Functional knee brace use for 21 h leads to a longer duration to achieve peak vertical ground reaction forces and the removal of the brace after 17.5 h results in faster loading of the knee joint.

PURPOSE: To investigate the landing strategies used after discontinuing and continuing the use of a functional knee brace (FKB) while performing a drop jump. METHODS: Following published methodology and power analysis, 23 uninjured male athletes, mean age of 19.4 ± 3.0 years, performed seven tests, during three test conditions (nonbraced, braced and removed brace or continued brace use), over 6 days of 12 testing sessions (S) for a total of 38.5 h. Each subject was provided with a custom-fitted FKB. This study focuses on the single leg drop jump kinetics during S12 when subjects were randomly selected to remove the FKB after 17.5 h or continued use of FKB. The time to peak vertical ground reaction forces (PVGRF) and PVGRF were recorded on landing in eight trials. RESULTS: After brace removal, a significantly shorter mean time to PVGRF was recorded (9.4 ± 22.9 msec (3.9%), p = 0.005, 95% confidence interval (95% CI): -168.1, 36.1), while continued brace use required a nonsignificant (n.s.) longer mean duration to achieve PVGRF (19.4 ± 53.6 msec (8.9%), n.s., 95% CI: -49.7, 73.4). No significant mean PVGRF difference was found in brace removal (25.3 ± 65.8 N) and continued brace use (25.1 ± 23.0 N). CONCLUSION: Removal of FKB after 17.5 h of use led to a significantly shorter time to achieve PVGRF, while continued brace use for 21 h required a longer duration to achieve PVGRF, suggesting faster and slower knee joint loading, respectively. Understanding the concerns associated with the use of FKB and the kinetics of the knee joint will assist clinicians in counselling athletes about the risks and benefits of using an FKB. LEVEL OF EVIDENCE: Level II.

Monitoring the Prescribed and Experienced Heart Rate-Derived Training Loads in Elite Field Hockey Players.

Perrotta, AS, Taunton, JE, Koehle, MS, White, MD, and Warburton, DER. Monitoring the prescribed and experienced heart rate-derived training loads in elite field hockey players. J Strength Cond Res 33(5): 1394-1399, 2019-This study examined the congruence between the prescribed and experienced heart rate-derived training loads over a 5-week periodized mesocycle. Twenty-four elite female field hockey players training as part of a national team were monitored before an (FIH) Hockey World League tournament. Three on-field training sessions per week were prospectively designed focusing on technical, tactical, and physiologically oriented hockey drills. A training load value, modeling the periodized weekly loading scheme, was prescribed for each training session and was calculated using normative training load responses from performing on-field hockey drills. Magnitude-based inferences focusing on the effect size (ES) and a Pearson correlation coefficient (r) were used to examine the degree of difference and the strength of correlation between the prescribed and experienced training loads. A significant correlation was observed between the experienced and prescribed training loads over the 5-week mesocycle (r = 0.92, 90% confidence limit [CL] [0.84-0.96]). The percentage difference and the ES between the achieved and prescribed training loads were as follows: week 1 demonstrated a 2.0% difference (ES = 0.10, 90% CL [-0.22-0.41]), week 2 a -5.4% difference (ES = -0.41, 90% CL [-0.75 to -0.07]), week 3 a -1.5% difference (ES = -0.09, 90% CL [-0.37 to 0.20]), week 4 a 7.1% difference (ES = 0.46, 90% CL [0.14-0.78]), and week 5 a 3.5% difference (ES = 0.18, 90% CL [-0.17 to 0.53]). This investigation demonstrates the efficacy for coaches to prospectively design on-field training sessions using normative training load data to enhance the congruence between the prescribed and experienced training loads over a periodized mesocycle.

Kinematic Correlates of Kinetic Outcomes Associated With Running-Related Injury.

High magnitudes and rates of loading have been implicated in the etiology of running-related injuries. Knowledge of kinematic variables that are predictive of kinetic outcomes could inform clinic-based gait retraining programs. Healthy novice female runners ran on a treadmill while 3-dimensional biomechanical data were collected. Kinetic outcomes consisted of vertical impact transient, average vertical loading rate, instantaneous vertical loading rate, and peak braking force. Kinematic outcomes included step length), hip flexion angle at initial contact, horizontal distance from heel to center of mass at initial contact, shank angle at initial contact, and foot strike angle. Stepwise multiple linear regression was used to evaluate the amount of variance in kinetic outcomes explained by kinematic outcomes. A moderate amount of variance in kinetic outcomes (vertical impact transient = 46%, average vertical loading rate = 37%, instantaneous vertical loading rate = 49%, peak braking force = 54%) was explained by several discrete kinematic variables-predominantly speed, horizontal distance from heel to center of mass, foot strike angle, and step length. Hip flexion angle and shank angle did not contribute to any models. Decreasing step length and transitioning from a rearfoot strike may reduce kinetic risk factors for running-related injuries. In contrast, clinical strategies such as modifying shank angle and hip flexion angle would not appear to contribute significantly to the variance of kinetic outcomes after accounting for other variables.

Efficacy of Hot Yoga as a Heat Stress Technique for Enhancing Plasma Volume and Cardiovascular Performance in Elite Female Field Hockey Players.

Perrotta, AS, White, MD, Koehle, MS, Taunton, JE, and Warburton, DER. Efficacy of hot yoga as a heat stress technique for enhancing plasma volume and cardiovascular performance in elite female field hockey players. J Strength Cond Res 32(10): 2878-2887, 2018-This investigation examined the efficacy of hot yoga as an alternative heat stress technique for enhancing plasma volume percentage (PV%) and cardiovascular performance. Ten international caliber female field hockey players completed six 60-minute hot yoga sessions using permissive dehydration over 6 days, followed by a 6-day national team camp. Changes in PV% were examined throughout the intervention and postintervention period. A graded maximal exercise test was performed in a thermoneutral environment (23.2 ± 1.0° C) 24 hours before and 24 hours after intervention. Six days of hot yoga initiated a moderate state of hypovolemia (PV% = -3.5%, 90% confidence limit [CL] [-6.9 to -0.13]), trivial improvements in maximal aerobic power (V[Combining Dot Above]O2max) (effect size [ES] = 0.06, 90% CL [-0.16 to 0.28]), and run time to exhaustion (ES = 0.11, 90% CL [-0.07 to 0.29]). Small meaningful improvements were observed in running speed (km·h) at ventilatory threshold (VT1) (ES = 0.34, 90% CL [-0.08 to 0.76]), VT2 (ES = 0.53, 90% CL [-0.05 to 1.1]), along with adaptations in the respiratory exchange ratio during high-intensity exercise (ES = -0.25, 90% CL [-0.62 to 0.12]). A large plasma volume expansion transpired 72 hours after intervention (PV% = 5.0%, 90% CL [1.3-8.7]) that contracted to a small expansion after 6 days (PV% = 1.6%, 90% CL [-1.0 to 4.2]). This investigation provides practitioners an alternative heat stress technique conducive for team sport, involving minimal exercise stress that can preserve maximal cardiovascular performance over periodized rest weeks within the yearly training plan. Furthermore, improvements in submaximal performance and a delayed hypervolemic response may provide a performance-enhancing effect when entering a 6-day competition period.

Gait modifications to change lower extremity gait biomechanics in runners: a systematic review.

BACKGROUND: Abnormal biomechanics have been cited as a potential risk factor for running-related injury. Many modifiable biomechanical risk factors have also been proposed in the literature as interventions via gait retraining. AIM: To determine which interventions have successfully modified biomechanical variables linked to running-related injury. STUDY DESIGN: Systematic literature review. METHODS: MEDLINE, EMBASE, CINAHL, SportDiscus and PSYCINFO were searched using key terms related to running biomechanics and gait retraining. Quality of included studies was assessed using the modified Downs and Black Quality Index and a best evidence synthesis was performed. RESULTS: 27 studies investigating the effect of biomechanical interventions on kinetic, kinematic and spatiotemporal variables were included in this review. Foot strike manipulation had the greatest effect on kinematic measures (conflicting evidence for proximal joint angles; strong evidence for distal joint angles), real-time feedback had the greatest effect on kinetic measures (ranging from conflicting to strong evidence), and combined training protocols had the greatest effect on spatiotemporal measures (limited to moderate evidence). CONCLUSIONS: Overall, this systematic review shows that many biomechanical parameters can be altered by running modification training programmes. These interventions result in short term small to large effects on kinetic, kinematic and spatiotemporal outcomes during running. In general, runners tend to employ a distal strategy of gait modification unless given specific cues. The most effective strategy for reducing high-risk factors for running-related injury-such as impact loading-was through real-time feedback of kinetics and/or kinematics.

The effects of exercise in hypoxic and normoxic conditions on endothelin-1 and arterial compliance.

The purpose of this study was to determine the effects of short-term normoxic and hypoxic exercise on plasma endothelin-1 and nitric oxide levels, and the relationship of arterial compliance and pulmonary artery pressure to endothelin-1. Seven endurance-trained males completed two incremental and two steady-state exercise tests performed at ventilatory threshold in normoxia and hypoxia (fraction of inspired oxygen = 0.14). Plasma endothelin-1was measured throughout steady-state tests. Arterial compliance using applanation tonometry, plasma nitric oxide and pulmonary artery pressure using Doppler echocardiography were measured before and after exercise. Small arterial compliance and pulmonary artery pressure significantly increased following exercise. There were no main effects of condition or time for plasma endothelin-1and nitric oxide levels. There were no significant relationships between plasma endothelin-1 and arterial compliance or pulmonary artery pressure. In conclusion, mechanisms other than the endothelial system may play a role in the exercise-induced changes in small artery compliance in this study population. Moderate hypoxia and a 30-minute steady-state exercise have limited effects on plasma endothelin-1 in endurance-trained males.

Functional knee brace use effect on peak vertical ground reaction forces during drop jump landing.

PURPOSE: The aim of the study was to investigate the landing strategies used by non-injured athletes while wearing functional knee braces (FKB, BR condition) during a drop jump task compared with non-injured, non-braced (NBR condition) subjects and also to ascertain whether accommodation to a FKB was possible by non-injured BR subjects. METHODS: Twenty-three healthy male provincial and national basketball and field hockey athletes (age, 19.4 ± 3.0 years) were tested. Each subject was provided with a custom-fitted FKB. Five NBR testing sessions were performed over 3 days followed by five BR testing sessions also over 3 days, for a total of 17.5 h of testing per condition. Each subject performed eight trials of the drop jump task during each testing session per condition. Single-leg peak vertical ground reaction forces (PVGRF) and the time to PVGRF were recorded for each NBR and BR trail. RESULTS: The BR group mean PVGRF at landing was significantly lower (1,628 ± 405 N, 2.1 ± 0.5 BW versus 1,715 ± 403 N, 2.2 ± 0.5 BW, F (1,22) = 6.83, P = 0.01) compared with NBR subjects, respectively. The group mean time to PVGRF was not statistically longer during the BR condition (F (1,22) = 0.967, P = 0.3). Further, an accommodation trend was noted as percent performance difference decreased with continued FKB use. CONCLUSIONS: The significantly lower group mean PVGRF while using a FKB could keep traumatic forces from reaching the ACL until the active neuromuscular restraints are activated to provide protection to the knee joint ligaments. Also, accommodation to FKB is possible after approximately 14.0 h of brace use. The results of this paper will assist clinicians in providing information to their patients regarding a FKB ability to offer protection to an ACL-deficient knee or to address concerns about early muscle fatigue, energy expenditure, heart rate, and decrease in performance level. LEVEL OF EVIDENCE: Prospective study, Level I.

The effect of three different levels of footwear stability on pain outcomes in women runners: a randomised control trial.

BACKGROUND: The present study examines the injury status in women runners who are randomised to receive a neutral, stability or motion control running shoe. METHODS: 81 female runners were categorised into three different foot posture types (39 neutral, 30 pronated, 12 highly pronated) and randomly assigned a neutral, stability or motion control running shoe. Runners underwent baseline testing to record training history, as well as leg alignment, before commencing a 13-week half marathon training programme. Outcome measures included number of missed training days due to pain and three visual analogue scale (VAS) items for pain during rest, activities of daily living and with running. RESULTS: 194 missed training days were reported by 32% of the running population with the stability shoe reporting the fewest missed days (51) and the motion control shoe (79) the most. There was a significant main effect (p<0.001) for footwear condition in both the neutral and pronated foot types: the motion control shoe reporting greater levels of pain in all three VAS items. In neutral feet, the neutral shoe reported greater values of pain while running than the stability shoe; in pronated feet, the stability shoe reported greater values of pain while running than the neutral shoe. No significant effects were reported for the highly pronated foot, although this was limited by an inadequate sample size. CONCLUSION: The findings of this study suggest that our current approach of prescribing in-shoe pronation control systems on the basis of foot type is overly simplistic and potentially injurious.

Effect of functional knee brace use on acceleration, agility, leg power and speed performance in healthy athletes.

OBJECTIVES: To investigate performance levels and accommodation period to functional knee brace (FKB) use in non-injured braced subjects while completing acceleration, agility, lower extremity power and speed tasks. DESIGN: A 2 (non-braced and braced conditions) × 5 (testing sessions) repeated-measures design. METHODS: 27 healthy male athletes were provided a custom fitted FKB. Each subject performed acceleration, agility, leg power and speed tests over 6 days; five non-braced testing sessions over 3 days followed by five braced testing sessions also over 3 days. Each subject performed two testing sessions (3.5 h per session) each day. Performance levels for each test were recorded during each non-braced and braced trial. Repeated measures analysis of variance, with a post hoc Tukey's test for any test found to be significant, were used to determine if accommodation to FKB was possible in healthy braced subjects. RESULTS: Initial performance levels were lower for braced than non-braced for all tests (acceleration p=0.106; agility p=0.520; leg power p=0.001 and speed p=0.001). However, after using the FKB for approximately 14.0 h, no significant performance differences were noted between the two testing conditions (acceleration non-braced, 0.53±0.04 s; braced, 0.53±0.04 s, p=0.163, agility non-braced, 9.80±0.74 s; braced, 9.80±0.85 s, p=0.151, lower extremity power non-braced, 58±7.4 cm; braced, 57±8.1 cm, p=0.163 and speed non-braced, 1.86±0.11 s; braced, 1.89±0.11 s, p=0.460). CONCLUSIONS: An initial decrement in performance levels was recorded when a FKB is used during an alactic performance task. After 12.0-14.0 h of FKB use, performance measures were similar between the two testing conditions.

A prospective study of physician-observed concussions during junior ice hockey: implications for incidence rates.

OBJECT: The objective of this study was to measure the incidence of concussion (scaled relative to number of athlete exposures) and recurrent concussion within 2 teams of fourth-tier junior ice hockey players (16-21 years old) during 1 regular season. METHODS: A prospective cohort study called the Hockey Concussion Education Project was conducted during 1 junior ice hockey regular season (2009-2010) involving 67 male fourth-tier ice hockey players (mean age 18.2 ± 1.2 years, range 16-21 years) from 2 teams. Prior to the start of the season, every player underwent baseline assessments using the Sideline Concussion Assessment Tool 2 (SCAT2) and the Immediate Post-Concussion Assessment and Cognitive Test (ImPACT). The study protocol also required players who entered the study during the season to complete baseline SCAT2 and ImPACT testing. If the protocol was not followed, the postinjury test results of a player without true baseline test results would be compared against previously established age and gender group normative levels. Each regular season game was observed by a qualified physician and at least 1 other neutral nonphysician observer. Players who suffered a suspected concussion were evaluated at the game. If a concussion diagnosis was made, the player was subsequently examined in the physician's office for a full clinical evaluation and the SCAT2 and ImPACT were repeated. Based on these evaluations, players were counseled on the decision of when to return to play. Athlete exposure was defined as 1 game played by 1 athlete. RESULTS: Twenty-one concussions occurred during the 52 physician-observed games (incidence 21.5 concussions per 1000 athlete exposures). Five players experienced repeat concussions. No concussions were reported during practice sessions. A concussion was diagnosed by the physician in 19 (36.5%) of the 52 observed games. One of the 5 individuals who suffered a repeat concussion sustained his initial concussion in a regular season game that was not observed by a physician, and as a result this single case was not included in the total of 21 total concussions. This initial concussion of the player was identified during baseline testing 2 days after the injury and was subsequently medically diagnosed and treated. CONCLUSIONS: The incidence of game-related concussions (per 100 [corrected] athlete exposures) in these fourth-tier junior [corrected] ice hockey players was 7 [corrected] times higher than [corrected] previously reported in the literature. This difference may be the result of the use of standardized direct physician observation, diagnosis, and subsequent treatment. The results of this study demonstrate the need for follow-up studies involving larger and more diverse sample groups to reflect generalizability of the findings. These follow-up studies should involve other contact sports (for example football and rugby) and also include the full spectrum of gender, age, and skill levels.

A prospective study of concussion education in 2 junior ice hockey teams: implications for sports concussion education.

OBJECT: The aim of this study was to evaluate the effectiveness of an educational intervention on concussion knowledge within a sample of junior fourth-tier ice hockey players. METHODS: A prospective cohort study, called the Hockey Concussion Education Project, was conducted during 1 junior ice hockey regular season (2009-2010) with 67 male fourth-tier ice hockey players (mean age 18.2 ± 1.2 years, range 16-21 years) from 2 teams. All participating players were randomized into 3 concussion education intervention groups (DVD group, interactive computer module [ICM] group, or control group) before the beginning of the season. Each individual received a preintervention knowledge test prior to the intervention. The DVD and ICM groups received a posttest after the completion of their intervention. All participants were offered the same knowledge test at 15 games (50 days) and 30 games (91 days) later. RESULTS: In the concussion education intervention component no significant group differences were observed at baseline between individuals in the control group and between individuals within the interventional group. At the 15-game follow-up, however, the difference between groups approached significance (F [1, 30] = 3.91, p = 0.057). This group difference remained consistent at the 30-game follow-up. CONCLUSIONS: This study demonstrates a positive trend concerning concussion education intervention and knowledge acquisition with either the ICMs or the educational DVD. Both forms of intervention produced a positive and sustainable improvement that approached statistical significance when compared with the control group. The control group demonstrated a negative longitudinal trend concerning concussion knowledge.

Return to play after an initial or recurrent concussion in a prospective study of physician-observed junior ice hockey concussions: implications for return to play after a concussion.

OBJECT: The authors investigated return-to-play duration for initial and recurrent concussion in the same season in 2 teams of junior (16-21-year-old) ice hockey players during a regular season. METHODS: The authors conducted a prospective cohort study during 1 junior regular season (2009-2010) of 67 male fourth-tier ice hockey players (mean age 18.2 ± 1.2 years [SD], range 16-21 years) from 2 teams. Prior to the start of the season, every player underwent baseline assessments that were determined using the Sideline Concussion Assessment Tool 2 (SCAT2) and the Immediate Post-Concussion Assessment and Cognitive Test (ImPACT). The study protocol also required players who entered the study during the season to complete a baseline SCAT2 and ImPACT. If the protocol was not followed, the postinjury test results of a player without true baseline test results were compared with previously established age- and sex-matched group normative levels. Each game was directly observed by a physician and at least 1 neutral nonphysician observer. Players suspected of suffering a concussion were evaluated by the physician during the game. If a concussion was diagnosed, the player underwent clinical evaluation at the physician's office within 24 hours. The return-to-play decision was based on clinical evaluation guided by the Zurich return-to-play protocol (contained in the consensus statement of international expert opinion at the 3rd International Conference on Concussion in Sport held in Zurich, November 2008). This clinical evaluation and return-to-play protocol was augmented by the 2 tests (SCAT2 and ImPACT) also recommended by the Zurich consensus statement, for which baseline values had been obtained. RESULTS: Seventeen players sustained a physician-observed or self-reported, physician-diagnosed concussion during a physician-observed ice hockey game. The mean clinical return-to-play duration (in 15 cases) was 12.8 ± 7.02 days (median 10 days, range 7-29 days); the mean number of physician office visits by players who suffered a concussion (15 cases) was 2.1 ± 1.29 (median 1.5 visits). Five of the 17 players who sustained a concussion also suffered a recurrent or second concussion. One of the 5 individuals who suffered a repeat concussion sustained his initial concussion in a regular season game that was not observed by a physician, and as a result this single case was not included in the total of 21 concussions. This initial concussion of the player was identified during baseline testing 2 days after the injury and was subsequently medically diagnosed and treated. The mean interval between the first and second concussions in these 5 players was 78.6 ± 39.8 days (median 82 days), and the mean time between the return-to-play date of the first and second concussions was 61.8 ± 39.7 days (median 60 days). CONCLUSIONS: The mean rates of return to play for single and recurrent concussions were higher than rates cited in recent studies involving sport concussions. The time interval between the first and second concussions was also greater than previously cited. This difference may be the result of the methodology of direct independent physician observation, diagnosis, and adherence to the Zurich return-to-play protocol.

Consecutive non-training days over a weekend for assessing cardiac parasympathetic variation in response to accumulated exercise stress.

Purpose: To examine the association between day-to-day resting cardiac parasympathetic variability over consecutive non-training days (i.e. weekend) and accumulated exercise stress when quantified using indices of cardiovascular strain. Methods: Twelve international calibre female field hockey players training as part of a national team were participants over a four-week mesocycle prior to a 2016 Olympic qualifying tournament. On-field exercise stress was examined using heart rate (HR) dynamics and quantified as; (1) training load and (2) time (min) spent above anaerobic threshold. The square root of the mean squared differences of successive cardiac cycles (R-R intervals) recorded on Saturday and Sunday were individually calculated and log-transformed prior to being averaged (Ln rMSSDweekend). Day-to-day variation in Ln rMSSD over the weekend was expressed using the coefficient of variation (Ln rMSSDCV). Non-linear regression analysis examined the association between accumulated exercise stress and Ln rMSSDCV. Results: A quadratic association between each index of exercise stress and Ln rMSSDCV was identified. After converting the coefficient of determination into a correlation coefficient (90% CL), the respective association between Ln rMSSDCV and training load (AU); r = 0.40 (0.16:0.59) and time above threshold; r = 0.35 (0.06:0.59) were observed. Conclusion: Ln rMSSDCV derived over consecutive non-training days displayed a moderate, yet significant association between accumulated exercise stress when expressed as global or high-intensity indices of cardiovascular strain. Weekend assessments may offer a practical and appropriate juncture between microcycles to assess the magnitude of perturbation in cardiac autonomic homeostasis prior to entering subsequent training periods.

The potential role of prophylactic/functional knee bracing in preventing knee ligament injury.

It is estimated that knee injuries account for up to 60% of all sport injuries, with the anterior cruciate ligament (ACL) accounting for almost half of these knee injuries. These knee injuries can result in high healthcare costs, as an ACL injury is often associated with surgery, long and costly rehabilitation, differing degrees of impairment and potential long-term consequences such as osteoarthritis. The interest in ACL injury prevention has been extensive for the past decade. Over this period, many ACL (intrinsic and extrinsic) injury risk factors have been identified and investigated by numerous researchers. Although prevention programmes have shown potential in decreasing knee ligament injuries, several researchers have suggested that no conclusive evidence has been presented in reducing the rate and/or severity of ACL injuries during sporting competition. Knee braces have been available for the last 30 years and have been used to assist individuals with ACL-deficient and ACL-reconstructed knees. However, research is limited on the use of knee braces (prophylactic and functional) to potentially prevent knee ligament injury in the non-injured population. One possible explanation for the limited research could be that the use of these devices has raised concerns of decreased or impaired athletic performance. In summary, the review of subjective and some objective publications suggests that a functional knee brace may offer stability to an ACL-deficient knee joint; however, research is limited on the use of a knee brace for prophylactic use in non-injured athletes. The limited research could be a result of fear of performance hindrance that has led to poor knee brace compliance.

Real-Time Biofeedback of Performance to Reduce Braking Forces Associated With Running-Related Injury: An Exploratory Study.

BACKGROUND: The high rate of running-related injury may be associated with increased peak braking forces (PBFs) and vertical loading rates. Gait retraining has been suggested by some experts to be an effective method to reduce loading parameters. OBJECTIVES: To investigate whether PBF could be decreased following an 8-session gait retraining program among a group of female recreational runners and which self-selected kinematic strategies could achieve this decrease. METHODS: In this exploratory study, 12 female recreational runners with high PBFs (greater than 0.27 body weight) completed an 8-session gait retraining program with real-time biofeedback of braking forces over the course of a half-marathon training program. Baseline and follow-up kinetics and kinematics were analyzed with a repeated-measures analysis of variance. RESULTS: There was an average reduction of 15% in PBF (-0.04 body weight; 95% confidence interval [CI]: -0.07, -0.02 body weight; P = .001; effect size, 0.62), accompanied by a 7% increase in step frequency (11.3 steps per minute; 95% CI: 1.8, 20.9 steps per minute; P = .024; effect size, 0.38) and a 6% decrease in step length (-5.5 cm; 95% CI: -9.9, -1.0 cm; P = .020; effect size, 0.40), from baseline to follow-up. CONCLUSION: The gait retraining program significantly reduced the PBF among a group of female recreational runners. This was achieved through a combination of increased step frequency and decreased step length. Furthermore, the modified gait pattern was incorporated into the runners' natural gait pattern by the completion of the program. Based on these results, the outlined gait retraining program should be further investigated to assess whether it may be an effective injury prevention strategy for recreational runners. This study was registered with ClinicalTrials.gov (NCT03302975). LEVEL OF EVIDENCE: Prevention, level 4. J Orthop Sports Phys Ther 2019;49(3):136-144. Epub 7 Dec 2018. doi:10.2519/jospt.2019.8587.

Cartilage recovery in runners with and without knee osteoarthritis: A pilot study.

OBJECTIVE: Running is an easy way of meeting physical activity recommendations for individuals with knee osteoarthritis (KOA); however, it remains unknown how their cartilage reacts to running. The objective of this pilot study was to compare the effects of 30 min of running on T2 and T1ρ relaxation times of tibiofemoral cartilage in female runners with and without KOA. METHODS: Ten female runners with symptomatic KOA (mean age 52.6 ±â€¯7.6 years) and 10 without KOA (mean age 52.5 ±â€¯7.8 years) ran for 30 min on a treadmill. Tibiofemoral cartilage T2 and T1ρ relaxation times were measured using magnetic resonance imaging prior to and immediately after the bout of running. Repeated-measures analyses of covariance (ANCOVA) were conducted to examine between-group differences across scanning times. RESULTS: No Group × Time interactions were found for T2 (P ≥ 0.076) or T1ρ (P ≥ 0.288) relaxation times. However, runners with KOA showed increased T2 values compared with pre-running in the medial and lateral femur 55 min post-running (5.4 to 5.5%, P < 0.022) and in all four tibiofemoral compartments 90 min post-running (6.9 to 11.1%, P < 0.01). A significant group effect was found for T1ρ in the medial femur, with greater values in those with KOA compared with controls. CONCLUSION: While Group × Time interactions in T2 and T1ρ relaxation times remained statistically insignificant, the observed significant increases in T2 in runners with tibiofemoral osteoarthritis TFOA may suggest slower and continuing changes in the cartilage and thus a need for longer recovery after running. Future research should investigate the effects of repeated exposure to running.

What are the perceptions about running and knee joint health among the public and healthcare practitioners in Canada?

OBJECTIVES: To evaluate the perceptions of the general public and healthcare practitioners (HCP) in Canada about the relationship between running and knee joint health, and to explore HCP`s usual recommendations to runners with knee osteoarthritis (KOA). METHODS: Non-runners and runners (with and without KOA) and HCP completed an online survey regarding the safety of running for knee joint health. HCP also provided information related to usual clinical recommendations. Proportions of agreement were compared between non-runners and runners. RESULTS: A total of 114 non-runners, 388 runners and 329 HCP completed the survey. Overall, running was perceived as detrimental for the knee joint by 13.1% of the general public, while 25.9% were uncertain. More uncertainty was reported regarding frequent (33.9%) and long-distance (43.6%) running. Statistical analyses revealed greater proportions of non-runners perceiving running negatively compared with runners. Overall, 48.4% believed that running in the presence of KOA would lead to disease progression, while 53.1% believed running would lead to premature arthroplasty. In HCP, 8.2%, 9.1% and 22.2% perceived that running in general, running frequently, or running long-distances are risk factors for KOA, respectively. 37.1% and 2.7% of HCP typically recommended patients with KOA to modify their running training or to quit running, respectively. CONCLUSION: High rates of uncertainty among the general public and HCP in Canada outline the need for further studies about running and knee joint health. Filling knowledge gaps will help inform knowledge translation strategies to better orientate the general public and HCP about the safety of running for knee joint health.

Sonographically guided intratendinous injection of hyperosmolar dextrose to treat chronic tendinosis of the Achilles tendon: a pilot study.

OBJECTIVE: Chronic tendinosis of the Achilles tendon is a common overuse injury that is difficult to manage. We report on a new injection treatment for this condition. SUBJECTS AND METHODS: Thirty-six consecutive patients (25 men, 11 women; mean age, 52.6 years) with symptoms for more than 3 months (mean, 28.6 months) underwent sonography-guided intratendinous injection of 25% hyperosmolar dextrose every 6 weeks until symptoms resolved or no improvement was shown. At baseline and before each injection, clinical assessment was performed using a visual analogue scale (VAS) for pain at rest (VAS1), pain during normal daily activity (VAS2), and pain during or after sporting or other physical activity (VAS3). Sonographic parameters including tendon thickness, echogenicity, and neovascularity were also recorded. Posttreatment clinical follow-up was performed via telephone interview. RESULTS: Thirty-three tendons in 32 patients were successfully treated. The mean number of treatment sessions was 4.0 (range, 2-11). There was a mean percentage reduction for VAS1 of 88.2% (p < 0.0001), for VAS2 of 84.0% (p < 0.0001), and for VAS3 of 78.1% (p < 0.0001). The mean tendon thickness decreased from 11.7 to 11.1 mm (p < 0.007). The number of tendons with anechoic clefts or foci was reduced by 78%. Echogenicity improved in six tendons (18%) but was unchanged in 27 tendons (82%). Neovascularity was unchanged in 11 tendons (33%) but decreased in 18 tendons (55%); no neovascularity was present before or after treatment in the four remaining tendons. Follow-up telephone interviews of the 30 available patients a mean of 12 months after treatment revealed that 20 patients were still asymptomatic, nine patients had only mild symptoms, and one patient had moderate symptoms. CONCLUSION: Intratendinous injections of hyperosmolar dextrose yielded a good clinical response--that is, a significant reduction in pain at rest and during tendon-loading activities--in patients with chronic tendinosis of the Achilles tendon.

The physiology of rock climbing.

In general, elite climbers have been characterised as small in stature, with low percentage body fat and body mass. Currently, there are mixed conclusions surrounding body mass and composition, potentially because of variable subject ability, method of assessment and calculation. Muscular strength and endurance in rock climbers have been primarily measured on the forearm, hand and fingers via dynamometry. When absolute hand strength was assessed, there was little difference between climbers and the general population. When expressed in relation to body mass, elite-level climbers scored significantly higher, highlighting the potential importance of low body mass. Rock climbing is characterised by repeated bouts of isometric contractions. Hand grip endurance has been measured by both repeated isometric contractions and sustained contractions, at a percentage of maximum voluntary contraction. Exercise times to fatigue during repeated isometric contractions have been found to be significantly better in climbers when compared with sedentary individuals. However, during sustained contractions until exhaustion, climbers did not differ from the normal population, emphasising the importance of the ability to perform repeated isometric forearm contractions without fatigue becoming detrimental to performance. A decrease in handgrip strength and endurance has been related to an increase in blood lactate, with lactate levels increasing with the angle of climbing. Active recovery has been shown to provide a better rate of recovery and allows the body to return to its pre-exercised state quicker. It could be suggested that an increased ability to tolerate and remove lactic acid during climbing may be beneficial. Because of increased demand placed upon the upper body during climbing of increased difficulty, possessing greater strength and endurance in the arms and shoulders could be advantageous. Flexibility has not been identified as a necessary determinant of climbing success, although climbing-specific flexibility could be valuable to climbing performance. As the difficulty of climbing increases, so does oxygen uptake (VO(2)), energy expenditure and heart rate per metre of climb, with a disproportionate rise in heart rate compared with VO(2). It was suggested that these may be due to a metaboreflex causing a sympathetically mediated pressor response. In addition, climbers had an attenuated blood pressure response to isometric handgrip exercises when compared with non-climbers, potentially because of reduced metabolite build-up causing less stimulation of the muscle metaboreflex. Training has been emphasised as an important component in climbing success, although there is little literature reviewing the influence of specific training components upon climbing performance. In summary, it appears that success in climbing is not related to individual physiological variables but is the result of a complex interaction of physiological and psychological factors.

Tarsal navicular stress injury: long-term outcome and clinicoradiological correlation using both computed tomography and magnetic resonance imaging.

BACKGROUND: Tarsal navicular stress fracture is a condition that has curtailed many athletic careers. Management protocols remain varied and somewhat controversial. HYPOTHESES: (1) Clinical practice does not mirror the recommendations reported from previous case series. (2) Clinical outcome is poor when navicular stress fracture is managed in a variety of ways. (3) Imaging does not correlate strongly with clinical status at long-term follow-up after navicular stress fracture. STUDY DESIGN: Case series (prognosis); Level of evidence, 4. METHODS: From a computer registry, we identified patients who had attended a university sports medicine center between 1996 and 2002 and whose final diagnosis was navicular stress fracture (n = 11) or navicular stress reaction (n = 9). All patients had provided demographic and clinical data at their original evaluation, and all had undergone bone scans and computed tomographic imaging. These data were extracted by chart review. Follow-up clinical and imaging assessments took place a median of 3.7 years later (range, 1-15.7 years). At these assessments, we administered a questionnaire, performed a structured physician examination (blinded to other data), scanned both feet with computed tomography, and obtained magnetic resonance images of the affected foot. RESULTS: Only 2 of 11 patients (18%) with navicular stress fractures received the literature-recommended treatment of at least 6 weeks' nonweightbearing cast immobilization. Of these 11 patients, only 6 (55%) returned to sports at their previous level. Only 3 patients with navicular stress fractures regained normal imaging appearance at follow-up. Pain score, stiffness, sporting success, current sporting involvement, and recurrence/time to recurrence were not statistically associated with computed tomographic or magnetic resonance imaging parameters. Of 9 patients with navicular stress reactions, 7 developed clinical and radiological features of navicular stress fracture, but 6 of 9 patients (67%) returned successfully to sports. CONCLUSIONS: Contemporary management of navicular stress fracture differs from that recommended in the literature. This stress fracture prevented almost half of the participants in this study from returning to sports at their previous level. Imaging parameters do not correlate with the clinical assessment of a patient at long-term follow-up of navicular stress fracture.