The Slow Component of Oxygen Uptake and Efficiency in Resistance Exercises: A Comparison With Endurance Exercises

IntroductionThere is a lack of information regarding the slow component of oxygen uptake (VO2sc) and efficiency/economy in resistance exercises despite the crucial role played in endurance performance.Purposethis study aimed to compare the VO2sc, efficiency/economy, metabolic, cardiorespiratory responses, rating of perceived effort and mechanical fatigue between cycling and half-squat (HS) exercises during a constant-load test at lactate threshold (LT1) intensity.MethodsTwenty-one healthy men were randomly assigned in a crossover design to perform cycle-ergometer or HS tests. The order of the two cycle ergometer tests was an incremental test for determining load-intensity in watts (W) at LT1, followed by a constant-load test at the LT1 intensity. For the three HS tests, the order was a 1RM test to determine the load (kg) corresponding to the 1RM percentages to be used during the second test, incremental HS exercise to establish the load (kg) at the LT1 intensity, and finally, a constant-load HS test at the LT1 intensity. A rest period of 48 h between each test was established. During the HS and cycle-ergometer constant-load tests, cardiorespiratory and metabolic responses were recorded. Lower limbs fatigue was determined by a jump test before and after the constant-load tests.ResultsA significant exercise mode × time interaction effect was detected in VO2, heart rate, energy expenditure (EE), gross efficiency (GE), and economy (p < 0.05). A significant and sustained VO2 raise was confirmed in HS exercise (p < 0.05) and a steady-state VO2 was revealed in cycle-ergometer. A higher GE and economy were obtained in HS test than in cycle-ergometer exercise (p < 0.001). In both exercises, a non-significant decrease was observed in GE and economy (p > 0.05). Lower limbs fatigue was only detected after constant-load HS test.ConclusionAlthough the VO2, heart rate and EE responses were higher in cycling exercise, the constant-load HS test induced a greater VO2sc and EE raise than the cycling test in a predominantly aerobic metabolism. These results could explain a decrease observed in jump performance only after HS test. GE and economy could benefit from the eccentric phase of the HS exercise

Inertial sensors for gait monitoring and design of adaptive controllers for exoskeletons after stroke: a feasibility study

Introduction: Tuning the control parameters is one of the main challenges in robotic gait therapy. Control strategies that vary the control parameters based on the user’s performance are still scarce and do not exploit the potential of using spatiotemporal metrics. The goal of this study was to validate the feasibility of using shank-worn Inertial Measurement Units (IMUs) for clinical gait analysis after stroke and evaluate their preliminary applicability in designing an automatic and adaptive controller for a knee exoskeleton (ABLE-KS).Methods: First, we estimated the temporal (i.e., stride time, stance, and swing duration) and spatial (i.e., stride length, maximum vertical displacement, foot clearance, and circumduction) metrics in six post-stroke participants while walking on a treadmill and overground and compared these estimates with data from an optical motion tracking system. Next, we analyzed the relationships between the IMU-estimated metrics and an exoskeleton control parameter related to the peak knee flexion torque. Finally, we trained two machine learning algorithms, i.e., linear regression and neural network, to model the relationship between the exoskeleton torque and maximum vertical displacement, which was the metric that showed the strongest correlations with the data from the optical system [r = 0.84; ICC(A,1) = 0.73; ICC(C,1) = 0.81] and peak knee flexion torque (r = 0.957).Results: Offline validation of both neural network and linear regression models showed good predictions (R2 = 0.70–0.80; MAE = 0.48–0.58 Nm) of the peak torque based on the maximum vertical displacement metric for the participants with better gait function, i.e., gait speed > 0.7 m/s. For the participants with worse gait function, both models failed to provide good predictions (R2 = 0.00–0.19; MAE = 1.15–1.29 Nm) of the peak torque despite having a moderate-to-strong correlation between the spatiotemporal metric and control parameter.Discussion: Our preliminary results indicate that the stride-by-stride estimations of shank-worn IMUs show potential to design automatic and adaptive exoskeleton control strategies for people with moderate impairments in gait function due to stroke

Valoración de un implante endomedular en la funcionalidad de los pacientes amputados femorales

Introducción La amputación de una extremidad inferior es un procedimiento quirúrgico permanente que tiene importantes secuelas funcionales, psicológicas y sociales que pueden influir en la calidad de vida de la persona con amputación. El porcentaje de amputaciones femorales se sitúa en Europa alrededor de un 20-35% del total de amputaciones de la extremidad inferior. El 75% de todas las amputaciones de la extremidad inferior ocurren en pacientes mayores de 65 años al igual que ocurre en Estados Unidos. Diversos estudios han demostrado que los pacientes desarticulados de rodilla consumen menos oxígeno en la marcha y la osteoporosis del muñón es inferior que los de nivel femoral. Objetivo del estudio El objetivo de este estudio es la evaluación de la funcionalidad de pacientes amputados de nivel femoral con un implante que permite el apoyo distal del muñón y la mejora de los parámetros de dolor, calidad de vida, control y estabilidad del muñón, aumentar la densidad mineral ósea y disminuir el gasto energético respecto al uso del encaje convencional, en personas que han sufrido una amputación del miembro inferior por encima de la rodilla. Material y métodos Se ha llevado a cabo un estudio experimental prospectivo no aleatorizado de tipo antes - después realizado en el Hospital de Mataró en 10 pacientes amputados femorales tras la colocación de un implante de titanio entre 1 de marzo de 2011 a 1 de marzo de 2013. Se obtuvo el informe favorable del Comité de Ética del Hospital de Mataró para este estudio y todos los pacientes firmaron un consentimiento informado previo al inicio del estudio. Resultados La media de la edad fue de 50,3 ±16,3 años, con una mayor proporción de hombres participantes 6 (60%). La media de evolución de la amputación fue de 96,9 ± 96,3 meses, amputándose más la extremidad derecha 6 (60%). La etiología más frecuente de la amputación fue la traumática en 6 pacientes (40%). Todos los pacientes habían sido amputados en el tercio medio del fémur. Tras los 14 meses de seguimiento del procedimiento quirúrgico los pacientes incrementaron de forma significativa los metros recorridos en la prueba de 2 MWT obteniendo una media de 122,5 metros (p=0,008) y de la velocidad, pasando de 49,2 m/s previa a la intervención a 61,3 m/s a los 14 meses (p=0,008).También hubo una mejora del dolor en el muñón tras la cirugía (2,9 vs 0,4 p=0,04) y en la utilización de la prótesis en número de horas al día (10,1h vs 12,9 h p=0,01). Conclusiones Los resultados de nuestro estudio muestran una mejora de la capacidad funcional valorado en el total de metros recorridos y velocidad de marcha evaluados mediante la prueba de los 2 MWT, en pacientes amputados, principalmente de causa vascular a los 14 meses de ser intervenidos quirúrgicamente realizándose un implante femoral.Introduction Lower-limb amputation is a permanent surgical procedure that leads to a series of physical, psychological and social consequences that may affect the quality of life of the amputee.The percentage of transfemoral amputations in Europe is estimated in 20-35% of all lower limb amputations. Around 75% of the individuals who require an amputation of the lower limb are over 65 years old. Several studies have shown that individuals with a knee disarticulation have less oxygen consumption during gait performing and have less residual limb osteoporosis than individuals with a transfemoral lower limb amputation. Objective of the study The objective of this study was to investigate the functional level of individuals with a transfemoral amputation and an implant that allows distal support to the residual limb, as well as to investigate the clinical improvement in terms of pain, quality of life, residual limb control and stability, improvement of the bone mineral density and decrease of the energy expenditure when comparing with the use of a conventional socket in individuals with an above knee amputation. Materials and methods This is an experimental prospective non randomized study before-and-after intervention type developed at the Hospital de Mataró in 10 individuals with transfemoral amputation after a titanium implant placement between March 1st,2011 and March 1st, 2013. The local Ethics Committee of Hospital de Mataró approved the study and patients gave informed consent before being enrolled as participants. Results The average age was 50,3 ±16,3 years, with a higher proportion of men participating 6 (60%). The average of time since lower limb amputation was 96,9 ± 96,3 months, most of them, amputation of the right lower limb 6 (60%). The most prevalent aetiology of amputation was traumatic in 6 participants (60%). All participants had been amputated in the middle third of the femur. At the end of the 14 months of follow-up, participants significantly improved the total of meters walked in the 2 MWT, the mean was 122,5 meters (p=0,008) and they also improved the speed of gait, from 49,2 m/s before intervention to 61,3 m/s 14 months after (p=0,008). An improvement in pain was observed too after surgery (2,9 vs 0,4 p=0,04) and the number of hours using the prosthesis also improved after intervention (10,1h vs 12,9 h p=0,01). Conclusions The results of our study show an improvement in the functional capability in terms of number of meters walked and speed of gait using the 2MWT, in individuals with a lower limb amputation mainly secondary to peripheral vascular disease, 14 months after surgery for a femoral implant placement

Valoración de un implante endomedular en la funcionalidad de los pacientes amputados femorales

Introducción La amputación de una extremidad inferior es un procedimiento quirúrgico permanente que tiene importantes secuelas funcionales, psicológicas y sociales que pueden influir en la calidad de vida de la persona con amputación. El porcentaje de amputaciones femorales se sitúa en Europa alrededor de un 20-35% del total de amputaciones de la extremidad inferior. El 75% de todas las amputaciones de la extremidad inferior ocurren en pacientes mayores de 65 años al igual que ocurre en Estados Unidos. Diversos estudios han demostrado que los pacientes desarticulados de rodilla consumen menos oxígeno en la marcha y la osteoporosis del muñón es inferior que los de nivel femoral. Objetivo del estudio El objetivo de este estudio es la evaluación de la funcionalidad de pacientes amputados de nivel femoral con un implante que permite el apoyo distal del muñón y la mejora de los parámetros de dolor, calidad de vida, control y estabilidad del muñón, aumentar la densidad mineral ósea y disminuir el gasto energético respecto al uso del encaje convencional, en personas que han sufrido una amputación del miembro inferior por encima de la rodilla. Material y métodos Se ha llevado a cabo un estudio experimental prospectivo no aleatorizado de tipo antes - después realizado en el Hospital de Mataró en 10 pacientes amputados femorales tras la colocación de un implante de titanio entre 1 de marzo de 2011 a 1 de marzo de 2013. Se obtuvo el informe favorable del Comité de Ética del Hospital de Mataró para este estudio y todos los pacientes firmaron un consentimiento informado previo al inicio del estudio. Resultados La media de la edad fue de 50,3 ±16,3 años, con una mayor proporción de hombres participantes 6 (60%). La media de evolución de la amputación fue de 96,9 ± 96,3 meses, amputándose más la extremidad derecha 6 (60%). La etiología más frecuente de la amputación fue la traumática en 6 pacientes (40%). Todos los pacientes habían sido amputados en el tercio medio del fémur. Tras los 14 meses de seguimiento del procedimiento quirúrgico los pacientes incrementaron de forma significativa los metros recorridos en la prueba de 2 MWT obteniendo una media de 122,5 metros (p=0,008) y de la velocidad, pasando de 49,2 m/s previa a la intervención a 61,3 m/s a los 14 meses (p=0,008).También hubo una mejora del dolor en el muñón tras la cirugía (2,9 vs 0,4 p=0,04) y en la utilización de la prótesis en número de horas al día (10,1h vs 12,9 h p=0,01). Conclusiones Los resultados de nuestro estudio muestran una mejora de la capacidad funcional valorado en el total de metros recorridos y velocidad de marcha evaluados mediante la prueba de los 2 MWT, en pacientes amputados, principalmente de causa vascular a los 14 meses de ser intervenidos quirúrgicamente realizándose un implante femoral.Introduction Lower-limb amputation is a permanent surgical procedure that leads to a series of physical, psychological and social consequences that may affect the quality of life of the amputee.The percentage of transfemoral amputations in Europe is estimated in 20-35% of all lower limb amputations. Around 75% of the individuals who require an amputation of the lower limb are over 65 years old. Several studies have shown that individuals with a knee disarticulation have less oxygen consumption during gait performing and have less residual limb osteoporosis than individuals with a transfemoral lower limb amputation. Objective of the study The objective of this study was to investigate the functional level of individuals with a transfemoral amputation and an implant that allows distal support to the residual limb, as well as to investigate the clinical improvement in terms of pain, quality of life, residual limb control and stability, improvement of the bone mineral density and decrease of the energy expenditure when comparing with the use of a conventional socket in individuals with an above knee amputation. Materials and methods This is an experimental prospective non randomized study before-and-after intervention type developed at the Hospital de Mataró in 10 individuals with transfemoral amputation after a titanium implant placement between March 1st,2011 and March 1st, 2013. The local Ethics Committee of Hospital de Mataró approved the study and patients gave informed consent before being enrolled as participants. Results The average age was 50,3 ±16,3 years, with a higher proportion of men participating 6 (60%). The average of time since lower limb amputation was 96,9 ± 96,3 months, most of them, amputation of the right lower limb 6 (60%). The most prevalent aetiology of amputation was traumatic in 6 participants (60%). All participants had been amputated in the middle third of the femur. At the end of the 14 months of follow-up, participants significantly improved the total of meters walked in the 2 MWT, the mean was 122,5 meters (p=0,008) and they also improved the speed of gait, from 49,2 m/s before intervention to 61,3 m/s 14 months after (p=0,008). An improvement in pain was observed too after surgery (2,9 vs 0,4 p=0,04) and the number of hours using the prosthesis also improved after intervention (10,1h vs 12,9 h p=0,01). Conclusions The results of our study show an improvement in the functional capability in terms of number of meters walked and speed of gait using the 2MWT, in individuals with a lower limb amputation mainly secondary to peripheral vascular disease, 14 months after surgery for a femoral implant placement

Ventilatory efficiency during constant-load test at lactate threshold intensity: endurance versus resistance exercises

There is a lack of evidence about the ventilatory efficiency in resistance exercises despite the key role played in endurance exercises. This study aimed to compare the cardiorespiratory, metabolic responses and ventilatory efficiency between half-squat (HS) and cycle ergometer exercises during a constant-load test at the lactate threshold (LT) intensity. Eighteen healthy male participants were randomly assigned in a crossover design to carry out HS or cycle ergometer tests. For the three HS tests, a one repetition maximum (1RM) test was performed first to determine the load (kg) corresponding to the 1RM percentages. In the second test, the incremental HS exercise was carried out to establish the load (kg) at the LT intensity. Finally, a constant-load HS test was performed at the LT intensity. The first cycle ergometer test was incremental loading to determine the intensity in watts corresponding to the LT, followed by a constant-load test at the LT intensity. A recovery time of 48 hours between each test was established. During both constant-load test, cardiorespiratory and metabolic responses were monitored. A significant exercise mode x time interaction effect was only detected in oxygen uptake (VO2), heart rate, and blood lactate (p 0.05). Ventilation (VE) and carbon dioxide were highly correlated (p <0.001) in the cycle ergometer (r = 0.892) and HS (r = 0.915) exercises. In the VO2 efficiency slope (OUES), similarly significant and high correlations (p <0.001) were found between VO2 and log10 VE in the cycle ergometer (r = 0.875) and in the HS (r = 0.853) exercise. Although the cardioventilatory responses were greater in the cycle ergometer test as compared to HS exercise, ventilatory efficiency was very similar between the two exercise modalities in a predominantly aerobic metabolism