A Biopsychosocial Model for Understanding Training Load, Fatigue, and Musculoskeletal Sport Injury in University Athletes: A Scoping Review.

ABSTRACT: McClean, ZJ, Pasanen, K, Lun, V, Charest, J, Herzog, W, Werthner, P, Black, A, Vleuten, RV, Lacoste, E, and Jordan, MJ. A biopsychosocial model for understanding training load, fatigue, and musculoskeletal sport injury in university athletes: A scoping review. J Strength Cond Res 38(6): 1177-1188, 2024-The impact of musculoskeletal (MSK) injury on athlete health and performance has been studied extensively in youth sport and elite sport. Current research examining the relationship between training load, injury, and fatigue in university athletes is sparse. Furthermore, a range of contextual factors that influence the training load-fatigue-injury relationship exist, necessitating an integrative biopsychosocial model to address primary and secondary injury prevention research. The objectives of this review were (a) to review the scientific literature examining the relationship between training load, fatigue, and MSK injury in university athletes and (b) to use this review in conjunction with a transdisciplinary research team to identify biopsychosocial factors that influence MSK injury and develop an updated, holistic biopsychosocial model to inform injury prevention research and practice in university sport. Ten articles were identified for inclusion in this review. Key findings were an absence of injury surveillance methodology and contextual factors that can influence the training load-fatigue-MSK injury relationship. We highlight the inclusion of academic load, social load, and mental health load as key variables contributing to a multifactorial, gendered environmental, scientific inquiry on sport injury and reinjury in university sport. An integrative biopsychosocial model for MSK injury in university sport is presented that can be used to study the biological, psychological, and social factors that modulate injury and reinjury risk in university athletes. Finally, we provide an example of how causal inference can be used to maximize the utility of longitudinally collected observational data that is characteristic of sport performance research in university sport.

The influence of skeletal muscle mitochondria and sex on critical torque and performance fatiguability in humans.

Critical torque (CT) represents the highest oxidative steady state for intermittent knee extensor exercise, but the extent to which it is influenced by skeletal muscle mitochondria and sex is unclear. Vastus lateralis muscle biopsy samples were collected from 12 females and 12 males -matched for relative maximal oxygen uptake normalized to fat-free mass (FFM) (F: 57.3 (7.5) ml (kg FFM)-1  min-1 ; M: 56.8 (7.6) ml (kg FFM)-1  min-1 ; P = 0.856) - prior to CT determination and performance fatiguability trials. Males had a lower proportion of myosin heavy chain (MHC) I isoform (40.6 (18.4)%) compared to females (59.5 (18.9)%; P = 0.021), but MHC IIa and IIx isoform distributions and protein markers of mitochondrial content were not different between sexes (P > 0.05). When normalized to maximum voluntary contraction (MVC), the relative CT (F: 42.9 (8.3)%; M: 37.9 (9.0)%; P = 0.172) and curvature constant, W' (F: 26.6 (11.0) N m s (N m)-1 ; M: 26.4 (6.5) N m s (N m)-1 ; P = 0.962) were not significantly different between sexes. All protein biomarkers of skeletal muscle mitochondrial content, as well as the proportion of MHC I isoform, positively correlated with relative CT (0.48 < r < 0.70; P < 0.05), and the proportion of MHC IIx isoform correlated positively with relative W' (r = 0.57; P = 0.007). Indices of performance fatiguability were not different between males and females for MVC- and CT-controlled trials (P > 0.05). Greater mitochondrial protein abundance was associated with attenuated declines in potentiated twitch torque for exercise at 60% MVC (P < 0.05); however, the influence of mitochondrial protein abundance on performance fatiguability was reduced when exercise was prescribed relative to CT. Whether these findings translate to whole-body exercise requires additional research. KEY POINTS: The quadriceps critical torque represents the highest intensity of intermittent knee extensor exercise for which an oxidative steady state is attainable, but its relationship with skeletal muscle mitochondrial protein abundance is unknown. Matching males and females for maximal oxygen uptake relative to fat-free mass facilitates investigations of sex differences in exercise physiology, but studies that have compared critical torque and performance fatiguability during intermittent knee extensor exercise have not ensured equal aerobic fitness between sexes. Skeletal muscle mitochondrial protein abundance was correlated with critical torque and fatigue resistance for exercise prescribed relative to maximum voluntary contraction but not for exercise performed relative to the critical torque. Differences between sexes in critical torque, skeletal muscle mitochondrial protein abundance and performance fatiguability were not statistically significant. Our results suggest that skeletal muscle mitochondrial protein abundance may contribute to fatigue resistance by influencing the critical intensity of exercise.

Time course and fibre type-dependent nature of calcium-handling protein responses to sprint interval exercise in human skeletal muscle.

Sprint interval training (SIT) causes fragmentation of the skeletal muscle sarcoplasmic reticulum Ca2+ release channel, ryanodine receptor 1 (RyR1), 24 h post-exercise, potentially signalling mitochondrial biogenesis by increasing cytosolic [Ca2+ ]. Yet, the time course and skeletal muscle fibre type-specific patterns of RyR1 fragmentation following a session of SIT remain unknown. Ten participants (n = 4 females; n = 6 males) performed a session of SIT (6 × 30 s 'all-out' with 4.5 min rest after each sprint) with vastus lateralis muscle biopsy samples collected before and 3, 6 and 24 h after exercise. In whole muscle, full-length RyR1 protein content was significantly reduced 6 h (mean (SD); -38 (38)%; P < 0.05) and 24 h post-SIT (-30 (48)%; P < 0.05) compared to pre-exercise. Examining each participant's largest response in pooled samples, full-length RyR1 protein content was reduced in type II (-26 (30)%; P < 0.05) but not type I fibres (-11 (40)%; P > 0.05). Three hours post-SIT, there was also a decrease in sarco(endo)plasmic reticulum Ca2+ ATPase 1 in type II fibres (-23 (17)%; P < 0.05) and sarco(endo)plasmic reticulum Ca2+ ATPase 2a in type I fibres (-19 (21)%; P < 0.05), despite no time effect for either protein in whole muscle samples (P > 0.05). PGC1A mRNA content was elevated 3 and 6 h post-SIT (5.3- and 3.7-fold change from pre, respectively; P < 0.05 for both), but peak PGC1A mRNA expression was not significantly correlated with peak RyR1 fragmentation (r2  = 0.10; P > 0.05). In summary, altered Ca2+ -handling protein expression, which occurs primarily in type II muscle fibres, may influence signals for mitochondrial biogenesis as early as 3-6 h post-SIT in humans. KEY POINTS: Sprint interval training (SIT) has been shown to cause fragmentation of the sarcoplasmic reticulum calcium-release channel, ryanodine receptor 1 (RyR1), 24 h post-exercise, which may act as a signal for mitochondrial biogenesis. In this study, the time course was examined of RyR1 fragmentation in human whole muscle and pooled type I and type II skeletal muscle fibres following a single session of SIT. Full-length RyR1 protein content was significantly lower than pre-exercise by 6 h post-SIT in whole muscle, and fragmentation was detectable in type II but not type I fibres, though to a lesser extent than in whole muscle. The peak in PGC1A mRNA expression occurred earlier than RyR1 fragmentation. The increased temporal resolution and fibre type-specific responses for RyR1 fragmentation provide insights into its importance to mitochondrial biogenesis in humans.

Efficacy of Hip Strengthening Exercises Compared With Leg Strengthening Exercises on Knee Pain, Function, and Quality of Life in Patients With Knee Osteoarthritis.

OBJECTIVE: The purpose of this study was to compare the efficacy of hip and leg strengthening exercise programs on knee pain, function, and quality of life (QOL) of patients with knee osteoarthritis (KOA). DESIGN: Single-Blinded Randomized Clinical Trial. SETTING: Patients with KOA. PARTICIPANTS: Male and female subjects were recruited from patients referred to the University of Calgary Sport Medicine Center and from newspaper advertisements. INTERVENTIONS: Thirty-seven and 35 patients with KOA were randomly assigned to either a 12-week hip or leg strengthening exercise program, respectively. Both exercise programs consisted of strengthening and flexibility exercises, which were completed 3 to 5 days a week. The first 3 weeks of exercise were supervised and the remaining 9 weeks consisted of at-home exercise. MAIN OUTCOME MEASURES: Knee Injury and Osteoarthritis Score (KOOS) and Western Ontario McMaster Arthritis Index (WOMAC) questionnaires, 6-minute walk test, hip and knee range of motion (ROM), and hip and leg muscle strength. RESULTS: Statistically and clinically significant improvements in the KOOS and WOMAC pain subscale scores were observed in both the hip and leg strengthening programs. There was no statistical difference in the change in scores observed between the 2 groups. Equal improvements in the KOOS and WOMAC function and QOL subscales were observed for both programs. There was no change in hip and knee ROM or hip and leg strength in either group. CONCLUSIONS: Isolated hip and leg strengthening exercise programs seem to similarly improve knee pain, function, and QOL in patients with KOA. CLINICAL RELEVANCE: The results of this study show that both hip and leg strengthening exercises improve pain and QOL in patients with KOA and should be incorporated into the exercise prescription of patients with KOA.

Contraction intensity affects NIRS-derived skeletal muscle oxidative capacity but not its relationships to mitochondrial protein content or aerobic fitness.

To further refine the near-infrared spectroscopy (NIRS)-derived measure of skeletal muscle oxidative capacity in humans, we sought to determine whether the exercise stimulus intensity affected the τ value and/or influenced the magnitude of correlations with in vitro measures of mitochondrial content and in vivo indices of exercise performance. Males (n = 12) and females (n = 12), matched for maximal aerobic fitness per fat-free mass, completed NIRS-derived skeletal muscle oxidative capacity tests for the vastus lateralis following repeated contractions at 40% (τ40) and 100% (τ100) of maximum voluntary contraction, underwent a skeletal muscle biopsy of the same muscle, and performed multiple intermittent isometric knee extension tests to task failure to establish critical torque (CT). The value of τ100 (34.4 ± 7.0 s) was greater than τ40 (24.2 ± 6.9 s, P < 0.001), but the values were correlated (r = 0.688; P < 0.001). The values of τ40 (r = -0.692, P < 0.001) and τ100 (r = -0.488, P = 0.016) correlated with myosin heavy chain I percentage and several markers of mitochondrial content, including COX II protein content in whole muscle (τ40: r = -0.547, P = 0.006; τ100: r = -0.466, P = 0.022), type I pooled fibers (τ40: r = -0.547, P = 0.006; τ100: r = -0.547, P = 0.006), and type II pooled fibers (τ40: r = -0.516, P = 0.009; τ100: r = -0.635, P = 0.001). The value of τ40 (r = -0.702, P < 0.001), but not τ100 (r = -0.378, P = 0.083) correlated with critical torque (CT); however, neither value correlated with W' (τ40: r = 0.071, P = 0.753; τ100: r = 0.054, P = 0.812). Overall, the NIRS method of assessing skeletal muscle oxidative capacity is sensitive to the intensity of skeletal muscle contraction but maintains relationships to whole body fitness, isolated limb critical intensity, and mitochondrial content regardless of intensity.NEW & NOTEWORTHY Skeletal muscle oxidative capacity measured using near-infrared spectroscopy (NIRS) was lower following high-intensity compared with low-intensity isometric knee extension contractions. At both intensities, skeletal muscle oxidative capacity was correlated with protein markers of mitochondrial content (in whole muscle and pooled type I and type II muscle fibers) and critical torque. These findings highlight the importance of standardizing contraction intensity while using the NIRS method with isometric contractions and further demonstrate its validity.

The influence of sex, hemoglobin mass, and skeletal muscle characteristics on cycling critical power.

Critical power (CP) represents an important threshold for exercise performance and fatiguability. We sought to determine the extent to which sex, hemoglobin mass (Hbmass), and skeletal muscle characteristics influence CP. Before CP determination (i.e., 3-5 constant work rate trials to task failure), Hbmass and skeletal muscle oxidative capacity (τ) were measured and vastus lateralis (VL) muscle biopsy samples were collected from 12 females and 12 males matched for aerobic fitness relative to fat-free mass (FFM) [means (SD); V̇o2max: 59.2 (7.7) vs. 59.5 (7.1) mL·kg·FFM-1·min-1, respectively]. Males had a significantly greater CP than females in absolute units [225 (28) vs. 170 (43) W; P = 0.001] but not relative to body mass [3.0 (0.6) vs. 2.7 (0.6) W·kg·BM-1; P = 0.267] or FFM [3.6 (0.7) vs. 3.7 (0.8) W·kg·FFM-1; P = 0.622]. Males had significantly greater W' (P ≤ 0.030) and greater Hbmass (P ≤ 0.016) than females, regardless of the normalization approach; however, there were no differences in mitochondrial protein content (P = 0.375), τ (P = 0.603), or MHC I proportionality (P = 0.574) between males and females. Whether it was expressed in absolute or relative units, CP was positively correlated with Hbmass (0.444 ≤ r ≤ 0.695; P < 0.05), mitochondrial protein content (0.413 ≤ r ≤ 0.708; P < 0.05), and MHC I proportionality (0.506 ≤ r ≤ 0.585; P < 0.05), and negatively correlated with τ when expressed in relative units only (-0.588 ≤ r ≤ -0.527; P < 0.05). Overall, CP was independent of sex, but variability in CP was related to Hbmass and skeletal muscle characteristics. The extent to which manipulations in these physiological parameters influence CP warrants further investigation to better understand the factors underpinning CP.NEW & NOTEWORTHY In males and females matched for aerobic fitness [maximal oxygen uptake normalized to fat-free mass (FFM)], absolute critical power (CP) was greater in males, but relative CP (per kilogram body mass or FFM) was similar between sexes. CP correlated with hemoglobin mass, mitochondrial protein content, myosin heavy chain type I proportion, and skeletal muscle oxidative capacity. These findings demonstrate the importance of matching sexes for aerobic fitness, but further experiments are needed to determine causality.

Diminished cartilage-lubricating ability of human osteoarthritic synovial fluid deficient in proteoglycan 4: Restoration through proteoglycan 4 supplementation.

OBJECTIVE: The purposes of this study were 1) to quantify the proteoglycan 4 (PRG4) and hyaluronan (HA) content in synovial fluid (SF) from normal donors and from patients with chronic osteoarthritis (OA) and 2) to assess the cartilage boundary-lubricating ability of PRG4-deficient OA SF as compared to that of normal SF, with and without supplementation with PRG4 and/or HA. METHODS: OA SF was aspirated from the knee joints of patients with symptomatic chronic knee OA prior to therapeutic injection. PRG4 concentrations were measured using a custom sandwich enzyme-linked immunosorbent assay (ELISA), and HA concentrations were measured using a commercially available ELISA. The molecular weight distribution of HA was measured by agarose gel electrophoresis. The cartilage boundary-lubricating ability of PRG4-deficient OA SF, PRG4-deficient OA SF supplemented with PRG4 and/or HA, and normal SF was assessed using a cartilage-on-cartilage friction test. Two friction coefficients (µ) were calculated: static (µ(static, Neq) ) and kinetic (<µ(kinetic, Neq) >) (where N(eq) represents equilibrium axial load and angle brackets indicate that the value is an average). RESULTS: The mean ± SEM PRG4 concentration in normal SF was 287.1 ± 31.8 µg/ml. OA SF samples deficient in PRG4 (146.5 ± 28.2 µg/ml) as compared to normal were identified and selected for lubrication testing. The HA concentration in PRG4-deficient OA SF (mean ± SEM 0.73 ± 0.08 mg/ml) was not significantly different from that in normal SF (0.54 ± 0.09 mg/ml). In PRG4-deficient OA SF, the molecular weight distribution of HA was shifted toward the lower range. The cartilage boundary-lubricating ability of PRG4-deficient OA SF was significantly diminished as compared to normal (mean ± SEM <µ(kinetic, Neq) > = 0.043 ± 0.008 versus 0.025 ± 0.002; P < 0.05) and was restored when supplemented with PRG4 (<µ(kinetic, Neq) > = 0.023 ± 0.003; P < 0.05). CONCLUSION: These results indicate that some OA SF may have decreased PRG4 levels and diminished cartilage boundary-lubricating ability as compared to normal SF and that PRG4 supplementation can restore normal cartilage boundary lubrication function to these OA SF.

Eating patterns and composition of meals and snacks in elite Canadian athletes.

The purpose of this study was to determine the meal- and snack-eating frequency and the nutritional composition of each eating occasion of Canadian high-performance athletes during training. Athletes from 8 Canadian Sport Centres prospectively completed 3-d dietary records including all food, fluid, and supplements consumed. The time of consumption and whether the consumption was a meal or snack were also identified. The dietary records were analyzed for energy (kcal) and macronutrient intake (carbohydrate, protein, and fat) and compared based on gender, age, meal vs. snack, and training vs. rest days. Three hundred twenty-four athletic subjects (64% female and 36% male) completed the study. On average, the athletes ate 4.8 ± 0.8 times daily. Nearly all athletes consumed 3 daily meals of breakfast (98.9%), lunch (97.9%), and dinner (98.7%), with few having snacks: 57%, 71.6%, and 58.1% of athletes consumed an a.m., p.m., and evening snack, respectively. Training-day meal frequency did not differ from that during rest days; however, fewer snacks were consumed on rest days. A.m. and p.m. snacks were consumed significantly more often on training days than rest days. Overall, snacks contributed 24.3% of total daily energy intake. Few dietary variations were discovered between genders, while the youngest athletes (<18 yr) ate less often, especially their morning snack, than the older athletes. In conclusion, Canadian high-performance athletes self-adjusted their energy intakes on training vs. rest days primarily by snacking less and reducing their carbohydrate and protein intakes on rest days, yet they consistently ate regular meals.

Dietary supplementation practices in Canadian high-performance athletes.

Dietary supplementation is a common practice in athletes with a desire to enhance performance, training, exercise recovery, and health. Supplementation habits of elite athletes in western Canada have been documented, but research is lacking on supplement use by athletes across Canada. The purpose of this descriptive study was to evaluate the dietary supplementation practices and perspectives of high-performance Canadian athletes affiliated with each of the country's eight Canadian Sport Centres. Dietitians administered a validated survey to 440 athletes (63% women, 37% men; M=19.99±5.20 yr) representing 34 sports who predominantly trained≥16 hr/wk, most competing in "power" based sports. Within the previous 6 months, 87% declared having taken≥3 dietary supplements, with sports drinks, multivitamin and mineral preparations, carbohydrate sports bars, protein powder, and meal-replacement products the most prevalent supplements reported. Primary sources of information on supplementation, supplementation justification, and preferred means of supplementation education were identified. Fifty-nine percent reported awareness of current World Anti-Doping Agency legislation, and 83% subjectively believed they were in compliance with such anti-doping regulations. It was concluded that supplementation rates are not declining in Canada, current advisors on supplementation for this athletic population are not credible, and sports medicine physicians and dietitians need to consider proactive strategies to improve their influence on supplementation practices in these elite athletes.

Physical activity RX: development and implementation of physical activity counselling and prescription learning objectives for Canadian medical school curriculum.

Physical activity is an important component of health and well-being, and is effective in the prevention, management, and treatment of numerous non-communicable chronic diseases. Despite the known health benefits of physical activity in all populations, most Canadians do not meet physical activity recommendations. Physicians play a key role in assessing, counselling, and prescribing physical activity. Unfortunately, many barriers, including the lack of adequate education and training, prevent physicians from promoting this essential health behaviour. To support Canadian medical schools in physical activity curriculum development, a team of researchers, physicians, and exercise physiologists collaborated to develop a key set of learning objectives deemed essential to physician education in physical activity counselling and prescription. This commentary will review the newly developed Canadian Physical Activity Counselling Learning Objectives and give case examples of three Canadian medical schools that have implemented these learning objectives.

L'activité physique est une composante importante de la santé et du bien-être, et elle est efficace dans la prévention, la prise en charge et le traitement de nombreuses maladies chroniques non transmissibles. Malgré les bienfaits qu'on lui reconnaît pour la santé des populations, la plupart des Canadiens ne suivent pas les recommandations en matière d'exercice. Les médecins jouent un rôle clé dans l'évaluation, le counseling et la prescription de l'activité physique, mais de nombreux obstacles, dont le manque de formation adéquate, les empêchent de promouvoir cette habitude de vie essentielle pour la santé. Afin d'aider les facultés de médecine canadiennes dans l'élaboration de leur cursus sur l'activité physique, une équipe composée de chercheurs, de médecins et de physiologistes de l'exercice a collaboré à la définition d'un ensemble d'objectifs d'apprentissage jugés indispensables à la formation des médecins pour qu'ils puissent offrir des conseils sur l'activité physique et la prescrire. Ce commentaire passe en revue les nouveaux objectifs d'apprentissage en matière de counseling en activité physique et donne des exemples de cas de trois facultés de médecine canadiennes qui ont mis en œuvre ces objectifs d'apprentissage.

The effect of an exertional field-test on sport concussion assessment tool 5 subcomponents in University rugby and wrestling athletes: A pilot prospective case series.

OBJECTIVES: To evaluate how an exertional field-test impacts the Sport Concussion Assessment Tool 5 (SCAT5) subcomponents in uninjured athletes. DESIGN: Prospective case-series. SETTING: Sports medicine setting. PARTICIPANTS: A total of 37 rugby and wrestling athletes (76% female) with a median age of 19 years (range: 18-23). Twenty-one (57%) had a history of concussion. MAIN OUTCOME MEASURES: The SCAT5 was administered prior-to and following a volitionally fatiguing, field-based 30-15 Intermittent Fitness Test. The primary outcome measures included: total symptom scores and severity, standardized assessment of concussion, neurological screening, and balance errors during the modified balance error scoring system. Wilcoxon signed-rank tests examined differences in ordinal data between pre- and post-exertion with Bonferroni corrections (alpha = 0.006). Data were also stratified into time to SCAT5 administration post-exertion and compared via Cliff's Delta (d). RESULTS: The SCAT5 was administered a median of 20-min (interquartile range: 14-26-min) following exertion. No differences were found pre- and post-exertion across all SCAT5 metrics (p > 0.048). Within the post-exertion 0-10-min stratification, total symptoms and severity scores appeared to be elevated with a large effect size (d ≥ 0.64). CONCLUSIONS: While SCAT5 metrics were not statistically altered when quantified a median of 20-min following high-intensity exertion; greater symptom reporting may occur 10-min following exertion.

One-year stability of preseason Sport Concussion Assessment Tool 5 (SCAT5) values in university level collision and combative sport athletes.

OBJECTIVES: To determine the stability of the Sport Concussion Assessment Tool (SCAT) 5 between consecutive seasons in uninjured collision and combative varsity athletes. METHODS: Thirty-six athletes (19 females) were recruited to participate (wrestling [n = 12], rugby [n = 14], and hockey [n = 10]). The SCAT5 was administration at the start of the 2017 and 2018 seasons. Median baseline demographics for 2017 were as follows: age (19 years [range: 17-24 years]), height (174 cm [range: 149-195 cm]), and weight (76 kg [range: 57-118 kg]). Outcome metrics included subcomponents of the SCAT5: symptom reporting, standardized assessment of concussion (SAC), neurological screening, and balance performance measured with the modified balance error scoring system (mBESS). Wilcoxon signed-rank tests and Cronbach's alpha (α) values were calculated to determine the stability between consecutive years for the SCAT5 variables in the same cohort of athletes. Bonferroni corrections were applied for Wilcoxon signed-rank tests, where alpha = 0.006 (0.05/9). RESULTS: Between the 2017 and 2018 seasons, no differences were noted in symptom reporting (p = 0.14), SAC (p = 0.32), neurological screening (p = 0.98), and balance performance on the mBESS (p = 0.01). The Cronbach's alpha displayed unacceptable to questionable levels of within-subject stability (range: α = 0.34-0.70) for all subcomponents, except months in reverse order (α = 0.92). CONCLUSIONS: While no statistical differences were present for all SCAT5 subcomponent metrics between 2017 and 2018 baselines, all but one displayed unacceptable to questionable stability (α ≤ 0.70) when retested one year later. Further research is needed to understand the appropriate time duration baseline SCAT5 values can reliably be utilized within longitudinal studies; as well as the normal variation of SCAT5 reporting/scoring.

The effect of high-intensity physical exertion on measures of cervical spine, vestibular/ocular-motor screening, and vestibulo-ocular reflex function in university level collision and combative sport athletes.

OBJECTIVES: To examine how high-intensity physical exertion affects clinical measures of cervical spine (CSp), vestibular/ocular motor screen (VOMS), and vestibulo-ocular reflex (VOR) function. DESIGN: Case series. SETTING: Sports Medicine Centre. PARTICIPANTS: A total of 37 athletes consented to participate (22 rugby, 15 wrestling; 9 men, 28 women; median age = 19 years [range 17-23 years]). MAIN OUTCOME MEASURES: Outcome measures included tests of CSp (cervical flexor endurance, head perturbation test, cervical flexion rotation test and anterolateral strength), VOR (head thrust test and dynamic visual acuity [DVA]), and a quantified version of the VOMS. These metrics were assessed prior to and after completing the 30-15 Intermittent Fitness Test. Bland-Altman plots and Wilcoxon signed-rank tests were utilized to analyze the data using an alpha of p < 0.004. RESULTS: Cervical anterolateral strength (kg) was reduced post-exertion on the left (z = 3.87; p < 0.001), but not on the right between conditions (z = -1.49; p = 0.14). Athletes reported increased dizziness (z = -3.55; p = 0.004) and had reduced DVA following exertion (z = -2.78; p < 0.001). All other metrics were not significantly different following exertion (p > 0.011). CONCLUSION: Reduced performance on DVA, decreased left-anterolateral strength, and increased dizziness occurred following high-intensity exertion in varsity collision and combative athletes, which has implications for sideline screening for sport-related concussion.

Evaluation of nutritional intake in Canadian high-performance athletes.

OBJECTIVE: To determine the nutritional intake of Canadian high-performance athletes. DESIGN: Prospective survey study. SETTING: Canadian sport center athletes. PARTICIPANTS: Three hundred twenty-four high-performance athletes (114 males and 201 females; mean age 21.3 +/- 13 years) from 8 Canadian sport centers participated in the study. INTERVENTION: Subjects prospectively completed 3-day dietary records, reporting all food, fluid, and supplement consumption. MAIN OUTCOME MEASURES: Dietary records were analyzed for total calories, macronutrients, and micronutrients for food alone and food plus supplements for all subjects collectively and according to gender and competitive event. RESULTS: Average daily energy intake was 2533 +/- 843 Kcal/day with males consuming more calories than females (2918 +/- 927 and 2304 +/- 713 Kcal/day, respectively; P < 0.05). Both genders consumed below recommended levels. Carbohydrate, protein, and fat accounted for 53%, 19%, and 28% of daily calorie intake, respectively. Average daily carbohydrate and protein intake was 5.1 +/- 1.8 and 1.8 +/- 0.6 g/kg body weight, respectively. Protein intake, but not carbohydrate intake, met recommendations. Supplementation significantly increased athletes' energy, total carbohydrate, protein, and fat intake. Of 17 micronutrients assessed, intake ranged between 120% and 366% of recommended daily intake with food alone and between 134% to 680% of recommended daily intake with supplements. CONCLUSIONS: Canadian high-performance athletes do not consume adequate energy or carbohydrates. However, their intake of micronutrients exceed current recommended daily intakes, even when supplements are not considered, indicating that athletes make high-quality food choices. Supplementation significantly increased energy, macronutrient, and micronutrient intake.

Adapting the Dynamic, Recursive Model of Sport Injury to Concussion: An Individualized Approach to Concussion Prevention, Detection, Assessment, and Treatment.

SYNOPSIS: The risk factors of concussion may be categorized as intrinsic (internal factors specific to the individual) or extrinsic (external factors related to the environment or sport). Identifying these factors is part of an individualized, patient-centered approach to prevention, assessment, and management of concussion. In most cases, the symptoms of concussion resolve in the initial few days following the injury, and a strategy involving a gradual return to sport and school is recommended. When symptoms persist for longer than 7 to 10 days, a multifaceted interdisciplinary assessment to guide treatment is recommended. This article applies the dynamic, recursive model of sport injury to sport-related concussion and summarizes the process of individualized assessment and management following concussion in athletes of all ages, with a focus on physical rehabilitation. J Orthop Sports Phys Ther 2019;49(11):799-810. doi:10.2519/jospt.2019.8926.

Foot structure and knee joint kinetics during walking with and without wedged footwear insoles.

The relationship between static foot structure characteristics and knee joint biomechanics during walking, or the biomechanical response to wedged insoles are currently unknown. In this study, 3D foot scanning, dual X-ray absorptiometry and gait analysis methods were used to determine structural parameters of the foot and assess their relation to knee joint loading and biomechanical response to wedged insoles in 30 patients with knee osteoarthritis. In multiple linear regression models, foot fat content, height of the medial longitudinal arch and static hind foot angle were not associated with the magnitude of the knee adduction moment (R2 = 0.24, p = 0.060), knee adduction angular impulse (R2 = 0.21, p = 0.099) or 3D resultant knee moment (R2 = 0.23, p = 0.073) during gait. Furthermore, these foot structure parameters were not associated with the patients' biomechanical response to medial or lateral wedge footwear insoles (all p < 0.01). These findings suggest that static foot structure is not associated with gait mechanics at the knee, and that static foot structure alone cannot be utilized to predict an individual's biomechanical response to wedged footwear insoles in patients with knee osteoarthritis.

A three dimensional approach for quantifying resultant loading at the knee.

BACKGROUND: Clinical effectiveness of lateral wedges for knee osteoarthritis is inconsistent across studies. One explanation is that knee loading is not fully described by the peak frontal-plane knee moment. The purpose of this study was to propose a 3D resultant approach to describing moments at the knee and evaluate how this moment changes in response to lateral wedges. METHODS: Walking gait analysis was performed on 20 individuals with knee osteoarthritis, in their own shoes, with and without a six millimeter lateral wedge insole. Frontal-plane and 3D resultant moments were calculated for each participant and footwear condition. Paired t-tests identified differences between footwear conditions, correlations identified relationships between frontal-plane and 3D resultant moments, and regressions assessed relationships between moments and pain. RESULTS: Significant reductions to peak frontal-plane moments (p=0.001) and 3D resultant moments at the same time point (p=0.042) were observed with lateral wedges. While an overall significant correlation was observed between change in frontal-plane moments and change in 3D resultant moments with a lateral wedge (r=0.68, p=0.001), 5/20 participants experienced disparate results where the frontal-plane moment was reduced yet the 3D moment increased. CONCLUSIONS: While lateral wedges alter frontal-plane moment magnitude, the direction of change does not always correspond to the direction of change observed in the 3D resultant moment. Thus resultant knee load may sometimes increase with lateral wedges. CLINICAL RELEVANCE: Future prospective studies should evaluate if changes in 3D resultant moments, and thus total knee load, offer an explanation as to why some participants do not experience clinical benefit from lateral wedges.

Knee angular impulse as a predictor of patellofemoral pain in runners.

BACKGROUND: Identification of mechanical factors associated with patellofemoral pain, the most prevalent running injury, is necessary to help in injury prevention, but unfortunately they remain elusive. HYPOTHESIS: Runners who develop patellofemoral pain have increased knee joint angular impulse in the frontal plane. STUDY DESIGN: Case control study; Level of evidence, 3. METHODS: A retrospective study compared knee abduction impulses of 20 patellofemoral pain patients with those of 20 asymptomatic patients. A second prospective study quantified knee angular impulses during the stance phase of running of 80 runners at the beginning of the summer running season. Epidemiologic data were then collected, recording the type and severity of injury of these runners during a 6-month running period. RESULTS: The patellofemoral pain patients in the retrospective study had significantly higher (P = .026) knee abduction impulses (17.0 +/- 8.5 Nms) than did the asymptomatic patients (12.5 +/- 5.5 Nms). Six patients developed patellofemoral pain during the prospective study. The prospective data showed that patients who developed patellofemoral pain had significantly higher (P = .042) knee abduction impulses (9.2 +/- 3.7 Nms) than did matched patients who remained uninjured (4.7 +/- 3.5 Nms). CONCLUSION: The data indicate that increased knee abduction impulses should be deemed risk factors that play a role in the development of patellofemoral pain in runners. CLINICAL RELEVANCE: Footwear and running style can influence knee angular impulse, and the appropriate manipulation of these variables may play a preventive role for patients who are predisposed to patellofemoral pain.

Reduced knee adduction moments for management of knee osteoarthritis:: A three month phase I/II randomized controlled trial.

Wedged insoles are believed to be of clinical benefit to individuals with knee osteoarthritis by reducing the knee adduction moment (KAM) during gait. However, previous clinical trials have not specifically controlled for KAM reduction at baseline, thus it is unknown if reduced KAMs actually confer a clinical benefit. Forty-eight participants with medial knee osteoarthritis were randomly assigned to either a control group where no footwear intervention was given, or a wedged insole group where KAM reduction was confirmed at baseline. KAMs, Knee Injury and Osteoarthritis Outcome Score (KOOS) and Physical Activity Scale for the Elderly (PASE) scores were measured at baseline. KOOS and PASE surveys were re-administered at three months follow-up. The wedged insole group did not experience a statistically significant or clinically meaningful change in KOOS pain over three months (p=0.173). Furthermore, there was no association between change in KAM magnitude and change in KOOS pain over three months within the wedged insole group (R2=0.02, p=0.595). Improvement in KOOS pain for the wedged insole group was associated with worse baseline pain, and a change in PASE score over the three month study (R2=0.57, p=0.007). As an exploratory comparison, there was no significant difference in change in KOOS pain (p=0.49) between the insole and control group over three months. These results suggest that reduced KAMs do not appear to provide any clinical benefit compared to no intervention over a follow-up period of three months. ClinicalTrials.gov ID Number: NCT02067208.

Injuries in short track speed skating.

BACKGROUND: Little is known about the pattern of injury in short track speed skating. PURPOSE: To investigate the incidence and characteristics of injuries in short track speed skating. STUDY DESIGN: Retrospective study. METHODS: Ninety-five of 150 elite-level skaters (63.3%) were surveyed to collect information on training and competition load as well as on injuries sustained during the 1999-2000 competitive season. Injuries were characterized in terms of anatomic location, type of injury, time loss from training and competition, and circumstance of injury (acute onset during competition, on-ice practice, off-ice training, or insidious onset). RESULTS: Sixty-one of the 95 skaters (64.2%) reported sustaining at least one injury. The knee, ankle, spine, leg, and groin were the most commonly reported sites of injury. Skaters were also asked to list previous on-ice injuries. The two most common injuries occurring on-ice before the 1999-2000 season were lacerations from the knee down (11.1%) and ankle fractures (10.2%). CONCLUSION: The results of this study suggest that there is a high incidence of injury in competitive short track speed skating.