Skeletal muscle structural and energetic characteristics in subjects with sickle cell trait, α-thalassemia, or dual hemoglobinopathy

2010 ◽  
Vol 109 (3) ◽  
pp. 728-734 ◽  
Author(s):  
Lucile Vincent ◽  
Léonard Féasson ◽  
Samuel Oyono-Enguéllé ◽  
Viviane Banimbek ◽  
Géraldine Monchanin ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sickle Cell ◽  
Power Output ◽  
Citrate Synthase ◽  
Sickle Cell Trait ◽  
Fiber Type ◽  
Time To Exhaustion ◽  
Fiber Types ◽  
Maximal Power ◽  
Maximal Power Output

Previous studies have shown that subjects with sickle cell trait (SCT), α-thalassemia (α-t), and the dual hemoglobinopathy (SCT/α-t) manifest subtle, albeit significant, differences during exercise. To better understand such differences, we assessed skeletal muscle histomorphological and energetic characteristics in 10 control HbAA subjects (C), 5 subjects with α-t (α-t), 6 SCT carriers (SCT) and 9 SCT carriers with α-t (SCT/α-t). Subjects underwent a muscle biopsy and also performed an incremental maximal exercise and a time to exhaustion test. There were no observable differences in daily energy expenditure, maximal power output (Pmax), or time to exhaustion at 110% Pmax ( Tex) among the groups. Blood lactate concentrations measured at the end of the Tex, muscle fiber type distribution, and mean phosphofructokinase (PFK), lactate dehydrogenase (LDH), β-hydroxyacyl-CoA-dehydrogenase (HAD), and citrate synthase (CS) activities were all similar among the four groups. However, SCT was associated with a lower cytochrome- c oxidase (COx) activity in type IIa fibers ( P < 0.05), and similar trends were observed in fiber types I and IIx. Trends toward lower creatine kinase (CK) activity ( P = 0.0702) and higher surface area of type IIx fibers were observed in SCT ( P = 0.0925). In summary, these findings support most of the previous observations in SCT, such as 1) similar maximal power output and associated maximal oxygen consumption (V̇o2max) values and 2) lower exercise performances during prolonged submaximal exercise. Furthermore, performances during short supramaximal exercise were not different in SCT. Finally, the dual hemoglobinopathy condition does not seem to affect muscle characteristics.

Power output and fatigue of human muscle in maximal cycling exercise

1983 ◽  
Vol 55 (1) ◽  
pp. 218-224 ◽  
Author(s):  
N. McCartney ◽  
G. J. Heigenhauser ◽  
N. L. Jones
Keyword(s):  
Power Output ◽  
Fiber Type ◽  
Average Power ◽  
Lactate Concentration ◽  
Peak Torque ◽  
Muscle Volume ◽  
Thigh Muscle ◽  
Peak Power Output ◽  
Maximal Power ◽  
Maximal Power Output

We studied maximal torque-velocity relationships and fatigue during short-term maximal exercise on a constant velocity cycle ergometer in 13 healthy male subjects. Maximum torque showed an inverse linear relationship to crank velocity between 60 and 160 rpm, and a direct relationship to thigh muscle volume measured by computerized tomography. Peak torque per liter thigh muscle volume (PT, N X ml-1) was related to crank velocity (CV, rpm) in the following equation: PT = 61.7 - 0.234 CV (r = 0.99). Peak power output was a parabolic function of crank velocity in individual subjects, but maximal power output was achieved at varying crank velocities in different subjects. Fiber type distribution was measured in the two subjects showing the greatest differences and demonstrated that a high proportion of type II fibers may be one factor associated with a high crank velocity for maximal power output. The decline in average power during 30 s of maximal effort was least at 60 rpm (23.7 +/- 4.6% of initial maximal power) and greatest at 140 rpm (58.7 +/- 6.5%). At 60 rpm the decline in power over 30 s was inversely related to maximal oxygen uptake (ml X min-1 X kg-1) (r = 0.69). Total work performed and plasma lactate concentration 3 min after completion of 30-s maximum effort were similar for each crank velocity.

Lower activity of oxidative key enzymes and smaller fiber areas in skeletal muscle of postobese women

1998 ◽  
Vol 275 (3) ◽  
pp. E487-E494 ◽  
Author(s):  
Anne Raben ◽  
Elsebeth Mygind ◽  
Arne Astrup
Keyword(s):  
Skeletal Muscle ◽  
Citrate Synthase ◽  
Fiber Type ◽  
Normal Weight ◽  
Fiber Types ◽  
Fiber Morphology ◽  
Key Enzymes ◽  
Control Subjects ◽  
Type Composition ◽  
And Control

Muscle fiber morphology and activities of four key enzymes, as well as energy metabolism, were determined in nine normal-weight postobese women and nine matched control subjects. No differences in fiber type composition, but a smaller mean fiber area and area of fiber types I and IIb, were found in postobese compared with control subjects ( P < 0.05). The activities of β-hydroxyacyl-CoA dehydrogenase (HADH) and citrate synthase (CS) were 20% lower in postobese than in control subjects ( P < 0.05). However, the activities of lactate dehydrogenase and lipoprotein lipase were not significantly different between postobese and control subjects. Basal metabolic rate and respiratory exchange ratio were also similar, but maximal oxygen uptake (V˙o 2 max) tended to be lower in postobese than in control subjects ( P = 0.06). When adjustments were made for differences inV˙o 2 max, HADH and CS were not different between postobese and control subjects. In conclusion, these data suggest that smaller fiber areas and lower enzyme activities, i.e., markers of aerobic capacity of skeletal muscle, but not fiber composition, may be factors predisposing to obesity.

Early effects of ageing on the mechanical performance of isolated locomotory (EDL) and respiratory (diaphragm) skeletal muscle using the work-loop technique

2014 ◽  
Vol 307 (6) ◽  
pp. R670-R684 ◽  
Author(s):  
Jason Tallis ◽  
Rob S. James ◽  
Alexander G. Little ◽  
Val M. Cox ◽  
Michael J. Duncan ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Power Output ◽  
Muscle Performance ◽  
Maximal Power ◽  
Maximal Power Output ◽  
Age Related ◽  
Loop Technique ◽  
Edl Muscle ◽  
Work Loop

Previous isolated muscle studies examining the effects of ageing on contractility have used isometric protocols, which have been shown to have poor relevance to dynamic muscle performance in vivo. The present study uniquely uses the work-loop technique for a more realistic estimation of in vivo muscle function to examine changes in mammalian skeletal muscle mechanical properties with age. Measurements of maximal isometric stress, activation and relaxation time, maximal power output, and sustained power output during repetitive activation and recovery are compared in locomotory extensor digitorum longus (EDL) and core diaphragm muscle isolated from 3-, 10-, 30-, and 50-wk-old female mice to examine the early onset of ageing. A progressive age-related reduction in maximal isometric stress that was of greater magnitude than the decrease in maximal power output occurred in both muscles. Maximal force and power developed earlier in diaphragm than EDL muscle but demonstrated a greater age-related decline. The present study indicates that ability to sustain skeletal muscle power output through repetitive contraction is age- and muscle-dependent, which may help rationalize previously reported equivocal results from examination of the effect of age on muscular endurance. The age-related decline in EDL muscle performance is prevalent without a significant reduction in muscle mass, and biochemical analysis of key marker enzymes suggests that although there is some evidence of a more oxidative fiber type, this is not the primary contributor to the early age-related reduction in muscle contractility.

Remodeling of skeletal muscle microvasculature in sickle cell trait and α-thalassemia

2010 ◽  
Vol 298 (2) ◽  
pp. H375-H384 ◽  
Author(s):  
Lucile Vincent ◽  
Léonard Féasson ◽  
Samuel Oyono-Enguéllé ◽  
Viviane Banimbek ◽  
Christian Denis ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sickle Cell ◽  
Sickle Cell Trait ◽  
Fiber Type ◽  
A Priori ◽  
Capillary Density ◽  
Work Capacity ◽  
Microvascular Network ◽  
Network Characteristics ◽  
Muscle Tissues

The influence of sickle cell trait and/or α-thalassemia on skeletal muscle microvascular network characteristics was assessed and compared with control subjects [hemoglobin (Hb) AA] in 30 Cameroonian residents [10 HbAA, 5 HbAA α-thalassemia (α-t), 6 HbAS, and 9 HbASα-t] matched for maximal work capacity and daily energy expenditure. Subjects performed an incremental exercise to exhaustion and underwent a muscle biopsy. Muscle fiber type and surface area were not different among groups. However, sickle cell trait (SCT) was associated with lower capillary density ( P < 0.05), lower capillary tortuosity ( P < 0.001), and enlarged microvessels ( P < 0.01). SCT carriers had reduced counts of microvessels <5-μm diameter, but a higher percentage of broader microvessels, i.e., diameter >10 μm ( P < 0.05). α-Thalassemia seemed to be characterized by a higher capillary tortuosity and unchanged capillary density and diameter. Thus, while SCT is a priori clinically benign, we demonstrate for the first time that significant remodeling of the microvasculature occurs in SCT carriers. These modifications may possibly reflect protective adaptations against hemorheological and microcirculatory dysfunction induced by the presence of HbS. The remodeling of the microvascular network occurs to a lesser extent in α-thalassemia. In α-thalassemic subjects, increased capillary tortuosity would promote oxygen supply to muscle tissues and might compensate for the lower Hb content often reported in those subjects.

scholarly journals Skeletal muscle ATP turnover and muscle fiber conduction velocity are elevated at higher muscle temperatures during maximal power output development in humans

2006 ◽  
Vol 290 (2) ◽  
pp. R376-R382 ◽  
Author(s):  
Stuart R. Gray ◽  
Giuseppe De Vito ◽  
Myra A. Nimmo ◽  
Dario Farina ◽  
Richard A. Ferguson
Keyword(s):  
Skeletal Muscle ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Power Output ◽  
Effect Of Temperature ◽  
Muscle Temperature ◽  
Maximal Power ◽  
Maximal Power Output ◽  
Muscle Fiber Conduction Velocity ◽  
Atp Turnover

The effect of temperature on skeletal muscle ATP turnover and muscle fiber conduction velocity (MFCV) was studied during maximal power output development in humans. Eight male subjects performed a 6-s maximal sprint on a mechanically braked cycle ergometer under conditions of normal (N) and elevated muscle temperature (ET). Muscle temperature was passively elevated through the combination of hot water immersion and electric blankets. Anaerobic ATP turnover was calculated from analysis of muscle biopsies obtained before and immediately after exercise. MFCV was measured during exercise using surface electromyography. Preexercise muscle temperature was 34.2°C (SD 0.6) in N and 37.5°C (SD 0.6) in ET. During ET, the rate of ATP turnover for phosphocreatine utilization [temperature coefficient (Q10) = 3.8], glycolysis (Q10 = 1.7), and total anaerobic ATP turnover [Q10 = 2.7; 10.8 (SD 1.9) vs. 14.6 mmol·kg−1 (dry mass)·s−1 (SD 2.3)] were greater than during N ( P < 0.05). MFCV was also greater in ET than in N [3.79 (SD 0.47) to 5.55 m/s (SD 0.72)]. Maximal power output (Q10 = 2.2) and pedal rate (Q10 = 1.6) were greater in ET compared with N ( P < 0.05). The Q10 of maximal and mean power were correlated ( P < 0.05; R = 0.82 and 0.85, respectively) with the percentage of myosin heavy chain type IIA. The greater power output obtained with passive heating was achieved through an elevated rate of anaerobic ATP turnover and MFCV, possibly due to a greater effect of temperature on power production of fibers, with a predominance of myosin heavy chain IIA at the contraction frequencies reached.

Effects of regular physical activity on skeletal muscle structural, energetic, and microvascular properties in carriers of sickle cell trait

2012 ◽  
Vol 113 (4) ◽  
pp. 549-556 ◽  
Author(s):  
Lucile Vincent ◽  
Samuel Oyono-Enguéllé ◽  
Léonard Féasson ◽  
Viviane Banimbek ◽  
Macias Dohbobga ◽  
...  
Keyword(s):  
Physical Activity ◽  
Surface Area ◽  
Sickle Cell ◽  
Citrate Synthase ◽  
Sickle Cell Trait ◽  
Regular Physical Activity ◽  
Time To Exhaustion ◽  
Type I ◽  
Respiratory Chain Complexes ◽  
Oxidative Potential

To assess the effects of regular physical activity on muscle functional characteristics of carriers of sickle cell trait (SCT), 39 untrained (U) and trained (T) hemoglobin (Hb)AA (CON) and SCT subjects (U-CON, n = 12; U-SCT, n = 8; T-CON, n = 10; and T-SCT, n = 9) performed a graded exercise and a time to exhaustion (Tex) test, and were subjected to a muscle biopsy. Maximal power, total work performed during Tex, citrate synthase and cytochrome c oxidase (COX) activities, respiratory chain complexes I and IV content, and capillary density (CD), diameter (COD), and surface area (CSA) were upregulated by the same proportion in T-CON and T-SCT compared with their untrained counterparts. These proportionally similar differences imply that the observed discrepancies between U-SCT and U-CON remained in the trained subjects. Specifically, both CD and COX remained and tended to remain lower, and both COD and CSA remained and tended to remain higher in T-SCT than in T-CON. Besides, carriers of SCT displayed specific adaptations with regular physical activity: creatine kinase activity; complexes II, III, and V content; and type I fiber surface area and capillary tortuosity were lower or unchanged in T-SCT than in U-SCT. In summary, our results show that 1) carriers of SCT adapted almost similarly to CON to regular physical activity for most of the studied muscle characteristics, 2) oxidative potential remains altered in physically active carriers of SCT compared with HbAA counterparts, and 3) the specific remodeling of muscle microvascular network persists in the trained state.

The effects of training in hyperoxia vs. normoxia on skeletal muscle enzyme activities and exercise performance

2007 ◽  
Vol 102 (3) ◽  
pp. 1022-1027 ◽  
Author(s):  
Christopher G. R. Perry ◽  
Jason L. Talanian ◽  
George J. F. Heigenhauser ◽  
Lawrence L. Spriet
Keyword(s):  
Skeletal Muscle ◽  
Exercise Performance ◽  
Power Output ◽  
Citrate Synthase ◽  
Training Stimulus ◽  
Whole Body ◽  
Time To Exhaustion ◽  
Activity Measurements ◽  
Higher Power ◽  
Power Outputs

Inspiring a hyperoxic (H) gas permits subjects to exercise at higher power outputs while training, but there is controversy as to whether this improves skeletal muscle oxidative capacity, maximal O2 consumption (V̇o2 max), and endurance performance to a greater extent than training in normoxia (N). To determine whether the higher power output during H training leads to a greater increase in these parameters, nine recreationally active subjects were randomly assigned in a single-blind fashion to train in H (60% O2) or N for 6 wk (3 sessions/wk of 10 × 4 min at 90% V̇o2 max). Training heart rate (HR) was maintained during the study by increasing power output. After at least 6 wk of detraining, a second 6-wk training protocol was completed with the other breathing condition. V̇o2 max and cycle time to exhaustion at 90% of pretraining V̇o2 max were tested in room air pre- and posttraining. Muscle biopsies were sampled pre- and posttraining for citrate synthase (CS), β-hydroxyacyl-coenzyme A dehydrogenase (β-HAD), and mitochondrial aspartate aminotransferase (m-AsAT) activity measurements. Training power outputs were 8% higher (17 W) in H vs. N. However, both conditions produced similar improvements in V̇o2 max (11–12%); time to exhaustion (∼100%); and CS (H, 30%; N, 32%), β-HAD (H, 23%; N, 21%), and m-AsAT (H, 21%; N, 26%) activities. We conclude that the additional training stimulus provided by training in H was not sufficient to produce greater increases in the aerobic capacity of skeletal muscle and whole body V̇o2 max and exercise performance compared with training in N.

Molecular adaptations in human skeletal muscle to endurance training under simulated hypoxic conditions

2001 ◽  
Vol 91 (1) ◽  
pp. 173-182 ◽  
Author(s):  
M. Vogt ◽  
A. Puntschart ◽  
J. Geiser ◽  
C. Zuleger ◽  
R. Billeter ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Power Output ◽  
High Intensity ◽  
Human Skeletal Muscle ◽  
Fine Tuning ◽  
Maximal Power ◽  
Maximal Power Output ◽  
High Intensity Training ◽  
Hypoxic Conditions ◽  
Intensity Training

This study was performed to explore changes in gene expression as a consequence of exercise training at two levels of intensity under normoxic and normobaric hypoxic conditions (corresponding to an altitude of 3,850 m). Four groups of human subjects trained five times a week for a total of 6 wk on a bicycle ergometer. Muscle biopsies were taken, and performance tests were carried out before and after the training period. Similar increases in maximal O2 uptake (8.3–13.1%) and maximal power output (11.4–20.8%) were found in all groups. RT-PCR revealed elevated mRNA concentrations of the α-subunit of hypoxia-inducible factor 1 (HIF-1) after both high- (+82.4%) and low (+78.4%)-intensity training under hypoxic conditions. The mRNA of HIF-1α736, a splice variant of HIF-1α newly detected in human skeletal muscle, was shown to be changed in a similar pattern as HIF-1α. Increased mRNA contents of myoglobin (+72.2%) and vascular endothelial growth factor (+52.4%) were evoked only after high-intensity training in hypoxia. Augmented mRNA levels of oxidative enzymes, phosphofructokinase, and heat shock protein 70 were found after high-intensity training under both hypoxic and normoxic conditions. Our findings suggest that HIF-1 is specifically involved in the regulation of muscle adaptations after hypoxia training. Fine-tuning of the training response is recognized at the molecular level, and with less sensitivity also at the structural level, but not at global functional responses like maximal O2 uptake or maximal power output.

The KATP channel Kir6.2 subunit content is higher in glycolytic than oxidative skeletal muscle fibers

2011 ◽  
Vol 301 (4) ◽  
pp. R916-R925 ◽  
Author(s):  
Krystyna Banas ◽  
Charlene Clow ◽  
Bernard J. Jasmin ◽  
Jean-Marc Renaud
Keyword(s):  
Skeletal Muscle ◽  
Cross Sections ◽  
Fiber Type ◽  
Energy Levels ◽  
Muscle Fibers ◽  
Metabolic Stress ◽  
Oxidative Capacity ◽  
Fiber Types ◽  
Fiber Damage ◽  
The Individual

It has long been suggested that in skeletal muscle, the ATP-sensitive K+ channel (KATP) channel is important in protecting energy levels and that abolishing its activity causes fiber damage and severely impairs function. The responses to a lack of KATP channel activity vary between muscles and fibers, with the severity of the impairment being the highest in the most glycolytic muscle fibers. Furthermore, glycolytic muscle fibers are also expected to face metabolic stress more often than oxidative ones. The objective of this study was to determine whether the t-tubular KATP channel content differs between muscles and fiber types. KATP channel content was estimated using a semiquantitative immunofluorescence approach by staining cross sections from soleus, extensor digitorum longus (EDL), and flexor digitorum brevis (FDB) muscles with anti-Kir6.2 antibody. Fiber types were determined using serial cross sections stained with specific antimyosin I, IIA, IIB, and IIX antibodies. Changes in Kir6.2 content were compared with changes in CaV1.1 content, as this Ca2+ channel is responsible for triggering Ca2+ release from sarcoplasmic reticulum. The Kir6.2 content was the lowest in the oxidative soleus and the highest in the glycolytic EDL and FDB. At the individual fiber level, the Kir6.2 content within a muscle was in the order of type IIB > IIX > IIA ≥ I. Interestingly, the Kir6.2 content for a given fiber type was significantly different between soleus, EDL, and FDB, and highest in FDB. Correlations of relative fluorescence intensities from the Kir6.2 and CaV1.1 antibodies were significant for all three muscles. However, the variability in content between the three muscles or individual fibers was much greater for Kir6.2 than for CaV1.1. It is suggested that the t-tubular KATP channel content increases as the glycolytic capacity increases and as the oxidative capacity decreases and that the expression of KATP channels may be linked to how often muscles/fibers face metabolic stress.

scholarly journals Aerobic efficiency is associated with the improvement in maximal power output during acute hyperoxia

2017 ◽  
Vol 5 (2) ◽  
pp. e13119 ◽  
Author(s):  
Tom A. Manselin ◽  
Olof Södergård ◽  
Filip J. Larsen ◽  
Peter Lindholm
Keyword(s):  
Power Output ◽  
Maximal Power ◽  
Maximal Power Output
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