371 resultados para bicycle ergometry
Resumo:
This study investigated the effect of crank configuration on muscle activity and torque production during submaximal arm crank ergometry. Thirteen non-specifically trained male participants volunteered. During the research trials they completed a warm-up at 15 W before two 3-min exercise stages were completed at 50 and 100 W; subjects used either a synchronous or asynchronous pattern of cranking. During the final 30-s of each submaximal exercise stage electromyographic and torque production data were collected. After the data had been processed each parameter was analysed using separate 2-way ANOVA tests with repeated measures. The activity of all muscles increased in line with external workload, although a shift in the temporal pattern of muscle activity was noted between crank configurations. Patterns of torque production during asynchronous and synchronous cranking were distinct. Furthermore, peak, minimum and delta (peak-minimum) torque values were different (P < 0.05) between crank configurations at both workloads. For example, at 100 W, peak torque using synchronous [19.6 (4.3) Nm] cranking was higher (P < 0.05) compared to asynchronous [16.8 (1.6) Nm] cranking. In contrast minimum torque was lower (P < 0.05) at 100 W using synchronous [4.8 (1.7) Nm] compared to asynchronous [7.3 (1.2) Nm] cranking. There was a distinct bilateral asymmetry in torque production during asynchronous cranking with the dominant transmitting significantly more force to the crank arm. Taken together, these preliminary data demonstrate the complex nature of muscle activity during arm crank ergometry performed with an asynchronous or synchronous crank set-up. Further work is required to determine how muscle activity (EMG activity) and associated patterns of torque production influence physiological responses and functional capacity during arm crank ergometry.
Resumo:
The aim of this study was to examine the effects of cadence and power output on physiological and biomechanical responses to incremental arm-crank ergometry (ACE). Ten male subjects (mean +/- SD age, 30.4 +/-5.4 y; height, 1.78 +/-0.07 m; mass, 86.1 +/-14.2 kg) undertook 3 incremental ACE protocols to determine peak oxygen uptake (VO2 peak; mean of 3 tests: 3.07 +/- 0.17 L.min-1) at randomly assigned cadences of 50, 70, or 90 r.min-1. Heart rate and expired air were continually monitored. Central (RPE-C) and local (RPE-L) ratings of perceived exertion were recorded at volitional exhaustion. Joint angles and trunk rotation were analysed during each exercise stage. During submaximal power outputs of 50, 70, and 90 W, oxygen consumption (VO2) was lowest for 50 r.min-1 and highest for 90 r.min-1 (p < 0.01). VO2 peak was lowest during 50 r.min-1 (2.79 +/-0.45 L.min-1; p < 0.05) when compared with both 70 r.min-1 and 90 r.min-1 (3.16 +/-0.58, 3.24 +/-0.49 L.min-1, respectively; p > 0.05). The difference between RPE-L and RPE-C at volitional exhaustion was greatest during 50 r.min-1 (2.9 +/- 1.6) when compared with 90 r.min-1 (0.9 +/- 1.9, p < 0.05). At VO2 peak, shoulder range of motion (ROM) and trunk rotation were greater for 50 and 70 r.min-1 when compared with 90 r.min-1 (p < 0.05). During submaximal power outputs, shoulder angle and trunk rotation were greatest at 50 r.min-1 when compared with 90 r.min-1 (p < 0.05). VO2 was inversely related to both trunk rotation and shoulder ROM during submaximal power outputs. The results of this study suggest that the greater forces required at lower cadences to produce a given power output resulted in greater joint angles and range of shoulder and trunk movement. Greater isometric contractions for torso stabilization and increased cost of breathing possibly from respiratory-locomotor coupling may have contributed increased oxygen consumption at higher cadences.
Resumo:
OBJECTIVE: To study the effect of myopia and spectacle wear on bicycle-related injuries in rural Chinese students. Myopia is common among Chinese students but few studies have examined its effect on daily activities. METHODS: Data on visual acuity, refractive error, current spectacle wear, and history of bicycle use and accidents during the past 3 years were sought from 1891 students undergoing eye examinations in rural Guangdong province. RESULTS: Refractive and accident data were available for 1539 participants (81.3%), among whom the mean age was 14.6 years, 52.5% were girls, 26.8% wore glasses, and 12.9% had myopia of less than -4 diopters in both eyes. More than 90% relied on bicycles to get to school daily. A total of 2931 accidents were reported by 423 participants, with 68 requiring medical attention. Male sex (odds ratio, 1.55; P < .001) and spectacle wear (odds ratio, 1.38; P = .04) were associated with a higher risk of accident, but habitual visual acuity and myopia were unassociated with the crash risk, after adjusting for age, sex, time spent riding, and risky riding behaviors. CONCLUSION: These results may be consistent with data on motor vehicle accidents implicating peripheral vision (potentially compromised by spectacle wear) more strongly than central visual acuity in mediating crash risk.
Resumo:
This investigation aimed to explore the effects of inert sugar-free drinks described as either ‘performance enhancing’ (placebo) or ‘fatigue inducing’ (nocebo) on peak minute power (PMP;W) during incremental arm crank ergometry (ACE). Twelve healthy, non-specifically trained individuals volunteered to take part. A single-blind randomised controlled trial with repeated measures was used to assess for differences in PMP;W, oxygen uptake, heart rate (HR), minute ventilation, respiratory exchange ratio (RER) and subjective reports of local ratings of perceived exertion (LRPE) and central ratings of perceived exertion (CRPE), between three separate, but identical ACE tests. Participants were required to drink either 500 ml of a ‘sports performance’ drink (placebo), a ‘fatigue-inducing’ drink (nocebo) or water prior to exercise. The placebo caused a significant increase in PMP;W, and a significant decrease in LRPE compared to the nocebo (p=0.01; p=0.001) and water trials (p=0.01). No significant differences in PMP;W between the nocebo and water were found. However, the nocebo drink did cause a significant increase in LRPE (p=0.01). These results suggest that the time has come to broaden our understanding of the placebo and nocebo effects and their potential to impact sports performance.
Resumo:
This investigation aimed to explore the effects of inert sugar-free drinks described as either ‘performance enhancing’ (placebo) or ‘fatigue inducing’ (nocebo) on peak minute power (PMP;W) during incremental arm crank ergometry (ACE). Twelve healthy, non-specifically trained individuals volunteered to take part. A single-blind randomised controlled trial with repeated measures was used to assess for differences in PMP;W, oxygen uptake, heart rate (HR), minute ventilation, respiratory exchange ratio (RER) and subjective reports of local ratings of perceived exertion (LRPE) and central ratings of perceived exertion (CRPE), between three separate, but identical ACE tests. Participants were required to drink either 500 ml of a ‘sports performance’ drink (placebo), a ‘fatigue-inducing’ drink (nocebo) or water prior to exercise. The placebo caused a significant increase in PMP;W, and a significant decrease in LRPE compared to the nocebo (p=0.01; p=0.001) and water trials (p=0.01). No significant differences in PMP;W between the nocebo and water were found. However, the nocebo drink did cause a significant increase in LRPE (p=0.01). These results suggest that the time has come to broaden our understanding of the placebo and nocebo effects and their potential to impact sports performance.
Resumo:
The article presents the “LungoSolofrana” project, carried out during the course “Urban and Mobility” in the academic year 2009/2010, held during the bachelor in Environmental Engineering at the University of Naples “Federico II”. The work has also been chosen as a finalist at the “UrbanPromo 2010” contest, the urban and territorial marketing event sponsored by the National Institute of Urban Planning and Urbit which was held in Venice in 2010. The project consists in a green mobility proposal, developed with an approach based on the integration of the environmental redevelopment of a portion of river Solofrana, located in the Salerno Province, and of the renewal of seven local stations of the railway line Mercato San Severino – Nocera Inferiore, including the realization of a cycle-path network for the natural environment fruition. Furthermore the work drew attention to the local and regional administration. The main intent of the project is to integrate sustainable mobility themes with the environment recovery in a territory affected by high environmental troubles. The area includes the municipalities of Nocera Inferiore, Nocera Superiore, Mercato San Severino, Castel San Giorgio and Roccapiemonte, situated in Salerno’s province, with a total population about 114.000 (font Demo ISTAT 2010). The area extension is about 84,30 sqkm and it is crossed by river Solofrana that is the central point of the project idea. The intervention strategy is defined in two kinds of actions: internal and external rail station interventions. The external rail station interventions regard the construction of pedestrian-cycle paths with the scope of increasing the spaces dedicated to cyclists and to pedestrians along the river Solofrana sides and to connect the urban areas with the railway station. In this way, it’s also possible to achieve an urban requalification of the interested area. On the other side, the interventions inside the station , according to Transit Oriented Development principles, aim at redeveloping common spaces with the insertion of new activities and at realizing new automatic cycle parks covered by photovoltaic panels. The project proposal consists of the urban regeneration of small railway stations along the route-Nocera-Codola Mercato San Severino in the province of Salerno, through interventions aimed at improving pedestrian accessibility. The project involves in particular the construction of pedestrian paths protected access to the station and connecting with neighboring towns and installation of innovative bike parking stations in elevation, covering surfaces coated with solar panels and spaces information. The project is aimed to propose a new model of sustainable transport for small and medium shifts as an alternative to private transportation
Resumo:
A photograph of the Owls Bicycle Club in the year 1889. The men are in the rear of the Watson memorial with St. Joseph's convent/orphanage and St. Catharines Cathedral in the background. There are 21 men on bicycle including Stanley G. Smith (second row, fourth from the left).