Competition Between Desired Competitive Result, Tolerable Homeostatic Disturbance, and Psychophysiological Interpretation Determines Pacing Strategy.

Scientific interest in pacing goes back >100 years. Contemporary interest, both as a feature of athletic competition and as a window into understanding fatigue, goes back >30 years. Pacing represents the pattern of energy use designed to produce a competitive result while managing fatigue of different origins. Pacing has been studied both against the clock and during head-to-head competition. Several models have been used to explain pacing, including the teleoanticipation model, the central governor model, the anticipatory-feedback-rating of perceived exertion model, the concept of a learned template, the affordance concept, the integrative governor theory, and as an explanation for "falling behind." Early studies, mostly using time-trial exercise, focused on the need to manage homeostatic disturbance. More recent studies, based on head-to-head competition, have focused on an improved understanding of how psychophysiology, beyond the gestalt concept of rating of perceived exertion, can be understood as a mediator of pacing and as an explanation for falling behind. More recent approaches to pacing have focused on the elements of decision making during sport and have expanded the role of psychophysiological responses including sensory-discriminatory, affective-motivational, and cognitive-evaluative dimensions. These approaches have expanded the understanding of variations in pacing, particularly during head-to-head competition.

Association of osteoarthritis risk factors with knee and hip pain in a population-based sample of 29-59 year olds in Denmark: a cross-sectional analysis.

BACKGROUND: This study aimed to a) describe the prevalence of knee and hip osteoarthritis risk factors in a population of 29-59 year old individuals, b) estimate the association between persistent knee/hip pain and osteoarthritis risk factors, and c) describe the prevalence of osteoarthritis risk factors, including specific biomechanical risk factors, in individuals with prolonged persistent knee or hip pain. METHODS: Participants completed the "Early Detection and Prevention" pilot study questionnaire, including items on presence of knee/hip pain within the last month and osteoarthritis risk factors. Individuals reporting knee/hip problems completed a second questionnaire, including items about most problematic joint and specific biomechanical osteoarthritis risk factors. After describing the prevalence of persistent knee/hip pain and osteoarthritis risk factors among respondents stratified for sex and age, logistic regression was used to estimate the strength of associations between osteoarthritis risk factors and presence of knee/hip pain. The prevalence of prolonged persistent pain (i.e. knee/hip pain reported at both questionnaires) and osteoarthritis risk factors among respondents with prolonged persistent knee and hip pain, were described. RESULTS: Two thousand six hundred sixty-one respondents completed the first survey. The one-month prevalence of persistent knee/hip pain was 27%. Previous knee/hip injury was associated with persistent knee/hip pain for both sexes in all age groups, while a family history of osteoarthritis was associated with persistent knee/hip pain in all age groups except for 29-39 year old men. A higher BMI was associated with persistent knee/hip pain in 40-59 year old women, and 50-59 year old men. Eight hundred sixty seven respondents completed the second questionnaire. Knee/hip injuries and surgeries were more common in individuals with prolonged persistent knee than hip pain. CONCLUSIONS: Knee/hip pain within the last month was frequent among individuals aged 29-59 years. Multiple known osteoarthritis risk factors were associated with presence of knee/hip pain. Joint injury and previous surgery were more common in individuals with knee than hip pain. The results support the notion that joint injury and overweight during early adulthood are signs of a trajectory towards symptomatic osteoarthritis later in life and may help earlier identification of groups at high risk of future symptomatic osteoarthritis. TRIAL REGISTRATION: ClinicalTrials.gov ( NCT02797392 ). Registered April 29,2016.

Effect of knee unloading shoes on regional plantar forces in people with symptomatic knee osteoarthritis - an exploratory study.

BACKGROUND: Knee 'unloading' footwear can reduce the external knee adduction moment in people with knee osteoarthritis, yet effects of these shoes on regional plantar forces are unknown. We evaluated the effects of unloading shoes on in-shoe regional plantar forces, and whether measures of foot posture and/or mobility moderate these effects in people with symptomatic knee osteoarthritis. METHODS: In this exploratory study 21 participants underwent testing while wearing knee unloading shoes (ASICS GEL-Melbourne OA) and conventional shoes in random order. Peak total forces were compared across conditions for: lateral heel, medial heel, lateral forefoot, and medial forefoot. Arch index, centre of pressure position and medial-lateral heel peak force ratio were also evaluated. Foot posture, foot mobility magnitude and navicular drop were separately added to the mixed linear model to investigate if these modified the effect of footwear on outcomes. RESULTS: Unloading shoes significantly increased lateral heel and lateral forefoot force (12.9 and 20.2% respectively, all P < 0.001), with concurrent decreases in the medial heel (8.9%, P = 0.001) and medial forefoot (9.9%, P = 0.005). Unloading shoes significantly shifted the centre of pressure anteriorly (4.7%, P < 0.001) and laterally (5.6%, P = 0.034), but did not affect the arch index (8.7%, P = 0.093). Foot posture, foot mobility magnitude and navicular drop did not moderate the effect of footwear on outcomes. CONCLUSION: Compared to conventional shoes, unloading shoes caused a lateral shift in foot pressure and force patterns. Although these effects were not moderated by foot posture, FMM or navicular drop, variability in the individual increases in lateral heel force suggests participant characteristics other than foot posture may play a role. TRIAL REGISTRATION: ACTRN12613000851763. Registered 02 August 2013.

Association of malalignment, muscular dysfunction, proprioception, laxity and abnormal joint loading with tibiofemoral knee osteoarthritis - a systematic review and meta-analysis.

BACKGROUND: To investigate (1) the association of specific biomechanical factors with knee osteoarthritis and knee osteoarthritis development, and (2) the impact of other relevant risk factors on this association. METHODS: MEDLINE, EMBASE, CINAHL and SPORTDiscus were searched up until April 2017. Studies were included if they fulfilled the following criteria: the study 1) assessed the association of a biomechanical factor with knee osteoarthritis, or knee osteoarthritis development; 2) reported on skeletal malalignment, muscular dysfunction, impaired proprioception, laxity and abnormal loading during gait; 3) was a cohort study with participants developing knee osteoarthritis and participants not developing knee osteoarthritis, or a case-control or cross-sectional study with participants with knee osteoarthritis and without knee osteoarthritis. Risk of bias was assessed with the QUIPS tool and meta-analyses were performed using random effects models. RESULTS: Of 6413 unique studies identified, 59 cross-sectional studies were eligible for meta-analyses (9825 participants, 5328 with knee osteoarthritis). No cohort studies fulfilled the inclusion criteria. Compared with healthy controls, patients with knee osteoarthritis have higher odds of having lower muscle strength, proprioception deficits, more medial varus-valgus laxity and less lateral varus-valgus laxity. Patients with medial knee osteoarthritis have higher odds of having a higher knee adduction moment than healthy controls. Level of evidence was graded as 'very low' to 'moderate' quality. Due to large between study differences moderation of other risk factors on biomechanical risk factors could not be evaluated. CONCLUSIONS: Patients with knee osteoarthritis are more likely to display a number of biomechanical characteristics. The causal relationship between specific biomechanical factors and the development of knee osteoarthritis could not be determined as no longitudinal studies were included. There is an urgent need for high quality, longitudinal studies to evaluate the impact of specific biomechanical factors on the development of knee osteoarthritis. TRIAL REGISTRATION: (PROSPERO ID: CRD42015025092 ).

Analgesic use in patients with knee and/or hip osteoarthritis referred to an outpatient center: a cross-sectional study within the Amsterdam Osteoarthritis Cohort.

Although analgesics are widely recommended in current guidelines, underuse and inadequate prescription of analgesics seem to result in suboptimal treatment effects in patients with knee and/or hip osteoarthritis (OA). This study aimed (i) to describe the use of analgesics; and (ii) to determine factors that are related to analgesic use in patients with knee and/or hip OA referred to an outpatient center. A cross-sectional study with data from 656 patients with knee and/or hip OA referred to an outpatient center (Amsterdam Osteoarthritis (AMS-OA) cohort) was conducted. Self-reported use of analgesic (yes/no) was administered and subdivided into acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs, including coxibs) and opioids. Logistic regression analyses were performed to analyze the association between analgesic use and disease-related, predisposing and enabling factors. Analgesic use was reported by 63% of the patients, with acetaminophen, NSAIDs and opioid use reported by 50, 30 and 12%, respectively. Factors related to analgesic use were higher pain severity, longer duration of symptoms, higher radiographic hip OA severity, overweight/obesity and psychological distress. These factors explained 21% of the variance of analgesic use. More than one-third of patients with established knee and/or hip OA referred to an outpatient center did not use any analgesics. Although multiple, mostly disease-related associated factors were found, analgesic use remained predominantly unexplained. Our study seems to indicate that prescription of analgesics should be guided more dominantly by clinical symptoms and needs, and preceded by a thorough shared decision-making process between patient and physician.

Biomechanical factors associated with the development of tibiofemoral knee osteoarthritis: protocol for a systematic review and meta-analysis.

INTRODUCTION: Altered biomechanics, increased joint loading and tissue damage, might be related in a vicious cycle within the development of knee osteoarthritis (KOA). We have defined biomechanical factors as joint-related factors that interact with the forces, moments and kinematics in and around a synovial joint. Although a number of studies and systematic reviews have been performed to assess the association of various factors with the development of KOA, a comprehensive overview focusing on biomechanical factors that are associated with the development of KOA is not available. The aim of this review is (1) to identify biomechanical factors that are associated with (the development of) KOA and (2) to identify the impact of other relevant risk factors on this association. METHODS AND ANALYSIS: Cohort, cross-sectional and case-control studies investigating the association of a biomechanical factor with (the development of) KOA will be included. MEDLINE, EMBASE, CINAHL and SPORTDiscus will be searched from their inception until August 2015. 2 reviewers will independently screen articles obtained by the search for eligibility, extract data and score risk of bias. Quality of evidence will be evaluated. Meta-analysis using random effects model will be applied in each of the biomechanical factors, if possible. ETHICS AND DISSEMINATION: This systematic review and meta-analysis does not require ethical approval. The results of this systematic review and meta-analysis will be disseminated through publications in peer-reviewed journals and presentations at (inter)national conferences. TRIAL REGISTRATION NUMBER: CRD42015025092.

Optimization of Analgesics for Greater Exercise Therapy Participation Among Patients With Knee Osteoarthritis and Severe Pain: A Feasibility Study.

OBJECTIVE: Severe pain in patients with knee osteoarthritis (OA) hampers the ability to exercise. A protocol for the standardized optimization of analgesics in combination with exercise therapy was developed. The purpose of this protocol was to reduce pain, thereby allowing the patient to participate in exercise therapy. The objective of the present study was to evaluate the feasibility and outcome of the protocol. METHODS: Forty-nine patients with knee OA and severe knee pain (numerical rating scale for pain ≥7) were included. Analgesics were prescribed following an incremental protocol. After 6 weeks, a 12-week exercise therapy program was added. Information about analgesic use and exercise therapy content was recorded. Knee pain and activity limitations were assessed at baseline, after 6 weeks, and after 18 weeks. RESULTS: Statistically significant improvements in pain and activity limitations were found in intent-to-treat analysis after 6 weeks of analgesic use and after the intervention was completed. Mean improvements from baseline were 30% (P < 0.001) for pain and 17% (P < 0.001) for activity limitations after the intervention was completed. Seventy-eight percent of the patients were able to exercise according to the protocol. In these patients, exercise therapy following 6 weeks of analgesic use resulted in a further improvement of activity limitations of 10% (P = 0.004). CONCLUSION: The combined intervention of standardized analgesic prescription and exercise therapy allows most patients with knee OA and severe pain to participate in exercise therapy, leading to reduction of pain and activity limitations. These promising results need to be confirmed in a randomized controlled trial.