Clermont Simard

Histochemical and morphological characteristics of the vastus lateralis muscle in patients with chronic obstructive pulmonary disease.

PURPOSE AND METHODS In this study, we examined the fiber-type proportions, cross-sectional areas (CSA), and capillarization from needle biopsies of the vastus lateralis muscle in 20 patients with chronic obstructive pulmonary disease (COPD) (FEV1 = 37 +/- 11% predicted, peak VO2 = 13 +/- 4 mL.min-1.kg-1) and nine age-matched normal subjects (peak VO2 = 33 +/- 7 mL.min-1.kg-1). The effects of endurance training on these parameters were also evaluated in 11 of the 20 patients with COPD. RESULTS The proportion of Type I fiber was smaller in COPD than normals (34 +/- 14% vs 58 +/- 16 in normals, P < 0.0005) with a corresponding increase in Type IIb fiber (P = 0.015). The CSA of Type I, IIa, and IIab fibers was also smaller in COPD. The capillary to fiber ratio tended to be reduced in patients, but this difference did not reach statistical significance (P = 0.15). The number of capillary contact for Type I, IIa, and IIab fibers was significantly reduced in COPD compared with normal subjects (P < 0.05). When corrected for the CSA, this parameter was similar for both groups. After training, peak VO2 increased by 11% (P < 0.05), the fiber-type proportion remained unchanged, and the CSA of Type I and IIa fibers increased by 31 and 21%, respectively (P < 0.05). Although the number of capillary contact for each fiber types increased with training, the capillary to fiber ratio and the number of capillary contact for the different fiber types relative to their CSA remain unchanged. CONCLUSIONS We conclude that in COPD, 1) the vastus lateralis muscle is characterized by a marked decrease in Type I fiber proportion, an increase in Type IIb fiber proportion, a decrease in Type I, IIa, and IIab fiber CSA and by a relatively preserved capillarization; and 2) a 12-wk training program induces a significant increase in Type I and IIa CSA.

Oxidative enzyme activities of the vastus lateralis muscle and the functional status in patients with COPD

BACKGROUND Enzymatic and histochemical abnormalities of the peripheral muscle may play a role in exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). A study was undertaken to measure the mitochondrial enzyme activity of the vastus lateralis muscle in patients with COPD and to evaluate the relationship between enzyme activities and functional status. METHODS Fifty seven patients with COPD of mean (SD) age 66 (7) years with forced expiratory volume in one second (FEV1) 39 (15)% predicted and peak oxygen uptake (V˙o 2) of 14 (4) ml/min/kg and 15 normal subjects of similar age were included in the study. Each subject performed a stepwise exercise test up to maximal capacity during which five-breath averages of V˙o 2were measured. Muscle specimens were obtained by percutaneous needle biopsy of the vastus lateralis muscle and the activity of two mitochondrial enzymes (citrate synthase (CS) and 3-hydroxyacyl CoA dehydrogenase (HADH)) was measured. The functional status of the patients was classified according to peakV˙o 2. RESULTS CS and HADH activities were markedly reduced in patients with COPD compared with normal subjects (22.3 (2.7) versus 29.5 (7.3) μmol/min/g muscle (p<0.0001) and 5.1 (2.0) versus 6.7 (1.9) μmol/min/g muscle (p<0.005), respectively). The activity of CS decreased progressively with the deterioration in the functional status while that of HADH was not related to functional status. Using a stepwise regression analysis, percentage predicted functional residual capacity (FRC), the activity of CS, oxygen desaturation during exercise, age, and inspiratory capacity (% pred) were found to be significant determinants of peakV˙o 2. The regression model explained 59% of the variance in peak V˙o 2 (p<0.0001). CONCLUSIONS The oxidative capacity of the vastus lateralis muscle is reduced in patients with moderate to severe COPD compared with normal subjects of similar age. In these individuals the activity of CS correlated significantly with peak exercise capacity and independently of lung function impairment.

Chronic Obstructive Pulmonary Disease: Capillarity and Fiber-Type Characteristics of Skeletal Muscle

BACKGROUND The purpose of this investigation was to compare capillarity and fiber type proportions of the vastus lateralis muscle between patients with chronic obstructive pulmonary disease (COPD) and healthy subjects. METHODS Fifteen male subjects were included in the study (8 COPD: 61.0 +/- 1.8 years [mean +/- SEM]; forced expiratory volume in 1 second 42.0 +/- 2.1% predicted; 7 N: age 54.0 +/- 1.1). Subjects were submitted to a symptom-limited maximal exercise test on ergocycle. After a transcutaneous biopsy of the vastus lateralis muscle, sections were cut 8 to 10 microns thick and stained with the Andersen method for capillarity and Stevens method for fiber typing. RESULTS Patients with COPD had a decrease in peak oxygen consumption compared with healthy subjects (1.2 +/- 0.1 versus 3.0 +/- 0.2 L/min). Number of capillaries per square millimeter was lower in patients with COPD versus healthy subjects (92.6 +/- 16.1 and 213.3 +/- 33.5, P < 0.001); percentages of fiber types were 43.5 +/- 5.5% type I, 56.5 +/- 5.5% type II in COPD, and 56.7 +/- 3.4% type I, 43.2 +/- 3.4% type II in healthy subjects (P < 0.05). In addition, capillaries/fiber ratio was 0.83 +/- 0.05 in COPD, and 1.56 +/- 0.10 in healthy subjects (P < 0.001). CONCLUSION As expected, patients with COPD showed a decrease in exercise capacity. The muscle analysis results indicate that patients with COPD have a greater proportion of type II fibers and a much lower capillaries/fiber ratio than normal subjects. We conclude that COPD adversely affects fiber type and capillarization of the lower limbs. This could be partly caused by deconditioning in these patients.

Peripheral muscle endurance and the oxidative profile of the quadriceps in patients with COPD

Background: Based on previously reported changes in muscle metabolism that could increase susceptibility to fatigue, we speculated that patients with chronic obstructive pulmonary disease (COPD) have reduced quadriceps endurance and that this will be correlated with the proportion of type I muscle fibres and with the activity of oxidative enzymes. Methods: The endurance of the quadriceps was evaluated during an isometric contraction in 29 patients with COPD (mean (SE) age 65 (1) years; forced expiratory volume in 1 second 37 (3)% predicted) and 18 healthy subjects of similar age. The electrical activity of the quadriceps was recorded during muscle contraction as an objective index of fatigue. The time at which the isometric contraction at 60% of maximal voluntary capacity could no longer be sustained was used to define time to fatigue (Tf). Needle biopsies of the quadriceps were performed in 16 subjects in both groups to evaluate possible relationships between Tf and markers of muscle oxidative metabolism (type I fibre proportion and citrate synthase activity). Results: Tf was lower in patients with COPD than in controls (42 (3) v 80 (7) seconds; mean difference 38 seconds (95% CI 25 to 50), p<0.001). Subjects in both groups had evidence of electrical muscle fatigue at the end of the endurance test. In both groups significant correlations were found between Tf and the proportion of type I fibres and citrate synthase activity. Conclusion: Isometric endurance of the quadriceps muscle is reduced in patients with COPD and the muscle oxidative profile is significantly correlated with muscle endurance.

Relationship of impairment and functional ability to habitual activity and fitness following spinal cord injury.

Associations between a physically active leisure, physical fitness, impairment and disability have been tested in 123 volunteers (73 with paraplegia and 50 with quadriplegia). Active physical leisure was assessed by the questionnaire of Godin and Shephard (Canadian Journal of Sports Sciences 10, 141-6 1985). Fitness measures included body mass index, peak oxygen intake on a wheelchair ergometer, and tests of muscle strength and endurance (peak isokinetic torque, average muscle power and total muscle work for shoulder flexion, shoulder adduction and elbow flexion at movement speeds of 60 degrees and 180 degrees s-1). Primary impairment was assessed by the ISMGF scale, and secondary impairment was judged from reported pressure scores, spasticity, and urinary infections over the previous 12 months. Scores for self-care and mobility were obtained using a modified Barthel Index. Physically active leisure and fitness were unrelated to secondary impairment. However, functional ability for a given primary impairment was significantly correlated with peak oxygen intake and the three indices of muscle strength, particularly in individuals with high level lesions. Associations between physical activity and functional ability were weaker, but tended in the same direction. Although longitudinal studies are needed to prove the causality of these relationships, the findings point towards a significant influence of fitness status upon functional ability. Rehabilitation teams should thus give a stronger emphasis to systematic exercise conditioning programmes when planning overall treatment following SCI.

Lipofuscin accumulation in the vastus lateralis muscle in patients with chronic obstructive pulmonary disease.

Exercise‐induced oxidative stress has been reported in patients with chronic obstructive pulmonary disease (COPD) and may play a role in muscle fatigue. It is speculated that oxidative stress during exercise originates from the contracting muscles but this has not been documented. The accumulation of lipofuscin, a marker of cellular oxidative damage, was evaluated in the vastus lateralis muscle in 17 patients with COPD and 10 healthy subjects of similar age. Each subject performed a stepwise exercise test up to maximal capacity during which oxygen uptake (& pVO2) was measured. Resting and peak exercise blood gases were also obtained. Two indices of lipofuscin accumulation were used: lipofuscin inclusions/fiber ratio (LI/F) and lipofuscin inclusions/fiber cross‐sectional area ratio (LI/CSA). These ratios were also determined for each specific fiber‐type. LI/F (P < 0.01) and LI/CSA (P < 0.01) were greater in COPD compared to healthy subjects. LI/F and LI/CSA for all fiber types were also greater in COPD (P < 0.001). In both groups, LI/F (P < 0.001) and LI/CSA (P < 0.01) were higher in type I than in type II fibers. LI/F and LI/CSA did not correlate significantly with resting PaO2 and SaO2, peak VO2, and ΔPaO2 and ΔSaO2 during exercise (P > 0.05). Increased lipofuscin accumulation, a marker of oxidative damage, was found in the vastus lateralis muscle in patients with COPD compared to healthy subjects. Oxidative damage of muscle tissue may thus be involved in skeletal muscle dysfunction and wasting in COPD.

Prediction of leisure time exercise behavior among a group of lower‐limb disabled adults

The aim of this study was to predict leisure time exercise behavior among a group of 62 lower-limb disabled adults. The theory of reasoned action proposed by Fishbein (Fishbein & Ajzen, 1975) provided a framework for the study. Variables measured included the Fishbein model variables, habit, education, disability type, fitness level, and a 7-day follow-up of exercise behavior. Some 35% of the variance in exercise behavior could be explained; intention was the strongest predictor (.31, p less than .05). In comparison, the ability to predict intentions to exercise by using the other variables was quite poor, with only 7% of the variance explained by habit. None of the Fishbein model variables contributed to this prediction. These results indicated the importance of specific factors, such as the strength of the exercise habit and the cause of disability, on exercise behavior.

Enzymatic adaptations to suspension hypokinesia in skeletal muscle of young and old rats

Hindlimb hypokinesia was induced in young and old rats. After 3 weeks, the activities of five enzymes have been measured in soleus and medial gastrocnemius muscles. Soleus showed increased activity of hexokinase and decreased activity of phosphofructokinase, lactate dehydrogenase and malate dehydrogenase in both groups. The activity of 3-hydroxyacyl-CoA-dehydrogenase was decreased in the old muscle. Medial gastrocnemius showed decreased activity of phosphofructokinase and lactate dehydrogenase in both groups. The activity of 3-hydroxyacyl-CoA-dehydrogenase was decreased in the old muscle whereas hexokinase increased its activity in the young one. It is concluded that suspension hypokinesia results in changes at the enzymatic level. These changes appear to be related to the age of the muscle and to its fibre composition.

Effects of hypokinesia/hypodynamia on contractile and histochemical properties of young and old rat soleus muscle

To determine if the atrophic process was different in the young and in the aged slow-twitch soleus muscle, in which the aging process is clearly apparent, hind limb hypokinesia/hypodynamia was induced. After 3 weeks, we measured speed-related indices, tension indices, and tension producing capacities. Fiber type composition and fiber cross-sectional area were also investigated. After the treatment, body weight and muscle weight decreased, the most important loss being measured in the young group. The ratio of muscle weight to body weight was not altered by hypokinesia/hypodynamia but this ratio was greater in the 3-month-old control group than in the 22-month-old group. Contraction time and half-relaxation time decreased in both groups. In the control group, the old soleus muscle was slower to contract and relax than in the young muscle. Tension indices and tension producing capacities decreased. These included twitch tension, maximally developed tension, force generated per gram muscle, and specific tension. The mean muscle area and muscle weight of the young soleus decreased more than that of the old soleus. The fiber cross-sectional area was reduced in both groups whereas fiber type composition remained the same after hypokinesia/hypodynamia. The suspension atrophy appeared to be independent of age in the soleus at the contractile level whereas atrophy was greater in the young muscle at the morphometric level.

Effects of Carbohydrate Intake before and during an Ice Hockey Game on Blood and Muscle Energy Substrates

Abstract This study was performed to determine whether carbohydrate (CHO) intake before and during an ice hockey game could spare muscle glycogen and improve performance. The effect of the CHO supplementation on blood glucose, lactate, triglycerides, and glycerol was also investigated. Seven elite collegiate ice hockey players were tested during two regular competitive league matches. The CHO supplement consisted of 100 g of glucose ingested during the 75–210 min period prior to the match and a total of 20 g glucose during the match. A lower blood glucose level before the game and higher glucose concentration after the game were measured in the experimental group. Muscle glycogen content was lowered in both groups. When the glycogen decrease was corrected for the distance skated, a greater sparing of this substrate was observed following the CHO-feeding. These data demonstrate that CHO intake can result in less glycogen usage per distance skated. This finding is of particular relevance for hockey tourname...