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.
Nilüfer Kablan, Nuray Alaca, and Yaşar Tatar
Context: Fast and adequate recovery after exercise and activity is important for increasing performance and preventing injuries. Inadequate recovery usually causes changes in the biomechanical and viscoelastic properties of the muscle. Objective: To compare the immediate effect of petrissage massage (PM) and manual lymph drainage (MLD) following submaximal exercise on the biomechanical and viscoelastic properties of the rectus femoris muscle in healthy women. Design: Cross-sectional, repeated-measures. Setting: Marmara University. Participants: 18 healthy female students. Intervention(s): Following the submaximal quadriceps strengthening exercise performed in 3 sets of 8 repetitions with intensity of 75% of 1 maximum repetition, participants’ right leg received a 5-minute PM (PM group) and the contralateral leg received a 5-minute MLD application (MLD group). Main Outcome Measures: Skin temperature was measured using P45 thermographic thermal camera (Flir System; ThermaCAM, Danderyd, Sweden), and muscle tone, biomechanical, and viscoelastic features were measured with a myometer (Myoton AS, Tallinn, Estonia) at baseline, immediately postexercise, post-PM/MLD application, and 10 minutes postexercise. Results: In the PM group, the tonus (P = .002) and stiffness (P < .001) values measured after the massage and at the end of the 10-minute resting period were found to be statistically different than those measured right after the exercise (P < .05). Relaxation time and creep values at all measurement times were significantly different (P < .05). In the MLD group, it was observed the tonus (P < .001), stiffness (P = .025), and relaxation time (P < .01) values decreased significantly after the MLD compared with the values measured after the exercise; however, the creep value was found to be significantly different in all measurements (P < .05). Conclusion: PM and MLD reduce passive tissue stiffness and improve the extent of muscle extensibility over time against the muscle tensile strength. PM and MLD are therapeutic methods that can be used to support tissue recovery after exercise and prevent injuries.
Matías Henríquez, Aitor Iturricastillo, Arturo González-Olguín, Felipe Herrera, Sonny Riquelme, and Raul Reina
This study compared physical performance in a group of international cerebral palsy football players during two formats of small-sided games (SSGs) and performance in a simulated game (SG) according to players’ sport classes (FT1, FT2, and FT3). Internal load (heart rate and rating of perceived exertion) and external load (total distance, distance covered at different velocities, maximum speed reached, acceleration, and deceleration) were obtained with global positioning system devices during two formats of SSGs (2-a-side/SSG2 and 4-a-side/SSG4) and an SG (7-a-side). SSG2 demands faster actions compared with SSG4/SG, and significant differences and large effect sizes were found in the distance covered in Speed Zones 5 (16.0−17.9 km/hr) and 6 (>18.0 km/hr; p < .05;
Dhinu J. Jayaseelan, Cesar Fernandez-de-las-Penas, Taylor Blattenberger, and Dean Bonneau
Clinical Scenario: Plantar heel pain is a common condition frequently associated with persistent symptoms and functional limitations affecting both the athletic and nonathletic populations. Common interventions target impairments at the foot and ankle and local drivers of symptoms. If symptoms are predominantly perpetuated by alterations in central pain processing, addressing peripheral impairments alone may not be sufficient. Clinical Question: Do individuals with chronic plantar heel pain demonstrate signs potentially associated with altered central pain processing? Summary of Key Findings: After searching 6 electronic databases (PubMed, CINAHL, Scopus, SportDiscus, Cochrane, and PEDro) and filtering titles based on predetermined inclusion and exclusion criteria, 4 case-control studies were included. All studies scored highly on the Newcastle-Ottawa Scale for quality assessment. Using pressure pain thresholds, each study found decreased pressure pain hypersensitivity locally and at a remote site compared to control groups, suggesting the presence, to some extent, of altered nociceptive pain processing. Clinical Bottom Line: In the studies reviewed, reported results suggest a possible presence of centrally mediated symptoms in persons with plantar heel pain. However, despite findings from these studies, limitations in appropriate matching based on body mass index and measures used suggest additional investigation is warranted. Strength of Recommendation: According to the Oxford Centre for Evidence-Based Medicine, there is evidence level C to suggest chronic plantar heel pain is associated with alterations in central pain processing.