Context: Calculating the resistance provided by elastic resistance is essential with the aim of adjusting the load and controlling the progression of the exercises in programs using elastic resistance. This study aimed (1) to establish a model of the force elongation for CLX bands; (2) to examine whether these models are altered by different aspects of band elongation: the phase of elongation and shortening (concentric and eccentric phases), the elongation speed, and the initial resting length; and (3) to determine the resistance value for 100% of elongation in each color and to compare it with the values reported by Theraband. Design: Cross‐sectional. Methods: Ten CLX bands of each color were elongated by 2 experienced researchers to establish their elongation force curves in series of 10 repetitions per band using a Smith machine for an anchor, examining whether elongation force models were affected by elongation and shortening phases using one 4-loop CLX band stretched to 100% and at 0.50 m/s, elongation speed stretching two 4-loop CLX bands at 0.50 m/s and at 0.70 m/s, and different starting lengths using 3 CLX bands (2, 3, and 4 loops) stretched at 0.50 m/s. Results: No differences were found in the comparisons between phases, speeds, or different start lengths (mean errors ranged from 0.01 [0.07 N] for the blue band to 2.97 [0.94 N] for the gold band). Our values were higher than the reference values provided by Theraband for all colors, ranging from 2.3% to 33.1%. Conclusions: Our findings show that the values provided by the brand underestimate the resistance provided by CLX bands. To solve this, regression equations are provided so professionals can calculate the resistance of CLX bands based on their elongation. In addition, these models are not influenced by the phase of elongation and shortening, the elongation speed, and the initial resting length.
Rodrigo Martín-San Agustín, Francesc Medina-Mirapeix, Mariano Gacto-Sánchez, Germán Cánovas-Ambit, and Aurelio Arenas-Della Vecchia
Tomoya Ishida, Mina Samukawa, Yuta Koshino, Takumi Ino, Satoshi Kasahara, and Harukazu Tohyama
Asymmetry in knee extensor moment during double-leg squatting was observed after anterior cruciate ligament reconstruction, even after the completion of the rehabilitation program for return to sports. The purpose of this study was to clarify the association between asymmetry in the knee extensor moment and pelvic rotation angle during double-leg squatting after anterior cruciate ligament reconstruction. Twenty-four participants performed double-leg squatting. Kinetics and kinematics during squatting were analyzed using a 3-dimensional motion analysis system with 2 force plates. The limb symmetry index of knee extensor moment was predicted by the pelvic rotation angle (R2 = .376, P = .001). In addition, the pelvic rotation and the limb symmetry index of the vertical ground reaction force independently explained the limb symmetry index of the knee extensor moment (R2 = .635, P < .001, β of pelvic rotation = −0.489, β of vertical ground reaction force = 0.524). Pelvic rotation toward the involved limb was associated with a smaller knee extensor moment in the involved limb than in the uninvolved limb. The assessment of pelvic rotation would be useful for partially predicting asymmetry in the knee extensor moment during double-leg squatting. Minimizing pelvic rotation may improve the asymmetry in the knee extensor moment during double-leg squatting after anterior cruciate ligament reconstruction.
Ling Li, Yu Song, Maddy Jenkins, and Boyi Dai
Biomechanical behavior prior to landing likely contributes to anterior cruciate ligament (ACL) injuries during jump-landing tasks. This study examined prelanding knee kinematics and landing ground reaction forces (GRFs) during single-leg and double-leg landings in males and females. Participants performed landings with the dominant leg or both legs while kinematic and GRF data were collected. Single-leg landings demonstrated less time between prelanding minimal knee flexion and initial ground contact, decreased prelanding and early-landing knee flexion angles and velocities, and increased peak vertical and posterior GRFs compared with double-leg landings. Increased prelanding knee flexion velocities and knee flexion excursion correlated with decreased peak posterior GRFs during both double-leg and single-leg landings. No significant differences were observed between males and females. Prelanding knee kinematics may contribute to the increased risk of ACL injuries in single-leg landings compared with double-leg landings. Future studies are encouraged to incorporate prelanding knee mechanics to understand ACL injury mechanisms and predict future ACL injury risks. Studies of the feasibility of increasing prelanding knee flexion are needed to understand the potential role of prelanding kinematics in decreasing ACL injury risk.
Christopher J. Burcal
Unai Latorre Erezuma, Maialen Zelaia Amilibia, Ander Espin Elorza, Camilo Cortés, Jon Irazusta, and Ana Rodriguez-Larrad
This study assessed the effectiveness of a passive back support exoskeleton during a mechanical loading task. Fifteen healthy participants performed a simulated patient transfer task while wearing the Laevo (version 2.5) passive back support exoskeleton. Collected metrics encompassed L5-S1 joint moments, back and abdominal muscle activity, lower body and back kinematics, center of mass displacement, and movement smoothness. A statistical parametric mapping analysis approach was used to overcome limitations from discretization of continuous data. The exoskeleton reduced L5-S1 joint moments during trunk flexion, but wearing the device restricted L5-S1 joint flexion when flexing the trunk as well as hip and knee extension, preventing participants from standing fully upright. Moreover, wearing the device limited center of mass motion in the caudal direction and increased its motion in the anterior direction. Therefore, wearing the exoskeleton partly reduced lower back moments during the lowering phase of the patient transfer task, but there were some undesired effects such as altered joint kinematics and center of mass displacement. Statistical parametric mapping analysis was useful in determining the benefits and hindrances produced by wearing the exoskeleton while performing the simulated patient transfer task and should be utilized in further studies to inform design and appropriate usage.
Madeline Winans, Kevin M. Biese, Grace Rudek, Madison N. Renner, Julie M. Stamm, and David R. Bell
Attitudes and beliefs of parents about sport specialization may indicate why youth athletes decide to specialize. The purpose of this study was to determine the association between sport specialization level, ice hockey position, and the parent/guardians’ attitudes and beliefs on sport specialization. Our results demonstrate that goalies were the most likely to specialize, and parents of specialized ice hockey players tend to believe that sport specialization helps their child achieve future sporting aspirations. Increased sport specialization may put ice hockey goalies at an increased risk for overuse injuries, and parents’ beliefs about sport specialization may impact their child’s sporting behaviors.
Iván Chulvi-Medrano, Juan Manuel Cortell-Tormo, Sergio Hernández-Sánchez, Moisés Picón-Martínez, and Nicholas Rolnick
Context: Resistance training with blood flow restriction (BFR) has increased in clinical rehabilitation due to the substantial benefits observed in augmenting muscle mass and strength using low loads. However, there is a great variability of training pressures for clinical populations as well as methods to estimate it. The aim of this study was to estimate the percentage of maximal BFR that could result by applying different methodologies based on arbitrary or individual occlusion levels using a cuff width between 9 and 13 cm. Design: A secondary analysis was performed on the combined databases of 2 previous larger studies using BFR training. Methods: To estimate these percentages, the occlusion values needed to reach complete BFR (100% limb occlusion pressure [LOP]) were estimated by Doppler ultrasound. Seventy-five participants (age 24.32 [4.86] y; weight: 78.51 [14.74] kg; height: 1.77 [0.09] m) were enrolled in the laboratory study for measuring LOP in the thigh, arm, or calf. Results: When arbitrary values of restriction are applied, a supra-occlusive LOP between 120% and 190% LOP may result. Furthermore, the application of 130% resting brachial systolic blood pressure creates a similar occlusive stimulus as 100% LOP. Conclusions: Methods using 100 mm Hg and the resting brachial systolic blood pressure could represent the safest application prescriptions as they resulted in applied pressures between 60% and 80% LOP. One hundred thirty percent of the resting brachial systolic blood pressure could be used to indirectly estimate 100% LOP at cuff widths between 9 and 13 cm. Finally, methodologies that use standard values of 200 and, 300 mm Hg far exceed LOP and may carry additional risk during BFR exercise.
Jenna Morogiello, Rebekah Roessler, and Maddison Flowers
Campus recreation is an underserved population lacking specific medical standards, access to on-site medical personnel, and a universal injury surveillance system. The purpose of this study was to retrospectively examine injury epidemiology within a campus recreation center across 4 years. A total of 1,680 injuries were analyzed from one U.S. university with the greatest number of injuries occurring in intramural sports, informal recreation, and club sports, respectively. Of all injuries reported, 73% were musculoskeletal in nature and 9% were from concussions. As most injuries fall outside the scope of basic first aid, on-site medical services should be considered for all campus recreation settings.
Alessandro Piras and Milena Raffi
In many daily and sport situations, people have to simultaneously perceive and process multiple objects and scenes in a short amount of time. A wrong decision may lead to a disadvantage for a team or for a single athlete, and during daily life (i.e., driving, surgery), it could have more dangerous consequences. Considering the results of different studies, the ability to distribute visual attention depends on different levels of expertise and environment-related constraints. This article is a narrative review of the current scientific evidence in the field of eye movements in sports, focusing on the role of microsaccades in sporting task situations. Over the past 10 years, microsaccades have become one of the most increasing areas of research in visual and oculomotor studies and even in the area of sport science. Here, we review the latest findings and discuss the relationships between microsaccades and attention, perception, and action in sports.
Hallie D. Sayre and Tom G. Bowman
A concussed 19-year-old female midfielder on an National Collegiate Athletic Association (NCAA) Division III soccer team reported to the athletic training clinic complaining of a headache that began 4 days previously during a game where she headed several long punts. Despite delayed reporting, the patient returned to full participation without complication 13 days after her injury. The biomechanical data for the impacts she received on the day of injury were much lower than those presented in the literature as causing concussion for male athletes. Therefore, impact magnitude should not be used as an indicator for injury, as smaller, seemingly insignificant impacts can cause concussion.