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 (F 2,56 = 110.054, P < .001), gluteus maximus (F 2,56 = 36.416, P < .001), and TFL (F 2,56 = 108.342, P < .001) muscles among the 3 side bridge exercises. There were significant differences in the Gmed/TFL muscle ratio (F 2,56 = 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.
Tsz Lun (Alan) Chu, Bailey Sommerfeld, and Tao Zhang
Building on recent research examining athlete burnout trajectories, this study implemented the developmental model of sport participation to compare emotional and physical exhaustion, reduced sense of accomplishment, and sport devaluation between age groups (specializing [aged 13–15 years] vs. investment [aged 16–18 years]) and gender (boys vs. girls) among U.S. high school athletes. Participants were 367 high school athletes (M = 15.53; 212 males; 186 specializing) across various individual and team sports who completed a survey assessing their demographic information, sport backgrounds, and burnout perceptions. A 2 × 2 multivariate analysis of covariance, controlling for training hours, showed greater emotional and physical exhaustion and sport devaluation in the investment than the specializing group, but no developmental differences in reduced sense of accomplishment. Contrary to our hypothesis, no gender or interaction effects were found. Findings inform interventions and future research that address the role of developmental stages and gender in athlete burnout.
Aaron S. Fox, Reed Ferber, and Jason Bonacci
Altered gait variability occurs in those with patellofemoral pain and may be relevant to pain progression. We examined gait kinematic and coordination variability between individuals with acute and chronic patellofemoral pain and healthy controls. Eighty-three patellofemoral pain runners (37 men and 46 women) and 142 healthy controls (52 men and 90 women) ran on a treadmill while 3-dimensional lower limb kinematic data were collected. Patellofemoral pain runners were split into acute (n = 22) and chronic (n = 61) subgroups based on pain duration (< and ≥3 mo, respectively). Approximate entropy assessed continuous hip, knee, and ankle kinematic variability. Vector coding calculated coordination variability for select joint couplings. Variability measures were compared between groups using 1-way analysis of variance and post hoc comparisons with Cohen d effect sizes. The chronic patellofemoral pain subgroup displayed higher frontal plane knee kinematic variability compared with controls (P = .0004, d = 0.550). No statistically significant effects for any coordination variability couplings were identified. Minimal differences in gait variability were detected between those with acute and chronic patellofemoral pain and healthy controls.
Dean R. Watson, Andrew P. Hill, and Daniel J. Madigan
Attitudes toward help-seeking will contribute to whether athletes ask for support for performance and mental health issues when needed. While research outside of sport has found perfectionism is related to negative attitudes toward help-seeking, no studies have examined the relationship in sport. The authors provided the first test of whether perfectionism predicted attitudes toward both sport psychology support and mental health support. One hundred and sixty-six collegiate athletes completed measures of perfectionism and attitudes toward sport psychology support and mental health support. Multiple regression analyses revealed that perfectionistic concerns positively predicted closedness and stigma toward sport psychology support and mental health support, and negatively predicted help-seeking toward mental health support. However, perfectionistic strivings negatively predicted stigma toward sport psychology support and mental health support, and positively predicted confidence in sport psychology support and help-seeking toward mental health support. Athletes higher in perfectionistic concerns are less likely to seek support when required.
Georgia A. Bird, Mary L. Quinton, and Jennifer Cumming
This study investigated the relationship between reappraisal and suppression with depression and mental well-being among university athletes. It was hypothesized reappraisal would associate with lower depression and greater mental well-being, whereas suppression would associate with greater depression and reduced mental well-being. Employing a cross-sectional design, 427 participants (M age = 20.18, SD = 1.52; 188 males and 239 females) completed questionnaires assessing mental health and strategy use. Hierarchical multiple regressions revealed reappraisal was positively associated, and suppression negatively associated with mental well-being, ΔR 2 = 4.8%, ΔF(2, 422) = 17.01, p ≤ .001; suppression, β = −0.08, p = .028; reappraisal, β = 0.21, p ≤ .001, but neither were associated with depression, ΔR 2 = 0.4%, ΔF(2, 422) = 1.33, p = .267; suppression, β = 0.06, p = .114; reappraisal, β = 0.03, p = .525. Results highlight reappraisal as correlated with mental well-being in student-athletes, and therefore, reappraisal could be beneficial for managing stress in sport. Reappraisal may implicate how well-being is promoted through sport, but future experimental research is needed to confirm causal relationships.
Erhan Seçer and Derya Özer Kaya
Context: Dynamic stretching (DS) is typically suggested during warm-up protocols. Also, foam rolling (FR), which is applied with a foam cylinder, has increased popularity in recent years. However, the combined effects of DS and FR in improving flexibility, dynamic balance, and agility performance are unclear in current literature. Therefore, this study aim to evaluate and compare the acute effects of DS as well as DS followed by FR (DS + FR) on flexibility, dynamic balance, and agility in male soccer players. Design: This study was a crossover study with a within-subject design. Methods: Thirty volunteer male soccer players (mean age 18.80 [0.66] y) were included in the study. Each participant performed the 2 sessions (DS and DS + FR) on separate occasions in a randomized order, with an interval of 72 hours. All sessions were performed in the indoor gym at the sports club. Flexibility was assessed by sit-and-reach test, dynamic balance was assessed by Y balance test, and agility was assessed by t test. Results: Compared with the pretest results, significant improvement in flexibility was observed in both groups (change = 0.55, percentage change = 2.05, effect size [ES] = 0.15, P = .041; change = 0.64, percentage change = 2.36, ES = 0.20, P = .025; respectively). Balance scores did not significantly improve in either group (change = 0.40, percentage change = 0.45, ES = 0.09, P = .342; change = 0.93, percentage change = 1.02, ES = 0.23, P = .103; respectively). Agility performance significantly improved in both groups (change = −0.12, percentage change = −1.18, ES = 0.19, P = .021; change = −0.21, percentage change = −2.18, ES = 0.38, P = .005; respectively). Conclusions: Both DS and DS + FR improved flexibility and agility and did not affect balance. DS + FR was not superior to DS at improving flexibility and agility as compared only with DS. Both methods are effective warm-up protocols to augment factors related to injury risk and performance. It seems that further studies that investigate the combined effects of FR and DS are needed.
Jeff M. Barrett, Colin D. McKinnon, Clark R. Dickerson, and Jack P. Callaghan
Relatively few biomechanical models exist aimed at quantifying the mechanical risk factors associated with neck pain. In addition, there is a need to validate spinal-rhythm techniques for inverse dynamics spine models. Therefore, the present investigation was 3-fold: (1) the development of a cervical spine model in OpenSim, (2) a test of a novel spinal-rhythm technique based on minimizing the potential energy in the passive tissues, and (3) comparison of an electromyographically driven approach to estimating compression and shear to other cervical spine models. The authors developed ligament force–deflection and intervertebral joint moment–angle curves from published data. The 218 Hill-type muscle elements, representing 58 muscles, were included and their passive forces validated against in vivo data. Our novel spinal-rhythm technique, based on minimizing the potential energy in the passive tissues, disproportionately assigned motion to the upper cervical spine that was not physiological. Finally, using kinematics and electromyography collected from 8 healthy male volunteers, the authors calculated the compression at C7–T1 as a function of the head–trunk Euler angles. Differences from other models varied from 25.5 to 368.1 N. These differences in forces may result in differences in model geometry, passive components, number of degrees of freedom, or objective functions.