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Musculoskeletal injury review in the U.S. space program.

Astronauts in NASA's space program are expected to remain fit to complete their on-orbit tasks and to function effectively in the event of contingency operations. Due to the generally self-directed exercise program and reliance on competitive sports and running for conditioning, plus limited emphasis on training techniques and rehabilitation, there have been a surprising number of orthopedic injuries and surgeries in this small adult population. This article examines the orthopedic injury history of U.S. astronauts during the period from 1987-95. The type of injury, activity involved, and subsequent surgical interventions are cataloged. There were a total of 26 fractures, 36 serious ligament, cartilage, or soft tissue injuries, and 28 orthopedic surgical procedures in this adult group with a mean astronaut corps size of only 94. Women accounted for 16% of the study population but accounted for only 1 of 28 surgical procedures. Knee injuries required surgical intervention 19 times. Running, skiing, and basketball were most frequently associated with injuries. The descriptive data regarding frequency of adverse events and activity associated with injuries is presented. These injury patterns are analyzed and suggestions made for future improvement, including decreased reliance on running and competitive athletics for conditioning, improved personal fitness training preflight, and coordinated rehabilitation postflight. Also recommended is the use of a lap pool for preflight total body fitness training, since swimming provides conditioning to those muscle groups used during spaceflight, and for variably weighted gravity rehabilitation postflight.

Adult↗

Economy during a simulated laboratory test triathlon is highly related to Olympic distance triathlon.

This study examined the relationship between Olympic distance triathlon (swim over 1.5 km, cycle over 40.0 km, and run over 10.0 km) and economy during a simulated laboratory test triathlon. Seventeen male triathletes conducted both maximal exercise tests and simulated laboratory triathlon. The latter test consisted of swimming (S), cycling (C) and running (R) stages as a continuous task using a flume-pool, a cycle ergometer and a treadmill, respectively. The exercise intensity and duration were 60% of VO2max during swimming, cycling and running for 30, 75 and 45 min, respectively. The index of economy was determined by the % VO2max at the last min of each stage during a simulated laboratory test triathlon. Results indicated that Olympic distance triathlon (total time) was correlated to swimming-VO2max (r = -0.621, p < 0.001), cycling-VO2max (r = -0.873, p < 0.001), running-VO2max (r = -0.891, p < 0.001), S-Economy (r = 0.208, ns), C-Economy (r = 0.601, p < 0.001) and R-Economy (r = 0.769, p < 0.001). There were also significant correlations between swimming time and swimming-VO2max (r = -0.648, p < 0.01), between cycling time and cycling-VO2max (r = -0.819, p <0.001), between running time and running-VO2max (r = -0.726, p < 0.001), between swimming time and S-Economy (r = 0.550, p < 0.05), between cycling time and C-Economy (r = 0.613, p < 0.01), and between running time and R-Economy (r = 0.548, p < 0.05). These results demonstrated that the larger VO2max during maximal exercise tests and smaller increment of VO2 during a simulated laboratory test triathlon indicating good economy were good predictors to determine the Olympic distance triathlon.

Adult↗

Detailed behavioral analysis reveals both task strategies and spatial memory impairments in rats given bilateral middle cerebral artery stroke.

Middle cerebral artery occlusion (MCAO) impairs performance in the water maze task by rats. The purpose was to evaluate the effect of bilateral MCAO in naive and strategies-pretrained rats using a detailed behavioral analysis to further develop a water maze model of stroke. Rats were trained in either a simple swim-to-visible platform task or in a conventional spatial version with a hidden platform in the pool. In the visible platform task naive stroked rats were impaired because of a marked tendency to swim thigmotaxically on most trials. For the spatial learning experiment, some rats received Morris' water maze strategies pretraining prior to MCAO and subsequent spatial training to familiarize them with the general behavioral strategies required in the task. In the spatial learning task naive stroked rats had both strategies and spatial learning impairments but pretrained stroked rats were indistinguishable from sham controls on all behavioral measures. All stroked rats had comparable bilateral brain damage measured using a computerized volumetric measuring technique. These results indicate that in naive rats bilateral MCAO causes behavioral strategies impairments in the visible and hidden platform versions of the water maze as well as specific spatial learning impairments in the hidden platform version. The results also indicate that behavioral strategies pretraining allows stroked rats to acquire and remember sufficient strategies skills and spatial information to perform as well as sham controls during subsequent spatial training. These techniques appear to be capable of quantifying the effects of potentially protective treatments for stroke.

Adaptation, Psychological↗

Wrist stabilisation and forearm muscle coactivation during freestyle swimming.

The aim of this study was to evaluate the stabilisation of the wrist joint and the ad hoc wrist muscles activations during the two principal phases of the freestyle stroke. Seven male international swimmers performed a maximal semi-tethered power test. A swimming ergometer fixed on the start area of the pool was used to collect maximal power. The electromyography signal (EMG) of the right flexor carpi ulnaris (FCU) and extensor carpi ulnaris (ECU) was recorded with surface electrodes and processed using the integrated EMG (IEMG). Frontal and sagittal video views were digitised frame by frame to determine the wrist angle in the sagittal plane and the principal phases of the stroke (insweep, outsweep). Important stabilisation of the wrist and high antagonist muscle activity were observed during the insweep phase due to the great mechanical constraints. In outsweep, less stabilisation and lower antagonist activities were noted. Factors affecting coactivations in elementary movements, e.g. intensity and instability of the load, accuracy and economy of the movement were confirmed in complex aquatic movement.

Adult↗

Accuracy of sperm-cervical mucus penetration tests in evaluating sperm motility in semen: a systematic quantitative review.

BACKGROUND: Our objective was to determine the accuracy of in-vitro sperm penetration into cervical mucus or substitutes in evaluating sperm motility in semen. METHODS: This was a systematic quantitative review of test accuracy studies. The Cochrane library (2000:4), Medline (1966-2001), Embase (1988-2001) and SciSearch (1981-2001) were searched, in addition to manual searches of conference papers and bibliographies of known primary and review articles. Primary studies measuring in-vitro sperm penetration into cervical mucus, or substitutes (i.e. sperm-mucus penetration test, SMPT) and comparing results with sperm motility in semen were included. RESULTS: There were 18 primary diagnostic studies published in 17 papers, involving a total of 2580 samples. Fourteen primary diagnostic tests used vanguard distance as diagnostic criteria (SMPT(vd)) and the pooled likelihood ratio (LR) for positive (LR+) and negative (LR-) tests were 2.29 (1.82-2.87) and 0.52 (0.44-0.63) respectively. Four studies used diagnostic criteria based directly or indirectly on swim-up sperm count per high power field (SMPT(sc)) instead. Their pooled LR+ and LR- were 5.24 (3.36-8.18) and 0.15 (0.06-0.39) respectively. CONCLUSIONS: SMPT(vd) has a low accuracy in the evaluation of sperm motility in semen. However, SMPT(sc) was found to be more accurate. This method of using sperm concentration, instead of vanguard distance, as diagnostic criteria of in-vitro SMPT has potential as a useful laboratory-based sperm function test.

Cervix Mucus↗

Evaluation of fins used in underwater swimming.

Underwater swimmers use fins which augment thrust to overcome drag and propel the diver. The VdotO2 of swimming as a function of speed, velocity as a function of kick frequency, maximal speed (v), maximal oxygen consumption (VdotO2) and the maximal thrust were determined for eight fins in 10 male divers swimming at 1.25 m depth in a 60 m annular pool. A theoretical analysis of fin cycles was also performed. VdotO2 increased as a second order polynomial as a function of velocity; VdotO2 = 0.045 + 1.65B V + 1.66 (2) V2 (r2 = 0.997), VdotO2 = 0.25 + 1.03 V + 1.83 V2 (r2 = 0.997) and VdotO2 = -0.15 + 2.26 V + 1.49 V2 (r2 = 0.997), for least, average and most economical fins respectively. Kick frequency increased linearly with velocity and had a unique movement path (signature), giving theoretical values that agreed with the measured thrust, drag and efficiency. In conclusion, virtually all thrust comes from the downward power stroke, with rigid fins kicked deep (high drag), while flexible fins are kicked less deep but with higher frequency (low efficiency). Kick depth and frequency explain the performance of the eight tested fins, and should be optimized to enhance diver performance.

Adult↗

Underwater fin swimming in women with reference to fin selection.

Underwater swimmers use fins, which provide thrust to overcome drag and propel the diver. The type of fin used has been shown to affect diver performance, however data are lacking for women. The oxygen consumption (VdotO2) of swimming as a function of speed, velocity as a function of kick frequency, maximal speed (v), maximal VdotO2 and the maximal thrust were determined for 8 female divers swimming at 1.25 m depth in a 60 m annular pool. VdotO2 increased as a function of v as; 0.52 + -0.485 V + 2.85 V2 (r2 = 0.996) and 0.12 + 1.52 V +1.275 V2 (r2 = 0.999) for high (5 fins) and low (3 fins) groupings, respectively. Splits, vents and flanges did not significantly affect VdotO2. Kick frequency increased linearly with v, with unique slopes for each fin. Maximal VdotO2 was not affect by fin type (1.46 +/- 0.05 l/min). Velocities that could be stained aerobically were 0.60 +/- 0.02 m/sec on average, with the most flexible fin higher (0.71 m/sec). Maximal v averaged 0.87 +/- 0.03 m/sec, with the most rigid fin lower (0.77 m/sec). Maximal thrust was not affected by fin and averaged 104 +/- 9 N. It can be concluded that female divers preferred the most flexible fins, which were also the most economical. This is most likely due to low leg power, which could also explain the absence of differences in maximal thrust and velocity.

Adult↗

Aerobic exercise in water versus walking on land: effects on indices of fat reduction and weight loss of obese women.

AIM: It has been suggested, that water exercise is less effective than weight-bearing exercise on land for body fat reduction. METHODS: To test this hypothesis 38 middle-aged obese women (25-47% body fat) participated in a 13 week exercise-diet program to compare the effects of aerobic exercise in water versus walking on land on indices of fat reduction and weight loss changes. Subjects were randomly assigned to 1 of 3 exercise groups: 1) walking on land (WL), 2) swimming (SW) at 27 degrees C water temperature and 3) walking in 29 degrees C water (WW) at the shallow end of a declining pool with the water at navel height. Subjects in the SW group alternated breast-, side-, and backstroke swimming without face immersion. Exercise parameters were kept constant for all three groups. Subjects participated in supervised exercise sessions for 40 min, 4 times a week at 70% of age-predicted maximum heart rate. Subjects were tested before and after the 13-week experimental period. RESULTS: Significant reductions in body weight, (5.9 kg), percent body fat, (3.7%), and skinfold and girth measurements, occurred in all groups. There where no significant differences between groups. CONCLUSIONS: The results of this study indicate that there are no differences in the effect of aerobic activities in the water versus weight-bearing aerobic exercise on land on body composition components as long as similar intensity, duration and frequency are used.

Adult↗

An improved Morris Water Maze tracking algorithm for psychophysiological studies--Part 2.

We have improved on an algorithm to track a rat swimming in a Morris Water Maze. The system is automatically configured to any pool and relative suitable light conditions. It tracks the rat's position and pose 10 times per second. The output data is displayed in a bitmap and also in a text file. The system was tested with an X-Y plotter using a simulated rat swimming in the maze. Known signals were provided to the rat and compared to the position and pose information provided by tracking algorithm.

Algorithms↗

The spatial-temporal and coordinative structures in elite male 100-m front crawl swimmers.

This study analysed the spatial-temporal and coordinative structures in 12 elite male 100-m front crawl swimmers. Swim performance was analysed over each length of a 25-m pool divided into five zones of 5 m. Velocity (V), stroke rate (SR), and stroke length (SL) were calculated for each zone and each length. Four stroke phases were identified by video analysis and the Index of Coordination (IdC) was established. Three modes of coordination were identified: catch-up (IdC < 0), opposition (IdC = 0), and superposition (IdC > 0). The swimmers tended to reduce the decrease in V and SR over the course of the 100 m by maintaining a stable SL. In fact, these spatial-temporal values were stable during the time spent stroking and were higher or lower during the start, the turns (in and out), and the finish. Thus the spatial-temporal changes did not occur within the lengths, but between them. Conversely, the evolution in the IdC showed that the swimmers had to install the stroke at the beginning and only reached a stable coordination in the second part of the race. Moreover, the IdC increased throughout the different zones of each 25-m length, indicating changes in motor organisation, particularly increases in the push or pull phases. The IdC values corresponded to a superposition of the arms, linked to a six-beat leg kick. Achievement of an effective superposition coordination occurred by boosting the stroke just after the turn-out until the end of the length. Regarding the spatial-temporal and coordinative structures of a 100-m front crawl, great swimming skill was reflected by both high and stable data.

Adult↗

Repeated spatial acquisition: effects of NMDA antagonists and morphine.

Effects of morphine and 2 N-methyl-D-aspartate (NMDA) receptor antagonists, phencyclidine and LY235959, were studied using a within-subject, repeated-acquisition/performance procedure adapted to the Morris Swim Task. In the performance component, subjects swam to a hidden platform that was always in the same location in the pool. In the acquisition component, the platform was moved to a different place for each session. Baseline training produced rapid and direct swims to the platform in the performance component and steep within-session learning curves in the acquisition component. All 3 compounds increased swim distances, escape latencies, and slowed swim speed in a dose-dependent manner, but only morphine consistently produced selective impairments on acquisition. NMDA antagonists generally affected acquisition only at doses that also disrupted performance, although phencyclidine produced selective effects in some animals. These outcomes were different than those from studies of response chains in primates, suggesting that task and species variables may be important determinants of drug effects on acquisition.

Analgesics, Opioid↗

Activity of fin muscles and fin motoneurons during swimming motor pattern in the lamprey.

Coordination of motoneuron activity is a fundamental prerequisite for the generation of functional locomotor patterns. We investigate the neural mechanisms that coordinate activity of motoneuron pools in the vertebrate spinal cord with differing phases of activity in the locomotor cycle in a simple motor system, the lamprey swimming network. In the region of dorsal fins the lamprey spinal cord contains two groups of motoneurons: the myotomal motoneurons that innervate the trunk muscles; and the fin motoneurons controlling muscle fibres of the dorsal fins. We investigated the activity of fin muscles during swimming in vivo and that of fin motoneurons during fictive swimming in vitro. During swimming in vivo with cycle periods of 4-8 Hz, fin muscle activity covered a broad portion of the cycle, with the peak of activity out-of-phase to the ipsilateral myotomal muscles. During fictive swimming evoked by N-methyl-d-aspartate in the isolated spinal cord, fin motoneurons expressed similar out-of-phase activity. The phase relationship of the synaptic drive to fin motoneurons was examined by recording their activity intracellular during fictive swimming. Three different forms of membrane potential oscillation with different time courses in the locomotor cycle could be distinguished. Sagittal lesions of the spinal cord in the segment where fin motoneurons are recorded and up to one segment rostral and caudal from it did not influence the out-of-phase activity pattern of the motoneurons. Our results indicate that coordination of fin motoneuron activity with the locomotor activity of myotomal motoneurons does not depend on intrasegmental contralateral premotor elements.

Animals↗

Electrically evoked fictive swimming in the low-spinal immobilized turtle.

Fictive swimming was elicited in low-spinal immobilized turtles by electrically stimulating the contralateral dorsolateral funiculus (cDLF) at the level of the third postcervical segment (D(3)). Fictive hindlimb motor output was recorded as electroneurograms (ENGs) from up to five peripheral nerves on the right side, including three knee extensors (KE; iliotibialis [IT]-KE, ambiens [AM]-KE, and femorotibialis [FT]-KE), a hip flexor (HF), and a hip extensor (HE). Quantitative analyses of burst amplitude, duty cycle and phase were used to demonstrate the close similarity of these cDLF-evoked fictive motor patterns with previous myographic recordings obtained from the corresponding hindlimb muscles during actual swimming. Fictive rostral scratching was elicited in the same animals by cutaneous stimulation of the shell bridge, anterior to the hindlimb. Fictive swim and rostral scratch motor patterns displayed similar phasing in hip and knee motor pools but differed in the relative amplitudes and durations of ENG bursts. Both motor patterns exhibited alternating HF and HE discharge, with monoarticular knee extensor (FT-KE) discharge during the late HF phase. The two motor patterns differed principally in the relative amplitudes and durations of HF and HE bursts. Swim cycles were dominated by large-amplitude, long-duration HE bursts, whereas rostral scratch cycles were dominated by large-amplitude, long-duration HF discharge. Small but significant differences were also observed during the two behaviors in the onset phase of biarticular knee extensor bursts (IT-KE and AM-KE) within each hip cycle. Finally, interactions between swim and scratch motor networks were investigated. Brief activation of the rostral scratch during an ongoing fictive swim episode could insert one or more scratch cycles into the swim motor pattern and permanently reset the burst rhythm. Similarly, brief swim stimulation could interrupt and reset an ongoing fictive rostral scratch. This shows that there are strong central interactions between swim and scratch neural networks and suggests that they may share key neural elements.

Animals↗

Kinematic analysis of butterfly turns of international and national swimmers.

The aims of this study were (1) to evaluate the different turn phases of 200 m butterfly during competition in a 50 m pool, (2) to determine if wall contact times are related to swim speed and (3) to compare the turn variables of a European Champion with other swimmers. In the first part of the study, we assessed the turns of 22 swimmers ranked in three groups according to 200 m butterfly swim performance (fast group = 121.73+/-3.03 s, intermediate group = 126.25+/-0.55 s, slow group = 129.24+/-2.30 s). Two turn times were recorded: the first before the turn (i.e. the time it takes the swimmer's head to reach the wall from 7.5 m away) and the second after the turn (i.e. the time from the wall to the point at which the swimmer's head passes 7.5 m away). The third turn was performed significantly faster by the fast group than by the slow group, both before (P< 0.01) and after (P< 0.02) the turn. In the second part of the study, objectives (2) and (3) were evaluated among 15 swimmers based on a specific protocol. Three cameras (50 Hz) simultaneously recorded the turn; these were placed above the water 10 m before the wall, 5 m before and just above the wall. Longer contact times of the feet on the wall were associated with a faster push-off speed (P < 0. 02). The European Champion achieved an improved contact time while performing a rapid pull-out speed.

Analysis of Variance↗

Stimulatory effects of Pseudosasa japonica leaves on exercise performance.

The performance-enhancing effects of Pseudosasa japonica were investigated in mice using an adjustable-current water pool. Compared to the control group, a 1.5-fold increase in swimming time was observed in the mouse group administered an 80% ethanol extract (PJE) of the leaves of P. japonica. The blood lactate level, an important indicator of fatigue, was significantly lower (28%, P<0.05) in PJE group than in the control group. These results suggest that PJE possesses stimulatory effects that can enhance exercise endurance and reduce fatigue.

Animals↗

Adaptations to six months of aerobic swim training. Changes in velocity, stroke rate, stroke length and blood lactate.

The purpose of this investigation was to determine how swimming velocity (SV), stroke rate (SR), stroke length (SL) and blood lactate concentration change as adaptations to six months of aerobic swim training. Subjects were trained male college swimmers (n = 8). Measurements were obtained following specially designed 400m freestyle swim tests, pre- and post-intervention. The swim test consisted of 4 x 400 m freestyle over two days. On day 1, subjects performed a maximal effort 400 m freestyle swimming trial; maximal mean velocity (Vmax) for each swimmer was calculated from this effort. On the next day, subjects were instructed to perform three 400 m freestyle swims at constant velocities equal to 85%, 90% and 95% of Vmax, respectively. Subjects rested one hour between swims. During each 400 m trial, lap time and time to complete 10 mid-pool strokes (50 m) were measured to determine SV (m.s-1), SR (stroke.min-1) and SL (m.stroke-1). Mixed arterial blood samples were taken at the end of each 400 m trial to evaluate blood lactate concentration. Results indicated that post-maximal swimming velocity (Vpostmax) increased significantly from pre-intervention measures (p < 0.05). Blood lactate concentration decreased significantly relative to SV and absolute lactate concentration following Vpostmax was significantly lower than that at Vpremax (p < 0.05). Six of seven subjects increased Vmax due to increases in SL. Mean SL during the second test was significantly higher (p < 0.05). Also, during the 400 m maximal test, SL increased significantly after sixth lap (p < 0.05). There was no significant difference between SRs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗

Submersion injuries in children younger than 5 years in urban Utah.

Submersion injuries of children younger than 5 years in 4 urban Utah counties from 1984 through 1988 were studied retrospectively to identify associated risk factors. Infants younger than 1 year had the highest rates of both submersion injuries and deaths. The incidence of bathtub drownings was 2 to 3 times higher than reported national rates. All bathtub drownings occurred while the victim was bathing with a young sibling (10 months to 7 years of age) without adult supervision. All drownings in pools and moving bodies of water (rivers, irrigation ditches) resulted from unintentional falls into the water rather than from swimming and wading activities. Drowning prevention strategies should focus on educating parents about the risk of young children bathing with siblings in the absence of adult supervision and fencing regulations for pools and open bodies of moving water.

Accidental Falls↗

31P-NMR studies of phosphate metabolites in intact red and white swimming muscles of cod (Gadus morhua L.).

31P-NMR was used to characterise intracellular phosphate pools and their post mortem changes at 7 degrees C in intact red and white cod muscles under anaerobic conditions. A total phosphate content of 55 and 60 mM was observed in red and white muscle, respectively. The concentration of P-creatine was 14 mM in the white and 9 mM in the red muscle, while that of inorganic phosphate, Pi (30 mM), ATP (9 mM), and sugar phosphate (5 mM) were similar in both muscles. During the first 90 min after death, the decrease in P-creatine showed a first order breakdown with a concomitant stoichiometric increase in Pi content, whereas the ATP and sugar phosphate remained the same. The intracellular pH decreased from 7.4 to 7.3 in this period. The steady-state rate constant of myosin ATPase was 0.0054 and 0.0022/min for red and white muscles, respectively. Individuals kept under diminished oxygen tension prior to being killed, showed a reduced P-creatine level in both muscles.

Adenosine Triphosphate↗