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1.
Eur J Appl Physiol ; 121(12): 3539-3549, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34536112

RESUMEN

PURPOSE: This study examined the effect of graded hypoxia during exhaustive intermittent cycling on subsequent exercise performance and neuromuscular fatigue characteristics in normoxia. METHODS: Fifteen well-trained cyclists performed an exhaustive intermittent cycling exercise (EICE 1; 15 s at 30% of anaerobic power reserve interspersed with 45 s of passive recovery) at sea level (SL; FiO2 ~ 0.21), moderate (MH; FiO2 ~ 0.16) and severe hypoxia (SH; FiO2 ~ 0.12). This was followed, after 30 min of passive recovery in normoxia, by an identical exercise bout in normoxia (EICE 2). Neuromuscular function of the knee extensors was assessed at baseline, after EICE 1 (post-EICE 1), and EICE 2 (post-EICE 2). RESULTS: The number of efforts completed decreased with increasing hypoxic severity during EICE 1 (SL: 39 ± 30, MH: 22 ± 13, SH: 13 ± 6; p ≤ 0.02), whereas there was no difference between conditions during EICE 2 (SL: 16 ± 9, MH: 20 ± 14, SH: 24 ± 17; p ≥ 0.09). Maximal torque (p = 0.007), peripheral (p = 0.02) and cortical voluntary activation (p < 0.001), and twitch torque (p < 0.001) decreased from baseline to post-EICE 1. Overall, there were no significant difference in any neuromuscular parameters from post-EICE 1 to post-EICE 2 (p ≥ 0.08). CONCLUSION: Increasing hypoxia severity during exhaustive intermittent cycling hampered exercise capacity, but did not influence performance and associated neuromuscular responses during a subsequent bout of exercise in normoxia performed after 30 min of rest.


Asunto(s)
Rendimiento Atlético/fisiología , Ciclismo/fisiología , Hipoxia/fisiopatología , Fatiga Muscular/fisiología , Músculo Esquelético/fisiología , Adulto , Prueba de Esfuerzo , Humanos , Masculino , Contracción Muscular/fisiología , Torque
2.
Scand J Med Sci Sports ; 28(10): 2216-2225, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-29797592

RESUMEN

Scheduling eccentric-based injury prevention programs (IPP) during the common 6-day micro-cycle in soccer is challenged by recovery and tapering phases. This study profiled muscle damage, neuromuscular performance, and perceptual responses to a lower limb eccentric-based IPP administered 1 (MD+1) vs 3 days (MD+3) postmatch. A total of 18 semi-professional players were monitored daily during 3 in-season 6-day micro-cycles, including weekly competitive fixtures. Capillary creatine kinase concentration (CK), posterior lower limb isometric peak force (PF), counter-movement jump (CMJ) performance, and muscle soreness were assessed 24 hours prior to match-day (baseline), and every 24 hours up to 120 hours postmatch. The IPP consisted of lunges, single stiff leg dead-lifts, single leg-squats, and Nordic hamstring exercises. Performing the IPP on MD+1 attenuated the decline in CK normally observed following match play (CON: 142%; MD+3: 166%; small differences). When IPP was delivered on MD+3, CK was higher vs CON and MD+1 trials on both MD+4 (MD+3: 260%; CON: 146%; MD+1: 151%; moderate differences) and MD+5 (MD+3: 209%; CON: 125%; MD+1: 127%; small differences). Soreness ratings were not exacerbated when the IPP was delivered on MD+1, but when prescribed on MD+3, hamstring soreness ratings remained higher on MD+4 and MD+5 (small differences). No between-trial differences were observed for PF and CMJ. Administering the IPP in the middle of the micro-cycle (MD+3) increased measures of muscle damage and soreness, which remained elevated on the day prior to the next match (MD+5). Accordingly, IPP should be scheduled early in the micro-cycle, to avoid compromising preparation for the following match.


Asunto(s)
Traumatismos en Atletas/prevención & control , Terapia por Ejercicio , Extremidad Inferior/lesiones , Fútbol/lesiones , Factores de Tiempo , Adulto , Creatina Quinasa/sangre , Estudios Cruzados , Humanos , Extremidad Inferior/fisiología , Fuerza Muscular , Músculo Esquelético/lesiones , Músculo Esquelético/fisiología , Mialgia , Adulto Joven
3.
Int J Sports Med ; 36(5): 351-6, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25429552

RESUMEN

The aim of the present study was to examine whether monthly resting heart rate (HR), HR variability (HRV) and psychometric measures can be used to monitor changes in physical performance in highly-trained adolescent handball players. Data were collected in 37 adolescent players (training 10±2.1 h.wk(-1)) on 11 occasions from September to May during the in-season period, and included an estimation of training status (resting HR and HRV, the profile of mood state (POMS) questionnaire), and 3 physical performance tests (a 10-m sprint, a counter movement jump and a graded aerobic intermittent test, 30-15 Intermittent Fitness Test). The sensitivity of HR and psychometric measures to changes in physical performance was poor (< 20%), irrespective of the training status markers and the performance measures. The specificity was however strong (> 75%), irrespective of the markers and the performance measures. Finally, the difference in physical performance between players with better vs. worse estimated training status were all almost certainly trivial. The present results highlight the limitation of monthly measures of resting HR, HRV and perceived mood and fatigue for predicting in-season changes in physical performance in highly-trained adolescent handball players. This suggests that more frequent monitoring might be required, and/or that other markers might need to be considered.


Asunto(s)
Rendimiento Atlético/fisiología , Rendimiento Atlético/psicología , Frecuencia Cardíaca/fisiología , Psicometría , Adolescente , Afecto , Fatiga/fisiopatología , Femenino , Humanos , Extremidad Inferior/fisiología , Masculino , Fuerza Muscular/fisiología , Carrera/fisiología , Sensibilidad y Especificidad , Deportes/fisiología , Deportes/psicología
4.
Int J Sports Med ; 36(14): 1149-55, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26393813

RESUMEN

The aim of the present study was to examine the validity and reliability of metabolic power (P) estimated from locomotor demands during soccer-specific drills. 14 highly-trained soccer players performed a soccer-specific circuit with the ball (3×1-min bouts, interspersed with 30-s passive recovery) on 2 different occasions. Locomotor activity was monitored with 4-Hz GPSs, while oxygen update (VO2) was collected with a portable gas analyzer. P was calculated using either net VO2 responses and traditional calorimetry principles (PVO2, W.kg(-1)) or locomotor demands (PGPS, W.kg(-1)). Distance covered into different speed, acceleration and P zones was recorded. While PGPS was 29±10% lower than PVO2 (d<- 3) during the exercise bouts, it was 85±7% lower (d<- 8) during recovery phases. The typical error between PGPS vs. PVO2 was moderate: 19.8%, 90% confidence limits: (18.4;21.6). The correlation between both estimates of P was small: 0.24 (0.14;0.33). Very large day-to-day variations were observed for acceleration, deceleration and > 20 W.kg(-1) distances (all CVs > 50%), while average Po2 and PGPS showed CVs < 10%. ICC ranged from very low- (acceleration and > 20 W.kg(-1) distances) to-very high (PVO2). PGPS largely underestimates the energy demands of soccer-specific drills, especially during the recovery phases. The poor reliability of PGPS >20 W.kg(-1) questions its value for monitoring purposes in soccer.


Asunto(s)
Metabolismo Energético , Carrera/fisiología , Fútbol/fisiología , Aceleración , Sistemas de Información Geográfica , Humanos , Consumo de Oxígeno , Reproducibilidad de los Resultados , Estudios de Tiempo y Movimiento
5.
Int J Sports Med ; 35(8): 676-83, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-24595813

RESUMEN

The purpose of this study was to investigate changes in post-exercise heart rate recovery (HRR) and heart rate variability (HRV) during an overload-tapering paradigm in marathon runners and examine their relationship with running performance. 9 male runners followed a training program composed of 3 weeks of overload followed by 3 weeks of tapering (-33 ± 7%). Before and after overload and during tapering they performed an exhaustive running test (T(lim)). At the end of this test, HRR variables (e.g. HRR during the first 60 s; HRR(60 s)) and vagal-related HRV indices (e.g. RMSSD(5-10 min)) were examined. T(lim) did not change during the overload training phase (603 ± 105 vs. 614 ± 132 s; P = 0.992), but increased (727 ± 185 s; P = 0.035) during the second week of tapering. Compared with overload, RMSSD(5-10 min) (7.6 ± 3.3 vs. 8.6 ± 2.9 ms; P = 0.045) was reduced after the 2(nd) week of tapering. During tapering, the improvements in T(lim) were negatively correlated with the change in HRR(60 s) (r = -0.84; P = 0.005) but not RMSSD(5-10 min) (r = -0.21; P = 0.59). A slower HRR during marathon tapering may be indicative of improved performance. In contrast, the monitoring of changes in HRV as measured in the present study (i.e. after exercise on a single day), may have little or no additive value.


Asunto(s)
Frecuencia Cardíaca/fisiología , Sistema Nervioso Parasimpático/fisiología , Educación y Entrenamiento Físico/métodos , Resistencia Física/fisiología , Carrera/fisiología , Adulto , Humanos , Masculino , Consumo de Oxígeno
6.
Int J Sports Med ; 35(6): 494-504, 2014 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-24203798

RESUMEN

To examine the effects of body size on locomotor performance, 807 15-year-old French and 64 Qatari soccer players participated in the present study. They performed a 40-m sprint and an incremental running test to assess maximal sprinting (MSS) and aerobic speeds, respectively. French players were advanced in maturity, taller, heavier, faster and fitter than their Qatari counterparts (e.g., Cohen's d=+1.3 and + 0.5 for body mass and MSS). However, when adjusted for body mass (BM), Qatari players had possibly greater MSS than French players (d=+0.2). A relative age effect was observed within both countries, with the players born in the first quarter of the year being taller, heavier and faster that those born during the fourth quarter (e.g., d=+0.2 for MSS in French players). When directly adjusted for BM, these MSS differences remained (d=+0.2). Finally, in both countries, players selected in National teams were taller, heavier, faster and fitter than their non-selected counterparts (e.g., d=+0.6 for MSS in French players), even after adjustments for body size (d=+0.5). Differences in locomotor performances between players with different phenotypes are likely mediated by differences in body size. However, when considering more homogeneous player groups, body dimensions are unlikely to substantially explain the superior locomotor performances of older and/or international players.


Asunto(s)
Rendimiento Atlético/fisiología , Tamaño Corporal/fisiología , Carrera/fisiología , Fútbol/fisiología , Adolescente , Factores de Edad , Índice de Masa Corporal , Prueba de Esfuerzo , Humanos , Masculino , Maduración Sexual
7.
Scand J Med Sci Sports ; 23(3): e185-93, 2013 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-23362832

RESUMEN

This study examined the influence of muscle deoxygenation and reoxygenation on repeated-sprint performance via manipulation of O2 delivery. Fourteen team-sport players performed 10 10-s sprints (30-s recovery) under normoxic (NM: FI O2 0.21) and acute hypoxic (HY: FI O2 0.13) conditions in a randomized, single-blind fashion and crossover design. Mechanical work was calculated and arterial O2 saturation (Sp O2 ) was estimated via pulse oximetry for every sprint. Muscle deoxyhemoglobin concentration ([HHb]) was monitored continuously by near-infrared spectroscopy. Differences between NM and HY data were analyzed for practical significance using magnitude-based inferences. HY reduced Sp O2 (-10.7 ± 1.9%, with chances to observe a higher/similar/lower value in HY of 0/0/100%) and mechanical work (-8.2 ± 2.1%; 0/0/100%). Muscle deoxygenation increased during sprints in both environments, but was almost certainly higher in HY (12.5 ± 3.1%, 100/0/0%). Between-sprint muscle reoxygenation was likely more attenuated in HY (-11.1 ± 11.9%; 2/7/91%). The impairment in mechanical work in HY was very largely correlated with HY-induced attenuation in muscle reoxygenation (r = 0.78, 90% confidence limits: 0.49; 0.91). Repeated-sprint performance is related, in part, to muscle reoxygenation capacity during recovery periods. These results extend previous findings that muscle O2 availability is important for prolonged repeated-sprint performance, in particular when the exercise is taken in hypoxia.


Asunto(s)
Rendimiento Atlético/fisiología , Hipoxia/sangre , Oxígeno/sangre , Músculo Cuádriceps/metabolismo , Carrera/fisiología , Adulto , Estudios Cruzados , Hemoglobinas/metabolismo , Humanos , Hipoxia/metabolismo , Masculino , Oximetría , Oxígeno/metabolismo , Esfuerzo Físico/fisiología , Descanso/fisiología , Grosor de los Pliegues Cutáneos , Adulto Joven
8.
Br J Sports Med ; 47 Suppl 1: i59-69, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-24282209

RESUMEN

OBJECTIVES: To examine with a parallel group study design the performance and physiological responses to a 14-day off-season 'live high-train low in the heat' training camp in elite football players. METHODS: Seventeen professional Australian Rules Football players participated in outdoor football-specific skills (32 ± 1°C, 11.5 h) and indoor strength (23 ± 1°C, 9.3 h) sessions and slept (12 nights) and cycled indoors (4.3 h) in either normal air (NORM, n=8) or normobaric hypoxia (14 ± 1 h/day, FiO2 15.2-14.3%, corresponding to a simulated altitude of 2500-3000 m, hypoxic (HYP), n=9). They completed the Yo-Yo Intermittent Recovery level 2 (Yo-YoIR2) in temperate conditions (23 ± 1°C, normal air) precamp (Pre) and postcamp (Post). Plasma volume (PV) and haemoglobin mass (Hb(mass)) were measured at similar times and 4 weeks postcamp (4WPost). Sweat sodium concentration ((Na(+))(sweat)) was measured Pre and Post during a heat-response test (44°C). RESULTS: Both groups showed very large improvements in Yo-YoIR2 at Post (+44%; 90% CL 38, 50), with no between-group differences in the changes (-1%; -9, 9). Postcamp, large changes in PV (+5.6%; -1.8, 5.6) and (Na(+))sweat (-29%; -37, -19) were observed in both groups, while Hb(mass) only moderately increased in HYP (+2.6%; 0.5, 4.5). At 4WPost, there was a likely slightly greater increase in Hb(mass) (+4.6%; 0.0, 9.3) and PV (+6%; -5, 18, unclear) in HYP than in NORM. CONCLUSIONS: The combination of heat and hypoxic exposure during sleep/training might offer a promising 'conditioning cocktail' in team sports.


Asunto(s)
Altitud , Fútbol Americano/fisiología , Aclimatación/fisiología , Rendimiento Atlético/fisiología , Presión Atmosférica , Australia , Volumen Sanguíneo/fisiología , Ejercicio Físico/fisiología , Hemoglobinas/metabolismo , Calor , Humanos , Hipoxia/fisiopatología , Carrera/fisiología , Sueño/fisiología
9.
Int J Sports Med ; 34(10): 924-30, 2013 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-23740343

RESUMEN

The aim of the present study was to examine the respective importance of locomotor profile and muscle oxygen uptake (mV(˙)O2) recovery on repeated-sprint ability (RSA) and overall repeated-sprint performance. 11 sprint- (STR) and 10 middle-distance-trained (MDTR) athletes (20.8±4.0 yr) performed an incremental test and a 40-to-50-m sprint to estimate their maximal aerobic (MAS) and sprinting (MSS) speeds. They also performed 6×30-m sprints, departing every 30 s, where mean (RS(mean)) sprint time was calculated. Muscle oxygenation (Near-infrared spectroscopy, NIRS, [Hb(diff)]) was measured for ~ 4 min post test. The mean response time of [Hb(diff)]-mV(˙)O2 recovery (monoexponential curve fitting, MRT[Hb(diff)]-mV(˙)O2) was calculated. Compared with MDTR, STR presented faster MSS (+11.4±6.7%, with 99% chances to observe a substantially greater value) and RS(mean) (-3.7±5.4%, 78%), but slower MAS (-15.8±8.0%, 100%) and MRT[Hb(diff)]-mV(˙)O2 (+46.2±31.7%, 96%). RS(mean) was largely correlated with MSS [r=-0.83 (90%CL, -0.92;-0.67)], but neither with MAS [r=-0.12 (-0.47;0.25)] nor MRT[Hb(diff)]-mV(˙)O2 [r=-0.27(-0.58;0.11)]. RS(mean) adjusted for MSS (which indirectly reflects RSA) was largely correlated with both MAS [r=0.51(0.18;0.74)] and MRT[Hb(diff)]-mV(˙)O2 [r=0.53(0.20;0.75)]. While a fast mV(˙)O2 recovery is associated with an improved RSA, MSS remains of primary importance for overall repeated-sprint performance (i.e., RS(mean)).


Asunto(s)
Rendimiento Atlético/fisiología , Músculo Esquelético/fisiología , Consumo de Oxígeno/fisiología , Carrera/fisiología , Adolescente , Adulto , Femenino , Humanos , Cinética , Masculino , Espectroscopía Infrarroja Corta , Adulto Joven
10.
Int J Sports Med ; 34(1): 40-8, 2013 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-22895872

RESUMEN

The aim of this study was to examine in highly-trained young soccer players whether substantial changes in either maximal sprinting speed (MSS) or maximal aerobic speed (as inferred from peak incremental test speed, V(Vam-Eval)) can affect repeated high-intensity running during games. Data from 33 players (14.5±1.3 years), who presented substantial changes in either MSS or V(Vam-Eval) throughout 2 consecutive testing periods (~3 months) were included in the final analysis. For each player, time-motion analyses were performed using a global positioning system (1-Hz) during 2-10 international club games played within 1-2 months from/to each testing period of interest (n for game analyzed=109, player-games=393, games per player per period=4±2). Sprint activities were defined as at least a 1-s run at intensities higher than 61% of individual MSS. Repeated-sprint sequences (RSS) were defined as a minimum of 2 consecutive sprints interspersed with a maximum of 60 s of recovery. Improvements in both MSS and V(Vam-Eval) were likely associated with a decreased RSS occurrence, but in some positions only (e. g., - 24% vs. - 3% for improvements in MSS in strikers vs. midfielders, respectively). The changes in the number of sprints per RSS were less clear but also position-dependent, e. g., +7 to +12% for full-backs and wingers, - 5 to - 7% for centre-backs and midfielders. In developing soccer players, changes in repeated-sprint activity during games do not necessarily match those in physical fitness. Game tactical and strategic requirements are likely to modulate on-field players' activity patterns independently (at least partially) of players' physical capacities.


Asunto(s)
Rendimiento Atlético/fisiología , Aptitud Física/fisiología , Carrera/fisiología , Fútbol/fisiología , Adolescente , Atletas , Sistemas de Información Geográfica , Humanos , Masculino
11.
Int J Sports Med ; 34(7): 637-45, 2013 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-23526593

RESUMEN

The reliability of near infrared spectroscopy derived tissue oxygenation index (TOI) and total haemoglobin concentration (tHb) were examined during continuous (CR) and interval (INT) running. In a repeated measures design, 10 subjects twice performed 30 min of CR at 70% of their peak treadmill velocity, followed by 10 bouts of INT at 100%. Between trial reliability of mean and amplitude changes in TOI and tHb during CR were determined. Muscle de-oxygenation and re-oxygenation rates during INT were calculated using 3 analytical methods; i) linear modelling, ii) minimum and maximum values during work/rest intervals, and iii) mean values during work/rest intervals. Reliability was assessed using coefficient of variation (CV; %). During CR, mean TOI was more reliable (3.5%) compared with TOI amplitude change (34.7%), while mean tHb (12%) was similar to both absolute (9.2%) and relative (10.2%) amplitude changes. During INT, de-oxygenation rates analysed via linear modelling produced the lowest CV (7.2%), while analysis using min-max values produced the lowest CV (9.3%) for re-oxygenation rates. In conclusion, while the variables demonstrated CVs lower than reported changes in training-induced adaptations and/or differences between athletes and controls (23- 450%), practitioners are encouraged to consider the advantages/disadvantages of each method when performing their analysis.


Asunto(s)
Volumen Sanguíneo/fisiología , Oxígeno/metabolismo , Carrera/fisiología , Espectroscopía Infrarroja Corta/métodos , Adulto , Atletas , Prueba de Esfuerzo/métodos , Hemoglobinas/metabolismo , Humanos , Modelos Lineales , Masculino , Músculo Esquelético/fisiología , Reproducibilidad de los Resultados , Factores de Tiempo , Adulto Joven
12.
Int J Sports Med ; 34(2): 101-10, 2013 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22960988

RESUMEN

The purpose of this study was to quantify match play intensity distribution in young soccer players in relation to age, playing position and physical fitness. Distance covered and heart rate were measured (global positioning system) on 103, highly-trained young players (Under13 to Under 18) during 42 international club games. Maximal sprinting speed (MSS), estimated maximal aerobic speed (MAS) and maximal heart rate (HRmax) were assessed via field test measures. Distance covered and heart rate (HR) were categorized into 5 intensity zones relative to MSS and MAS and HR(max), respectively. Intensity distribution was significantly influenced by both age and playing position with younger groups, wide-midfielders and strikers covering the greatest distance above the MAS. There was a significant, negative, large-to-very large correlation (r= -0.52-0.74) between MAS and the distance run at speeds above MAS for all positions except strikers. HR responses were not different across age groups and playing positions. Distance covered below MAS were lower in the second half for all positions (P<0.05; 0.08<η(2)<0.20), while distance covered at intensities above MAS were maintained (P>0.1; 0.00<η(2)<0.03). This reduction in distance covered below MAS was not related to a player's physical capacity. Except for strikers, a superior aerobic fitness level was unlikely to affect total distance covered but was associated with a reduced individual running demand during the game.


Asunto(s)
Rendimiento Atlético/fisiología , Esfuerzo Físico/fisiología , Aptitud Física/fisiología , Fútbol/fisiología , Adolescente , Factores de Edad , Análisis de Varianza , Niño , Sistemas de Información Geográfica , Frecuencia Cardíaca , Humanos , Carrera/fisiología , Estudios de Tiempo y Movimiento
13.
J Biomech ; 153: 111602, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-37163953

RESUMEN

The aims of this study were to describe differences in the acceleration-speed (A-S) profile in-situ and to assess the week-to-week reliability of the A-S profile in-situ over a given training cycle of elite youth soccer players, in relation to the number of sessions included and analyse the effect of the inclusion or not of a specific sprint session. In this retrospective study, 18 male elite U19 football players (179.4 ± 7.1 cm; 69.0 ± 9.5 kg) participated. GPS data collected from three consecutive typical training weeks were used to calculate different combinations of A-S profile in-situ variables (theoretical maximal acceleration [A0], theoretical maximal speed [S0] and the slope of the acceleration-speed [ASslope]). The number (and content) of sessions affected mainly S0 while A0 remained similar with or without a sprint session. The reliability of the A-S profile in-situ is more related to the spread of points rather than a specific number of sessions (and thus points) and was improved when a high percentage of maximum speed (i.e. ≥ 95%) was reached. The present study showed low week-to-week variability for A0, S0 and ASslope. However, practitioners need to make sure that the values cover a sufficient range of raw data [20-95% of maximum speed] to build a clear and consistent linear regression, and in turn extrapolate meaningful A-S profile values.


Asunto(s)
Rendimiento Atlético , Carrera , Fútbol , Masculino , Humanos , Adolescente , Reproducibilidad de los Resultados , Estudios Retrospectivos , Aceleración
14.
Eur J Appl Physiol ; 112(2): 711-23, 2012 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-21656232

RESUMEN

The aim of the present study was to verify the validity of using exercise heart rate (HRex), HR recovery (HRR) and post-exercise HR variability (HRV) during and after a submaximal running test to predict changes in physical performance over an entire competitive season in highly trained young soccer players. Sixty-five complete data sets were analyzed comparing two consecutive testing sessions (3-4 months apart) collected on 46 players (age 15.1 ± 1.5 years). Physical performance tests included a 5-min run at 9 km h(-1) followed by a seated 5-min recovery period to measure HRex, HRR and HRV, a counter movement jump, acceleration and maximal sprinting speed obtained during a 40-m sprint with 10-m splits, repeated-sprint performance and an incremental running test to estimate maximal cardiorespiratory function (end test velocity V (Vam-Eval)). Possible changes in physical performance were examined for the players presenting a substantial change in HR measures over two consecutive testing sessions (greater than 3, 13 and 10% for HRex, HRR and HRV, respectively). A decrease in HRex or increase in HRV was associated with likely improvements in V (Vam-Eval); opposite changes led to unclear changes in V (Vam-Eval). Moderate relationships were also found between individual changes in HRR and sprint [r = 0.39, 90% CL (0.07;0.64)] and repeated-sprint performance [r = -0.38 (-0.05;-0.64)]. To conclude, while monitoring HRex and HRV was effective in tracking improvements in V (Vam-Eval), changes in HRR were moderately associated with changes in (repeated-)sprint performance. The present data also question the use of HRex and HRV as systematic markers of physical performance decrements in youth soccer players.


Asunto(s)
Rendimiento Atlético/fisiología , Frecuencia Cardíaca/fisiología , Monitoreo Ambulatorio/métodos , Aptitud Física/fisiología , Fútbol/fisiología , Análisis y Desempeño de Tareas , Adolescente , Humanos , Masculino
15.
Int J Sports Med ; 33(3): 230-9, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-22290323

RESUMEN

To examine the respective associations between indices of aerobic fitness, metabolic control and locomotor function and repeated sprint-performance, 61 team sport players performed: a repeated-sprint sequence (RSS), an incremental test to exhaustion to determine maximal oxygen uptake (V˙O2max) and peak incremental test speed (Inc. test speed), and 2-4 submaximal runs to determine the time constant of the primary phase of V˙O2 kinetics at exercise onset (V˙O2τon) and cessation (V˙O2τoff). The best (RSbest) sprint times and mean sprint times (RSmean) and the percent sprint decrement (%Dec) were calculated. RSmean was almost perfectly correlated with RSbest (r=0.92;90%CL(0.88;0.95)), largely correlated with Inc. test speed (r=-0.71;90%CL(- 0.79; - 0.59)) and moderately correlated with V˙O2max (r= - 0.58;90%CL(- 0.70; - 0.43)); the correlations with V˙O2τon or V˙O2τoff were unclear. For%Dec, the correlations with Inc. test speed, V˙O2max and V˙O2τon were moderate (r=- 0.41;90%CL(- 0.56; - 0.23)), small (r=- 0.26;90%CL(- 0.43; - 0.06)) and small (r=0.28;90%CL(0.09;0.46)), respectively. Stepwise multiple regression analyses showed that the only significant predictors of RSmean were RSbest and Inc. test speed (r 2=0.88). Inc. test speed and RSbest were also the only significant predictors of %Dec (r 2=0.26). Present results obtained in a large sample of team sport players highlight that locomotor factors (i. e., RSbest and Inc. test speed) show much larger associations with repeated-sprint performance than V˙O2max and V˙O2 kinetics.


Asunto(s)
Umbral Anaerobio/fisiología , Rendimiento Atlético/fisiología , Consumo de Oxígeno/fisiología , Carrera/fisiología , Adolescente , Adulto , Prueba de Esfuerzo , Humanos , Masculino , Actividad Motora/fisiología , Aptitud Física/fisiología , Análisis de Regresión
16.
S Afr J Sports Med ; 34(1): v34i1a13102, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36815932

RESUMEN

Background: Wearable resistance (WR) training is a modality that allows athletes to perform loaded sport-specific movements to develop force and power outputs. The acute responses by which WR works is still relatively unknown, and the effects of WR load and location of the load has not yet been examined. Objectives: To investigate the acute neuromuscular and stride characteristic responses to different wearable resistance (WR) loads and placements on the calf muscles during high-speed running. Methods: Ten well-trained subjects completed a workout of ten sets of three 10s runs at 18km.h-1 (20s of rest between runs and one min between sets). Five conditions were tested: (1) unloaded control, (2) bilateral 0.75 vs. 1.5% body mass (BM) loading on the distal posterior calf, (3) bilateral proximal vs. distal loading of 1.5% BM positioned posteriorly, (4) bilateral anterior vs. posterior loading of 1.5% BM positioned distally, (5) unilateral loading of 1.5% BM on the distal posterior calf. Data were collected using Electromyography (EMG) and back-mounted GPS-embedded accelerometers. Magnitude of differences of within athlete and between muscle comparisons were calculated using effect sizes (ES) ± 90% confidence limits (CL). Results: No substantial differences in accelerometry data were observed between any of the loaded conditions and the control. EMG activity was lower for proximal loading compared to the control for the gluteus maximus (ES±90%CL; -0.72±0.41), vastus lateralis (-0.89±0.47) and vastus medialis (VM) (-0.97±0.46). Anterior loading induced substantially lower EMG activity for the semitendinosus (-0.70±0.48) and VM (-0.64±0.39) muscles compared with the control. EMG activity of the VM (-0.73±0.46) muscle was also substantially lower for posterior loading compared to the control. Unilateral loading induced no substantial differences in EMG activity between the loaded and unloaded legs. Conclusion: This preliminary study has provided a rationale for the performance of further investigations into the effects of WR lower limb loading on stride characteristics and EMG activity from a chronic standpoint using a larger population.

17.
Scand J Med Sci Sports ; 21(6): e477-85, 2011 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-22092960

RESUMEN

The aim of the present study was to examine the associations between adaptive responses to an in-season soccer training camp in the heat and changes in submaximal exercising heart rate (HRex, 5-min run at 9 km/h), postexercise HR recovery (HRR) and HR variability (HRV). Fifteen well-trained but non-heat-acclimatized male adult players performed a training week in Qatar (34.6 ± 1.9°C wet bulb globe temperature). HRex, HRR, HRV (i.e. the standard deviation of instantaneous beat-to-beat R-R interval variability measured from Poincaré plots SD1, a vagal-related index), creatine kinase (CK) activity, plasma volume (PV) changes, and post-5-min run rate of perceived exertion (RPE) were collected at six occasions in temperate environmental conditions (22°C). Players also performed the yo-yo intermittent recovery test level 1 (Yo-Yo IR1) in the same environmental conditions (22°C), both at the beginning and at the end of the training week. Throughout the intervention, HRex and HRV showed decreasing (P < 0.001) and increasing (P < 0.001) trends, respectively, while HRR remained unaffected (P = 0.84). Changes in HRex [-0.52, 90% confidence limits (-0.64; -0.38), P < 0.001] and SD1 [0.35 (0.19; 0.49), P < 0.001] were correlated with those in PV. There was no change in RPE (P = 0.92), while CK varied according to training contents (P < 0.001), without association with HR-derived measures. Yo-Yo IR1 performance increased by 7 ± 9% (P = 0.009), which was correlated with changes in HRex [-0.64 (-0.84; -0.28), P = 0.01]. In conclusion, we found that an in-season soccer training camp in the heat can significantly improve PV and soccer-specific physical performance; both of which are associated with changes in HRex during a 5-min submaximal run.


Asunto(s)
Adaptación Fisiológica , Rendimiento Atlético/fisiología , Frecuencia Cardíaca/fisiología , Calor , Fútbol , Aclimatación/fisiología , Adulto , Prueba de Esfuerzo/métodos , Humanos , Masculino , Qatar , Adulto Joven
18.
Int J Sports Med ; 32(8): 598-605, 2011 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-21574126

RESUMEN

In this study, we compared the reliability of short-term resting heart rate (HR) variability (HRV) and postexercise parasympathetic reactivation (i.e., HR recovery (HRR) and HRV) indices following either submaximal or supramaximal exercise. On 4 different occasions, beat-to-beat HR was recorded in 15 healthy males (21.5 ± 1.4 yr) during 5 min of seated rest, followed by submaximal (Sub) and supramaximal (Supra) exercise bouts; both exercise bouts were followed by 5 min of seated recovery. Reliability of all HR-derived indices was assessed by the typical error of measurement expressed as a coefficient of variation (CV,%). CV for HRV indices ranged from 4 to 17%, 7 to 27% and 41 to 82% for time domain, spectral and ratio indices, respectively. The CV for HRR ranged from 15 to 32%. Spectral CVs for HRV were lower at rest compared with Supra (e.g., natural logarithm of the high frequency range (LnHF); 12.6 vs. 26.2%; P=0.02). HRR reliability was not different between Sub and Supra (25 vs. 14%; P=0.10). The present study found discrepancy in the CVs of vagal-related heart rate indices; a finding that should be appreciated when assessing changes in these variables. Further, Supra exercise was shown to worsen the reliability of HRV-spectral indices.


Asunto(s)
Prueba de Esfuerzo , Ejercicio Físico/fisiología , Frecuencia Cardíaca/fisiología , Humanos , Masculino , Reproducibilidad de los Resultados , Nervio Vago/fisiología , Adulto Joven
19.
Int J Sports Med ; 31(11): 818-25, 2010 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-20703978

RESUMEN

The activity profiles of highly trained young soccer players were examined in relation to age, playing position and physical capacity. Time-motion analyses (global positioning system) were performed on 77 (U13-U18; fullbacks [FB], centre-backs [CB], midfielders [MD], wide midfielders [W], second strikers [2 (nd)S] and strikers [S]) during 42 international club games. Total distance covered (TD) and very high-intensity activities (VHIA; >16.1 km·h (-1)) were computed during 186 entire player-matches. Physical capacity was assessed via field test measures (e. g., peak running speed during an incremental field test, VVam-eval). Match running performance showed an increasing trend with age ( P<0.001, partial eta-squared (η (2)): 0.20-0.45). When adjusted for age and individual playing time, match running performance was position-dependent ( P<0.001, η (2): 0.13-0.40). MD covered the greater TD; CB the lowest ( P<0.05). Distance for VHIA was lower for CB compared with all other positions ( P<0.05); W and S displayed the highest VHIA ( P<0.05). Relationships between match running performance and physical capacities were position-dependent, with poor or non-significant correlations within FB, CB, MD and W (e. g., VHIA vs. VVam-eval: R=0.06 in FB) but large associations within 2 (nd)S and S positions (e. g., VHIA vs. VVam-eval: R=0.70 in 2 (nd)S). In highly trained young soccer players, the importance of fitness level as a determinant of match running performance should be regarded as a function of playing position.


Asunto(s)
Rendimiento Atlético/fisiología , Carrera/fisiología , Fútbol/fisiología , Adolescente , Factores de Edad , Humanos , Aptitud Física/fisiología , Estudios de Tiempo y Movimiento
20.
Int J Sports Med ; 31(10): 709-16, 2010 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-20617485

RESUMEN

This study examined the occurrence and nature of repeated-sprint sequences (RSS) in highly-trained young soccer players, as a function of age, playing position and playing time. Time-motion analyses using a global positioning system (GPS) were performed on 99 highly-trained young soccer (U13, U14, U15, U16, U17 and U18) players during 42 international games. Sprint activities were defined as at least a 1-s run at intensities higher than 61% of the individual peak running velocity; RSS, as a minimum of 2 consecutive sprints interspersed with a maximum of 60 s. During the first half of games the younger teams had a greater number of RSS than the older teams (P<0.001): U13>U14>U16>U15>U18>U17. The younger players also performed more (e. g., U14 vs. U17: 2.8±0.3 vs. 2.6±0.3, P<0.05) and longer (e. g., U14 vs. U17: 2.8±0.5 vs. 2.6±0.5 s, P<0.05) sprints per sequence than the older players. RSS occurrence was also affected by playing position and decreased throughout the game in most age-groups (P<0.001). Both the occurrence and the nature of RSS are affected by age, position and playing time. Present results also question the importance of repeated-sprint ability as a crucial physical component of soccer performance in developing players.


Asunto(s)
Rendimiento Atlético/fisiología , Carrera/fisiología , Fútbol/fisiología , Adolescente , Factores de Edad , Atletas , Niño , Sistemas de Información Geográfica , Humanos , Factores de Tiempo , Estudios de Tiempo y Movimiento
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