Effects of exercise frequency, intensity, and duration on revascularization in the transition zone of infarcted rat hearts

In the rat model of chronic myocardial infarction the border or "transition zone," extending 225–525 μm from the margin of the scar, is supplied by significantly fewer capillaries and characterized by an altered capillary-fiber geometry when compared with healthy rat myocardium. Four weeks of daily voluntary running can, under certain conditions, promote capillary growth and a shift in capillary-fiber geometry, such that a normal capillary supply is restored to the transition zone. However, the importance of exercise frequency, intensity, and duration for capillary growth in the transition zone has not been determined. One week after surgical occlusion of the left coronary artery, rats were divided into four groups following different protocols of voluntary exercise (running): A (2 h/day, 6 days/week for 4 weeks), B (2 h/day, 3 days/week for 4 weeks), C (2 h/day, 6 days/week for 2 weeks, followed by 2 weeks sedentary), and D (2 h/day, 6 days/week for 2 weeks). Significant improvements in capillary supply to the transition zone were associated with voluntary exercise, three separate factors being of importance, (i) An intermediate total distance run; rats that ran 5–10 km in the month restored a normal number of capillaries and a normal capillary-fiber geometry in the transition zone, whereas rats that ran either <5 or >10 km showed no significant improvements. (ii) A balance between exercise frequency and mean distance ran per 2-h exercise period; rats in group B (3 days/week) had to run twice the daily distance of those in group A (6 days/week) to obtain the same improvement in capillary supply. (iii) Regular reinforcement of the exercise periods throughout the experiment; animals in groups B and D demonstrated significant increases in capillary supply in the transition zone, while those in group C did not. Although exercise stimulates capillary growth and a shift in capillary-fiber geometry in the transition zone, the mechanisms underlying these improvements are, as yet, unknown.

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Can exercise promote revascularization in the transition zone of infarcted rat hearts?

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y84-102 ◽

1984 ◽

Vol 62 (6) ◽

pp. 630-633 ◽

Cited By ~ 4

Author(s):

K. Przyklenk ◽

A. C. Groom

Keyword(s):

Coronary Artery ◽

Transition Zone ◽

Recovery Period ◽

Oxygen Demand ◽

Coronary Artery Occlusion ◽

Artery Occlusion ◽

Voluntary Exercise ◽

Border Zone ◽

Normal Number ◽

Rat Hearts

A border or transition zone, comprising muscle fibers supplied by fewer capillaries than normal, and characterized by an altered capillary – fiber geometry, is present as long as 5 weeks following coronary artery occlusion in the rat. This zone, which extends 225 – 525 μm laterally from the margin of the necrosis, may be at risk of becoming hypoxic, especially under conditions of increased oxygen demand. Our objective was to determine whether exercise can stimulate capillary growth in this transition zone. Myocardial infarcts were induced in rats by ligating the left coronary artery, midway between its origin and the apex of the heart. After a 1-week recovery period, the animals underwent 4 weeks of voluntary exercise, 2 h/day, 6 days/week. Rats which had run a total distance of 5 – 10 km during the month had both a normal number of capillaries and normal capillary–fiber geometry in the transition zone. In contrast, rats that ran either less than 5 km or more than 10 km during the 4 weeks showed no significant improvement in the number of capillaries or capillary – fiber geometry within the border zone. Thus, under certain conditions, exercise can promote revascularization in the transition zone of infarcted rat hearts.

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Calcineurin Is Activated in Rat Hearts With Physiological Left Ventricular Hypertrophy Induced by Voluntary Exercise Training

Circulation ◽

10.1161/01.cir.101.18.2134 ◽

2000 ◽

Vol 101 (18) ◽

pp. 2134-2137 ◽

Cited By ~ 42

Author(s):

Yoko Eto ◽

Katsunori Yonekura ◽

Makoto Sonoda ◽

Naoto Arai ◽

Masataka Sata ◽

...

Keyword(s):

Exercise Training ◽

Left Ventricular Hypertrophy ◽

Ventricular Hypertrophy ◽

Left Ventricular ◽

Voluntary Exercise ◽

Rat Hearts

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Microvascular evidence for a transition zone around a chronic myocardial infarct in the rat

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y83-217 ◽

1983 ◽

Vol 61 (12) ◽

pp. 1516-1522 ◽

Cited By ~ 8

Author(s):

K. Przyklenk ◽

A. C. Groom

Keyword(s):

Coronary Artery ◽

Transition Zone ◽

Myocardial Infarct ◽

Muscle Fibers ◽

Young Male ◽

Coronary Artery Occlusion ◽

Capillary Density ◽

Artery Occlusion ◽

Male Rats ◽

Capillary Supply

Muscle fibers in the transition zone of an infarcted heart are thought to be potentially ischemic during the first 6–9 h following coronary artery occlusion. However, the long-term fate of the muscle fibers at the margin of the necrosis is uncertain. Ischemia implies reduced oxygenation, possibly owing to a reduced capillary supply; thus our objective was to determine whether a region of reduced microvascular supply exists at the margin of a necrosis produced by chronic coronary artery occlusion. Five variables were used to quantitate the capillary supply in the transition zone: C/F (capillary to fiber) ratio, Vf (number of vessels around a fiber), Fv (number of fibers surrounding a vessel), capillary density, and fiber diameter. Infarcts were induced in young male rats by ligating the left coronary artery midway between its origin and the apex of the heart. Five weeks later, the capillary supply in the transition zone was significantly below control values, i.e., significant reductions in C/F, Vf, and Fv were found. This region of reduced capillary supply extended 225–525 μm laterally from the edge of the necrosis. Thus, a narrow transition zone, defined as a region of viable muscle fibers with a subnormal microvascular supply, exists as long as 5 weeks following coronary artery occlusion in the rat.

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Reliability and Validity of Questions About Exercise in the Canadian Study of Health and Aging

International Psychogeriatrics ◽

10.1017/s1041610202008128 ◽

2001 ◽

Vol 13 (S1) ◽

pp. 177-182 ◽

Cited By ~ 31

Author(s):

Heather S. Davis ◽

Kathleen MacPherson ◽

Heather R. Merry ◽

Carolyn Wentzel ◽

Kenneth Rockwood

Keyword(s):

Proportional Hazards ◽

Reliability And Validity ◽

Exercise Group ◽

Cox Proportional Hazards ◽

Regular Exercise ◽

Canadian Study ◽

Exercise Frequency ◽

Important Relationship ◽

Intraclass Correlations ◽

Frequency Intensity

Regular exercise in elderly people has beneficial health effects. We examined exercise frequency and intensity from the Canadian Study of Health and Aging Risk Factor Questionnaire (RFQ). The reliability and validity of these two questions individually, and when combined to form a scale, are reported. Agreement between the self-administered RFQ and an interviewer-administered Add-on Study was examined using intraclass correlations, which were 0.80 for frequency (95% CI 0.77-0.82, p < .001) and 0.75 for intensity (95% CI 0.71-0.78, p = .012). Individuals reporting high levels of exercise frequency, intensity, and a combination of the two showed a smaller proportion of adverse health markers than those reporting no regular exercise. Predictive validity assessed by Cox proportional hazards modeling of mortality showed that the high and moderate levels of frequency, intensity, and combined exercise groups differed significantly (all p < .001) from the no exercise group. We have found that these exercise questions, though simple, appear reliable and valid. The finding that even comparatively crude exercise questions can demonstrate an important relationship to death suggests that the signal for exercise is a strong one, and future studies should seek to better examine mechanisms by which exercise benefit is conferred.

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Influence of exercise and heat stress on pulmonary function during ozone exposure

Journal of Applied Physiology ◽

10.1152/jappl.1977.43.3.409 ◽

1977 ◽

Vol 43 (3) ◽

pp. 409-413 ◽

Cited By ~ 30

Author(s):

L. J. Folinsbee ◽

S. M. Horvath ◽

P. B. Raven ◽

J. F. Bedi ◽

A. R. Morton ◽

...

Keyword(s):

Heat Stress ◽

Pulmonary Function ◽

Exposure Period ◽

Ozone Exposure ◽

Wet Bulb Globe Temperature ◽

Exercise Period ◽

Maximum Expiratory Flow ◽

Group A ◽

Globe Temperature ◽

Group B

We studied the effects of a 2-h exposure to ozone (0.5 ppm) in 14 nonsmoking males under four environmental conditions (WBGT (wet bulb-globe temperature index) = 64.4, 80.0, 85.2, and 92.0 degrees F). The subjects were divided into two groups, A (n = 8) and B (n = 6). Thirty minutes of exercise at 40% Vo2 max was performed from 60 to 90 min for group A and 30 to 60 min for group B. Pulmonary function changes, determined throughout exposure, were greatest immediately after exercise in both groups. Few changes occurred before the exercise period. However, the decrease in FVC (826 ml) and FEV1.0 (937 ml) following exercise was more than twice as large as the decrement seen at end exosure (388 and 423 ml, respectively). Measures of maximum expiratory flow (FEF 25–75%, FEF 50% FEF 75%) showed similar reductions. In many cases, reversal of these changes occurred during the remainder of the exposure period. The greatest decrease in FVC occurred when heat and ozone exposures were combined (WBGT = 92.0 degrees F). We conclude that the effects of ozone are most severe immediately after exercise and that heat stress may modify the overall effect of ozone on pulmonary function.

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Relation between Voluntary Exercise Frequency and Cardiac Function in Dilated Cardiomyopathy Model Mice

Biophysical Journal ◽

10.1016/j.bpj.2017.11.789 ◽

2018 ◽

Vol 114 (3) ◽

pp. 140a

Author(s):

Masami Sugihara ◽

Ryo Kakigi ◽

Takashi Murayama ◽

Takashi Miida ◽

Takashi Sakurai ◽

...

Keyword(s):

Cardiac Function ◽

Dilated Cardiomyopathy ◽

Voluntary Exercise ◽

Exercise Frequency

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Impact of Effective Frequency Jack-knife Stretching on Preadolescent Male Football Players -Prospective Cohort Study-

10.21203/rs.3.rs-137911/v1 ◽

2021 ◽

Author(s):

Junsuke Nakase ◽

Kentaro Sasaki ◽

Kengo Shimozaki ◽

Kazuki Asai ◽

Ryota Muramatsu ◽

...

Keyword(s):

Body Mass Index ◽

Football Players ◽

Sitting Position ◽

Effective Frequency ◽

Exercise Frequency ◽

Level Of Evidence ◽

Straight Leg Raising ◽

Group A ◽

Hamstring Flexibility ◽

Group B

Abstract Objective: We aimed to investigate the effective frequency of jack-knife stretching in preadolescent male football players. Methods: We enrolled 47 male preadolescent football players (average age: 12.4 ± 0.6 years old). All participants took surveys at baseline and after intervention for 6 months. The survey items were height, weight, body mass index, anteflexion in sitting, and quadriceps and hamstring tightness. The participants were divided into two groups according to the stretching exercise frequency, where group A performed stretching at least once every 3 days and group B performed stretching less than once every 3 days. After exclusion, 17 participants were enrolled in each group.Results: There was a significant increase in anteflexion in the sitting position in group A but not group B; moreover, straight leg raising was significantly larger in Group AConclusions: Performing jack-knife stretching at least once every 3 days’ intervals could improve hamstring flexibility in preadolescent male football players.Level of Evidence Level Ⅱ

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Exercise Dimensions and Psychological Well-Being: A Community-Based Exercise Study

Journal of Clinical Sport Psychology ◽

10.1123/jcsp.2017-0027 ◽

2017 ◽

Vol 11 (2) ◽

pp. 107-125 ◽

Cited By ~ 6

Author(s):

Maggie Evans ◽

Kelly J. Rohan ◽

Alan Howard ◽

Sheau-Yan Ho ◽

Patricia M. Dubbert ◽

...

Keyword(s):

Psychological Health ◽

Mixed Model ◽

Linear Mixed Model ◽

Well Being ◽

Future Research ◽

Exercise Frequency ◽

Psychological Well Being ◽

Psychological Constructs ◽

Weight Satisfaction ◽

Frequency Intensity

This prospective, naturalistic study examined the relationship between different exercise dimensions (i.e., frequency, intensity, duration, and omissions of planned exercise) and psychological well-being among community adults participating in self-selected exercise. For at least 2 months, participants kept daily exercise diaries and provided weekly ratings for depressed mood, anxiety, sleep quality, concentration, alertness, confidence, weight satisfaction, physical fitness, appetite, satisfaction with physical shape and appearance, and stress experienced. Linear mixed model analyses revealed positive associations between exercise frequency, intensity, and duration across a broad range of psychological and mood-related outcomes. In contrast, omissions of planned exercise were associated with a global and detrimental effect on psychological health. A main effect of age and a moderating effect of gender was observed in many of the models. This work contributes to literature on exercise dimensions and psychological constructs and informs future research that is needed to develop physical activity recommendations for improved mental health.

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Coexistence of potentiation and low-frequency fatigue during voluntary exercise in human skeletal muscle

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y03-114 ◽

2003 ◽

Vol 81 (12) ◽

pp. 1092-1100 ◽

Cited By ~ 35

Author(s):

J R Fowles ◽

H J Green

Keyword(s):

High Frequency ◽

Isometric Exercise ◽

Low Frequency ◽

Voluntary Contraction ◽

Voluntary Exercise ◽

Moderate Intensity ◽

Twitch Force ◽

Leg Extension ◽

Exercise Period ◽

Low Frequency Fatigue

The role of muscle potentiation in overcoming low-frequency fatigue (LFF) as it developed during submaximal voluntary exercise was investigated in eight males (age 26.4 ± 0.7 years, mean ± SE) performing isometric leg extension at ~30% of maximal voluntary contraction for 60 min using a 0.5-duty cycle (1 s contraction, 1 s rest). At 5, 20, 40, and 60 min, exercise was interrupted for 3 min, and the maximum positive rate of force development (+dF/dtmax) and maximal twitch force (Pt) were measured in maximal twitch contractions at 0, 1, 2, and 3 min of rest (R0, R1, R2, R3); they were also measured at 15 min of recovery following the entire 60-min exercise period. These measures were compared with pre-exercise (PRE) as an indicator of potentiation. Force at low frequency (10 Hz) was also measured at R0, R1, R2, and R3, and at 15 min of recovery, while force at high frequency (100 Hz) was measured only at R0 and R3 and in recovery. Voluntary exercise increased twitch +dF/dtmax at R0 following 5, 20, 40, and 60 min of exercise, from 2553 ± 150 N/s at PRE to 39%, 41%, 42%, and 36% above PRE, respectively (P < 0.005). Twitch +dF/dtmax decayed at brief rest (R3) following 20, 40, and 60 min of exercise (P < 0.05). Pt at R0 following 5 and 20 min of exercise was above that at PRE (P < 0.05), indicating that during the early phase of moderate- intensity repetitive exercise, potentiation occurs in the relative absence of LFF. At 40 and 60 min of exercise, Pt at R0 was unchanged from PRE. The LFF (10 Hz) induced by the protocol was evident at 40 and 60 min (R0–R3; P < 0.05) and at 15 min following exercise (P < 0.05). High-frequency force was not significantly compromised by the protocol. Since twitch force was maintained, these results suggest that as exercise progresses, LFF develops, which can be compensated for by potentiation.Key words: excitability, myosin light chain, phosphorylation, isometric exercise.

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