ABSTRACT
Objective To compare the pedaling force and lower extremity electromyography (EMG) with different cadences (60, 75, 90 r/min) and diverse cycling intensities (50%, 65%, 80% POV) and study the different influence on exerciser's pedaling force and lower extremity EMG. Methods Twelve healthy males participated in this study, and underwent two stages. In stage 1 the power output test at VO2max (POV) was got by cycle ergometer. In stage 2, nine conditions (3 kinds of intensities × 3 kinds of cadences) were completed respectively by using counter-balance design to record the changes for their pedaling force and lower extremity EMG. Results The negative pedaling work was significantly increased with the cadence increasing, and the appearing time of the peak pedaling force was significantly shifted forward in the cycle. When the crank angle was at 270°, the average increase of the pedaling force with the cadence increasing could obtain 1.84 times higher. In general, the firing rate of lower extremity muscular activation would be increased with the cadence increasing. Conclusions The cadence has greater effect on the pedaling force and lower extremity EMG. The tendency of pedaling force was shifted forward and the pattern of pedaling force became smoother with the cadence increasing. There are no significant differences among the diverse intensities. Based on the pedaling efficiency in this study, the optimal cadence for untrained people should be 60 r/min.
ABSTRACT
O objetivo deste estudo foi testar uma metodologia para o ensino da técnica da pedalada do ciclismo utilizando variáveis biomecánicas para desenvolver um sistema de "feedback" visual aumentado (FVA). Participaram do estudo 19 indivíduos, sem experiência no ciclismo , divididos em grupo experimental (n = 10) e controle (n = 9). Inicialmente foi realizado um pré-teste para determinar o consumo máximo de oxigênio (VO2máx) bem como a carga de trabalho utilizada nas sessões práticas que correspondeu a 60% do VO2máx. Em seguida foram realizadas sete sessões de prática. O grupo experimental foi submetido ao FVA e o grupo controle ao "feedback" aumentado (FA). O teste de retenção mostrou um aumento de 21 % na média do índice de efetividade (IE) do grupo experimental quando comparado ao grupo controle. Os resultados mostraram que variáveis biomecánicas são apropriadas para o desenvolvimento de FVA e podem contribuir no processo de ensino-aprendizagem da técnica da pedalada do ciclismo.
The aim of this study was to test a methodology to teach the pedaling technique of cycling using biomechanics variables to develop an augmented visual feedback system (AVF). Nineteen subjects divided in two groups (experimental = 10 and control = 9) without experience in cycling were used. A pre-test was conducted to determine the maximal oxygen uptake (VO2máx) , and to establishe the work load to be used during the learning sessions which was defined to be the load that was associated with the 60% of VO2máx . Seven practice sessions were held. The experimental group was submitted to AVF and the control group to augmented feedback (AF). After the practice sessions, the retention test showed a significant increase in the index of effectiveness (IE) for the experimental group of 21% compared to the control group. These results showed that the biomechanics variables were appropriated to the development the AVF system and can contribute in the process pedaling technique learning.
El objetivo de este estudio fue probar una metodología para enseñar la técnica de el ciclismo mediante la utilización de variables biomecánicas para desarrollar un sistema de feedback visual aumentado (FVA). Fue aplicado en 19 personas sin experiencia en el ciclismo, divididos en dos grupos (experimental = 10 y control = 9). Inicialmente se realizó un pre-test para determinar el consumo máximo de oxígeno (VO2max) y la carga de trabajo utilizada en las sesiones de práctica que correspondía al 60% del VO2máx. El grupo experimental fue sometido a la FVA y el control a la feedback aumentado (FA). El ensayo de retención mostró un aumento del 21% en la media del índice de eficacia (IE) en el grupo experimental en comparación con el grupo control. Los resultados mostraron que las variables biomecánicas son apropiadas para el desarrollo de la FVA y puede contribuir al proceso de enseñanza y aprendizaje del ciclismo.
Subject(s)
Humans , Male , Adolescent , Bicycling/education , Feedback, Sensory , LearningABSTRACT
@#Objective To explore the effect of intensive pedaling training on lower limbs recovery from hemiplegia. Methods 60 hemiplegics after stroke were divided into treatment group (n=30) and control group (n=30). Both groups accepted routine rehabilitation, including physiotherapy, occupational therapy, acupuncture and electrical stimulation, while the treatment group accepted intensive pedaling training in addition. They were evaluated with Berg Balance Scale (BBS), Fugl-Meyer Assessment of lower limb (FMA-L), modified Barthel index (MBI), Functional Ambulation Category (FAC), modified Ashworth scale (MAS) before and after 8 weeks of treatment. Results The scores of BBS, FMA-L, MBI, FAC, and MAS improved in both groups after treatment (P<0.01), and improved more in the treatment group than in the control group (P<0.05). Conclusion Intensive pedaling training can further improve the lower limbs function of stroke patients with hemiplegia
ABSTRACT
En el ciclismo colombiano, las pautas de entrenamiento se ajustan a partir de datos cualitativos basados en la observación directa al deportista. Esta investigación busca mejorar ese proceso por medio de la implementación de pedales instrumentados para obtener datos cuantitativos del rendimiento del ciclista. En este artículo se presenta el diseño y construcción de un prototipo de dispositivo dinamométrico que permite la captura de datos de fuerza en el pedal durante el gesto del pedaleo. El dispositivo funciona con base en un sensor de fuerza piezorresistivo (FlexiForce®) acoplado a un arreglo mecánico específico y a un sistema de acondicionamiento de señal que entrega un voltaje proporcional a la fuerza ejercida, cuyo registro y análisis se realiza por medio de LabVIEW TM. El dispositivo permite visualizar la fuerza del pedaleo en tiempo real.
In the Colombian cycling, the training guidelines are adjusted from qualitative data based on the direct observation of the sportsman. The aim of this research was to improve this process by the implementation of instrumented pedals to collect quantitative data of the performance of the cyclist. In this article we present the design and construction of a prototype of a dynamometric device that allows the acquisition of force data in the pedal. The device works based in a piezoresistive force sensor (FlexiForce®) connected to a specific mechanical adjustment and a signal conditioning system that gives a proportional voltage to the exerted force, whose registry and analysis are made in LabVIEW TM. The device allows the visualization of the pedaling force in real time.
ABSTRACT
The purpose of this study was to examine the effects of ankle plantar and dorsal flexion on the lower extremities' dynamics and crank torque in pedaling movements. Twelve males (6 cyclists and 6 non-cyclists) pedaled at the rate of 90 and 120 rpm for a power output of 200W. Subjects were divided into two groups according to the different ankle movement patterns in one crank rotation. The first group (Gr1) showed a one time plantar and dorsal flexion movement in one rotation. The second group (Gr2) showed two plantar and dorsal flexion movements in one rotation. It was assumed that the exertion of positive plantar flexor power in the upstroke phase could provide the difference of the ankle movement patterns. The following results were shown in Gr2 as compared with Grl. 1) The positive crank torque time ratio was extended due to dorsal flexor torque produced near the top dead center. 2) Continuous muscle contraction of the same muscle was avoided and reduction in a burden was brought about due to plantar flexion in the upstroke phase. 3) Reduction of hip extensor torque was shown. These results suggest that two dorsal and plantar flexion movements in one rotation in pedaling could be a more effective pattern in terms of muscle work.
ABSTRACT
The purpose of this study was to compare the thigh muscle oxygenation state of competitive road cyclists and non-cyclists during varied pedaling frequency cycling. Six male college road cyclists (CY group) and five male students (NC group) performed four sets of cycling bouts, consisting of 2 minutes of warm up (60 rpm, 50 watts) followed by 5 minutes of pedaling (150 watts) using an electro-magnetic braked cycle ergometer at 40, 60, 90, and 120 rpm. Oxygenated hemoglobin and/or myoglobin (Oxy-Hb/Mb) and deoxygenated Hb/Mb (Deoxy-Hb/Mb) concentrations in the vastus lateralis were measured by near infrared spatially resolved spectroscopy. The Oxy-Hb/Mb level was significantly higher in the CY group than the NC group. But there was no significant intraction effect of the group and pedaling rate on the Oxy-Hb/Mb level. These results suggest that the changes in muscle oxygenation state according to pedaling cadence do not differ between cyclists and non-cyclists. And though the whole body work efficiency decreased according to increasing pedaling cadence, Oxy-Hb/Mb and Deoxy-Hb/Mb levels in the vastus lateralis remained unchanged up to 90 rpm. However, at 120 rpm, the Oxy-Hb/Mb level decreased remarkably and the Deoxy-Hb/Mb level increased. These results suggest that deoxygenation in the vastus lateralis at 120 rpm was higher than that for lower frequencies. And, conversely, oxygen uptake in the vastus lateralis might have increased steeply at 120 rpm. It may be that the maximum pedaling cadence that would not reduce work efficiency in the vastus lateralis is around 90 rpm.
ABSTRACT
The purpose of this study was to compare the effect between cyclists and noncyclists of pedal rates on ankle, knee, and hip joint torque during pedaling exercises. Six male cyclists (CY) and seven male noncyclists (NC) pedaled at 40, 60, 90 and 120 rpm with a power output of 200 W. The lower limb was modeled as three rigid segment links constrained to plane motion. Based on the Newton-Euler method, the equation for each segment was constructed and solved on a computer using pedal force, pedal, crank, and lower limb position data to calculate torque at the ankle, knee, and hip joints. The average planter flexor torque decreased with increasing pedal rates in both groups. The average knee extensor torque for CY decreased up to 90 rpm, and then leveled off at 120 rpm. These results were similar to NC. The average knee flexor torque in both groups remained steady over all pedal rates. The average hip extensor torque for CY decreased significantly up to 90 rpm where it showed the lowest value, but increased at 120 rpm. For NC, the average hip extensor torque did not decrease at 90 rpm compared with 60 rpm, and was significantly higher than CY at 120 rpm (CY : 28.1 ± 9.0 Nm, NC : 38.6 ± 6.7 Nm, p<0.05) . The average hip flexsor torque for NC at 120 rpm increased significanly from 90 rpm, and was significantly higher than CY (CY : 11.6±2.9 Nm, NC : 22.6±11.8 Nm, p<0.05) . These results suggest that it would be better for cyclists to select a pedal rate of between 90 to 110 rpm to minimize joint torque, and, as a result, reduce peripheral muscle fatigue.
ABSTRACT
Trunk motion and the mechanisms of postural control during pedaling was investigated by analyzing the lower trunk muscle activity and spinal motion.<BR>Eight healthy adult men were assigned to pedal at the rate of 60 cycles per min. with the load of 100 W, 150 W and 200 W. Muscle activity was recorded with the surface electrodes from the m. multifidus, m, iliocostalis, m. obliquus externus, m; rectus abdominis, m. rectus lemons, m. adductor longus and m. semitendinosus. Spinal motion was filmed with 8 mm video camera located 5 m behind the subject and 1 m above the floor, and five markers were attached on the midline of the spine (C 7, Th 6, Th 12, S 1, Co) .<BR>Muscle activity (iEMG) was quantified by integrating one cycle of recorded electromyogram, and significant increase was recognized in the trunk muscles and m. rectus femoris as the load increased. The angles between each segments were calculated and the largest deviation was observed in the lumbo-sacral portion. Focussing on the activity of the m. obliquus externus, four patterns of controling the trunk posture were observed, and as the load increased, the activity patterns changed in four subjects and the other four showed tremendous increase in iEMG without changing the pattern.<BR>The results sugest that the pedaling may cause relatively large motion at lambo-sacral portion of the spine, and either the change in the activity pattern or the increase in the activity level of the trunk muscles, such as m, obliquus externus, should contribute to reduce the stress on the lambo-sacral portion.