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At least 1,225 records · Page 68Linked to original sources

PubMed1988

Vigorous exercise in a female with cystic fibrosis: spirometric, biochemical, and endocrine responses during four types of intensive exercise.

Spirometric, biochemical, and endocrine responses during a maximal ergometer cycle test and during three runs (10 km, 21.1 km, and 42.2 km) were investigated in one female with cystic fibrosis (CF) 27 years of age and in two healthy control females 26 and 29 years of age. One of the controls ran as a companion to the CF woman, while the other ran at her own speed. The CF woman has a chronic respiratory Pseudomonas aeruginosa infection, and her spirometric values were 50%-70% of predicted values at the time of the study. For the last years she has been training almost daily with aerobics, running, cycling, or skiing. She completed the four types of exercise without major problems. Her spirometric values increased transiently following the cycle test and for several hours following the three races (maximal 20%-30% increase of spirometric values), while the controls had transient decreases of the same variables in response to the runs. The biochemical and the hormonal changes were similar in the CF woman and the control who ran at her own speed, while the control who was a less stressed companion showed smaller changes. This study demonstrates that well-trained females with CF may participate in strenuous prolonged exercise without untoward effects.

Adrenal Cortex Hormones↗

PubMed1980

Effect of exercise on aging--effect of aging on exercise.

The coincidence of age changes with alterations in body structure and function is striking. Increasing evidence indicates that many of the changes commonly attributable to aging can be retarded by an active exercise program. Physical exercise, properly supervised, is a safe and widely applicable form of therapy.

Aged↗

PubMed1976

Cardiac monitoring during exercise tests in the horse. 2. Heart rate responses to exercise.

Data on resting heart rates, pre-exercise heart rates, the anticipatory rises before exercise, the influence of speed of work and recovery heart rates have been presented. Some observations on differences in the heart rate response on slow and fast working days are also recorded. In conformity with other workers, a linear relationship between heart rate and working speed within the range of 400-800 metre/min was observed. When the speed of work was between 400-800 metre/min, horses with resting ECG's classed as abnormal had significantly higher heart rates than those regarded as normal. It was also observed that the abnormal animals showed lower heart rates than a small number classed as borderline. The significance of these findings is discussed and the need for further work indicated.

Animals↗

PubMed1988

Effects of prior exercise on the performance of intense isometric exercise.

The influence of a regimen designed to lower the muscle glycogen content on the capacity to perform a single brief isometric contraction has been studied. Eight male subjects performed a single exhausting isometric contraction of the knee extensor muscles at a tension corresponding to 60% of maximum voluntary contraction (MVC). This was followed by prolonged cycling exercise at a work rate equivalent to approximately 75% of maximum oxygen uptake in order to reduce the muscle glycogen content. A diet low in carbohydrate was consumed for the remainder of this day in order to retard the resynthesis of muscle glycogen. The isometric contraction at 60% of MVC was repeated on the following day. Endurance time on the first day was 53.8 +/- 8.4 s (mean +/- SD); this was reduced (45.8 +/- 12.1 s; p less than 0.02) on the second day. From previously published data on rates of muscle glycogen utilisation during isometric exercise, it seems probable that insufficient glycogen is available in the muscle under the low carbohydrate condition to enable maximum performance to be achieved.

Adult↗

PubMed2006

Reversibility of exercise-induced dendritic attenuation in brain cardiorespiratory and locomotor areas following exercise detraining.

It has been shown previously that dendritic branching in cardiorespiratory and locomotor brain areas can be attenuated with exercise training (ET). It was not known whether this process was reversible. Twenty-three (n = 23) male Sprague-Dawley rats were individually caged and divided into two groups: untrained (UN; n = 11) and detrained (DTR; n = 12). DTR were provided with a running wheel at 21 days of age and exercised spontaneously. After 120 days (70 days of ET followed by 50 days of detraining), ET indexes were obtained, including maximal oxygen uptake, percent body fat, resting heart rate, and heart weight-to-body weight ratios. The brain was processed according to a modified Golgi-Cox procedure. Impregnated neurons from the periaqueductal gray (PAG), posterior hypothalamic area (PH), nucleus of the tractus solitarius (NTS), and cuneiform nucleus (CfN) were examined in coronal sections. Neurons were traced using a camera lucida technique and analyzed using the Sholl concentric ring analysis of dendritic branching. t-Tests compared the mean number of intersections per neuron by grouping inner rings, outer rings, and total number of intersections per animal. There were no significant differences between UN and DTR in PH, PAG, CfN, and NTS in the inner rings, outer rings, and total number of intersections per animal. A separate group of animals was used to show that a training effect in the CfN and NTS was present at 56 days of ET. Our results show that dendritic attenuation resulting from 70 days of ET in PH, PAG, CfN, and NTS is completely reversed with 50 days of detraining.

Adaptation, Physiological↗

PubMed2004

Prior heavy-intensity exercise speeds VO2 kinetics during moderate-intensity exercise in young adults.

The effect of prior heavy-intensity warm-up exercise on subsequent moderate-intensity phase 2 pulmonary O2 uptake kinetics (tauVO2) was examined in young adults exhibiting relatively fast (FK; tauVO2 < 30 s; n = 6) and slow (SK; tauVO2 > 30 s; n = 6) VO2 kinetics in moderate-intensity exercise without prior warm up. Subjects performed four repetitions of a moderate (Mod1)-heavy-moderate (Mod2) protocol on a cycle ergometer with work rates corresponding to 80% estimated lactate threshold (moderate intensity) and 50% difference between lactate threshold and peak VO2 (heavy intensity); each transition lasted 6 min, and each was preceded by 6 min of cycling at 20 W. VO2 and heart rate (HR) were measured breath-by-breath and beat-by-beat, respectively; concentration changes of muscle deoxyhemoglobin (HHb), oxyhemoglobin, and total hemoglobin were measured by near-infrared spectroscopy (Hamamatsu NIRO 300). tauVO2 was lower (P < 0.05) in Mod2 than in Mod1 in both FK (20 +/- 5 s vs. 26 +/- 5 s, respectively) and SK (30 +/- 8 s vs. 45 +/- 11 s, respectively); linear regression analysis showed a greater "speeding" of VO2 kinetics in subjects exhibiting a greater Mod1 tauVO2. HR, oxyhemoglobin, and total hemoglobin were elevated (P < 0.05) in Mod2 compared with Mod1. The delay before the increase in HHb was reduced (P <0.05) in Mod2, whereas the HHb mean response time was reduced (P <0.05) in FK (Mod2, 22 +/- 3 s; Mod1, 32 +/- 11 s) but not different in SK (Mod2, 36 +/- 13 s; Mod1, 34 +/- 15 s). We conclude that improved muscle perfusion in Mod2 may have contributed to the faster adaptation of VO2, especially in SK; however, a possible role for metabolic inertia in some subjects cannot be overlooked.

Adaptation, Physiological↗

PubMed2005

Maximal metabolic rates during voluntary exercise, forced exercise, and cold exposure in house mice selectively bred for high wheel-running.

Selective breeding for high wheel-running activity has generated four lines of laboratory house mice (S lines) that run about 170% more than their control counterparts (C lines) on a daily basis, mostly because they run faster. We tested whether maximum aerobic metabolic rates (V(O2max)) have evolved in concert with wheel-running, using 48 females from generation 35. Voluntary activity and metabolic rates were measured on days 5+6 of wheel access (mimicking conditions during selection), using wheels enclosed in metabolic chambers. Following this, V(O2max) was measured twice on a motorized treadmill and twice during cold-exposure in a heliox atmosphere (HeO2). Almost all measurements, except heliox V(O2max), were significantly repeatable. After accounting for differences in body mass (S < C) and variation in age at testing, S and C did not differ in V(O2max) during forced exercise or in heliox, nor in maximal running speeds on the treadmill. However, running speeds and V(O2max) during voluntary exercise were significantly higher in S lines. Nevertheless, S mice never voluntarily achieved the V(O2max) elicited during their forced treadmill trials, suggesting that aerobic capacity per se is not limiting the evolution of even higher wheel-running speeds in these lines. Our results support the hypothesis that S mice have genetically higher motivation for wheel-running and they demonstrate that behavior can sometimes evolve independently of performance capacities. We also discuss the possible importance of domestication as a confounding factor to extrapolate results from this animal model to natural populations.

Age Factors↗

PubMed1976

Exercise London: a disaster exercise involving numerous casualties.

A large-scale disaster exercise was conducted to assess how one large community would handle such a situation - particularly, how it would deal with 150 casualties. The planning, undertaken by a subcommittee composed of representatives of all resource groups in the city, took more than a year. The deficiencies of the disaster plan detected during the exercise, which included a lack of trained personnel and various problems of communication, are now being corrected.

Communication↗

PubMed1990

[Judgement on students' exercise for resuscitation using a manikin for CPCR exercise (1st report)].

We performed the training for resuscitation using dental students and used a manikin for CPCR Exercise before and after the training to investigate the result obtained. The results were as follows. 1. Although cases in which too much or too little ventilation in amount was judged showed no significant changes before and after the training, those judged too much in ventilation amounted to approx. 1/5 and those judged too little were approx. 1/2 of the total subjects. This suggests that it is preferable to instruct the students to maintain sufficient ventilation when allowing them to exercise artificial breathing of CPCR. But the instruction is somewhat difficult to take because inhibition of gastric distention should be taken into account. 2. Although no changes were shown before and after the training by cases judged too deep in the depth of thoracic oppression, the number of those cases amounted to approx. 4/5 of the total subjects. Cases judged too shallow in depth of thoracic oppression, on the other hand, were significantly decreased from approx. 4/5 before training to approx. 2/3 after training, suggesting that improvement of the shallow oppression initially made is easy rather than to improve the oppression unduly deepened. Accordingly, it appears effective for students to avoid undue oppression when they are trained. 3. Thoracic oppression at a correct position was increased significantly to approx. 1/5 of the total cases, although most of the subjects were in error to choose a correct position for thoracic oppression before training.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiopulmonary Resuscitation↗

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↗

PubMed2026

Acute pre-exercise oral intake of cacao polyphenols attenuates central fatigue development during sustained low-intensity ankle dorsiflexion exercise in healthy young male adults.

This double-blind, randomized, crossover study investigated whether acute cacao polyphenol (CP) ingestion attenuates neuromuscular fatigue in 19 healthy young male adults. After consuming CP or placebo, participants performed sustained isometric ankle dorsiflexion at 25% of maximal voluntary isometric contraction (MVIC) torque until task failure. Neuromuscular function (MVIC torque, voluntary activation [VA%], doublet torque) and electromyographic activity were assessed before, immediately after, and during recovery (1 and 5 min). Salivary chromogranin A and α-amylase were measured at baseline and 1 min post-task. Only VA% and chromogranin A showed significant condition × time interactions (p = 0.027-0.039). VA% significantly decreased from before to immediately after the task and 1 min post-task in both conditions (p ≤ 0.002), with significantly higher values in the CP condition than in placebo immediately after and 1 min post-task (p ≤ 0.037). Chromogranin A significantly increased from baseline to 1 min post-task in the placebo condition (p < 0.001) but not in the CP condition (p = 0.083). These findings suggest that acute CP ingestion attenuates the decline in central motor drive and autonomic stress responses following strenuous exercise, without altering performance or peripheral recovery, supporting its potential as a nutritional strategy for modulating central fatigue.

Humans↗

PubMed2005

[Improving of muscle mass and force in rehabilitation of heart-lung patients. Aerobic interval training, resistance-exercises, excentric exercises, vibration].

Improvement of muscle mass and force which got depleted by inactivity or pathological processes is one of the aims and also a prerequisite of a rehabilitative intervention. Metabolically active larger and stronger muscles diminish the cardiovascular risk, permit the aerobic preventive and rehabilitative activities and enables a higher quality of life. Interval forms of aerobic exercise improves also the muscles. The resistance training plays an important part in rehabilitation. Beside the traditional dynamic strength training with weights, gym machines, body weight etc. the excentric type of muscle activity potentiates higher muscle load with lesser energy consumption, therefore it is suitable in the case of smaller performance ability. Vibration of the whole body or parts of it by machines improves the co-activity of the motor units and results in force development with small metabolic involvement.

Body Weight↗

PubMed1990

Exercise and arthritis. Exercise and the back.

Some of the positive benefits from participating in aerobic activity have already been addressed. However, an individual's ability to participate in many aerobic activities may be contingent on the ability to maintain a neutral or a stabilized spine. For example, the individual for whom jogging has been painful may be able to jog after he or she has learned trunk stabilization and is able to keep the spine in his or her pain-free position. Although Williams contended that jogging was an inappropriate activity for the individual with a low-back problem, contrary to this notion, White believes that jogging is more apt to protect a person from low-back pain than to cause it. Although no association was found between mileage run and osteoarthritis, jogging is not for all individuals who present with LBP or related arthritic conditions. Moreover, poor biomechanics in running can exacerbate existing low-back problems as well as bring about new ones as compensatory adaptations are made. For example, poor running technique might include excessive forward lean; this must be counterbalanced by contraction of the back extensors, which then may become overly tired or produce high intersegmental forces on the discs. We advocate an upright posture with minimal forward lean. The biomechanics of running also are most important from the perspective of shock absorption. Factors to consider in addition to running within the neutral spine excursion include cushioning footstrike by "giving" at the ankle, knee, and hip joints. In addition to good biomechanics, it would also be important to use an excellent quality training shoe and to run on a soft track as opposed to harder surfaces; hills should probably be avoided for most symptomatic individuals until they become strong. Nachemson indicates that in addition to recommending jogging for LBP, he most commonly recommends backstroke swimming, brisk walking, and stairclimbing. Bicycle riding (stationary or actual) would be another good activity; I personally endorse cross-country ski machines such as the NordicTrack (Chaska, Minnesota). The latter provides an excellent opportunity to develop aerobic conditioning without impact; moreover it incorporates the tenets of stabilization training because it is essential that the skier uses the abdominal muscles to brace and stabilize the trunk. Cross-country ski machines do, however, present certain coordination requirements to which not all individuals can adapt readily. In conclusion, although exercise is by no means a panacea, it very well may be nature's elixir that will enable some individuals beset by mechanical problems of the back to assume a more active and enjoyable life.

Arthritis↗

PubMed1984

Evaluating the cardiac patient for exercise therapy. Role of exercise testing.

Several types of exercise tests and their use are reviewed. Suggestions are made for modification of tests to enhance their value in the counseling of normal individuals and patients with cardiac problems regarding occupational, recreational, and training activity. Also discussed are indications and contraindications to testing, end points in testing, and evaluation of test results.

Arm↗

PubMed1993

Orthostasis: exercise and exercise training.

There are two major problems here that are not independent. One is the more practically oriented problem of determining the effect of various modes of exercise training on gravitational tolerances, i.e., the point of syncope (unconsciousness) usually estimated from the time of appearance of presyncopal signs and symptoms. The other is more theoretical and concerns the mechanism of blood pressure failure that results in syncope. In many experimental designs these two problems or purposes have been intermingled, with equivocal results.

Blood Pressure↗

PubMed1992

Effects of resistance and endurance exercise on bone mineral status of young women: a randomized exercise intervention trial.

A substantial body of cross-sectional data and a smaller number of intervention trials generally justify optimism that regular physical activity benefits the skeleton. We conducted an 8 month controlled exercise trial in a group of healthy college women (mean age = 19.9 years) who were randomly assigned to a control group or to progressive training in jogging or weight lifting. We measured the following variables: bone mineral density (BMD) of the spine (L2-4) and right proximal femur using dual-energy x-ray absorptiometry, dynamic muscle strength using the 1-RM method, and endurance performance using the 1.5 mile walk/run field test. A total of 31 women completed the 8 month study. For women completing the study, compliance, defined as the percentage of workout sessions attended, was 97% for the runners (range 90-100%) and 92% (range 88-100%) for the weight trainers. Body weight increased by approximately 2 kg in all groups (p less than 0.05). Weight training was associated with significant increases (p less than 0.01) in muscle strength in all muscle groups. Improvement ranged from 10% for the deep back to 54% for the leg. No significant changes in strength scores were observed in the control or running groups. Aerobic performance improved only in the running group (16%, p less than 0.01). Lumbar BMD increased (p less than 0.05) in both runners (1.3 +/- 1.6%) and weight trainers (1.2 +/- 1.8%). These results did not differ from each other but were both significantly greater than results in control subjects, in whom bone mineral did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗

PubMed1996

Local bone mineral density, muscle strength, and exercise in adolescent boys: a comparative study of two groups with different muscle strength and exercise levels.

The primary objective of the present study was to evaluate the impact of physical activity and muscle strength on bone mineral density (BMD) of the tuberositas tibiae in adolescent boys. Two groups with different exercise levels were compared. The high activity group consisted of 20 subjects (age 15.9 +/- 0.3) from a junior ice hockey team. The reference group consisted of 24 volunteers (age 15.9 +/- 0.3) not training for more than 3 hours per week. The groups were matched for age, weight, and pubertal stage. BMDs (g/cm2) of the tuberositas tibiae and proximal tibia were measured using dual energy X-ray absorptiometry. Quadriceps strength was significantly higher in the high activity group (P < 0.01). Univariate correlations were measured between tuberositas tibiae BMD and pubertal stage, weight, height, BMI, fat mass, lean body mass, quadriceps strength, and hamstrings strength in the high activity group and the reference group, respectively. Quadriceps strength was estimated to be the best significant predictor of BMD of the tuberositas tibiae in the reference group. A multivariate analysis confirmed this result. In the high activity group, there was no significant predictor of BMD of the tuberositas tibiae. There was no significant difference in BMD at this site when comparing the two groups. However, five of the boys in the high activity group had a former history of Mb Osgood-Schlatter with a significantly lower BMD of the tuberositas tibiae than the rest of the boys in that group. After exclusion of these boys, the remaining 15 boys were matched against 20 boys from the reference group using the previous criteria. These 15 boys then showed a significantly higher BMD of the tuberositas tibiae (P < 0.05) but not of the proximal tibia than the 20 boys in the reference group. In conclusion, this study demonstrates site-specific increments of tuberositas tibiae BMD in adolescent ice hockey players unless they are affected by the negative effects on BMD by Mb Osgood-Schlatter. These increments seem primarily to be associated with forceful muscle contractions related to high quadriceps strength and not greater weight-bearing loading. Muscle strength seems to positively affect BMD of the tuberositas tibiae in adolescents, but only up to a certain level, above which additional muscle strength has no effect.

Adolescent↗

PubMed1997

Energy expenditure using isotope-labelled water (2H218O), exercise performance, skeletal muscle enzyme activities and plasma biochemical parameters in humans during 95 days of endurance exercise with inadequate energy intake.

Two men, R.F. and M.S., pulled sledges each with starting masses of 222 kg, 2300 km across Antarctica. Exercise was performed for approximately 10 h each day for 95 days. Despite an average energy intake of 21.3 MJ.day-1 both subjects lost more than 25% of body weight. Energy expenditure was measured using energy balance data (EB) and isotope-labelled water (2H218O). Isotope doses were taken on day 0 and day 50 of the expedition. During the first 50 days both methods gave reasonable agreement, giving energy expenditures of 38.3 (EB) and 35.5 (2H218O) MJ.day-1 in R.F. and 28.6 (EB) and 29.1 (2H218O) MJ.day-1 in M.S. The isotope data for days 20-30 yielded exceptional values of 44.6 MJ.day-1 in R.F. and 48.7 MJ.day-1 in M.S. Estimates of energy expenditure between day 51 and day 96 were much lower and although the methods were in agreement for R.F.-24.1 (EB) and 23.1 (2H218O) MJ. day-1, there was poor agreement for MS-26.8 (EB) and 18.8 (2H218O) MJ.day-1. However, some practical difficulties occurred during this second period and there were also problems arising from marked increases in body water that made estimates of body mass and composition change difficult to interpret. The latter problems were probably due to malnutrition, which may have also been responsible for surprising increases in urinary excretion of 2H and 18O observed in both men at around day 81. These increases may reflect the release of label incorporated into molecules other than water which do not normally freely exchange with the body water pool under the circumstances of marked malnourishment. Following the expedition, both men showed declines in maximal O2 consumption (VO2max, 53.6 to 41.2 ml O2 kg-1.min-1 in R.F., 58.1-46.0 ml O2 kg-1.min-1 in M.S.); maximal voluntary isometric force production in different muscle groups (up to 19.9% in R.F. and 55.8% in M.S.) and both cytoplasmic and mitochondrial skeletal muscle enzyme activities (up to 56% in R.F. and 63% in M.S.). Plasma samples taken during the expedition showed low glucose levels, inappropriately high insulin levels, and declines in testosterone and luteinizing hormone. Thyroxine, cholesterol, albumin and triglyceride levels remained normal.

Adult↗