Prescribing Blood Flow Restricted Exercise: Limb Composition Influences the Pressure Required to Create Arterial Occlusion.

CONTEXT: As blood flow restriction gains popularity across different populations (eg, young and older adults) and settings (eg, clinical and sports rehabilitation), the accuracy of blood flow restricted percentage becomes crucial. We aimed to compare manually measured arterial occlusion pressure (AOP) among young adults to understand whether lower limb composition affects the pressure required to achieve AOP. The results will shed light on the adequacy of published calculations used to estimate AOP in practical and research settings. DESIGN: An observational cross-sectional study design was implemented to examine the relationship between lower limb composition, lower limb circumference, and measured AOP. METHODS: Twenty-two participants (12 males, 26 [4] y, 1.74 [0.07] m, 73.2 [12.5] kg) underwent a whole-body Dual-energy X-ray Absorptiometry scan before AOP (in millimeters of mercury) and lower limb circumference (in centimeters) were determined. In a supine position, a 10-cm wide cuff was manually inflated on the dominant leg to the point where a pulse could no longer be detected by a Doppler ultrasound of the posterior tibial artery to determine AOP. Lower limb composition (fat, muscle, and bone mass [in grams]) was obtained from the Dual-energy X-ray Absorptiometry scan. RESULTS: Lower limb muscle mass had a moderate negative relationship with AOP (r2 = .433, ß = -0.004) and a moderate positive relationship with lower limb circumference (r2 = .497, ß = 0.001). Lower limb circumference had the weakest relationship with AOP (r2 = .316, ß = 0.050) of all measures. CONCLUSIONS: The reported relationships between lower limb muscle mass, lower limb circumference, and AOP suggest that as muscle mass increases, lower limb circumference also increases, yet AOP decreases. This implies that limb circumference should not be used as the primary measure for calculating AOP within the sampled population. We recommend individually measuring AOP when implementing blood flow restriction in all exercise modalities.

Continuous blood flow restriction during repeated-sprint exercise increases peripheral but not systemic physiological and perceptual demands.

This study examined the impact of continuous blood flow restriction (BFR) during repeated-sprint exercise (RSE) on acute performance, peripheral, systemic physiological, and perceptual responses. In a randomized crossover design, 26 adult male semi-professional and amateur team-sport players completed two RSE sessions (3 sets of 5 × 5-s sprints with 25 s of passive recovery and 3 min of rest) with continuous BFR (45% arterial occlusion; excluding during between-set rest periods) or without (non-BFR). Mean and peak power output were significantly lower (p < 0.001) during BFR compared to non-BFR (dz = 0.85 and 0.77, respectively). Minimum tissue saturation index during the sprints and rest periods was significantly reduced (p < 0.001) for BFR (dz = 1.26 and 1.21, respectively). Electromyography root mean square was significantly decreased (p < 0.01) for biceps femoris and lateral gastrocnemius muscles during BFR (dz = 0.35 and 0.79, respectively), but remained unchanged for the vastus lateralis muscle in both conditions. Oxygen consumption and minute ventilation were significantly reduced (both p < 0.01) for BFR (dz = 1.46 and 0.43, respectively). Perceived limb discomfort was significantly higher (p < 0.001) for BFR (dz = 0.78). No differences (p > 0.05) in blood lactate concentration or rating of perceived exertion were observed between conditions. Blood flow-restricted RSE reduced performance and likely increased the physiological and perceptual stimulus for the periphery with greater reliance on anaerobic glycolysis, despite comparable or decreased systemic demands.

Blood flow restricted walking alters gait kinematics.

This study investigated the impact of blood flow restriction (BFR) during treadmill walking on gait kinematics. Twenty-one participants completed one familiarisation and four experimental sessions, including two walking speeds (moderate [5.0 ± 0.3km·h-1] and fast [6.4 ± 0.4km·h-1]) and two occlusion conditions (BFR [60% of arterial occlusion pressure] and unrestricted). For each exercise intensity, the BFR session was performed first. Participants were instructed to walk as long as possible, with sessions capped at 20 min. Unrestricted sessions were time-matched, and the order of exercise intensity was randomised. Kinematics were collected over 10s every minute using retro-reflective markers affixed to specific body landmarks. Ratings of perceived exertion and discomfort were collected every two minutes. Blood samples were collected from the fingertip pre-exercise and the finger and toe post-exercise, and were analysed for lactate, electrolytes, and markers of cell-membrane damage. During the BFR sessions the cuffs remained inflated while the blood samples were collected. Fast-walk BFR sessions exhibited higher anterior trunk flexion (p = 0.001) and knee flexion during stance (p = 0.001) compared to all other sessions. Step width was increased during BFR sessions (p = 0.001), but no difference in step length (p = 0.300) or cadence (p = 0.922) were observed. The time required to elicit change in anterior trunk flexion and plantar-flexion angle at toe-off was shorter during BFR sessions (p = 0.024). The BFR sessions elicited the highest ratings of perceived exertion and discomfort, as well as blood lactate concentration (p ≤ 0.001). Application of BFR during moderate and fast treadmill walking modifies gait kinematics and exacerbates exercise-related sensations as well as blood lactate concentration.

Applying blood flow restriction changes walking kinematics, causing an overall increase in anterior trunk flexion and knee flexion during stance while simultaneously reducing plantar-flexion angle at toe-off and ankle joint velocity.Applying blood flow restriction exacerbate exercise-related sensations of exertion and discomfort.Sample site does not influence the level of post-exercise blood lactate or markers of cell-membrane potential and damage.

Do Sideline Tests of Vestibular and Oculomotor Function Accurately Diagnose Sports-Related Concussion in Adults? A Systematic Review and Meta-analysis.

BACKGROUND: Sports-related concussion (SRC) assessment tools are primarily based on subjective assessments of somatic, cognitive, and psychosocial/emotional symptoms. SRC symptoms remain underreported, and objective measures of SRC impairments would be valuable to assist diagnosis. Measurable impairments to vestibular and oculomotor processing have been shown to occur after SRC and may provide valid objective assessments. PURPOSE: Determine the diagnostic accuracy of sideline tests of vestibular and oculomotor dysfunction to identify SRC in adults. STUDY DESIGN: Systematic review; Level of evidence, 4. METHODS: Electronic databases and gray literature were searched from inception until February 12, 2020. Physically active individuals (>16 years of age) who participated in sports were included. The reference standard for SRC was a combination of clinical signs and symptoms (eg, the Sport Concussion Assessment Tool [SCAT]), and index tests included any oculomotor assessment tool. The QUADAS tool was used to assess risk of bias, with the credibility of the evidence being rated according to GRADE. RESULTS: A total of 8 studies were included in this review. All included studies used the King-Devick test, with no other measures being identified. Meta-analysis was performed on 4 studies with a summary sensitivity and specificity of 0.77 and 0.82, respectively. The overall credibility of the evidence was rated as very low. CONCLUSION: Caution must be taken when interpreting these results given the very low credibility of the evidence, and the true summary sensitivity and specificity may substantially differ from the values calculated within this systematic review. Therefore, we recommend that clinicians using the King-Devick test to diagnose SRC in adults do so in conjunction with other tools such as the SCAT. PROSPERO REGISTRATION: CRD42018106632.

Modifying bowling kinematics in cricket pace bowlers with exercise-based injury prevention: A cluster-randomised controlled trial.

OBJECTIVES: Undesirable bowling kinematics can increase the risk of low back injury. This study investigated if an exercise-based injury prevention program (IPP) could modify bowling kinematics in community-level adolescent pace bowlers. DESIGN: Cluster-randomised controlled trial. METHODS: Pace bowlers from eight cricket organisations were cluster-randomised into an intervention or control group. At baseline and follow-up sessions biomechanical bowling data were collected. Between sessions, the intervention group completed an eight-week IPP while the control continued their normal cricket activity. Treatment effects (95% CI) were estimated with linear mixed models. RESULTS: There were significant treatment effects favouring the intervention group for shoulder counter-rotation (-3.8°; -7.2° to -0.3°) and lateral trunk flexion relative to the pelvis (-2.2°; -4.0° to -0.5°). Shoulder counter-rotation also increased in the control group by 2.2° (Cohen's d=0.22). There were no effects of the intervention on: lateral trunk flexion at front foot contact (FFC) (1.2°; -2.5° to 4.8°), lateral trunk flexion at ball release (BR) (-0.5°; -3.0° to 2.0°), pelvis rotation at FFC (0.9°; -4.0° to 2.2°), pelvis rotation at BR (-1.1°; -5.7° to 3.6°), front hip angle at FFC (1.6°; -3.6° to 6.7°), front hip angle at BR (-1.6°; -5.0° to 1.9°), front knee angle at FFC (-1.1°; -4.5° to 2.3°), front knee angle at BR (1.7°; -5.6° to 9.1°), or ball velocity (1.1kmh-1; -7.5kmh-1 to 9.7kmh-1). CONCLUSIONS: The IPP maintained shoulder counter-rotation and lateral trunk flexion relative to the pelvis in the intervention group and this could attenuate injury risk. No treatment effects were observed for lower-limb kinematics.

Sessional work-rate does not affect the magnitude to which simulated hypoxia can augment acute physiological responses during resistance exercise.

PURPOSE: To investigate whether performing resistance exercise in hypoxia augments physiological and perceptual responses, and if altering work-rate by performing repetitions to failure compared to sub-maximally increases the magnitude of these responses. METHODS: Twenty male university students (minimum of 2 year resistance training experience) completed four sessions, two in hypoxia (fraction of inspired oxygen [FiO2] = 0.13), and two in normoxia (FiO2 = 0.21). For each condition, session one comprised three sets to failure of shoulder press and bench press (high work-rate session), while session two involved the same volume load, distributed over six sets (low work-rate session). Muscle oxygenation (triceps brachii), surface electromyographic activity (anterior deltoid, pectoralis major, and triceps brachii), heart rate (HR), and arterial blood oxygen saturation were recorded. Blood lactate concentration ([Bla-]) was recorded pre-exercise and 2 min after each exercise. Muscle thickness was measured pre- and post-exercise via ultrasound. RESULTS: Muscle oxygenation values during sets and inter-set rest periods were lower in hypoxia vs normoxia (p = 0.001). Hypoxia caused greater [Bla-] during the shoulder press of failure sessions (p = 0.003) and both shoulder press (p = 0.048) and bench press (p = 0.005) of non-failure sessions. Hypoxia increased HR during non-failure sessions (p < 0.001). There was no effect of hypoxia on muscular swelling, surface electromyographic activity, perceived exertion, or number of repetitions performed. CONCLUSIONS: Hypoxia augmented metabolite accumulation, but had no impact on any other physiological or perceptual response compared to the equivalent exercise in normoxia. Furthermore, the magnitude to which hypoxia increased the measured physiological responses was not influenced by sessional work-rate.

Exercise-based injury prevention for community-level adolescent cricket pace bowlers: A cluster-randomised controlled trial.

OBJECTIVES: To investigate if an exercise-based injury prevention program (IPP) can modify risk factors for injury in community-level adolescent cricket pace bowlers. DESIGN: Cluster-randomised controlled trial. METHODS: Eight cricket organisations (training two times per week and no previous involvement in a structured IPP) participated in this cluster-randomised trial. Participants were aged 14-17 years, injury free, and not currently performing a rehabilitation/exercise program. Cricket organisations (clusters) were block-randomised by computerised number generation into an intervention group (performed an eight-week IPP at training) or control group (continued their usual cricket activity). Participants were not blinded to group allocation. Strength, endurance, and neuromuscular control were assessed at baseline and follow-up. Treatment effects were estimated using linear mixed models. RESULTS: Sixty-five male adolescent pace bowlers (intervention n=32 and control n=33) were randomised. There were significant treatment effects favouring the intervention group for shoulder strength (90°/s) 0.05 (95% CI 0.02-0.09) Nm/kg, hamstring strength (60°/s) 0.32 (95% CI 0.13-0.50) Nm/kg, hip adductor strength dominant 0.40 (95% CI 0.26-0.55) Nm/kg and non-dominant 0.33 (95% CI 0.20-0.47) Nm/kg, SEBT reach distance dominant 3.80 (95% CI 1.63-6.04) percent of leg length (%LL) and non-dominant 3.60 (95% CI 1.43-5.78) %LL, and back endurance 20.4 (95% CI 4.80-36.0) seconds. No differences were observed for shoulder strength (180°/s) (p=0.09), hamstring strength (180°/s) (p=0.07), lumbopelvic stability (p=0.90), and single leg squat knee valgus angle (dominant p=0.06, non-dominant p=0.15). CONCLUSIONS: Exercise-based IPPs can modify risk factors for injury in community-level adolescent pace bowlers. Future research is needed to confirm if IPPs can also reduce injury risk in this population.

Predictors of clinical success with stabilization exercise are associated with lower levels of lumbar multifidus intramuscular adipose tissue in patients with low back pain.

Purpose: Investigate the construct validity of prognostic factors purported to predict clinical success with stabilization exercise for low back pain by exploring their associations with lumbar multifidus composition.Methods: Patients with low back pain were recruited from a hospital imaging department. The presence of fivepredictors (age <40 years, positive prone instability test, aberrant trunk flexion movements, straight leg raise range of motion >91°, spinal hypermobility) were identified by standardized physical examination. Predictors were grouped by total positive findings and status on a clinical prediction rule. The proportion of lower lumbar multifidus intramuscular adipose tissue was measured with 3.0 T magnetic resonance imaging. Univariate and multivariate associations were examined with linear regression and reported with standardized beta coefficients (ß) and 95% confidence intervals.Results: Data from 62 patients (11 female) with mean (SD) age of 45.2 (11.8) years were included. Total number of predictors (ß[95% CI] = -0.37[-0.61,-0.12]; R2 = 0.12), positive prediction rule status (ß[95% CI] = -0.57[-0.79,-0.35]; R2 = 0.30), and age <40 years were associated with lower intramuscular adipose tissue (ß[95% CI] = -0.55[-0.77,-0.33]; R2 = 0.27). No other individual factors were associated with lumbar multifidus intramuscular adipose tissue.Conclusions: These findings support the construct validity of the grouped prognostic criteria. Future research should examine the clinical utility of these criteria. Implications for RehabilitationLow back pain is the single largest cause of disability worldwide and exercise therapy is recommended by international low back pain treatment guidelines.Lower levels of lumbar multifidus intramuscular adipose tissue were associated with predictors of clinical success with stabilization exercise.Higher proportions of lumbar multifidus intramuscular adipose tissue may help identify patients who require longer duration exercise training, or those who are unlikely to respond to stabilization exercise.

Using a Load-Velocity Relationship to Predict One repetition maximum in Free-Weight Exercise: A Comparison of the Different Methods.

Hughes, LJ, Banyard, HG, Dempsey, AR, and Scott, BR. Using a load-velocity relationship to predict one repetition maximum in free-weight exercise: a comparison of the different methods. J Strength Cond Res 33(9): 2409-2419, 2019-The purpose of this study was to investigate the reliability and validity of predicting 1 repetition maximum (1RM) in trained individuals using a load-velocity relationship. Twenty strength-trained men (age: 24.3 ± 2.9 years, height: 180.1 ± 5.9 cm, and body mass: 84.2 ± 10.5 kg) were recruited and visited the laboratory on 3 occasions. The load-velocity relationship was developed using the mean concentric velocity of repetitions performed at loads between 20 and 90% 1RM. Predicted 1RM was calculated using 3 different methods discussed in existing research: minimal velocity threshold 1RM (1RMMVT), load at zero velocity 1RM (1RMLD0), and force-velocity 1RM methods (1RMFV). The reliability of 1RM predictions was examined using intraclass correlation coefficient (ICC) and coefficient of variation (CV). 1RMMVT demonstrated the highest reliability (ICC = 0.92-0.96, CV = 3.6-5.0%), followed by 1RMLD0 (ICC = 0.78-0.82, CV = 8.2-8.6%) and 1RMFV (ICC = -0.28 to 0.00, CV = N/A). Both 1RMMVT and 1RMLD0 were very strongly correlated with measured 1RM (r = 0.91-0.95). The only method which was not significantly different to measured 1RM was the 1RMLD0 method. However, when analyzed on an individual basis (using Bland-Altman plots), all methods exhibited a high degree of variability. Overall, the results suggest that the 1RMMVT and 1RMLD0 predicted 1RM values could be used to monitor strength progress in trained individuals without the need for maximal testing. However, given the significant differences between 1RMMVT and measured 1RM, and the high variability associated with individual predictions performed using each method, they cannot be used interchangeably; therefore, it is recommended that predicted 1RM is not used to prescribe training loads as has been previously suggested.

Kinetic Gait Analysis of Agility Dogs Entering the A-Frame.

OBJECTIVE: The main purpose of this study was to investigate the effect of a decrease in the A-frame angle of incline on the vertical and cranio-caudal ground reaction forces observed in a homogeneous cohort of agility dogs during entrance and contact with the A-frame. MATERIALS AND METHODS: A crossover study design was applied to eight large breed dogs to compare the vertical and cranio-caudal ground reaction forces entering the A-frame at three angles of incline: 40° (standard), 35° and 30°. The peak vertical force, passive impact peak, peak propulsive force, peak braking force, the time point (percentile) in the stance phase at which these events occurred and the proportion of time for limb contact spent in braking (% braking) and propulsion (% propulsion) were examined.The variables measured from three trials at each incline were evaluated for a significant effect of A-frame angle with height and velocity included as covariates. RESULTS: The peak propulsive force and the % propulsion were significantly higher at the 40° angle of incline compared with 30° (p = 0.013, p = 0.0165 respectively) and the % braking was significantly lower at the 40° angle of incline compared with 30° (p = 0.0165). There was no significant effect of A-frame angle on the vertical ground reaction forces measured. CLINICAL SIGNIFICANCE: Compared with 30° incline, ascent up the A-frame at a 40° incline requires a higher propulsive force and extended time in propulsion to maintain forward movement and convert potential energy into forward kinetic energy.

Using Load-Velocity Relationships to Quantify Training-Induced Fatigue.

Hughes, LJ, Banyard, HG, Dempsey, AR, Peiffer, JJ, and Scott, BR. Using load-velocity relationships to quantify training-induced fatigue. J Strength Cond Res 33(3): 762-773, 2019-The purpose of this study was to investigate using load-velocity relationships to quantify fluctuations in maximal strength (1 repetition maximum [1RM]), which occur as a result of training-induced fatigue. The 19 well-trained men (age: 24.3 ± 2.9 years, height: 180.1 ± 5.9 cm, body mass: 84.2 ± 10.5 kg, and squat 1RM: 151.1 ± 25.7 kg) who were recruited for this study attended 5 sessions. After baseline strength testing, individual load-velocity relationships were established using mean concentric velocity during visits 2, 4, and 5, with visit 3 consisting of a bout of fatiguing exercise (5 sets of squats performed to muscular failure with 70% 1RM). Predicted 1RM values were calculated using the minimal velocity threshold (1RMMVT), load at zero velocity (1RMLD0), and force-velocity (1RMFV) methods. Measured 1RM, maximal voluntary contractions, and perceived muscle soreness were used to examine the effects of fatigue in relation to the predicted 1RM scores. The 1RMMVT and 1RMLD0 demonstrated very strong and strong correlations with measured 1RM during each of the sessions (r = 0.90-0.96 and r = 0.77-0.84, respectively), while no strong significant correlations were observed for the 1RMFV. Further analysis using Bland-Altman plots demonstrated substantial interindividual variation associated with each method. These results suggest that load-velocity-based 1RM predictions are not accurate enough to be used for daily training load prescription, as has been previously suggested. Nevertheless, these predictions are practical to implement during an individual's warm-up and may be useful to indicate general fluctuations in performance potential, particularly if used in conjunction with other common monitoring methods.

Injury Prevention Strategies for Adolescent Cricket Pace Bowlers.

Adolescent cricket pace bowlers are prone to non-contact shoulder, low back and lower-limb injuries. Exercise-based injury prevention programmes (IPPs) are effective for reducing non-contact injuries in athletes; however, a specific programme for adolescent pace bowlers has not been published. This paper therefore seeks to provide a rationale for the development of an exercise-based IPP specific for adolescent pace bowlers. It also outlines design principles and provides an example exercise programme that can be implemented at the community level. In addition, the paper addresses other injury prevention techniques concerned with the prescription of appropriate bowling loads and the modification of poor bowling biomechanics. Performing an exercise-based IPP before cricket training could reduce injury rates in adolescent pace bowlers. Eccentric strengthening exercises can be employed to target injuries to the posterior shoulder muscles, hip adductors and hamstring muscles. The risk of low back, knee and ankle injury could also be reduced with the inclusion of dynamic neuromuscular control exercises and trunk extensor endurance exercises. Other prevention strategies that need to be considered include the modification of poor bowling biomechanics, such as shoulder counter-rotation and lateral trunk flexion. Coaches and players should also aim to quantify bowling load accurately and coaches should use this information to prescribe appropriate individualised bowling loads. Specifically, players would benefit from avoiding both long periods of low load and acute periods when load is excessively high. Future evidence is needed to determine the effectiveness of the example programme outlined in this paper. It would also be beneficial to investigate whether the modification of bowling biomechanics is achievable at the non-elite level and if bowling load can be accurately measured and manipulated within a community-level population.

The King-Devick test is a valid and reliable tool for assessing sport-related concussion in Australian football: A prospective cohort study.

OBJECTIVES: Sport-related concussion (SRC) research has focused on impaired oculomotor function. The King-Devick (K-D) test measures oculomotor performance and is reported to identify suboptimal brain function. The use of the K-D test in Australian football (AF), a sport involving body contact and tackling, has not been documented. Therefore, the objective of this study was to determine the test-retest reliability and diagnostic accuracy of the K-D test on a sub-elite AF team. DESIGN: Prospective cohort study METHODS: In total, 22 male players (19.6+2.3 years) were tested and re-tested on the K-D test. Those suspected of having a SRC secondary to a significant head impact were tested. Randomly selected additional players without SRC were assessed for comparison. RESULTS: There were observable learning effects between the first and second baseline testing (48 vs. 46s). The ICC for the first and second baseline tests was 0.91. Post-match test times were longer than the baseline times for players with SRC (n=7) (-1.9s; z=-5.08; p<0.0001). Players tested with no signs of SRC (n=13) had an improvement in time when compared with their baseline score (3.0s; z=-4.38; p<0.0001). The overall sensitivity was 0.98, specificity 0.96, and a kappa of κ=0.94. The positive likelihood ratio was 11.6 and the positive predictive value was 89.0%. CONCLUSIONS: This study supports the use of the K-D test due to its test-retest reliability, high sensitivity and specificity, and fast and simple use that is ideal for sports medicine professionals to make quick judgement on management and playability.

Reduction of the A-Frame Angle of Incline does not Change the Maximum Carpal Joint Extension Angle in Agility Dogs Entering the A-Frame.

OBJECTIVE: This article aims to investigate the effect of a decrease in the A-frame angle of incline on the highest carpal extension angle in agility dogs. METHODS: Kinematic gait analysis (two-dimensional) measuring carpal extension was performed on 40 dogs entering the A-frame at 3 angles of incline: 40° (standard), 35° and 30°. The highest carpal extension angle from three trials at each incline was examined for a significant effect of A-frame angle with height, body weight and velocity included as covariates. RESULTS: There was no significant effect of A-frame angle on the highest carpal joint extension angle for the first or second limb. The adjusted mean carpal extension angle for the first limb at 40° was 64° [95% confidence interval (CI), 60-68), at 35° was 61° (95% CI, 57-65) and at 30° was 62° (95% CI, 59-65). The raw mean carpal extension angle for all dogs across all A-frame angles for the first limb was 62° (95% CI, 60-64) and the second limb was 61° (95% CI, 59-63). CLINICAL SIGNIFICANCE: Decreasing the A-frame angle of incline from 40° to 30° did not result in reduced carpal extension angles. The failure to find a difference and the narrow CI of the carpal angles may indicate that the physiologic limits of carpal extension were reached at all A-frame angles.

Risk Factors for Non-Contact Injury in Adolescent Cricket Pace Bowlers: A Systematic Review.

BACKGROUND: Adolescent cricket pace bowlers are prone to injury. Recognising the risk factors for non-contact injury in this population will aid future injury prevention strategies. OBJECTIVE: To identify the risk factors for non-contact injury in adolescent cricket pace bowlers. METHODS: We systematically searched PubMed, Cochrane Library, PEDro, SPORTDiscus, Embase, and the South African Journal of Sports Medicine to identify all experimental and observational studies reporting risk factors for non-contact injuries in pace bowlers (aged 12-19 years). The search syntax included terms relevant to cricket bowling, injury, and known risk factors for injury. The Newcastle-Ottawa Quality Assessment Scale and a modified Newcastle-Ottawa Quality Assessment Scale were used to assess the risk of bias in the cohort and cross-sectional studies, respectively. RESULTS: Sixteen studies (five cross-sectional studies, 11 cohort studies) comprising 687 participants (96% male, 75% playing cricket in Australia) met the selection criteria and were included for qualitative synthesis. Three cross-sectional studies were rated as high risk of bias and two as very high risk of bias. For the cohort studies, three were rated as low risk of bias, and eight as high risk of bias. Injury was associated with bowling biomechanics (excessive lateral trunk flexion and pelvis/hip kinematics), reduced trunk endurance, poor lumbo-pelvic-hip movement control, and early signs of lumbar bone stress. Conflicting results were found by studies examining the mixed technique, bowling workload and quadratus lumborum asymmetry. CONCLUSIONS: The current systematic review identified a number bowling biomechanics and various neuromuscular deficiencies as risk factors for non-contact injury in adolescent pace bowlers. These factors may provide a useful target for future interventional research aiming to prevent injury in this population. Future studies should utilise prospective cohort designs, and ensure that participants are injury-free at baseline, confounding factors are well controlled and attrition rates are reported. REGISTRATION: This systematic review was registered a priori (PROSPERO, CRD42016043956).

Knee Biomechanics During Jogging After Arthroscopic Partial Meniscectomy: A Longitudinal Study.

BACKGROUND: Altered knee joint biomechanics is thought to play a role in the pathogenesis of knee osteoarthritis and has been reported in patients after arthroscopic partial meniscectomy (APM) while performing various activities. Longitudinally, understanding knee joint biomechanics during jogging may assist future studies to assess the implications of jogging on knee joint health in this population. PURPOSE: To investigate knee joint biomechanics during jogging in patients 3 months after APM and a healthy control group at baseline and 2 years later at follow-up. STUDY DESIGN: Controlled laboratory study. METHODS: Seventy-eight patients who underwent medial APM and 38 healthy controls underwent a 3-dimensional motion analysis during barefoot overground jogging at baseline. Sixty-four patients who underwent APM and 23 controls returned at follow-up. External peak moments (flexion and adduction) and the peak knee flexion angle during stance were evaluated for the APM leg, non-APM leg (nonoperated leg), and control leg. RESULTS: At baseline, the peak knee flexion angle was 1.4° lower in the APM leg compared with the non-APM leg ( P = .03). No differences were found between the moments in the APM leg compared with the control leg (all P > .05). However, the normalized peak knee adduction moment was 35% higher in the non-APM leg compared with the control leg ( P = .008). In the non-APM leg, the normalized peak knee adduction and flexion moments were higher compared with the APM leg by 16% and 10%, respectively, at baseline ( P ≤ .004). Despite the increase in the peak knee flexion moment in the APM leg compared with the non-APM leg ( P < .001), there were no differences in the peak knee flexion moment or any other parameter assessed at 2-year follow-up between the legs ( P > .05). CONCLUSION: Comparing the APM leg and control leg, no differences in knee joint biomechanics during jogging for the variables assessed were observed. Higher knee moments in the non-APM leg may have clinical implications for the noninvolved leg. Kinematic differences were small (~1.4°) and therefore of questionable clinical relevance. CLINICAL RELEVANCE: These results may facilitate future clinical research regarding the implications of jogging on knee joint health in middle-aged, overweight patients after APM.

Cartilage morphology at 2-3 years following anterior cruciate ligament reconstruction with or without concomitant meniscal pathology.

PURPOSE: To examine differences in cartilage morphology between young adults 2-3 years post-anterior cruciate ligament reconstruction (ACLR), with or without meniscal pathology, and control participants. METHODS: Knee MRI was performed on 130 participants aged 18-40 years (62 with isolated ACLR, 38 with combined ACLR and meniscal pathology, and 30 healthy controls). Cartilage defects, cartilage volume and bone marrow lesions (BMLs) were assessed from MRI using validated methods. RESULTS: Cartilage defects were more prevalent in the isolated ACLR (69 %) and combined group (84 %) than in controls (10 %, P < 0.001). Furthermore, the combined group showed higher prevalence of cartilage defects on medial femoral condyle (OR 4.7, 95 % CI 1.3-16.6) and patella (OR 7.8, 95 % CI 1.5-40.7) than the isolated ACLR group. Cartilage volume was lower in both ACLR groups compared with controls (medial tibia, lateral tibia and patella, P < 0.05), whilst prevalence of BMLs was higher on lateral tibia (P < 0.001), with no significant differences between the two ACLR groups for either measure. CONCLUSIONS: Cartilage morphology was worse in ACLR patients compared with healthy controls. ACLR patients with associated meniscal pathology have a higher prevalence of cartilage defects than ACLR patients without meniscal pathology. The findings suggest that concomitant meniscal pathology may lead to a greater risk of future OA than isolated ACLR. LEVEL OF EVIDENCE: III.

Comparing the Effectiveness of a Short-Term Vertical Jump vs. Weightlifting Program on Athletic Power Development.

Teo, SYM, Newton, MJ, Newton, RU, Dempsey, AR, and Fairchild, TJ. Comparing the effectiveness of a short-term vertical jump vs. weightlifting program on athletic power development. J Strength Cond Res 30(10): 2741-2748, 2016-Efficient training of neuromuscular power and the translation of this power to sport-specific tasks is a key objective in the preparation of athletes involved in team-based sports. The purpose of this study was to compare changes in center of mass (COM) neuromuscular power and performance of sport-specific tasks after short-term (6-week) training adopting either Olympic-style weightlifting (WL) exercises or vertical jump (VJ) exercises. Twenty-six recreationally active men (18-30 years; height: 178.7 ± 8.3 cm; mass: 78.6 ± 12.2 kg) were randomly allocated to either a WL or VJ training group and performance during the countermovement jump (CMJ), squat jump (SJ), depth jump (DJ), 20-m sprint, and the 5-0-5 agility test-assessed pre and posttraining. Despite the WL group demonstrating larger increases in peak power output during the CMJ (WL group: 10% increase, d = 0.701; VJ group: 5.78% increase, d = 0.328) and SJ (WL group: 12.73% increase, d = 0.854; VJ group: 7.27% increase, d = 0.382), no significant between-group differences were observed in any outcome measure studied. There was a significant main effect of time observed for the 3 VJs (CMJ, SJ, and DJ), 0- to 5-m and 0- to 20-m sprint times, and the 5-0-5 agility test time, which were all shown to improve after the training (all main effects of time p < 0.01). Irrespective of the training approach adopted by coaches or athletes, addition of either WL or VJ training for development of power can improve performance in tasks associated with team-based sports, even in athletes with limited preseason training periods.

Glucose Ingestion Does Not Improve Maximal Isokinetic Force.

The purpose of this study was to assess maximal isokinetic leg extension force in response to glucose ingestion and to determine whether any performance changes occur in a time-dependent manner. Seventeen young (22.1 ± 3.9 years), lean (%body fat [%BF]: 14.3 ± 8.0; %BF males: 9.7 ± 4.2; %BF females: 23.7 ± 4.2), and recreationally active (>150 min · wk(-1) of physical activity) male (n = 11) and female participants completed the trials. Using a double-blinded crossover design, participants performed sets of 3 maximum isokinetic efforts on a dynamometer (HumacNorm) before and after (5, 15, 30, 45, 60, 75, and 90 minutes after) ingesting either a carbohydrate (75 g glucose) or isovolumic placebo (saccharin-flavored) drink. Blood glucose and electromyography (EMG) were recorded concurrent with force output (max peak force; mean peak force). Despite a significant rise in blood glucose (mean glycemic excursion = 4.01 ± 1.18 mmol · L(-1)), there were no significant interactions in any (absolute or percentage) force (mean peak force: p ≥ 0.683; max peak force: p ≥ 0.567) or EMG (mean peak EMG: p ≥ 0.119; max peak EMG: p ≥ 0.247) parameters measured. The ingestion of glucose resulted in a 3.4% reduction in mean force across subsequent time points (highest: +2.1% at 15 minutes; lowest: -8.6% at 90 minutes after ingestion); however, this effect was small (d < 0.1). The ingestion of glucose does not alter performance of maximal isokinetic efforts in recreationally active young individuals. Additionally, there were no differences in force when assessed as a function of time after glucose ingestion. Consequently, in the absence of fatigue, carbohydrate ingestion is unlikely to present any ergogenic benefits to athletes performing resistance-based exercise.

Mechanisms underpinning the peak knee flexion moment increase over 2-years following arthroscopic partial meniscectomy.

BACKGROUND: Knee osteoarthritis is common in people who have undergone partial meniscectomy, and a higher external knee flexion moment during gait may be a potential contributor. Although the peak external knee flexion moment has been shown to increase from 3 months to 2 years following partial meniscectomy, mechanisms underpinning the increase in the peak knee flexion moment are unknown. METHODS: Sixty-six participants with partial meniscectomy completed three-dimensional gait (normal and fast pace) and quadriceps strength assessment at baseline (3 months following partial meniscectomy) and again 2 years later. Variables included external knee flexion moment, vertical ground reaction force, knee flexion kinematics, and quadriceps peak torque. FINDINGS: For normal pace walking, the main significant predictors of change in peak knee flexion moment were an increase in peak vertical ground reaction force (R(2)=0.55), mostly due to an increase in walking speed, and increase in peak knee flexion angle (R(2)=0.19). For fast pace walking, the main significant predictors of change in peak knee flexion moment were an in increase in peak vertical ground reaction force (R(2)=0.51) and increase in knee flexion angle at initial contact (R(2)=0.17). Change in peak vertical force was mostly due to an increase in walking speed. INTERPRETATION: Findings suggest that increases in vertical ground reaction force and peak knee flexion angle during stance are predominant contributors to the 2-year change in peak knee flexion moment. Future studies are necessary to refine our understanding of joint loading and its determinants following meniscectomy.