A Novel Case Study Approach to the Investigation of Leg Strength Asymmetry and Rugby League Player's Multidirectional Speed.

ABSTRACT: Helme, M, Emmonds, S, Low, C, and Till, K. A novel case study approach to the investigation of leg strength asymmetry and Rugby League player's multidirectional speed. J Strength Cond Res 38(5): 941-947, 2024-Leg strength and multidirectional speed qualities have repeatedly been linked with increased performance during Rugby League (RL) match play and associated with career attainment. However, very little of this evidence for strength has been gained through unilateral measurements with no study available that has examined the impact of strength asymmetry, in this population, on speed qualities in RL players. Therefore, this study examined the association between unilateral strength, and as a novel development, the subject with the most extreme asymmetry was identified for further analysis. Fifty RL players undertook the rear foot elevated split squat 5 repetition maximum, 20-m linear sprint, and modified 505 change of direction test. The mean leg strength for the group was 88.92 ± 12.59 kg; when divided by body mass, the mean relative strength (REL) was 1.03 ± 0.17 kg·kg -1 , and the mean asymmetry was 3.21 ± 5.70%. The subject with the greatest asymmetry (subject A) had an imbalance of 33% and a mean leg strength of 75 kg (REL = 0.78 kg·kg -1 ) and a body mass 1 SD above the group mean. Analysis of the group's data and that of subject A did not indicate that leg strength asymmetry was either frequent or harmful, with respect to speed performance. However, relative leg strength was associated with both improved linear and multidirectional speed. Practitioners are recommended to prioritize the development of relative leg strength and disregard the aspiration for between leg performance symmetry.

The associations between unilateral leg strength, asymmetry and injury in sub-elite Rugby League players.

OBJECTIVES: The aim of this study was to analyse the relationship between unilateral leg strength, associated asymmetries and the injuries suffered by sub-elite Rugby League (RL) players in one competitive season. DESIGN: A prospective cohort design was used. METHOD: Unilateral leg strength was measured using the rear foot elevated split squat five repetition maximum test. Injuries were recorded using the Orchard classification system and were used to quantify relative risk (RR), mean severity, burden, player availability and survival time. RESULTS: No measures of leg strength were related to RR, relative leg strength was found to have a significant, but not meaningful correlation with total time lost to lower body injury, lower body injury burden and lower body injury survival time. CONCLUSIONS: The data from the current study indicates a possible positive effect of increasing relative leg strength for injury outcomes in sub-elite RL players. This supports a heuristic that multi-joint lower body strength training for RL players has a potential dual effect of enhancing physical performance and reducing injury time loss, with minimal risk of harm.

Clinical utility of local over general anesthetic tonsillectomy using the BiZact™ device.

PURPOSE: Tonsillectomy under general anesthesia may be viewed preferentially to local anesthesia, due to mitigation of potential airway compromise secondary to intraoperative hemorrhage, patient discomfort and anxiety. However, this is offset by risk of increased trauma (via the endotracheal tube and gag), adverse medication reactions and cost. Here we evaluated the case for use of local anesthesia in tonsillectomy using the BiZact™ (Medtronic) device by comparing surgical outcomes and cost factors across patients where either local or general anesthesia was employed. MATERIALS AND METHODS: Retrospective cohort study of 59 BiZact™ tonsillectomy patients (38 under local anesthetic, and 21 under general anesthetic) from a single surgeon at Tauranga Hospital (public) and Grace Hospital (private) in New Zealand; March 2018 to June 2021. RESULTS: Neither patient group had any primary postoperative hemorrhage and there was comparable incidence of secondary hemorrhage (one case in each cohort). Local anesthetic tonsillectomy was well tolerated with only 2 patients requiring conversion to general anesthetic secondary to anxiety. Local anesthetic proved to be cost-effective, with a halving of hospital length of stay and significant associated overall cost saving, and did not add significantly to operating or total theatre time. Local anesthetic tonsillectomies where perioperative sedation was not required were associated with additional reductions in recovery and overall hospital stay, and cost. CONCLUSIONS: Local anesthetic BiZact™ tonsillectomy is evidently safe and cost-effective.

Is the Rear Foot Elevated Split Squat Unilateral? An Investigation Into the Kinetic and Kinematic Demands.

ABSTRACT: Helme, M, Emmonds, S, and Low, C. Is the rear foot elevated split squat unilateral? An investigation into the kinetic and kinematic demands. J Strength Cond Res 36(7): 1781-1787, 2022-The purpose of the study was to determine the unilateral nature of the rear foot elevated split squat (RFESS). Specifically, the production of force by the rear leg was examined to better understand its role, if any, toward successful completion of the exercise. Male volunteers were recruited (n = 26, age = 23.8 ± 4.6 years, body mass = 88.1 ± 10.7 kg, and height = 1.79 ± 0.1 m), who were recreationally trained and engaged in a structured strength and conditioning program, including both bilateral and unilateral exercises, and had at least 2 years supervised training experience. Subjects participated in an incremental 5 repetition maximum protocol after familiarization. Kinetic data were recorded through 2 independent force plates, 1 integral to the floor and the second mounted on top of solid weightlifting blocks. Kinematic data were captured through 3-dimensional motion analysis. A total of 715 repetitions were analyzed, and the mean contribution of the lead foot to total vertical force production was 84.36 ± 3.6%. An almost certainly small positive correlation (rho = 0.25, confidence interval [CI] 0.18-0.33) was found between the percentage of force produced by the lead foot, with increasing exercise intensity. A most likely trivial, nonsignificant correlation (rho = -0.01, CI -0.09 to 0.06) with rear foot force production, representing the mass of the rear leg. Data from this study do not indicate that the rear foot contributes to the kinetic demands of the exercise and therefore suggests that the RFESS is a valid unilateral exercise.

The energetic, kinematic and kinetic responses to load carried on the back, on the head and in a doublepack.

The determinants of energy saving phenomena reported for load carried on the head, back and in a doublepack remain unclear. This study compared the energetic, kinematic and kinetic responses to head (H), back (B) and doublepack (DP) loading. Fifteen volunteers walked on an instrumented treadmill at 3 km.h-1 with 0, 3, 12 and 20 kg in each loading method. Whole body motion, ground reaction forces (GRF) and metabolic cost were measured. H was less economical than B (p = 0.014) and DP (p = 0.010). H was also associated with increased step length (p = 0.045), decreased cadence (p = 0.001), greater trunk (p < 0.001) and hip (p < 0.001) extension and greater minimum vertical GRF (p = 0.001) than B and DP. In conclusion, no energy saving was found for head- or back-loading but economy may be improved with methods that cause smaller perturbations from unloaded walking. Practitioner summary: Energy saving phenomena have been reported for load carried on the head, back and in a doublepack, yet the determinants are unclear. This study shows that smaller perturbations from unloaded to loaded walking are associated with improved economy for certain load carriage conditions, such as the doublepack.

Does lower-limb asymmetry increase injury risk in sport? A systematic review.

OBJECTIVE: The aim of this review was to synthesize the current understanding relating to the risks of lower body functional asymmetry with injury in athletic populations. METHODS: An iterative data mining and sampling approach was used to construct a search phrase from key words, which were used to identify studies within SPORTdiscus, Medline and Academic Search Complete databases. Additional references were sourced from the reference lists of these articles. RESULTS: After screening, 31 papers were reviewed, from an initial search identifying 302 possible studies. A total of 6228 participants were involved in the studies, of which soccer players were the most observed sporting demographic (n = 2171). Of the 31 studies reviewed eight found no statistical association between lower limb asymmetry and injury risk, 10 studies provided partial statistically significant evidence and a further 10 provided statistically significant statistical links. CONCLUSION: Overall moderate to lower quality evidence for functional asymmetry as a risk factor for injury in sport was observed. While the possibility of a relationship between lower limb functional asymmetry and injury risk cannot be ruled out, further higher quality investigations, adopting standardised methodologies, is required.

Inter-individual variability in load carriage economy and comparisons between different load conditions.

Equivocal findings exist for the economy associated with load carried close to the body's centre of mass. Individual variation could explain some of the equivocal findings. This research aimed to examine the extent of individual variation in loaded walking economy. Eighteen females carried load on the back, head and split between the front and back. Individual variation in relative load carriage economy (ELI) was primarily assessed using standard deviation, coefficients of variation (CV) and intraclass correlation coefficients (ICC). There was large inter-individual variation in ELI values with highest mean CV's of 16%, 12% and 10% for head-, back- and combined front and back-loading. Mean ELI values were not significantly different between methods. The large amount of individual variation found here suggests future load carriage research should account for individual variation, particularly when considering sample size and when making inferences on the economy associated with different types of load carriage using group mean data.

Interaction Between Ambient Temperature, Hypoxia, and Load Carriage on Respiratory Muscle Fatigue.

BACKGROUND: While respiratory muscle fatigue is present following load carriage activity at sea level, the effect of environmental conditions on respiratory strength while undertaking load carriage is unknown.METHODS: The effect of thoracic load carriage during walks (5.5 km) in four environments [(thermo-neutral sea level (SL), -10°C (C), 4300 m (H) and 4300 m at -10°C (HC)] was evaluated on respiratory muscle fatigue. Ten subjects completed eight self-paced randomized treadmill walks comprising a variety of gradients, unloaded and loaded (18.2 kg), across the four environments. Respiratory muscle strength was measured via maximal inspiratory pressure (PImax) and expiratory pressure (PEmax) assessments.RESULTS: Submaximal walking in HC elicited respiratory muscle fatigue when compared to SL. Inspiratory muscle fatigue was independent of load. The relative change in PImax from baseline was significantly greater in HC compared to SL (9.6% vs. 1.3%). PEmax showed a significant reduction during HC (-22.3 cmH2O, -14.4%) when compared to the other three environments.CONCLUSION: These results highlight the need to focus on respiratory muscle strength in preparation for exercise in cold hypoxic conditions.Hinde K, Low C, Lloyd R, Cooke C. Interaction between ambient temperature, hypoxia, and load carriage on respiratory muscle fatigue. Aerosp Med Hum Perform. 2018; 89(11):952-960.

A comparison of economy and sagittal plane trunk movements among back-, back/front- and head-loading.

It has been suggested that freedom of movement in the trunk could influence load carriage economy. This study aimed to compare the economy and sagittal plane trunk movements associated with three load carriage methods that constrain posture differently. Eighteen females walked at 3 km.h-1 with loads of 0, 3, 6, 9, 12, 15 and 20 kg carried on the back, back/front and head. Load carriage economy was assessed using the Extra Load Index (ELI). Change in sagittal plane trunk forward lean and trunk angle excursion from unloaded to loaded walking were assessed. Results show no difference in economy between methods (p = .483), despite differences in the change in trunk forward lean (p = .001) and trunk angle excursion (p = .021) from unloaded to loaded walking. We conclude that economy is not different among the three methods of load carriage, despite significant differences in sagittal plane trunk movements. Practitioner summary: This article shows, based on mean data, that there is no difference in economy among back, back/front and head-loading, despite differences in trunk movement. It is possible a combination of factors align to influence individual economy, rather than a single set of factors, applicable to all individuals for each method.

The effect of temperature, gradient, and load carriage on oxygen consumption, posture, and gait characteristics.

PURPOSE: The purpose of this experiment was to evaluate the effect of load carriage in a range of temperatures to establish the interaction between cold exposure, the magnitude of change from unloaded to loaded walking and gradient. METHODS: Eleven participants (19-27 years) provided written informed consent before performing six randomly ordered walking trials in six temperatures (20, 10, 5, 0, -5, and -10 °C). Trials involved two unloaded walking bouts before and after loaded walking (18.2 kg) at 4 km · h-1, on 0 and 10% gradients in 4 min bouts. RESULTS: The change in absolute oxygen consumption (V̇O2) from the first unloaded bout to loaded walking was similar across all six temperatures. When repeating the second unloaded bout, V̇O2 at both -5 and -10 °C was greater compared to the first. At -10 °C, V̇O2 was increased from 1.60 ± 0.30 to 1.89 ± 0.51 L · min-1. Regardless of temperature, gradient had a greater effect on V̇O2 and heart rate (HR) than backpack load. HR was unaffected by temperature. Stride length (SL) decreased with decreasing temperature, but trunk forward lean was greater during cold exposure. CONCLUSION: Decreased ambient temperature did not influence the magnitude of change in V̇O2 from unloaded to loaded walking. However, in cold temperatures, V̇O2 was significantly higher than in warm conditions. The increased V̇O2 in colder temperatures at the same exercise intensity is predicted to ultimately lead to earlier onset of fatigue and cessation of exercise. These results highlight the need to consider both appropriate clothing and fitness during cold exposure.

Elevated expression of BIRC6 protein in non-small-cell lung cancers is associated with cancer recurrence and chemoresistance.

INTRODUCTION: Non-small-cell lung cancer (NSCLC) is an aggressive, highly chemoresistant disease. Reliable prognostic assays and more effective treatments are critically required. BIRC6 (baculoviral inhibitors of apoptosis proteins repeat-containing 6) protein is a member of the inhibitors of apoptosis protein family thought to play an important role in the progression or chemoresistance of many cancers. In this study, we investigated whether BIRC6 expression can be used as a prognostic marker or potential therapeutic target for NSCLC. METHODS: In a retrospective analysis, BIRC6 protein expression was determined for 78 resected primary NSCLCs and nine benign lung tissues. Twenty-nine chemoresistant or chemosensitive subrenal capsule NSCLC tissue xenografts were assessed for BIRC6 expression, using immunohistochemistry, and 13 of them for BIRC6 gene copy number, using array comparative genomic hybridization analysis. The effect of small interfering RNA-induced BIRC6 knockdown on the growth of human NSCLC cell cultures and apoptosis (in combination with cisplatin) was investigated. RESULTS: Elevated BIRC6 protein expression in NSCLC tissues was associated with poor 3-year relapse-free patient survival, lymph node involvement, and advanced pathological tumor, node, metastasis stage. In patient-derived lung squamous cell carcinoma xenografts, chemoresistance was associated with elevated BIRC6 expression and increased gene copy number. Small interfering RNA-induced BIRC6 down-regulation inhibited growth of the NSCLC cells and sensitized the cells to cisplatin. CONCLUSIONS: BIRC6 may play an important role in the malignant progression and chemoresistance of NSCLC. Elevated BIRC6 protein expression may serve as a predictive marker for chemoresistance of NSCLCs and a poor prognostic factor for NSCLC patients. Down-regulation of the BIRC6 gene as a therapeutic approach may be effective, especially in combination with conventional chemotherapeutics.

Super-shedding and the link between human infection and livestock carriage of Escherichia coli O157.

Cattle that excrete more Escherichia coli O157 than others are known as super-shedders. Super-shedding has important consequences for the epidemiology of E. coli O157 in cattle--its main reservoir--and for the risk of human infection, particularly owing to environmental exposure. Ultimately, control measures targeted at super-shedders may prove to be highly effective. We currently have only a limited understanding of both the nature and the determinants of super-shedding. However, super-shedding has been observed to be associated with colonization at the terminal rectum and might also occur more often with certain pathogen phage types. More generally, epidemiological evidence suggests that super-shedding might be important in other bacterial and viral infections.

Herd-level risk factors associated with the presence of Phage type 21/28 E. coli O157 on Scottish cattle farms.

BACKGROUND: E. coli O157 is a bacterial pathogen that is shed by cattle and can cause severe disease in humans. Phage type (PT) 21/28 is a subtype of E. coli O157 that is found across Scotland and is associated with particularly severe human morbidity. METHODS: A cross-sectional survey of Scottish cattle farms was conducted in the period Feb 2002-Feb 2004 to determine the prevalence of E. coli O157 in cattle herds. Data from 88 farms on which E. coli O157 was present were analysed using generalised linear mixed models to identify risk factors for the presence of PT 21/28 specifically. RESULTS: The analysis identified private water supply, and northerly farm location as risk factors for PT 21/28 presence. There was a significant association between the presence of PT 21/28 and an increased number of E. coli O157 positive pat samples from a farm, and PT 21/28 was significantly associated with larger E. coli O157 counts than non-PT 21/28 E. coli O157. CONCLUSION: PT 21/28 has significant risk factors that distinguish it from other phage types of E. coli O157. This finding has implications for the control of E. coli O157 as a whole and suggests that control could be tailored to target the locally dominant PT.

Child abuse and neglect presentations to a pediatric emergency department.

This study describes the epidemiology of reported abuse (physical, sexual, and neglect) in a teaching, metropolitan Pediatric Emergency Department (PED) with approximately 30,000 annual visits. A retrospective chart review was conducted of all cases from the PED that were referred to the Department of Social Work and reported to the Administration for Children's Services (ACS), the New York children's protective services, from May 1996 through December 1998. Demographic information about the victims as well as past medical history, number of previous PED visits, information about the perpetrator and the nature of the injuries were obtained. We identified 106 cases over this period of time that were reported for child abuse or neglect from the PED. Fifty-five percent of cases were reported for suspected physical abuse, 15% for sexual abuse, and 30% for neglect. The suspected perpetrator was the mother in 41% of cases and the father in 21% of cases. Bruises were the most frequent injury reported, seen in 25% of cases. The mean age of the patients was 6.4 years old. They averaged 4.6 previous PED visits. The majority of patients lived near the hospital. Sixty-nine percent of the patients presented for care between the hours of 5 PM and 9 AM. Most of the patients claimed their primary physician was located in a clinic near their home (44%). Only 12.7% were unsure of their primary physician. Significantly more victims (89%) had Medicaid or no insurance compared with other PED patients (71%). Victims did not live in zip codes with lower incomes compared with other PED patients. Upon complete investigation by ACS, 49 cases (46%) were deemed 'indicated,' 21 cases (20%) 'unfounded,' and for the remaining 36 cases (34%) follow-up information could not be determined. The incidence of reported abuse and neglect was lower than previous studies have shown. The majority of reported cases (especially those of sexual abuse) did not have any physical findings at the time of presentation, stressing the need of a careful search for both abuse and neglect.