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PubMedDate not supplied

Chronic morphine consumption decreases wheel running and wheel running-reinforced behavior in rats.

The purpose of this experiment was to evaluate the effects of morphine self-administration on wheel running and wheel running-reinforced lever pressing in rats. The home cage was equipped with a bottle that contained either water, a saccharin-flavored 0.5-mg/ml morphine solution, or saccharin (0.25%). The bottle was available for either 1 or 3 h. The bottle was then removed, and 20-22 h after removal, the rats were moved to an operant chamber in which lever presses earned 15 s access to a running wheel (according to a variable interval (VI) 40-s schedule). The morphine condition was in effect for 69 days, and consumption gradually increased to a level of 67 mg/kg/day. During the morphine condition, wheel running and lever pressing decreased. Following the removal of morphine, (so that the home-cage bottles provided a 0.25% saccharin solution), the two instrumental behaviors increased to the pre-morphine (water) levels. However, the increases were not immediate, and in the first post-morphine session, lever pressing and wheel turning remained at the depressed morphine level. The post-morphine increase in lever pressing was substantially larger than the increase in wheel running. The results support the hypothesis that chronic opiate consumption reduces the frequency of some nondrug-related behaviors, and that this, in turn, increases preference for the opiate.

Animals↗

PubMed1998

Contribution of the lower extremity joints to mechanical energy in running vertical jumps and running long jumps.

The energy contribution of the lower extremity joints to vertical jumping and long jumping from a standing position has previously been investigated. However, the resultant joint moment contributions to vertical and long jumps performed with a running approach are unknown. Also, the contribution of the metatarsophalangeal joint to these activities has not been investigated. The objective of this study was to determine the mechanical energy contributions of the hip, knee, ankle and metatarsophalangeal joints to running long jumps and running vertical jumps. A sagittal plane analysis was performed on five male university basketball players while performing running vertical jumps and four male long jumpers while performing running long jumps. The resultant joint moment and power patterns at the ankle, knee and hip were similar to those reported in the literature for standing jumps. It appears that the movement pattern of the jumps is not influenced by an increase in horizontal velocity before take-off. The metatarsophalangeal joint was a large energy absorber and generated only a minimal amount of energy at take-off. The ankle joint was the largest energy generator and absorber for both jumps; however, it played a smaller relative role during long jumping as the energy contribution of the hip increased.

Adult↗

PubMed1998

Energy cost and running mechanics during a treadmill run to voluntary exhaustion in humans.

The aim of the present study was to examine the physiological and mechanical factors which may be concerned in the increase in energy cost during running in a fatigued state. A group of 15 trained triathletes ran on a treadmill at velocities corresponding to their personal records over 3000m [mean 4.53 (SD 0.28) m x s(-1)] until they felt exhausted. The energy cost of running (CR) was quantified from the net O2 uptake and the elevation of blood lactate concentration. Gas exchange was measured over 1 min firstly during the 3rd-4th min and secondly during the last minute of the run. Blood samples were collected before and after the completion of the run. Mechanical changes of the centre of mass were quantified using a kinematic arm. A significant mean increase [6.9 (SD 3.5)%, P < 0.001] in CR from a mean of 4.4 (SD 0.4) J x kg(-1) x m(-1) to a mean of 4.7 (SD 0.4) J x kg(-1) x m(-1) was observed. The increase in the O2 demand of the respiratory muscles estimated from the increase in ventilation accounted for a considerable proportion [mean 25.2 (SD 10.4)%] of the increase in CR. A mean increase [17.0 (SD 26.0)%, P < 0.05] in the mechanical cost (CM) from a mean of 2.36 (SD 0.23) J x kg m(-1) to a mean of 2.74 (SD 0.55) J x kg(-1) x m(-1) was also noted. A significant correlation was found between CR and CM in the non-fatigued state (r=0.68, P < 0.01), but not in the fatigued state (r=0.25, NS). Furthermore, no correlations were found between the changes (from non-fatigued to fatigued state) in CR and the changes in CM suggesting that the increase in CR is not solely dependent on the external work done per unit of distance. Since step frequency decreased slightly in the fatigued state, the internal work would have tended to decrease slightly which would not be compatible with an increase in CR. A stepwise regressions showed that the changes in CR were linked (r=0.77, P < 0.01) to the changes in the variability of step frequency and in the variability of potential cost suggesting that a large proportion of the increase in CR was due to an increase in the step variability. The underlying mechanisms of the relationship between CR and step variability remains unclear.

Adult↗

PubMed1987

The influence of running velocity and midsole hardness on external impact forces in heel-toe running.

The purpose of this study was to investigate the influence of midsole hardness and running velocity on external impact forces in heel-toe running. Fourteen subjects were assessed with a force platform and high speed film while running at speeds of 3, 4, 5 and 6 m s-1. The result showed that running velocity does influence external impact force peaks (linear connection) and that midsole hardness does not influence magnitude and loading rate of the external vertical impact forces. Changes in kinematic and kinetic data can be used to explain this result mechanically. However, the neuromuscular control mechanisms to keep external impact forces constant are not known.

Biomechanical Phenomena↗

PubMed1990

Relationship of running economy, ventilatory threshold, and maximal oxygen consumption to running performance in high school females.

The purpose of the study was to relate three determinants of distance running success, (a) maximal oxygen consumption (VO2max), (b) ventilatory threshold (VT), and (c) running economy (RE), to actual running time in a 5-km race (ART). Twenty-four female runners (M age = 15.9 years) from four high school teams that competed at the Massachusetts All-State 5-km Cross Country Championship Meet and placed 1st, 7th, 19th, and 20th were tested in the laboratory. The mean VO2max of these runners was 61.7 ml.kg-1.min-1, HRmax 201 b.min-1, VEmax 100 L.min-1, and RER 1.10. The VT occurred at 79% of the VO2max, and HR of 184 b.min-1 (92% of HRmax). The velocity at VT (vVT) and velocity at VO2max (vVO2max) was correlated with ART, r(22) = .78 and .77 (p less than .001), respectively. The VO2 at VT and at maximal exercise was correlated with ART by r(22) = -.66 and -.69 (p less than .001), respectively. The VO2 at 215 m.min-1 (8 mph) was poorly related to ART, r(22) = -.05, p greater than .05. It was concluded that either of the derived variables vVT and vVO2max appear to explain significant variation in distance running performance among adolescent female cross country runners.

Adolescent↗

PubMed1998

Energetics of bipedal running. II. Limb design and running mechanics.

Compared with quadrupeds, bipedal runners of the same weight have longer legs, take longer steps and can presumably use slower, more economical muscle fibers. One might predict that bipedal running is less expensive, but it is not. We hypothesized that bipeds recruit a larger volume of muscle to support their weight, eliminating the potential economy of longer legs and slower steps. To test our hypothesis, we calculated the relative volume of muscle needed to support body weight over a stride in small dogs (Canis familiaris) and wild turkeys (Meleagris gallopavo) of the same weight. First, we confirmed that turkeys and dogs use approximately the same amount of energy to run at the same speed, and found that turkeys take 1. 8-fold longer steps. Higher muscle forces and/or longer muscle fibers would require a greater volume of active muscle, since muscle volume is proportional to the product of force and fascicle length. We measured both mean fascicle length and mean mechanical advantage for limb extensor muscles. Turkeys generated approximately the same total muscle force to support their weight during running and used muscle fascicles that are on average 2.1 times as long as in dogs, thus requiring a 2.5-fold greater active muscle volume. The greater volume appears to offset the economy of slower rates of force generation, supporting our hypothesis and providing a simple explanation for why it costs the same to run on two and four legs.

Animals↗

PubMed2001

Deep water running: an effective non-weightbearing exercise for the maintenance of land-based running performance.

Deep water running (DWR) has become a well-recognized from of cardiovascular conditioning for injured athletes and has been used successfully to maintain running performance. DWR provides for decreased stress and weightbearing to injured tissue and joints, allows for maintenance of cardiovascular fitness and a training effect, and offers greater specificity of exercise in relation to running. During a 22-month period, 181 active duty Army soldiers, placed on temporary profiles for injuries that precluded them from their regular weightbearing physical fitness activities, participated in a DWR program. Injuries to the back, knee, and ankle were the most common reasons for referral to the program. This article reviews the physiological characteristics of DWR, specifics of DWR program design, DWR mechanics, and the advantages of DWR over other aerobic forms of exercise to maintain land running performance in military personnel on temporary non-weightbearing profiles.

Adolescent↗

PubMed2006

Visualization of synchronization of the uterine contraction signals: running cross-correlation and wavelet running cross-correlation methods.

In physiological research, we often study multivariate data sets, containing two or more simultaneously recorded time series. The aim of this paper is to present the cross-correlation and the wavelet cross-correlation methods to assess synchronization between contractions in different topographic regions of the uterus. From a medical point of view, it is important to identify time delays between contractions, which may be of potential diagnostic significance in various pathologies. The cross-correlation was computed in a moving window with a width corresponding to approximately two or three contractions. As a result, the running cross-correlation function was obtained. The propagation% parameter assessed from this function allows quantitative description of synchronization in bivariate time series. In general, the uterine contraction signals are very complicated. Wavelet transforms provide insight into the structure of the time series at various frequencies (scales). To show the changes of the propagation% parameter along scales, a wavelet running cross-correlation was used. At first, the continuous wavelet transforms as the uterine contraction signals were received and afterwards, a running cross-correlation analysis was conducted for each pair of transformed time series. The findings show that running functions are very useful in the analysis of uterine contractions.

Dysmenorrhea↗

PubMed2005

Run-to-run control of meal-related insulin dosing.

BACKGROUND: This study was designed to determine if it was feasible to use a run-to-run algorithm to improve postprandial glucose concentrations in individuals with type 1 diabetes mellitus (T1DM). METHODS: Fourteen subjects were recruited for this 10-week study. During the initial phases of the study, the following information was derived for each subject: basal insulin infusion rates, insulin-to-carbohydrate ratios, insulin correction factors for hyperglycemia, and insulin sensitivities. During the final phases, the algorithm was used to suggest preprandial insulin doses, with a goal of bringing the postprandial glucose into a predetermined target range within 3-7 days. RESULTS: In the single-meal phase (phase 5), 33% of the subject-meal responses were convergent in 3-4 days to a clinically acceptable range, 33% always stayed in range, and 33% had divergent responses, incorrect sensitivities, and/or other mitigating circumstances. In the three-meal phase (phase 6), 41% of the subject-meal responses were convergent in 3-4 days to a clinically acceptable range, 26% were always in range, and 33% had divergent responses, incorrect sensitivities, and/or other mitigating circumstances. CONCLUSIONS: Overall, we were able to safely demonstrate that run-to-run control can be used to manage meal-related insulin in subjects with T1DM.

Algorithms↗

PubMed2006

Run-to-run control of blood glucose concentrations for people with Type 1 diabetes mellitus.

Run-to-run control has been applied to several traditional batch processes in the chemical industry. The 24-h cycle of eating meals, measuring blood glucose concentrations, and delivering the correct insulin bolus, with the goal of achieving the optimal blood glucose profile, can be viewed in the same spirit as traditional batch processes such as emulsion polymerization. In this paper, we aim to exploit the "repetitive" nature of the insulin therapy of people with Type 1 diabetes. A run-to-run algorithm is used on a virtual diabetic patient model to control blood glucose concentrations. The insulin input is parameterized into the timing and amount of the dose while the glucose output is parameterized into the maximum and minimum glucose concentrations. Robustness of the algorithm to variations in the meal amount, meal timing, and insulin sensitivity parameter is addressed. In general, the algorithm is able to converge when the meal timing is varied within +/- 40 min. If the meal size is underestimated by approximately 10 grams (g), the algorithm is able to converge within a reasonable time frame for breakfast, lunch, and dinner. If the meal size is overestimated by 20-25 g, the algorithm is able to converge. When random variations in the meal timing and the meal amount are introduced, the variation on the output variables, Gmax and Gmin, scales according to the amount of variation allowed. Along with this, the insulin sensitivity of the virtual patient model is varied. The algorithm is robust for differences in insulin sensitivity less than +/- 50% of the nominal value.

Blood Glucose↗

PubMed2003

These studies were conducted to assess the effects of lead toxicity on exploratory behavior and running. Effects of lead on exploratory behavior and running speed in the shrew, Blarina brevicauda (Insectivora).

These studies were conducted to assess the effects of lead toxicity on exploratory behavior and running speed in the short-tailed shrew, Blarina brevicauda. Shrews from the experimental group received 25 mg/kg/day of lead acetate in their drinking water for a period of 90 days. Control subjects received sodium acetate. Exploratory behavior was determined using a computerized activity chamber where movements of test subjects broke infrared beams projected onto the floor of the apparatus. Time spent (sec) in exploration was recorded over eight 6-min intervals. Running speed (km/hr) was measured in a microprocessor-controlled rectangular racetrack fitted with photocell timers. With respect to time spent in exploration, there were significant differences between lead-exposed (20.5-23.9 sec per 6-min testing session) and control subjects (6.8-8.1 sec) after the sixth testing interval in the activity chamber. With respect to maximal running speed, control subjects ran significantly faster (mean: 14.8 km/hr) than their lead-exposed counterparts (5.83 km/hr). Lead-exposed animals exhibited hyperactivity and increased random locomotor movements. They would frequently bump into the walls and their movements were more random. Controls typically ran along the racetrack in a straight line. These results represent the first data for the effects of lead exposure on exploratory behavior and running speed for shrews.

Animals↗

PubMed2006

Influence of M. tibialis anterior fatigue on the walk-to-run and run-to-walk transition in non-steady state locomotion.

The purpose of this study was to examine the influence of muscular fatigue of tibialis anterior (TA) on the walk-to-run transition (WRT) and run-to-walk transition (RWT) when speed is altered at different constant accelerations (a=0.01, 0.07 and 0.05 ms(-2)). Twenty women (height: 168.9+/-3.36 cm) performed WRTs and RWTs on a motor-driven treadmill, before and after a protocol inducing muscular fatigue of the TA. WRT-speed decreased after TA fatigue whereas RWT-speed did not change except during the intermediate deceleration. Integrated EMG (iEMG) of the activity burst of TA around heel contact was examined in the last steps before transition, the transition step and the first steps after transition. iEMG increased before WRT, then decreased after transition to running. In the RWT the opposite was observed: iEMG increased after RWT, then decreased with decreasing walking speed. After inducing fatigue in the TA, there was a decrease in iEMG in the WRT whereas no influence of fatigue was found on iEMG in the RWT. As a result of TA fatigue, WRT occurred at a lower speed, probably to avoid over-exertion of the TA. This indicates that the TA is a likely determinant of WRT as previously reported. The RWT, on the other hand, was not altered following TA fatigue, which would indicate that WRT and RWT are determined by different factors.

Acceleration↗

PubMed2005

A comparison of forefoot stiffness in running and running shoe bending stiffness.

This study characterizes the stiffness of the human forefoot during running. The forefoot stiffness, defined as the ratio of ground reaction moment to angular deflection of the metatarsophalangeal joint, is measured for subjects running barefoot. The joint deflection is obtained from video data, while the ground reaction moment is obtained from force plate and video data. The experiments show that during push-off, the forefoot stiffness rises sharply and then decreases steadily, showing that the forefoot behaves not as a simple spring, but rather as an active mechanism that exhibits a highly time-dependent stiffness. The forefoot stiffness is compared with the bending stiffness of running shoes. For each of four shoes tested, the shoe stiffness is relatively constant and generally much lower than the mean human forefoot stiffness. Since forefoot stiffness and shoe bending stiffness act in parallel (i.e., are additive), the total forefoot stiffness of the shod foot is dominated by that of the human foot.

Adult↗

PubMed2002

Duodenal motility during a run-bike-run protocol: the effect of a sports drink.

OBJECTIVE: To examine the effect of a sports drink during strenuous exercise on duodenal motility and gastrointestinal symptoms. METHODS: In a cross-over design, seven male triathletes performed two 170-min run-bike-run tests at about 70% peak oxygen uptake (O(2peak)), with either a 7% carbohydrate (CHO) sports drink or tap water. Antroduodenal motility (phase III of the migrating motor complex; MMC) was measured with an ambulant manometry system. The effect of the two exercise trials on the first appearance of the MMC was assessed in the postprandial period. RESULTS: Exercise heart rate, percentage O(2peak) and loss of body mass did not differ significantly between the two trials. After the start of the exercise, the expected time before the first phase III occurrence, based on the actual energy intake of the last meal in the morning before exercise (1048 +/- 294 kcal), a fixed gastric emptying rate and a lag phase for solid food, was 183 +/- 113 min (mean +/- standard deviation [SD]). The real time period between the start of the exercise with CHO and the first phase III was 63 +/- 61 min, which was significantly shorter than that observed with tap water (152 +/- 59 min). Both real time periods were shorter than the expected time period of 183 +/- 113 min (P < 0.05). During exercise, the number of subjects with a phase III was higher with CHO than with tap water (n =6 v. n =1; P < 0.05). Also, the median number of phases III per hour with CHO was higher than with tap water (0.4 v. 0.0; P < 0.05). During cycling, significantly more phases III per hour (0.9) were measured than during running (0.2). All subjects reported one or more gastrointestinal symptoms during exercise, however, without a clear association with the mode of exercise or supplementation. CONCLUSIONS: Prolonged exercise results in gastrointestinal symptoms and a significant interruption of postprandial motility. Only the latter phenomenon depends on the mode of exercise and supplementation.

Adult↗

PubMed1999

Explosive-strength training improves 5-km running time by improving running economy and muscle power.

To investigate the effects of simultaneous explosive-strength and endurance training on physical performance characteristics, 10 experimental (E) and 8 control (C) endurance athletes trained for 9 wk. The total training volume was kept the same in both groups, but 32% of training in E and 3% in C was replaced by explosive-type strength training. A 5-km time trial (5K), running economy (RE), maximal 20-m speed (V20 m), and 5-jump (5J) tests were measured on a track. Maximal anaerobic (MART) and aerobic treadmill running tests were used to determine maximal velocity in the MART (VMART) and maximal oxygen uptake (VO2 max). The 5K time, RE, and VMART improved (P < 0.05) in E, but no changes were observed in C. V20 m and 5J increased in E (P < 0.01) and decreased in C (P < 0.05). VO2 max increased in C (P < 0.05), but no changes were observed in E. In the pooled data, the changes in the 5K velocity during 9 wk of training correlated (P < 0.05) with the changes in RE [O2 uptake (r = -0.54)] and VMART (r = 0.55). In conclusion, the present simultaneous explosive-strength and endurance training improved the 5K time in well-trained endurance athletes without changes in their VO2 max. This improvement was due to improved neuromuscular characteristics that were transferred into improved VMART and running economy.

Adult↗

PubMed2000

Reliability and running speed effects of in-shoe loading measurements during slow treadmill running.

In-shoe measurement systems allow the clinician and researcher to examine the loading parameters within the shoe. This study sought to investigate the test retest reliability and speed effects of in-shoe loading parameters using the Pedar System (Novel GMBH Munich) during slow treadmill running. The results indicated good to excellent test retest reliability between the two days test-Intraclass correlation coefficients (ICC's) ranged from 0.84-0.99 depending on the plantar region and variable analyzed. All plantar loading variables increased (peak pressure, peak pressure time impulse, peak force, and force time impulse) with the exception of contact area when treadmill running speed was increased from 2.24 m/s to 3.13 m/s. Results indicate that control of running speed is essential in obtaining reproducible data using this system to measure in-shoe loading data.

Adult↗

PubMed2000

Running hamster: a new type of mutant characterized as speedy, rotative running without motor and balance deficits.

Running hamster OYC (RHO) is a mutant spontaneously arisen in a closed colony of Armenian Hamsters and has a characteristic of speedy, rotative running behavior. There are several reports which describe such mutants as abnormal walking behavior in rodents due to ataxia or balance deficits. In this report, we describe results of several motor and balance tests in order to clarify whether or not RHO mutants have such disorders. RHO mutants showed no sign of either motor or auditory deficits, and scarcely had balance deficits tested. The animals only had slight head tilting at the starting of running. These results suggest that RHO is a really new type of mutant which has not previously been reported.

Animals↗

PubMed1977

[Long-term study on the influence of running exercise, food restriction, running exercise + food restriction and of parenterally applicated testis cells on age-parameters of the rat (author's transl)].

Preliminary results of a long-term study on 1100 male Sprague-Dawley rats are presented, showing the influence of running exercise, of restricted diet, of both of these together and of the s.c. application of lypholized testis cells. Up to now animals aged 9, 15 and 24 mths were investigated. The test-animals were exposed to the experimental conditions from their 6th month of life. The running exercise was carried out on a treadmill (30 m at a speed of 25 m/min, horizontal) 5 days a week. A food restriction of about 20% was achieved by 2 fasting-days a week. The lyophilized testis cells were injected for the first time at an age of 9 mths and afterwards in 6 mths intervals. Between the injection and the assessment of the age-parameters there was an interval of 6 mths. S o fare the following parameters of the comprehensive test-program have been evaluated: 1) running performance in m (treadmill, 20 m/min, ascent 15 degrees), 2) motor activity (Animex Activity Meter), 3) chemical contraction-relaxation of tail-tendon-fibers, 4) total lipids and total cholesterol in the plasma. The results obtained so far show that a mild regular training, moderate food restriction and the s.c. application of testis-cells are able to cause a significant shift in the dirction of a younger biological age in at least some of the age parameters. The action of the testis-cells seems to affect most of the age parameters but shows the tendency to be more distinct at a higher age. More concrete statements about the influence on the biological age or the vitality will only be possible after the multivariate analysis of the results.

Age Factors↗