A novel application of entropy analysis for assessing changes in movement variability during cumulative tackles in young elite rugby league players.

The aim of this study was to identify between-position (forwards vs. backs) differences in movement variability in cumulative tackle events training during both attacking and defensive roles. Eleven elite adolescent male rugby league players volunteered to participate in this study (mean ± SD, age; 18.5 ± 0.5 years, height; 179.5 ± 5.0 cm, body mass; 88.3 ± 13.0 kg). Participants performed a drill encompassing four blocks of six tackling (i.e. tackling an opponent) and six tackled (i.e. being tackled by an opponent while carrying a ball) events (i.e. 48 total tackles) while wearing a micro-technological inertial measurement unit (WIMU, Realtrack Systems, Spain). The acceleration data were used to calculate sample entropy (SampEn) to analyse the movement variability during tackles performance. In tackling actions SampEn showed significant between-position differences in block 1 (p = 0.0001) and block 2 (p = 0.0003). Significant between-block differences were observed in backs (block 1 vs 3, p = 0,0021; and block 1 vs 4, p = 0,0001) but not in forwards. When being tackled, SampEn showed significant between-position differences in block 1 (p = 0.0007) and block 3 (p = 0.0118). Significant between-block differences were only observed for backs in block 1 vs 4 (p = 0,0025). Movement variability shows a progressive reduction with cumulative tackle events, especially in backs and when in the defensive role (tackling). Forwards present lower movement variability values in all blocks, particularly in the first block, both in the attacking and defensive role. Entropy measures can be used by practitioners as an alternative tool to analyse the temporal structure of variability of tackle actions and quantify the load of these actions according to playing position.

Short-term effects of two different recovery strategies on muscle contractile properties in healthy active men: A randomised cross-over study.

The aim of this study was to compare the immediate effects of cold-water immersion (CWI) and hot-water immersion (HWI) versus passive resting after a fatigue-induced bout of exercise on the muscle contractile properties of the Vastus Medialis (VM). We conducted a randomised cross-over study involving 28 healthy active men where muscle contractile properties of the VM wer recorded using Tensiomyography (TMG) before and after CWI, HWI or passive resting and up to one-hour post-application. The main outcomes obtained were muscle displacement and velocity of deformation according to limb size (Dmr and Vdr). Our results showed a significant effect of time (F(3.9,405) =32.439; p <0.001; η2p =0.29) and the interaction between time and temperature (F(7.9,405) =5.814; p <0.001; η2p=0.13) on Dmr but no for temperature alone (F(2,81) =2.013; p =0.14; η2p=0.04) while for Vdr, both time (F(5.2,486) =23.068; p <0.001 η2p = 0.22) and temperature (F(2,81) =4.219; p = 0.018; η2p= 0.09) as well as the interaction (F(10.4,486) =7.784; p <0.001; η2p =0.16) were found significant. Compared to CWI, HWI increased Dmr post-application and Vdr both post-application as well as 15 and 45' thereafter. These findings suggest that applying HWI could be a valid alternative to CWI to promote muscle recovery.

Assessing the Reliability and Validity of Agility Testing in Team Sports: A Systematic Review.

ABSTRACT: Yepes, MM, Feliu, GM, Bishop, C, and Gonzalo-Skok, O. Assessing the reliability and validity of agility testing in team sports: A systematic review. J Strength Cond Res 36(7): 2035-2049, 2022-The aims of this systematic review were to (a) examine the reliability of the reactive agility tests and (b) analyze the discriminatory validity of the agility tests. A literature search was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We explored PubMed, SPORTDiscus, and Cochrane Plus databases looking for articles about agility in team sports. After filtering for article relevance, only 42 studies met the inclusion criteria; 37 of which assessed the reliability of agility tests and 22 assessing their validity. Reliability showed a high intraclass correlation coefficient (ICC) in almost all studies (range 0.79-0.99) with the exception of 2 studies. In addition, other studies also assessed the reliability of decision time (ICC = 0.95), movement time (ICC = 0.92), and decision accuracy (ICC = 0.74-0.93), all of which exhibited acceptable reliability. Furthermore, these data show high discriminatory validity, with higher performance level players being faster than lower performance level players (mean = 6.4%, range = 2.1-25.3%), with a faster decision time (mean = 23.2%, range = 10.2-48.0%) with the exception of 1 study, and better decision accuracy (mean = 9.3%, range = 2.5-21.0%). Thus, it can be concluded that reactive agility tests show good reliability and discriminatory validity. However, most agility tests occur in simple contexts whereby only 2 possible responses are possible. Therefore, future research should consider creating more specific and complex environments that challenge the cognitive process of high-level athletes.

The Influence of Functional Flywheel Resistance Training on Movement Variability and Movement Velocity in Elite Rugby Players.

The aim of this study was to identify the changes in movement variability and movement velocity during a six-week training period using a resistance horizontal forward-backward task without (NOBALL) or with (BALL) the constraint of catching and throwing a rugby ball in the forward phase. Eleven elite male rugby union players (mean ± SD: age 25.5 ± 2.0 years, height 1.83 ± 0.06 m, body mass 95 ± 18 kg, rugby practice 14 ± 3 years) performed eight repetitions of NOBALL and BALL conditions once a week in a rotational flywheel device. Velocity was recorded by an attached rotary encoder while acceleration data were used to calculate sample entropy (SampEn), multiscale entropy, and the complexity index. SampEn showed no significant decrease for NOBALL (ES = -0.64 ± 1.02) and significant decrease for BALL (ES = -1.71 ± 1.16; p < 0.007) conditions. Additionally, movement velocity showed a significant increase for NOBALL (ES = 1.02 ± 1.05; p < 0.047) and significant increase for BALL (ES = 1.25 ± 1.08; p < 0.025) between weeks 1 and 6. The complexity index showed higher levels of complexity in the BALL condition, specifically in the first three weeks. Movement velocity and complex dynamics were adapted to the constraints of the task after a four-week training period. Entropy measures seem a promising processing signal technique to identify when these exercise tasks should be changed.

Changes in physical demands between game quarters of U18 elite official basketball games.

PURPOSE: The aim of this study was to describe the physical demands during U18 elite basketball games according to the game quarter and to identify a smaller subset of variables and threshold scores that distinguish players' physical performance in each quarter. METHODS: Data was collected from ninety-four players who participated in the study (age: 17.4 ± 0.74 years; height: 199.0 ± 0.1 cm; body mass: 87.1 ± 13.1 kg) competing in the Euroleague Basketball Next Generation Tournament. Players' movements during the games were measured using a portable local positioning system (LPS) (WIMU PRO®, Realtrack Systems SL, Almería, Spain) and included relative distance (total distance / playing duration), relative distance in established speed zones, high-intensity running (18.1-24.0 km·h-1) and sprinting (> 24.1 km·h-1). player load, peak speed (km·h-1) and peak acceleration (m·s-2) number of total accelerations and total decelerations, high intensity accelerations (> 2 m·s-2) and decelerations (< -2 m·s-2). RESULTS: There was an overall decrease in distance covered, player load, number of high intensity accelerations and decelerations between the first and last quarter of the games in all playing positions. A classification tree analysis showed that the first quarter had much influence of distance covered (above 69.0 meters), distance covered <6.0 km·h-1 and accelerations (> 2 m·s-2), whereas the fourth quarter performance had much influence of distance covered (below 69.0) and distance covered 12.1-18.0 km·h-1. CONCLUSIONS: A significant reduction in physical demands occurs during basketball, especially between first and last quarter for players in all playing positions during basketball games of under 18 elite players.

Physical demands of elite basketball during an official U18 international tournament.

The aims of this study were (a) to compare players' physical demands between different playing positions in elite U18 basketball games and (b) to identify different clusters of performance. Data were collected from 94 male subjects (age: 17.4 ± 0.7 years), competing in a Euroleague Basketball Tournament. Guards covered a greater relative distance than centres and forwards (small to moderate effect). Forwards and guards had more peak accelerations, high accelerations and high decelerations than centres (moderate to large effects). A cluster analysis allowed to classify all cases into three different groups (Lower, Medium and Higher activity demands), containing 37.4%, 52.8% and 9.8% of the cases, respectively. The high accelerations, high decelerations, peak accelerations and total distance covered were the variables that most contributed to classify the players into the new groups. The percentage of cases distributed in the clusters according to playing position, game type (worst vs worst, mixed opposition, best vs best) and team were different. Centres have lower physical demands specially related with the number of accelerations and decelerations at high intensity and the peak acceleration when compared with guards. Each team has a different activity profile, that does not seem to influence the tournament outcome.

Structure of force variability during squats performed with an inertial flywheel device under stable versus unstable surfaces.

The use of unstable surfaces during resistance training has demonstrated a maintenance or reduction on force production. However, the use of unstable surface on force variability has not been assessed using non-linear methods that may be better suited to detect changes in movement variability throughout a given movement. Consequently, this study compared the use of stable vs unstable surfaces on force variability during bilateral squats performed with an inertial flywheel device (Eccoteck, Byomedic System SCP, Spain). Twenty healthy men (mean ±â€¯SD: age 22.9 ±â€¯2.9 years, height 1.81 ±â€¯0.7 m, body mass 76.4 ±â€¯7.6 kg and 1RM back squat 110.9 ±â€¯19.7 kg) with a minimum of four years in resistance training performed six sets of six repetitions of squats at maximal concentric effort with one minute rest between sets. Force output on the vertical axes was measured using a strain gauge and the results were processed using non-linear sample entropy (SampEn). Results showed no differences for any of the dependent variables between stable and unstable conditions. SampEn showed no differences between conditions (chi-squared = 0.048 P = 0.827), while Forcemean and SampEn presented a small correlation (r = 0.184; p < 0.01). No changes in entropy were found over the course of the series. Together, these results suggest that the structure of force variability between stable and unstable surfaces are similar. This lack of difference between surfaces may be due to postural and anticipatory adjustments. Consequently, by introducing unstable surfaces to the flywheel bilateral squat exercise, practitioners may not observe changes in Forcemean and force variability when compared to stable surface training suggesting that increased training volumes or intensity may be required during unstable environments to cause a desired training stimulus.

A Repeated Power Training Enhances Fatigue Resistance While Reducing Intraset Fluctuations.

Oliver, GS, Julio, TF, Moras, G, José Luis, AS, and Alberto, MV. A repeated power training enhances fatigue resistance while reducing intraset fluctuations. J Strength Cond Res 33(10): 2711-2721, 2019-The present study analyzed the effects of adding upper-body repeated power ability (RPA) training to habitual strength training sessions. Twenty young elite male basketball players were randomly allocated into a control group (CON, n = 10) or repeated power group (RPG, n = 10) and evaluated by 1 repetition maximum (1RM), incremental load, and RPA tests in the bench press exercise before and after a 7-week period and a 4-week cessation period. Repeated power group performed 1-3 blocks of 5 sets of 5 repetitions using the load that maximized power output with 30 seconds and 3 minute of passive recovery between sets and blocks, respectively. Between-group analysis showed substantial greater improvements in RPG compared with CON in: best set (APB), last set (APL), mean power over 5 sets (APM), percentage of decrement, fluctuation decrease during APL and RPA index (APLpost/APBpre) during the RPA test (effect size [ES] = 0.64-1.86), and 1RM (ES = 0.48) and average power at 80% of 1RM (ES = 1.11) in the incremental load test. The improvements of APB and APM were almost perfectly correlated. In conclusion, RPA training represents an effective method to mainly improve fatigue resistance together with the novel finding of a better consistency in performance (measured as reduced intraset power fluctuations) at the end of a dynamic repeated effort.

Entropy measures detect increased movement variability in resistance training when elite rugby players use the ball.

OBJECTIVES: This study described the variability in acceleration during a resistance training task, performed in horizontal inertial flywheels without (NOBALL) or with the constraint of catching and throwing a rugby ball (BALL). DESIGN AND METHODS: Twelve elite rugby players (mean±SD: age 25.6±3.0years, height 1.82±0.07m, weight 94.0±9.9kg) performed a resistance training task in both conditions (NOBALL AND BALL). Players had five minutes of a standardized warm-up, followed by two series of six repetitions of both conditions: at the first three repetitions the intensity was progressively increased while the last three were performed at maximal voluntary effort. Thereafter, the participants performed two series of eight repetitions from each condition for two days and in a random order, with a minimum of 10min between series. The structure of variability was analysed using non-linear measures of entropy. RESULTS: Mean changes (%; ±90% CL) of 4.64; ±3.1g for mean acceleration and 39.48; ±36.63a.u. for sample entropy indicated likely and very likely increase when in BALL condition. Multiscale entropy also showed higher unpredictability of acceleration under the BALL condition, especially at higher time scales. CONCLUSIONS: The application of match specific constraints in resistance training for rugby players elicit different amount of variability of body acceleration across multiple physiological time scales. Understanding the non-linear process inherent to the manipulation of resistance training variables with constraints and its motor adaptations may help coaches and trainers to enhance the effectiveness of physical training and, ultimately, better understand and maximize sports performance.

Eccentric-Overload Training in Team-Sport Functional Performance: Constant Bilateral Vertical Versus Variable Unilateral Multidirectional Movements.

PURPOSE: To analyze the effects of 2 different eccentric-overload training (EOT) programs, using a rotational conical pulley, on functional performance in team-sport players. A traditional movement paradigm (ie, squat) including several sets of 1 bilateral and vertical movement was compared with a novel paradigm including a different exercise in each set of unilateral and multi-directional movements. METHODS: Forty-eight amateur or semiprofessional team-sport players were randomly assigned to an EOT program including either the same bilateral vertical (CBV, n = 24) movement (squat) or different unilateral multidirectional (VUMD, n = 24) movements. Training programs consisted of 6 sets of 1 exercise (CBV) or 1 set of 6 exercises (VUMD) × 6-10 repetitions with 3 min of passive recovery between sets and exercises, biweekly for 8 wk. Functional-performance assessment included several change-of-direction (COD) tests, a 25-m linear-sprint test, unilateral multidirectional jumping tests (ie, lateral, horizontal, and vertical), and a bilateral vertical-jump test. RESULTS: Within-group analysis showed substantial improvements in all tests in both groups, with VUMD showing more robust adaptations in pooled COD tests and lateral/horizontal jumping, whereas the opposite occurred in CBV respecting linear sprinting and vertical jumping. Between-groups analyses showed substantially better results in lateral jumps (ES = 0.21), left-leg horizontal jump (ES = 0.35), and 10-m COD with right leg (ES = 0.42) in VUMD than in CBV. In contrast, left-leg countermovement jump (ES = 0.26) was possibly better in CBV than in VUMD. CONCLUSIONS: Eight weeks of EOT induced substantial improvements in functional-performance tests, although the force-vector application may play a key role to develop different and specific functional adaptations.

W5″ Test: A simple method for measuring mean power output in the bench press exercise.

The aims of the present study were to assess the validity and reliability of a novel simple test [Five Seconds Power Test (W5″ Test)] for estimating the mean power output during the bench press exercise at different loads, and its sensitivity to detect training-induced changes. Thirty trained young men completed as many repetitions as possible in a time of ≈5 s at 25%, 45%, 65% and 85% of one-repetition maximum (1RM) in two test sessions separated by four days. The number of repetitions, linear displacement of the bar and time needed to complete the test were recorded by two independent testers, and a linear encoder was used as the criterion measure. For each load, the mean power output was calculated in the W5″ Test as mechanical work per time unit and compared with that obtained from the linear encoder. Subsequently, 20 additional subjects (10 training group vs. 10 control group) were assessed before and after completing a seven-week training programme designed to improve maximal power. Results showed that both assessment methods correlated highly in estimating mean power output at different loads (r range: 0.86-0.94; p < .01) and detecting training-induced changes (R(2): 0.78). Good to excellent intra-tester (intraclass correlation coefficient (ICC) range: 0.81-0.97) and excellent inter-tester (ICC range: 0.96-0.99; coefficient of variation range: 2.4-4.1%) reliability was found for all loads. The W5″ Test was shown to be a valid, reliable and sensitive method for measuring mean power output during the bench press exercise in subjects who have previous resistance training experience.

Force Outputs during Squats Performed Using a Rotational Inertia Device under Stable versus Unstable Conditions with Different Loads.

The purpose of the study was to compare the force outputs achieved during a squat exercise using a rotational inertia device in stable versus unstable conditions with different loads and in concentric and eccentric phases. Thirteen male athletes (mean ± SD: age 23.7 ± 3.0 years, height 1.80 ± 0.08 m, body mass 77.4 ± 7.9 kg) were assessed while squatting, performing one set of three repetitions with four different loads under stable and unstable conditions at maximum concentric effort. Overall, there were no significant differences between the stable and unstable conditions at each of the loads for any of the dependent variables. Mean force showed significant differences between some of the loads in stable and unstable conditions (P < 0.010) and peak force output differed between all loads for each condition (P < 0.045). Mean force outputs were greater in the concentric than in the eccentric phase under both conditions and with all loads (P < 0.001). There were no significant differences in peak force between concentric and eccentric phases at any load in either stable or unstable conditions. In conclusion, squatting with a rotational inertia device allowed the generation of similar force outputs under stable and unstable conditions at each of the four loads. The study also provides empirical evidence of the different force outputs achieved by adjusting load conditions on the rotational inertia device when performing squats, especially in the case of peak force. Concentric force outputs were significantly higher than eccentric outputs, except for peak force under both conditions. These findings support the use of the rotational inertia device to train the squatting exercise under unstable conditions for strength and conditioning trainers. The device could also be included in injury prevention programs for muscle lesions and ankle and knee joint injuries.

Force production during squats performed with a rotational resistance device under stable versus unstable conditions.

[Purpose] Force production during a squat action on a rotational resistance device (RRD) under stable and unstable conditions. [Subjects and Methods] Twenty-one healthy males were asked to perform six sets of six repetitions of squats on an RRD on either stable or unstable surfaces. The stable and unstable sets were performed on different days. Muscular outputs were obtained from a linear encoder and a strain gauge fixed to a vest. [Results] Overall, the results showed no significant differences for any of the dependent variables across exercise modes. Forcemean outputs were higher in the concentric phase than in the eccentric phase for each condition, but there were no differences in velocity, time or displacement. The forcepeak was similar in the eccentric and concentric phases of movement under both stable and unstable conditions. There were no significant differences in forcemean between sets per condition or between conditions. [Conclusion] These results suggest that performing squats with a RRD achieves similar forcemean and forcepeak under stable and unstable conditions. The forcepeak produced is also similar in concentric and eccentric phases.

Cambios en la arquitectura muscular y en la velocidad de ejecución de sentadillas en VersaPulley en condiciones estables e inestables en jugadores junior de baloncesto de élite durante una temporada / Mudanças na arquitetura muscular e agachamentos velocidade de execução em VersaPulley em condições estáveis e instáveis em juniores jogadores de basquete de elite durante a temporada / Changes in muscular architecture and execution velocity during squats performed using the VersaPulley under stable and unstable conditions in junior elite basketball players

Los objetivos del presente estudio fueron: a) monitorizar y comparar la velocidadpico de ejecución de sentadillas con VersaPulley (VP) en condiciones estables (CE) y condiciones inestables (CI) en jugadores junior de baloncesto de élite durante una temporada y b) evaluar los cambios en la arquitectura muscular (AM). Siete jugadores junior de baloncesto realizaron el entrenamiento técnico-táctico y de acondicionamiento físico de la temporada (16 horas semanales) incluyendo entrenamiento de fuerza mediante sentadillas con VP en CE y CI. Durante la temporada se evaluó la velocidadpico de ejecución de las sentadillas mediante el sistema T-FORCE. Además, cada 3 meses se valoró la AM del vasto lateral mediante ultrasonidos. Los resultados no mostraron diferencias significativas en la velocidadpico al realizar sentadillas entre ambas condiciones en ningún momento de la temporada, aumentando un 17% en CE y un 23% en CI (p<0,01). El grosor muscular (p= 0,009) y el ángulo de peneación (p<0,05) aumentaron mientras que la longitud de los fascículos no experimentó cambios significativos. El entrenamiento regular de baloncesto y el entrenamiento de fuerza incluyendo sentadillas con VP en CE y CI generaron niveles similares de velocidadpico en ambas condiciones en jugadores de baloncesto júnior de élite. La velocidadpico aumentó tanto en CE como en CI durante la temporada. Además, se produjeron cambios en la AM (AU)

Os objetivos do estudo em questão foram: a) monitorar e comparar a velocidade máxima de execução de agachamento no VersaPulley (VP) em condições estáveis (CE) e condições instáveis (CI) em jogadores juvenis de basquete de elite durante uma temporada e b) avaliar as mudanças na arquitetuta muscular (AM). Sete jogadores juvenis de basquete realizaram o treinamento técnico-tatico e de condicionamento físico da temporada (16 horas semanais) incluindo treinamento de forca através de agachamentos com VP em CE e CI. Durante a temporada monitorizou-se a velocidade máxima de execução dos agachamentos através do sistema T-FORCE. Além disso, a cada 3 meses avaliou-se a AM do vasto lateral através de Ultra-som. Os resultados nao mostraram diferenças significativas na velocidade máxima ao realizar agachamentos entre ambas condições em nenhum momento da temporada, aumentando um 17% em CE e um 23% em CI (p<0,01). A grossura muscular (p=0,009) e o ângulo de penação (p<0,05) aumentaram enquanto que a longitude dos fascículos nao demonstrou mudanças sinificativas. O treinamento normal de basquete e o treinamento de força incluindo agachamentos com VP em CE e CI geraram níveis similares de velocidade máxima em ambas condições nos jogadores de basquete juvenis de elite. A velocidade maxima aumentou tanto em CE como em CI durante a temporada. Além disso, produziu-se mudanças na AM (AU)

The purposes of the present study were to: a) monitor and compare velocitypeak when performing squats with VersaPulley (VP) on stable conditions (CE) and on unstable conditions (CI) in elite junior basketball players during a season and b) assess the changes in muscle architecture (AM). Seven junior basketball players performed the technical-tactical training and the physical fitness of the season (16 weekly hours) adding extra strength training performing squats with the VP under CE and CI. Velocitypeak when performing the squats was assessed during the season through T-FORCE system. Moreover, every 3 months the AM of the vastus lateralis was assessed. Results indicated that velocitypeak did not show significant differences when performing squats under both conditions during the season. Velocitypeak increased 17% under CE and 23% under CI (p< 0.05) increased whilst the fascicle length did not show significant differences. The regular basketball training and the strength training, including squats performed with VP under CE and CI, increased a long de season in a basketball elite junior players. Moreover, we founded changes in AM (AU)

The influence of serve characteristics on performance in men's and women's high-standard beach volleyball.

The precise influence of serve type and serve ball speed on beach volleyball performance is unclear. We examined the relationship between serve type and speed and their effectiveness during the 2008 Men's and Women's Open World Tour Tournament. Three hundred and seventy-eight and 375 serves performed by men and women respectively from the main draw tournament were analysed. Serve speed was recorded using a radar gun. Two expert observers recorded serve speed, serve mode, serve effectiveness and rally outcome. There was no relationship between serve speed and its effectiveness for men (r = -0.047, P > 0.05) and for women (r = -0.048, P > 0.05). However, there was a relationship between serve ball speed and its effectiveness both for men and women, when speed was categorised into three groups. There was a better balance between negative and positive outcomes at medium speeds for men and at low and high speeds for women. There was a relationship between ranking and serve ball speed only for women and between ranking and type of serve for both genders. There was no relationship between rally outcome and serve effectiveness. The combination of high ball speed and jump serve is characteristic of high ranking women but not of men.

Children's time production for concurrent nontemporal motor tasks.

An internal clock model has often been used to explain disruptions in timing production that occur when temporal and nontemporal tasks are performed simultaneously. In this study, participants' ability to walk 8 m in 8 sec. while executing various secondary concurrent nontemporal tasks was assessed for 16 children enrolled in sports at school. Children participated in six trials under five randomized task conditions involving different coordinative and cognitive workloads. The duration of timing production increased as the attention requirements or cognitive demands placed upon the completion of the task increased. However, participants also showed learning of timing over the six trials. Significant differences were found between the timing task and the concurrent nontemporal tasks depending on the difficulty and cognitive load of the secondary tasks. Results are discussed using attention models of time estimation and production.

Inter-rater reliability of muscle contractile property measurements using non-invasive tensiomyography.

Tensiomyography (TMG) is a relatively novel technique to assess muscle mechanical response based on radial muscle belly displacement consecutive to a single electrical stimulus. Although intra-session reliability has been found to be good, inter-rater reliability and the influence of sensor repositioning and electrodes placement on TMG measurements is unknown. The purpose of this study was to analyze the inter-rater reliability of vastus medialis muscle contractile property measurements obtained with TMG as well as the effect of inter-electrode distance (IED). Five contractile parameters were analyzed from vastus medialis muscle belly displacement-time curves: maximal displacement (Dm), contraction time (Tc), sustain time (Ts), delay time (Td), and half-relaxation time (Tr). The inter-rater reliability and IED effect on these measurements were evaluated in 18 subjects. Intra-class correlation coefficients, standard errors of measurement, Bland and Altman systematic bias and random error as well as coefficient of variations were used as measures of reliability. Overall, a good to excellent inter-rater reliability was found for all contractile parameters, except Tr, which showed insufficient reliability. Alterations in IED significantly affected Dm with a trend for all the other parameters. The present results legitimate the use of TMG for the assessment of vastus medialis muscle contractile properties, particularly for Dm and Tc. It is recommended to avoid Tr quantification and IED modifications during multiple TMG measurements.

A vibratory bar for upper body: feasibility and acute effects on EMGrms activity.

The purpose of this study was to determine the feasibility of a purpose-designed vibratory bar (VB) as a potential vibration training device and thereafter to assess its effects on upper-body muscles' electromyographic (EMG) activity during vibration. During session 1, 16 physically active males held the VB during the bench press exercise in an isometric extended position (EP) in the following vibration conditions selected in the inverter (i): no vibration (0), 20, 30, 40, and 50 Hzi. Maximal acceleration (Accmax), frequency (Freq), and peak-to-peak amplitude (Ampp-p) obtained at the center (C) and at the end (E) of the VB were assessed using an accelerometer. During session 2, EMGrms of the triceps, deltoid, and pectoralis major were recorded in EP and isometric flexion position (FP) at 0, 25, and 45 Hzi. The Accmax, Freq, and Ampp-p values ranged from 37.4 to 96.4 mxs, 18.5 to 30.8 Hz, and 4.6 to 6.1 mm, respectively. The accelerometer's position had a significant effect on the Accmax and Ampp-p. All Freq obtained at C and E were different (p < 0.001) to the Freqi. An increase (p < 0.05) in EMGrms was observed in both vibration conditions compared with 0 Hzi, except during 25Hzi for deltoid and pectoralis muscle in FP. Although no significant differences were found in any of the muscles between 45 Hzi and 25Hzi, the highest EMGrms was elicited at 45Hzi. Although the registered VBs' parameters seem appropriate for vibration training, the frequency in the FP should be higher than 25 Hzi to induce significant increases in EMGrms in deltoid and pectoralis muscles. The use of a vibratory bar may be a suitable system to simultaneously stimulate upper-body muscles.

Effect of acute and chronic whole-body vibration exercise on serum insulin-like growth factor-1 levels in women with fibromyalgia.

OBJECTIVE: The purpose of this study was to investigate the effect of acute and chronic whole-body vibration exercise on serum insulin-like growth factor-1 (IGF-1) levels in women with fibromyalgia. METHODS: A randomized controlled two-factor mixed experimental design was used. Twenty-four women with fibromyalgia (age +/- standard error of the mean, 54.95 +/- 2.03) were randomized into the vibration group or the control group. The vibration group underwent a protocol of static and dynamic tasks with whole-body vibration exercise twice a week for a total of six weeks, whereas the control group performed the same protocol without vibratory stimulus. Both groups continued their usual pharmacological treatment. Serum IGF-1 levels were determined using enzyme-linked immunosorbent assay (ELISA). To test the effects of long-term whole-body vibration exercise, serum IGF-1 measurements were taken at baseline and at weeks 1, 3, and 6 of the intervention. To test the short-term effects, at week 1, serum IGF-1 measurements were taken before and immediately following a session of whole-body vibration exercise. RESULTS: Treatment adherence was 93% in the vibration group and 92% in the control group. None of the subjects dropped out of the study. There was an absence of change in IGF-1 at week 1 and week 6 of whole-body vibration exercise. CONCLUSION: Results show no change in serum IGF-1 levels in women with fibromyalgia undergoing whole-body vibration exercise. Although high-intensity exercise and whole-body vibration exercise have been shown to increase serum IGF-1 in healthy individuals, the effectiveness of whole-body vibration exercise as a strategy to produce improvements in serum IGF-1 levels in women with fibromyalgia could not be demonstrated.

A metronome for controlling the mean velocity during the bench press exercise.

Lifting velocity may have a great impact on strength training-induced adaptations. The purpose of this study was to validate a method including a metronome and a measurement tape as inexpensive tools for the estimation of mean lifting velocity during the bench press exercise. Fifteen subjects participated in this study. After determining their one repetition maximum (1RM) load, we estimated the maximum metronome rhythm (R) that each subject could maintain in the concentric phase for loads of 40 and 60% of 1RM. To estimate R, the 3 repetitions with highest concentric power, as measured by means of a linear encoder, were selected, and their average duration was calculated and converted to lifting rhythm in beats per minute (bpm) for each subject. The range of motion was measured using a regular tape and kept constant during all exercises. Subjects were instructed to begin with the barbell at arm lengths and lower it in correspondence with the metronome beep. They subsequently performed 5 repetitions at 3 different rhythms relative to R (50, 70, and 90% R) for each training load (40 and 60% of 1RM). A linear encoder was attached to the bar and used as a criterion to measure the vertical displacement over time. For each rhythm, the mean velocity was calculated with the metronome (time) and the reference distance and compared with that recorded by the linear encoder. The SEM for velocity between both testing methods ranged from 0.02 to 0.05 m.s (coefficient of variation, 4.0-6.4%; Pearson's correlation, 0.8-0.95). The present results showed that the use of a metronome and a measurement tape may be a valid method to estimate the mean velocity of execution during the bench press exercise. This simple method could help coaches and athletes achieve their strength training goals, which are partly determined by lifting velocity.