Objective: To examine the selective influences of distinct acceleration profiles on the neuromuscular efficiency, force, and power during concentric and eccentric phases of isoinertial squatting exercise. Design: Cross-sectional study. Setting: Biomechanics laboratory of the university. Participants: A total of 38 active adults were divided according to their acceleration profiles: higher (n = 17; >2.5 m/s2) and lower acceleration group (n = 21; <2.5 m/s2). Intervention: All subjects performed squats until failure attached to an isoinertial conic pulley device monitored by surface electromyography of rectus femoris, vastus medialis, vastus lateralis, biceps femoris, and semitendinosus. Main Outcome Measures: An incremental optical encoder was used to assess maximal and mean power and force during concentric and eccentric phases. The neuromuscular efficiency was calculated using the mean force and the electromyographic linear envelope. Results: Between-group differences were observed for the maximal and mean force (P range = .001–.005), power (P = .001), and neuromuscular efficiency (P range = .001–.03) with higher significant values for the higher acceleration group in both concentric and eccentric phases. Conclusion: Distinct acceleration profiles affect the neuromuscular efficiency, force, and power during concentric and eccentric phases of isoinertial squatting exercise. To ensure immediate higher levels of power and force output without depriving the neuromuscular system, acceleration profiles higher than 2.5 m/s2 are preferable. The acceleration profiles could be an alternative to evolve the isoinertial exercise.
Denys Batista Campos, Isabella Christina Ferreira, Matheus Almeida Souza, Macquiden Amorim Jr, Leonardo Intelangelo, Gabriela Silveira-Nunes, and Alexandre Carvalho Barbosa
Kyung-eun Lee, Seung-min Baik, Chung-hwi Yi, Oh-yun Kwon, and Heon-seock Cynn
Context: Side bridge exercises strengthen the hip, trunk, and abdominal muscles and challenge the trunk muscles without the high lumbar compression associated with trunk extension or curls. Previous research using electromyography (EMG) reports that performance of the side bridge exercise highly activates the gluteus medius (Gmed). However, to the best of our knowledge, no previous research has investigated EMG amplitude in the hip and trunk muscles during side bridge exercise in subjects with Gmed weakness. Objective: The purpose of this study was to examine the EMG activity of the hip and trunk muscles during 3 variations of the side bridge exercise (side bridge, side bridge with knee flexion, and side bridge with knee flexion and hip abduction of the top leg) in subjects with Gmed weakness. Design: Repeated-measures experimental design. Setting: Research laboratory. Patients: Thirty subjects (15 females and 15 males) with Gmed weakness participated in this study. Intervention: Each subject performed 3 variations of the side bridge exercise in random order. Main Outcome Measures: Surface EMG was used to measure the muscle activities of the rectus abdominis, external oblique, longissimus thoracis, multifidus, Gmed, gluteus maximus, and tensor fasciae latae (TFL), and Gmed/TFL muscle activity ratio during 3 variations of the side bridge exercise. Results: There were significant differences in Gmed (F2,56 = 110.054, P < .001), gluteus maximus (F2,56 = 36.416, P < .001), and TFL (F2,56 = 108.342, P < .001) muscles among the 3 side bridge exercises. There were significant differences in the Gmed/TFL muscle ratio (F2,56 = 20.738, P < .001). Conclusion: Among 3 side bridge exercises, the side bridge with knee flexion may be effective for the individuals with Gmed weakness among 3 side bridge exercises to strengthen the gluteal muscles, considering the difficulty of the exercise and relative contribution of Gmed and TFL.
Bruno Augusto Lima Coelho, Helena Larissa das Neves Rodrigues, Gabriel Peixoto Leão Almeida, and Sílvia Maria Amado João
Context: Restriction in ankle dorsiflexion range of motion (ROM) has been previously associated with excessive dynamic knee valgus. This, in turn, has been correlated with knee pain in women with patellofemoral pain. Objectives: To investigate the immediate effect of 3 ankle mobilization techniques on dorsiflexion ROM, dynamic knee valgus, knee pain, and patient perceptions of improvement in women with patellofemoral pain and ankle dorsiflexion restriction. Design: Randomized controlled trial with 3 arms. Setting: Biomechanics laboratory. Participants: A total of 117 women with patellofemoral pain who display ankle dorsiflexion restriction were divided into 3 groups: ankle mobilization with anterior tibia glide (n = 39), ankle mobilization with posterior tibia glide (n = 39), and ankle mobilization with anterior and posterior tibia glide (n = 39). Intervention(s): The participants received a single session of ankle mobilization with movement technique. Main Outcome Measures: Dorsiflexion ROM (weight-bearing lunge test), dynamic knee valgus (frontal plane projection angle), knee pain (numeric pain rating scale), and patient perceptions of improvement (global perceived effect scale). The outcome measures were collected at the baseline, immediate postintervention (immediate reassessment), and 48 hours postintervention (48 h reassessment). Results: There were no significant differences between the 3 treatment groups regarding dorsiflexion ROM and patient perceptions of improvement. Compared with mobilization with anterior and posterior tibia glide, mobilization with anterior tibia glide promoted greater increase in dynamic knee valgus (P = .02) and greater knee pain reduction (P = .02) at immediate reassessment. Also compared with mobilization with anterior and posterior tibia glide, mobilization with posterior tibia glide promoted greater knee pain reduction (P < .01) at immediate reassessment. Conclusion: In our sample, the direction of the tibia glide in ankle mobilization accounted for significant changes only in dynamic knee valgus and knee pain in the immediate reassessment.
Arthur Alves Dos Santos, James Sorce, Alexandra Schonning, and Grant Bevill
This study evaluated the performance of 6 commercially available hard hat designs—differentiated by shell design, number of suspension points, and suspension tightening system—in regard to their ability to attenuate accelerations during vertical impacts to the head. Tests were conducted with impactor materials of steel, wood, and lead shot (resembling commonly seen materials in a construction site), weighing 1.8 and 3.6 kg and dropped from 1.83 m onto a Hybrid III head/neck assembly. All hard hats appreciably reduced head acceleration to the unprotected condition. However, neither the addition of extra suspension points nor variations in suspension tightening mechanism appreciably influenced performance. Therefore, these results indicate that additional features available in current hard hat designs do not improve protective capacity as related to head acceleration metrics.
Nicole Sordello, Tenli Bright, Taylor Truesdell, Jace Puckett, Jayme G. Baker, and Russell T. Baker
Focused Clinical Question: What are the effects of Total Motion Release® on shoulder range of motion compared with stretching in overhead athletes? Clinical Bottom Line: Total Motion Release® significantly improved acute dominant and nondominant shoulder ROM compared with dynamic warm-up and stretching protocols. The application of Total Motion Release® was also found to produce significantly larger increases in shoulder ROM and took substantially less time to complete when compared with dynamic warm-up protocols.
Melanie A. Mason, Anne C. Russ, Ryan T. Tierney, and Jamie L. Mansell
Context: Exercise can cause fluctuations in blood glucose control in type 1 diabetics. For athletes with type 1 diabetes, maintenance of blood glucose within an ideal range may be difficult.Objective: To determine, in individuals with type 1 diabetes, the effectiveness of the closed loop control system versus the open loop control system in keeping blood glucose levels in the ideal range with exercise. Data Sources: A search of PubMed was conducted in June of 2020 using the Boolean phrases: (closed loop control system OR artificial pancreas) AND type 1 diabetes AND exercise AND ideal range AND adolescents, artificial pancreas AND glucose prediction AND exercise. Study Selection : Titles were reviewed for relevance, the abstract was then assessed for applicability, and finally the full text was examined. Articles were included that examined the percent of time in the ideal blood glucose range when exercise occurred during that day. Articles were excluded that didn’t compare the closed loop and open loop control systems and articles that did not involve exercise. Data Extraction : The PEDro scale was used to determine the methodological quality of the included studies. The measure addressed was the percent of time in the ideal blood glucose range of 70-180 mg/dL. 95% Confidence Intervals and Cohen’s D were calculated for each article. Data Synthesis : The search yielded 268 articles and 3 were selected for inclusion. The two randomized controlled trials scored 9/10 on the PEDro scale and the randomized two-arm crossover clinical trial scored 9/10 on the PEDro scale. Percent time spent in the ideal blood glucose range when exercise was performed was significantly higher in the closed loop group versus the open loop group in each of the three studies. In one randomized control trial, mean time in the ideal range was 71.3% (SD = 17.6, 95% CI = 62.5, 80.10) in the closed loop group versus 64.7% (SD = 13.3, 95% CI = 58.1–71.4) in the open loop group. Cohen’s D was 0.4. In the second randomized control trial, mean time in the ideal range was 73.5% (SD = 8.4, 95% CI = 70.1, 76.9) for the closed loop group versus 50% (SD = 26.8, 95% CI = 39.1, 60.9). Cohen’s D was 1.2. The two-arm crossover clinical trial resulted in a mean time in target range of 84.1% (SD = 11.5, 95% CI = 79.0, 89.2) in the closed loop group versus 68.7% (SD = 13.9, 95% CI = 62.5, 74.9) in the open loop group. Cohen’s D was 1.2. Conclusions : For adolescents with type 1 diabetes who exercise, the closed loop control system maintains blood glucose levels in the ideal range for a longer percent of time versus an open loop system. Each patient should be evaluated on a case-by-case basis with his/her healthcare team. Future research should examine the closed loop control system on specific energy systems.
Sierra Hakanson, Samuel T. Johnson, Emily C. Norcross, and Cathleen N. Brown
Clinical Scenario: Ulnar collateral ligament injuries are common in baseball pitchers, with excessive elbow varus torque linked to medial elbow injuries. Trunk tilt, or motion in the frontal plane, could be an identifiable and modifiable factor in medial elbow loading. Clinical Question: In high school through professional baseball pitchers, how does increased contralateral trunk tilt compared with no/limited contralateral trunk tilt influence elbow varus torque? Summary of Key Findings: Four studies were included: all were labeled as “controlled” or “descriptive laboratory studies,” representing cross-sectional observational analytic design. One study compared biomechanics of professional pitchers with and without ulnar collateral ligament reconstruction. Two studies measured biomechanics in college pitchers, one of which also included simulations of joint angles. The fourth study measured biomechanics of high school pitchers. All studies measured trunk tilt and its relationship to elbow varus torque, with 3 of the studies linking increased contralateral trunk tilt with increased elbow varus torque. Clinical Bottom Line: Moderate evidence indicated as contralateral trunk tilt increased, so did elbow varus torque, indicating trunk tilt may be a modifiable factor to decrease medial elbow loading during pitching. Strength of Recommendation: Majority consistent findings from the level 3 cross-sectional observational analytic designs suggest grade B evidence in support of trunk tilt as a factor in increasing elbow varus torque.
Germanna M. Barbosa, Larissa P. Ribeiro, Ana B. Nasser, Gretchen D. Oliver, and Paula R. Camargo
Context: Understanding the musculoskeletal adaptations in the shoulder complex of varying ages of tennis athletes may suggest preventive protocols and conditioning and rehabilitation programs to this population. This study aimed to generate a bilateral descriptive profile of shoulder flexibility, scapular and clavicular position, and muscle strength in pediatric and adult amateur tennis athletes. The outcome measures were compared between groups and sides. The number and percentage of athletes “at risk” according to cutoff values for shoulder range of motion (ROM) were also analyzed. Design: Cross-sectional study. Methods: 36 pediatric and 28 adult amateur tennis athletes were tested. Outcome measures were ROM of shoulder flexion, abduction, internal and external rotation, posterior capsule tightness, pectoralis minor index (PMI), scapular upward rotation, clavicular elevation, and strength of the external rotators, serratus anterior, and lower trapezius of the dominant/nondominant sides. Results: Pediatric athletes had greater dominant side external rotation (P = .01) and total ROM (P = .04), increased Low Flexion test (P = .01), and decreased PMI (P = .01) compared with the adults. Bilaterally, the pediatric athletes had greater dominant side external rotation ROM (P < .01) and decreased PMI (P = .002) as compared with their nondominant side, whereas the adults displayed lower values on posterior capsule tightness (P = .01) and decreased PMI (P = .02) on their dominant side compared with their nondominant side. For the remaining outcomes, no interaction effects were observed. The cutoff values for shoulder ROM showed that several athletes were “at risk” of shoulder problems. Conclusion: Upper extremity adaptations at the shoulder are present in both pediatric and adult tennis athletes. These data can assist clinicians in better understanding the biomechanical adaptations in the shoulder of amateur tennis athletes in different age groups.