[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE Adenosine as an additive in blood cardioplegia is cardioprotective in animal studies, but its clinical role in myocardial protection remains controversial. The aim of this study was to investigate whether the addition of adenosine in continuous cold blood cardioplegia would enhance myocardial protection. METHODS In a prospective double-blind study comparing adenosine 400 μmol l(-1) to placebo in continuous cold blood cardioplegia, 80 patients undergoing isolated aortic valve replacement were randomized into four groups: antegrade cardioplegia with adenosine (n = 19), antegrade cardioplegia with placebo (n = 21), retrograde cardioplegia with adenosine (n = 21) and retrograde cardioplegia with placebo (n = 19). Myocardial arteriovenous differences in oxygen and lactate were measured before, during and after aortic occlusion. Myocardial concentrations of adenine nucleotides and lactate were determined from left ventricular biopsies obtained before aortic occlusion, after bolus cardioplegia, at 60 min of aortic occlusion and at 20 min after aortic occlusion. Plasma creatine kinase (CK-MB) and troponin T were measured at 1, 3, 6, 9, 12 and 24 h after aortic occlusion. Haemodynamic profiles were obtained before surgery and 1, 8 and 24 h after cardiopulmonary bypass. Repeated-measures analysis of variance was used for significance testing. RESULTS Adenosine had no effects on myocardial metabolism of oxygen, lactate and adenine nucleotides, postoperative enzyme release or haemodynamic performance. When compared with the antegrade groups, the retrograde groups showed higher myocardial oxygen uptake (17.3 ± 11.4 versus 2.5 ± 3.6 ml l(-1) at 60 min of aortic occlusion, P < 0.001) and lactate accumulation (43.1 ± 20.7 versus 36.3 ± 23.0 µmol g(-1) at 60 min of aortic occlusion, P = 0.052) in the myocardium during aortic occlusion, and lower postoperative left ventricular stroke work index (27.2 ± 8.4 versus 30.1 ± 7.9 g m m(-2), P = 0.034). CONCLUSIONS Adenosine 400 μmol l(-1) in cold blood cardioplegia showed no cardioprotective effects on the parameters studied. Myocardial ischaemia was more pronounced in patients receiving retrograde cardioplegia.
Interactive Cardiovascular and Thoracic Surgery 11/2011; 14(1):48-55. · 1.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abstract A nephelometric technique has been used to measure concentrations of exogenous triglyceride in arterial and coronary sinus blood. The technique has been validated in a comparison of estimated arterial-coronary sinus differences with those obtained by the chemical determination of total plasma triglyceride. Statistically significant disappearances of exogenous triglyceride across the coronary circulation were observed both during the lipaemia after a fatty meal and during the i.v. infusions of a fat emulsion and glucose solution. The uptake of exogenous triglycerides, about 6% of the arterial concentration, could supply about 50% of the heart's energy requirements. Significant productions of glycerol across the coronary circulation were found in both types of fed state in amounts corresponding to a complete lipolysis of 25–50% of the exogenous triglyceride removed. Net myocardial extractions of free fatty acids were less than in a previous study in the fasting state, which may mean that all triglyceride fatty acid released by lipolysis is not taken up by the myocardium. Also, myocardial extraction of blood glucose was less in the oral fed state than in a previous study in the fasting state.
Journal of Internal Medicine 04/2009; 193(1‐6):233 - 245. · 6.46 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: ABSTRACT – Autonomically mediated cardiovascular responses were evaluated in 15 ALS patients and compared with 15 healthy subjects. The respiratory sinus arrhythmia, the heart rate response to a Valsalva manoeuvre, to isometric handgrip and to a dive reflex test was normal, indicating a normal function of vagal nerves. The heart rate and blood pressure responses during an orthostatic test were normal, indicating a normal function of sympathetic nerves.The increase in blood pressure and blood flow in the contralateral forearm which occurs on handgrip in healthy subjects was reduced in the ALS patients. The cause of this is unclear, but could be related to decreased function of “ergoreceptors” or altered vascular reactivity in atrophic muscle.
[Show abstract][Hide abstract] ABSTRACT: Cardiac output, heart-rate, stroke volume, pressures in the brachial artery, right ventricle and pulmonary artery, forearm blood flow and in addition arterial concentrations of lactate, glucose and free fatty acids were measured in eight healthy male volunteers during i.v. infusion of prostacyclin in doses corresponding to 2 ng, 6 ng and 12 ng min-1 kg-1 b.w. The highest dose almost doubled cardiac output and this was achieved by similar increases in stroke volume and heart-rate. Arterial diastolic and mean pressures decreased slightly while systolic pressure was unaffected. The calculated total systemic vascular resistance decreased to half the initial level. However, forearm blood flow increased insignificantly and forearm vascular resistance was not significantly altered. Pulmonary artery pressure rose only minimally, which in the presence of a great increase in cardiac output indicates pulmonary vasodilatation.Arterial lactate and glucose concentrations were not significantly altered while free fatty acid concentration increased slowly during the infusion period to a similar degree as previously shown in fasting individuals undergoing catheterisation.It is concluded that prostacyclin decreases both pulmonary and total systemic vascular resistance but unlike the most potent vasodilator of the ‘classical’ prostaglandins, PGE17 it has dissimilar vasoactive potency in different systemic vascular beds as evidenced by the insignificant decrease in forearm, simultaneous with the pronounced decrease in total systemic vascular resistance.
[Show abstract][Hide abstract] ABSTRACT: Substrate utilization of the working forearm was studied in nineteen patients with hypertriglyceridaemia (HLP) and compared to nineteen normolipidaemic (NLP) subjects, matched with regard to body weight, body height, intravenous glucose tolerance and age. Arterial-deep venous differences of oxygen, carbon dioxide, free fatty acids (FFA), glucose, lactate and pyruvate was measured. The fractional extraction and oxidation of fatty acids was assessed by intravenous infusion of albumin-bound [3H]palmitate and [14C]oleate. Measurements were made both in the postabsorptive state and after plasma FFA lowering by nicotinic acid.The HLP subjects had, before nicotinic acid, higher arterial concentrations, higher turnover rates of palmitate and oleate and higher plasma glycerol concentrations indicating a greater mobilization of FFA. However, the forearm extraction and oxidation of FFA as well as the calculated total body fatty acid oxidation was similar in HLP and NLP subjects. Nicotinic acid decreased arterial concentrations and turnover rates of FFA to the same extent in HLP and NLP groups, the effect being the same for palmitic and oleic acid. Fractional extraction both of palmitic and of oleic acid increased after nicotinic acid in the NLP but not in the HLP group. Plasma glycerol decrease after nicotinic acid was of the same magnitude in HLP and NLP groups.Thus, (1) an increased uptake of FFA in HLP subjects must occur in other tissues than skeletal muscle and with another fate of the fatty acids than oxidation. The explanation might be an increased incorporation of fatty acids into triglycerides which are subsequently secreted from the liver. (2) The impaired triglyceride removal in skeletal muscle which has been found in HLP subjects is more likely due to an impaired lipolytic activity than to an abnormality in uptake and utilization of hydrolysed fatty acids.No abnormalities in carbohydrate metabolism were found in these HLP subjects with normal glucose tolerance.
European Journal of Clinical Investigation 03/2008; 7(6):549 - 556. · 3.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To study interstitial IGF-I concentrations in resting and exercising skeletal muscle in relation to the circulating components of the IGF-IGF binding protein (IGFBP) system.
Seven women performed endurance exercise with 1 leg (Ex-leg) for 1 h. The resting leg (Rest-leg) served as a control. IGF-I was determined in microdialysate (MD) and was compared with veno-arterial (v-a) concentrations of circulating IGF-IGFBP components.
Median (range) basal MD-IGF-I was 0.87 (0.4-1.5) microg/l or 0.4 (0.2)% of total-IGF-I (t-IGF-I) determined in arterial serum and in the same concentration range as free dissociable IGF-I (f-IGF-I). Rest-leg MD-IGF-I decreased, reaching significance after exercise. Ex-leg MD-IGF-I was unchanged during exercise and declined after exercise at the level of significance (P = 0.05). There was a release of f-IGF-I from the Ex-leg into the circulation at the end of and shortly after exercise. A small but significant increase in circulating IGFBP-1 was detected at the end of exercise and IGFBP-1 increased further after exercise. Although interleukin-6 (IL-6) has been associated with IGFBP-3 proteolysis, the circulating molecular forms of IGFBP-3 remained unchanged in spite of an IL-6 release from the muscle compartment.
Circulating IGFBP-1 is related to interstitial IGF-I in resting muscle although the temporal relationship may not be simple. Further studies should explore the role of local release of IGF-I and its impact on IGF-I activity during contraction.
European Journal of Endocrinology 11/2007; 157(4):427-35. · 3.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We tested the hypothesis that the work of the heart was not a limiting factor in the attainment of maximal oxygen uptake (VO2 max). We measured cardiac output (Q) and blood pressures (BP) during exercise at two different rates of maximal work to estimate the work of the heart through calculation of the rate-pressure product, as a part of the ongoing discussion regarding factors limiting VO2 max. Eight well-trained men (age 24.4 +/- 2.8 yr, weight 81.3 +/- 7.8 kg, and VO2 max 59.1 +/- 2.0 ml x min(-1) x kg(-1)) performed two maximal combined arm and leg exercises, differing 10% in watts, with average duration of time to exhaustion of 4 min 50 s and 3 min 40 s, respectively. There were no differences between work rates in measured VO2 max, maximal Q, and peak heart rate between work rates (0.02 l/min, 0.3 l/min, and 0.8 beats/min, respectively), but the systolic, diastolic, and calculated mean BP were significantly higher (19, 5, and 10 mmHg, respectively) in the higher than in the lower maximal work rate. The products of heart rate times systolic or mean BP and Q times systolic or mean BP were significantly higher (3,715, 1,780, 569, and 1,780, respectively) during the higher than the lower work rate. Differences in these four products indicate a higher mechanical work of the heart on higher than lower maximal work rate. Therefore, this study does not support the theory, which states that the work of the heart, and consequently VO2 max, during maximal exercise is hindered by a command from the central nervous system aiming at protecting the heart from being ischemic.
Journal of Applied Physiology 03/2007; 102(2):781-6. · 3.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Nine healthy men trained one leg under normobaric (N) conditions (N-leg), the other leg under hypobaric (H; 572 mmHg) conditions (H-leg) each one 30 min, 3–4 times per week for 4 weeks at 65% of the one-legged maximal work load that could be performed for 2 min (Wmax). They performed one-legged exercise tests to fatigue before and after the training period under N conditions at a load corresponding to 80% of one-legged Wmax. Muscle biopsies were taken before training from one leg and after training both from the N-leg and the H-leg at rest and after 15-min exercise and analysed for high-energy phosphates and glycogen and their degradation products. Training under N as well as under H conditions improved local energy balance in the leg (less lactate and inosine monophosphate accumulation). However, a discrepancy was found between the previously demonstrated greater increase in local oxidative potential in the H-leg than in the N-leg and the local energy balance during submaximal exercise, which improved less in the H-leg than in the N-leg (lower energy charge and higher adenosine monophosphate content). Despite less improved local energy balance after 15 min of exercise, the time to fatigue was somewhat longer in the H-leg.
Scandinavian Journal of Medicine and Science in Sports 01/2007; 2(1):2 - 6. · 3.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The effect of short-term altitude training on sea-level physiological characteristics in elite runners was investigated. Seven middle-distance runners (6 men, 1 woman) belonging to the Swedish national team (mean age 23 years) spent 2 weeks of training at 2000 m above sea level in Kenya. Treadmill tests were performed before and 6 and 12 d after the altitude sojourn. Six other runners (4 men, 2 women) had a corresponding training sojourn at sea level in Portugal (control group). Ro of the runners (1 man, 1 woman) in the Kenya group were omitted from the study because of gastroenteritis. The maximal oxygen uptake (VO2 max; pretravel: Kenya group 212 and control group 188 ml · kg−0.75 - min−1), maximal treadmill time and oxygen cost of running were unchanged in both groups. The maximal oxygen deficit increased in all subjects after the Kenya sojourn (mean 19±6%). Heart rates during running at specified submaximal running velocities were lower post-altitude (Kenya group), but tended to be higher after sea-level training (control group). Maximal heart rate was unchanged in both groups. Perceived exertion (Borg) during submaximal running was lower post-altitude. Submaximal and maximal blood lactate and plasma catecholamine concentrations were not altered in any of the groups. Post-exhaustive plasma ammonia levels were decreased 12 d after altitude descent in the Kenya group. The results suggest an unchanged aerobic capacity in elite middle-distance runners after short-term training at moderate altitude. However, a change in the circulatory regulation during submaximal exercise was observed. Furthermore, anaerobic capacity improved but this bore no clear relation to lactate or ammonia metabolism.
Scandinavian Journal of Medicine and Science in Sports 01/2007; 1(4):205 - 214. · 3.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study evaluates a possible contribution of adipose tissue to the elimination of plasma ammonia (NH(3)) after high-intensity sprint exercise. In 14 healthy men and women, repeated blood samples for plasma NH(3) analyses were obtained from brachial artery and from a subcutaneous abdominal vein before and after three repeated 30-s cycle sprints separated by 20 min of recovery. Biopsies from subcutaneous abdominal adipose tissue were obtained and analyzed for glutamine and glutamate content. After exercise, both arterial and abdominal venous plasma NH(3) concentrations were lower in women than in men (P < 0.01 and P < 0.001, respectively). All postexercise measurements showed sex-independent positive arterio-subcutaneous abdominal venous plasma NH(3) concentration differences (a-v(abd)), indicating a net uptake of NH(3) from blood to adipose tissue. However, the fractional extraction (a-v(abd)/a) of NH(3) was higher in women than in men (P < 0.05). The glutamine-to-glutamate ratio in adipose tissue was increased after the second and third bout of sprint exercise (2.2 +/- 0.7 and 1.6 +/- 0.8, respectively) compared with the value at rest (1.2 +/- 0.6), suggesting a reaction of the extracted NH(3) with glutamate resulting in its conversion to glutamine. Adipose tissue may thus play an important physiological role in eliminating plasma NH(3) and thereby reducing the risk of NH(3) intoxication after high-intensity exercise.
Journal of Applied Physiology 01/2007; 101(6):1576-80. · 3.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Muscle metabolism during one-legged submaximal exercise executed in a hypobaric chamber (corresponding to 2300 m above sea level) was studied by percutaneous muscle biopsies from the vastus lateralis and compared with corresponding data from the other leg, exercising at the same absolute load under normobaric conditions on another Occasion. After 15 min of exercise, the adenosine triphosphate/adenosine diphosphate ratio was lower and inosine 5-monophosphate higher in the hypobaric than in the normobaric leg. The possibility is suggested that this metabolic alteration stimulates increased expression of oxidation-related mitochondrial enzymes. Despite this sign of energy depletion, there was no indication of increased glycolysis. A tendency to increased citrate concentration in the hypobaric leg could suggest an increased mobilization and utilization of fat, which auld have counteracted any stimulating effect on the glycolytic rate.
Scandinavian Journal of Medicine and Science in Sports 01/2007; 2(1):7-9. · 3.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Deep water running with wet vest is a safe form of exercise for elderly with mobility limitations. However, it is not known to what extent their aerobic power may be improved. Therefore, the aim was to assess the effects of high intensity deep water interval training with vest in elderly women. Twenty-nine healthy women 69 +/- 4 years old participated. They performed a graded maximal exercise test on the cycle ergometer. They were randomly assigned to a control or to a training group. A submaximal exercise test on the cycle ergometer was executed only by the training group. They trained in deep water running/walking wearing a vest two times a week for 8 weeks. The target heart rate was 75% of maximal heart rate and the training consisted of several short working periods and resting intervals. After the intervention the heart rate at rest was 8% lower for the training group (P<0.01). Their heart rate at submaximal exercise was 3% less (P<0.01), their maximal oxygen uptake was raised by 10% (P<0.01), and their maximal ventilation was increased 14% (P<0.01). The values for the control group were unaltered after the period of intervention. In conclusion, high intensity deep water running with vest improves submaximal work capacity, maximal aerobic power, and maximal ventilation with the effects transferable to land-based activities in elderly women.
[Show abstract][Hide abstract] ABSTRACT: In the present article, three scales developed by Borg are compared on bicycle ergometer work. In the first study, comparing the Borg Ratings of Perceived Exertion (RPE) and Category scales with Ratio properties (CR10) scales, 40 healthy subjects (12 men and eight women for each scale) with a mean age of about 30 years (SD approximately 6) participated. A work-test protocol with step-wise increase of work loads every minute was used (20 W increase for men and 15 W for women). Ratings and heart rates (HRs) were recorded every minute and blood lactates every third minute. Data obtained with the RPE scale were described with linear regressions, with individual correlations of about 0.98. Data obtained with the CR10 scale could also be described by linear regressions, but when described by power functions gave exponents of about 1.2 (SD approximately 0.4) (with one additional constant included in the power function). This was significantly lower than the exponent of between 1.5 and 1.9 that has previously been observed. Mean individual correlations were 0.98. Blood lactate concentration grew with monotonously increasing functions that could be described by power functions with a mean exponent of about 2.6 (SD approximately 0.6) (with two additional constants included in the power functions). In the second study, where also the more recently developed Borg CR100 scale (centiMax) was included, 24 healthy subjects (12 men and 12 women) with a mean age of about 29 years (SD approximately 3) participated in a work test with a step-wise increase of work loads (25 W) every third minute. Ratings and HRs were recorded. RPE values were described by linear regressions with individual correlations of about 0.97. Data from the two CR scales were described by power functions with mean exponents of about 1.4 (SD approximately 0.5) (with a-values in the power functions). Mean individual correlations were about 0.98. In both studies, a tendency for a deviation from linearity between RPE values and HRs was observed. The obtained deviations from what has previously been obtained for work of longer duration (4-6 min) points to a need for standardization of work-test protocols and to the advantage of using CR scales.
Scandinavian Journal of Medicine and Science in Sports 03/2006; 16(1):57-69. · 3.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of the study was to examine submaximal and maximal physiological responses and perceived exertion during deep-water running with a vest compared with the responses during treadmill running in healthy elderly women. Eleven healthy women 70 +/- 2 years old participated. On two different occasions they performed a graded maximal exercise test on a treadmill on land and a graded maximal exercise test in water wearing a vest. At maximal work the oxygen uptake was 29% lower (p < .05), the heart rate was 8% lower (p < .05), and the ventilation was 16% lower (p < .05) during deep-water running than during treadmill running. During submaximal absolute work the heart rate was higher during deep-water running than during treadmill running for the elderly women. The participants had lower maximal oxygen uptake, heart rate, ventilation, respiratory-exchange ratio, and rate of perceived exertion during maximal deep-water running with a vest than during maximal treadmill running. These responses were, however, higher during submaximal deep-water running than during treadmill running.
Journal of aging and physical activity 02/2006; 14(1):29-40. · 1.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Method: A metabolic analysis of hypothermic retrograde continuous blood cardioplegia with antegrade warm cardioplegic induction was performed in a prospective study of 15 patients scheduled for elective coronary artery bypass grafting. Arterial and coronary sinus blood samples were simultaneously taken: before establishing cardiopulmonary bypass, after anterograde warm cardioplegic induction, when the aortic clamp was removed and 10, 30 and 60 minutes after reperfusion to analyze the oxygen content and lactate concentration. Four transmural left ventricular biopsy samples were obtained: before aortic clamping, immediately after the initial cardioplegia bolus, immediately before aortic declamping and 30 minutes after reperfusion to analyze the levels of ATP, ADP, AMP and lactate in the myocardium. The CK-MB isoenzyme was analysed in venous blood samples. Results: There were no mortalities in the group. Inotropic support was not necessary in any patients and no peri- or postoperative myocardial infarction was detected. There was a decrease in the arterial-venous extraction of oxygen and lactate in the heart during reperfusion, a partial recovery occurred at 60 minutes of reperfusion. The levels of ATP and the other nucleotides in the myocardium were maintained during aortic clamping, but these levels decreased during the first 30 minutes of reperfusion. The lactate accumulated in the heart muscle during aortic clamping with a decrease occurring during reperfusion. Conclusions: From a metabolic point of view the method could not avoid an anaerobic metabolism during cross- clamping and only after 60 minutes of reperfusion there was a satisfactory metabolic recovery. These alterations are probably a reflection of cellular ischemic injury that occurs during cross-clamping and they seem to be of transitory effect. A better myocardium protection was observed with the addiction of anterograde warm induction cardioplegia. Descriptors: Cardioplegic solutions. Cardiac arrest,
Brazilian Journal of Cardiovascular Surgery 01/2005; 20(4).
[Show abstract][Hide abstract] ABSTRACT: The aim was to quantify the time spent at different exercise intensities for male golfers, in relation to age, while walking a "normal" 18-hole golf course.
19 healthy male golfers (six 27 (5) years old, seven of 50 (7) and six of 75 (4) years) performed a maximal exercise test on a treadmill (maximal oxygen uptake and maximal heart rate were measured). Within one week, they played an "average" 18-hole course starting at 7:00 a.m. During the round, their heart rate was monitored with a Polar Vantage heart rate monitor, which sampled the heart rate every 5 seconds. Body weight was measured before and after the round. Blood glucose was taken at rest before the round and after each 3rd hole. Perceived exertion and perceived pain in muscles and joints were rated using the CR 10 Borg scale just before reaching each green and after a few selected uphill parts of the course.
High intensity of exercise was reached during 6% of the total playing time for the young, 30% for the middle-aged and 70% for the elderly golfers, playing 18 holes (p < 0.05). The golfers' heart rate was below 50% of their individual maximal heart rate, 18% of total time for young golfers, 16% for the middle-aged, and not at all for the elderly. Perceived exertion, breathlessness and leg fatigue were rated in a similar manner for all three groups. Perceived pain in joints and muscles was rated extremely weak except in a few players who had some known joint or muscle problem. The mean blood glucose level fell by 20% for the young (p < 0.05), 10% for the middle-aged, and 30% for the elderly players (p < 0.05) after 18 holes of play. Body weight was reduced 0.7% similarly for all three groups (p < 0.05).
Walking an 18-hole golf course corresponds to an exercise intensity which is moderate and high for the elderly, mainly low to moderate for the middle-aged, and low for young male golfers. All golfers, regardless of age, perceived their exertion similarly as weak to moderate.
Aging clinical and experimental research 10/2004; 16(5):375-81. · 1.01 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The effects of short-term exercise training on vascular endothelial growth factor (VEGF) and one of its regulatory transcription factors, the hypoxia inducible factor 1 (HIF-1) subunit, were studied in eight healthy males. Muscle and blood samples were obtained before the 1st, and 24 h after the 7th training session. VEGF and HIF-1 mRNA were analysed using RT-PCR, VEGF mRNA localization with in situ hybridization and VEGF protein with ELISA. Concurrent increases in VEGF mRNA and protein levels were observed in skeletal muscle, and the mRNA was expressed within the skeletal muscle fibres and in cells in the interstitium. These data support the idea of a pretranslational regulation of exercise-induced changes in VEGF mRNA, and indicate that increased VEGF protein expression is an early event in skeletal muscle adaptation to training. Furthermore, different cell types may act as sources for the production of angiogenic factors in response to exercise. The levels of HIF-1 mRNA subunits did not change, suggesting no change in HIF-1 mRNA transcript levels in the regulation of training-induced VEGF expression. In contrast to increased tissue VEGF expression, the arterial and femoral venous plasma levels of VEGF were decreased by training, which may indicate an exercise-induced enhancement of the peripheral uptake of VEGF.
Pflügers Archiv - European Journal of Physiology 10/2002; 444(6):752-9. · 4.87 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study was performed to investigate if glycogen loading of skeletal muscles, by binding water, would effect the cross-sectional area (CSA) and if an altered water content would alter the transverse relaxation time (T2) measured by magnetic resonance imaging (MRI). Five healthy volunteers participated in a programme with 4 days of extremely carbohydrate-restricted meals followed by 4 days of extremely high carbohydrate intake. The CSA and T2 of thigh and calf muscles were related to the intramuscular glycogen content evaluated at days 4 and 8. An increase in glycogen content from 281 to 634 mmol kg(-1) dry wt increased the CSA of the vastus muscles by 3.5% from 78 +/- 11 to 80 +/- 12 cm2 and the thigh circumference by 2.5% from 146 +/- 20 to 150 23 cm2. Calf circumference increased non-significantly by 4% from 78 +/- 15 to 82 +/- 19 cm2. Mono-exponential T2 decreased in m. tibialis anterior from 27.8 +/- 1.2 to 26.9 +/- 1.7 ms, did not change in m. vastus lateralis 26.5 +/- 1.9 ms/26.6 +/- 1.3 ms or in m. gastrocnemius 29.5 +/- 1.0 ms/29.8 +/- 1.9 ms. Glycogen loading increased the signal intensity mainly at different echo times (TE) 15 and 30 ms. The study shows that increased glycogen filling in the muscles increases muscle CSA and that this can be detected by MRI. The signal intensity increased the most at shorter TEs suggesting a more tight intracellular binding of water in glycogen loaded muscles.