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Success in sport can provide a source of national pride for a society, and vast financial and personal rewards for an individual athlete. It is therefore not surprising that many athletes will go to great lengths in pursuit of success. The provision of healthcare for elite sports people has the potential to create many ethical issues for sports doctors; however there has been little discussion of them to date. This study highlights these issues. Respondents to a questionnaire identified many ethical matters, common to other areas of medicine. However they also raised problems unique to sports medicine. Some of these ethical difficulties arise out of the place of the sports doctor within the hierarchy of sport. Yet others arise out of the special relationship between sports doctors and individual players/athletes. This study raises some important questions regarding the governance of healthcare in sport, and what support and guidance is available to sports doctors. As medical and scientific intervention in sport escalates, there is a risk that demands for enhanced performance may compromise the health of the athlete, and the role the sports doctor plays remains a critical question.

The objective of this study was to determine the effects of postmortem muscle pH and temperature declines on the actomyosin ATPase activity of muscle fibers expressing different MyHC isoforms. Using a quantitative histochemical procedure to determine ATPase activity, the maximum actomyosin ATPase activity was determined on individual fibers classified by MyHC expression. Samples were collected from the red (RST) and white (WST) semitendinosus muscles at 3 min and 24 h postmortem from electrically stimulated (ES) and control (NS) pork carcasses. In samples taken at 3 min postmortem, type I fibers had the lowest ATPase activity staining and type 2X and 2B had the highest activity staining, with type 2A fibers intermediate. Postmortem time and carcass treatment did not influence the ATPase activity staining of type I muscle fibers. ATPase activity staining of 2A fibers was lower (p<0.001) in 24 h samples than in 3 min samples from ES carcasses. In 3 min and NS-24 h samples, RST type 2A fibers had lower (p<0.05) activities than type 2A fibers from the WST. In type 2X fibers, ATPase activity staining decreased (p<0.01) from 3 min to 24 h postmortem in ES carcasses. This decrease was more severe in WST 2X fibers compared to RST 2X fibers. ATPase activity staining in type 2B fibers did not decrease from 3 min to 24 h postmortem in NS carcasses. In ES carcasses, activity staining of 2B fibers decreased (p<0.0001) with time postmortem. The results of the experiment indicate that fibers expressing fast MyHC isoforms have a higher ATPase activity early postmortem than slow muscle fibers but are more prone to inactivation by a rapid pH decline.

The pH and Ca(2+) sensitivity of myofibrillar ATPase activity plays an integral role in regulating postmortem muscle ATP utilization and likely paces postmortem glycolysis. The objective of this study was to determine the influence of pH and Ca(2+) concentration on the ATPase activity of myofibrils from red semitendinosus (RST) and white semitendinosus (WST) porcine muscles. Myofibrillar ATPase was measured at 39 °C over a pH range 5-7.5 and a [Ca(2+)] range pCa 4-9 (10(-4)-10(-9)M). At maximum Ca(2+)-dependent activation (pCa 4), RST myofibrils had lower (p<0.0001) ATPase activity than WST myofibrils. This maximum activity of myofibrils from both muscle regions was not influenced from pH 7.5 to 6.5, declined between pH 6.5 and 5.75 (Hill coefficient, n(H)=2.7-3.4; pH at half maximum activity, pH(50)=5.97) and was near zero at pH 5.5. At pH 7, pCa-activity relationships showed that RST required less Ca(2+) for half-maximum activation (higher pCa(50); 6.50) than WST myofibrils (pCa(50)=6.35) but had no difference in n(H). At pH 7, both RST and WST myofibrils had maximum Ca(2+)-dependent, actin-activated ATPase activity at pCa ⩽6 and Ca(2+)-independent myosin ATPase activity at pCa ⩾6.75. pCa-activity relationships at different pH levels indicated that pCa(50) decreased with pH from pH 6.5 to 6.125 in both RST and WST myofibrils. At pH <5.75, [Ca(2+)] did not influence ATPase activity in RST or WST myofibrils. These data show that myofibrils with predominantly fast MyHC (WST) have a higher actin-activated myosin ATPase activity than myofibrils with primarily slow MyHC isoforms (RST) at Ca(2+) concentrations and pH values characteristic of postmortem muscle.

The objective of this study was to determine the influence of myofibril isolation procedures and myosin heavy chain (MyHC) isoform composition on myofibrillar ATPase activity as related to postmortem muscle metabolism. Myofibrils from the red (RST) and white (WST) portions of semitendinosus muscles were isolated using two different methods (A and B) at 3 min and 24 h postmortem in control (NS) and electrically stimulated (ES) pork carcasses. Comparison of the relative MyHC isoform profiles between the two different myofibril isolation methods and myosin extracts from the RST and WST at 3 min showed that method B myofibrils were more similar to the myosin extract than method A. Myofibrillar ATPase activity remained constant or increased (P<0.01) from 3 min to 24 h postmortem in NS carcasses and decreased (P<0.0001) in ES carcasses. From the RST, method A myofibrils had higher (P<0.0001) ATPase activity compared to method B across sampling time and carcass treatment. In the WST, method A myofibrils had lower (P<0.01) activity at 3 min, were not different at 24 h in NS carcasses, but had higher (P<0.05) activity at 24 h in ES carcasses versus method B myofibrils. Compared to method B, isolation method A biased the isoform profile of myofibril samples more towards faster MyHC (2A and 2X) in the RST and towards MyHC 2X in the WST. Results suggest that the ATPase activity and MyHC isoform profile of isolated myofibril samples are influenced by method of myofibril isolation, postmortem sampling time, and the rate of postmortem metabolism. Thus, differences in MyHC isoform profile and method of myofibril isolation must be taken into account to determine accurately the relationship between myofibrillar ATPase activity and rate of postmortem metabolism.

The loss of normal weight-bearing activity, which occurs during bed rest, limb immobilization, and spaceflight, stimulates a catabolic response within the musculoskeletal system, which results in a loss of skeletal muscle mass and bone mineral. The mechanism by which loading of muscle and bone is sensed and translated into signals controlling tissue formation remains a major question in the field of musculoskeletal research. In this investigation, we have examined the ability of two potentially anti-atrophic proteins, IGF-I and Shh, to inhibit disuse atrophy within muscle and bone, when electroporated into skeletal muscle. We have found that electroporation and ectopic expression of IGF-I and/or Shh within the gastrocnemius/soleus muscle significantly stimulated muscle fiber hypertrophy and increases in muscle size. In addition, we report that electroporation and ectopic expression of IGF-I and/or Shh within the gastrocnemius/soleus muscle attenuated the lost of muscle fiber area, muscle mass, and muscle mass density that normally occurs during disuse muscle atrophy. Finally, we found that ectopic expression of IGF-I and Shh within the gastrocnemius/soleus muscle inhibits parameters of osteopenia within the tibia and fibula associated with hindlimb unloading. These results support the theory that skeletal muscle can regulate bone maintenance and could offer potentially novel and efficient therapeutic options for attenuating muscle and bone atrophy during aging, illness and spaceflight.

Color image features were computed to characterize the skeletal maturity of beef carcasses based on cartilage ossification in the thoracic vertebrae. A trained neural network was tested for predicting USDA beef maturity grades from image features of ossification. A feature curve was defined to characterize the color variations of an isolated cartilage-bone object. Both RGB and HSL color systems were used to derive image features. The maturity grades were assigned by an official USDA grader. Two sets of samples were obtained from two different meat-processing plants. The first set contained samples of only A and B maturity grades whereas the second set had all five maturity classifications (A through E). The hue value was the most useful color feature. The mean hue values of cartilage differed (P<0.05) among the maturity grades and the feature curve based on the hue value was used as neural network input for maturity prediction. The accuracy of prediction was 75% for the first set of samples and 65.9% for the second set of samples. The results data show the potential of computer vision techniques for beef maturity assessment.

Carcasses from 64 gilts were subjected to electrical stimulation (ES) at 3, 15, 25, 35, 45, and 55 min postmortem or were untreated (NS). Temperature and pH of longissimus muscles were recorded at 1, 7, 14, 20, 30, 40, 50, and 60 min, and 24 h postmortem. Muscle samples were collected at 1, 30 and 60 min, and 24 h for determining glycolytic metabolite concentrations. ES at 3, 15, and 25 min resulted in lower (P<0.05) muscle pH, but stimulation after 25 min had no effect on muscle pH. Likewise, ES prior to 25 min resulted in greater (P<0.05) muscle temperatures. Muscle lactate concentrations were greater (P<0.05) in carcasses stimulated before 45 min postmortem. Glucose 6-phosphate concentration decreased (P<0.05) during the first hr postmortem and increased (P<0.05) thereafter. ES of carcasses at 45 and 55 min resulted in higher (P<0.05) concentrations of muscle glucose 6-phosphate at 24 h compared with NS and early-stimulated carcasses. Muscle glycogen concentrations at 30 min in carcasses stimulated at 3, 15 and 25 min were lower (P<0.05) than NS carcasses. Carcasses stimulated at 3 and 15 min exhibited lower (P<0.05) concentrations of muscle glycogen at 60 min than NS carcasses. Carcasses stimulated at 3 and 15 min postmortem exhibited lower (P<0.05) color and firmness scores, while ES at 3 and 25 min postmortem resulted in lower (P<0.05) water holding capacity. ES had no significant effect on CIE L(∗), a(∗), b(∗), or 24 h muscle pH. These data show that ES of pork carcasses during the first 25 min postmortem creates PSE-like quality characteristics and suggest that ES is a potential model for studying pork quality development.

The objective of this study was to examine the effects of somatotropin (ST) on porcine reproductive and metabolic statuses during early pregnancy. Four pregnant crossbred gilts received 6 mg of recombinant porcine somatotropin (rpST) daily from days 10 to 27 after artificial insemination while six pregnant gilts served as controls. Blood samples were taken on days 8, 10, 12, 14, 18, 22, and 27 prior to rpST injections (8:00 h) and subsequently at 9:00, 10:00, 12:00, 14:00, 16:00, 18:00, and 20:00 h. On all remaining days of treatment, samples were taken once daily before injections (8:00 h). The samples were assayed for the metabolic hormones: ST, insulin-like growth factor I (IGF-I), insulin, thyroxine (T(4)), triiodothyronine (T(3)), and cortisol; for metabolites: free fatty acids (FFA) and glucose; and for the reproductive hormones: luteinizing hormone (LH), progesterone, estradiol-17beta, estrone sulfate, and prostaglandin F(2alpha). Delivery of rpST daily induced a 20- to 40-fold increase in plasma ST concentrations. Moreover, repeated administration of rpST resulted in a continuous increase in plasma IGF-I concentration (P < 0.001), from 191.0 +/- 22.3-340.0 +/- 15.3 ng/mL 24 h after initial injection to 591.3 +/- 46.8 ng/mL after final injections. Mean serum insulin tended to be greater in rpST-treated gilts. Blood concentrations of T(4) were reduced (P < 0.05) from day 14 of gestation in treated gilts while T(3) concentrations remained unchanged. Concentrations of both glucose and FFA were greater (P < 0.01) and cortisol concentrations were unchanged in treated gilts. Changes in reproductive steroid hormones were minimally affected. Circulating progesterone (P = 0.078), and estradiol-17beta (P = 0.087) concentrations tended to be lower in treated animals. These data show that treatment of pregnant gilts with rpST during early gestation mainly impacts metabolic rather than reproductive status., (Copyright 2002 Elsevier Science Inc.)

The objective of this study was to determine the impact of myosin heavy chain (MyHC) isoforms (I, IIB, IIA and IIX) on pork quality traits of halothane (HAL)-negative (NN) and halothane-carrier (Nn) pigs. Gilts (n=32) were assigned to a 2×2 factorial of genetic population (GP) and slaughter weight (WT; 120 and 135 kg). Classical meat quality characteristics were collected and MyHC content was determined on muscle samples. Regression equations for pork quality and carcass composition traits were determined. Only I/IIB accounted for variation in drip loss of NN gilts (R(2)=0.18), while GP related to drip loss in Nn gilts (R(2)=0.70). Type I MyHC content explained variation in ultimate (24 h) muscle pH of NN gilts (R(2)=0.09), while I/IIB, I/IIX and IIB/IIX were significant for Nn gilts (R(2)=0.99). I/IIA, I/IIX, IIB/IIX and GP accounted for variation in Hunter Color a (redness) values of NN gilts (R(2)=0.69), while IIB, IIA, IIB/IIA and GP were significant for Nn gilts (R(2)=0.97). Overall, fiber type composition accounts for a larger proportion of variation in the quality traits of Nn compared to NN gilts.

Background: There is some evidence that patients with renal failure who have arterial procedures may have a poor outcome. This study compared the hospital mortality rate of arterial surgery in patients with chronic renal failure and those with normal renal function., Methods: A consecutive series of 1718 patients undergoing arterial reconstructive surgery (excluding amputation) was entered prospectively on to a computerized database. Chronic renal failure was defined as a serum creatinine level over 400 micromol/l, or dialysis (either peritoneal or haemodialysis), or a successful renal transplant. Mortality was assessed at 30 days or in hospital., Results: There were 69 patients (4.0 per cent) who were defined as having chronic renal failure. The mortality rate in this group was 23 per cent (16 patients) compared with 7.3 per cent (120 patients) of the 1649 patients without renal failure. The mortality rate was highest in patients undergoing urgent or emergency surgery and in those undergoing reconstruction for lower limb occlusive disease. The main causes of death were related to the cardiovascular system., Conclusion: Patients with chronic renal failure undergoing arterial surgery have a poor outcome compared with those with normal renal function.

Currently, fresh pork color is visually evaluated using either the Japanese Pork Color Standards (JPCS) or the National Pork Producers Council Pork Quality Standards (NPPC) as a reference. Although useful, visual evaluation of meat color can vary with evaluator and may be quite expensive. In this study, three separate studies were used to compare the ability of color machine vision (CMV) and untrained panelists to evaluate pork color. Panels visually evaluated over 200 pork loin chops using either the JPCS or NPPC reference standards. Results from each panel were used to evaluate the ability of the CMV to sort pork loin chops based on the same criteria. Representative samples, typical of each color class, were used to train neural-network-based image processing software. After training, the CMV system was used to evaluate quality classes of pork samples based on color distribution. Classification by CMV was compared with the average panel score, rounded to the nearest integer. Training the CMV system using images of actual meat samples resulted in a stronger correlation to panel scores than training with either set of artificial color standards. Agreement between the CMV system and the panels was as high as 90%. Agreement between individual panelists and the integer panel average (52 to 85%) was less than that observed for CMV classification. Finally, the on-line performance of CMV using a laboratory conveyor system was simulated by repeatedly classifying 37 samples at a speed of 1 sample per second. Collectively, these results demonstrate that CMV is a rapid and repeatable means of evaluating pork color.

A detailed methodology is described for fluorescence-activated cell sorting (FACS) of porcine muscle cells that have been transfected to express green fluorescent protein (GFP). Cells are liberated from porcine skeletal muscle and primary cultures are transfected with DNA encoding GFP. Primary cultures are subjected to immunocytochemistry using a primary muscle-specific monoclonal antibody followed by incubation with a phycoerythrin-conjugated second antibody. Transfected myoblasts are sorted from fibroblasts using forward angle light scatter and ninety degree light scatter, phycoerythrin fluorescence, and GFP fluorescence. These procedures allow for isolation of genetically- engineered porcine muscle cells more rapidly than traditional clonal selection procedures. Consequently, FACS provides porcine myoblast populations that retain the majority of their replicative capacity and are not contaminated with non-myogenic cells.

The objective of this study was to determine if electrical stimulation (ES) early postmortem is an effective method to generate PSE-like meat. One hundred and thirty-eight gilts (85-125 kg) from heavy muscled (HM), normal muscled (NM), and light muscled (LM) porcine genetic lines were subjected to one of two treatments: ES (26 pulses of 500 V, 60 Hz) at 3 min postmortem or non-stimulated (NS). Pigs from HM line were further characterized as halothane (HAL) carriers (Nn) or non-carriers (NN). ES carcasses had lower (P<0.0001) pH values and higher (P<0.0001) temperature than NS carcasses during the first 56 min postmortem. ES carcasses had lower (P<0.0001) a*-values, and color and firmness scores, as well as higher (P<0.0001) drip loss and L*-values. No significant interactions were found between treatment and genetic line or HAL gene status with regard to pH, temperature, or quality characteristics. Temperature and pH declines within the first hour postmortem were not affected by genetic line, but slight (P<0.01) quality differences were observed. Nn and NN did not differ in pH or temperature within the first hour postmortem, but Nn carcasses had lower (P<0.01) color and firmness scores, and higher (P<0.05) drip loss. These results show that ES early postmortem is an effective method for simulating PSE development in pigs of different muscling and HAL gene status, and suggest that pH and temperature decline alone cannot explain all aspects of pork quality.

Open water swimming is a rapidly growing discipline within organized aquatic sport. Although endurance swimmers have been challenged by oceans, rivers, and lakes for many years, the real understanding of the science of the sport is a new development. Similarly, the clinical problems of long-distance swimming in frequently inhospitable environments now are recognized and managed more effectively. At all times, the health and safety of athletes remain our shared, prime concerns.

The independent effects of decreased food intake and diabetic hyperglycemia on serum GH, serum IGF-I and tissue IGF-I expression were examined in young streptozotocin-diabetic pigs. Each of three treatments (control, diabetic, and insulin-treated diabetic) were represented within three levels of regulated food intake (FI) provided as three meals per day equivalent to 100, 50, and 10% of the voluntary FI consumed by the untreated diabetics. Reduction of food intake was associated with decreased body weight gains, decreased serum IGF-I concentrations, and increased serum GH concentrations. Nutrient restriction also tended to decrease the relative abundance of IGF-I mRNA in liver and skeletal muscle. Diabetic pigs with hyperglycemia and hypoinsulinemia had higher serum concentrations of IGF-I than pair-fed controls, but exogenous insulin treatment of these diabetic pigs increased serum IGF-I even further and also tended to increase the relative abundance of IGF-I mRNA in liver and skeletal muscle. When the statistical effects of reduced FI were eliminated, neither the present form of diabetes nor exogenous insulin affected serum GH. In summary, diabetes-induced changes in IGF-I in these pigs depended primarily on the reduced level of food intake occurring in these hypoinsulinemic, hyperglycemic subjects.

Rugby football is associated with a number of biomechanical stresses which are frequently associated with knee injury. Consequently, there has been a significant interest within the game regarding the techniques of knee surgery and accelerated rehabilitation and the prophylactic use of external knee support. Knee bracing and strapping techniques are widely practised by rugby players but their results vary and there are mixed opinions over their usefulness. This article discusses the current trends in external knee support, draws on the experiences of other professional football codes and extrapolates these to the rugby union setting. Widespread opinion confirms that improper or incomplete rehabilitation is linked to re-injury. There is also a general acceptance that external support for the knee in sport should never be used to mask an injury. There is no evidence that the prophylactic taping of the knee joint provides any significant external stabilisation for more than the first few minutes of play. This lack of lasting stabilisation is due to the vigorous physical activity associated with rugby which results in a rapid loss of the custom fit of the external support to the profile of the joint. The taping the patella to reduce the pain associated with poor patellar alignment is considered to be effective; however, the correction of other biomechanical influences is also important. Adhesive tape, when applied correctly, will reposition the patella but this technique is limited by factors such as sweating and movement. A number of knee braces are currently available and these are classified according to their prophylactic, rehabilitative or functional design. In this article, their use in rugby applies to external support as an aid to rehabilitation rather than injury prevention.

In any contact sport where impact and collision are an accepted feature, the use of various forms of external padding has become more common. Rugby union players experience a combination of characteristic extrinsic forces through the acts of tackling and scrummaging. The laws which are part of the international regulation of rugby union only permit the wearing of certain, clearly delineated forms of padding. Only then is such padding permitted on medical recommendation, provided that this padding is attached to the body or sewn into the jersey. This article discusses the padding of the shoulders, shins and thighs of rugby union players and highlights the need to address these issues with respect to the increasing number of women who are now playing this sport, particularly in the Southern hemisphere. There is little evidence to show that shoulder pads decrease the incidence of severe shoulder injuries. However, well-fitting shoulder pads constructed of materials that effectively disperse the force of impact appear to reduce the effect of direct contact and reduce the potential for soft tissue damage. Shin guards that are made of light, soft, compliant materials are effective in reducing impact to the shin and thereby reduce the risk of bruising injuries which are common to the pretibial region. Similarly, thigh pads are considered to be able to modify the effects of direct contact forces to the anterior thigh where deep contusional injuries with the potential for myositis ossificans are well reported. Informed advice for women rugby players regarding the use of specific padding is unavailable at present. Current information is anecdotal and not confirmed by statistical studies or well-conducted research. In these circumstances, women rugby players should observe the same recommendations that apply to their male counterparts.

Ankle inversion sprain is common in rugby. This review outlines research evidence relating to the effects of external ankle support by means of bracing and taping, on the incidence of ankle injuries, how performance is affected by support, how support may act at the joint (with respect to end range of motion, strength, resistive torque, muscle activation patterns and proprioception) to prevent injury, and how exercise changes the effectiveness of support. In addition, the implications of the laws of rugby for the use of external support are discussed. Prospective epidemiological studies have shown a decrease in the incidence of ankle injury with external ankle support use. The effectiveness of external ankle support was dependent upon the material properties and application method of the tape or brace, and on the athlete's status of ankle stability or previous injury. Experimental studies have indicated that the degree of ankle inversion restriction provided, and the degree of loss of restriction after exercise, were dependent upon the external support tested. External ankle support has been reported to have no effect on performance, or to have an adverse effect on performance in a variety of movement tasks. No prophylactic external ankle support has been shown to improve performance. If an external support is to provide mechanical support to a ligament it should exceed the strength of the ligament, which for the anterior fibular ligament is a force limit of between 6 and 56 kg. Tape can provide only limited mechanical support of the ankle joint complex, but it may have proprioceptive effects. Taping may work as a psychological reminder, so that the athlete consciously moderates lower limb-loading behaviour. There is equivocal evidence of the effect of brace use on ground reaction force excursions, balance ability and ankle strength. It is concluded that while there have been many investigations of the effects of tape and some forms of brace on ankle range of motion with and without exercise, there is equivocal evidence regarding the mechanism by which an external support acts. It is recommended that future research address the effects of external ankle support during dynamic exercise and that brace manufacturers utilise the information in the development of future brace designs to help reduce the risk of ankle inversion sprain injury. As external support can decrease the incidence of ankle inversion sprain the International Rugby Board should consider the use of ankle braces in rugby, allowing for stiff lateral components of the brace.

Transcriptional regulation of the porcine alpha-skeletal actin gene was investigated by comparative transient transfection assays in cultured mammalian cells and by direct DNA injection in skeletal muscle. Intron I sequences were necessary to direct high-level, cell-specific porcine alpha-skeletal actin expression in C2C12 myotubes, but they inhibited transcription in skeletal muscle. A 5' distal sequence (-1929 to -550), had enhancer-like activity in C2C12 myotubes and directly injected muscle, and inhibited transcription in Hela cells. In contrast, a central region (-550 to -388) enhanced basal transcription in directly injected muscle, but not in C2C12 myotubes. A distal regulatory element localized to the 3' untranslated region modulated SV40 promoter activity only in cell culture studies. These results suggest that the intragenic and 3' distal regulatory element may be differentially utilized during differentiation and maturation of skeletal muscle. All three regions decreased SV40 promoter activity in Hela cells, suggesting that they play a role in defining tissue-specific expression of porcine alpha-skeletal actin. Furthermore, different regulatory programs of alpha-skeletal actin expression appear to exist in these two experimental systems.

Unlike the random distribution of fiber types seen in skeletal muscles of most mammals, pig muscle exhibits a rosette pattern consisting of islets of slow fibers surrounded by concentric circles of type IIA and IIB fibers. Within each islet of slow fibers, one of the central fibers is a primary myofiber, whereas all others are secondary fibers. The present study demonstrates that a subpopulation of the slow secondary fibers transiently expresses alpha-myosin heavy chain (MHC). Two cDNA libraries were made from longissimus dorsi skeletal muscle of 14-day-old piglet and adult pig atrium; the latter muscle is mainly composed of alpha-MHC. Screening of the libraries with a human anti-alpha-MHC mAb (F8812F8) demonstrated the presence of positive MHC clones in both libraries; the nucleotide sequence of the 3'-untranslated region (3'-UTR) was identical in both libraries. As this MHC 3'-UTR had 75% homology with the human alpha-MHC, it was identified as pig alpha-MHC. Using specific cRNA probes and mAbs against pig alpha-cardiac and beta/slow/type I MHC, we studied the expression of these MHCs in developing pig semitendinosus muscle by combining in situ hybridization and immunocytochemistry on serial sections at 90 days of gestation, and at 1, 6, 35 days and 6 months of age. The results showed that a subpopulation of secondary fibers that directly abut primary fibers, transiently produced alpha-MHC, both at the levels of the protein and its transcript. Subsequently, these fibres expressed beta-MHC. At 1 day, immunocytochemistry showed that 16% of the secondary fibers expressed alpha-MHC, among which 20% did not yet express beta-MHC. At 6 days, alpha- and beta-MHCs were mostly present in the same fibers, i.e., 23% of the secondary fibers. Thereafter, the proportion of secondary fibers reacting with alpha-MHC mAb decreased to 10% at 5 weeks and 0% at 6 months, whereas beta-MHC was still accumulating in about 38% of the secondary fibers. During the period studied, the distribution of alpha- and beta-MHC transcripts closely matched that of the corresponding proteins. Expression of alpha-MHC was not detected in primary type I muscle fibers and slow type I secondary fibers at the periphery of the rosettes of slow fibers. This study is the first unequivocal demonstration of a transitory expression of alpha-MHC in a subpopulation of secondary fibers in a limb skeletal muscle during mammalian development.

Nonsteroidal anti-inflammatory drugs (NSAID) are frequently used in sports medicine but few studies have documented their potential importance in modifying exercise-induced changes in renal function. The effects of indomethacin (50 mg orally every 8 h for 36 h) on renal blood flow (RBF) and glomerular filtration rate (GFR) were investigated in eight fit healthy males (age 21-42) before and after 30-min treadmill exercise at 80% VO2max and during 120-min recovery. Each volunteer served as their own control. There were no differences between control and indomethacin for the resting values of RBF, GFR, or renal vascular resistance (RVR). Using analysis of variance for repeated measures, indomethacin produced a significant reduction in RBF compared with control (P = 0.009) that was associated with a significant elevation in RVR (P = 0.027). Changes in GFR mirrored the changes in RBF but differences failed to reach statistical significance. These results suggest that with sustained exercise indomethacin can compromise renal function and potentiate the risk of developing acute renal failure. Indomethacin and other NSAID are widely used in the sports arena, and athletes should be warned of the potential danger of their use when renal function may be compromised.

A study of the prevalence of gastrointestinal symptoms during exercise was carried out on athletes who participated in the recent Enduro event in Dunedin. Of 119 competitors, 70 (59%) responded to our questionnaire and demonstrated a prevalence of gastrointestinal symptoms of 81%. Upper gastrointestinal symptoms were noticed in 58% with lower gastrointestinal symptoms, tending to be more severe and significant to the athlete, noticed in 61%. Speculations on the aetiology of these symptoms are included. The demonstrated high prevalence of symptoms during exercise and the relative lack of knowledge in this area provides a fertile ground for further objective research.

A generalized mathematical technique is presented for computing the elapsed time necessary for a lithium iodine powered pacemaker to reach any specified battery voltage or degree of battery discharge within its life span. In particular, the method yields a direct mathematical expression for the longevity of pacemakers the circuits of which possess linear load lines. Because the current-voltage relationship, which defines the load line, is affected by programmed output settings, electrode/tissue interface impedance and degree of inhibition, the method enables the direct determination of the effect of these parameters on pacemaker longevity.

It has been thought that upper intestinal symptoms of heartburn, regurgitation, belching, and chest pain experienced during exercise may represent esophageal dysfunction. The aim of this study is to examine esophageal function during moderate exercise in asymptomatic healthy athletes. Six healthy male athletes were exercised for 2 h on a treadmill set at a workload of 50% of their maximum oxygen uptake. Esophageal motility studies were performed immediately before, immediately after, and 1 h after the exercise. The mean lower esophageal sphincter pressure increased from a base line of 24 to 32 mm Hg immediately postexercise (p less than .01), reducing to 27 mm Hg after 1 hour rest. The mean amplitude and duration of esophageal peristalsis remained unchanged throughout the study. The significance of the lower esophageal sphincter pressure increase with moderate exercise is unknown but may relate to the observed exercise-induced increase in serum motilin, gastrin, and catecholamines.