Critically appraised topic: the use of vaccination to control the spread of foot-and-mouth disease in Australian livestock in the event of an incursion.

With recent outbreaks of foot-and-mouth disease (FMD) in Indonesia and Bali, industry, government and public concern for its incursion into Australia is increasing. The potential impact of an outbreak on the agricultural industry and national economy could be devastating. To date, research conducted in relation to FMD in Australia predominantly concerns simulations and models performed to predict various outcomes. This project critically appraises the current literature regarding the simulated use of vaccination and its effectiveness for controlling the spread of FMD in Australia in the event of an outbreak. Findings from 10 modelling studies suggest that vaccination is effective at controlling the size and duration of an outbreak (under certain conditions), however, there is less clarity about cost-effectiveness.

Microbial pathogen removal from domestic effluent using coral sand in Kiribati.

AIM: Infiltration experiments aimed to show the effectivity of coral sand to remove micro-organisms in septic tank wastewater treatment system, in South Tarawa, Kiribati. METHODS AND RESULTS: Laboratory experiments evaluated effective microbial removal properties of a packed bed of coral beach sand conditioned with domestic effluent. Bacterial and viral indicators Escherichia coli J6-2, Enterococci faecalis and f-RNA (MS2) bacteriophage, along with viral pathogens adenovirus, echovirus, norovirus and rotavirus, were dosed (at 106 -107  CFU, PFU or genome copies per ml concentration) with effluent to unsaturated coral sand-packed columns. For the conditions simulated, all organisms showed removal efficiencies of >4-Log Removal Values (LRVs) (i.e. >99·99% effective reduction in number). Results revealed that the conditioned coral sand had a higher affinity for attenuating viruses than the bacteria tested. MS2 phage, adenovirus, echovirus, norovirus and rotavirus were absent in leachate from the base of the sand columns. E. coli J6-2 and E. faecalis were recovered at 100 -101  CFU (colony forming units) per ml in the column effluent, following a dosage of 106  CFU per ml. Destructive sampling of the columns after experiments revealed that a high proportion of viral pathogens were retained in the top 30 mm of the sand. CONCLUSIONS: On the basis of the relative spatial distribution of trace organisms in the sand, we speculate that adsorption processes likely dominated attenuation of the viral pathogens, more so than physical straining effects. Further study is required to fully elucidate the removal mechanisms. SIGNIFICANCE AND IMPACT OF THE STUDY: To the best of our knowledge this is the first study of the effective microbial removal capacity of coral sand under unsaturated conditions. The work represents an initial exploratory step of developing some standardized design practice of on-site wastewater treatment systems in Kiribati, to offer enhanced protection of groundwater resources and reduce diarrhoeal disease.

Predicting groundwater redox status on a regional scale using linear discriminant analysis.

Reducing conditions are necessary for denitrification, thus the groundwater redox status can be used to identify subsurface zones where potentially significant nitrate reduction can occur. Groundwater chemistry in two contrasting regions of New Zealand was classified with respect to redox status and related to mappable factors, such as geology, topography and soil characteristics using discriminant analysis. Redox assignment was carried out for water sampled from 568 and 2223 wells in the Waikato and Canterbury regions, respectively. For the Waikato region 64% of wells sampled indicated oxic conditions in the water; 18% indicated reduced conditions and 18% had attributes indicating both reducing and oxic conditions termed "mixed". In Canterbury 84% of wells indicated oxic conditions; 10% were mixed; and only 5% indicated reduced conditions. The analysis was performed over three different well depths, <25m, 25 to 100 and >100m. For both regions, the percentage of oxidised groundwater decreased with increasing well depth. Linear discriminant analysis was used to develop models to differentiate between the three redox states. Models were derived for each depth and region using 67% of the data, and then subsequently validated on the remaining 33%. The average agreement between predicted and measured redox status was 63% and 70% for the Waikato and Canterbury regions, respectively. The models were incorporated into GIS and the prediction of redox status was extended over the whole region, excluding mountainous land. This knowledge improves spatial prediction of reduced groundwater zones, and therefore, when combined with groundwater flow paths, improves estimates of denitrification.

Prevalence and correlates of resistance training in a regional Australian population.

BACKGROUND: The core components of physical activity, cardiovascular endurance, muscular strength, balance and flexibility can provide many health benefits and potentially slow declines associated with aging. Aerobic exercise message to the public has been widely promoted by national health authorities, although the promotion of resistance training has received far less attention. OBJECTIVES: In this research, the prevalence of resistance training in a sample of adults living in regional Australia was primarily assessed. DESIGN: A computer-assisted telephone interview survey (n=1230) was conducted by the Population Research Laboratory at Central Queensland University on Queensland adults in October to November 2006. Respondents were asked to report the frequency with which they engaged in resistance training. PARTICIPANTS: Respondents were 18 years or older that could be contacted by direct-dialled, land-based telephone service. A telephone database using a computer program to select, with replacement, a simple random sample of phone numbers selected respondents. RESULTS: Almost 14% of the population did some form of gym-based resistance training in the week before the survey. There was a significant (p<0.05) reduction in participation levels with age. Participation was highest amongst the youngest 18-34-year-olds (23.8%), steadily declining with age to a low of 7% in the 55 years and older age group. There was no significant association between sexes and participation in resistance training. CONCLUSIONS: The findings underscore the need to increase overall education on the benefits of resistance training with an emphasis among targeted adult populations to increase participation in resistance training.

The effects of timing and application of vibration on muscular contractions.

BACKGROUND: The effect of vibration stimulation on muscular strength is an emerging field of research and very little comprehensive work has been conducted at this stage. HYPOTHESIS: There will be no effects of timing or application of vibration stimulation on muscular strength and activation across isometric, isokinetic and concentric isotonic contractions. METHODS: There were 28 recreational athletes who participated in this study. Their characteristics were: (mean +/- SD) age, 22.8 +/- 5.6 yr; height, 174.1 +/- 8.8 cm; and body mass, 78.0 +/- 13.6 kg. The vibration stimulation was delivered at 50.42 +/- 1.16 Hz with an acceleration of 13.24 +/- 0.18 ms(-2). RESULTS: A series of one-way ANOVAs revealed significant (p < 0.05) improvements of 14.7 +/- 2.9% and 15.3 +/- 3.1% above normal contraction levels for concentric isotonic strength during and after the vibration stimulation, respectively. No significant improvements in isometric and isokinetic strength were evident. Concurrent measurement of electromyography (EMG) presented significant improvements during stimulation of 30.1 +/- 14.6%, 43.0 +/- 13.0%, and 107.1 +/- 44.4% in mean activation of rectus femoris (RF) for the isometric, isokinetic, and concentric isotonic contractions, respectively. Synchronous collection of vibromyography (VMG) during stimulation displayed a significant decrease of -6.4 +/- 1.5%, -5.1 +/- 1.2%, and -4.1 +/- 1.7% in mean VMG activity of RF for the isometric, isokinetic, and concentric isotonic contractions, respectively. CONCLUSIONS: Significant improvements in muscular strength and activation for concentric isotonic contractions performed during an applied vibration suggest that the optimal timing of a vibratory stimulation would be while the participant is contracting isotonically. However, further research needs to be conducted to establish the exact mechanism behind these improvements.

Identifying bone mass and muscular changes.

The aim of this investigation was to examine the impact of a six-month high intensity strength-training program on lumbar bone mineral density (BMD), trunk and lower limb strength in a population of Australian women aged 50 years and over. A subject pool of 44 women were recruited and randomly allocated into either strength training (n = 19) or active control (n = 25) groups. All subjects trained twice weekly in either a 50 minute supervised strength training session that progressed from 60% one repetition maximum (1RM) to 90% 1RM or a 50 minute group walk session. Measurements included a lumbar (L2-L4) BMD scan: peak isokinetic trunk strength and a dynamic 1RM squat as a measure of lower body strength. No significant group differences in lumbar BMD were evident at the completion of training. However, a significant (p < 0.05) within group change was apparent for the active control group as lumbar BMD decreased 1.7% below baseline testing. A significant (p < 0.05) group difference was evident with the strength trained group increasing peak isokinetic trunk strength (19.3%) and 1RM squat strength (34.4%) above that of the active controls. It was concluded that strength training provides an effective means for increasing trunk and lower limb strength in women over 50 years. The impact of strength training on lumbar BMD was not conclusive in the present study.

1,1,1-trichloro-2,2-bis (p-chlorophenyl)-ethane (DDT) and reduced bone mineral density.

The organochlorine pesticide 1,1,1-trichloro-2,2-bis (p-chlorophenyl)-ethane (DDT), is a well-known and widely dispersed "environmental estrogen" (World Health Organization Criteria no. 9; Geneva, Switzerland [1979]). Kelce et al. (Nature, 1995; 375:581-85) recently identified the DDT metabolite, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), has also recently been identified as a potent androgen receptor antagonist. The authors examined the relationship between serum levels of DDE and bone mineral density in 68 sedentary women who reported adequate dietary intake of calcium. Reduced bone mineral density was correlated significantly with age (r = -.36, p = .004), as well as with increases in the log of DDE levels in serum (r = -.27, p = .03). The authors also used multiple-regression analysis to examine the influence of other predictor variables on the relationship between log DDE and bone mineral density. The strongest model (p = .002) included log DDE (p = .018), age (p = .002), and years on hormone replacement therapy (p = .10) as predictor variables, and this model afforded prediction of 21% of bone mineral density variation. These results suggest that past community exposures to DDT may be associated with reduced bone mineral density in women.

Kinanthropometric and physiological characteristics of outrigger canoe paddlers.

We describe the physiological characteristics of amateur outrigger canoe paddlers. Twenty-one paddlers (13 males, 8 females) were evaluated for body stature, aerobic power, muscular strength and endurance, peak paddle force, flexibility and 250 m sprint paddle performance at the end of the outrigging season. The mean variables (+/- s) for the males were: age 27 +/- 9 years, height 175 +/- 5 cm, body mass 80 +/- 5 kg, arm span 178 +/- 7 cm, sitting height 100 +/- 2 cm, aerobic power 3.0 +/- 0.4 l x min(-1), maximum bench press strength 85 +/- 19 kg, right peak paddle force 382 +/- 66 N and left peak paddle force 369 +/- 69 N. For the females, these were: age 26 +/- 6 years, height 168 +/- 5 cm, body mass 70 +/- 8 kg, arm span 170 +/- 5 cm, sitting height 97 +/- 3 cm, aerobic power 2.3 +/- 0.51 l x min(-1), maximum bench press strength 47 +/- 10 kg, right peak paddle force 252 +/- 63 N and left peak paddle force 257 +/- 60 N. Analysis of variance revealed differences (P < 0.05) between the dominant and non-dominant sides of the body for peak paddle force, isokinetic internal and external rotation, and flexion and extension torque of the shoulder joint. The outrigger canoe paddlers were generally within the range of scores found to describe participants of other water craft sports. Outrigger canoeists should be concerned with the muscular strength imbalances associated with paddling technique.

Effect of exercise intensity on bone density, strength, and calcium turnover in older women.

PURPOSE: This study examined the effects of 24 wk of high intensity strength training or low intensity walking on lumbar bone mineral density (BMD), muscular strength, and calcium turnover in Australian women either taking hormone replacement therapy (HRT) or not taking HRT. METHODS: A subject pool of 64 women between 45-65 yr and randomly allocated into weights (N = 21), walking (N = 20), weightsHRT (N = 14), and walkingHRT (N = 9) groups completed this study. All subjects trained twice weekly in either a 50-min walking or weight-training program (60-90% IRM). Measurements included maximal isometric knee strength, IRM bench press, IRM squat, isokinetic back strength, lumbar (L2-L4) BMD, serum osteocalcin, and urinary deoxypyridinoline crosslinks (Dpd). RESULTS: No significant group differences in BMD were evident at the completion of training. However, a significant (P < 0.05) within group change was apparent for the walking group since BMD decreased 1.3% below baseline testing. Osteocalcin levels increased significantly (P < 0.05) in the walking (22%) group. Maximal bench press and squat strength improved significantly (P < 0.05) in the weights (25.8% and 37.7%) and weightsHRT (25.4% and 35.7%) groups. The weights group also increased significantly (P < 0.05) in isokinetic back strength (22.2%). CONCLUSION: It was concluded that short-term high intensity resistance training provides an effective means for increasing muscular strength in women between 45 and 65 yr. The training effects on lumbar BMD were not apparent in the present study.

The relationship between dynamic, isokinetic and isometric strength and bone mineral density in a population of 45 to 65 year old women.

This study investigated the relationship between age, lumbar spine bone mineral density (LS BMD) and muscular strength of peri and postmenopausal women between 45 and 65 years either taking or not taking hormone replacement therapy (HRT). Ninety six women were tested for LS BMD (L2-L4), one repetition maximum (1RM) bench press and squat, maximal voluntary isometric contraction (MVC) of the knee extensors and peak torque of back extensor muscles at a speed of 30 degrees s(-1). Bone and strength data were analysed to evaluate the relationships in incrementing five year age groups and based on groups either taking or not taking HRT. ANOVA revealed significant differences in LS BMD between the 45-49 and 55-59 (F[3,92]=2.6411, p<0.05; -8%) age groups amounting to an annual bone loss of 0.8% for this Australian based population. Non significant LS BMD results were evident after controlling for the influence of age and menopausal status on the groups either taking or not taking HRT. Significant differences between the 45-49 and 60-64 (F[3,92]=2.7463, p<0.05) age groups for 1RM bench press and the 45-49 and 60-64, 50-54 and 60-64, and, 55-59 and 60-64 (F[3,92]=4.2816, p<0.05) age groups for 1RM squat amounting to an 18.8% and 37.5% loss of dynamic upper and lower body strength, respectively. Group correlation coefficients ranged between (r=-0.20 and -0.34, p<0.05) for LS BMD, strength and age. The conclusions demonstrate a concomitant decline in maximal muscle strength and bone density between women 45 and 65 years irrespective of HRT. These results also demonstrate a 50% greater decline in lower body strength compared to upper body strength between women 45 and 65 years.

Changes in muscle morphology, electromyographic activity, and force production characteristics during progressive strength training in young and older men.

Effects of a 10-week progressive strength training program composed of a mixture of exercises for increasing muscle mass, maximal peak force, and explosive strength (rapid force production) were examined in 8 young (YM) (29+/-5 yrs) and 10 old (OM) (61+/-4 yrs) men. Electromyographic activity, maximal bilateral isometric peak force, and maximal rate of force development (RFD) of the knee extensors, muscle cross-sectional area (CSA) of the quadriceps femoris (QF), muscle fiber proportion, and fiber areas of types I, IIa, IIb, and IIab of the vastus lateralis were evaluated. Maximal and explosive strength values remained unaltered in both groups during a 3-week control period with no training preceding the strength training. After the 10-week training period, maximal isometric peak force increased from 1311+/-123 N by 15.6% (p <.05) in YM and from 976+/-168 N by 16.5% (p <.01) in OM. The pretraining RFD values of 4049+/-791 N*s(-1) in YM and 2526+/-1197 N*s(-1) in OM remained unaltered. Both groups showed significant increases (p < .05) in the averaged maximum IEMGs of the vastus muscles. The CSA of the QF increased from 90.3+/-7.9 cm2 in YM by 12.2% (p <.05) and from 74.7+/-7.8 cm2 in OM by 8.5% (p <.001). No changes occurred in the muscle fiber distribution of type I during the training, whereas the proportion of subtype IIab increased from 2% to 6% (p < .05) in YM and that of type IIb decreased in both YM from 25% to 16% (p < .01) and in OM from 15% to 6% (p < .05). The mean fiber area of type I increased after the 10-week training in YM (p < .001) and OM (p < .05) as well as that of type IIa in both YM (p < .01) and OM (p < .01). The individual percentage values for type I fibers were inversely correlated with the individual changes recorded during the training in the muscle CSA of the QF (r=-.56, p < .05). The present results suggest that both neural adaptations and the capacity of the skeletal muscle to undergo training-induced hypertrophy even in older people explain the gains observed in maximal force in older men, while rapid force production capacity recorded during the isometric knee extension action remained unaltered during the present mixed strength training program.

Electrophoretic separation of myosin heavy chain isoforms in the human m. vastus lateralis: references to reproducibility and relationships with force, electromechanical delay, fibre conduction velocity, endurance and electromyography.

The aim of this investigation was to determine the relationship between muscle performance and the myosin heavy chain (MHC) composition and the reliability of electrophoretically determined MHC compositions. A total of thirty-one male subjects participated in the experiments. Maximal voluntary isometric contractions (MVC) of the knee extensors were performed at an arbitrary knee angle of 90 degrees and the following variables were recorded: maximal isometric force, muscle fibre conduction velocity (MFCV), electromechanical delay (EMD), maximal rate of force development (MRFD), median frequency of EMG (MF) and iEMG. Static isometric contractions of the knee extensors were held at an angle of 90 degrees using contractile forces of 10%, 50% and 100% MVC, respectively. These tests were conducted on separate days. Muscle biopsy samples were obtained from the left m. vastus lateralis before MVC and static endurance tests. MHC protein isoform differences were determined through sodium dodecyl-polyacrylamide gel electrophoresis (SDS-PAGE) followed by densitometric analysis. Type I-MHC compositions of the m. vastus lateralis ranged from 20-68% with a mean of 49 +/- 18%, mean type IIa-MHC and type IIb-MHC percentages were 35 +/- 16% and 16 +/- 10%, respectively. MHC compositions of duplicate biopsy samples were not significantly different from that of original samples. The coefficients of variation calculated for duplicate biopsy samples suggested reasonable reproducibility for MHC isoform differentiation for type I-MHC and type-II MHC composition (CV = 12.6%). Differentiation between type IIa-MHC and type IIb-MHC was not always clear using the densitometric traces. Subjects with higher percentages of type II-MHC displayed significantly faster MFCV (r = 0.67, P < 0.1), isometric force development (r = 0.68, P < 0.1) and shorter periods of EMD (r = -0.72, P < 0.05). There was also a tendency toward faster MRFD in these subjects although results did not reach significance. Endurance times for isometric contractions held at 10%, 50% and 100% MVC to exhaustion were not correlated with MHC composition. No relationships between II-MHC composition and MF or iEMG were observed. It was suggested that surface electromyographic recordings obtained during isometric MVC did not reflect underlying differences in muscle fibre composition.

Reliability of an electrophoretic and image processing analysis of human skeletal muscle taken from m. vastus lateralis.

The relative content of myosin heavy chain (MHC) isoforms IIb, IIa and I in human skeletal muscle taken from the m. vastus lateralis of 30 healthy male subjects was analysed using mini-gel electrophoresis. Repeated electrophoretic gels utilizing the same methods were produced for all subjects and the determination of MHC protein bands was performed using a digital scanner and National Institutes of Health (NIH) Image software and laser densitometry. A comparison between the NIH Image processing technique and laser densitometry revealed differences of 6.47%, 6.35% and 6.84% between these measurement techniques for MHC-IIb, -IIa and -I isoforms, respectively. The percentage technical error of measurement (TEM%) between electrophoretic gels was shown to be 19.1%, 17.8% and 14.2%, with regard to percentage of occurrence of MHC-IIb, -IIa and -I isoforms respectively. The variation in electrophoretic gel analyses was shown to be 5.7%, 7.3% and 5.5%, with regard to the percentage of MHC-IIb, -IIa and -I isoforms respectively. Intra-class correlations comparing NIH Image and laser densitometry produced r values in the range 0.38-0.63. Comparisons between and within gel analyses produced r values in the range 0.59-0.94 and 0.93-0.98, respectively. Analyses of variance revealed no significant differences (P < 0.05) between analysis techniques, between gels or within gels for the measurement of MHC-IIb, -IIa and -I isoforms. The inter-gel error between fibre subgroups was moderate for the two type-II MHC populations and less for type-I MHC; the intra-individual error in the measuring technique used for classifying the MHC-IIb, -IIa and -I protein bands was small. The results obtained in this investigation showed consistent trends which may reflect a false classification of the type-II MHC populations for the inter-gel and intra-individual analyses. The NIH Image software and digitizing process was shown to be a valid and reliable method for distinguishing between MHC protein bands of human skeletal tissue as separated by mini-gel electrophoretic techniques.

Myoelectric evidence of peripheral muscle fatigue during exercise in severe hypoxia: some references to m. vastus lateralis myosin heavy chain composition.

Integrated electromyography (iEMG) of the m. vastus lateralis was analysed during cycle ergometry in male subjects (n = 8). Two work trials were conducted, one under normoxia (N), the other under environmental normobaric hypoxia (EH in which the oxygen fraction in inspired gas = 0.116), each trial lasting 10 min. The absolute power output (180 W) was the same for both trials and was equivalent to 77 (4)% of maximum heart rate in trial N. Maximal voluntary isometric contractions were performed after each trial to assess changes in force, muscle fibre conduction velocity (MFCV), electromechanical delay (EMD), median frequency of EMG (MF) and maximal iEMG (iEMGmax). Biopsy samples of muscle were obtained from the m. vastus medialis before testing. Myosin heavy chain (MHC) differences were determined through sodium dodecyl-polyacrylamide gel electrophoresis followed by densitometric analysis. No differences in submaximal iEMG were observed between EH and N trials during the first minute of work. At the end of both work trials iEMG was significantly elevated compared with starting values, however the iEMG recorded in EH exceeded N values by 15%. At the end of the EH trials the following were observed: a decrease in isometric force, MFCV and MF with an increase in EMD and the iEMGmax/force ratio. The iEMGmax was unchanged. No differences in any of these variables were observed after the N trial. Mean (SD) lactate concentrations following EH and N trials were 9.2 (4.4) mmol x 1(-1) and 3.5 (1.1) mmol x 1(-1), respectively. Results indicate that an increased motor unit recruitment and rate coding was needed in EH to maintain the required power output. The increased motor unit recruitment and rate coding were associated with myoelectric evidence of "peripheral" muscle fatigue. Subjects with higher compositions of type II MHC accumulated more lactate and displayed greater reductions in MF and MFCV during fatigue.

Influence of load and stretch shortening cycle on the kinematics, kinetics and muscle activation that occurs during explosive upper-body movements.

Although explosive power in lower-body movements has been extensively studied, there is a paucity of research examining such movements in the upper body. This study aimed to investigate the influence of load and the stretch shortening cycle (SSC) on the kinematics, kinetics, and muscle activation that occurs during maximal effort throws. A total of 17 male subjects performed SSC and concentric only (CO) bench throws using loads of 15%, 30%, 45%, 60%, 75%, 90% and 100% of their previously determined one repetition maximum bench press. The displacement, velocity, acceleration, force and power output as well as the electromyogram (EMG) from pectoralis major, anterior deltoid, and triceps brachii were recorded for each throw. The results were compared using multivariate analysis of variance with repeated measures. A criterion alpha level of P < or = 0.05 was used. Similar force velocity power relationships were determined for this multijoint upper-body movement as has been found for isolated muscles, single joint movements, and vertical jumping. The highest power output was produced at the 30% [563 (104) W] and 45% [560 (86) W] loads during the SSC throws. Force output increased as a function of load; however, even the lighter loads resulted in considerable force due to the high accelerations produced. Average velocity, average and peak force, and average and peak power output were significantly higher for the SSC throws compared to the CO throws. However, peak velocity and height thrown were not potentiated by performing the pre-stretch because the duration and range of movement allowed the ability of the muscle to generate force at high shortening velocities to dominate the resulting throw. As such, explosive movements involving longer concentric actions than experienced during brief SSC movements may be limited by the ability of the muscle to produce force during fast contraction velocities.

The effect of a braking device in reducing the ground impact forces inherent in plyometric training.

As a consequence of performing plyometric type exercises, such as depth jumps, impact forces placed on the musculoskeletal system during landing can lead to a potential for injury. A reduction of impact forces upon landing could therefore contribute to reduce the risk of injury. Twenty subjects performed a series of loaded jumps for maximal height, with and without a brake mechanism designed to reduce impact force during landing. The braked jumps were performed on the Plyometric Power System (PPS) with its braking mechanism set at 75% of body weight during the downward phase. The non-braked condition involved jumps with no braking. Vertical ground reaction force data, sampled for 5.5 s at 550 Hz from a Kistler forceplate, were collected for each jump condition. The following parameters were then calculated: peak vertical force, time to peak force, passive impact impulse and maximum concentric force. The brake served to significantly (p < 0.01) reduce peak impact force by 155% and passive impact impulse by 200%. No significant differences were found for peak concentric force production. The braking mechanism of the PPS significantly reduced ground impact forces without impeding concentric force production. The reduction in eccentric loading, using the braking mechanism, may reduce the incidence of injury associated with landings from high intensity plyometric exercises.

The optimal training load for the development of dynamic athletic performance.

This study was performed to determine which of three theoretically optimal resistance training modalities resulted in the greatest enhancement in the performance of a series of dynamic athletic activities. The three training modalities included 1) traditional weight training, 2) plyometric training, and 3) explosive weight training at the load that maximized mechanical power output. Sixty-four previously trained subjects were randomly allocated to four groups that included the above three training modalities and a control group. The experimental groups trained for 10 wk performing either heavy squat lifts, depth jumps, or weighted squat jumps. All subjects were tested prior to training, after 5 wk of training and at the completion of the training period. The test items included 1) 30-m sprint, 2) vertical jumps performed with and without a countermovement, 3) maximal cycle test, 4) isokinetic leg extension test, and 5) a maximal isometric test. The experimental group which trained with the load that maximized mechanical power achieved the best overall results in enhancing dynamic athletic performance recording statistically significant (P < 0.05) improvements on most test items and producing statistically superior results to the two other training modalities on the jumping and isokinetic tests.

Major surgical intervention during extracorporeal membrane oxygenation.

Of 135 patients treated with extracorporeal membrane oxygenation (ECMO) between January 1987 and December 1989, 19 (14.0%) patients underwent surgical procedures while on ECMO. Thirteen (68%) patients had operations related to hemorrhage, including cannula site (6), mediastinal (1), hemoperitoneum (3), and hemothorax (3). Six of 13 patients required repetitive operations for bleeding; 4 of 6 died. Six (35%) patients had operations for congenital pathology including patent ductus (PDA) ligation (2), repair of transposition of the great vessels (2), repair of coarctation (1), and repair of congenital diaphragmatic hernia (3). One patient had multiple simultaneous procedures performed. Of these 6 patients, 4 were decannulated immediately and 2 were decannulated within 28 hours following surgery without any bleeding complications. Fifteen of 19 patients were operated on in the neonatal intensive care unit. The 4 remaining patients required transport on ECMO to the surgical suite. Thirteen of the 19 patients requiring surgical intervention on ECMO survived. In the 13 survivors, the mean time to decannulation postoperative was 45 hours, and in those that died it was 90 hours. Our experience suggests that surgical intervention while on ECMO is technically feasible with the best results achieved when rapid discontinuation of ECMO can be accomplished postoperatively. Due to this fact major surgical intervention should be postponed if possible until near the conclusion of the ECMO therapy.