Andrew J Callaway

Increasing walking among older people: A test of behaviour change techniques using factorial randomised N-of-1 trials

Objective: Evaluations of techniques to promote physical activity usually adopt a randomised controlled trial (RCT). Such designs inform how a technique performs on average but cannot be used for treatment of individuals. Our objective was to conduct the first N-of-1 RCTs of behaviour change techniques with older people and test the effectiveness of the techniques for increasing walking within individuals. Design: Eight adults aged 60–87 were randomised to a 2 (goal-setting vs. active control) × 2 (self-monitoring vs. active control) factorial RCT over 62 days. The time series data were analysed for each single case using linear regressions. Main outcome measures: Walking was objectively measured using pedometers. Results: Compared to control days, goal-setting increased walking in 4 out of 8 individuals and self-monitoring increased walking in 7 out of 8 individuals. While the probability for self-monitoring to be effective in 7 out of 8 participants was beyond chance (p = .03), no intervention effect was significant for individual participants. Two participants had a significant but small linear decrease in walking over time. Conclusion: We demonstrate the utility of N-of-1 trials for advancing scientific enquiry of behaviour change and in practice for increasing older people’s physical activity.

Linear Acceleration Measurement Utilizing Inter-Instrument Synchronization: A Comparison between Accelerometers and Motion-Based Tracking Approaches

Where as video cameras are a reliable and established technology for the measurement of kinematic parameters, accelerometers are increasingly being employed for this type of measurement due to their ease of use, performance, and comparatively low cost. However, the majority of accelerometer-based studies involve a single channel due to the difficulty associated with synchronizing multiple accelerometer channels. The authors of this article outline a method to synchronize multiple accelerometers using a maxima detection method. Results are presented that demonstrate the effectiveness of the new synchronization method with 52 of 54 recorded data sets showing no time lag error and two tests showing an error of .04 sec. Inter-instrument and instrument-video correlations are all greater than r = .94 (p < .01), with inter-instrument precision (Root Mean Square Error; RMSE) ≈ .1ms−2, demonstrating the efficacy of the technique. In conclusion, the new technique offers a robust solution, giving further support to the movement toward wider adoption of accelerometer-based performance measurement systems in sports science.

Measuring kinematic variables in front crawl swimming using accelerometers: a validation study.

Objective data on swimming performance is needed to meet the demands of the swimming coach and athlete. The purpose of this study is to use a multiple inertial measurement units to calculate Lap Time, Velocity, Stroke Count, Stroke Duration, Stroke Rate and Phases of the Stroke (Entry, Pull, Push, Recovery) in front crawl swimming. Using multiple units on the body, an algorithm was developed to calculate the phases of the stroke based on the relative position of the body roll. Twelve swimmers, equipped with these devices on the body, performed fatiguing trials. The calculated factors were compared to the same data derived to video data showing strong positive results for all factors. Four swimmers required individual adaptation to the stroke phase calculation method. The developed algorithm was developed using a search window relative to the body roll (peak/trough). This customization requirement demonstrates that single based devices will not be able to determine these phases of the stroke with sufficient accuracy.

Identification of temporal factors related to shot performance for indoor recurve archery

ABSTRACT The purpose of this study was to investigate the temporal phases of the archery shot cycle that distinguish the arrows distance from centre, in an attempt to understand critical factors that affect performance. Fifteen archers of varying ability each performed 30 shots at 18 m. Fourteen potential predictor variables were measured for statistical modelling by stepwise multiple linear regression. The results show that pre-shot time (pre-performance routine), follow-through time (post-performance routine), aiming time, speed of the arrow and the %variation in clicker-release time, account for 7.7% of the variation in predicting shot performance. The results have implications for practice demonstrating factors that coaches should focus on to develop their athletes. Further work on pre-, but more importantly, post-performance routines are needed generally within sport research as they are lacking and have been shown to be important contributing factors in a number of sports.

Inter-Rater Reliability and Criterion Validity of Scatter Diagrams as an Input Method for Marksmanship Analysis: Computerised Notational Analysis for Archery

Basic notational systems exist in many sports but may not always be formally named as such. This paper outlines the validity and reliability of using a computerised scatter diagram as an input method for the analysis of marksmanship in target sports with Archery used as an example sport. Software was created to represent a standard FITA 122cm target face. An Archer shot 72 arrows, these were measured to create coordinates of each arrow. Twelve images (6 arrows per image) were shown to 10 operators. Operators input each arrow position into the software to produce a coordinate for each arrow. The coordinates where additionally processed using marksmanship statistics, Accuracy Constant Error (ACE), Accuracy Variable Error (AVE) and Precision (Mean Radius-MR). ICC was used to test validity and PPMC to test inter-rater reliability of the raw data and error analysis on the processed data. Raw results showed strong positive correlations for validity against the measured coordinates (>.977) and high levels of inter-rater reliability(>.969). Processed results show less than 2% error to that of measured results. Systems such as this allow coach/athlete/researcher to track varying equipment setups, changes to biomechanics, physiology and psychology, allowing for continued development of athlete, sport and equipment.

The influence of lower-limb prostheses technology on Paracanoeing time-trial performance

Abstract Within the Paracanoeing discipline, it is important to ensure that appropriate control is achieved by a paddler with a disability. However, this Paralympic Games discipline has seen very little attention to date. The aims of this study were to understand the kinematic impact to a paracanoeist when not utilizing the use of a prosthetic lower-limb. A kayaker with a uni-lateral transfemoral amputation completed several 200 m maximal efforts both with and without their prosthesis. When the prosthetic limb was removed, there were significant differences found in stroke rate, stroke speed, stroke length and overall power output. Sagittal and frontal video analysis demonstrated the residual limb movements when paddling and indicated where support would be required to improve the kayak’s control. It is recommended that those with lower-limb absence wishing to paddle a kayak competitively utilize the use of a prostheses designed for the kayaking environment that supports the residual limb at both the upper and inner thigh and the distal end. Implications for rehabilitation This paper is the first study to investigate both biomechanical and assistive technology-related issues in the new Paralympic Games sport of Paracanoeing. For participants possessing lower-limb absence, a prosthetic limb that is designed specifically for the kayaking environment is recommended when Paracanoeing to maximize efficient propulsion. Use of an ergometer and multiple 2D cameras provides practitioners the ability to optimize both the comfort and fit of a prosthetic limb. Use of an ergometer and multiple 2D cameras provides both athletes and practitioners the ability to optimize the points of human contact within a kayak to ensure comfort and control.

Sprint prostheses used at the Paralympics: a proposal for an assessment method to maintain fairness

Background: Unique to sport with a disability such as those performed at the Paralympics, the need to improve the performance of lower limb prostheses can conflict with the need to provide an equal opportunity to win whilst still needing to encourage and maximise participation. Objectives: This paper extends previous research by attempting to propose a method suitable for sports governing bodies to help any functional assessment of sprinting lower limb prosthesis technology in the future. Study Design: The study comprises two elements: 1) A historical review and evaluation of drop jump assessment techniques. 2) A pilot test of a candidate using two mechanically different lower limb regions. Methods: A unilateral drop jump technique is assessed historically as an evaluation technique for sprinters with a lower-limb amputation. Further, a unilateral drop jump using mechanically altered lower limbs is piloted. Results: The historical review provides no evidence to suggest that this technique is not suitable for athlete participants. The pilot trials show a statistically stable and repeatable method of demonstrating a mechanical deficiency of one limb to another. Six jumps are suitable to obtain stable results but the mechanical behaviour of one limb may eventually change based on accumulated fatigue. Conclusions: The unilateral drop jump is shown to be viable for application to an athlete population with a lower limb unilateral amputation. Clinical relevance This paper develops previous sports stakeholder research and pilots an assessment strategy to provide a functional limb-to-limb comparison of the same lower limb region. This would potentially be used by both prosthetists and the sport’s governing body to help maintain fairness in the sport as prosthesis technology develops.