Quantifying the effect of hand preference on upper limb bone mineral and soft tissue composition in young and elderly women by dual-energy X-ray absorptiometry

Summary. The purpose of this study was to quantify the effect that hand preference has on upper limb bone mineral and soft tissue composition in healthy young and elderly women. Bone mineral content (BMC) in grams, bone mineral density (BMD) in g cm^-2, fat-free soft tissue (FFST) in grams, fat tissue (g), and percent fat were determined by dual-energy X-ray absorptiometry (DXA) for dominant and non-dominant upper limbs as well as total body fat (%) in 25 young (26–6 ± 4–3 years, mean ± SD) and 35 elderly women (68–4 ± 2–9 years). For both groups, the dominant upper limb had a greater BMC (P<0–001), BMD (young, P<0001; elderly, P<0–05), and FFST mass (P<0–001), and a lower percent fat (young, P<0–01; elderly, P<0–05) than the non-dominant limb; however, there was no difference between limbs for total fat mass. BMC, BMD, and FFST in the dominant limb of young women were 7–1%, 1–8%, and 5–1% greater than the non-dominant limb, while for older women the differences were 5–3%, 10%, and 4–2%. Relative fat of the dominant limb was 3–0% and 1 -3% less than the non-dominant limb for young and older women, respectively. Age did not affect the percent bone mineral or soft tissue difference. A higher bone mineral and FFST mass in the dominant limb is expected due to the greater activity demands placed upon these tissues. However, a larger bone and FFST mass increases the total mass of the dominant limb, resulting in a dilution of the fat tissue mass and hence a reduced fat percent for the limb. This study indicates that hand preference affects the tissue composition of the upper limb in both young and elderly women, resulting in an increased bone mineral and FFST mass with no change in absolute fat mass. Hand preference should be taken into account when upper limb bone mineral and/or soft tissue composition is assessed.     

Autonomic nervous function at rest in aerobically trained and untrained oldermen

Therelationship between aerobictraining, vagal influence on the heart and ageing was examined by assessing aerobic fitness andresting heart rate variability in trained and untrained older men. Subjects were 11 trained cyclistsand runners (mean age=6±61·6 years) and 11 untrained, age-matchedmen (mean age=66±1·2 years). Heart rate variability testing involvedsubjects lying supine for 25 min during which subjects’ breathing was paced andmonitored (7·5 breaths min^?1). Heart rate variability was assessedthrough time series analysis (HRV_ts) of the interbeat interval. Results indicated thattrained older men (3·55±0·21 l min^?1) hadsignificantly (P<0·05) greater VO _2maxthan that of control subjects (2·35±0·15 l min^?1).Also, trained older men (52±1·8 beats min^?1) hadsignificantly (P<0·05) lower supine resting heart rate than that of controlsubjects (65±4·2 beats min^?1). HRV_ts at highfrequencies was greater for trained men (5·98±0·22) than for untrainedmen (5·23±0·32). These data suggest that regular aerobic exercise inolder men is associated with greater levels of HRV_ts at rest.     

Muscular adaptations to fatiguing exercise with and without blood flow restriction

The purpose of this study was to determine the muscular adaptations to low‐load resistance training performed to fatigue with and without blood flow restriction (BFR). Middle‐aged (42–62 years) men (n = 12) and women (n = 6) completed 18 sessions of unilateral knee extensor resistance training to volitional fatigue over 6 weeks. One limb trained under BFR, and the contralateral limb trained without BFR [free flow (FF)]. Before and after the training, measures of anterior and lateral quadriceps muscle thickness (MTh), strength, power and endurance were assessed on each limb. The total exercise training volume was significantly greater for the FF limb compared with the BFR limb (P<0·001). Anterior quadriceps thickness and muscle function increased following the training in each limb with no differences between limbs. Lateral quadriceps MTh increased significantly more (P<0·05) in the limb trained under BFR (BFR: 3·50 ± 0·61 to 3·67 ± 0·62 cm; FF: 3·49 ± 0·73 to 3·56 ± 0·70 cm). Low‐load resistance training to volitional fatigue both with and without BFR is viable options for improving muscle function in middle‐aged individuals. However, BFR enhanced the hypertrophic effect of low‐load training and reduced the volume of exercise needed to elicit increases in muscle function.     

Plasma lipid and lipoprotein profiles in pre- and post-menopausal middle-aged runners

Summary. Plasma lipid and lipoprotein profiles were compared in middle-aged trained and untrained women before and after menopause. Subjects were assigned to one of four groups: (1) pre-menopausal trained (Pre-T: n= 17, aged 42 ±5 years, body fat 19±5%, training distance 53 ±20 km week^-1, V?o_2max 49 ±4 ml kg^-1 min^-1, mean±SD); (2) pre-menopausal untrained (Pre-UT: n= 26, 42 ±5 years, 24 ±7%, 34 ±6 ml kg^-1 min^-1); (3) post-menopausal trained (Post-T: n= 16, 54 ±3 years, 20 ±4%, 43 ±19 km week^-1, 41 ±5 ml kg^-1 min^-1); and (4) post-menopausal untrained (Post-UT: n= 15, 55 ±3 years, 25 ±6%, 31 ±3 ml kg^-1 min^-1). There were no significant differences in total cholesterol (range 173–194 mg dl^-1), triglyceride (56–72 mg dl^-1), and HDL-cholesterol (HDLC: 76–85 mg dl^-1) among the four groups. LDL-cholesterol (LDLC) in the post-menopausal women (Post-T: 96 ±32 mg dl^-1; Post-UT: 104 ±23 mg dl^-1) tended to be higher than in the premenopausal women (Pre-T: 86 ± 25 mg dl^-1, Pre-UT: 81 ± 23 mg dl^-1). LDLC/HDLC ratio in Post-UT (1·42 ±0·38 unit) was higher than in the pre-menopausal women (Pre-T: 1·03±0·31 unit, P<0·01; Pre-UT: 1·10±0·38 unit, P<0·05), whereas the ratio in Post-T (1·20 ±0·38 unit) was not different from those of the pre-menopausal groups. These results suggest that endurance running protects against the increase in LDLC/HDLC ratio that frequently occurs after menopause.     

Effects of intense exercise training on endothelium-dependent exercise-induced vasodilatation

To determine whether intense exercise training affects exercise-induced vasodilatation, six subjects underwent 4 weeks of handgrip training at 70% of maximal voluntary contraction. Exercise forearm vascular conductance (FVC) responses to an endothelium-dependent vasodilator (acetylcholine, ACH; 15, 30, 60 μg min^?1) and an endothelium-independent vasodilator (sodium nitroprusside, SNP; 1·6, 3·2, 6·4 μg min^?1) and FVC after 10 min of forearm ischaemia were determined before and after training. Training elicited significant (P<0·001) increases in grip strength (43·4 ± 2·3 vs. 64·1 ± 3·5 kg, before vs. after, mean ± SEM), forearm circumference (26·7 ± 0·4 vs. 27·9 ± 0·4 cm) and maximal FVC (0·4630 ± 0·0387 vs. 0.6258 ± 0·0389 units, P<0·05). Resting FVC did not change significantly with training (0·0723 ± 0·0162 vs. 0.0985 ± 0·0171 units, P>0·4), but exercise FVC increased (0·1330 ± 0·0190 vs. 0.2534 ± 0·0387 units, P<0·05). Before and after the training, ACH increased exercise FVC above the control (no drug) exercise FVC, whereas SNP did not. Training increased (P<0·05) the exercise FVC responses to ACH (0·3344 ± 0·1208 vs. 0.4303 ± 0·0858 units, before vs. after training, 60 μg min^?1) and SNP (0·2066 ± 0·0849 vs. 0.3172 ± 0·0628 units, 6·4 μg min^?1). However, these increases were due to the increase in control (no drug) exercise FVC, as the drug-associated increase in exercise FVC above control did not differ between trials (P>0·6). These results suggest that exercise FVC is increased by both exercise training and stimulating the release of endothelium-dependent vasodilators. However, training does not affect the vascular response to these vasodilators.     

Effect of regular physical training on age-associated alteration of body composition in men

Body composition changes with increasing age in men, in that lean body mass decreases whereas fat mass increases. Whether this altered body composition is related to decreasing physical activity or to the known age-associated decrease in growth hormone secretion is uncertain. To address this question, three groups of healthy men (n = 14 in each group), matched for weight, height and body mass index, were investigated using dual-energy X-ray absorptiometry, indirect calorimetry and estimate of daily growth hormone secretion [i.e. plasma insulin-like growth factor I (IGF-I) levels]. Group 1 comprised young untrained subjects aged 31.0 ± 2.1 years (mean ± SEM) taking no regular physical exercise; group 2 consisted of old untrained men aged 68.6 ± 1.2 years; and group 3 consisted of healthy old men aged 67.4 ± 1.2 years undergoing regular physical training for more than 10 years with a training distance of at least 30 km per week. Subjects in group 3 had for the past three years taken part in the ‘Grand Prix of Berne’, a 16.5-km race run at a speed of 4.7 ± 0.6 min km^?1 (most recent race). Fat mass was more than 4 kg higher in old untrained men (P < 0.01, anova ) than in the other groups (young untrained men, 12.0 ± 0.9 kg; old untrained men, 16.1 ± 1.0 kg; old trained men, 11.0 ± 0.8 kg), whereas body fat distribution (i.e. the ratio of upper to lower body fat mass) was similar between the three groups. The lean mass of old untrained men was more than 3.5 kg lower (P < 0.02, anova ) than in the other two groups (young untrained men, 56.4 ± 1.0 kg; old untrained men, 52.4 ± 1.0 kg; old trained men, 56.0 ± 1.0 kg), mostly because of a loss of skeletal muscle mass in the arms and legs (young untrained men, 24.0 ± 0.5 kg; old untrained men 20.8 ± 0.5 kg; old trained men, 23.6 ± 0.7 kg; P < 0.01, anova ). Resting metabolic rate per kilogram lean mass decreased with increasing age independently of physical activity (r = ?0.42, P < 0.005). Fuel metabolism was determined by indirect calorimetry at rest. Protein oxidation was similar in the three groups. Old untrained men had higher (P < 0.001) carbohydrate oxidation (young untrained men, 13.2 ± 1.0 kcal kg^?1 lean mass; old untrained men, 15.2 ± 1.3 kcal kg^?1; old trained men, 7.8 ± 0.8 kcal kg^?1), but lower (P < 0.05, anova ) fat oxidation (young untrained men, 10.1 ± 1.2 kcal kg^?1 lean mass; old untrained men, 6.5 ± 1.0 kcal kg^?1; old trained men, 13.7 ± 1.0 kcal kg^?1) than the other two groups. Mean plasma IGF-I level in old trained men was higher than in old untrained men (P < 0.05), but was still lower than that observed in young untrained men (P < 0.005) (young untrained men, 236 ± 24 ng mL^?1; old untrained men, 119 ± 13 ng mL^?1; old trained men, 166 ±14 ng mL^?1). In summary, regular physical training in older men seems to prevent the changes in body composition and fuel metabolism normally associated with ageing. Whether regular physical training in formerly untrained old subjects would result in similar changes awaits further study.     

Altered skeletal muscle glucose transport and blood lipid levels in habitual cigarette smokers

We determined whether habitual cigarette smoking alters insulin-stimulated glucose transport and GLUT4 protein expression in skeletal muscle. Vastus lateralis muscle was obtained from 10 habitual cigarette smokers and 10 control subjects using an open muscle biopsy procedure. Basal 3-O-methylglucose transport was twofold higher (P > 0·01) in muscle from habitual smokers (0·05 ± 0·08 vs. 1·04 ± 0·19 μmol ml^?1 h^?1; controls vs. smokers respectively). Insulin (600 pmol l^?1) increased glucose transport 2·6-fold (P > 0·05) in muscle from control subjects, whereas no significant increase was noted in habitual smokers. Skeletal muscle GLUT4 protein expression was similar between the groups. FFA levels were elevated in the smokers (264 ± 49 vs. 748 ± 138 μmol l^?1 for control subjects vs. smokers; P < 0·05), and serum triglyceride levels were increased in the smokers (0·9 ± 0·2 vs. 2·3 ± 0·6 mmol l^?1 for control subjects vs. smokers; P < 0·05). Skeletal muscle carnitine palmitil (acyl) transferase activity was similar between the groups, indicating that FFA transport into the mitochondria was unaltered by cigarette smoking. In conclusion, cigarette smoking appears to have a profound effect on glucose transport in skeletal muscle. Basal glucose transport is markedly elevated, whereas insulin-stimulated glucose transport is impaired. These changes cannot be explained by altered protein expression of GLUT4, but may be related to increased serum FFA and triglyceride levels. These findings highlight the importance of identifying habitual cigarette smokers in studies aimed at assessing factors that lead to alterations in lipid and glucose homeostasis in people with non-insulin-dependent diabetes mellitus (NIDDM).     

Unilateral static and dynamic hamstrings stretching increases contralateral hip flexion range of motion

Static (SS) and dynamic stretching (DS) can lead to subsequent performance impairments or enhancement with the stretched limb. Crossover or non-local muscle fatigue (NLMF) refers to unilateral fatigue-induced impairments in a contralateral or non-exercised muscle. Whereas there are conflicting findings in the NLMF literature, there are few studies examining the effect of an acute bout of SS or DS on contralateral flexibility, torque or power. Fourteen highly trained subjects (means ± standard deviations: 18 ± 2 years; 179·4 ± 4·6 cm; 70·5 ± 6·3 kg; %body fat: 10·7 ± 2·5%) were tested before and following separate sessions of eight repetitions of 30 s of unilateral hip flexion SS or DS. Pre- and postintervention testing at 1 and 10 min included hip flexor range of motion (ROM), isokinetic leg flexion torque and power at 60°.s⁻¹ and 300°.s⁻¹ of the stretched and contralateral limbs. The stretched limb had a 6·3% (P = 0·01; ES: 0·91) ROM increase with DS at 10 min. The contralateral non-stretched hip flexors experienced ROM increases with SS of 5·7% (P = 0·02; ES: 0·68) from pretest to 1 min post-test, whereas DS showed 7·1% (P<0·0001; ES: 1·09) and 8·4% (P = 0·005; ES: 0·89) increases, respectively. There were no relative differences in ROM changes between conditions or limbs nor any stretch-induced changes in isokinetic torque or power. In conclusion, unilateral SS and DS augment contralateral limb ROM likely through an increased stretch tolerance.     

Morpho‐functional response of the elbow extensor muscles to twelve‐week self‐perceived maximal resistance training

The aim of this study was to determine morphological and functional changes of the elbow extensor muscles in response to a 12‐week self‐perceived maximal resistance training (MRT). Twenty‐one healthy sedentary young men were engaged in elbow extensor training using isoacceleration dynamometry for 12 weeks with a frequency of five sessions per week (five sets of ten maximal voluntarily contractions, 1‐min rest period between each set). Prior to, at 6 weeks and after the training, a series of cross‐sectional magnetic resonance images of the upper arm were obtained and muscle volumes were calculated. Maximal and endurance strength increased (P<0·01) by 15% and 45% at 6 weeks, and by 29% and 70% after 12 weeks compared with baseline values, while fatigue rate of the elbow extensors decreased by 67%. The volume of triceps brachii increased in both arms (P<0·01) by 4% at 6 weeks, and by 8% after 12 weeks compared with baseline values (right arm – from 487·4 ± 72·8 cm³ to 505·8 ± 72·3 cm³ after 6 weeks and 525·3 ± 73·7 cm³ after 12 weeks; left arm – from 475·3 ± 79·1 cm³ to 493·2 ± 72·7 cm³ after 6 weeks and 511·3 ± 77·0 cm³ after 12 weeks). A high correlation was found between maximal muscle strength and muscle volume prior (r² = 0·62) and after (r² = 0·69) the training (P≤0·05). A self‐perceived MRT resulted in an increase in maximal and endurance strength. Morphological adaptation changes of triceps brachii as a result of 12‐week specific strength training can explain only up to 26% of strength gain.     

Effects of a high‐fat meal on resistance vessel reactivity and on indicators of oxidative stress in healthy volunteers

High fat meals postprandially impair macrovascular endothelial function and a link to increased oxidative stress is suggested. Few information, on the other hand, exists on the effect of postprandial hyperlipidaemia on resistance vessel function. Under normal circumstances this vascular bed regulates tissue perfusion and, by controlling flow, impacts on macrovascular nitric oxide formation. The impact of a high fat meal (1200 kcal, 90 g fat, 46 g protein and 47 g carbohydrates) on postprandial resistance vessel reactivity and on indicators of oxidative stress was studied in 11 healthy subjects by venous‐occlusion plethysmography using another six subjects as time control group. Ingestion of the test meal resulted in a pronounced increase of serum triglycerides from 1·05 ± 0·61 mmol l^?1 in the fasting state to peak postprandial values of 1·94 ± 0·41 mmol l^?1 (P < 0·001) reached after 4 h and a return to baseline after 8 h. Fasting peak reactive hyperaemia (RH) was 19·6 ± 2·4 ml min^?1 (100 ml)^?1. Two hours after ingestion of the test meal peak RH was transiently reduced to 16·8 ± 2·2 ml min^?1 (100 ml)^?1 (P < 0·05). No alteration of resting forearm perfusion was observed. The time course of peak RH suggested a potential biphasic effect of the test meal with an early impairment and a late increase of RH. Ingestion of a lipid rich test meal did not exert any influence on either total plasma antioxidant capacity given in trolox equivalents (513 ± 26 μmol l^?1 at baseline) or on plasma peroxides measured as H₂O₂ equivalents (469 ± 117 μmol l^?1). Our results suggest that ingestion of a meal containing 90 g of fat results in a transient impairment of reactive hyperaemia in healthy subjects but these vascular alterations are not accompanied by signs of systemically increased oxidative stress.     

Effects of varying central command and muscle mass on the cardiovascular responses to isometric exercise

To determine if the central command signal associated with isometric exercise is mass‐dependent, 20 subjects (nine male, 11 female; 23 ± 1 years) performed four 5‐min bouts of supine isometric exercise with a large (quadriceps; LEG) and small (forearm; ARM) muscle mass. For each extremity, one bout entailed maintaining a constant force (CF; 20% maximal voluntary contraction) and the other constant electromyographic activity (CE; ~20% MVC initially). Central command was assumed to increase with CF and remain unchanged with CE. Heart rate increased more with LEG than ARM (P<0·001) and, in LEG, was higher in CF than CE at min 5 (P<0·001). Mean arterial pressure was higher in LEG (P<0·001) by min 2 and 10 ± 3 mmHg higher in LEG CF than LEG CE by min 5 (P<0·001). Ratings of perceived exertion were highest in LEG CF (P<0·001); LEG CE did not differ from ARM CE (P<0·001) by min 4. The ARM responses did not differ between CF and CE in any variable. These data suggest that muscle mass influences the central command signal during isometric exercise and central command modulates this response in larger muscle masses.     

Effects of walking with blood flow restriction on limb venous compliance in elderly subjects

Venous compliance declines with age and improves with chronic endurance exercise. KAATSU, an exercise combined with blood flow restriction (BFR), is a unique training method for promoting muscle hypertrophy and strength gains by using low‐intensity resistance exercises or walking. This method also induces pooling of venous blood in the legs. Therefore, we hypothesized that slow walking with BFR may affect limb venous compliance and examined the influence of 6 weeks of walking with BFR on venous compliance in older women. Sixteen women aged 59–78 years were partially randomized into either a slow walking with BFR group (n = 9, BFR walk group) or a non‐exercising control group (n = 7, control group). The BFR walk group performed 20‐min treadmill slow walking (67 m min^?1), 5 days per week for 6 weeks. Before (pre) and after (post) those 6 weeks, venous properties were assessed using strain gauge venous occlusion plethysmography. After 6 weeks, leg venous compliance increased significantly in the BFR walk group (pre: 0·0518 ± 0·0084, post: 0·0619 ± 0·0150 ml 100 ml^?1 mmHg^?1, P<0·05), and maximal venous outflow (MVO) at 80 mmHg also increased significantly after the BFR walk group trained for 6 weeks (pre: 55·3 ± 15·6, post: 67·1 ± 18·9 ml 100 ml^?1 min^?1, P<0·01), but no significant differences were observed in venous compliance and MVO in the control group. In addition, there was no significant change in arm compliance in the BFR walk group. In conclusion, this study provides the first evidence that 6 weeks of walking exercise with BFR may improve limb venous compliance in untrained elder female subjects.     

Atrioventricular plane displacement correlates closely to circulatory dimensions but not to ejection fraction in normal young subjects

Aims Mitral atrioventricular plane displacement (AVPD) provides information about left ventricular systolic function. M‐mode of systolic annulus amplitude or tissue Doppler imaging of systolic annulus velocity are the current methods of evaluating AVPD. A correlation to ejection fraction (EF) has been demonstrated in patients with coronary artery disease and left ventricular dysfunction. Our aim was (i) to investigate the mitral AVPD of normal subjects with different physical work capacities and (ii) to further evaluate AVPD as an index of left ventricular systolic function. Methods and results Twenty‐eight healthy men mean age 28 years (20–39) were included: endurance trained (ET) (n=10), strength trained (ST) (n=9) and untrained (UT) (n=9). The systolic AVPD was recorded at four sites, septal, lateral, anterior and posterior, using M‐mode. Left ventricular volumes were calculated according to Simpson’s rule. Systolic AVPD was higher in endurance trained, 16·9 ± 1·5 mm, as compared with both strength trained, 13 ± 1·6 (P<0·001) and untrained, 14 ± 1·6 (P<0·001). Left ventricular systolic AVPD correlated strongly with end‐diastolic volume (r=0·82), stroke volume (r=0·80) and maximal oxygen consumption per body weight (r=0·72). The correlation between AVPD and EF was poor (r=0·22). Conclusion In the subjects studied, with a range of normal cardiac dimensions, AVPD correlated to stroke volume, end‐diastolic volume and maximal oxygen consumption per body weight, but not to EF. On theoretical grounds, it also seems reasonable that a dimension like AVPD is related to other cardiac dimensions and volumes, rather than to a fraction, like EF. AVPD is one parameter that is useful for evaluation of left ventricular systolic function but is not interchangeable with other measurements such as EF.     

Effects of rest intervals and training loads on metabolic stress and muscle hypertrophy

We investigated the effects of volume‐matched resistance training (RT) with different training loads and rest intervals on acute responses and long‐term muscle and strength gains. Ten subjects trained with short rest (30 s) combined with low load (20 RM) (SL) and ten subjects performed the same protocol with long rest (3 min) and high load (8 RM) (LH). Cross‐sectional area (CSA) of the upper arm was measured by magnetic resonance imaging before and after 8 weeks of training. Acute stress markers such as growth hormone (GH) and muscle thickness (MT) changes have been assessed pre and post a single RT session. Only the SL group demonstrated significant increases in GH (7704·20 ± 11833·49%, P<0·05) and MT (35·2 ± 16·9%, P<0·05) immediately after training. After 8 weeks, the arm CSA s in both groups significantly increased [SL: 9·93 ± 4·86% (P<0·001), LH: 4·73 ± 3·01% (P<0·05)]. No significant correlation between acute GH elevations and CSA increases could be observed. We conclude that short rest combined with low‐load training might induce a high amount of metabolic stress ultimately leading to improved muscle hypertrophy while long rest with high‐load training might lead to superior strength increases. Acute GH increases seem not to be directly correlated with muscle hypertrophy.     

Increased sympathetic tone in forearm subcutaneous tissue in primary hypothyroidism

Summary. Sympathetic reflex regulation of subcutaneous blood flow (SBF) in the forearm was studied in eight patients with primary hypothyroidism. Diastolic arterial pressure was ≥95 mmHg in five patients. SBF was determined by local clearance of Na^99mTcO₄. Sympathetic vasoconstriction normally seen after lowering the forearm 40 cm below heart level was absent since SBF only decreased by 4% (± 7%, P > 0·1) during these conditions. In head-up vertical position we noticed a diminished baroreceptor response as SBF at heart level was reduced by 11% (±7%, P < 0·1) compared to supine position. After proximal local anaesthesia SBF increased by 351% (±81%, P < 0·01) and disclosed a normal vasoconstrictor response as SBF was reduced by 53% (±5%, P < 0·01) during arm lowering. Five of the treated patients were restudied in the euthyroid state. Mean arterial pressure was reduced in mean by 20 mmHg (± 6 mmHg, P < 0·02) during treatment and a significant vasoconstriction was observed both during arm lowering (SBF =-52% (±6%, P<0·02)) and in head-up vertical position (SBF= -45% (± 11%, P<0·02)). In conclusion sympathetic vasoconstrictor activity in adipose tissue is markedly increased in primary hypothyroidism. Sympathetic tone and arterial pressure are reduced during treatment.     

Leg uptake of calcitonin gene‐related peptide during exercise in spinal cord injured humans

Exercise‐induced increases in cardiac output (CO) and oxygen uptake (VO₂) are tightly coupled, as also in absence of central motor activity and neural feedback from skeletal muscle. Neuromodulators of vascular tone and cardiac function – such as calcitonin gene related peptide (CGRP) – may be of importance. Spinal cord injured individuals (six tetraplegic and four paraplegic) performed electrically induced cycling (FES) with their paralyzed lower limbs for 29 ± 2 min to fatigue. Voluntary cycling performed both at VO₂ similar to FES and at maximal exercise in six healthy subjects served as control. In healthy subjects, CGRP in plasma increased only during maximal exercise (33·8 ± 3·1 pmol l^?1 (rest) to 39·5 ± 4·3 (14%, P<0·05)) with a mean extraction over the working leg of 10% (P<0·05). Spinal cord injured individuals had more pronounced increase in plasma CGRP (33·2 ± 3·8 to 46·9 ± 3·6 pmol l^?1, P<0·05), and paraplegic and tetraplegic individuals increased in average by 23% and 52%, respectively, with a 10% leg extraction in both groups (P<0·05). The exercise induced increase in leg blood flow was 10–12 fold in both spinal cord injured and controls at similar VO₂ (P<0·05), whereas CO increased more in the controls than in spinal man. Heart rate (HR) increased more in paraplegic subjects (67 ± 7 to 132 ± 15 bpm) compared with controls and tetraplegics (P<0·05). Mean arterial pressure (MAP) was unchanged during submaximal exercise and increased during maximal exercise in healthy subjects, but decreased during the last 15 min of exercise in the tetraplegics. It is concluded that plasma CGRP increases during exercise, and that it is taken up by contracting skeletal muscle. The study did not allow for a demonstration of the origin of the CGRP, but its release does not require activation of motor centres. Finally, the more marked increase in plasma CGRP and the decrease in blood pressure during exercise in tetraplegic humans may indicate a role of CGRP in regulation of vascular tone during exercise.     

Forearm skin tissue dielectric constant measured at 300 MHz: effect of changes in skin vascular volume and blood flow

Skin tissue dielectric constant (TDC) values measured via the open‐ended coaxial probe method are useful non‐invasive indices of local skin tissue water. However, the effect of skin blood flow (SBF) or skin blood volume (SBV) on TDC values is unknown. To determine the magnitude of such effects, we decreased forearm SBV via vertical arm raising for 5 min (test 1) and increased SBV by bicep cuff compression to 50 mmHg for 5 min (test 2) in 20 healthy supine subjects (10 men). TDC values were measured to a depth of 1·5 mm on anterior forearm, and SBF was measured with laser‐Doppler system simultaneously on forearm and finger. Results indicate that decreasing vascular volume (test 1) was associated with a small but statistically significant reduction in TDC (3·0 ± 4·3%, P = 0·003) and increasing vascular volume (test 2) was associated with a slight but statistically significant increase in TDC (3·5 ± 3·0%, P<0·001). SBF changes depended on test and measurement site. For forearm, test 1 significantly increased SBF (102·6 ± 156·2%, P<0·001) and test 2 significantly decreased it (39·5 ± 13·1%, P<0·001). In finger, SBF was significantly reduced by both tests: in test 1 by 55·3 ± 32·1%, P<0·001 and in test 2 by 53·3 ± 27·6%, P<0·001. We conclude that the small percentage changes in TDC values (3·0–3·5%) over the wide range of induced SBV and SBF changes suggest a minor effect on clinically determined TDC values because of SBV or SBF changes or differences when comparing TDC longitudinally over time or among individuals of different groups in a research setting.     

Relationship between ultrasound muscle thickness and MRI‐measured muscle cross‐sectional area in the forearm: a pilot study

Previous studies have investigated the relationship between ultrasound‐measured muscle thickness (MT) and individual muscle cross‐sectional area (CSA); however, the forearm muscle had not yet been studied. The purpose of this study was to examine the relationship between forearm MT by ultrasound and the muscle CSA of the forearm obtained by magnetic resonance imaging (MRI). Ten young and middle‐aged adults had both ultrasound and MRI measurements at 30% the distance from the styloid process of the ulna to the head of the radius. Handgrip strength (HGS) was also measured. Strong correlations (P<0·001) were observed between MRI‐measured muscle CSA (total and flexor and extensor components) and MT‐ulna (ranged r = 0·937–0·946) and MT‐radius (ranged r = 0·884–0·891). HGS was also correlated (P<0·001) with forearm MT (MT‐ulna, r = 0·877; MT‐radius, r = 0·852) and MRI‐measured muscle CSA (flexor CSA, r = 0·910; extensor CSA, r = 0·923). Our results suggest that forearm MT is closely associated with MRI‐measured forearm muscle CSA in young and middle‐aged adults and suggest that ultrasound‐measured forearm muscle thickness may be a useful variable for evaluating muscle CSA and function in the forearm.     

Effects of resistance training on cardiovascular responses to lower body negative pressure in the elderly

The purpose of the present study was to determine whether resistance training alters the cardiovascular responses to submaximal lower body negative pressure (LBNP) in the elderly. Twenty‐one subjects were randomized into a control (C: n=10; 70 ± 3 years, mean ± SD) or a resistance training (TR: n=11; 67 ± 7 years) group. Subjects in the TR underwent 12 weeks of training consisting of three sets of 8–12 contractions at ?60–80% of their initial maximal one repetition, three times per week, on 10 different machines. Before (Pre) and after (Post) training, all subjects underwent exposures of LBNP of ?10, ?20 and ?40 Torr and muscle biopsy sampling at the vastus lateralis. TR increased (P≤0·05) knee extension (Pre=379 ± 140 N, Post=534 ± 182 N) and chest press (Pre=349 ± 137 N, Post=480 ± 192 N) strength. Neither body weight nor percentage body fat were altered (P >0·05) by training. Resistance training increased (P≤0·05) cross‐sectional area in both Type I (4203 ± 1196 to 5248 ± 1728 μm²) and Type II (3375 ± 1027 to 4286 ± 1892 μm²) muscle fibres. Forearm blood flow, forearm vascular conductance, mean arterial pressure, and heart‐rate responses to LBNP were not altered by the training. These data suggest that the cardiovascular responses of elderly to LBNP are unaffected by 12 weeks of whole‐body resistance training despite increases in muscle strength and size.     

Postprandial impairment of resistance vessel function in insulin treated patients with diabetes mellitus type‐2

Reduced postischaemic reactive hyperaemia, is considered a marker of impaired resistance vessel function. Acute postprandial hyperlipidaemia has been shown to induce vascular dysfunction. In the present study, the impact of postprandial hyperglycaemia on resistance vessel reactivity was investigated in insulin treated type‐2 diabetic patients. The study was performed in 16 insulin treated type‐2 diabetics (eight male/eight female, age 47 ± 3 years, HbA1c 7·2 ± 0·2) and 16 controls. Reactive hyperaemia was measured in the forearm by venous occlusion plethysmography after 5 min of ischaemia in the fasting state and 90 min after a test meal. In diabetics, blood glucose increased from 8·7 ± 1·1 to 15·3 ± 1·0 mmol l^?1 (P<0·001) postprandially. This resulted in (i) a significant increase of resting blood flow (3·4 ± 0·3 to 4·8 ± 0·4 ml min^?1 100 ml^?1, P<0·01) and (ii) in a reduced peak reactive hyperaemia (52·3 ± 7·4 to 36·8 ± 4·3 ml min^?1 100 ml^?1, P<0·005). In controls, a similar effect of the meal on resting flow was observed but reactive hyperaemia was unaltered. In the absence of a test meal, basal flow as well as peak reactive hyperaemia remained unchanged in diabetic as well as in non‐diabetic subjects. Our data provide evidence that in the postprandial state resistance vessel reactivity becomes reduced in insulin treated type‐2 diabetic patients.