Priscila Torrado - Academia.edu (original) (raw)

Papers by Priscila Torrado

PLOS ONE

Maneuvering a motorcycle in racing conditions or for prolonged time is sufficiently demanding tha... more Maneuvering a motorcycle in racing conditions or for prolonged time is sufficiently demanding that on many occasions forearm muscles reach a state of functional failure when riders cannot properly brake or operate the throttle. This study intends to discriminate which ones of the several dynamometric parameters used in the literature to characterize the Force-time (F-t) curve during voluntary contractions are more sensitive to neuromuscular fatigue in simulated motorcycle-riding conditions. Thirty-three adults performed an intermittent fatiguing protocol (IFP) that simulated the brake-pulling and throttle-twisting actions, by using a hydraulic system equipped with a pressure sensor. Sixty pressure-time (P-t) curve parameters, including the rate of pressure development (RPD) and area under the curve were measured to characterize the time course of the braking maximal voluntary contraction (MVC). Two types of variables were used to analyze the P-t curve: 1) Times interval (from 0 to 3...

Archivos de Medicina del Deporte

Highly repetitive submaximal intermittent contractions of the forearm muscles during periods of 3... more Highly repetitive submaximal intermittent contractions of the forearm muscles during periods of 30-50 min partially explain why motorcycle races are so demanding for the neuromuscular system. This study investigated the contribution of central and peripheral mechanisms of fatigue on the exerted and contralateral extensor digitorum communis following an intermittent fatigue protocol (IFP) designed for motorcycle riders. 12 riders performed an IFP, which simulates the braking and throttle handle gesture. We examined the time course of recovery of maximal voluntary contraction (MVC), M-wave, motor evoked potential (MEP) to transcranial magnetic stimuli in relaxed and facilitated condition, and the cortical silent period (CSP) at time windows of 1, 3, 5, 10 and 20 min after the IFP. Whereas MVC, M-wave and MEP decreased, CSP lengthened significantly in the fatigued limb after completion of the IFP. Nevertheless, no differences were observed in the contralateral limb. All neurophysiological parameters reverted to baseline values in less than 20 min, while MVC remained lower in the exercised limb. No cross-over effects were observed in the contralateral non-exercised limb. Our results suggest that local factors are those mainly responsible for the incomplete MVC recovery after an intermittent muscle contraction protocol.

Journal of Electromyography and Kinesiology, 2013

This case study examined the nutritional behavior and energy balance in an official finisher of a... more This case study examined the nutritional behavior and energy balance in an official finisher of a 24-hour ultracycling race. The food and beverages consumed by the cyclist were continuously weighed and recorded to estimate intake of energy, macronutrients, sodium, and caffeine. In addition, during the race, heart rate was continuously monitored. Energy
expenditure was assessed using a heart rate–oxygen uptake regression
equation obtained previously from a laboratory test. The athlete (39 years,
175.6 cm, 84.2 kg, maximum oxygen uptake, 64 mL/kg/min) cycled during 22 h 22 min, in which he completed 557.3 km with 8760 m of altitude at an average speed of 25.1 km/h. The average heart rate was 131 beats/min. Carbohydrates were the main macronutrient intake (1102 g, 13.1 g/kg); however, intake was below current recommendations.
The consumption of protein and fat was 86 g and 91 g, respectively. He ingested 20.7 L (862 mL/h) of fluids, with sport drinks the main fluid used for hydration. Sodium concentration in relation to total fluid intake was 34.0 mmol/L. Caffeine consumption over the race was 231 mg (2.7 mg/kg). During the race, he expended 15,533 kcal. Total energy intake was 5571 kcal, with 4058 (73%) and 1513 (27%) kcal derived from solids and fluids, respectively. The energy balance resulted in an
energy deficit of 9915 kcal.

Journal of sports sciences

The objective of this study was to confirm whether gymnastics practice from a young age can induc... more The objective of this study was to confirm whether gymnastics practice from a young age can induce greater vertical jump reliability. Fifty young female gymnasts (8.84 ± 0.62 years) and 42 females in the control group (8.58 ± 0.92 years) performed the following jump tests on a contact mat: squat jump, countermovement jump, countermovement jump with arm swing and drop jump from heights of 40 and 60 cm. The two testing sessions had three trials each and were separated by one week. A 2 (groups) × 2 (sessions) × 3 (trials) repeated measures analysis of variance (ANOVA) and a test-retest correlation analysis were used to study the reliability. There was no systematic source of error in either group for non-plyometric jumps such as squat jump, countermovement jump, and countermovement jump with arm swing. A significant group per trial interaction revealed a learning effect in gymnasts' drop jumps from 40 cm height. Additionally, the test-retest correlation analysis and the higher minimum detectable error suggest that the quick drop jump technique was not fully consolidated in either group. At an introductory level of gymnastics and between the ages of 8–10 years, the condition of being a gymnast did not lead to conclusively higher reliability, aside from better overall vertical jump performance.

International journal of sports medicine

Highly repetitive submaximal intermittent contractions of the forearm muscles during periods of 3... more Highly repetitive submaximal intermittent contractions of the forearm muscles during periods of 30–50 min partially explain why motorcycle races are so demanding for the neuromuscular system. This study investigated the contribution of central and peripheral mechanisms of fatigue on the exerted and contralateral extensor digitorum communis following an intermittent fatigue protocol (IFP) designed for motorcycle riders. 12 riders performed an IFP, which simulates the braking and throttle handle gesture. We examined the time course of recovery of maximal voluntary contraction (MVC), M-wave, motor evoked potential (MEP) to transcranial magnetic stimuli in relaxed and facilitated condition, and the cortical silent period (CSP) at time windows of 1, 3, 5, 10 and 20 min after the IFP. Whereas MVC, M-wave and MEP decreased, CSP lengthened significantly in the fatigued limb after completion of the IFP. Nevertheless, no differences were observed in the contralateral limb. All neurophysiological parameters reverted to baseline values in less than 20 min, while MVC remained lower in the exercised limb. No cross-over effects were observed in the contralateral non-exercised limb. Our results suggest that local factors are those mainly responsible for the incomplete MVC recovery after an intermittent muscle contraction protocol.

Background: Information about behavior of energy intake in ultra-endurance cyclists during a 24-h... more Background: Information about behavior of energy intake in ultra-endurance cyclists during a 24-hour team relay race is scarce. The nutritional strategy during such an event is an important factor which athletes should plan carefully before the race. The purpose of this study was to examine and compare the nutritional intake of ultraendurance
cyclists during a 24-hour team relay race with the current nutritional guidelines for endurance events.
Additionally, we analyzed the relationship among the nutritional and performance variables.
Methods: Using a observational design, nutritional intake of eight males (mean ± SD: 36.7 ± 4.7 years; 71.6 ± 4.9
kg; 174.6 ± 7.3 cm; BMI 23.5 ± 0.5 kg/m2) participating in a 24-hour team relay cycling race was assessed. All food and fluid intake by athletes were weighed and recorded. Additionally, distance and speed performed by each rider were also recorded. Furthermore, before to the race, all subjects carried out an incremental exercise test to determine two heart rate-VO2 regression equations which were used to estimate the energy expenditure.
Results: The mean ingestion of macronutrients during the event was 943 ± 245 g (13.1 ± 4.0 g/kg) of carbohydrates, 174 ± 146 g (2.4 ± 1.9 g/kg) of proteins and 107 ± 56 g (1.5 ± 0.7 g/kg) of lipids, respectively. This amount of nutrients reported an average nutrient intake of 22.8 ± 8.9 MJ which were significantly lower compared with energy expenditure 42.9 ± 6.8 MJ (P = 0.012). Average fluid consumption corresponded to 10497 ± 2654 mL.
Mean caffeine ingestion was 142 ± 76 mg. Additionally, there was no relationship between the main nutritional variables (i.e. energy intake, carbohydrates, proteins, fluids and caffeine ingestion) and the main performance variables (i.e. distance and speed).
Conclusions: A 24-hour hours cycling competition in a team relay format elicited high energy demands which were not compensated by energy intake of the athletes despite that dietary consumption of macronutrients did not differ to the nutritional guidelines for longer events.

This study was to describe and compare the physiological demands of ultra-endurance cyclists duri... more This study was to describe and compare the physiological demands of ultra-endurance cyclists during a 24 h cycling relay race. Eleven male athletes (means ± SD: 34.8 ± 5.6 years; 71.6 ± 4.9 kg; 174.6 ± 7.3 cm; BMI 23.5 ± 0.5 kg/m2; VO2max: 66.0 ± 6.4 ml/kg/min) participated in the study; eight in teams with a format of four riders (4C) and three in teams with six riders (6C). To investigate exercise intensity, heart rate (HR) was recorded while cycling using portable telemetric monitors. Three different exercise intensities were defined according to the reference HR values obtained during a pre race
laboratory incremental VO2max test: Zone I (< anaerobic threshold [AT]), Zone II (between AT and the respiratory compensation point [RCP]), Zone III (> RCP). Total volume and intensity were integrated as a single variable (training impulse: TRIMP). The score for TRIMP in each zone was computed by
multiplying the accumulated duration in this zone by a multiplier for this particular zone of exercise intensity. The average intensity did not differ between cyclists in 4C (means ± SD; 4C: 87 ± 3 HRmax) and 6C (87 ± 1% of HRmax), despite the higher volume performed by 4C (means ± SD; 4C: 361 ± 65; 6C:
242 ± 25 per min; P = 0.012). These differences in total exercise volume significantly affected the values TRIMP accumulated (means ± SD; 4C: 801 ± 98, confidence interval [CI] 95%: 719 – 884; 6C: 513 ± 25, CI 95%: 451 – 575; P = 0.012). The ultra-endurance threshold of 4C and 6C athletes lies at about 87%
of HRmax for both. Although the intensity profile was similar, the TRIMP values differed significantly as a consequence of the higher volume performed by the 4C cyclists.

Journal of Electromyography and Kinesiology, 2013

Fatigue in forearm muscles may be critical for motorcycle riders in relation to performance and f... more Fatigue in forearm muscles may be critical for motorcycle riders in relation to performance and forearm disorders. Force-time course parameters were examined to better characterize the reduction in the maximal force generating capacity (MVC) during an intermittent fatigue protocol (IFP) specifically designed for motorcycle riders. Also, a mathematical force fatigue model is proposed. Forty motorcyclists (aged 27.6 ± 6.8 years) performed an IFP that simulated the braking gesture and posture of a rider. Fatigue was confirmed by a 40% decrement of the normalized MVC in comparison to basal value. Contraction time increased in comparison to basal condition (P ≤ 0.034). Relaxation kinetics presented two phases: (1) a pre-fatigue phase where half relaxation time (HRTraw) and normalized (HRTnor) decreased (P ≤ 0.013) while relaxation rate (RRraw) remained unchanged; and (2) a fatiguing phase where HRTraw, HRTnor increased and RRraw decreased (P ≤ 0.047). Normalized RRraw (RRnor) declined progressively (P ≤ 0.016). The proposed nonlinear force fatigue model confirmed a satisfactory adjustment (R2 = 0.977 ± 0.018). This mathematical expression derived three patterns of force fatigue: three-phase, exponential and linear, representing 70%, 13% and 17% of the participants, respectively. Overall, these results provided further support to force fatigue theoretical and applied proposals.

Scandinavian Journal of Medicine & Science in Sports, 2014

Fatigue in forearm muscles may be critical for motorcycle riders in relation to performance and f... more Fatigue in forearm muscles may be critical for motorcycle riders in relation to performance and forearm disorders. Force-time course parameters were examined to better characterize the reduction in the maximal force generating capacity (MVC) during an intermittent fatigue protocol (IFP) specifically designed for motorcycle riders. Also, a mathematical force fatigue model is proposed. Forty motorcyclists (aged 27.6 ± 6.8 years) performed an IFP that simulated the braking gesture and posture of a rider. Fatigue was confirmed by a 40% decrement of the normalized MVC in comparison to basal value. Contraction time increased in comparison to basal condition (P ≤ 0.034). Relaxation kinetics presented two phases: (1) a pre-fatigue phase where half relaxation time (HRTraw) and normalized (HRTnor) decreased (P ≤ 0.013) while relaxation rate (RRraw) remained unchanged; and (2) a fatiguing phase where HRTraw, HRTnor increased and RRraw decreased (P ≤ 0.047). Normalized RRraw (RRnor) declined progressively (P ≤ 0.016). The proposed nonlinear force fatigue model confirmed a satisfactory adjustment (R2 = 0.977 ± 0.018). This mathematical expression derived three patterns of force fatigue: three-phase, exponential and linear, representing 70%, 13% and 17% of the participants, respectively. Overall, these results provided further support to force fatigue theoretical and applied proposals.

Introducción y objetivos La fiabilidad de los tests de salto vertical es inferior en niños que e... more Introducción y objetivos

La fiabilidad de los tests de salto vertical es inferior en niños que en adultos. El objetivo del presente estudio es determinar si niñas prepúberes que practican un entrenamiento específico de gimnasia artística son más fiables en distintas pruebas de salto vertical que un grupo control de niñas de la misma edad.

Método

Participaron en el estudio 36 prepúberes (19 gimnastas y 17 control), con edades comprendidas entre 7 y 12 años. Para estudiar la fiabilidad de la capacidad de salto «entre intentos» y «entre sesiones» se utilizaron las siguientes pruebas de salto: squat jump (SJ), countermovement jump (CMJ), countermovement jump with arm swing (CMJA) y drop jump (DJ). Se administraron las pruebas en dos ocasiones, realizándose tres intentos en cada sesión.

Resultados

Se observaron altos coeficientes de correlación intraclase (ICC≥0,75) entre intentos y entre sesiones para todas las pruebas. Se cuestiona la fiabilidad del CMJ en gimnastas al encontrarse diferencias significativas en la comparación entre intentos y entre sesiones (p≤0,05).

Conclusiones

Se concluye que desde temprana edad la capacidad de salto es reproducible y fiable, y que la práctica de gimnasia artística, en niveles de iniciación, no mejora la fiabilidad de la mayoría de tests de salto vertical.

PLOS ONE

Maneuvering a motorcycle in racing conditions or for prolonged time is sufficiently demanding tha... more Maneuvering a motorcycle in racing conditions or for prolonged time is sufficiently demanding that on many occasions forearm muscles reach a state of functional failure when riders cannot properly brake or operate the throttle. This study intends to discriminate which ones of the several dynamometric parameters used in the literature to characterize the Force-time (F-t) curve during voluntary contractions are more sensitive to neuromuscular fatigue in simulated motorcycle-riding conditions. Thirty-three adults performed an intermittent fatiguing protocol (IFP) that simulated the brake-pulling and throttle-twisting actions, by using a hydraulic system equipped with a pressure sensor. Sixty pressure-time (P-t) curve parameters, including the rate of pressure development (RPD) and area under the curve were measured to characterize the time course of the braking maximal voluntary contraction (MVC). Two types of variables were used to analyze the P-t curve: 1) Times interval (from 0 to 3...

Archivos de Medicina del Deporte

Highly repetitive submaximal intermittent contractions of the forearm muscles during periods of 3... more Highly repetitive submaximal intermittent contractions of the forearm muscles during periods of 30-50 min partially explain why motorcycle races are so demanding for the neuromuscular system. This study investigated the contribution of central and peripheral mechanisms of fatigue on the exerted and contralateral extensor digitorum communis following an intermittent fatigue protocol (IFP) designed for motorcycle riders. 12 riders performed an IFP, which simulates the braking and throttle handle gesture. We examined the time course of recovery of maximal voluntary contraction (MVC), M-wave, motor evoked potential (MEP) to transcranial magnetic stimuli in relaxed and facilitated condition, and the cortical silent period (CSP) at time windows of 1, 3, 5, 10 and 20 min after the IFP. Whereas MVC, M-wave and MEP decreased, CSP lengthened significantly in the fatigued limb after completion of the IFP. Nevertheless, no differences were observed in the contralateral limb. All neurophysiological parameters reverted to baseline values in less than 20 min, while MVC remained lower in the exercised limb. No cross-over effects were observed in the contralateral non-exercised limb. Our results suggest that local factors are those mainly responsible for the incomplete MVC recovery after an intermittent muscle contraction protocol.

Journal of Electromyography and Kinesiology, 2013

This case study examined the nutritional behavior and energy balance in an official finisher of a... more This case study examined the nutritional behavior and energy balance in an official finisher of a 24-hour ultracycling race. The food and beverages consumed by the cyclist were continuously weighed and recorded to estimate intake of energy, macronutrients, sodium, and caffeine. In addition, during the race, heart rate was continuously monitored. Energy
expenditure was assessed using a heart rate–oxygen uptake regression
equation obtained previously from a laboratory test. The athlete (39 years,
175.6 cm, 84.2 kg, maximum oxygen uptake, 64 mL/kg/min) cycled during 22 h 22 min, in which he completed 557.3 km with 8760 m of altitude at an average speed of 25.1 km/h. The average heart rate was 131 beats/min. Carbohydrates were the main macronutrient intake (1102 g, 13.1 g/kg); however, intake was below current recommendations.
The consumption of protein and fat was 86 g and 91 g, respectively. He ingested 20.7 L (862 mL/h) of fluids, with sport drinks the main fluid used for hydration. Sodium concentration in relation to total fluid intake was 34.0 mmol/L. Caffeine consumption over the race was 231 mg (2.7 mg/kg). During the race, he expended 15,533 kcal. Total energy intake was 5571 kcal, with 4058 (73%) and 1513 (27%) kcal derived from solids and fluids, respectively. The energy balance resulted in an
energy deficit of 9915 kcal.

Journal of sports sciences

The objective of this study was to confirm whether gymnastics practice from a young age can induc... more The objective of this study was to confirm whether gymnastics practice from a young age can induce greater vertical jump reliability. Fifty young female gymnasts (8.84 ± 0.62 years) and 42 females in the control group (8.58 ± 0.92 years) performed the following jump tests on a contact mat: squat jump, countermovement jump, countermovement jump with arm swing and drop jump from heights of 40 and 60 cm. The two testing sessions had three trials each and were separated by one week. A 2 (groups) × 2 (sessions) × 3 (trials) repeated measures analysis of variance (ANOVA) and a test-retest correlation analysis were used to study the reliability. There was no systematic source of error in either group for non-plyometric jumps such as squat jump, countermovement jump, and countermovement jump with arm swing. A significant group per trial interaction revealed a learning effect in gymnasts' drop jumps from 40 cm height. Additionally, the test-retest correlation analysis and the higher minimum detectable error suggest that the quick drop jump technique was not fully consolidated in either group. At an introductory level of gymnastics and between the ages of 8–10 years, the condition of being a gymnast did not lead to conclusively higher reliability, aside from better overall vertical jump performance.

International journal of sports medicine

Highly repetitive submaximal intermittent contractions of the forearm muscles during periods of 3... more Highly repetitive submaximal intermittent contractions of the forearm muscles during periods of 30–50 min partially explain why motorcycle races are so demanding for the neuromuscular system. This study investigated the contribution of central and peripheral mechanisms of fatigue on the exerted and contralateral extensor digitorum communis following an intermittent fatigue protocol (IFP) designed for motorcycle riders. 12 riders performed an IFP, which simulates the braking and throttle handle gesture. We examined the time course of recovery of maximal voluntary contraction (MVC), M-wave, motor evoked potential (MEP) to transcranial magnetic stimuli in relaxed and facilitated condition, and the cortical silent period (CSP) at time windows of 1, 3, 5, 10 and 20 min after the IFP. Whereas MVC, M-wave and MEP decreased, CSP lengthened significantly in the fatigued limb after completion of the IFP. Nevertheless, no differences were observed in the contralateral limb. All neurophysiological parameters reverted to baseline values in less than 20 min, while MVC remained lower in the exercised limb. No cross-over effects were observed in the contralateral non-exercised limb. Our results suggest that local factors are those mainly responsible for the incomplete MVC recovery after an intermittent muscle contraction protocol.

Background: Information about behavior of energy intake in ultra-endurance cyclists during a 24-h... more Background: Information about behavior of energy intake in ultra-endurance cyclists during a 24-hour team relay race is scarce. The nutritional strategy during such an event is an important factor which athletes should plan carefully before the race. The purpose of this study was to examine and compare the nutritional intake of ultraendurance
cyclists during a 24-hour team relay race with the current nutritional guidelines for endurance events.
Additionally, we analyzed the relationship among the nutritional and performance variables.
Methods: Using a observational design, nutritional intake of eight males (mean ± SD: 36.7 ± 4.7 years; 71.6 ± 4.9
kg; 174.6 ± 7.3 cm; BMI 23.5 ± 0.5 kg/m2) participating in a 24-hour team relay cycling race was assessed. All food and fluid intake by athletes were weighed and recorded. Additionally, distance and speed performed by each rider were also recorded. Furthermore, before to the race, all subjects carried out an incremental exercise test to determine two heart rate-VO2 regression equations which were used to estimate the energy expenditure.
Results: The mean ingestion of macronutrients during the event was 943 ± 245 g (13.1 ± 4.0 g/kg) of carbohydrates, 174 ± 146 g (2.4 ± 1.9 g/kg) of proteins and 107 ± 56 g (1.5 ± 0.7 g/kg) of lipids, respectively. This amount of nutrients reported an average nutrient intake of 22.8 ± 8.9 MJ which were significantly lower compared with energy expenditure 42.9 ± 6.8 MJ (P = 0.012). Average fluid consumption corresponded to 10497 ± 2654 mL.
Mean caffeine ingestion was 142 ± 76 mg. Additionally, there was no relationship between the main nutritional variables (i.e. energy intake, carbohydrates, proteins, fluids and caffeine ingestion) and the main performance variables (i.e. distance and speed).
Conclusions: A 24-hour hours cycling competition in a team relay format elicited high energy demands which were not compensated by energy intake of the athletes despite that dietary consumption of macronutrients did not differ to the nutritional guidelines for longer events.

This study was to describe and compare the physiological demands of ultra-endurance cyclists duri... more This study was to describe and compare the physiological demands of ultra-endurance cyclists during a 24 h cycling relay race. Eleven male athletes (means ± SD: 34.8 ± 5.6 years; 71.6 ± 4.9 kg; 174.6 ± 7.3 cm; BMI 23.5 ± 0.5 kg/m2; VO2max: 66.0 ± 6.4 ml/kg/min) participated in the study; eight in teams with a format of four riders (4C) and three in teams with six riders (6C). To investigate exercise intensity, heart rate (HR) was recorded while cycling using portable telemetric monitors. Three different exercise intensities were defined according to the reference HR values obtained during a pre race
laboratory incremental VO2max test: Zone I (< anaerobic threshold [AT]), Zone II (between AT and the respiratory compensation point [RCP]), Zone III (> RCP). Total volume and intensity were integrated as a single variable (training impulse: TRIMP). The score for TRIMP in each zone was computed by
multiplying the accumulated duration in this zone by a multiplier for this particular zone of exercise intensity. The average intensity did not differ between cyclists in 4C (means ± SD; 4C: 87 ± 3 HRmax) and 6C (87 ± 1% of HRmax), despite the higher volume performed by 4C (means ± SD; 4C: 361 ± 65; 6C:
242 ± 25 per min; P = 0.012). These differences in total exercise volume significantly affected the values TRIMP accumulated (means ± SD; 4C: 801 ± 98, confidence interval [CI] 95%: 719 – 884; 6C: 513 ± 25, CI 95%: 451 – 575; P = 0.012). The ultra-endurance threshold of 4C and 6C athletes lies at about 87%
of HRmax for both. Although the intensity profile was similar, the TRIMP values differed significantly as a consequence of the higher volume performed by the 4C cyclists.

Journal of Electromyography and Kinesiology, 2013

Fatigue in forearm muscles may be critical for motorcycle riders in relation to performance and f... more Fatigue in forearm muscles may be critical for motorcycle riders in relation to performance and forearm disorders. Force-time course parameters were examined to better characterize the reduction in the maximal force generating capacity (MVC) during an intermittent fatigue protocol (IFP) specifically designed for motorcycle riders. Also, a mathematical force fatigue model is proposed. Forty motorcyclists (aged 27.6 ± 6.8 years) performed an IFP that simulated the braking gesture and posture of a rider. Fatigue was confirmed by a 40% decrement of the normalized MVC in comparison to basal value. Contraction time increased in comparison to basal condition (P ≤ 0.034). Relaxation kinetics presented two phases: (1) a pre-fatigue phase where half relaxation time (HRTraw) and normalized (HRTnor) decreased (P ≤ 0.013) while relaxation rate (RRraw) remained unchanged; and (2) a fatiguing phase where HRTraw, HRTnor increased and RRraw decreased (P ≤ 0.047). Normalized RRraw (RRnor) declined progressively (P ≤ 0.016). The proposed nonlinear force fatigue model confirmed a satisfactory adjustment (R2 = 0.977 ± 0.018). This mathematical expression derived three patterns of force fatigue: three-phase, exponential and linear, representing 70%, 13% and 17% of the participants, respectively. Overall, these results provided further support to force fatigue theoretical and applied proposals.

Scandinavian Journal of Medicine & Science in Sports, 2014

Fatigue in forearm muscles may be critical for motorcycle riders in relation to performance and f... more Fatigue in forearm muscles may be critical for motorcycle riders in relation to performance and forearm disorders. Force-time course parameters were examined to better characterize the reduction in the maximal force generating capacity (MVC) during an intermittent fatigue protocol (IFP) specifically designed for motorcycle riders. Also, a mathematical force fatigue model is proposed. Forty motorcyclists (aged 27.6 ± 6.8 years) performed an IFP that simulated the braking gesture and posture of a rider. Fatigue was confirmed by a 40% decrement of the normalized MVC in comparison to basal value. Contraction time increased in comparison to basal condition (P ≤ 0.034). Relaxation kinetics presented two phases: (1) a pre-fatigue phase where half relaxation time (HRTraw) and normalized (HRTnor) decreased (P ≤ 0.013) while relaxation rate (RRraw) remained unchanged; and (2) a fatiguing phase where HRTraw, HRTnor increased and RRraw decreased (P ≤ 0.047). Normalized RRraw (RRnor) declined progressively (P ≤ 0.016). The proposed nonlinear force fatigue model confirmed a satisfactory adjustment (R2 = 0.977 ± 0.018). This mathematical expression derived three patterns of force fatigue: three-phase, exponential and linear, representing 70%, 13% and 17% of the participants, respectively. Overall, these results provided further support to force fatigue theoretical and applied proposals.

Introducción y objetivos La fiabilidad de los tests de salto vertical es inferior en niños que e... more Introducción y objetivos

La fiabilidad de los tests de salto vertical es inferior en niños que en adultos. El objetivo del presente estudio es determinar si niñas prepúberes que practican un entrenamiento específico de gimnasia artística son más fiables en distintas pruebas de salto vertical que un grupo control de niñas de la misma edad.

Método

Participaron en el estudio 36 prepúberes (19 gimnastas y 17 control), con edades comprendidas entre 7 y 12 años. Para estudiar la fiabilidad de la capacidad de salto «entre intentos» y «entre sesiones» se utilizaron las siguientes pruebas de salto: squat jump (SJ), countermovement jump (CMJ), countermovement jump with arm swing (CMJA) y drop jump (DJ). Se administraron las pruebas en dos ocasiones, realizándose tres intentos en cada sesión.

Resultados

Se observaron altos coeficientes de correlación intraclase (ICC≥0,75) entre intentos y entre sesiones para todas las pruebas. Se cuestiona la fiabilidad del CMJ en gimnastas al encontrarse diferencias significativas en la comparación entre intentos y entre sesiones (p≤0,05).

Conclusiones

Se concluye que desde temprana edad la capacidad de salto es reproducible y fiable, y que la práctica de gimnasia artística, en niveles de iniciación, no mejora la fiabilidad de la mayoría de tests de salto vertical.