Gross efficiency and cycling performance: a review.

Efficiency, the ratio of work generated to the total metabolic energy cost, has been suggested to be a key determinant of endurance cycling performance. The purpose of this brief review is to evaluate the influence of gross efficiency on cycling power output and to consider whether or not gross efficiency can be modified. In a re-analysis of data from five separate studies, variation in gross efficiency explained ~30% of the variation in power output during cycling time-trials. Whilst other variables, notably VO2max and lactate threshold, have been shown to explain more of the variance in cycling power output, these results confirm the important influence of gross efficiency. Case study, cross-sectional, longitudinal, and intervention research designs have all been used to demonstrate that exercise training can enhance gross efficiency. Whilst improvements have been seen with a wide range of training types (endurance, strength, altitude), it would appear that high intensity training is the most potent stimulus for changes in gross efficiency. In addition to physiological adaptations, gross efficiency might also be improved through biomechanical adaptations. However, ‘intuitive’ technique and equipment adjustments may not always be effective. For example, whilst ‘pedalling in circles’ allows pedalling to become mechanically more effective, this technique does not result in short term improvements in gross efficiency

More than metrics: The role of socio- environmental factors in determining the success of athlete monitoring

The perceived value of athlete monitoring systems (AMS) has recently been questioned. Poor perceptions of AMS are important, because where practitioners lack confidence in monitoring their ability to influence programming, and performance is likely diminished. To address this, researchers have primarily sought to improve factors related to monitoring metrics, e.g., validity rather than socio-environmental factors, e.g., buy-in. Seventy-five practitioners (response rate: n = 30) working with Olympic and Paralympic athletes were invited to take part in a survey about their perceptions of AMS value. Fifty-two per cent (n = 13) was confident in the sensitivity of their athlete self-report measures, but only 64% (n = 16), indicated their monitoring was underpinned by scientific evidence. A scientific base was associated with improved athlete feedback (r S (23) = 0.487, p =0.014*) and feedback correlated with athlete monitoring adherence (r S (22) = 0.675, p = &lt;0.001**). If athletes did not complete their monitoring, 52% (n = 13) of respondents felt performance might be compromised. However, most respondents 56% (n = 14), had worked with internationally successful athlete(s) who did not complete their monitoring. While AMS can be a useful tool to aid performance optimisation, its potential value is not always realised. Addressing socio-environmental factors alongside metric-factors may improve AMS efficacy. </p

The Effect of Cycling Intensity on Cycling Economy During Seated and Standing Cycling

BACKGROUND: Previous research has shown that cycling in a standing position reduces cycling economy compared with seated cycling. It is unknown whether the cycling intensity moderates the reduction in cycling economy while standing. PURPOSE: The aim was to determine whether the negative effect of standing on cycling economy would be decreased at a higher intensity. METHODS: Ten cyclists cycled in 8 different conditions. Each condition was either at an intensity of 50% or 70% of maximal aerobic power, at a gradient of 4% or 8% and in the seated or standing cycling position. Cycling economy and muscle activation level of 8 leg muscles were recorded. RESULTS: There was an interaction between cycling intensity and position for cycling economy (P = 0.03), the overall activation of the leg muscles (P = 0.02) and the activation of the lower leg muscles (P = 0.05). The interaction showed decreased cycling economy when standing compared with seated cycling, but the difference was reduced at higher intensity. The overall activation of the leg muscles and the lower leg muscles respectively increased and decreased, but the differences between standing and seated cycling were reduced at higher intensity. CONCLUSIONS: Cycling economy was lower during standing cycling than seated cycling, but the difference in economy diminishes when cycling intensity increases. Activation of the lower leg muscles did not explain the lower cycling economy while standing. The increased overall activation therefore suggests that increased activation of the upper leg muscles explains part of the lower cycling economy while standing

RELIABILITY OF A TRUNK MOUNTED ACCELEROMETER WHEN DETERMINING GAIT PARAMETERS IN PEOPLE WITH STROKE

Wearable sensors and accelerometers can objectively and reliably assess gait parameters in both healthy individuals and stroke patients. The purpose of this study was to determine whether a wireless tri-axial accelerometer is reliable when measuring spatio-temporal gait parameters in patients with stroke. Thirty-one chronic stroke patients (age: 59.5±13.6 years; time since stroke: 28.1±17.8 months) completed three repeated walks along a 10m flat walkway whilst wearing a trunk mounted accelerometer (BTS G-Walk) secured around the waist of the participant over the L5 vertebrae. Outcome measures included cadence, speed, stride length, %stride length/height, gait cycle duration, step length, stance and swing phase duration, single and double support duration for both symptomatic and asymptomatic lower limbs where relevant. Reliability was assessed via intraclass correlation coefficient (ICC), standard error of the mean (SEM) and smallest detectable change (SDC) values. ICCs were \u3e 0.75 for all parameters, excluding step length on the asymptomatic side (ICC = 0.70). SEM and the SDC were marginally larger for the symptomatic limb than the asymptomatic limb for gait cycle duration and step length, but smaller for all other outcomes. The study showed that the BTS G-Walk is a reliable tool for measuring spatio-temporal parameters in patients with stroke. Physiotherapists and clinicians often prefer detailed information on gait ability. As advanced technologies could help with specific goals relating to gait performance, such devices could be reliably implemented as an alternative to the gold standard in clinical and community settings to monitor patients outside of a lab-based environment

Visual change detection on tunnel linings

We describe an automated system for detecting, localising, clustering and ranking visual changes on tunnel surfaces. The system is designed to provide assistance to expert human inspectors carrying out structural health monitoring and maintenance on ageing tunnel networks. A three-dimensional tunnel surface model is first recovered from a set of reference images using Structure from Motion techniques. New images are localised accurately within the model and changes are detected versus the reference images and model geometry. We formulate the problem of detecting changes probabilistically and evaluate the use of different feature maps and a novel geometric prior to achieve invariance to noise and nuisance sources such as parallax and lighting changes. A clustering and ranking method is proposed which efficiently presents detected changes and further improves the inspection efficiency. System performance is assessed on a real data set collected using a low-cost prototype capture device and labelled with ground truth. Results demonstrate that our system is a step towards higher frequency visual inspection at a reduced cost.The authors gratefully acknowledge the support by Toshiba Research Europe.This is the accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s00138-014-0648-8

Variability in Laboratory vs. Field Testing of Peak Power, Torque, and Time of Peak Power Production Among Elite Bicycle Motocross Cyclists

The aim of this study was to ascertain the variation in elite male bicycle motocross (BMX) cyclists' peak power, torque, and time of power production during laboratory and field-based testing. Eight elite male BMX riders volunteered for the study, and each rider completed 3 maximal sprints using both a Schoberer Rad Messtechnik (SRM) ergometer in the laboratory and a portable SRM power meter on an Olympic standard indoor BMX track. The results revealed a significantly higher peak power (p <= 0.001, 34 ± 9%) and reduced time of power production (p <= 0.001, 105 ± 24%) in the field tests when compared with laboratory-derived values. Torque was also reported to be lower in the laboratory tests but not to an accepted level of significance (p = 0.182, 6 ± 8%). These results suggest that field-based testing may be a more effective and accurate measure of a BMX rider's peak power, torque, and time of power production

The Relationship between Skinfold and Ultrasound Measures of Subcutaneous Fat in Untrained Healthy Males

Ultrasound measurement of adipose tissue offers an alternative measure of body composition with less technical skill requirement than skinfolds. However, the relationship between skinfold and ultrasound measurements of adipose tissue is uncertain. The aim of this study was to compare these measures in a healthy untrained male population. One hundred male participants (aged 18–40 years) of varying body compositions had skinfold measures taken at the biceps, triceps and front thigh sites. Ultrasound measures were also taken at the same sites using B-wave ultrasound with a linear probe in the transverse plane. Strong, significant (p &lt; 0.01), positive correlations were observed between skinfold and ultrasound measures at the biceps (r = 0.828), triceps (r = 0.813), and front thigh (r = 0.888) sites. However, there was significant (p &lt; 0.01) variance between the techniques at all measurement sites. Whilst skinfold and ultrasound measures of adipose tissue have good linear agreement, skinfolds are consistently higher at all sites indicating a difference in the nature of the tissue measured via each technique. The exact nature of the relationship should be established on a population-specific basis