Abnormal loading of the knee joint contributes to the pathogenesis of knee osteoarthritis. Gait retraining is a noninvasive intervention that aims to reduce knee loads by providing audible, visual, or haptic feedback of gait parameters. The computational expense of joint contact force prediction has limited real-time feedback to surrogate measures of the contact force, such as the knee adduction moment. We developed a method to predict knee joint contact forces using motion analysis and a statistical regression model that can be implemented in near real-time. Gait waveform variables were deconstructed using principal component analysis, and a linear regression was used to predict the principal component scores of the contact force waveforms. Knee joint contact force waveforms were reconstructed using the predicted scores. We tested our method using a heterogenous population of asymptomatic controls and subjects with knee osteoarthritis. The reconstructed contact force waveforms had mean (SD) root mean square differences of 0.17 (0.05) bodyweight compared with the contact forces predicted by a musculoskeletal model. Our method successfully predicted subject-specific shape features of contact force waveforms and is a potentially powerful tool in biofeedback and clinical gait analysis.
Christopher M. Saliba, Allison L. Clouthier, Scott C.E. Brandon, Michael J. Rainbow and Kevin J. Deluzio
Carlo Di Brina, Roberto Averna, Paola Rampoldi, Serena Rossetti and Roberta Penge
This pilot study is to investigate the influence of a developmental coordination disorder (DCD) comorbidity in a group of children with learning disability (LD). Reading and writing were assessed to investigate if the coexistence of a motor impairment can worsen writing quality, speed, and reading accuracy. A sample of 33 LD children (aged 7–11 years) was divided in two subgroups, on the base of their scores on the Movement Assessment Battery for Children: LD-only (n = 14) and LD with a comorbidity for DCD (LD–DCD, n = 19). No differences were found in handwriting speed, but significant differences were found in handwriting quality: LD–DCD children showed a worst performance. Reading words and nonwords accuracy was more impaired in LD-only children than in LD–DCD children. Group differences suggest a poorer phonological decoding of the LD-only sample, whereas worst cursive handwriting legibility scores are typical of the motor-impaired subgroup.
Marie Lund Ohlsson, Jonas Danvind and L. Joakim Holmberg
Overuse injuries in the shoulders and lower back are hypothesized to be common in cross-country sit-skiing. Athletes with reduced trunk muscle control mainly sit with the knees higher than the hips (KH). To reduce spinal flexion, a position with the knees below the hips (KL) was enabled for these athletes using a frontal trunk support. The aim of the study was to compare the shoulder joint (glenohumeral joint) and L4-L5 joint reactions of the KL and KH sitting positions. Five able-bodied female athletes performed submaximal and maximal exercise tests in the sitting positions KL and KH on a ski ergometer. Measured pole forces and 3-dimensional kinematics served as input for inverse-dynamics simulations to compute the muscle forces and joint reactions in the shoulder and L4-L5 joint. This was the first musculoskeletal simulation study of seated double poling. The results showed that the KH position was favorable for higher performance and decreased values of the shoulder joint reactions for female able-bodied athletes with full trunk control. The KL position was favorable for lower L4-L5 joint reactions and might therefore reduce the risk of lower back injuries. These results indicate that it is hard to optimize both performance and safety in the same sit-ski.
Isaac Estevan, Sergio Gandia, Israel Villarrasa-Sapiña, José Luis Bermejo and Xavier García-Massó
This paper describes a study on postural stability and cognitive function according to the difficulty increment of a working memory task (WMT) and age group in adolescents. One hundred and twenty-three participants (13–16 years) performed single and dual tasks in a bipedal standing position while barefoot. Four trials were conducted, consisting of single and dual tasks in three progressively difficult WMT conditions (i.e., 3-, 5-, and 7-digit sequences). Friedman’s analysis of variance and Kruskal–Wallis tests were conducted to test the effect of the WMT and age group, respectively. Both the WMT and age were found to affect performance (p < .01). As the cognitive requirements increased, the adolescents were not able to maintain their performance in both balance and cognition, while postural control and cognition were found to evolve with age.
Alexander T. Latinjak
This two-study project provided a brief description of athletes’ experiences with mind wandering. Study 1 aimed to quantitatively examine mind wandering in sports, in terms of frequency, effects and perceived control. Therefore, 94 athletes (Mage = 19.51, SD = 1.65) answered a specifically designed 19-item questionnaire. The results suggested that mind wandering is a common phenomenon in sports, with both beneficial and adverse effects on performance. Study 2 aimed to qualitatively explore when athletes use mind wandering. Accordingly, 115 athletes (Mage = 22.82, SD = 3.61) described one recent mind wandering situation while practicing sport. A hierarchical content analysis was performed by the first author and confirmed by an external expert. The results indicated that mind wandering occurred in a wide range of situations in sport and physical activity. Nonetheless, it was also argued that future studies should more carefully define mind wandering to avoid confusion with related terms.
Rosanna Gilderthorp, Jan Burns and Fergal Jones
It has been shown that having intellectual disabilities impacts to reduce performance compared to athletes without this impairment. However, it has also been demonstrated that there is a not a direct link between intelligence and athletic performance. To advance elite ID sport more needs to be understood about the relationship between this impairment and sporting performance. This is vital if competition classification systems are to be based on theory and evidence. This study used the International Classification of Functioning, Disability and Health (ICF) as an approach to classification and examined the impact of multiple health problems on athletic performance. A health survey was administered to two groups of athletes with ID: elite and regional level athletes. Athletes with Down Syndrome were also identified. Overall disability scores predicted sporting performance, but not IQ or Down Syndrome. The implications of these findings are discussed with reference to the ICF framework and classification.
Carrie B. Scherzer and Justine J. Reel
In this commentary, we try to present a balanced look at the issues surrounding the implementation of the certification exam for recertification purposes. We recognize that the changes to certification are complex and varied, as were reactions by the membership of the Association for Applied Sport Psychology (AASP). As long-standing AASP members who are also certified consultants, we look at the costs, benefits, and ultimately the reality of the CMPC exam for recertification.
Fleur E.C.A. van Rens, Erika Borkoles, Damian Farrow and Remco C.J. Polman
Using a holistic perspective on athlete talent development, this study examines the impact of role strain on the life satisfaction in various life domains of junior elite Australian Rules Football players. One hundred and twelve talent-identified male Australian Rules Football players (M age = 16.8; SD = .71) completed measures of role strain and multidimensional life satisfaction. The results indicated that role strain explained twelve to twenty-four percent of the variance in life satisfaction in the players’ life domains. Experiences of role strain related to the players’ dual careers were associated with decreased life satisfaction in sport, friendships, family, yourself, and global life satisfaction domains. Situations in which the players perceived that their abilities were underutilized were also negatively associated with life satisfaction across various life domains. This study thus evidences the importance of a domain specific, holistic approach to investigate the life satisfaction in junior athletes’ dual careers.
Ralph Appleby, Paul Davis, Louise Davis and Henrik Gustafsson
Perceptions of teammates and training load have been shown to influence athletes’ physical and psychological health; however, limited research has investigated these factors in relation to burnout. Athletes (N = 140) from a variety of competitive team sports, ranging in level from regional to professional, completed questionnaires measuring individual burnout, perceptions of teammates’ burnout, and training hours per week on two occasions separated by three months. After controlling for burnout at time one, training hours were associated with athletes’ burnout and perceptions of teammates’ burnout at time two. Multilevel modeling indicated actual team burnout (i.e., the average burnout score of the individual athletes in a team) and perceived team burnout were associated with individual’s own burnout. The findings highlight that burnout is dynamic and relates to physiological stressors associated with training and psychological perceptions of teammates’ burnout. Future research directions exploring potential social influences on athlete burnout are presented.
Marcus Börjesson, Carolina Lundqvist, Henrik Gustafsson and Paul Davis
The purpose of the study was to investigate the influence of flotation REST upon skilled and less skilled golfers’ anxiety in terms of physiological indicators of stress, self-rated anxiety scores, muscle tension, and the effect on golf putting. Prior to performing the putting task participants underwent a treatment of flotation REST or a period of resting in an armchair. Participants completed both treatments in a randomized order with a two-week interval. The results showed that both flotation REST and the armchair treatment reduced systolic blood pressure and heart rate, with no differences between treatments or athlete skill levels. No significant differences between treatments were revealed regarding self-ratings, level of muscle tension or putting precision. The results indicate that flotation REST may be useful for reducing negative symptoms related to stress and anxiety in general; however, no support for direct positive effects on golf performance were found.