forefoot strike leads to plantar flexion dominance during co‐contraction of the tibialis anterior and MG muscles, which are an antagonist and agonist for plantar flexion, respectively, during the stance phase.

When will women run a sub-4-minute mile? The answer seems to be a distant future given how women's progress has plateaued in the mile, or its better studied metric placeholder, the 1500 m. When commonly accepted energetics principles of running, along with useful field validation equations of the same, are applied to probe the physiology underpinning the 10 all-time best women's mile performances, insights gained may help explain the present 12.34-second shortfall. Insights also afford estimates of how realistic improvements in the metabolic cost of running could shrink the difference and bring the women's world record closer to the fabled 4-minute mark. As with men in the early 1950s, this might stir greater interest, excitement, participation, and depth in the women's mile, the present absence of which likely contributes to more pessimistic mathematical modeling forecasts. The purpose of this invited commentary is to provide a succinct, theoretical, but intuitive explanation for how women might get closer to their own watershed moment in the mile. [ABSTRACT FROM AUTHOR]

The aim of the present study was to examine whether full leg-length compression tights modify physiological and kinematic measures during treadmill running at a competitive race pace in moderately trained runners. Thirteen males and five females completed two 15-minute running tests at a speed corresponding to a recent race time wearing compression tights or loose-fitting running shorts. Running economy (RE) was determined by oxygen consumption and carbon dioxide expiration during the final 3 minutes of treadmill running. Muscle oxygenation, skin temperature, heart rate (HR), vertical oscillation, step frequency and ground contact time (GCT) were measured continuously. GCT was shorter with compression compared with control trials (p = 0.03), however, no differences in RE, muscle oxygenation, vertical oscillation, step frequency, HR or skin temperature were revealed. Despite a shorter GCT with compression tights, the findings suggest that moderately trained runners do not benefit nor limit physiological responses at a competitive race pace. [ABSTRACT FROM AUTHOR]

Objective: The aim of the present study was to examine whether 10‐20‐30 training (consecutive 1‐min intervals consisting of 30 s at low‐speed, 20 s at moderate‐speed, and 10 s at high‐speed), performed with submaximal effort during the 10‐s high‐speed runs, would lead to improved performance as well as increased maximum oxygen uptake (VO2‐max) and muscle oxidative phosphorylation (OXPHOS). In addition, to examine to what extent the effects would compare to 10‐20‐30 running conducted with maximal effort. Design: Nineteen males were randomly assigned to 10‐20‐30 running performed with either submaximal (SUBMAX; n = 11) or maximal (MAX; n = 8) effort, which was conducted three times/week for 6 weeks (intervention; INT). Before and after INT, subjects completed a 5‐km running test and a VO2‐max test, and a biopsy was obtained from m. vastus lateralis. Results: After compared to before INT, SUBMAX and MAX improved (p < 0.05) 5‐km performance by 3.0% (20.8 ± 0.4 (means±SE) vs. 21.5 ± 0.4 min) and 2.3% (21.2 ± 0.4 vs. 21.6 ± 0.4 min), respectively, and VO2‐max was ~7% higher (p < 0.01) in both SUBMAX (57.0 ± 1.3 vs. 53.5 ± 1.1 mL/min/kg) and MAX (57.8 ± 1.2 vs. 53.7 ± 0.9 mL/min/kg), with no difference in the changes between groups. In SUBMAX, muscle OXPHOS was unchanged, whereas in MAX, muscle OXPHOS subunits (I‐IV) and total OXPHOS (5.5 ± 0.3 vs 4.7 ± 0.3 A.U.) were 9%–29% higher (p < 0.05) after compared to before INT. Conclusion: Conducting 10‐20‐30 training with a non‐maximal effort during the 10‐s high‐speed runs is as efficient in improving 5‐km performance and VO2‐max as maximal effort exercise, whereas increase in muscle OXPHOS occur only when the 10‐s high‐speed runs are performed with maximal effort. [ABSTRACT FROM AUTHOR]

Ratio-scaled VO2 is the widely used method for quantifying running economy (RE). However, this method should be criticized due to its theoretical defect and curvilinear relationship indicated by the allometric scaling, although no consensus has been achieved on the generally accepted exponent b value of body weight. Therefore, this study aimed to provide a quantitative synthesis of the reported exponents used to scale VO2 to body weight. Six electronic databases were searched based on related terms. Inclusion criteria involved human cardiopulmonary testing data, derived exponents, and reported precision statistics. The random-effects model was applied to statistically analyze exponent b. Subgroup and meta-regression analyses were conducted to explore the potential factors contributing to variation in b values. The probability of the true exponent being below 1 in future studies was calculated. The estimated b values were all below 1 and aligned with the 3/4 power law, except for the 95 % prediction interval of the estimated fat-free body weight exponent b. A publication bias and a slightly greater I2 and τ statistic were also observed in the fat-free body weight study cohort. The estimated probabilities of the true body weight exponent, full body weight exponent, and fat-free body weight exponent being lower than 1 were 93.8 % (likely), 95.1 % (very likely), and 94.5 % (likely) respectively. ‘Sex difference’, ‘age category’, ‘sporting background’, and ‘testing modality’ were four potential but critical variables that impacted exponent b. Overall, allometric-scaled RE should be measured by full body weight with exponent b raised to 3/4.

Recent improvements in elite running performances across all distances have been largely attributed to the introduction of advanced footwear technology (AFT), which features a curved and stiff plate working synergistically with a new generation of midsole foams demonstrating enhanced resilience and compliance. These recent improvements appear to be considerably more pronounced in women's events, highlighted by improvements in road racing world records by an average of 3.7% (range: 2.6%–5.2%) compared to mean progressions of 1.5% (range: 1.3%–1.9%) in the same men's events. Although there is a growing body of research investigating the mechanisms underpinning running performance enhancements derived from AFT, there remains no explanation for potential sex-based differences in their benefits. We overview the currently available evidence and highlight why the recent direction of AFT research provides a barrier to progress by focusing primarily on male athletes. We subsequently provide our perspective on why women may be benefiting from the new generation of shoes more than men, suggest potential mechanisms leading to hypotheses that need to be further investigated in upcoming studies, and finally propose that factors outside of footwear innovation may have concurrently driven the recently observed performance evolutions.

In a randomized controlled cross-over study ten male runners (26.7 ± 4.9 years; recent 5-km time: 18:37 ± 1:07 min:s) performed an incremental treadmill test (ITT) and a 3-km time trial (3-km TT) on a treadmill while wearing either carbon fiber insoles with downwards curvature or insoles made of butyl rubber (control condition) in light road racing shoes (Saucony Fastwitch 9). Oxygen uptake, respiratory exchange ratio, heart rate, blood lactate concentration, stride frequency, stride length and time to exhaustion were assessed during ITT. After ITT, all runners rated their perceived exertion, perceived shoe comfort and perceived shoe performance. Running time, heart rate, blood lactate levels, stride frequency and stride length were recorded during, and shoe comfort and shoe performance after, the 3-km TT. All parameters obtained during or after the ITT did not differ between the two conditions [range: p = 0.188 to 0.948 (alpha value: 0.05); Cohen's d = 0.021 to 0.479] despite the rating of shoe comfort showing better scores for the control insoles (p = 0.001; d = −1.646). All parameters during and after the 3-km TT showed no differences (p = 0.200 to 1.000; d = 0.000 to 0.501) between both conditions except for shoe comfort showing better scores for control insoles (p = 0.017; d = −0.919). Running with carbon fiber insoles with downwards curvature did not change running performance or any submaximal or maximal physiological or biomechanical parameter and perceived exertion compared to control condition. Shoe comfort is impaired while running with carbon fiber insoles. Wearing carbon fiber insoles with downwards curvature during treadmill running is not beneficial when compared to running with control insoles.

Wearing an intraoral jaw-protruding splint could enhance respiratory function in clinical settings and eventually exercise performance. Purpose: The authors studied the acute effect of wearing a lower-jaw-forwarding splint at different protruding percentages (30% and 50%) across a wide range of running exercise intensities. Methods: A case study was undertaken with a highly trained and experienced 27-year-old female triathlete. She performed the same incremental intermittent treadmill running protocol on 3 occasions wearing 3 different intraoral devices (30% and 50% maximum range and a control device) to assess running physiological and kinematic variables. Results: Both the 30% and 50% protruding splints decreased oxygen uptake and carbon dioxide production (by 4%–12% and 1%–10%, respectively) and increased ventilation and respiratory frequency (by 7%–12% and 5%–16%, respectively) along the studied running intensities. Exercise energy expenditure (approximately 1%–14%) and cost (7.8, 7.4, and 8.0 J·kg−1·m−1 for 30%, 50%, and placebo devices, respectively) were also decreased when using the jaw-protruding splints. The triathlete's lower limbs' running pattern changed by wearing the forwarding splints, decreasing the contact time and stride length by approximately 4% and increasing the stride rate by approximately 4%. Conclusions: Wearing a jaw-protruding splint can have a positive biophysical effect on running-performance-related parameters. [ABSTRACT FROM AUTHOR]

Purpose: Preconditioning exercise is a widely used strategy believed to enhance performance later the same day. The authors examined the influence of preconditioning exercises 6 hours prior to a time-to-exhaustion (TTE) test during treadmill running. Methods: Ten male competitive runners (age = 26 [3] y, height = 184 [8] cm, weight = 73 [9] kg, maximum oxygen consumption = 72 [7] mL·kg−1·min−1) did a preconditioning session of running (RUN) or resistance exercise (RES) or no morning exercise (NoEx) in a randomized order, separated by >72 hours. The RUN consisted of 15 minutes of low-intensity running and 4 × 15 seconds at race pace (21–24 km·h−1) on a treadmill; RES involved 5 minutes of low-intensity running and 2 × 3 repetitions of isokinetic 1-leg shallow squats with maximal mobilization. Following a 6-hour break, electrically evoked force (m. vastus medialis), countermovement jump, running economy, and a TTE of approximately 2 minutes were examined. Results: Relative to NoEx, no difference was seen for RUN or RES in TTE (mean ± 95% CI: −1.3% ± 3.4% and −0.5% ± 6.0%) or running economy (0.2% ± 1.6% and 1.9% ± 2.7%; all Ps >.05). Jump height was not different for the RUN condition (1.0% ± 2.7%]) but tended to be higher in RES than in the NoEx condition (1.5% ± 1.6%, P =.07). The electrically evoked force tended to reveal low-frequency fatigue (reduced 20:50-Hz peak force ratio) only after RES compared to NoEx (−4.5% ± 4.6%, P =.06). Conclusion: The RUN or RES 6 hours prior to approximately 2 minutes of TTE running test did not improve performance in competitive runners. [ABSTRACT FROM AUTHOR]

Context: The physiological determinants of ultramarathon success have rarely been assessed and likely differ in their contributions to performance as race distance increases. Purpose: To examine predictors of performance in athletes who completed either a 50-, 80-, or 160-km trail race over a 20-km loop course on the same day. Methods: Measures of running history, aerobic fitness, running economy, body mass loss, hematocrit alterations, age, and cardiovascular health were examined in relation to race-day performance. Performance was defined as the percentage difference from the winning time at a given race distance, with 0% representing the fastest possible time. Results: In the 50-km race, training volumes, cardiovascular health, aerobic fitness, and a greater loss of body mass during the race were all related to better performance (all P <.05). Using multiple linear regression, peak velocity achieved in the maximal oxygen uptake test (β = −11.7, P =.002) and baseline blood pressure (β = 3.1, P =.007) were the best performance predictors for the men's 50-km race (r =.98, r2 =.96, P <.001), while peak velocity achieved in the maximal oxygen uptake test (β = −13.6, P =.001) and loss of body mass (β = 12.8, P =.03) were the best predictors for women (r =.94, r2 =.87, P =.001). In the 80-km race, only peak velocity achieved in the maximal oxygen uptake test predicted performance (β = −20.3, r =.88, r2 =.78, P <.001). In the 160-km race, there were no significant performance determinants. Conclusions: While classic determinants of running performance, including cardiovascular health and running fitness, predict 50-km trail-running success, performance in longer-distance races appears to be less influenced by such physiological parameters. [ABSTRACT FROM AUTHOR]

We sought to determine the utility of Stryd, a commercially available inertial measurement unit, to quantify running intensity and aerobic fitness. Fifteen (eight male, seven female) runners (age = 30.2 [4.3] years; V · O2max = 54.5 [6.5] ml·kg−1·min−1) performed moderate- and heavy-intensity step transitions, an incremental exercise test, and constant-speed running trials to establish the maximal lactate steady state (MLSS). Stryd running power stability, sensitivity, and reliability were evaluated near the MLSS. Stryd running power was also compared to running speed, V · O2, and metabolic power measures to estimate running mechanical efficiency (EFF) and to determine the efficacy of using Stryd to delineate exercise intensities, quantify aerobic fitness, and estimate running economy (RE). Stryd running power was strongly associated with V · O2 (R2 = 0.84; p < 0.001) and running speed at the MLSS (R2 = 0.91; p < 0.001). Stryd running power measures were strongly correlated with RE at the MLSS when combined with metabolic data (R2 = 0.79; p < 0.001) but not in isolation from the metabolic data (R2 = 0.08; p = 0.313). Measures of running EFF near the MLSS were not different across intensities (~21%; p > 0.05). In conclusion, although Stryd could not quantify RE in isolation, it provided a stable, sensitive, and reliable metric that can estimate aerobic fitness, delineate exercise intensities, and approximate the metabolic requirements of running near the MLSS. [ABSTRACT FROM AUTHOR]

This systematic review and meta-analysis investigated the effects of exercise-induced muscle damage (EIMD) on sub-maximal and maximal effort running performance. Physiological responses during sub-maximal running across two exercise stages (low intensity < 75% V. O 2 max and high intensity > 75% V. O 2 max ) were meta-analytically examined 24- and 48-hours after EIMD. Delayed onset muscle soreness (DOMS), intramuscular enzymes (creatine kinase [CK] and myoglobin [Mb]) and muscle function at the same time points were examined to confirm EIMD. Alterations to maximal-effort running performance 24- and 48-hours after EIMD were qualitatively analysed. Significant increases in DOMS, intramuscular enzymes, and decreases in muscle function were found 24 and 48 h after EIMD (P < 0.05). During low intensity running (< 75% V. O 2 max ), running economy (RE) and ventilation ( V. E) were unchanged 24 h after EIMD (P > 0.05), however, were significantly increased at 48 h (P < 0.05). Physiological responses during high intensity running (> 75% V. O 2 max ) were all significantly increased 24 and 48 h after EIMD (P < 0.05). There was insufficient number of studies for maximal-effort running performance (time-to-exhaustion and time-trial performance) to be meta-analysed, however, 3 studies reported that outcome measures were impaired for up to 48 h post-EIMD. Endurance runners contemplating eccentric exercise to improve performance should consider the effects that EIMD has on running performance and periodise training accordingly. [ABSTRACT FROM AUTHOR]

There is debate and confusion over how to evaluate the biomechanical effects of running shoe design. Here, we use an evolutionary perspective to analyze how key design features of running shoes alter the evolved biomechanics of the foot, creating a range of tradeoffs in force production and transmission that may affect performance and vulnerability to injury. [ABSTRACT FROM AUTHOR]

Introduction Modern running shoes have revolutionized long-distance performances by decreasing the amount of oxygen athletes need when running at a given speed, which is termed running economy. In 2022, World Athletics imposed an upper limit of 40 mm for midsole thickness, possibly to prevent shoes from having an overemphasized role in performance. This ceiling, however, seems arbitrary, and a better understanding of whether midsole thickness affects running economy is needed. This study therefore investigated if midsole thickness affects oxygen consumption both indoors and outdoors, as early findings from treadmill studies may not translate to overground running. Methods Following a familiarization trial including an incremental test, 16 well-trained male runners (weight 70 ± 6 kg, age 28 ± 5 years, peak oxygen uptake, V̇O2peak 64 ± 4 ml O2･kg-1･min-1, peak running speed 20.0 ± 0.8 km･h-1) completed two testing visits, once on a treadmill and once on a track, each consisting of twelve 5-min runs at submaximal speed (16 km･h-1) alternating three different footwear conditions: an entry-level running shoe (EL, 30 mm midsole thickness) and two carbon-plated modern running shoes with midsole thickness of 40 and 50 mm, respectively. The shoe order was randomized and balanced between each of the four replicates. Gas exchange and heart rate were continuously measured throughout the runs. Results Running with 40 mm shoes reduced V̇O2 compared with EL shoes by 2.4 ± 1.1% on the treadmill and 4.0 ± 1.2% when running overground (both p < 0.001). Running with 50mm shoes also decreased V̇O2 compared with EL shoes both on the treadmill (-2.7 ± 1.6%, p < 0.001) and overground (-4.6 ± 1.8%, p < 0.001), but no differences were detected between the modern shoes (40 mm vs. 50 mm treadmill: +0.3 ± 1.3%, p = 0.586; overground: +0.6 ± 1.4%, p = 0.189). Similarly, heart rate was lower compared with the EL shoes in both the 40 mm shoes (treadmill -1.3 ± 0.6%; overground -2.0 ± 0.6%; both p < 0.001) and 50 mm shoes (treadmill -1.6 ± 0.7%; overground -2.3 ± 0.6%, both p < 0.001), but no differences were detected between the modern shoes (40 mm vs. 50 mm treadmill: +0.3% ± 0.6%, p = 0.106; overground: +0.4 ± 0.6%, p = 0.090). Interestingly when running overground V̇O2 decreased over time for the 50 mm shoes, reaching significance between replicates 1 and 4 (p = 0.017), which was not the case for the 40 mm shoes (p = 0.817). The V̇O2 ratio between the 50 mm and 40 mm shoes was 1.003 in replicate 1 and 0.987 in replicate 4 (p = 0.108). Discussion/Conclusion Our data suggests that a 50 mm midsole does not offer significant benefits compared with race-legal 40 mm midsole shoes when tested over short durations. The 50 mm shoes cause a noticeable decrease in V̇O2 over time when used outdoors, which may reflect a learning effect to this unfamiliar midsole thickness. Longer test sessions may be necessary to reveal the actual impact on running economy of shoes with over 40 mm midsoles.

IntroductionThe present study investigated the role of training intensity in the dose–response relationship between endurance training and cardiorespiratory fitness (CRF). The hypothesis was that beginners would benefit from an increase in training intensity after an initial training phase, even if the energy expenditure was not altered. For this purpose, 26 weeks of continuous moderate training (control group, CON) was compared to training with gradually increasing intensity (intervention group, INC) but constant energy expenditure.MethodsThirty-one healthy, untrained subjects (13 men, 18 women; 46 ± 8 years; body mass index 25.4 ± 3.3 kg m−2; maximum oxygen uptake, VO2max 34 ± 4 ml min−1 kg−1) trained for 10 weeks with moderate intensity [3 days/week for 50 min/session at 55% heart rate reserve (HRreserve)] before allocation to one of two groups. A minimization technique was used to ensure homogeneous groups. While group CON continued with moderate intensity for 16 weeks, the INC group trained at 70% HRreserve for 8 weeks and thereafter participated in a 4 × 4 training program (high-intensity interval training, HIIT) for 8 weeks. Constant energy expenditure was ensured by indirect calorimetry and corresponding adjustment of the training volume. Treadmill tests were performed at baseline and after 10, 18, and 26 weeks.ResultsThe INC group showed improved VO2max (3.4 ± 2.7 ml kg−1 min−1) to a significantly greater degree than the CON group (0.4 ± 2.9 ml kg−1 min−1) (P = 0.020). In addition, the INC group exhibited improved Vmax (1.7 ± 0.7 km h−1) to a significantly greater degree than the CON group (1.0 ± 0.5 km h−1) (P = 0.001). The reduction of resting HR was significantly larger in the INC group (7 ± 4 bpm) than in the CON group (2 ± 6 bpm) (P = 0.001). The mean heart rate in the submaximal exercise test was reduced significantly in the CON group (5 ± 6 bpm; P = 0.007) and in the INC group (8 ± 7 bpm; P = 0.001), without a significant interaction between group and time point.ConclusionIncreasing intensity leads to greater adaptations in CRF than continuing with moderate intensity, even without increased energy expenditure. After 26 weeks of training in the moderate- and higher-intensity domain, energy-matched HIIT elicited further adaptations in cardiorespiratory fitness. Thus, training intensity plays a crucial role in the dose–response relationship between endurance training and fitness in untrained but healthy individuals. Clinical Trial Registrationhttps://www.drks.de/DRKS00031445, identifier DRKS00031445.

Context: Bodyweight-supporting treadmills are popular rehabilitation tools for athletes recovering from impact-related injuries because they reduce ground reaction forces during running. However, the overall metabolic demand of a given running speed is also reduced, meaning athletes who return to competition after using such a device in rehabilitation may not be as fit as they had been prior to their injury. Objective: To explore the metabolic effects of adding incline during bodyweight-supported treadmill running. Design: Cross-sectional. Setting: Research laboratory. Participants: Fourteen apparently healthy, recreational runners (6 females and 8 males; 21 [3] y, 1.71 [0.08] m, 63.11 [6.86] kg). Interventions: The participants performed steady-state running trials on a bodyweight-supporting treadmill at 8.5 mph. The control condition was no incline and no bodyweight support. All experimental conditions were at 30% bodyweight support. The participants began the sequence of experimental conditions at 0% incline; this increased to 1%, and from there on, 2% incline increases were introduced until a 15% grade was reached. Repeated-measures analysis of variance was used to compare all bodyweight-support conditions against the control condition. Main Outcome Measures: Oxygen consumption, heart rate, and rating of perceived exertion. Results: Level running with 30% bodyweight support reduced oxygen consumption by 21.6% (P <.001) and heart rate by 12.0% (P <.001) compared with the control. Each 2% increase in incline with bodyweight support increased oxygen consumption by 6.4% and heart rate by 3.2% on average. A 7% incline elicited similar physiological measures as the unsupported, level condition. However, the perceived intensity of this incline with bodyweight support was greater than the unsupported condition (P <.001). Conclusions: Athletes can maintain training intensity while running on a bodyweight-supporting treadmill by introducing incline. Rehabilitation programs should rely on quantitative rather than qualitative data to drive exercise prescription in this modality. [ABSTRACT FROM AUTHOR]

This study aimed to map the scientific production on training methods for 5 to 10 km long-distance running by means of a bibliometric analysis. PubMed, SciELO and Lilacs databases were used, and data were collected until December 31, 2019. The analysis included experimental studies with the intervention of training methods in runners. Data were analyzed descriptively. It was found that the first article was published in 1981 and 2018 was the year with the highest number of publications. The United States was the country with the highest number of publications, authors and journals. The most frequently cited methods were continuous execution and interval execution. Consequently, the main results were an increase in running economy, VO2max and a reduction in time trial.

Eccentric contractions predispose muscles to damage. Type II muscle fibers are more susceptible than type I, so it seems that contraction velocity interferes in mechanical stress and thus muscle damage. The purpose of this study was to investigate the effect of contraction velocity of acute dominant knee extensor eccentric exercise-induced muscle damage (EIMD) on running economy and metabolic responses in trained young females. Twenty-one trained young females were randomly assigned into two groups: high-velocity contraction eccentric exercise (240°s-1) and low-velocity (60°s-1). To induce muscle damage subjects, in high and low-velocity groups performed 20 and 5 sets of 15 repetitions, respectively, with a load equal to 150٪ of the maximal voluntary isometric contraction (MVIC) torque of knee extensors with a dominant limb. Then; MVIC of knee extensors was recorded before, one and 48 h after EIMD, and running economy (submaximal Steady-state vo2), and metabolic responses were recorded at 60, 70, and 80% of pre-determined vVO2max, 24 h before and 48 h after EIMD. Both exercise bouts resulted in significant changes in MVIC of knee extensor (p

Despite being an intricate part of advanced footwear technology, the impact of midsole thickness is not well understood. While some individuals have speculated an increased midsole thickness might bequeath an unfair performance advantage, others have suggested it may have a detrimental impact on frontal plane ankle stability. Therefore, the purpose of this study was to determine the influence of midsole thickness on running economy, and frontal plane ankle stability. Twenty one recreational runners (ten female, and eleven male) participated in this study, performing five-minute treadmill running trials in four footwear conditions. The footwear conditions were nearly identical except for their midsole thicknesses which ranged from 35- to 50-mm in increments of 5-mm. Midsole thickness was not found to influence the energetic cost of running however, it was found to decrease frontal plane ankle stability. Given these results World Athletic restrictions on midsole thickness may be unnecessary and worthy of reconsideration. [ABSTRACT FROM AUTHOR]

This preliminary study examined the effects of wearing an elevation training mask® 2.0 (ETM) during high-intensity interval training (HIIT) on the aerobic capacity of young men. Twenty-six young men were recruited and randomly divided into an experimental group (EG, n = 13) and a control group (CG, n = 13). The former performed HIIT on a running platform while wearing an ETM, and the latter performed HIIT only. Before and after the intervention, the following parameters were measured: exercise performance indicator is a 3000-m running test; aerobic capacity indicators are maximal oxygen uptake (VO2max), ventilatory anaerobic threshold (VT), and running economy (RE); the physiological indicators are blood, pulmonary function, and cardiac function. After 6 weeks of intervention, there were significant differences (p < 0.05) between the time and time × group interaction for the 3000-m running time. There were no significant differences (p > 0.05) in VO2max between the time and time × group interaction. The VT and RE demonstrated significant differences (p < 0.05) between the time and time × group interaction. Among the physiological indicators, pulmonary and cardiac function differed significantly (p < 0.05) be-tween the time and time × group interaction. Blood parameters showed no significant differences (p > 0.05) between the time points and time × group interaction. These preliminary results suggest that using ETM in conjunction with HIIT for 6 weeks increased young men's aerobic performance much more than conventional HIIT. This effect may be attributed to the significantly improved respiratory function and cardiac function caused by the combination of ETM with HIIT. [ABSTRACT FROM AUTHOR]

The acute effects of maltodextrin (MD) ingestion combined with dietary nitrate (NO3-) on running economy (RE), substrate oxidation, and muscle oxygenation during running were investigated. Ten male marathon runners participated in a double-blind crossover design, receiving either 1.5 g MD·kg-1 BM (MD) or an isocaloric co-ingestion of 1.5 g MD·kg-1 BM and 500 mg NO3-beverage (MDNO). Measurements were taken at various stages to assess RE, followed by a 60-minute run at 70% of VO2 peak. The results showed no significant differences in RE, substrate oxidation, or muscle oxygenation between MD and MDNO. However, the respiratory exchange ratio (RER) was significantly lower during high-intensity prolonged running following MDNO compared to MD. In conclusion, acute co-ingestion of MD with dietary NO3- may impact aerobic energy production but does not significantly affect RE or muscle oxygenation during high-intensity prolonged running. [ABSTRACT FROM AUTHOR]

Is step frequency (SF) related to running economy and how? This is the main question we have tried to answer in this study. It is a well-known biomechanical variable used in scientific and practical analysis of running technique. A systematic review was carried out to analyse available literature of the field. Scopus, Web of Science and ScienceDirect databases were used for article search. In total 249 articles matched defined queries and after exclusion, 12 were used in the review. After analysis of the review, our hypothesis remained unconfirmed. In some cases, step frequency affected the running economy, while in others it did not have a direct impact on it. It might be that SF cannot be considered in isolation from other biomechanical characteristics and it cannot be analysed as a universal criterion for improving running technique and economy. [ABSTRACT FROM AUTHOR]

Purpose: Increases in maximal oxygen uptake (VO2max) and running economy improve performance in long-distance runners. Nevertheless, long-distance runners require sprinting ability to win, especially in the final phase of competitions. The authors determined the relationships between performance and sprinting ability, as well as other abilities in elite long-distance runners. Methods: The subjects were 12 elite long-distance runners. Mean official seasonal best times in 5000-m (5000 m-SB) and 10,000-m (10,000 m-SB) races within 1 year before or after the examination were 13:58.5 (0:18.7) and 28:37.9 (0:25.2) (mean [SD]), respectively. The authors measured 100-m and 400-m sprint times as the index of sprinting ability. They also measured VO2max and running economy (VO2 at 300 m·min-1 of running velocity). They used a single correlation analysis to assess relationships between 5000 m-SB or 10,000 m-SB and other elements. Results: There were significant correlations between 5000 m-SB was significantly correlated with 100-m sprint time (13.3 [0.7] s; r = .68, P = .014), 400-m sprint time (56.6 [2.7] s; r = .69, P = .013), and running economy (55.5 [3.9] mL·kg-1· min-1; r = .59, P = .045). There were significant correlations between 10,000 m-SB and 100-m sprint time (r = .72, P = .009) and 400-m sprint time (r = .85, P < .001). However, there was no significant correlation between 5000 m-SB or 10,000 m-SB and VO2max (72.0 [3.8] mL·kg-1·min-1). Conclusions: The authors' data suggest that sprinting ability is an important indicator of performance in elite long-distance runners. [ABSTRACT FROM AUTHOR]

Is step frequency (SF) related to running economy and how? This is the main question we have tried to answer in this study. It is a well-known biomechanical variable used in scientific and practical analysis of running technique. A systematic review was carried out to analyse available literature of the field. Scopus, Web of Science and ScienceDirect databases were used for article search. In total 249 articles matched defined queries and after exclusion, 12 were used in the review. After analysis of the review, our hypothesis remained unconfirmed. In some cases, step frequency affected the running economy, while in others it did not have a direct impact on it. It might be that SF cannot be considered in isolation from other biomechanical characteristics and it cannot be analysed as a universal criterion for improving running technique and economy.

Half-marathon (HM) is a running sport of increasing popularity in both sexes and in all age groups worldwide during the last years. Many studies have examined several aspects of HM, such as performance and participation trends, sex and age differences, physiological correlates, and training; however, no comprehensive review has ever been contacted to summarize the recently accumulated knowledge. Therefore, the aim of the present study was to review all previous research in this sport, focusing on participation and performance aspects. It was shown that HM runners had similar anthropometric and physiological characteristics as full-marathon runners which should be attributed to the affinity of these two races in terms of metabolic demands. Performance in HM was related with superior scores in aerobic capacity (maximal oxygen uptake, anaerobic threshold and running economy) and training characteristics (sport experience, weekly distance, training speed, frequency of sessions and long single endurance run distance), and lower scores in adiposity-related scores (e.g. body mass, body mass index, body fat percentage and skinfold thickness). Considering the popularity of HM race and the lack of many original studies (compared to FM race), this is an exciting field for scientific research with a large potential for practical applications, since the majority of HM runners are amateur runners in need of sex-, age- and performance-tailored exercise prescription. [ABSTRACT FROM AUTHOR]

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Running economy and velocity at maximal oxygen uptake are considered the most substantial physiological performance indicators in team sports. plyometric training are important techniques that enhance the neuromuscular functioning in athletes. The aim of the present study is to investigates the change in maximal oxygen uptake (VO2max) and running economy (RE). 16 male participants aged 21 years old. Participants underwent pre- and post-intervention tests including running economy, VO2max within 48 h before and after the training protocol. Statistically significant differences were seen in running economy and VO2max after training (p < .01). The current study suggested that plyometric training for 12 weeks can improve running economy and VO2max. [ABSTRACT FROM AUTHOR]

Abstract Background A significant challenge that non-elite collegiate triathletes encounter during competition is the decline in running performance immediately after cycling. Therefore, the purpose of this study was to determine if performing a 40-km bout of cycling immediately before running would negatively influence running economy and mechanical efficiency of running during simulated race conditions in collegiate triathletes. Methods Eight competitive club-level collegiate triathletes randomly performed two trials: cycling for 40 km (Cycle-Run) or running for 5 km (Run–Run), immediately followed by a four-minute running economy and mechanical efficiency of running test at race pace on an instrumented treadmill. Blood lactate, respiratory exchange ratio, mechanical work, energy expenditure, and muscle glycogen were also measured during the four-minute running test. Results Mechanical efficiency of running, but not running economy, was significantly lower in Cycle-Run, compared to Run–Run (42.1 ± 2.5% vs. 48.1 ± 2.5%, respectively; p = 0.027). Anaerobic energy expenditure was significantly higher in the Cycle-Run trial, compared to the Run–Run trial (16.3 ± 2.4 vs. 7.6 ± 1.1 kJ; p = 0.004); while net (151.0 ± 12.3 vs. 136.6 ± 9.6 kJ; p = 0.204) and aerobic energy expenditure (134.7 ± 12.3 vs. 129.1 ± 10.5 kJ; p = 0.549) were not statistically different between trials. Analysis of blood lactate, respiratory exchange ratio, mechanical work, and changes in muscle glycogen revealed no statistically significant differences between trials. Conclusions These results suggest that mechanical efficiency of running, but not running economy, is decreased and anaerobic energy expenditure is increased when a 40-km bout of cycling is performed immediately before running in collegiate triathletes.

Purpose: To determine whether kinetic chain pattern during knee extensor strength training influences quadriceps femoris center of mass and moment of inertia about the hip in a predictable manner as such changes can affect running economy. Methods: Twelve participants completed 8 weeks of both unilateral open (OKC) and closed (CKC) kinetic chain resistance training on opposing legs. Changes in quadriceps femoris muscle volume (VOLQF), center of mass location (CoMQF), and moment of inertia (IQF) about the hip were determined from magnetic resonance images scans. Regional hemodynamics of the vastus lateralis taken at 30% and 70% of muscle length during OKC and CKC bouts early in the training program were measured using near-infrared spectroscopy (NIRS) and used post hoc to predict changes in CoMQF. Results: While increases in VOLQF were similar between OKC (Δ79.5 ± 87.9 cm³) and CKC (Δ60.2 ± 110.5 cm³, p = 0.29), the patterns of hypertrophy differed; a distal shift in CoMQF (Δ2.4 ± 0.4 cm, p < 0.001) and increase in IQF (Δ0.017 ± 0.014 kg m², p < 0.001) occurred in OKC but not in CKC (CoMQF: Δ-2.2 ± 2.0 cm, IQF: Δ-0.022 ± 0.020 kg m², p > 0.05). Regional hemodynamics assessed by NIRS during a single training session displayed similar exercise and regional differences and predicted 39.6% of observed changes in CoMQF. Conclusions: Exercise selection influences muscle shape sufficiently to affect CoMQF and IQF, and these changes may be predicted in part from NIRS measurements during a single workout. Given IQF is inversely related to running economy and since CKC exercise provides a more proximal pattern of hypertrophy than OKC, it may be more preferential for running. The results from the present study also highlight the potential of NIRS as a tool for predicting patterns of hypertrophy between different exercises and exercise conditions [ABSTRACT FROM AUTHOR]