Downhill treadmill running trains the rat spinotrapezius muscle

2007 ◽  
Vol 102 (1) ◽  
pp. 412-416 ◽  
Author(s):  
S. A. Hahn ◽  
L. F. Ferreira ◽  
J. B. Williams ◽  
K. P. Jansson ◽  
B. J. Behnke ◽  
...  
Keyword(s):  
Citrate Synthase ◽  
Oxidative Capacity ◽  
Peak Oxygen Uptake ◽  
Microscopic Investigation ◽  
Treadmill Running ◽  
Whole Body ◽  
Initial Tension ◽  
Downhill Running ◽  
Health And Disease ◽  
Microcirculatory Function

There are currently no models of exercise that recruit and train muscles, such as the rat spinotrapezius, that are suitable for transmission intravital microscopic investigation of the microcirculation. Recent experimental evidence supports the concept that running downhill on a motorized treadmill recruits the spinotrapezius muscle of the rat. Based on these results, we tested the hypothesis that 6 wk of downhill running (−14° grade) for 1 h/day, 5 days/wk, at a speed of up to 35 m/min, would 1) increase whole body peak oxygen uptake (V̇o2 peak), 2) increase spinotrapezius citrate synthase activity, and 3) reduce the fatigability of the spinotrapezius during electrically induced 1-Hz submaximal tetanic contractions. Trained rats ( n = 6) elicited a 24% higher V̇o2 peak (in ml·min−1·kg−1: sedentary 58.5 ± 2.0, trained 72.7 ± 2.0; P < 0.001) and a 41% greater spinotrapezius citrate synthase activity (in μmol·min−1·g−1: sedentary 14.1 ± 0.7, trained 19.9 ± 0.9; P < 0.001) compared with sedentary controls ( n = 6). In addition, at the end of 15 min of electrical stimulation, trained rats sustained a greater percentage of the initial tension than their sedentary counterparts (control 34.3 ± 3.1%, trained 59.0 ± 7.2%; P < 0.05). These results demonstrate that downhill running is successful in promoting training adaptations in the spinotrapezius muscle, including increased oxidative capacity and resistance to fatigue. Since the spinotrapezius muscle is commonly used in studies using intravital microscopy to examine microcirculatory function at rest and during contractions, our results suggest that downhill running is an effective training paradigm that can be used to investigate the mechanisms for improved microcirculatory function following exercise training in health and disease.

Capillary tortuosity in rat soleus muscle is not affected by endurance training

1989 ◽  
Vol 256 (4) ◽  
pp. H1110-H1116 ◽  
Author(s):  
D. C. Poole ◽  
O. Mathieu-Costello ◽  
J. B. West
Keyword(s):  
Exercise Training ◽  
Citrate Synthase ◽  
Metabolic Response ◽  
Oxidative Capacity ◽  
Treadmill Running ◽  
Female Rats ◽  
Capillary Length ◽  
Direct Function ◽  
Musculus Soleus ◽  
Muscle Changes

The total capillary length available for blood-tissue transfer is determined by the number and orientation of the capillaries. Therefore, whether capillary tortuosity changes with exercise training has important implications for peripheral gas exchange. To determine the effects of exercise training on capillary orientation and capillary length per volume of muscle fiber [Jv(c,f)] female rats were trained by treadmill running (30 m/min, up to 60 min/day, 5 days/wk) for 4 wk. Muscles from control and trained rats were perfusion fixed at sarcomere lengths (l) ranging from 1.59 to 2.15 microns, and morphometric techniques were used to estimate capillary orientation and Jv(c,f). Training increased (P less than 0.05) musculus soleus oxidative capacity 35% [as estimated from citrate synthase activity: 24.7 +/- 1.4 to 34.7 +/- 1.0 (SE) mumol.g-1.min-1], capillary-to-fiber ratio 30% (2.17 +/- 0.06 to 2.83 +/- 0.05), and Jv(c,f) 32% (1,886 +/- 73 to 2,496 +/- 180 mm-2). Capillary tortuosity (as determined from comparisons of transverse and longitudinal sections) was a direct function of l in control and trained rats and contributed 17-73% of capillary length above that estimated from capillary counts on transverse sections. We conclude that capillary tortuosity in m. soleus is unchanged by training. Therefore, Jv(c,f) increases as a consequence of increased capillary number. M. soleus citrate synthase activity is best correlated with Jv(c,f) and not with capillary counts on transverse sections. We hypothesize that training-induced muscle changes of capillary geometry improve O2 delivery to skeletal muscle and may therefore alter the metabolic response (e.g., lactate accumulation) to exercise after training.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Muscle Oxidative Capacity Is a Better Predictor of Insulin Sensitivity than Lipid Status

2003 ◽  
Vol 88 (11) ◽  
pp. 5444-5451 ◽  
Author(s):  
Clinton R. Bruce ◽  
Mitchell J. Anderson ◽  
Andrew L. Carey ◽  
David G. Newman ◽  
Arend Bonen ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Citrate Synthase ◽  
Oxidative Capacity ◽  
Fatty Acyl ◽  
Whole Body ◽  
Before And After ◽  
Hydroxyacyl Coa Dehydrogenase ◽  
Long Chain

Abstract We determined whole-body insulin sensitivity, long-chain fatty acyl coenzyme A (LCACoA) content, skeletal muscle triglyceride (TGm) concentration, fatty acid transporter protein content, and oxidative enzyme activity in eight patients with type 2 diabetes (TYPE 2); six healthy control subjects matched for age (OLD), body mass index, percentage of body fat, and maximum pulmonary O2 uptake; nine well-trained athletes (TRAINED); and four age-matched controls (YOUNG). Muscle biopsies from the vastus lateralis were taken before and after a 2-h euglycemic-hyperinsulinemic clamp. Oxidative enzyme activities, fatty acid transporters (FAT/CD36 and FABPpm), and TGm were measured from basal muscle samples, and total LCACoA content was determined before and after insulin stimulation. Whole-body insulin-stimulated glucose uptake was lower in TYPE 2 (P &lt; 0.05) than in OLD, YOUNG, and TRAINED. TGm was elevated in TYPE 2 compared with all other groups (P &lt; 0.05). However, both basal and insulin-stimulated skeletal muscle LCACoA content were similar. Basal citrate synthase activity was higher in TRAINED (P &lt; 0.01), whereas β-hydroxyacyl CoA dehydrogenase activity was higher in TRAINED compared with TYPE 2 and OLD. There was a significant relationship between the oxidative capacity of skeletal muscle and insulin sensitivity (citrate synthase, r = 0.71, P &lt; 0.001; β-hydroxyacyl CoA dehydrogenase, r = 0.61, P = 0.001). No differences were found in FAT/CD36 protein content between groups. In contrast, FABPpm protein was lower in OLD compared with TYPE 2 and YOUNG (P &lt; 0.05). In conclusion, despite markedly elevated skeletal muscle TGm in type 2 diabetic patients and strikingly different levels of whole-body glucose disposal, both basal and insulin-stimulated LCACoA content were similar across groups. Furthermore, skeletal muscle oxidative capacity was a better predictor of insulin sensitivity than either TGm concentration or long-chain fatty acyl CoA content.

Muscle respiratory capacity and VO2 max in identically trained young and old rats

1987 ◽  
Vol 63 (1) ◽  
pp. 257-261 ◽  
Author(s):  
G. D. Cartee ◽  
R. P. Farrar
Keyword(s):  
Skeletal Muscle ◽  
Citrate Synthase ◽  
Treadmill Running ◽  
Whole Body ◽  
Vo2 Max ◽  
Respiratory Enzymes ◽  
Respiratory Capacity ◽  
Palmitate Oxidation ◽  
Age Related ◽  
Old Rats

Old rats have a decreased hindlimb muscle respiratory capacity and whole-body maximal O2 consumption (VO2 max). The decline in spontaneous physical activity in old rats might contribute to these age-related changes. The magnitude of the age-related decline is not uniform in all skeletal muscle respiratory enzymes, and the decrease in palmitate oxidation is particularly great. This study was designed to determine if young and old rats subjected to the same exercise-training protocol would attain similar values for VO2 max and several markers of muscle respiratory capacity. Four- and 18-mo-old Fischer 344 rats underwent an identical 6-mo program of treadmill running. After training, both age groups had increased VO2 max above sedentary age-matched controls. However, the old trained rats had a lower VO2 max than identically trained young rats. In contrast to VO2 max, the two trained groups attained similar values for gastrocnemius citrate synthase, cytochrome oxidase, 3-hydroxyacyl-CoA dehydrogenase, palmitate oxidation, and total carnitine concentration. Thus, when the young and old rats performed an identical exercise protocol within the capacity of the old animals, differences in skeletal muscle respiratory capacity were eliminated. The dissimilarity in VO2 max between the identically trained groups was apparently caused by age-related differences in factors other than muscle respiratory capacity.

Muscle-specific expression of PPARγ coactivator-1α improves exercise performance and increases peak oxygen uptake

2008 ◽  
Vol 104 (5) ◽  
pp. 1304-1312 ◽  
Author(s):  
Jennifer A. Calvo ◽  
Thomas G. Daniels ◽  
Xiaomei Wang ◽  
Angelika Paul ◽  
Jiandie Lin ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Exercise Performance ◽  
Mitochondrial Gene ◽  
Oxidative Capacity ◽  
Peak Oxygen Uptake ◽  
Whole Body ◽  
Peroxisome Proliferator ◽  
Sprint Training ◽  
Specific Expression

The induction of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), a key regulator of mitochondriogenesis, is well-established under multiple physical exercise regimens, including, endurance, resistance, and sprint training. We wanted to determine if increased expression of PGC-1α in muscle is sufficient to improve performance during exercise in vivo. We demonstrate that muscle-specific expression of PGC-1α improves the performance during voluntary as well as forced exercise challenges. Additionally, PGC-1α transgenic mice exhibit an enhanced performance during a peak oxygen uptake exercise test, demonstrating an increased peak oxidative capacity, or whole body oxygen uptake. This increased ability to perform in multiple exercise paradigms is supported by enhanced mitochondrial function as suggested by increased mitochondrial gene expression, mitochondrial DNA, and mitochondrial enzyme activity. Thus this study demonstrates that upregulation of PGC-1α in muscle in vivo is sufficient to greatly improve exercise performance under various exercise paradigms as well as increase peak oxygen uptake.

Progressive effect of endurance training on VO2 kinetics at the onset of submaximal exercise

1995 ◽  
Vol 79 (6) ◽  
pp. 1914-1920 ◽  
Author(s):  
S. M. Phillips ◽  
H. J. Green ◽  
M. J. MacDonald ◽  
R. L. Hughson
Keyword(s):  
Endurance Training ◽  
Citrate Synthase ◽  
Oxidative Capacity ◽  
Exponential Model ◽  
Work Rate ◽  
Whole Body ◽  
O2 Uptake ◽  
Oxidative Potential ◽  
Mean Response Time ◽  
Vo2 Kinetics

The rates of increase in O2 uptake (VO2) after step changes in work rate from 25 W to 60% of pretraining peak VO2 (VO2 peak) were measured at various times during an endurance training program (2 h/day at 60% pretraining VO2 peak). Seven untrained males [23 +/- 1 (SE) yr] performed a series of repeated step changes in work rate before training (PRE) and after 4 days (4D), 9 days (9D), and 30 days (30D) of training. VO2 kinetic responses were determined from breath-by-breath data averaged across four repetitions and analyzed using a two-component exponential model. Mean response time (time taken to reach 63% of steady-state VO2) was faster (P < 0.01) than PRE (38.1 +/- 2.6 s) at both 4D (34.9 +/- 2.4 s) and 9D (32.5 +/- 1.8 s) and was faster (P < 0.01) at 30D than at all other times (28.3 +/- 1.0 s). Blood lactate concentrations (after 6 min of cycling) were also lower at 4D and 9D than PRE (P < 0.01) and were lower at 30D than at all other times (P < 0.01). VO2 peak was unchanged from PRE (3.52 +/- 0.20 l/min) at 8D (3.55 +/- 0.20 l/min) but was increased (P < 0.01) at 30D (3.89 +/- 0.18 l/min). Muscle oxidative capacity (maximal citrate synthase activity) was not significantly increased until 30D (P < 0.01). It is concluded that at least part of the acceleration of whole body VO2 kinetics with endurance training is a rapid phenomenon, occurring before changes in VO2 peak and/or muscle oxidative potential.

Effects of repetitive exercise on neonatal rat skeletal muscle oxidative capacity

1983 ◽  
Vol 54 (2) ◽  
pp. 530-535 ◽  
Author(s):  
A. M. MacIntosh ◽  
K. M. Baldwin
Keyword(s):  
Skeletal Muscle ◽  
Citrate Synthase ◽  
Maximal Oxygen Consumption ◽  
Oxidative Capacity ◽  
Treadmill Running ◽  
Neonatal Rat ◽  
Female Rats ◽  
Adult Rats ◽  
Male And Female Rats ◽  
Time Point

Since little is known about the training response to exercise in neonatal animals, this study was undertaken to elucidate the potential of oxidative system adaptations in developing skeletal muscle of rats during 50 days of daily treadmill running. The training regimen involved male and female rats (10 days old) initially running 0.1 mph, 0% grade, for 15 min. The program progressed to 1 mph, 25% grade, for 60 min by 50 days of age. At 25 days of age, pyruvate and palmitate oxidative capacity, and citrate synthase activity in red vastus muscle homogenates were elevated in the trained group (T) compared with age- and sex-matched controls (C). These increases were also observed for each subsequent time point tested and occurred in spite of the fact that the peak oxidative capacity of neonatal red vastus muscle was 46% greater than adult values. Further, trained animals tested at 45 days of age responded with a 12% increase in maximal oxygen consumption (Vo2max) compared with controls (P less than 0.05). Assays of muscle phosphofructokinase and of creatine phosphokinase activity conducted at this time point revealed no difference between T and C groups. Collectively, these data suggest that neonatal rats can be successfully trained and that they respond to an endurance-type program qualitatively similarly to adult rats.

Effect of hypokinesia-hypodynamia on rat muscle oxidative capacity and glucose uptake

1985 ◽  
Vol 249 (3) ◽  
pp. R308-R312 ◽  
Author(s):  
R. D. Fell ◽  
J. M. Steffen ◽  
X. J. Musacchia
Keyword(s):  
Insulin Sensitivity ◽  
Cytochrome C ◽  
Glucose Uptake ◽  
Citrate Synthase ◽  
Contractile Activity ◽  
Oxidative Capacity ◽  
Whole Body ◽  
Hindlimb Muscles ◽  
Muscle Disuse ◽  
Gastrocnemius Muscles

Whole-body hypokinetic-hypodynamic (H/H) suspension, unlike other models of muscle disuse, allows voluntary contractile activity. This study examined the oxidative capacity and insulin sensitivity of rat hindlimb muscles subjected to 7 days of suspension H/H conditions. Oxidative capacity was determined by measuring citrate synthase activity and cytochrome c concentration in soleus and gastrocnemius muscles. A perfused hindquarter preparation was used to measure glucose uptake rates at rest with physiological and supramaximal concentrations of insulin in the perfusate. Citrate synthase activity was 17% lower in soleus and 23% lower in gastrocnemius muscles from H/H rats. Similarly, a 29% decrease in H/H rat gastrocnemius cytochrome c concentration was observed. Rates of glucose uptake were lower in muscles from H/H rats compared with controls at physiological levels of insulin and did not increase in response to a further increase in insulin concentration. Muscles undergoing a significant loss in mass after 7 days suspension were found to have increased glycogen concentrations. In conclusion, data presented in this study suggest that hindlimb muscle disuse, brought about by whole-body suspension, results in a decreased aerobic capacity in load bearing muscles and a lowered insulin sensitivity in perfused rat hindlimb muscles.

scholarly journals Endurance Is Improved in Female Rats After Living High-Training High Despite Alterations in Skeletal Muscle

2021 ◽  
Vol 3 ◽  
Author(s):  
Alexandra Malgoyre ◽  
Alexandre Prola ◽  
Adelie Meunier ◽  
Rachel Chapot ◽  
Bernard Serrurier ◽  
...  
Keyword(s):  
High Altitude ◽  
Citrate Synthase ◽  
Oxidative Capacity ◽  
Female Rats ◽  
Whole Body ◽  
Aerobic Performance ◽  
Time To Exhaustion ◽  
Altitude Training ◽  
Similar Reduction ◽  
Mitochondrial Mass

Altitude camps are used during the preparation of endurance athletes to improve performance based on the stimulation of erythropoiesis by living at high altitude. In addition to such whole-body adaptations, studies have suggested that high-altitude training increases mitochondrial mass, but this has been challenged by later studies. Here, we hypothesized that living and training at high altitude (LHTH) improves mitochondrial efficiency and/or substrate utilization. Female rats were exposed and trained in hypoxia (simulated 3,200 m) for 5 weeks (LHTH) and compared to sedentary rats living in hypoxia (LH) or normoxia (LL) or those that trained in normoxia (LLTL). Maximal aerobic velocity (MAV) improved with training, independently of hypoxia, whereas the time to exhaustion, performed at 65% of MAV, increased both with training (P = 0.009) and hypoxia (P = 0.015), with an additive effect of the two conditions. The distance run was 7.98 ± 0.57 km in LHTH vs. 6.94 ± 0.51 in LLTL (+15%, ns). The hematocrit increased &gt;20% with hypoxia (P &lt; 0.001). The increases in mitochondrial mass and maximal oxidative capacity with endurance training were blunted by combination with hypoxia (−30% for citrate synthase, P &lt; 0.01, and −23% for Vmax glut−succ, P &lt; 0.001 between LHTH and LLTL). A similar reduction between the LHTH and LLTL groups was found for maximal respiration with pyruvate (−29%, P &lt; 0.001), for acceptor-control ratio (−36%, hypoxia effect, P &lt; 0.001), and for creatine kinase efficiency (−48%, P &lt; 0.01). 3-hydroxyl acyl coenzyme A dehydrogenase was not altered by hypoxia, whereas maximal respiration with Palmitoyl-CoA specifically decreased. Overall, our results show that mitochondrial adaptations are not involved in the improvement of submaximal aerobic performance after LHTH, suggesting that the benefits of altitude camps in females relies essentially on other factors, such as the transitory elevation of hematocrit, and should be planned a few weeks before competition and not several months.

Growth hormone enhances effects of endurance training on oxidative muscle metabolism in elderly women

2000 ◽  
Vol 279 (5) ◽  
pp. E989-E996 ◽  
Author(s):  
Kai Henrik Wiborg Lange ◽  
Fredrik Isaksson ◽  
Anders Juul ◽  
Michael Højby Rasmussen ◽  
Jens Bülow ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Endurance Training ◽  
Body Fat ◽  
Citrate Synthase ◽  
Elderly Women ◽  
Serum Insulin ◽  
Oxidative Capacity ◽  
Peak Oxygen Uptake ◽  
Oxidative Enzymes ◽  
Healthy Elderly

The present study investigated whether recombinant human (rh) growth hormone (GH) combined with endurance training would have a larger effect on oxidative capacity, metabolism, and body fat than endurance training alone. Sixteen healthy, elderly women, aged 75 yr, performed closely monitored endurance training on a cycle ergometer over 12 wk. rhGH was given in a randomized, double-blinded, placebo-controlled design in addition to the training program. GH administration resulted in a doubling of serum insulin-like growth factor I levels. With endurance training, peak oxygen uptake increased by ∼18% in both groups, whereas the marked increase in muscle citrate synthase activity was 50% larger in the GH group compared with the placebo group. In addition, only the GH group revealed an increase in musclel-3-hydroxyacyl-CoA dehydrogenase activity. Body weight remained unchanged in both groups, but the GH group showed significant changes in body composition with a decrease in fat mass and an increase in lean body mass. Twenty-four-hour indirect calorimetry performed in four subjects showed a marked increase in energy expenditure with increased relative and absolute fat combustion in the two subjects receiving rhGH. In conclusion, rhGH adds to the effects of endurance training on muscle oxidative enzymes and causes a reduction in body fat in elderly women.

GENDER COMPARISON OF PEAK OXYGEN UPTAKE: REPETITIVE LIFTING VS. TREADMILL RUNNING

1995 ◽  
Vol 27 (Supplement) ◽  
pp. S162
Author(s):  
B. C. Nindl ◽  
M. A. Sharp ◽  
R. P. Mello ◽  
V. J. Rice ◽  
J. F. Patton
Keyword(s):  
Oxygen Uptake ◽  
Peak Oxygen Uptake ◽  
Treadmill Running ◽  
Gender Comparison ◽  
Repetitive Lifting
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