Economy Of Movement Research Articles

Skills Acquisition and Assessment after a Microsurgical Skills Course for Ophthalmology Residents

To assess the impact of a skills course on microsurgical skills acquisition and to investigate the validity of a video-based modified Objective Structured Assessment of Technical Skill (OSATS) assessment tool that has not previously been applied to ophthalmic surgery. Prospective longitudinal cohort study. Fourteen residents were recruited from 20 attendees at the Moorfields Eye Hospital microsurgical skills course for residents. Each resident performed a standardized microsurgical task consisting of the placement of a 10-0 nylon corneal suture into a model eye using an operating microscope with standardized equipment in a standardized environment. Objective measurements were made using the Imperial College Surgical Assessment Device (ICSAD). This is a motion-tracking device returning 3 parameters for economy of movement: total path length, time, and number of individual hand movements. A concurrent video recording was made of each task by 2 independent observers who were masked to the time of the recording relative to the course and the identity of the resident. Video footage was marked in accordance with the OSATS video scoring template. Each resident had motion-tracking analysis performed during corneal suturing before and after the course (total path length, time, and number of individual hand movements), along with concurrent OSATS video scores. Skills improvement after the course was found to be statistically significant for all 3 ICSAD economy of movement parameters: path length, P = 0.001; hand movements, P = 0.012; and time, P = 0.009. Differences in the combined OSATS scores of the 2 raters before and after the course were found to be significant (P = 0.039). Interrater reliability of OSATS scorers was 0.78 (alpha Cronbach). Correlations between the OSATS scores and each of the ICSAD parameters were found to be significant (P<0.001). A video-based OSATS scoring system has significant correlation with the ICSAD motion-tracking parameters, demonstrating concurrent validity between the 2 assessment tools. These data also demonstrate that surgical skill, as measured by a validated motion-tracking system, is significantly improved after a 1-day microsurgical skills course. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Proficiency-gain curve for an advanced laparoscopic procedure defined by observation clinical human reliability assessment (OCHRA)

There is no established method for defining when a surgeon reaches the proficiency plateau in performing a specific operation. The published literature refers to "learning curves" based on retrospective evaluation of operative time, conversion rates, morbidity etc., which lack objectivity and do not address individual human factors. A more useful study of the gain in proficiency by the individual surgeon for a particular operation may be obtained using observational clinical-human reliability assessment (OCHRA). Following an 8-month fellowship in advanced laparoscopic surgery, the surgeon M.T. performed, independently at his own hospital, a prospective series of 20 palliative bypass operations for advanced gastric or pancreatic cancer. Unedited videotapes of gastro-jejunostomy (GJ) or cholecysto-jejunostomy (CJ) were analyzed independently in the training institution by the OCHRA technique. For this surgeon proficiency in executing laparoscopic palliative bypass was reached after the 14th anastomosis when efficient execution (reduction in operative time) was accompanied by significant reduction in technical errors and improved economy of movement (reduction of the economy of movement index from 7-5 to 3-2). The majority of errors were enacted in component tasks associated with intracorporeal suturing. The declining incidence of these errors with experience was an integral component of the proficiency-gain curve. The important performance-shaping factors identified were: concentration lapses (n=1,321), misjudgments (n=209), poor camera work (n=193), fatigue (n=128), and impaired coordination (n=108). This study has confirmed that OCHRA can describe quantitatively the proficiency-gain curve for a laparoscopic operation and indicate the plateau stage when the individual surgeon attains maximal performance in the execution of a specific procedure.

Can Interview Prior to Laparoscopic Simulator Training Predict a Trainee's Skills?

Our institute started laparoscopic simulator training for medical students in 2006. During the training, we observed considerable interindividual differences in laparoscopic skills among those students. This study aimed to investigate the predictive factors that affect laparoscopic skill by assessing the students' training results data. Forty-three, fifth-year medical students were asked several questions and were divided into 2 groups depending on their answers. The participants performed an object-positioning module on a ProMIS simulator (Haptica, Inc., Dublin, Ireland). Execution time, instrument path length, and economy of movement for each trial were recorded on ProMIS. Comparisons of mean performance measures between the 2 groups were made using a Mann-Whitney U test. Interest about laparoscopic surgery and accomplishment in playing piano did not affect the skillfulness significantly. The students who had an interest in television (TV) games completed the task in less time (p = 0.046) and had a shorter left instrument path length (p = 0.012). The students who thought themselves manually dexterous completed the task in less time (p = 0.008). The students who were confident about driving completed the task in less time (p = 0.0247). In our interview, the factors that had a relationship to laparoscopic skills were favorableness to TV games, manual dexterity, and confidence about driving. These results were expected because TV games and driving a car require the same abilities as laparoscopic surgery. Psychomotor, perceptual, or visuospatial ability are essential for good performance. In conclusion, our study suggests that the interview can be an effective measure to examine the aptitude of medical students without the use of a simulator.

Assessment study of insight ARTHRO VR (®) arthroscopy virtual training simulator: face, content, and construct validities.

The aims of this study were to test the face, content, and construct validities of a virtual-reality haptic arthroscopy simulator and to validate four assessment hypothesis. The participants in our study were 94 arthroscopists attending an international conference on arthroscopy. The interviewed surgeons had been performing arthroscopies for a mean of 8.71years (σ=6.94years). We explained the operation, functionality, instructions for use, and the exercises provided by the simulator. They performed a trial exercise and then an exercise in which performance was recorded. After having using it, the arthroscopists answered a questionnaire. The simulator was classified as one of the best training methods (over phantoms), and obtained a mark of 7.10 out of 10 as an evaluation tool. The simulator was considered more useful for inexperienced surgeons than for surgeons with experience (mean difference 1.88 out of 10, P value<0.001). The participants valued the simulator at 8.24 as a tool for learning skills, its fidelity at 7.41, the quality of the platform at 7.54, and the content of the exercises at 7.09. It obtained a global score of 7.82. Of the subjects, 30.8% said they would practise with the simulator more than 6h per week. Of the surgeons, 89.4% affirmed that they would recommend the simulator to their colleagues. The data gathered support the first three hypotheses, as well as face and content validities. Results show statistically significant differences between experts and novices, thus supporting the construct validity, but studies with a larger sample must be carried out to verify this. We propose concrete solutions and an equation to calculate economy of movement. Analogously, we analyze competence measurements and propose an equation to provide a single measurement that contains them all and that, according to the surgeons' criteria, is as reliable as the judgment of experts observing the performance of an apprentice.

Construct validity of the ProMIS laparoscopic simulator

Laparoscopic surgery challenges both the surgical novice and experienced open surgeon with unique psychomotor adaptations. Surgical skills assessment has historically relied on subjective opinion and case experience. Objective performance metrics have stimulated much interest in surgical education over the last decade and proficiency-based simulation has been proposed as a paradigm shift in surgical skills training. New assessment tools must be subjected to scientific validation. This study examined the construct validity of a hybrid laparoscopic simulator with in-built motion tracking technology. Volunteers were recruited from four experience groups (consultant surgeon, senior trainee, junior trainee, medical student). All subjects completed questionnaires and three tasks on the ProMIS laparoscopic simulator (laparoscope orientation, object positioning, sharp dissection). Motion analysis data was obtained via optical tracking of instrument movements. Objective metrics included time, path length (economy of movement), smoothness (controlled handling) and observer-recorded penalty scores. One hundred and sixty subjects completed at least one of the three tasks. Significant group differences were confirmed for number of years qualified, age and case experience. Significant differences were found between experts and novices in all three tasks. Sharp dissection was the strongest discriminator of four recognised laparoscopic skill groups: consultants outperformed students and juniors in all three performance metrics and objective penalty score (p < 0.05), and only accuracy of dissection did not distinguish them from senior trainees (p = 0.261). Seniors dissected faster, more efficiently and more accurately than juniors and students (p < 0.05). ProMIS provides a construct valid laparoscopic simulator and is a feasible tool to assess skills in a cross-section of surgical experience groups. ProMIS has the potential to objectively measure pre-theatre dexterity practice until an agreed proficiency level of dexterity is achieved. Future work should now examine whether training to expert criterion levels on ProMIS correlates with actual operative performance.

The genetic basis of human athletic performance. Why are psychological components so often overlooked?

We have read with interest the recent article in The Journal of Physiology by Williams & Folland (2008), who concluded that human physical performance is essentially multifactorial and determined by a range of environmental (physical training, nutrition and technological aids) and genetic factors. Identifying the genes relevant to human athletic performance has been difficult in the past, because each causal gene makes only a small contribution to overall heritability. Accordingly, the adoption of a ‘single-gene-as-magic-bullet’ philosophy is questionable, especially considering that the 2005 human gene map for physical performance and health-related phenotypes already includes 165 autosomal gene entries and quantitative trait loci, plus five others on the X chromosome (Lippi, 2008). All these genes contribute, however, to generate a cluster of phenotypes. Williams & Folland highlighted that, in addition to the well-established maximal rate of oxygen uptake, at least three other endurance phenotypes (economy of movement, lactate/ventilatory threshold and, potentially, oxygen uptake kinetics) contribute to the endurance performance phenotype (time taken to travel a given distance) seen in elite competition (Williams & Folland, 2008). Evolutionary forces (mutation, environment) apply to elements of the human neural system in precisely the same manner that they do to the physical body. They affect both the intellect and our instincts. Accordingly, human physiological trait variance also has both an environmental and genetic basis, although the classic gene–environment dichotomy is clearly too simplistic to explain the full range of variation for most proximate determinants of athletic performance (Brutsaert & Parra, 2006). It is undeniable that success in competition has a strong physiological basis. ‘Mental’ factors contributing to success in sports include mental toughness, game knowledge, tactical astuteness, team coherence, status of maturity, anticipation and decision making, and, last but not least, motivation to endure pain during training and competition. Aspiration to victory is an additional hallmark of the champion. Earlier studies have shown that genetic factors account for up to 62% of the variance in daily exercise behaviour and up to 83% of the variance in sports participation (Beunen & Thomis, 1999; Bryan et al. 2007). Regardless of the clear heritability of exercise and competition behaviours, prior research on genetics and sports has mainly focused on athletic performance phenotypes (Williams & Folland, 2008), and largely overlooked the genetic basis of psychological phenotypes that would characterize elite and top-class athletes. However, emerging evidence attests that research on the genetic basis of ‘physiological phenotypes’ might provide additional, valuable elements to determine ‘advantageous’ polygenic profiles. As an example, it has been shown that polymorphisms in the gene encoding for the brain-derived neurotrophic factor (BDNF), a growth factor that has a broad influence on central and sensory neuronal function, may exert a direct influence on positive mood and strong effects on ratings of perceived exertion and heart rate in response to a bout of aerobic activity (Bryan et al. 2007). It was also demonstrated that genetic variations of the serotonin transporter gene (5HTT) are closely related to the human adaptive ability to control emotions and might strongly influence aggressiveness, positivism and therefore success in competitions (Maliuchenko et al. 2007). The introduction of high-throughput genotyping technologies and microarray-based epigenetic technology now allow us to explore genome-wide associations, gene expression and gene regulation activity (Lippi, 2008). However, limiting the analysis to ‘physical’ favourable phenotypes would not permit the development of comprehensive predictive models, since a variety of environmental and psychological factors still influence athletic skill and performance. An advantageous physical genotype is not enough to build a top-class athlete, a champion capable of breaking Olympic records, if endurance elite performances (maximal rate of oxygen uptake, economy of movement, lactate/ventilatory threshold and, potentially, oxygen uptake kinetics) (Williams & Folland, 2008) are not supported by a strong mental background.

Reply from Alun G. Williams and Jonathan P. Folland

The weight of evidence suggests, and indeed it is widely accepted, that physical performance phenotypes are highly polygenic (Rankinen et al. 2006; Spurway, 2006). Based on that suggestion and using clearly defined inclusion criteria, in our recent article (Williams & Folland, 2008) we showed that human genetic potential for endurance performance depends on polymorphisms of at least 23 loci and probably many more. We then developed the first genetic algorithm for endurance performance and used this to show that it is extremely unlikely that even a single individual in the world possesses what could be termed a ‘perfect’ polygenic profile for endurance. We concluded that world records should continue to advance, although probably at a steadily reducing rate, purely through an ever-increasing pool of participants that includes individuals with genetic profiles more advantageous for endurance performance. The current letter to the editor advances the notion that ‘mental’ factors make significant contributions to success in sport. For example, mental toughness, tactical astuteness, team coherence, anticipation and decision-making, and motivation to endure pain during training and competition were suggested as key psychological traits. We would agree unreservedly. The qualities that make a champion athlete are legion and, we believe, certainly include those psychological factors suggested. We are aware of the impact that psychological factors can play in sport (Gould et al. 2002) and can have upon endurance-related phenotypes specifically (Crews, 1992). Accordingly we would encourage efforts to explore genetic influences on the psychological traits that influence endurance. Although rather outside our particular fields of expertise, we believe the first steps in identifying genetic influences on psychological traits that influence endurance performance would be to collate evidence to demonstrate that certain psychological traits are unequivocally related to improved endurance performance. In other words, a body of evidence similar to that associating maximal rate of oxygen uptake, economy of movement, lactate/ventilatory threshold and oxygen uptake kinetics (Jones & Carter, 2000) with endurance performance. To the best of our knowledge this has not yet been achieved. Next, evidence from twin or family studies would be useful to confirm and quantify the extent of the genetic (versus environmental) influences on those psychological phenotypes. In other words, evidence similar to that for the maximal rate of oxygen uptake, where heritability estimates are typically around 50% both in sedentary individuals and in terms of their response to training (Klissouras, 1971; Bouchard et al. 1986, 1998, 1999; Fagard et al. 1991). If those steps are taken successfully, researchers could then use their understanding of the underlying neurophysiology to identify candidate genes and examine their association (in cross-sectional or longitudinal studies) with critical psychological phenotypes. The demonstration of such genotype–phenotype associations would justify inclusion of those genetic loci in an updated genetic algorithm for endurance performance. An alternative and more direct approach involves identifying candidate genes for exercise and competition behaviours and investigating their association with endurance performance, irrespective of whether psychological phenotypes are or can be measured. The fact is that if any particular genetic polymorphism is associated with endurance sufficiently, regardless of mechanism, then that polymorphism should be identifiable using a ‘case-control’ study design, comparing elite athletes with non-elite controls. Six of the 23 polymorphisms included in our algorithm fell into this category, i.e. the only evidence of association with an endurance phenotype was from a case-control study with no direct evidence of the mechanism (mental or physical). Therefore, it is possible that some of the identified polymorphisms have neurophysiological and behavioural mechanisms of action, although in most cases there are good reasons for thinking the mechanism is local to skeletal muscle or the cardiovascular system. A further development of research of this kind that, initially at least, completely disregards the likely underlying physiological mechanisms, would be to conduct a genome-wide case-control study that does not have a priori hypotheses regarding particular genes. While this approach is proving fruitful in the study of genotype associations with phenotypes that are overtly related to disease (Altshuler & Daly, 2007), no equivalent study has yet been conducted with phenotypes chosen specifically because they are associated with elite athletic performance. It is probably only a matter of time before this occurs. The information that results can be incorporated into updated versions of the novel genetic algorithm for human endurance that we published recently in this journal (Williams & Folland, 2008). We are grateful to Dr Marc Jones (Staffordshire University, UK) for discussion regarding these issues.

Toward the Economy of Pedestrian Movement in Czech and Slovak Shopping Malls

This article examines changes in shopping behavior in two postcommunist countries, the Czech Republic and Slovakia, by replicating Bitgood and Dukes's study of pedestrian choice point behavior. It also extends the former study by applying the methodology to a different type of intersection and subjecting the results to a random resampling statistical test. A survey conducted via naturalistic observation in selected Czech and Slovak shopping malls is presented. Is the movement of shoppers disorganized and unplanned, or is there a tendency to use the principles of the economy of movement, which suggests that pedestrians tend to move in a way involving the least number of steps? A randomization resampling test with 100,000 samples was performed on the data obtained in shopping malls. It can be concluded that pedestrians tend to avoid unnecessary steps by economizing their trajectories ( t = 11.34, p = .00013). The results, thus, show that a qualitative change occurred in the shopping behavior of Czech and Slovak shoppers (as compared with year 2002), and there is an obvious tendency to minimize the total distance in correspondence with the principles of the economy of movement.

Does Box Model Training Improve Surgical Dexterity and Economy of Movement During Virtual Reality Laparoscopy? A Randomized Trial

Laparoscopy calls for particular skills that can be acquired and evaluated by various simulation methods. Numerous virtual reality (VR) models have been validated as training aids. There is evidence that trainees tend to prefer an inanimate box model trainer to a VR model if they must chose one of these. This randomized, controlled trial evaluated a low-cost box model trainer in 16 gynecological residents having limited experience with laparoscopy. All participants completed 7 basic training tasks on a VR laparoscopic trainer (LapSim). Half of the residents then trained for 3 hours using a structured box model training curriculum. Performance at baseline and after training was assessed using the LapSim, focusing on objective parameters such as time, error, and economy of motion. The residents undergoing box model training exhibited more improvement than did control residents in all parameters of performance: economy of movement, time, and tissue damage. It seems clear from these findings that using a box model trainer to learn laparoscopic skills does in fact improve basic skills as measured by a VR simulator. Improvement was most evident for economy-of-motion parameters, those that appear to be most valid for assessing technical laparoscopic skills. The investigators believe that box model trainers should be a part of comprehensive training curricula in gynecology. In addition, a low-cost box model trainer is an option for teaching hospitals lacking the economic resources needed to establish a VR system.

Energy Expenditure When Walking While Wearing Either a Weighted Vest or a Loaded Backpack

The use of a weighted vest has been advocated as a substitute to a weighted backpack for candidates completing emergency service physical employment standards tests as the weighted vests are considered more comfortable, result in a more upright walking posture and safer to wear. One assumption underpinning the loaded backpack test is that it incurs a rate of aerobic energy expenditure that is related to the aerobic energy demand of the relevant job. However, a change in load distribution may change the economy of movement and thereby alter the rate of aerobic energy expenditure required during the test. Therefore, a factor affecting the capacity to substitute a weighted vest for a loaded backpack is whether or not the wearing of the weighted vest incurs a different rate of aerobic energy expenditure to that incurred by wearing the loaded backpack. PURPOSE: To compare the rate of aerobic energy expenditure when walking while wearing a weighted vest compared to a loaded backpack. METHODS: Nine male and three females (mean ± SE: 25.4 ± 2.4 yr) completed two 4.83 km walking trials in random order at 6.44 km·hr-1 on a motor driven treadmill (0% grade) while wearing either a weighted vest or loaded backpack weighing 20.4 kg. All participants were experienced in wearing the two pieces of equipment. Oxygen uptake (VO2) was measured during min 1-3, 10-13, 20-23, 30-33 and 40-45 of each trial. Rate of aerobic energy expenditure was estimated by the mean of the five measurements. RESULTS: There was no significant difference (p=0.99; p=0.61 after adjustment for height, weight, age and gender) between the mean VO2 measured when the participants were wearing the weighted vest (1625.9 ± 36.4 mLO2·min-1) or the backpack (1625.6 ± 37.9 mLO2·min-1). However, there was a significant interaction between gender and load type (p=0.01), with mean VO2 being higher when wearing the vests in females and backpacks in males. Notwithstanding this interaction, ICC was 0.87 and Limits of Agreement were ±6% of the mean of all measurements. Systematic bias was 0.02%. CONCLUSION: The weighted vest and loaded backpack induced similar rates of aerobic energy expenditure in a standardised walking test. However, there was some evidence of a differential gender effect.

Pediatric exercise physiology symposium: a tribute to Oded Bar-Or

Dr. Oded Bar-Or was a pioneer in the study of children’s physical activity, exercise, and health. His diverse research interests led to numerous scientific explorations on thermoregulation, aerobic and anaerobic capacity, physical activity, economy of movement, obesity, neuromuscular diseases, asthma, cystic fibrosis (CF), and many more. To commemorate the extraordinary contributions that Dr. Bar-Or made to the study of exercise and youth, a symposium on pediatric exercise physiology was held at the CSEP’s 2006 Annual Meeting in Halifax. The papers in the following pages include the four papers presented by international colleagues in his memory.

Globalization, development, and human security

Notes on Contributors * Preface * Abbreviations and Acronyms * Introduction * Part 1 - Globalization and the Transformed Context of Development * Chapter 1 Globalism, Regionalism and Interregionalism * Bjorn Hettne * Chapter 2 Foreign Aid: Reports of its Death Greatly Exaggerated * Peter Burnell * Chapter 3 The Heavily Indebted Poor Countries (HIPC) Initiative: Old Wine in a New Bottle? * Fantu Cheru * Chapter 4 Globalisation and Democracy in the Developing World * Jeffrey Haynes * Part 2- Globalization, Development and Human Security * Chapter 5 Globalisation and Human Security * Caroline Thomas * Chapter 6Health in Development * Sandra J. MacLean * Chapter 7 HIV/AIDS in a Globalised World: An Uneven pandemic in an Unequal World * Nana K. Poku * Chapter 8 Transformation and Constriction: Globalisation and Human Rights in the Third World * Bonny Ibhawah * Chapter 9 The Political Economy of Globalisation and Grassroots Movements * Dong-Sook S. Gills * Chapter 10Gender, Power and Governance in a Globalising World * Jane Parpart * Index

Motion Analysis: A Validated Method for Showing Skill Levels in Arthroscopy

The purpose of this study was to show the validity of a motion analysis system in its ability to differentiate between surgeons and non-surgeons when performing simple arthroscopic tasks. We divided 35 subjects into a surgeons group (n = 20) and a non-surgeons group (n = 15). The surgeons group was further subdivided based on the amount of previous arthroscopic experience. Each participant performed 2 separate simulated arthroscopic tasks while being assessed with motion analysis equipment. The time taken, total path length, and number of movements were recorded. A significant difference in performance was identified between surgeons and non-surgeons (P < .0001) and between senior and junior surgeons (P < .05). We identified trends toward decreased time taken and improved economy of movement with increasing arthroscopic experience. This study shows the validity of a motion analysis system as a means of objective assessment of arthroscopic skills in orthopaedics. The system has been shown to differentiate between non-surgeons, junior surgeons, and senior surgeons in performing simple arthroscopic tasks. In the context of concerns regarding reductions in training time, this study validates the use of a simple, affordable, and reliable means of objective assessment of arthroscopic skills and training in such skills. The motion analysis system could subsequently be used as an adjunct to more traditional methods of assessment when planning strategies to teach, learn, and practice arthroscopic skills in the future.

Haptic Feedback Can Provide an Objective Assessment of Arthroscopic Skills

The outcome of arthroscopic procedures is related to the surgeon's skills in arthroscopy. Currently, evaluation of such skills relies on direct observation by a surgeon trainer. This type of assessment, by its nature, is subjective and time-consuming. The aim of our study was to identify whether haptic information generated from arthroscopic tools could distinguish between skilled and less skilled surgeons. A standard arthroscopic probe was fitted with a force/torque sensor. The probe was used by five surgeons with different levels of experience in knee arthroscopy performing 11 different tasks in 10 standard knee arthroscopies. The force/torque data from the hand and tool interface were recorded and synchronized with a video recording of the procedure. The torque magnitude and patterns generated were analyzed and compared. A computerized system was used to analyze the force/torque signature based on general principles for quality of performance using such measures as economy in movement, time efficiency, and consistency in performance. The results showed a considerable correlation between three haptic parameters and the surgeon's experience, which could be used in an automated objective assessment system for arthroscopic surgery. Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Does box model training improve surgical dexterity and economy of movement during virtual reality laparoscopy? A randomised triala

Laparoscopic box model trainers have been used in training curricula for a long time, however data on their impact on skills acquisition is still limited. Our aim was to validate a low cost box model trainer as a tool for the training of skills relevant to laparoscopic surgery. Randomised, controlled trial (Canadian Task Force Classification I). University Hospital. Sixteen gynaecologic residents with limited laparoscopic experience were randomised to a group that received a structured box model training curriculum, and a control group. Performance before and after the training was assessed in a virtual reality laparoscopic trainer (LapSim and was based on objective parameters, registered by the computer system (time, error, and economy of motion scores). Group A showed significantly greater improvement in all performance parameters compared with the control group: economy of movement (p=0.001), time (p=0.001) and tissue damage (p=0.036), confirming the positive impact of box-trainer curriculum on laparoscopic skills acquisition. Structured laparoscopic skill training on a low cost box model trainer improves performance as assessed using the VR system. Trainees who used the box model trainer showed significant improvement compared to the control group. Box model trainers are valid tools for laparoscopic skills training and should be implemented in the comprehensive training curricula in gynaecology.

Transfer validity of laparoscopic knot-tying training on a VR simulator to a realistic environment: A randomized controlled trial

Laparoscopic suturing is one of the most difficult tasks in endoscopic surgery, requiring extensive training. The aim of this study was to determine the transfer validity of knot-tying training on a virtual-reality (VR) simulator to a realistic laparoscopic environment. Twenty surgical trainees underwent basic eye-hand coordination training on a VR simulator (SIMENDO, DelltaTech, Delft, The Netherlands) until predefined performance criteria were met. Then, they were randomized into two groups. Group A (the experimental group) received additional training with the knot-tying module on the simulator, during which they had to tie a double laparoscopic knot ten times. Group B (controls) did not receive additional manual training. Within a week the participants tied a double knot in the abdominal cavity of an anaesthetized porcine model. Their performance was captured on digital video and coded. Objective analysis parameters were: time taken to tie the knot and number of predefined errors made. Subjective assessments were also made by two laparoscopic surgeons using a global rating list with a five-point Likert scale. Trainees in group A (n = 9) were significantly faster than the controls (n = 10), with a median of 262 versus 374 seconds (p = 0.034). Group A made a significantly lower number of errors than the controls (median of 24 versus 36 errors, p = 0.030). Subjective assessments by the laparoscopic experts did not show any significant differences in economy of movement and erroneous behavior between the two groups. Surgical trainees who received knot-tying training on the VR simulator were faster and made fewer errors than the controls. The VR module is a useful tool to train laparoscopic knot-tying. Opportunities arose to improve simulator-based instruction that might enhance future training.

Endurance Exercise Training to Improve Economy of Movement of People With Parkinson Disease: Three Case Reports

Even early in Parkinson disease (PD), individuals have reduced economy of movement. In this case report, the effects of endurance exercise training are examined on walking economy and other measures for 3 individuals in early and middle stages of PD. The patients were 1 woman and 2 men with PD, aged 52 to 72 years, classified at Hoehn and Yahr stages 2 to 2.5. Each patient completed 4 months of supervised endurance exercise training and 12 months of home exercise, with monthly clinic follow-up sessions. Strategies were included to enhance adherence to exercise. The main outcome measure was economy of movement (rate of oxygen consumption during gait) measured at 4 treadmill speeds. Secondary outcome measures included the Unified Parkinson's Disease Rating Scale (UPDRS), Continuous-Scale Physical Functional Performance Test (CS-PFP), Functional Reach Test (FRT), and Functional Axial Rotation Test (FAR). Economy of movement improved for all 3 patients after 4 months of supervised exercise and remained above baseline at 16 months. Two patients also had scores that were above baseline for UPDRS total score, CS-PFP, FRT, and FAR, even at 16 months. : Evidence from these 3 individuals suggests that gains may occur with a treadmill training program that is coupled with specific strategies to enhance adherence to exercise.

Assessment of Construct Validity of a Virtual Reality Laparoscopy Simulator

The aim of this study was to assess whether virtual reality (VR) can discriminate between the skills of novices and intermediate-level laparoscopic surgical trainees (construct validity), and whether the simulator assessment correlates with an expert's evaluation of performance. Three hundred and seven (307) participants of the 19th-22nd Davos International Gastrointestinal Surgery Workshops performed the clip-and-cut task on the Xitact LS 500 VR simulator (Xitact S.A., Morges, Switzerland). According to their previous experience in laparoscopic surgery, participants were assigned to the basic course (BC) or the intermediate course (IC). Objective performance parameters recorded by the simulator were compared to the standardized assessment by the course instructors during laparoscopic pelvitrainer and conventional surgery exercises. IC participants performed significantly better on the VR simulator than BC participants for the task completion time as well as the economy of movement of the right instrument, not the left instrument. Participants with maximum scores in the pelvitrainer cholecystectomy task performed the VR trial significantly faster, compared to those who scored less. In the conventional surgery task, a significant difference between those who scored the maximum and those who scored less was found not only for task completion time, but also for economy of movement of the right instrument. VR simulation provides a valid assessment of psychomotor skills and some basic aspects of spatial skills in laparoscopic surgery. Furthermore, VR allows discrimination between trainees with different levels of experience in laparoscopic surgery establishing construct validity for the Xitact LS 500 clip-and-cut task. Virtual reality may become the gold standard to assess and monitor surgical skills in laparoscopic surgery.

Predictors of Oxygen Uptake and Performance During Tennis

Tennis ball machine tests permit the concurrent measurement of physiological function and groundstroke performance in a sport specific manner. The purpose of this study was to understand further the demands of groundstroke performance during a test with progressively increasing ball frequency, by determining the running speed between strokes, upper and lower limb acceleration and pulmonary gas exchange throughout. Sixteen tennis players (n = 8, male; n = 8, female; all right handed) completed three 4 min stages of hitting against a ball feed frequency of 15, 20, 25 ball.min(-1) interspersed by 8 min of rest. Stepwise multiple regression analysis identified a predictive model of VO2 containing the variables of left arm acceleration and right ankle acceleration but not running speed (p < 0.0001; adjusted r2 = 0.93; left wrist acceleration Beta = 1.04; right ankle acceleration Beta = - 0.12; S. E. E. = 2.61 ml.kg(-1).min(-1)). Regression analysis found that the strongest predictors of stroke performance (ball speed [m.s(-1)] x stroke accuracy [%]) were right wrist acceleration and stroke economy (p < 0.0001; adjusted r2 = 0.28; right wrist acceleration Beta = - 0.59; movement economy Beta = - 0.28). The findings of this study highlight the contribution of limb acceleration and not running speed to the oxygen cost of tennis groundstroke performance.

Scène and Contemporaneity

This second installment of TDR's continuing series on choreography and philosophy addresses dance and temporality. Paula Caspão describes the economy of movement and language as a stuttering, relational, affective field. Frédéric Pouillaude argues that contemporaneity links dance and scène, which in French means both an abstract place for an event and, more concretely, the stage. In a dialogue, Danielle Goldman and Deborah Hay follow up on Goldman's considerations of how improvisation offers “escape routes”—for and from dance, theory, and time.