Mechanical Differences Between Sexes During A Jump Landing

Jump landings are a frequent occurrence in both male and female sports. However, aberrant landing mechanics, such as landing with smaller knee flexion angles (KFA), can increase the likelihood of knee joint injury. Previous research suggests males and females demonstrate different landing mechanics, which could explain the higher incidence of knee injuries in females, such as anterior cruciate ligament (ACL) injury. PURPOSE: The purpose of this study was to compare lower extremity landing biomechanics associated with ACL injury between males and females. We hypothesized that females would land with smaller KFA and greater knee abduction angles (KAA) compared to males. METHODS: Landing biomechanics were assessed in 15 males (23.46±2.75 yrs, 1.77±0.06 m, 77.81±14.01kg) and 15 females (21.24±1.99 yrs, 1.63±0.06 m, 63.15±12.19kg) during a jump landing task. All participants had experience playing sports that required jumping and landing. Separate independent samples t-tests were used to compare KFA at initial contact, knee abduction angle (KAA) at initial contact, peak KFA, and peak KAA between males and females. RESULTS: Males demonstrated larger KFA at initial contact compared to females (16.52±4.55o vs 12.85±4.91o, p=0.04), but smaller KAA at initial contact (3.13±2.07o vs 0.93±052o, po vs 91.88±10.71o, p=0.03) and smaller peak KAA (-2.97±2.0o vs -6.49±4.11o, p=0.004). CONCLUSION: The landing mechanics demonstrated by females may be problematic, as smaller KFA when landing have been associated with higher forces being absorbed, increasing the odds of ACL injury. Furthermore, females also demonstrated greater KAA, which have also been linked with traumatic knee injury. Therefore, females participating in sports involving landing from a jump could benefit from interventions that aim to improve landing kinematics

The Effects Of A Heel Lift On Squat Biomechanics

The barbell squat is an effective exercise for improving lower extremity function. During the descent of a squat, the hip and knee joints flex while the ankle joint dorsiflexes. The hip and knee joints then extend and the ankle joint plantarflexes when standing up. During the squat, some athletes use shoes with an elevated heel or other means of heel elevation to achieve lower squat depth. Research has suggested that use of heel elevation may improve range of motion (ROM) of the lower extremity joints and improve stability of the movement during deep squats, especially with an external load. PURPOSE: The purpose of this study was to compare lower extremity biomechanics during the back squat exercise in a heel-lift (HL) vs non-heel lift (NHL) condition. We hypothesized that the HL condition would result in greater peak knee flexion angles (KFA) and greater net knee joint moments (NJM). METHODS: 25 healthy participants (13 male, 12 female, 23.6±3.14 yrs., 1.70±0.08 m, 72.24±12.86kg) who had back squatted at least once per week for the last three months were recruited for data collection. 2 visits were required from each participant with the first visit involving back squat one-repetition-maximum (1RM) testing (101.62±41.40kg). During the second visit, participants underwent 3-D biomechanical analyses for the back squat with and without heel lift. Participants performed three repetitions at 75% 1RM for each condition in a randomized order, with a five-minute rest period. Squat velocity was controlled for by using a metronome set to 20 beats per minute. The 2nd of the three repetitions was used for analysis. Paired samples T-tests were used to compare peak knee NJM and peak KFA between the HL and NHL conditions. RESULTS: No differences were found between HL and NHL for knee NJM (2.79±0.96 Nm/kg-1vs 2.7±0.79 Nm/kg-1, p=0.72) or peak KFA (126.03±15.73o vs 125.8±15.39o, p=0.83) CONCLUSION: Results contradict our hypothesis, as the HL did not increase the participants KFA or knee NJM. These results suggest that shoe type used during the back squat exercise may be left up to user preference as to what is comfortable for them. Future studies may aim to see if adding a HL influences lower extremity biomechanics when the load is closer to 1RM, or in other squat variations

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020

The Ballantrae ophiolite, Scotland: an Ordovician island arc - marginal basin assemblage

A recent study described a recessive ATPase activating germ-line mutation in smooth-muscle myosin (smmhc/myh11) underlying the zebrafish meltdown (mlt) phenotype. The mlt zebrafish develops intestinal abnormalities reminiscent of human Peutz-jeghers syndrome (PJS) and juvenile polyposis (JP). To examine the role of MYH11 in human intestinal neoplasia, we searched for MYH11 mutations in patients with colorectal cancer (CRC), PJS and JP. We found somatic protein-elongating frameshift mutations in 55% of CRCs displaying microsatellite instability and in the germ-line of one individual with PJS. Additionally, two somatic missense mutations were found in one microsatellite stable CRC. These two missense mutations, R501L and K1044N, and the frameshift mutations were functionally evaluated. All mutations resulted in unregulated molecules displaying constitutive motor activity, similar to the mutant myosin underlying mlt. Thus, MYH11 mutations appear to contribute also to human intestinal neoplasia. Unregulated MYH11 may affect the cellular energy balance or disturb cell lineage decisions in tumor progenitor cells. These data challenge our view on MYH11 as a passive differentiation marker functioning in muscle contraction and add to our understanding of intestinal neoplasi