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PubMed1993

Is running style and economy affected by wearing respiratory apparatus?

The purposes of this investigation were to compare selected gait parameters characteristic of running without respiratory apparatus on a treadmill (NOR) with those displayed while wearing a mouthpiece-breathing valve apparatus (MP) and while wearing a respiratory face mask (MASK), and to compare the running economy (RE) measured during MP with that measured during MASK. Seventeen male volunteers [age = 32 +/- 5 yr (mean +/- SD); mass = 72.4 +/- 9.0 kg] performed three treadmill runs in randomly assigned order. All runs were identical in terms of duration (10 min), speed [200 m. min-2 (7.5 mph)], and grade (0%). During the last minute of each run, RE was measured and coordinate data were collected for determination of mechanical variables. The mechanical analyses were limited to 12 subjects. Stride length, vertical oscillation of the center of mass, hip and ankle range of motion, and average internal mechanical power output were not different for NOR, MP, and MASK. Knee range of motion was significantly less (P < or = 0.05) during MP than during NOR and MASK, primarily due to a significant reduction in maximum knee flexion during nonsupport. MASK RE was not significantly different (P > 0.05) from MP RE. It was concluded that wearing MP or MASK generally does not affect running style of individuals running at comfortable, submaximal running speeds and that RE measured with MP is not different from that measured with MASK.

Adult↗

PubMed1995

Anabolic-androgenic steroid increases running endurance in rats.

The study was designed to determine whether treatment with an anabolic-androgenic steroid enhances running performance in rats by increasing their freely chosen training distance. Forty male Long-Evans rats were randomly divided into either a sedentary control group or an exercising group caged in specially designed running wheels in which the rats were able to run spontaneously. After 4 wk, both groups were further subdivided into two groups receiving either 0.5-mg Durabolin (nandrolone phenylpropionate) (im) or 0.5-mg saline, every second day. After 8 wk, running distance was similar in both exercising groups. Rats receiving the anabolic-androgenic steroid ran 41% longer during the test of submaximal running endurance compared to the trained rats receiving saline (P < 0.05). Submaximal running endurance was not increased in sedentary rats receiving the anabolic-androgenic steroid. After 4 wk of training, the maximal sprinting speed increased by 29% in trained rats. There was no further increase in maximal sprinting speed after an additional 4 wk of training and treatment with either anabolic-androgenic steroid or saline treatment. Therefore, rats that train spontaneously while being treated with an anabolic-androgenic steroid had increased submaximal running endurance compared with trained rats treated with saline, despite the similar voluntary training distance and skeletal muscle oxidative capacity between the two groups. The mechanism by which treatment with an anabolic-androgenic steroid, combined with training, enhances submaximal running performance could not be identified and needs to be addressed in future studies.

Anabolic Agents↗

PubMed1996

Reproducibility of the blood lactate-running speed curve in horses under field conditions.

OBJECTIVE: To examine the reproducibility of blood lactate-running speed curve parameters derived by a curve-fit equation and by linear interpolation from the results of 4-speed tests of sport horses under field conditions. DESIGN: Thoroughbreds completed 10 test pairs with 3 to 11 days between tests and retest. ANIMALS: 7 Thoroughbreds. PROCEDURE: The 4-speed test consisted of 4 runs over a distance of 2,110 m. Exercise intensity was increased by 1 m/s for each run. Blood lactate concentration measured after each run was plotted against running speed to determine the blood lactate-running speed relation. By means of the blood lactate-running speed relation, velocity inducing 2, 2.5, 3, 3.5, or 4 mM blood lactate concentration was calculated by a curve-fit equation and by linear interpolation. RESULTS: The test-retest correlation coefficient of velocity inducing 2, 2.5, 3, 3.5, and 4 mM blood lactate concentration determined by curve-fit equation was 0.67, 0.78, 0.84, 0.86, and 0.86, respectively, and by linear interpolation was 0.42, 0.58, 0.77, 0.87, and 0.78, respectively. But the test-retest regression was equal to the line of identity only for velocity inducing 3.5 and 4 mM blood lactate concentration. CONCLUSIONS: The reproducibility of velocity inducing 3.5 and 4 mM blood lactate concentration was sufficient to be used to compare horses and evaluate conditioning effects. This holds both methods of calculation of the parameters derived from the blood lactate-running speed relation.

Animals↗

PubMed1997

Oxygen consumption and energy expenditure of level versus downhill running.

OBJECTIVE: The purpose of this study was to assess and compare submaximal oxygen consumption (VO2) and energy expenditure (kJ) while running at 0, -1.8, -3.6, and -5.4% grades for three individually selected running speeds (9.4 + 0.79, 10.3 + 0.74, 11.3 + 0.73 km.h-1). EXPERIMENTAL DESIGN: Subjects completed the four grade conditions in random order via a modified Latin squares design at three self-selected submaximal running speeds for each condition. PARTICIPANTS: Thirteen (5 females and 8 males) recreational (< 35 km.wk-1) runners (age: 27.7 +/- 4.3 yrs) volunteered for the study. MEASURES: Two-way repeated measures ANOVA (Grade x Speed) was used to analyze steady-state VO2 and kJ expenditure. Stepwise linear multiple regression was used to develop an equation for predicting VO2 for running at recreational speeds on moderately negative grades. RESULTS: VO2 and kJ mean values were significantly different between all speed and % grade comparisons. Compared to level grade, the average reductions in VO2 and kJ expenditure ranged from approximately 9% at a grade of -1.8% to 22% at a grade of -5.4%. The relationship between VO2 and % grade for each running speed was linear. CONCLUSIONS: For a given speed, running at a modest negative grade can significantly decrease VO2 and kJ expenditure compared to level running. The following regression equation can be used to estimate VO2 (ml.kg-1.min-1) for running at recreational speeds on slight downhills: VO2 = 6.8192 + 0.1313 (speed in m.min-1) + 1.2367 (% grade).

Adult↗

PubMed2006

Aesthetic and functional efficacy of subcuticular running epidermal closures of the trunk and extremity: a rater-blinded randomized control trial.

OBJECTIVE: To ascertain whether subcuticular epidermal closures of elliptical excisions of the trunk and extremities result in better functional and cosmetic outcomes than simple running epidermal closures of the same sites. DESIGN: Randomized controlled trial, with allocation of epidermal closure of elliptical excisions to 4 arms, including 1 control arm (simple running polypropylene sutures removed after 14 days) and 3 experimental arms (subcuticular running polypropylene sutures removed after 14 days, subcuticular running polypropylene sutures left in place, and subcuticular running polyglactin 910 sutures left in place). All experimental interventions were preceded by deep dermal closure with simple interrupted polyglactin 910 sutures. Interventions were delivered by 3 surgeons, who underwent 2 training sessions to minimize intersurgeon technique variability. SETTING: Institutional referral practice providing ambulatory care in an urban environment. PATIENTS: A consecutive sample of 36 adult patients (ages 18-65 years), each referred for concurrent elliptical excision of at least 2 clinically atypical nevi of the trunk and/or extremity, were included in the study. MAIN OUTCOME MEASURES: Primary outcome measures obtained at 3 and 9 months included scar width in millimeters and blinded observer ordinal scale assessment of overall scar appearance. Secondary outcome measures included ratings on the standardized Vancouver Scar Scale and the Hollander Scar Scale; an additional nonstandard item was added to assess pruritus. RESULTS: No difference among groups was found in scar width at 3 or 9 months. Differences among groups were detected in overall scar appearance (3 months, P<.001; 9 months, P<.001), vascularity (3 months, P = .001; 9 months, P<.001), excessive distortion (3 months, P = .04; 9 months, P = .02), contour irregularity (3 months, P<.001), and edge inversion (3 months, P = .01). The best overall appearance was with a subcuticular running polyglactin 910 suture left in place, and the next best was with a subcuticular running polypropylene suture left in place; differences across groups persisted but decreased in intensity at 9 months. A secondary analysis that matched high-tension anatomic sites (back and lower leg), and high and moderate tension sites (also chest and shoulder) yielded the same main effects and mostly the same results in pairwise comparisons. CONCLUSION: While scar width does not appear to vary significantly based on choice of epidermal closure, bilayered closures of the trunk and extremity have better overall appearance and less associated erythema at 3 and 9 months after surgery with the use of a subcuticular running polyglactin 910 suture left in place.

Abdomen↗

PubMed1990

Effect of ambient temperature and running wheel activity on the outcome of pregnancy in CD-1 mice.

The effect of ambient temperature and running activity on fetal outcome was studied in CD-1 mice. Pregnant mice were allowed to be active in a running wheel at various ambient temperatures (26, 30, 32, 34, or 36 degrees C) for 100 min a day. The dams were killed near term, and various maternal and fetal measures made. Mean deep body temperature (measured using radio-telethermometers implanted in the abdomen) of pregnant dams was raised to 39.5 degrees C while running at an ambient temperature of 36 degrees C. Bred mice, pregnant or not, continued to increase their running activity, but pregnant mice exercised less from mid-pregnancy on. Running up to 1 km/hr had no effect on maternal weight gain, number of implantations, number of live fetuses, fetal body weight, and fetal relative brain weight. However, increasing ambient temperature was effective in decreasing maternal weight gain and fetal body weight and increasing fetal relative brain weight. Even though body temperature can be increased significantly by increasing either running rate or ambient temperature, the body temperature increase caused by running appears to have no significant influence on the outcome of pregnancy. At levels in this study, body temperature per se does not appear to be the variable on which to predict fetal effects. This is because only body temperature raised by higher ambient temperature, and not body temperature raised by increased running, was shown to effect a fetal change.

Animals↗

PubMed1998

Voluntary wheel running: a review and novel interpretation.

Voluntary wheel running by animals is an activity that has been observed and recorded in great detail for almost a century. This review shows that it is performed, often with startling intensity and coordination, by a wide variety of wild, laboratory and domestic species with diverse evolutionary histories. However, despite the plethora of published studies on wheel running, there is considerable disagreement between many findings, thus leading to a lack of consensus on explanations of the causality and function. In the initial part of this review, I discuss the internal and external factors that may be involved in the causality of this behaviour, with an emphasis on disparities in both the factual and theoretical development of the subject. I then address the various proposed functions of wheel running, again highlighting evidence to the contrary. This leads to the conclusion that any single theory on the basis of wheel running is likely to be simplistic with little generality. I then present a novel, behaviour-based interpretation in which it is argued that wheel running has no directly analogous naturally occurring behaviour, it is (sometimes) performed for its own sake per se rather than as a redirected or substitute activity, and studies on motivation show that wheel running is self-reinforcing and perceived by animals as 'important'. This review proposes that wheel running may be an artefact of captive environments or of the running-wheel itself, possibly resulting from feedback dysfunction. I also discuss the ubiquity and intensity of its performance, along with its great plasticity and maladaptiveness, all indicating that if it is an artefact, it is nevertheless one of great interest to behavioural science. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed1995

Action of calpastatin in prevention of cardiac L-type Ca2+ channel run-down cannot be mimicked by synthetic calpain inhibitors.

Activity of L-type Ca2+ channels in a membrane patch disappears rapidly when the patch is excised from the cell into an artificial solution. This channel run-down observed in isolated membrane patches can however, be prevented by application of calpastatin, an endogenous protease inhibitor, and ATP. The high specificity of calpastatin for the protease calpain would clearly point to a participation of calpain activity in the run-down of Ca2+ channels. In an attempt to examine a possible involvement of calpain, three synthetic and rather specific calpain inhibitors were substituted for calpastatin. One of these inhibitors chosen for its membrane permeability in addition allowed calpain activity to be inhibited even before patch excision. The potency of these compounds in inhibiting calpain, specifically mu- and m-calpain, was first determined in a biochemical assay and then compared with their efficacy in preventing Ca2+ channel run-down. Surprisingly, calpastatin was least effective in calpain inhibition but by far the most potent in prevention of Ca2+ channel run-down. In addition run-down of Ca2+ channel activity was examined for its reversibility, which would not be expected upon involvement of a proteolytic process. However, Ca2+ channel activity clearly recovered after run-down by application of calpastatin. In contrast, synthetic calpain inhibitors were unable to reverse Ca2+ channel run-down. These results indicate that proteolysis might only be partially responsible for channel run-down and suggest an as yet unidentified function for calpastatin beyond its inhibitory action on calpain in the regulation of Ca2+ channel activity.

Adenosine Triphosphate↗

PubMed1976

A comparison of maximum oxygen uptake determination by bicycle ergometry at various pedaling frequencies and by treadmill running at various speeds.

Tests of performance on a bicycle ergometer have routinely been standardized with pedaling frequencies of up to 60 rpm. Only rarely have higher speeds been used. It may be hypothesized than a higher VO2, more closely approximating the maximum attainable by treadmill running, may be achieved in bicycle ergometry if higher pedal frequencies are used so that premature fatigue of the leg musculature does not obscure the comparison. Even in treadmill running it remains equivocal which combination of speed and grade of running will produce a maximum VO2. Five male subjects performed maximally at pedal frequencies of 60, 80, 100 and 120 rpm and running speeds of 6.0, 6.5, 7.0, and 7.5 mph, on a bicycle and treadmill respectively. Power output on the bicycle and increasing grade sequence on the treadmill were maintained constant for each speed investigated. The highest VO2 attained in each test was measured and compared both within and between the modes of testing. It was confirmed that peak VO2 during bicycle ergometry is significantly less than VO2 max attained in treadmill running. Pedal frequencies of 80 and 100 rpm produced optimal VO2's in ergometry. No differences were noted between VO2's determined at any speed of treadmill running. Subjects preferred 60 or 80 rpm in ergometry and 6.0 and 7.0 mph in treadmill running; 120 rpm and 7.5 mph in bicycling and treadmill running, respectively, were generally disliked.

Humans↗

PubMed1983

Coupling interval and types of ventricular ectopic activity associated with ventricular runs.

Repetitive 10-hour ECG recordings of 289 patients obtained within a year after myocardial infarction were analyzed for the presence of ventricular runs, and their association with various types of ventricular ectopic activity (VEA), average rate of premature ventricular complexes (PVCs), and coupling interval of PVCs initiating the runs. Tapes which contained complex VEA (bigeminy, multiform PVCs, couplets, or runs), early PVCs (coupling interval less than 400 msec), or late PVCs (coupling interval greater than 600 msec) had a substantially higher average PVC rate than those without them. The occurrence of ventricular runs was significantly more likely in tapes having other complex VEA or late PVCs than in those without them, and when tapes were stratified by PVC rates the presence of these dysrhythmias appeared to have an independent predictive value for the occurrence of runs. In contrast, the influence of early PVCs on the occurrence of runs was rather minimal, and this seemed to be related to their common association with the PVC rate. Furthermore, a larger percentage of isolated PVCs had coupling intervals between 400 msec and 600 msec, and most couplets (77%) and runs (67.8%) were initiated by PVCs with coupling intervals in this range. However, the proportion of either short (less than 400 msec) or long (greater than 600 msec) coupling interval PVCs initiating couplets or runs was significantly higher than those with intermediate coupling intervals (between 400 and 600 msec).

Arrhythmias, Cardiac↗

PubMed1993

Interaction between excitatory and inhibitory amino acids in the ventromedial nucleus of the hypothalamus in inducing hyper-running.

We have previously shown that blockade of neurotransmission mediated by gamma-aminobutyric acid (GABA) in the ventromedial nucleus of the hypothalamus (VMH) by the microinjection of a GABAA receptor antagonist, bicuculline methiodide (BM), exclusively induced running activity in the rat. The purpose of the present study was to examine the role of receptors for excitatory amino acids (EAAs) in the VMH in inducing hyper-running and to clarify the interaction between GABA and EAAs in the VMH in controlling running activity. Although the injection of neither N-methyl-D-aspartate (NMDA) nor quisqualate into the VMH induced hyper-running, kainate (KA) produced running activity in a dose-dependent manner with similar features to that induced by BM. This effect of KA was blocked by a non-NMDA receptor antagonist, 6,7-dinitroquinoxaline-2,3-dione (DNQX). GABA injected simultaneously with KA into the VMH failed to affect hyper-running induced by KA. On the other hand, DNQX significantly suppressed the BM-induced running activity. These results suggest that endogenous EAAs acting on the KA-type receptor in the VMH facilitates running activity and that the release of such EAAs from the nerve terminal is presynaptically inhibited by GABA.

Animals↗

PubMed1990

Suppression of food deprivation-induced high-rate wheel running in rats.

To test for involvement of endogenous opioids in the maintenance of high-rate running we have administered naloxone, a specific opioid antagonist, to rats. The animals were stabilized voluntarily running 6000 to 8000 m/day through a standard protocol and maintained in this state on approximately 18 g of food per day. Naloxone (50 mg/kg in saline) or saline alone was injected intraperitoneally on alternate days for 20 days. All rats ran less on days when naloxone was administered. The mean distance run for the group (N = 6, mean +/- SE) was: saline: 6401 +/- 985; naloxone: 5344 +/- 805 m/day. This difference was highly significant (p less than 0.001). In the 4-hour period immediately following the naloxone injection there was no inhibition of running. The second four-hour period showed a nonsignificant (p greater than 0.05) decrease in running. Inhibition of running was highly significant after eight hours (30%, p less than 0.001). The results demonstrate a clear inhibition of the high-rate running by naloxone and imply a significant role by endogenous opioids in the maintenance of running. The time course of the inhibition is consistent with the relatively high initial concentrations of naloxone exerting an agonist action and the subsequent lower levels having an antagonist effect.

Animals↗

PubMed1993

Effects of wheel running on glucose transporter (GLUT4) concentration in skeletal muscle of young adult and old rats.

We examined the effects of voluntary exercise on glucose transporter concentration in skeletal muscle from young adult and old female Long-Evans rats. Rats had free access to voluntary running wheels beginning at 4 months of age or remained sedentary. Exercising rats ran approximately 7.5, 6.2, 5.6 and 5.3 km/day during their 6th, 8th, 9th and 10th month of age, respectively. During the 23rd, 24th and 25th month of age running distance averaged 3.0, 2.8 and 2.4 km/day, respectively. At 10 and 25 months of age, glucose transporter protein concentration was assessed in epitrochlearis and flexor digitorum brevis muscles with a polyclonal antibody directed against the GLUT4 transporter isoform. GLUT4 protein concentration was not altered by the aging process (i.e., comparing 10- and 25-month-old rats) in either muscle type. Wheel running increased GLUT4 protein concentration by 45% in epitrochlearis muscles of 10-month-old rats relative to age-matched sedentary controls. The training-induced adaptation in GLUT4 protein was no longer present at age 25 months, probably because the running distance had declined by 50%. In the flexor digitorum brevis, exercise did not alter GLUT4 concentration at either 10 or 25 months, presumably due to insufficient recruitment of this muscle during wheel running as assessed by measurement of citrate synthase and hexokinase enzyme activities. Wheel running induced cardiac and soleus muscle hypertrophy in 10- and 25-month-old rats. In summary, voluntary wheel running can induce an increase in skeletal muscle GLUT4 protein concentration in adult rats. Older rats that run less exhibit cardiac and soleus muscle hypertrophy, but do not maintain an elevated GLUT4 protein concentration in the epitrochlearis muscle. Aging does not alter GLUT4 protein concentration in the epitrochlearis or FDB muscles.

Aging↗

PubMed1996

Relationship between vertical ground reaction force and speed during walking, slow jogging, and running.

OBJECTIVE: To obtain descriptive information between vertical ground reaction force (GRF)-time histories and gait speed, running style, and gender. DESIGN: GRF-time history measurements were obtained from male and female subjects during walking, slow jogging, jogging and running on an indoor platform. BACKGROUND: Previous studies have established GRF descriptor variables for male subjects running at speeds from 3 to 6 m s(-1), but very little descriptive data exists for slower or faster running, nor have previous studies reported GRF descriptors separately for female subjects. METHODS: GRF-time histories were recorded for 13 male and 10 female recreational athletes during walking and slow jogging at speeds between 1.5 and 3.0 m s(-1), and running at speeds between 3.5 and 6.0 m s(-1). Vertical GRF-time data for trials with speeds within 0.2 m s(-1) of the prescribed speed were analysed to determine thrust maximum GRF (F(z)) and loading rate (G(z)). RESULTS: In both male and female subjects, F(z) increased linearly during walking and running from 1.2 BW to approximately 2.5 BW at 6.0 m s(-1), remaining constant during forward lean sprinting at higher speeds. F(z) was linearly correlated to G(z), the latter ranging from 8 to 30 BW s(-1) over this speed range. Slow jogging was associated with a > 50% higher F(z) and G(z) in comparison to walking or fast running. CONCLUSIONS: Similar GRF descriptor data and velocity relationships were obtained for male and female subjects. Impact forces were greatest when the subjects adopted a higher, less fixed centre of gravity during slow jogging. RELEVANCE: These results suggest that vertical GRF norms can be established for male and female subjects alike, and that slow or fast running with a lower, fixed centre of gravity decreases impact forces.

Journal Article↗

PubMed2004

Taste avoidance induced by wheel running: effects of backward pairings and robustness of conditioned taste aversion.

Rats repeatedly exposed to a distinctive novel solution (conditioned stimulus, CS) followed by the opportunity to run in a wheel subsequently drink less of this solution. Investigations on this phenomenon indicate that wheel running is an effective unconditioned stimulus (US) for establishing conditioned taste aversion (CTA) when using a forward conditioning procedure (i.e., the US-wheel running follows the CS-taste). However, other studies show that wheel running produces reliable preference for a distinctive place when pairings are backward (i.e., the CS-location follows the US-wheel running). One possibility to account for these results is that rewarding aftereffects of wheel running conditioned preference to the CS. The main objective of the present study was to assess the effects of backward conditioning using wheel running as the US and a distinctive taste as the CS. In a between-groups design, two experimental groups [i.e., forward (FC) and backward conditioning (BC)] and two control groups [CS-taste alone (TA) and CS-US unpaired (UNP)] were compared. Results from this experiment indicated that there is less suppression of drinking when a CS-taste followed a bout of wheel running. In fact, rats in the BC group drank more of the paired solution than all the other groups.

Animals↗

PubMedDate not supplied

Place DMTS water-escape with direct placement or response information runs.

A two-choice, spatial delayed matching-to-sample (DMTS) water-escape task has proved to be a valuable of assay of trial-dependent memory. The task involves giving rats trials consisting of a forced-choice information run and a free-choice test run that are separated by a 5-m retention interval. Two experiments were conducted to determine the importance of making a complete response (R), partial response (P), or no response (NR; direct placement on escape platform) during the information "run" on acquisition and the subsequent performance of the task. Most of the naive, male, Sprague-Dawley rats were capable of attaining a 90% correct choice criterion when trained with P or NR information runs, but rats trained with R information runs required fewer trials to attain criterion and had shorter escape latencies during the criterion trials. Rats in all three groups showed significant retention at retention intervals as long as 1 h. Rats overtrained on the task with R information runs were subsequently able to perform the task at above chance level, regardless of the type information run given on the trial, but performed more accurately on trials where they made P or R information runs. Thus, rats use and perform better on place DMTS when allocentric environmental and egocentric response-associated cues are both available.

Animals↗

PubMed2002

Pre-exposure to wheel running disrupts taste aversion conditioning.

When rats are given access to a running wheel after drinking a flavored solution, they subsequently drink less of that flavor solution. It has been suggested that running produces a conditioned taste aversion (CTA). This study explored whether CTA is eliminated by prior exposure to wheel running [i.e., unconditioned stimulus (UCS) pre-exposure effect]. The rats in the experimental group (UW) were allowed to wheel run for 1 h daily for seven consecutive days of pre-exposure. Rats in the two other groups had either access to locked wheels (LW group) or were maintained in their home cages (HC group) during the pre-exposure days. All rats were then exposed to four paired and four unpaired trials using a "ABBAABBA" design. Conditioning trials were composed of one flavored liquid followed by 60-min access to wheel running. For the unpaired trials, rats received a different flavor not followed by the opportunity to run. All rats were then initially tested for water consumption followed by tests of the two flavors (paired or unpaired) in a counterbalanced design. Rats in the UW group show no CTA to the liquid paired with wheel running, whereas LW and HC groups developed CTA. These results indicate that pre-exposure to wheel running (i.e., the UCS), eliminates subsequent CTA.

Aging↗

PubMed1997

Body temperature and wheel running predict survival times in rats exposed to activity-stress.

The relationship between restricted feeding, core body temperature (Tb), wheel running, survival, and gastric erosion formation was examined in female rats exposed to activity-stress. Core body temperature and gross motor activity were telemetrically monitored in four groups of rats that had free access to running wheels and in one group that was not allowed to run on the wheels. Twenty-four hours prior to the onset of hypothermia and predicted mortality, different groups were left undisturbed, warmed with a heat lamp, denied access to running wheels, or euthanized. Length of survival in wheel-running rats varied from 2 to 12 days. During the first day of food deprivation, premorbid changes in the variability of Tb during the diurnal period and the mean number of wheel revolutions during the nocturnal period were strongly predictive of length of survival. Warming rats with a heat lamp or preventing rats from ever running on the wheel increased the length of survival and attenuated gastric erosion formation. Only rats that were warmed had a greater likelihood of survival. Gastric pathology was also reduced in rats that were euthanized prior to becoming moribund. Rats that were left undisturbed or locked from the running wheel over the last 24 h of testing became moribund and had extensive gastric mucosal damage. These results indicate that thermoregulatory disturbances induced by restricted feeding and not wheel running alone are critical in determining survival and the degree of gastric mucosal injury in rats exposed to activity-stress. Results further suggest that predisposing factors may put some rats at risk for the development of activity-stress-induced mortality.

Animals↗