Research and Sport Medicine Center

Navarre, Spain

Research and Sport Medicine Center

Navarre, Spain
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Gonzalez-Izal M.,University of Pamplona | Falla D.,University of Aalborg | Izquierdo M.,Research and Sport Medicine Center | Farina D.,University of Aalborg
Journal of Neuroscience Methods | Year: 2010

This study proposes a method for estimating force loss during fatiguing maximal isokinetic knee extension contractions using a set of features from surface EMG signals recorded from multiple locations over the quadriceps muscle. Nine healthy participants performed fatiguing tests which consisted of 50 and 75 isokinetic leg extensions at a speed of 30°/s and 80°/s in two experimental sessions on different days. The set of data recorded from one of the experimental sessions (at both velocities) was used to train a multi-layer perceptron neural network to associate force loss (direct measure of fatigue) to EMG features. The data from the other session (obtained from the tests at both velocities) were used for testing the neural network performance. The proposed method was compared with a previous approach for the assessment of fatigue (Mapping Index, MI) using a signal to noise metrics computed on the estimated trend of fatigue. The signal to noise ratio obtained with the proposed approach was greater (8.83 ± 1.07) than that obtained with the MI (5.67 ± 1.17) (P<0.05) when the subjects were analyzed individually and when the network was trained over the entire subject group (8.07 vs. 4.42). In conclusion, the proposed approach allows estimation of force loss during maximal dynamic knee extensions from surface EMG signals with greater accuracy than previous methods. © 2010.

Granados C.,University of the Basque Country | Izquierdo M.,Research and Sport Medicine Center | Ibanez J.,Research and Sport Medicine Center | Ruesta M.,Research and Sport Medicine Center | Gorostiaga E.M.,Research and Sport Medicine Center
Journal of Strength and Conditioning Research | Year: 2013

Granados, C, Izquierdo, M, Ibanez, J, Ruesta, M, andGorostiaga, EM. Are there any differences in physical fitess and throwing velocity between national and international elite female handball players? J Strength Cond Res 27(3): 723-732, 2013-This study compared physical characteristics in a 2003 national elite female team (NE; n = 16; fourth in the Spanish Championship) to the same team when it reached international level in 2009 (IE; n = 14; winner of the Spanish Championship and the European Handball Cup). Body height, body mass, body fat, and fat-free mass, 1-repetition maximum bench press (1RMBP), vertical jumping height, handball throwing velocity, power-load relationship of the leg and arm extensor muscles, 5- and 15-m sprint running time, and running endurance were measured in the second competitive mesocycle of a season. Results revealed that, compared with NE, IE players presented similar values in body mass, body height, sprint running time, handball throwing velocity, and jumping, but higher values (p < 0.01-0.05) in age (17%), 1RMBP (15%), power-load relationship of the arm (16%), and leg (10%) extensors, and endurance running velocities (7%). Significant correlations (r = 0.71-0.72, p < 0.05) were observed in IE, but not in NE, between individual values of standing throw and individual values of power at 30% of 1RMBP, and individual values of power at 60% of body mass during half-squat actions. The present results suggest that more experienced, powerful and aerobically conditioned players are at an advantage in international-level female handball. The ball throwing velocity of international elite female handball players depends on their ability to produce muscle power at submaximal loads with the upper and lower extremities. However, in lower-level players, this depends on the level of performance at maximal strength of the upper extremities. © 2013 National Strength and Conditioning Association.

Izquierdo M.,Research and Sport Medicine Center | Gonzalez-Izal M.,Research and Sport Medicine Center | Navarro-Amezqueta I.,Research and Sport Medicine Center | Calbet J.A.L.,University of Las Palmas de Gran Canaria | And 6 more authors.
Medicine and Science in Sports and Exercise | Year: 2011

Purpose: This study examined the effects of heavy resistance training on the relationships between power loss and surface EMG (sEMG) indices and blood metabolite concentrations on dynamic exercise-induced fatigue with the same relative load as in pretraining. Methods: Twelve trained subjects performed five sets consisting of 10 repetitions in the leg press, with 2 min of rest between sets before and after a strength training period. sEMG variables (the mean average voltage, the median spectral frequency, and the Dimitrov spectral index of muscle fatigue) from vastus medialis and lateralis muscles and metabolic responses (i.e., blood lactate, uric acid, and ammonia concentrations) were measured. Results: The peak power loss after the posttraining protocol was greater (61%) than the decline observed in the pretraining protocol (46%). Similar sEMG changes were found for both protocols, whereas higher metabolic demand was observed during the posttraining exercise. The linear models on the basis of the relations found between power loss and changes in sEMG variables were significantly different between pretraining and posttraining, whereas the linear models on the basis of the relations between power loss and changes in blood metabolite concentrations were similar. Conclusions: Linear models that use blood metabolites to map acute exercise-induced peak power changes were more accurate in detecting these changes before and after a short-term training period, whereas an attempt to track peak power loss using sEMG variables may fail after a strength training period. © 2011 by the American College of Sports Medicine.

Los Arcos A.,University of the Basque Country | Yanci J.,University of the Basque Country | Mendiguchia J.,Zentrum Rehabilitation and Performance Center | Gorostiaga E.M.,Research and Sport Medicine Center
Journal of Strength and Conditioning Research | Year: 2014

Los Arcos, A, Yanci, J, Mendiguchia, J, and Gorostiaga, EM. Rating of muscular and respiratory perceived exertion in professional soccer players. J Strength Cond Res 28(11): 3280-3288, 2014-This study investigated, in male professional players: (a) fluctuations in rating of local-muscular (sRPEmus) and central-respiratory (sRPEres) perceived exertion measured after the completion of each training and competitive session, over a 9-week competitive period and (b) the influence of quantitative assessment of different training and competition modes on changes in physical performance. sRPEres, sRPEmus, and heart rate were measured in 21 players in 847 individual training and competitive sessions. Training load was calculated by multiplying sRPEmus or sRPEres by the duration of the training or competition sessions. A test battery (vertical jump, sprint, and endurance running) was performed before and after the studied period. At the end of official matches, average sRPEmus was higher (7.4 ± 0.6; p ≤ 0.05) than sRPEres (6.4 ± 1.3). Significant negative correlations were observed between the values of total training and competition time (r = 20.62; p < 0.01) or total added sRPEmus (r = 20.59; p ≤ 0.05), and vertical jump or sprint running velocity changes, respectively. This suggests that sRPEmus should be considered the main fatigue rating during a soccer match. Training and competition volume may have negative effects on the muscle power performance gains of the legs. Copyright © 2014 National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.

PubMed | University of the Basque Country and Research and Sport Medicine Center
Type: Journal Article | Journal: International journal of sports medicine | Year: 2016

This study aimed to predict the velocity corresponding to the maximal lactate steady state (MLSSV) from non-invasive variables obtained during a maximal multistage running field test (modified University of Montreal Track Test, UMTT), and to determine whether a single constant velocity test (CVT), performed several days after the UMTT, could estimate the MLSSV. Within 4-5 weeks, 20 male runners performed: 1) a modified UMTT, and 2) several 30min CVTs to determine MLSSV to a precision of 0.25kmh(-1). Maximal aerobic velocity (MAV) was the best predictor of MLSSV. A regression equation was obtained: MLSSV=1.425+(0.756MAV); R(2)=0.63. Running velocity during the CVT (VCVT) and blood lactate at 6 (La6) and 30 (La30) min further improved the MLSSV prediction: MLSSV=VCVT+0.503 - (0.266La30-6); R(2)=0.66. MLSSV can be estimated from MAV during a single maximal multistage running field test among a homogeneous group of trained runners. This estimation can be further improved by performing an additional CVT. In terms of accuracy, simplicity and cost-effectiveness, the reported regression equations can be used for the assessment and training prescription of endurance runners.

Mendiguchia J.,Cincinnati Childrens Hospital Medical Center | Mendiguchia J.,Research and Sport Medicine Center | Ford K.R.,Cincinnati Childrens Hospital Medical Center | Ford K.R.,University of Cincinnati | And 6 more authors.
Sports Medicine | Year: 2011

Following the onset of maturation, female athletes have a significantly higher risk for anterior cruciate ligament (ACL) injury compared with male athletes. While multiple sex differences in lower-extremity neuromuscular control and biomechanics have been identified as potential risk factors for ACL injury in females, the majority of these studies have focused specifically on the knee joint. However, increasing evidence in the literature indicates that lumbo-pelvic (core) control may have a large effect on knee-joint control and injury risk. This review examines the published evidence on the contributions of the trunk and hip to knee-joint control. Specifically, the sex differences in potential proximal controllers of the knee as risk factors for ACL injury are identified and discussed. Sex differences in trunk and hip biomechanics have been identified in all planes of motion (sagittal, coronal and transverse). Essentially, female athletes show greater lateral trunk displacement, altered trunk and hip flexion angles, greater ranges of trunk motion, and increased hip adduction and internal rotation during sport manoeuvres, compared with their male counterparts. These differences may increase the risk of ACL injury among female athletes. Prevention programmes targeted towards trunk and hip neuromuscular control may decrease the risk for ACL injuries. © 2011 Adis Data Information BV. All rights reserved.

Mallor F.,University of Pamplona | Leon T.,University of Valencia | Gaston M.,University of Pamplona | Izquierdo M.,Research and Sport Medicine Center
Journal of Biomechanics | Year: 2010

The purpose of this study was to analyze exercise-induced leg fatigue during a dynamic fatiguing task by examining the shapes of power vs. time curves through the combined use of several statistical methods: B-spline smoothing, functional principal components and (supervised and unsupervised) classification. In addition, granulometric size distributions were also computed to allow for comparison of curves coming from different subjects. Twelve physically active men participated in one acute heavy-resistance exercise protocol which consisted of five sets of 10 repetition maximum leg press with 120. s of rest between sets. To obtain a smooth and accurate representation of the data, a basis of 180 B-splines was used. Functional principal component (FPC) analysis was used to find the dominant modes of variation in the curves. A multivariate cluster over the FPC scores and a k-nearest neighbor classification led to three interpretable groups corresponding to different levels of fatigue. Fatigue-induced changes in the shapes of the power curves were evident, in which curves progressively flatten and develop a second power peak. In a practical setting FPC analysis greatly reduces dimensionality and the use of granulometries allows for comparison of the curve shapes without distorting the time scale.In contrast to the present methodology, which considers each curve as a datum, classical statistical approaches using summary parameters of time series may lead to limited information about the impact of dynamic fatiguing protocols on kinematic and kinetic time-course changes in curve shapes. © 2010 Elsevier Ltd.

Brughelli M.,Edith Cowan University | Cronin J.,Edith Cowan University | Cronin J.,University of Auckland | Mendiguchia J.,Research and Sport Medicine Center | And 2 more authors.
Journal of Strength and Conditioning Research | Year: 2010

Contralateral leg deficits between lower limbs during athletic movements are thought to increase the risk of injury and compromise performance. The purpose of this study was to quantify the magnitude of leg deficits during running in noninjured and previously injured Australian Rules football (ARF) players. The players included a group of noninjured ARF players (n = 11) and a group of previously injured ARF players (n = 11; hamstring injuries only). The players in the injured group (IG) had at least 1 acute hamstring injury in the previous 2 years. The legs of the noninjured players (NIG) were classified as right and left, whereas the legs of the injured players were classified as injured or noninjured. The players ran on a nonmotorized force treadmill at approximately 80% of their maximum velocity (Vmax). For the NIG, there were no significant differences between right and left legs for any of the variables. For the IG, the only variable that was significantly (p < 0.001) different between the injured and noninjured leg was horizontal force (175 ± 30 vs. 326 ± 44 N). Furthermore, horizontal force was significantly greater in the noninjured leg (IG) in comparison with either legs in the NIG (19.2% and 20.5%) and significantly less in the injured leg (IG) in comparison with either legs of the NIG (31.5% and 32.7%). In the present study, athletes with previous hamstring injuries had contralateral leg deficits in horizontal but not vertical force during running at submaximal velocities. © 2010 National Strength and Conditioning Association.

Gonzalez-Izal M.,Research and Sport Medicine Center | Gonzalez-Izal M.,Public University of Navarra | Malanda A.,Public University of Navarra | Navarro-Amezqueta I.,Research and Sport Medicine Center | And 4 more authors.
Journal of Electromyography and Kinesiology | Year: 2010

The purpose of this study was to examine acute exercise-induced changes on muscle power output and surface electromyography (sEMG) parameters (amplitude and spectral indices of muscle fatigue) during a dynamic fatiguing protocol. Fifteen trained subjects performed five sets consisting of 10 leg presses (10RM), with 2 min rest between sets. Surface electromyography was recorded from vastus medialis (VM) and lateralis (VL) and biceps femoris (BF) muscles. A number of EMG-based parameters were compared for estimation accuracy and sensitivity to detect peripheral muscle fatigue. These were: Mean Average Voltage, median spectral frequency, Dimitrov spectral index of muscle fatigue (FInsm5), as well as other parameters obtained from a time-frequency analysis (Choi-Williams distributions) such as mean and variance of the instantaneous frequency and frequency variance. The log FInsm5 as a single parameter predictor accounted for 37% of the performance variance of changes in muscle power and the log FInsm5 and MFM as a two factor combination predictor accounted for 44%. Peripheral impairments assessed by sEMG spectral index FInsm5 may be a relevant factor involved in the loss of power output after dynamic high-loading fatiguing task. © 2009 Elsevier Ltd. All rights reserved.

Gonzalez-Izal M.,Public University of Navarra | Malanda A.,Public University of Navarra | Gorostiaga E.,Research and Sport Medicine Center | Izquierdo M.,Health Science University
Journal of Electromyography and Kinesiology | Year: 2012

Muscle fatigue is a common experience in daily life. Many authors have defined it as the incapacity to maintain the required or expected force, and therefore, force, power and torque recordings have been used as direct measurements of muscle fatigue. In addition, the measurement of these variables combined with the measurement of surface electromyography (sEMG) recordings (which can be measured during all types of movements) during exercise may be useful to assess and understand muscle fatigue. Therefore, there is a need to develop muscle fatigue models that relate changes in sEMG variables with muscle fatigue. However, the main issue when using conventional sEMG variables to quantify fatigue is their poor association with direct measures of fatigue. Therefore, using different techniques, several authors have combined sets of sEMG parameters to assess muscle fatigue. The aim of this paper is to serve as a state-of-the-art summary of different sEMG models used to assess muscle fatigue. This paper provides an overview of linear and non-linear sEMG models for estimating muscle fatigue, their ability to assess power loss and their limitations due to neuromuscular changes after a training period. © 2012 Elsevier Ltd.

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