The Impact of Squat Velocity on Force, Power, and Muscle Activity

The squat is a thoroughly examined movement pattern and commonly used in sport performance training protocols, rehabilitation programs, and recreational exercise. Previous research measuring absolute strength has shown hamstring muscle activity in a six-repetition max barbell back squats. PURPOSE: The purpose of this study is to examine the effects of varying squat velocities (25, 50, 75 deg/s) on force, power, and the activation of the quadricep and hamstring muscles. Using a single-blind randomized research design, we hypothesized that hamstring muscle activity will increase at faster squat velocities. Our secondary hypothesis is that peak power will occur at 50 deg/s and peak force will occur at 25 deg/s. Muscle activity for both the hamstring and quadriceps was measured as root mean square (RMS) electromyography (EMG) and expressed as a percentage of the maximum voluntary contraction (MVC). Muscle activity, force output, and power output were measured over five consecutive repetitions of each velocity in a randomized order. METHODS: Twelve healthy adults (10 males, 2 females) participated in this investigation. Three Delsys Trigno EMG electrodes were placed on the right leg of all participants as they performed the MVC and squat trials on the isokinetic machine. One was placed on the posterior side (biceps femoris [BF]) to measure hamstring activity and two were placed on the anterior side (vastus medialis [VM] and vastus lateralis [VL]) to measure quadricep activity. An isokinetic training machine was used to test the participant’s squat performance at pre-set velocities (Ariel Computerized Exercise System, CA). These machines have been used to measure force and power relationships. MVC was found using an adjustable bench with a padded immovable leg extension attachment. For the quadriceps, the participant sat on the bench in an upright position with the leg extended to approximately 110 degrees against the attachment. Hamstring MVC was measured in a standing position with the leg of interest flexed to approximately 110 degrees with the leg extension attachment behind the lower leg. Three trials of MVC were performed for both knee flexion and extension so results during squat trials can be expressed as a percentage of MVC. Following the MVC, participants then underwent experimental trials. The squat movement pattern was standardized to a depth of 90 degrees of knee flexion measured via goniometry and maintained during each trial using an adjustable height box, set to a predetermined height. Feet were instructed to remain at approximately shoulder width with knees tracking along the same line as the feet to avoid knee misalignment to avoid injury and potentially alter muscle activity. Five consecutive repetitions at each velocity (25, 50, and 75 deg/s) were performed with at least two minutes of rest between trials. For each trial, repetitions two, three, and four were used to determine average and peak power and force. RESULTS: To determine the magnitude of BF muscle activity, we compared it to the degree of quadricep muscle activity (VL:BF and VM:BF) for each squat velocity and analyzed using a one-way ANOVA. This relative hamstring muscle activity was highest at 75 deg/s for VL:BF at 3.84% and at 50 deg/s for VM:BF at 4.59% However, the difference in BF activity involved at each squat velocity was not statistically significant (p = 0.2973). The highest average peak power was achieved at a velocity of 50 deg/s with a value of 1538.19 ± 717.2 W. The greatest average peak force was found at a velocity of 25 deg/s with a value of 1574.08 N ± 605.8 W. When analyzing the peak force within the three velocity groups, a statistically significant difference was found with a p \u3c 0.0001. This was also seen with the average force within the three velocity groups with a p \u3c 0.0001. No statistically significant difference was found for either peak or average power among the three velocity groups. CONCLUSION: When comparing the degree of BF involved during the squat movement, the 25 deg/s had the lowest relative to the quadricep musculature, while both the 50 deg/s and 75 deg/s had higher relative BF activity. As expected, a U-trend was observed with average peak power observed at 50 deg/s, with a decrease at both 25 and 75 deg/s – further confirming the established power-velocity relationship. However, this difference was not statistically significant with our participant size. As velocity increased, force decreased – further confirming the established force-velocity relationship. These results proved to be statistically significant

The minimally-invasive thyroidectomy incision: a histological analysis.

BACKGROUND: Minimally invasive thyroidectomy (MIT) has gained popularity in the surgical management of benign and malignant pathology of the thyroid. One of the main benefits of utilizing this technique is the use of smaller incisions resulting in increased cosmetic satisfaction. Unfortunately, the retraction required for adequate exposure during MIT may lead to skin damage, impaired wound healing and poor cosmetic outcomes. Some have proposed that excising incision edges prior to closure may improve cosmesis. A review of the literature does not reveal any histologic evidence to support this technique. MATERIAL/METHODS: In this prospective observational study, nine subjects undergoing MIT were identified. Both the superior and inferior skin edges were excised and labeled for orientation. Specimens were sent for hematoxylin and eosin staining and histologic analysis by a staff pathologist. RESULTS: All specimens showed no significant findings such as damage to the architecture of the dermis, acute inflammation, edema or evidence of hemorrhage. Focal blood vessel ectasia within the dermis was identified in three of nine subjects. CONCLUSIONS: Our findings do not yield a histological basis supporting the routine trimming of incisions during MIT. Although no significant findings were noted histologically, further studies are warranted to investigate the long-term cosmetic outcome of MIT incisions

Art Play: Stories of Engaging Families, Inspiring Learning, and Exploring Emotions

Collage is the ultimate playful technique . . . . When you put it all together, you create something new. It is really about trial and error . . . about trying things and making mistakes. It’s about forgiving yourself when you make mistakes, and playfulness lets you do that. —Hanoch Piven, “Living in a Playful Collage” Hanoch Piven, an internationally known collage-caricature artist, visited Omaha, Nebraska, to conduct arts-based workshops for families, teachers, and children. The workshops were organized by the Omaha Family Literacy Partnership (OFLP). The partnership promotes literacy learning among children and their families through community activities such as author and illustrator visits, family book celebrations, storytelling events, book distributions, and puppet shows. The OFLP invited Piven, an author and illustrator of children’s books, because of his connection to literacy. Playful explorations with objects is his method of creating art, and this method was the focus of the workshops

Are large clinical trials in orthopaedic trauma justified?

© 2018 The Author(s). Background: The objective of this analysis is to evaluate the necessity of large clinical trials using FLOW trial data. Methods: The FLOW pilot study and definitive trial were factorial trials evaluating the effect of different irrigation solutions and pressures on re-operation. To explore treatment effects over time, we analyzed data from the pilot and definitive trial in increments of 250 patients until the final sample size of 2447 patients was reached. At each increment we calculated the relative risk (RR) and associated 95% confidence interval (CI) for the treatment effect, and compared the results that would have been reported at the smaller enrolments with those seen in the final, adequately powered study. Results: The pilot study analysis of 89 patients and initial incremental enrolments in the FLOW definitive trial favored low pressure compared to high pressure (RR: 1.50, 95% CI: 0.75-3.04; RR: 1.39, 95% CI: 0.60-3.23, respectively), which is in contradiction to the final enrolment, which found no difference between high and low pressure (RR: 1.04, 95% CI: 0.81-1.33). In the soap versus saline comparison, the FLOW pilot study suggested that re-operation rate was similar in both the soap and saline groups (RR: 0.98, 95% CI: 0.50-1.92), whereas the FLOW definitive trial found that the re-operation rate was higher in the soap treatment arm (RR: 1.28, 95% CI: 1.04-1.57). Conclusions: Our findings suggest that studies with smaller sample sizes would have led to erroneous conclusions in the management of open fracture wounds. Trial registration: NCT01069315 (FLOW Pilot Study) Date of Registration: February 17, 2010, NCT00788398 (FLOW Definitive Trial) Date of Registration: November 10, 2008

Bio-inspired geotechnical engineering: principles, current work, opportunities and challenges

A broad diversity of biological organisms and systems interact with soil in ways that facilitate their growth and survival. These interactions are made possible by strategies that enable organisms to accomplish functions that can be analogous to those required in geotechnical engineering systems. Examples include anchorage in soft and weak ground, penetration into hard and stiff subsurface materials and movement in loose sand. Since the biological strategies have been ‘vetted’ by the process of natural selection, and the functions they accomplish are governed by the same physical laws in both the natural and engineered environments, they represent a unique source of principles and design ideas for addressing geotechnical challenges. Prior to implementation as engineering solutions, however, the differences in spatial and temporal scales and material properties between the biological environment and engineered system must be addressed. Current bio-inspired geotechnics research is addressing topics such as soil excavation and penetration, soil–structure interface shearing, load transfer between foundation and anchorage elements and soils, and mass and thermal transport, having gained inspiration from organisms such as worms, clams, ants, termites, fish, snakes and plant roots. This work highlights the potential benefits to both geotechnical engineering through new or improved solutions and biology through understanding of mechanisms as a result of cross-disciplinary interactions and collaborations

Vitamin D Use and Health Outcomes After Surgery for Hip Fracture

Daily administration of vitamin D is important for maintaining bone homeostasis. The orthopedic community has shown increased interest in vitamin D supplementation and patient outcomes after fracture. The current study used data from a large hip fracture trial to determine the proportion of patients who consistently used vitamin D after hip fracture surgery and to determine whether supplementation was associated with improved health-related quality of life and reduced reoperation rates. The FAITH study is a multicenter trial of elderly patients with femoral neck fracture treated with internal fixation. The current study asked a subset of patients included in the FAITH study about vitamin D supplementation and categorized them as consistent users, inconsistent users, or nonusers. This study also evaluated whether supplementation was associated with improved quality of life and reduced reoperation rates. The final analysis included 573 patients (mean age, 74.1 years; female, 66.3%; nondis-placed fractures, 72.4%). A total of 18.7% of participants reported no use of vitamin D, 35.6% reported inconsistent use, and 45.7% reported consistent use. Adjusted analysis found that consistent supplementation was associated with a 2.42 increase of the Short Form-12 physical component score 12 months postoperatively (P=.033). However, supplementation was not associated with reduced reoperation rates (P=.386). Despite guidelines recommending vitamin D supplementation, a low proportion of elderly patients with hip fracture use vitamin D consistently, suggesting a need for additional strategies to promote compliance. This study found that the use of vitamin D was associated with a statistically significant but not clinically significant improvement in health-related quality of life after hip fracture. Further research is needed to confirm these findings. [Orthopedics. 2017; 40(5):e868-e875.]

Wound surface area as a risk factor for flap complications among patients with open fractures

Copyright © 2018 by the American Society of Plastic Surgeons. Background: Soft-tissue complications often dictate the success of limb salvage and the overall outcome of open fractures. Based on prior work at the R Adams Cowley Shock Trauma Center, the authors hypothesize that wounds larger than 200 cm2 are associated with a greater likelihood of both flap-related reoperation and wound complications among patients requiring soft-tissue reconstruction with a rotational flap or free tissue transfer. Methods: This study was a secondary analysis of Fluid Lavage in Open Wounds trial data that included all patients who received a rotational or free tissue flap transfer for an open fracture. The primary outcome was flap-related reoperation within 12 months of injury. The secondary outcome was wound complication, which included events treated operatively or nonoperatively. Multivariable logistic regression was used to assess the association between wound size and outcomes, adjusting for confounders. Results: Seventeen percent of the 112 patients required a flap-related reoperation. A wound size greater than 200 cm2 was not associated with reoperation in an unadjusted model (p = 0.64) or adjusting for Gustilo type (p = 0.70). The sample had an overall wound complication rate of 47.3 percent. Patients with a wound size of greater than 200 cm2 were three times more likely to experience wound complications (OR, 3.05; 95 percent CI, 1.08 to 8.62; p = 0.04) when adjusting for moderate to severe wound contamination and wound closure in the operating room. Conclusion: The findings of this study demonstrate that wound surface area is an integral determinant for wound complication following soft-tissue flap treatment, but found no association between wound surface area and flap-related reoperation rates