Context: High vertical ground reaction force (vGRF) when initiating ground contact during jump landing is one biomechanical factor that may increase risk of anterior cruciate ligament injury. Intervention programs have been developed to decrease vGRF to reduce injury risk, yet generating high forces is still critical for performing dynamic activities such as a vertical jump task. Objective: To evaluate if a jump-landing feedback intervention, cueing a decrease in vGRF, would impair vertical jump performance in a separate task (Vertmax). Design: Randomized controlled trial. Patients (or Other Participants): Forty-eight recreationally active females (feedback: n = 31; 19.63 [1.54] y, 1.6 [0.08] cm, 58.13 [7.84] kg and control: n = 15; 19.6 [1.68] y, 1.64 [0.05] cm, 60.11 [8.36] kg) participated in this study. Intervention: Peak vGRF during a jump landing and Vertmax were recorded at baseline and 4 weeks post. The feedback group participated in 12 sessions over the 4-week period consisting of feedback provided for 6 sets of 6 jumps off a 30-cm box. The control group was instructed to return to the lab 28 days following the baseline measurements. Main Outcome Measures: Change scores (postbaseline) were calculated for peak vGRF and Vertmax. Group differences were evaluated for peak vGRF and Vertmax using a Mann–Whitney U test (P < .05). Results: There were no significant differences between groups at baseline (P > .05). The feedback group (−0.5 [0.3] N/kg) demonstrated a greater decrease in vGRF compared with the control group (0.01 [0.3] N/kg) (t(46) = −5.52, P < .001). There were no significant differences in change in Vertmax between groups (feedback = 0.9 [2.2] cm, control = 0.06 [2.1] cm; t(46) = 0.46, P = .64). Conclusions: While the feedback intervention was effective in decreasing vGRF when landing from a jump, these participants did not demonstrate changes in vertical jump performance when assessed during a different task. Practitioners should consider implementing feedback intervention programs to reduce peak vGRF, without worry of diminished vertical jump performance.
Hayley M. Ericksen, Caitlin Lefevre, Brittney A. Luc-Harkey, Abbey C. Thomas, Phillip A. Gribble and Brian Pietrosimone
Pier Paolo Mariani, Luca Laudani, Jacopo E. Rocchi, Arrigo Giombini and Andrea Macaluso
Context: All rehabilitative programs before anterior cruciate ligament (ACL) reconstructive surgery, which are focused on recovery of proprioception and muscular strength, are defined as prehabilitation. While it has shown that prehabilitation positively affects the overall outcome after ACL reconstruction, it is still controversial whether preoperatively enhancing quadriceps strength has some beneficial effect on postoperative strength, mainly during the first period. Objective: To determine whether there is any relationship between preoperative and early postoperative quadriceps strength. Design: Case control. Setting: University research laboratory. Participants: Fifty-nine males (18–33 y; age: 23.69 [0.71] y) who underwent ACL reconstruction with patellar-tendon autograft were examined the day before surgery, and at 60 and 90 days after surgery. Main Outcome Measures: The limb symmetry index (LSI) was quantified for maximal voluntary isometric contraction of the knee extensor muscles and of the knee flexor muscles at 90° joint angle. A k-means analysis was performed on either quadriceps or hamstrings LSI before surgery to classify the patients in high and low preoperative LSI clusters. Differences in postoperative LSI were then evaluated between the high and low preoperative LSI clusters. Results: Following surgery, there were no differences in the quadriceps LSI between patients with high and low preoperative quadriceps LSI. Sixty days after surgery, the hamstrings LSI was higher in patients with high than low preoperative hamstrings LSI (84.0 [13.0]% vs 75.4 [15.9]%; P < .05). Conclusions: Findings suggest that quadriceps strength deficit is related to the ACL injury and increases further after the reconstruction without any correlation between the preoperative and postoperative values. Therefore, it appears that there is no need to delay surgery in order to increase the preoperative quadriceps strength before surgery.
Mhairi K. MacLean and Daniel P. Ferris
The authors tested 4 young healthy subjects walking with a powered knee exoskeleton to determine if it could reduce the metabolic cost of locomotion. Subjects walked with a backpack loaded and unloaded, on a treadmill with inclinations of 0° and 15°, and outdoors with varied natural terrain. Participants walked at a self-selected speed (average 1.0 m/s) for all conditions, except incline treadmill walking (average 0.5 m/s). The authors hypothesized that the knee exoskeleton would reduce the metabolic cost of walking uphill and with a load compared with walking without the exoskeleton. The knee exoskeleton reduced metabolic cost by 4.2% in the 15° incline with the backpack load. All other conditions had an increase in metabolic cost when using the knee exoskeleton compared with not using the exoskeleton. There was more variation in metabolic cost over the outdoor walking course with the knee exoskeleton than without it. Our findings indicate that powered assistance at the knee is more likely to decrease the metabolic cost of walking in uphill conditions and during loaded walking rather than in level conditions without a backpack load. Differences in positive mechanical work demand at the knee for varying conditions may explain the differences in metabolic benefit from the exoskeleton.
Mindi Fisher, Ryan Tierney, Anne Russ and Jamie Mansell
Clinical Question: In concussed patients, will having attention deficit hyperactivity disorder (ADHD) or learning difficulties (LD) versus not having ADHD or LD cause higher symptom severity scores or invalid baseline protocols? Clinical Bottom Line: Research supports the concept that there is a difference at baseline for individuals with ADHD and/or LD compared with those who do not.
Brittany M. Ingram, Melissa C. Kay, Christina B. Vander Vegt and Johna K. Register-Mihalik
Clinical Scenario: Current studies have identified body checking as the most common cause of sports-related concussion in ice hockey across all divisions and levels. As a result, many hockey organizations, particularly in youth sports, have implemented rules making body checking to the head, face, and/or neck illegal. Such a rule, in Canada, makes age 13 the first age in which individuals can engage in body checking. Despite these changes, effectiveness of their implementation on the incidence of concussion in Canadian male youth ice hockey players remains unclear. Clinical Question: What is the effect of body checking policy changes on concussion incidence in male youth ice hockey players? Summary of Key Findings: Of the 3 included studies, 2 studies reported a decrease in the incidence of concussion once a body checking policy change was implemented. The third study showed an increase; however, it is important to note that this may be due, in part, to increased awareness leading to better reporting of injuries. Clinical Bottom Line: Current evidence supports a relationship between body checking policy implementation and decreased concussion incidence; however, more research is needed to understand the long-term implications of policy change and the effects in other leagues. In addition, further data are needed to differentiate between increased concussion incidence resulting from concussion education efforts that may improve disclosure and increased concussion incidence as a direct result of policy changes. Strength of Recommendation: Grade B evidence exists that policy changes regarding body checking decrease concussion incidence in male youth ice hockey players.
Corey P. Ochs, Melissa C. Kay and Johna K. Register-Mihalik
Clinical Scenario: Collision sports are often at higher risk of concussion due to the physical nature and style of play. Typically, initial clinical recovery occurs within 7 to 10 days; however, even this time frame may result in significant time lost from play. Little has been done in previous research to analyze how individual game performance may be affected upon return to play postconcussion. Focused Clinical Question: Upon return-to-play clearance, how does sport-related concussion affect game performance of professional athletes in collision sports? Summary of Key Findings: All 3 studies included found no significant change in individual performance of professional collision-sport athletes upon returning to play from concussive injury. One of the studies indicated that there was no difference in performance for NFL athletes who did not miss a single game (returned within 7 d) and those who missed at least 1 game. One study indicated that although there was no change in performance of NFL players upon returning to play from sustained concussion, there was a decline in performance in the 2 weeks before the diagnosed injury and appearing on the injury report. The final study indicated that there was no difference in performance or style of play of NHL athletes who missed time due to concussive injury when compared with athletes who missed games for a noninjury factor. Clinical Bottom Line: There was no change in performance upon return from concussive injury suggesting that players appear to be acutely recovered from the respective concussion before returning to play. This suggests that current policies and management properly evaluate and treat concussed athletes of these professional sports. Strength of Recommendation: Grade C evidence exists that there is no change in individual game performance in professional collision-sport athletes before and after suffering a concussion.
Manuel Trinidad-Fernández, Manuel González-Sánchez and Antonio I. Cuesta-Vargas
Context: Several studies have shown that the kinematics of the scapula is altered in many disorders that affect the shoulder. Description of scapular motion in the chest continues to be a scientific and clinical challenge. Objective: To check the validity and reliability of a new, minimally invasive method of tracking the internal and external rotation of the scapula using ultrasound imaging combined with the signal provided by a 3-dimensional electromagnetic sensor. Design: A cross-sectional study with a repeated-measures descriptive test–retest design was employed to evaluate this new tracking method. The new method was validated in vitro and the reliability of data over repeated measures between scapula positions was calculated in vivo. Setting: University laboratory. Participants: A total of 30 healthy men and women. Main Outcome Measure: The validation of the scapula rotation tracking using the in vitro model was calculated by Pearson correlation test between a 2-dimensional cross-correlation algorithm of the new method and another software image. The reliability of the tracking of the scapula rotation was measured using the intraclass correlation coefficient. Results: In the validation in vitro, the correlation of rotations obtained by the 2 methods was good (r = .77, P = .01). The reliability in vivo had excellent results (intraclass correlation coefficient = .88; 95% confidence interval, .82–.93) in the test–retest analysis of 8 measures. The intrarater analysis of variance test showed no significant differences between the measures (P = .85, F = 0.46). Conclusion: Ultrasound imaging combined with a motion sensor to track the scapula has been shown to be a reliable and valid method for measuring internal and external rotation during separation of the upper limb.
Barıs Seven, Gamze Cobanoglu, Deran Oskay and Nevin Atalay-Guzel
Context: The evaluation of the wrist strength and proprioception gives clinicians and researchers information about effectiveness of their rehabilitation protocol or helps diagnosis of various neuromuscular and somatosensorial disorders. Isokinetic dynamometers are considered the gold standard for these evaluations. However, the studies about test–retest reliability of isokinetic dynamometer are inadequate. Objective: The purpose of this study was to determine the test–retest reliability of isokinetic wrist strength and proprioception measurements using the Cybex isokinetic dynamometer. Design: Test–retest reliability study. Setting: University laboratory. Participants: Thirty participants were enrolled (age 23.2 [2.8] y, height 171.1  cm, weight 66.6 [11.6] kg) in this study. Intervention: Cybex isokinetic dynamometer was used for strength and proprioception measurements. Main Outcome Measures: Concentric flexion–extension strength test was performed at 90°/s angular velocity, and eccentric flexion–extension strength test was performed at 60°/s angular velocity. The proprioception of the wrist was assessed via active joint position sense. The 30° extension of the wrist, which is accepted as the functional position of the wrist, was selected as the targeted angle. The intraclass correlation coefficient (ICC2,1) method was used for test–retest analysis (P < .05). Results: The active joint position sense measurements of dominant (ICC2,1: .821) and nondominant (ICC2,1: .763) sides were found to have good test–retest reliability. Furthermore, with the exception of dominant eccentric extension strength (moderate reliability) (ICC2,1: .733), eccentric and concentric flexion (dominant: ICC2,1 = .890–.844; nondominant: ICC2,1 = .800–.898, respectively), and extension (dominant: ICC2,1 = .791 [concentric], nondominant: ICC2,1 = .791–.818, respectively) strength measurements of both sides were found to have good reliability. Conclusions: This study shows that the Cybex isokinetic dynamometer is a reliable method for measuring wrist strength and proprioception. Isokinetic dynamometers can be used clinically for diagnosis or rehabilitation in studies which contain wrist proprioception or strength measurements.
Steven Nagib and Shelley W. Linens
Clinical Scenario: Every year, millions of people suffer a concussion. A significant portion of these people experience symptoms lasting longer than 10 days and are diagnosed with postconcussion syndrome. Dizziness is the second most reported symptom associated with a concussion and may be a predictor of prolonged recovery. Clinicians are beginning to incorporate vestibular rehabilitation therapy (VRT) in their postconcussion treatment plan, in order to address the dysfunctional inner ear structures that could be causing this dizziness. Focused Clinical Question: Can VRT help postconcussion syndrome patients experiencing prolonged dizziness by improving their perceived disability? Summary of Key Findings: Three studies were included: 1 randomized control trial, 1 retrospective chart review, and 1 exploratory study. The randomized control trial compared cervical spine therapy alone to cervical spine therapy in conjunction with VRT to obtain medical clearance for sport. The chart review explored VRT as a treatment for reducing dizziness and improving balance and gait dysfunction. The exploratory study implemented VRT in conjunction with light aerobic exercise to improve perceived disability associated with dizziness postconcussion. All 3 studies found statistically significant decreases (improvements) in Dizziness Handicap Index scores. Clinical Bottom Line: There is preliminary evidence suggesting that VRT can improve perceived disability in patients with postconcussion syndrome experiencing prolonged dizziness. There is a decrease (improvement) in Dizziness Handicap Index scores across all 3 studies. VRT is a relatively safe treatment option, with no adverse reactions or case reports. Strength of Recommendation: There is level 2 and level 3 evidence supporting the use of VRT to treat patients suffering from dizziness postconcussion.
Roel De Ridder, Julien Lebleu, Tine Willems, Cedric De Blaiser, Christine Detrembleur and Philip Roosen
Context: Wearable sensor devices have notable advantages, such as cost-effectiveness, easy to use, and real-time feedback. Wirelessness ensures full-body motion, which is required during movement in a challenging environment such as during sports. Research on the reliability and validity of commercially available systems, however, is indispensable. Objective: To confirm the test–retest reliability and concurrent validity of a commercially available body-worn sensor—BTS G-WALK® sensor system—for spatiotemporal gait parameters with the GAITRite® walkway system as golden standard. Design: Reliability and concurrent validity study. Setting: Laboratory setting. Participants: Thirty healthy subjects. Main Outcome Measures: Spatiotemporal parameters: speed, cadence, stride length, stride duration, stance duration, swing duration, double support, and single support. Results: In terms of test–retest reliability of the BTS G-WALK® sensor system, intraclass correlation coefficient values for both the spatial and temporal parameters were excellent between consecutive measurements on the same day with intraclass correlation coefficient values ranging from .85 to .99. In terms of validity, intraclass correlation coefficient values between measurement systems showed excellent levels of agreement for speed, cadence, stride length, and stride duration (range = .88–.97), and showed poor to moderate levels of agreement (range = .12–.47) for single/double support and swing/stance duration. Bland–Altman plots showed overall percentage bias values equal to or smaller than 3% with limits of agreement ≤15% (speed, cadence, stride length, stride duration, swing duration, and stance duration). Only for single and double support, the limits of agreement were higher with, respectively, −15.4% to 19.5% and −48.0% to 51.4%. Conclusion: The BTS G-WALK® sensor system is reliable for all measured spatiotemporal parameters. In terms of validity, excellent concurrent validity was shown for speed, cadence, stride length, and stride duration. Cautious interpretation is necessary for temporal parameters based on final foot contact (stance, swing, and single/double support time).