Influence of the World Athletics Stack Height Regulation on Track Running Performance.

ABSTRACT: Ruiz-Alias, SA, Pérez-Castilla, A, Soto-Hermoso, VM, and García-Pinillos, F. Influence of the world athletics stack height regulation on track running performance. J Strength Cond Res 37(11): 2260-2266, 2023-A new footwear regulation based on limiting the stack height (i.e., amount of material between the feet and the ground) has been established by World Athletics to ensure that performance is achieved through the primacy of human effort over technology in running shoes. Analyzing the effect of legal and illegal shoes on running performance is therefore needed to determine its effectiveness. Thus, this study aimed (a) to compare the effect of 2 footwear models categorized as legal and illegal by the World Athletics regulation on track running performance and (b) to analyze the derived metrics of the athletes' biomechanics when using each footwear model at racing paces. Within 1 week, 14 highly trained athletes performed 2 testing sessions composed of 2 time trials of 9- and 3-minute duration with 30 minutes of recovery between them. The athletes wore the "Nike ZoomX Dragonfly" track spikes model and the "Nike ZoomX Vaporfly Next % 2" marathon shoe model in a counterbalanced randomized order. The results revealed that (a) there was only a small worthwhile improvement in the 3-minute time trial when using the marathon shoes of 0.97% (-0.04 to 1.98%) and (b) there was a main effect of footwear in 7 of the 9 biomechanical variables analyzed (p ≤ 0.050). The ground contact time was the unique performance predictor (p = 0.005, adjusted R2 = 0.476). Altogether, the use of legal and illegal running shoes altered the runners form, which only influenced the mid-distance performance.

RunScribe Sacral Gait Lab™ Validation for Measuring Pelvic Kinematics during Human Locomotion at Different Speeds.

Optoelectronic motion capture systems are considered the gold standard for measuring walking and running kinematics parameters. However, these systems prerequisites are not feasible for practitioners as they entail a laboratory environment and time to process and calculate the data. Therefore, this study aims to evaluate the validity of the three-sensor RunScribe Sacral Gait Lab™ inertial measurement unit (IMU) in measuring pelvic kinematics in terms of vertical oscillation, tilt, obliquity, rotational range of motion, and the maximum angular rates during walking and running on a treadmill. Pelvic kinematic parameters were measured simultaneously using an eight-camera motion analysis system (Qualisys Medical AB, GÖTEBORG, Sweden) and the three-sensor RunScribe Sacral Gait Lab™ (Scribe Lab. Inc. San Francisco, CA, USA) in a sample of 16 healthy young adults. An acceptable level of agreement was considered if the following criteria were met: low bias and SEE (<0.2 times the between-subject differences SD), almost perfect (r > 0.90), and good reliability (ICC > 0.81). The results obtained reveal that the three-sensor RunScribe Sacral Gait Lab™ IMU did not reach the validity criteria established for any of the variables and velocities tested. The results obtained therefore show significant differences between the systems for the pelvic kinematic parameters measured during both walking and running.

The Effect of Using Marathon Shoes or Track Spikes on Neuromuscular Fatigue caused by a Long-distance Track Training Session.

This study aims to compare the effect of the Nike ZoomX Dragonfly track spikes and the Nike ZoomX VaporflyNext% 2 marathon shoes on the fatigue manifestations present over and after a long-distance track training session. Thirteen highly trained athletes completed two training sessions (i. e., 9- and 3-minute time trials with complete recovery) with the aforementioned footwear models. The pace, ground contact time, and stride length were measured over the time trials, and maximal countermovement jumps were performed previously and after the training session. The results revealed that, although there was no significant interaction in the pace distribution (p≥0.072), athletes tend to be only able to increase the pace at the last lap with the marathon shoes (5.4 meters [-3.7 to 14.5 meters]) meanwhile with the track spikes it further decreased (-3.1 meters [-9.8 to 3.6 meters]). A reduced ground contact time over the session (p=0.025) and a tendency toward increasing stride length (p=0.09) in the last time trial were observed. The significant interaction on the countermovement jump height (p=0.023; Track spikes: -5.60%; Marathon shoes: 0.61%) also indicates that footwear influences the resulted allostatic load.

A systematic review of the effect of running shoes on running economy, performance and biomechanics: analysis by brand and model.

This systematic review aims to synthesise the effects of current shoe models in each shoe category and their specific features on running economy, performance and biomechanics. Electronic databases such as Web of Science, SPORTDiscuss, PubMed and Scopus were used to identify studies from 2015 to date. Due to the existing lack of consensus to define running shoes, only studies that specified the shoe brand and models used to assess their effect over runners with a certain level of fitness and training routine were included. Quality assessment of cross-sectional and intervention studies was conducted by three independent raters using a modified version of the Quality Index and the PEDro scale, respectively. A total of 36 articles were finally included, involving the analysis of 61 different shoe models over 10 different topics (i.e., running economy, running performance, spatiotemporal parameters, ground reaction forces, joint stiffness, achilles tendon, plantar pressure, tibiofemoral load, foot strike pattern and joint coordination). With this review, runners and practitioners in the field that are concerned about selecting a suitable shoe for performance, training, or injury prevention functionality have clear information about the effects of the current shoe models and their specific features.

Is there association between cutting and jump-landing movement quality in semi-professional football players? Implications for ACL injury risk screening.

OBJECTIVES: To investigate the relationship between the Landing Error Scoring System (LESS) and Cutting Movement Assessment Score (CMAS) to evaluate movement quality, their intra- (INTRAob) and inter-observer (INTERob) reliability, and the comparison between the two drop vertical jump (DVJ) landings (1st and 2nd). DESIGN: Cross-sectional. PARTICIPANTS: 42 male semi-professional soccer players performed three trials of DVJ and 70° change of direction with a ball located as an external focus. MAIN OUTCOME MEASURES: Movement quality was evaluated through 2D video footage using the CMAS and LESS, screened by two observers. Relational, comparative and reliability analyses were conducted. RESULTS: Both tools showed moderate to substantial (ICC = 0.58-0.71), and substantial to almost perfect (ICC = 0.68-0.87) INTRAob and INTERob reliability, respectively. No significant associations were found among CMAS, LESS 1st and 2nd for either scores or risk profiles (r = -0.158-0.202, p > 0.05). LESS 2nd was moderately higher (ES = 0.80-0.83, p = 0.002-0.007) than 1st scores. CONCLUSIONS: CMAS and LESS are reliable tools to evaluate movement quality, although evaluations should be preferably performed by the same observer; ACL injury risk profile's is task-dependent; both landings of the DVJ should be assessed as they represent different biomechanical and neuromuscular control deficits.

The Safe Landing warm up technique modification programme: An effective anterior cruciate ligament injury mitigation strategy to improve cutting and jump-movement quality in soccer players.

The objective of the study was to evaluate the effectiveness of the Safe Landing (SL), a 6-week technique-modification (TM) programme, on cutting and jump-landing movement quality in football players. In a non-randomized design, 32 male semi-professional football players from two Spanish clubs participated in the study: one served as the control group (CG, n = 11), while the other performed the SL (n = 15). Performance and movement quality of drop vertical jump and 70º change of direction (COD70) were evaluated through 2D video footage pre- and post-intervention. In such tasks, the Landing Error Scoring System for first (LESS1) and second (LESS2) landings, and the Cutting Movement Assessment Score (CMAS) were used for assessing movement quality. Pre-to-post changes and baseline-adjusted ANCOVA were used. Medium-to-large differences between groups at post-test were shown in CMAS, LESS1 and LESS2 (p < 0.082, Õ²2 = 0.137-0.272), with small-to-large improvements in SL (p < 0.046, ES=0.546-1.307), and CG remaining unchanged (p > 0.05) pre-to-post. In COD70 performance, large differences were found between groups (p < 0.047, Õ²2 = 0.160-0.253), with SL maintaining performance (p > 0.05, ES=0.039-0.420), while CG moderately decreasing performance (p = 0.024, ES=0.753) pre-to-post. The SL is a feasible and effective TM program to improve movement quality and thus potential injury risk in cutting and landing, while not negatively affecting performance.

Does Arch Stiffness Influence Running Spatiotemporal Parameters? An Analysis of the Relationship between Influencing Factors on Running Performance.

This study aimed to determine the influence of arch stiffness on running spatiotemporal parameters at a common speed for a wide range of endurance runners (i.e., 12 km·h-1). In total, 97 runners, 52 men and 45 women, completed a treadmill running protocol at 12 km·h-1. Spatiotemporal parameters were measured using the OptoGait system, and foot structure was assessed by determining arch stiffness. Since between-sex differences were found in anthropometric and foot structure variables, data analysis was conducted separately for men and women, and body mass and height were considered as covariates. For both sexes, a k-means cluster analysis grouped participants according to arch stiffness, by obtaining a group of low-arch stiffness (LAS group) and a group of high-arch stiffness (HAS group), with significant differences in arch stiffness (p < 0.001, for both men and women). No significant differences between LAS and HAS groups were found in running spatiotemporal parameters, regardless of sex (p ≥ 0.05). For both sexes, the partial correlation analysis reported no significant correlations (p ≥ 0.05) between foot structure variables and running spatiotemporal parameters. The results obtained show no differences in spatiotemporal gait characteristics during running at submaximal velocity between runners with low-arch stiffness and those with high-arch stiffness, regardless of sex. These findings may have important implications for clinicians and coaches by adding more evidence to the debate about the use of static foot classification measures when characterizing the foot and its biomechanics during running.

Effects of 12 weeks of barefoot running on foot strike patterns, inversion-eversion and foot rotation in long-distance runners.

PURPOSE: The purpose of this study was to determine the effects of 12 weeks of barefoot running on foot strike patterns, inversion-eversion and foot rotation in long-distance runners. METHODS: Thirty-one endurance runners with no experience in barefoot running were randomized into a control group and an experimental group who received barefoot training. At pre-test and post-test, all subjects ran at low and high self-selected speeds on a treadmill. Data were collected by systematic observation of lateral and back recordings at 240 Hz. RESULTS: McNemar's test indicated significant changes (p < 0.05) in the experimental group at both high and low speed running in foot strike patterns, reducing the percentage of high rearfoot strikers and increasing the number of midfoot strikers. A significant increase (p < 0.05) of external rotation of the foot and a decrease of inversion occurred at comfortable speed in the experimental group. CONCLUSION: Twelve weeks of barefoot running, applied progressively, causes significant changes in foot strike pattern with a tendency toward midfoot or forefoot strikes, regardless of running speed and significant changes in foot rotation at low speed, while the inversion was reduced in left foot at low speed with a tendency toward centered strike.

Agreement between the spatiotemporal gait parameters from two different wearable devices and high-speed video analysis.

This study aimed to evaluate the concurrent validity of two different inertial measurement units for measuring spatiotemporal parameters during running on a treadmill, by comparing data with a high-speed video analysis (VA) at 1,000 Hz. Forty-nine endurance runners performed a running protocol on a treadmill at comfortable velocity (i.e., 3.25 ± 0.36 m.s-1). Those wearable devices (i.e., Stryd™ and RunScribe™ systems) were compared to a high-speed VA, as a reference system for measuring spatiotemporal parameters (i.e. contact time [CT], flight time [FT], step frequency [SF] and step length [SL]) during running at comfortable velocity. The pairwise comparison revealed that the Stryd™ system underestimated CT (5.2%, p < 0.001) and overestimated FT (15.1%, p < 0.001) compared to the VA; whereas the RunScribe™ system underestimated CT (2.3%, p = 0.009). No significant differences were observed in SF and SL between the wearable devices and VA. The intra class correlation coefficient (ICC) revealed an almost perfect association between both systems and high-speed VA (ICC > 0.81). The Bland-Altman plots revealed heteroscedasticity of error (r2 = 0.166) for the CT from the Stryd™ system, whereas no heteroscedasticity of error (r2 < 0.1) was revealed in the rest of parameters. In conclusion, the results obtained suggest that both foot pods are valid tools for measuring spatiotemporal parameters during running on a treadmill at comfortable velocity. If the limits of agreement of both systems are considered in respect to high-speed VA, the RunScribe™ seems to be a more accurate system for measuring temporal parameters and SL than the Stryd™ system.

How Does Power During Running Change when Measured at Different Time Intervals?

This study aimed to examine how the power output changes while running at a continuous comfortable velocity on a motorized treadmill by comparing running power averaged during different time intervals. Forty-nine endurance runners performed a running protocol on a treadmill at self-selected comfortable velocity. Power output (W) was estimated with the Stryd™ power meter, and it was examined over six recording intervals within the 3-min recording period: 0-10 s, 0-20 s, 0-30 s, 0-60 s, 0-120 s and 0-180 s. The ANOVAs showed no significant differences in the magnitude of the power output between the recording intervals (p=0.276, F=1.614, partial Eta 2 =0.155). An almost perfect association was also observed in the magnitude of the power output between the recording intervals (ICC≥0.999). Bland-Altman plots revealed no heteroscedasticity of error for the power output in any of the between-intervals comparisons (r 2<0.1), although longer recording intervals yield smaller systematic bias, random errors, and narrower limits of agreement for power output. The results show that power data during running, as measured through the Stryd™ system, is a stable metric with negligible differences, in practical terms, between shorter (i. e., 10, 20, 30, 60 or 120 s) and longer recording intervals (i. e., 180 s).

Does stroke performance in amateur tennis players depend on functional power generating capacity?

BACKGROUND: Physical preparation is becoming more important in amateur tennis player training programs. Yet, when studying stroke performance in these players, there is a lack of evidence on the role of functional power generating capacity. The aim of the study was therefore to determine whether functional power generating capacity correlates with speed and accuracy of forehand and backhand groundstrokes in amateur players. We also studied the correlation with handgrip strength as a more classical measurement of general muscle strength. METHODS: A total of 21 male amateur players, aged 33.7±4.6 with 17.1±6.7 years of play, were tested. They performed a medicine ball side throw test, a handgrip dynamometer test, and a stroke performance test. RESULTS: Distance of the medicine ball throw on the dominant side positively correlated to the speed of the fastest forehand (r=0.52; P=0.017) and backhand accuracy (r=0.49; P=0.024). There was also a correlation between the handgrip strength on the dominant side and the speed of the fastest forehand (r=0.52, P=0.019). CONCLUSIONS: We concluded that groundstroke performance in amateur tennis players depends on functional power generating capacity, but that it is not the principal contributing factor.

¿Puede modificarse la cinética de la carrera mediante un programa de entrenamiento descalcista? / Can running kinetics be modified using a barefoot training program?

Introducción: Existe información limitada acerca de los programas de transición a carrera descalza, y este estudio ayudará a incrementar el conocimiento acerca de esta tendencia creciente. Por tanto, el objetivo de este estudio fue determinar el efecto de un programa de entrenamiento descalcista de 12 semanas sobre las variables cinéticas en los corredores de larga distancia. Materiales y métodos: Un total de 32 corredores de larga distancia, bien entrenados, y habitualmente calzados, fueron distribuidos aleatoriamente en un grupo experimental para llevar a cabo un programa de entrenamiento descalcista. Durante las pruebas previas y posteriores, todos los participantes realizaron las pruebas a velocidades de carrera de recuperación y competitiva auto-seleccionadas, utilizando sus zapatillas deportivas en una cinta ergométrica. Ambas situaciones se registraron con un sistema de calificación por vídeo de 240Hz, y se analizaron mediante un programa de edición de vídeo 2D con técnicas fotogramétricas. Se midieron el tiempo de contacto, la duración del paso y la cadencia mediante análisis de la varianza (ANOVA) con mediciones repetidas. Resultados: En la prueba posterior, solo la duración de la fase de aterrizaje a alta velocidad reflejó una diferencia significativa, logrando el grupo experimental un tiempo inferior que el grupo control tras el programa de entrenamiento descalcista (0,032±0,007s frente a 0,038±0,006s). Con relación a las diferencias entre grupos, el grupo control reflejó un incremento en la duración de la fase de apoyo a baja velocidad (Δ=0,014s; p=0,024) y una reducción del tiempo de vuelo a alta velocidad (Δ=−0,014s; p=0,034). Además, el grupo experimental logró una reducción de la duración de la fase de aterrizaje a alta velocidad (Δ=−0,008s; p=0,004). Conclusiones: Un programa de carrera descalcista de 12 semanas modifica la duración de la fase de aterrizaje a alta velocidad, que es más corta en los corredores de larga distancia. Por contra, los corredores que no realizaron el entrenamiento reflejaron un incremento de la duración de la fase de apoyo a baja velocidad

Introduction: There is limited information about barefoot transition programs and this study will help to increase knowledge about this growing trend. The purpose of this study was, therefore, to determine the effect of a twelve-week barefoot training program on kinematic variables in long-distance runners. Materials and methods: A total of 32 well-trained, habitually shod, long-distance runners, randomized in a control group and an experimental group who undertook a barefoot training program. At pre-test and post-test, all participants, wearing their usual sneakers, performed running tests at self-selected recovery and competitive running speeds on a treadmill. Both conditions were recorded with a 240Hz video rate system and analyzed using a 2-D video editing program using photogrammetric techniques. Contact time, flight time, step duration and cadence were measured using an analysis of variance (ANOVA) with repeated measures was performed. Results: In posttest, only the duration of landing phase at high speed showed significant difference, the experimental group achieved a shorter time than the control group after the barefoot training program (0.032±0.007s vs. 0.038±0.006s). In relation to within-group differences, the control group showed an increase of duration of stance phase at low speed (Δ=0.014s, p=0.024) and a reduction of flight time at high speed (Δ=−0.014s, p=0.034). Moreover, the experimental group achieved a reduction of duration of landing phase at high speed (Δ=−0.008s, p=0.004). Conclusions: A twelve-week program of barefoot running changes the duration of the landing phase at high speed, being shorter in long-distance runners. In contrast, the runners who did not undertake the training showed an increase of duration of stance phase at low speed

Physical activity, weight and functional limitations in elderly Spanish people: the National Health Survey (2009-2014).

Background: The purpose of this study was to analyze physical activity (PA), functional limitations, weight status, self-perceived health status and disease or chronic health problems in older people aged 65 and over using the European Health Survey in Spain (EHSS) conducted one in 2009 and one in 2014. Methods: This study included 12,546 older people, 6026 [2330 men and 3696 women; age (Mean, SD) =75.61 ± 7.11 years old] in 2009 and 6520 [2624 men and 3896 women; age (Mean, SD) =75.90 ± 7.59 years old] in 2014. The sample was divided into three age groups: 65-74 years old, 75-84 years old and ≥85 years old. Results: In 2014, participants exhibited lower values for moderate PA, and self-perceived health status compared to 2009. Moreover, in 2014 more people with disease or chronic health problems, and severe difficulty walking 500 m without assistance were found and severe difficulty going up and down 12 stairs than people in 2009. In relation to weight status there were no significant differences between older people in 2009 and 2014. Conclusions: From 2009 to 2014, the PA levels of Spanish older people have decreased, while the BMI has not increased. That fact is in consonance with a worst perception of health status in 2014 and with an increase of their disease levels. The current data highlight the importance of incorporating exercise programmes at an early stage of ageing in order to preserve physical performance, and to prevent the negative consequences of ageing.

Effects of different percentages of body weight support on spatiotemporal step characteristics during running.

This study aimed to determine the effect of different percentages of body weight support (BWS) on spatiotemporal step characteristics during running. 26 endurance runners (age: 37 ± 9 years) completed a running treadmill protocol consisting of 6 different conditions (BWS combinations: 0-50%), with velocity maintained at 12 km/h. Each condition lasted 1 minute. Step angle, ground contact time (CT), flight time (FT), step length (SL) and frequency (SF), and duration of phases during stance time (phase1: initial contact; phase2: midstance; phase3: propulsion) were measured for every step during the test using a photoelectric cell system. Compared with the baseline condition (100% BW), FT was longer, CT was shorter, SL was longer, SF was lower, and the step angle was higher with each increase in BWS (p < 0.05). Also, some changes were observed in the duration of phases during stance time: phase1 did not experience changes across experimental conditions (p = 0.096), phase2 decreased and phase3 increased as BW was supported (p < 0.05). These results indicate that as BW was supported, runners showed longer FT and SL, shorter CT, lower SF, and greater step angle as well as some changes in the phases during the ground contact. Therefore, this study highlights the effect of different percentages of BWS on spatiotemporal parameters.

Lack of Influence of Muscular Performance Parameters on Spatiotemporal Adaptations With Increased Running Velocity.

Roche-Seruendo, LE, García-Pinillos, F, Haicaguerre, J, Bataller-Cervero, AV, Soto-Hermoso, VM, and Latorre-Román, PÁ. Lack of influence of muscular performance parameters on spatiotemporal adaptations with increased running velocity. J Strength Cond Res 32(2): 409-415, 2018-This study aimed to analyze the influence of muscular performance parameters on spatiotemporal gait characteristics during running when gradually increasing speed. Fifty-one recreationally trained male endurance runners (age, 28 ± 8 years) voluntarily participated in this study. Subjects performed a battery of jumping tests (squat jump, countermovement jump, and 20-cm drop jump), and after that, the subjects performed an incremental running test (10-20 km·h) on a motorized treadmill. Spatiotemporal parameters were measured using the OptoGait system. Cluster k-means analysis grouped subjects according to the jumping test performance, by obtaining a group of good jumpers (n = 19) and a group of bad jumpers (n = 32). With increased running velocity, contact time was shorter and flight time and step length were longer, whereas cadence and stride angle were greater (p < 0.001). No significant differences between groups (p ≥ 0.05) were found at any running speed. The results obtained indicate that increased running velocity produced no differences in spatiotemporal adaptations between those runners with good jumping ability and those with poor jumping ability. Based on that, it seems that muscular performance parameters do not play a key role in spatiotemporal adaptations experienced by recreational endurance runners with increased velocity. However, taken into consideration the well-known relationship between running performance and neuromuscular performance, the authors suggest that muscular performance parameters would be much more determinant in the presence of fatigue (exhausted condition) or in the case of considering other variables such as running economy or kinetic.

Efectos agudos de la carrera sin zapatillas y sus requisitos en la cinemática de las extremidades inferiores en corredores resistentes habitualmente calzados / Acute effects of barefoot running and running requirement on lower-limb kinematics in habitually shod endurance runners

El objetivo de este estudio fue analizar las variables cinemáticas en la carrera sin zapatillas y utilizando zapatillas convencionales específicas para carrera, a nivel de velocidad confortable y exigente. Los participantes fueron 60 corredores recreativos sanos (edad, 35,6 ± 11,7 años, índice de masa corporal, 22,9 ± 2,4 kg/m2), quienes realizaron las pruebas descalzos sobre una cinta a velocidades confortable y exigente, seleccionadas por ellos mismos. Se utilizaron técnicas fotogramétricas (2D). En la carrera sin zapatillas, el tiempo de contacto fue menor (p < 0,001) a velocidad exigente, el tiempo de vuelo fue más corto a velocidades confortable (p < 0,05) y exigente (p < 0,05), y la frecuencia de la zancada fue superior en ambas velocidades (p < 0,001). Además, en la carrera sin zapatillas los corredores aterrizaron con una flexión de rodillas considerablemente superior (p < 0,05), menor dorsiflexión de tobillos (p < 0,001) y menor flexión de rodillas en el despegue, a velocidad exigente (p = 0,002) en la carrera con zapatillas. En conclusión, el presente estudio ha aportado una evidencia que sugiere que se producen cambios agudos en las variables temporales y cinemáticas en la carrera con/sin zapatillas a baja y alta velocidad, en los corredores que utilizan normalmente zapatillas. Se hallaron diferencias significativas en cuanto a sucesos espaciotemporales en carrera sin zapatillas, con una mayor flexión de rodillas y dorsiflexión de tobillos. Al aumentar la velocidad al correr descalzos, la duración de las variables de tiempo disminuyó considerablemente tanto en velocidad confortable como en exigente (p < 0,001). Debido a ello, el ciclo de zancada y de marcha fue considerablemente más rápido y, por tanto, se produjo una mayor frecuencia de zancada (AU)

The aim of this study was to analyse kinematic variables when running barefoot and when wearing conventional running shoes at comfortable and demanding running speeds. Sixty healthy recreational male runners (age = 35.6 ± 11.7 years old, body mass index = 22.9 ± 2.4 kg/m 2 ) performed trials in shod/barefoot running conditions on a treadmill At self-selected comfortable and demanding speeds. Photogrammetric techniques (2D) were employed. In barefoot conditions, contact time was shorter (p < 0.001) at demanding speed, flight time was shorter at comfortable (p < 0.05) and demanding (p < 0.05) speeds, and there was greater stride frequency at both speeds (p < 0.001). In addition, in barefoot conditions, runners landed with significantly greater knee flexion (p < 0.05); lower ankle dorsiflexion (p < 0.001); and lower knee flexion in take-off at demanding speed (p = 0.002) compared with shod conditions. In conclusion, the current study has provided evidence to suggest that acute changes occur in the temporal variables and kinematics between shod/barefoot conditions at low and high speeds in habitually shod runners. Significant differences were found in spatial- - -temporal events between shod/barefoot conditions, with shorter times in barefoot conditions with greater knee flexion and ankle dorsiflexion. When speed was increased in barefoot conditions, duration of timing variables decreased significantly both comfortable and demanding speed (p < 0.001). Because of this, stride and gait cycle was significantly faster and thus there was a higher stride frequency (AU)

A High Intensity Interval Training (HIIT)-Based Running Plan Improves Athletic Performance by Improving Muscle Power.

García-Pinillos, F, Cámara-Pérez, JC, Soto-Hermoso, VM, and Latorre-Román, PÁ. A High Intensity Interval Training (HIIT)-based running plan improves athletic performance by improving muscle power. J Strength Cond Res 31(1): 146-153, 2017-This study aimed to examine the effect of a 5-week high-intensity intermittent training (HIIT)-based running plan on athletic performance and to compare the physiological and neuromuscular responses during a sprint-distance triathlon before and after the HIIT period. Thirteen triathletes were matched into 2 groups: the experimental group (EG) and the control group (CG). The CG was asked to maintain their normal training routines, whereas the EG maintained only their swimming and cycling routines and modified their running routine. Participants completed a sprint-distance triathlon before (pretest) and after (posttest) the intervention period. In both pretest and posttest, the participants performed 4 jumping tests: before the race (baseline), postswim, postcycling, and postrun. Additionally, heart rate was monitored (HRmean), whereas rate of perceived exertion (RPE) and blood lactate accumulation (BLa) were registered after the race. No significant differences (p ≥ 0.05) between groups were found before HIIT intervention (at pretest). Significant group-by-training interactions were found in vertical jumping ability and athletic performance: the EG improved jumping performance (∼6-9%, p ≤ 0.05, effect size (ES) > 0.7), swimming performance (p = 0.013, ES = 0.438), and running time (p = 0.001, ES = 0.667) during the competition, whereas the CG remained unchanged (p ≥ 0.05, ES < 0.4). No changes (p ≥ 0.05, ES < 0.4) were observed in RPE, HRmean, and BLa. A linear regression analysis showed that ΔCMJ predicted both the ΔRu_time (R = 0.559; p = 0.008) and the ΔOverall_time (R = 0.391; p = 0.048). This low-volume, HIIT-based running plan combined with the high training volumes of these triathletes in swimming and cycling improved athletic performance during a sprint-distance triathlon. This improvement may be due to improved neuromuscular characteristics that were transferred into improved muscle power and work economy.

How does high-intensity intermittent training affect recreational endurance runners? Acute and chronic adaptations: A systematic review.

OBJECTIVE: This systematic review aimed to critically analyze the literature to determine how high-intensity intermittent training (HIIT) affects recreational endurance runners in the short- and long-term. METHODS: Electronic databases were searched for literature dating from January 2000 to October 2015. The search was conducted using the key words "high-intensity intermittent training" or "high-intensity interval exercise" or "interval running" or "sprint interval training" and "endurance runners" or "long distance runners". A systematic approach was used to evaluate the 783 articles identified for initial review. Studies were included if they investigated HIIT in recreational endurance runners. The methodological quality of the studies was evaluated using the Physiotherapy Evidence Database (PEDro) scale (for intervention studies) and the modified Downs and Black Quality Index (for cross-sectional studies). RESULTS: Twenty-three studies met the inclusionary criteria for review. The results are presented in 2 parts: cross-sectional (n = 15) and intervention studies (n = 8). In the 15 cross-sectional studies selected, endurance runners performed at least 1 HIIT protocol, and the acute impact on physiological, neuromuscular, metabolic and/or biomechanical variables was assessed. Intervention studies lasted a minimum of 4 weeks, with 10 weeks being the longest intervention period, and included 2 to 4 HIIT sessions per week. Most of these studies combined HIIT sessions with continuous run (CR) sessions; 2 studies' subjects performed HIIT exclusively. CONCLUSION: HIIT-based running plans (2 to 3 HIIT sessions per week, combining HIIT and CR runs) show athletic performance improvements in endurance runners by improving maximal oxygen uptake and running economy along with muscular and metabolic adaptations. To maximize the adaptations to training, both HIIT and CR must be part of training programs for endurance runners.

Do Running Kinematic Characteristics Change over a Typical HIIT for Endurance Runners?

García-Pinillos, F, Soto-Hermoso, VM, and Latorre-Román, PÁ. Do running kinematic characteristics change over a typical HIIT for endurance runners?. J Strength Cond Res 30(10): 2907-2917, 2016-The purpose of this study was to describe kinematic changes that occur during a common high-intensity intermittent training (HIIT) session for endurance runners. Twenty-eight male endurance runners participated in this study. A high-speed camera was used to measure sagittal-plane kinematics at the first and the last run during a HIIT (4 × 3 × 400 m). The dependent variables were spatial-temporal variables, joint angles during support and swing, and foot strike pattern. Physiological variables, rate of perceived exertion, and athletic performance were also recorded. No significant changes (p ≥ 0.05) in kinematic variables were found during the HIIT session. Two cluster analyses were performed, according to the average running pace-faster vs. slower, and according to exhaustion level reached-exhausted group vs. nonexhausted group (NEG). At first run, no significant differences were found between groups. As for the changes induced by the running protocol, significant differences (p ≤ 0.05) were found between faster and slower athletes at toe-off in θhip and θknee, whereas some changes were found in NEG in θhip during toe-off (+4.3°) and θknee at toe-off (-5.2°) during swing. The results show that a common HIIT session for endurance runners did not consistently or substantially perturb the running kinematics of trained male runners. Additionally, although some differences between groups have been found, neither athletic performance nor exhaustion level reached seems to be determinant in the kinematic response during a HIIT, at least for this group of moderately trained endurance runners.

Spatio-temporal gait disorder and gait fatigue index in a six-minute walk test in women with fibromyalgia.

BACKGROUND: Gait disorders in fibromyalgia patients affect several gait parameters and different muscle recruitment patterns. The aim of this study was to assess the gait differences observed during a six-minute walk test between fibromyalgia patients and healthy controls. METHODS: Forty-eight women with fibromyalgia and 15 healthy women were evaluated. Fibromyalgia patients met the American College of Rheumatology criteria for fibromyalgia selected of an ambulatory care. Both patients and controls had a negative history of musculoskeletal disease, neurological disorders, and gait abnormalities. The 15 controls were healthy women matched to the patients in age, height and body weight. Spatio-temporal gait variables and the rate of perceived exertion during the six-minute walk test (all subjects) and Fibromyalgia Impact Questionnaire (fibromyalgia subjects) were evaluated. All walking sets on the GaitRITE were collected and the gait variables were selected at three stages during the six-minute walk test: two sets at the beginning, two sets at 3 min and two sets at the end of the test. In addition, the Fibromyalgia Impact Questionnaire was used for the fibromyalgia patients. FINDINGS: Fibromyalgia patients showed a significant decrease in all spatio-temporal gait variables at each of the three stages and had a lower walk distance covered in the six-minute walk test and higher rate of perceived exertion. No correlations were found between the Fibromyalgia Impact Questionnaire and gait variables. The fibromyalgia and control subjects showed lower gait fatigue indices between the middle and last stages. INTERPRETATION: Gait analysis during a six-minute walk test is a good tool to assess the fatigue and physical symptoms of patients with fibromyalgia.