Neuromuscular adaptations to water-based concurrent training in postmenopausal women: effects of intrasession exercise sequence

This study investigated the effects of different exercise sequences on the neuromuscular adaptations induced by water-based concurrent training in postmenopausal women. Twenty-one healthy postmenopausal women (57.14 ± 2.43 years) were randomly placed into two water-based concurrent training groups: resistance training prior to (RA, n = 10) or after (AR, n = 11) aerobic training. Subjects performed resistance and aerobic training twice a week over 12 weeks, performing both exercise types in the same training session. Upper (elbow flexors) and lower-body (knee extensors) one-repetition maximal test (1RM) and peak torque (PT) (knee extensors) were evaluated. The muscle thickness (MT) of upper (biceps brachii) and lower-body (vastus lateralis) was determined by ultrasonography. Moreover, the maximal and submaximal (neuromuscular economy) electromyographic activity (EMG) of lower-body (vastus lateralis and rectus femoris) was measured. Both RA and AR groups increased the upper- and lower-body 1RM and PT, while the lower-body 1RM increases observed in the RA was greater than AR (34.62 ± 13.51 vs. 14.16 ± 13.68 %). RA and AR showed similar MT increases in upper- and lower-body muscles evaluated. In addition, significant improvements in the maximal and submaximal EMG of lower-body muscles in both RA and AR were found, with no differences between groups. Both exercise sequences in water-based concurrent training presented relevant improvements to promote health and physical fitness in postmenopausal women. However, the exercise sequence resistance–aerobic optimizes the strength gains in lower limbs.     

Central adaptations to exercise training in patients with chronic heart failure

In chronic heart failure patients, the increase of peak VO₂ observed after a period of aerobic training is currently attributed more to peripheral (skeletal muscle) than central (heart) adaptations. This paper reviews the current scientific evidence regarding the existence or the absence of significant training-induced adaptations of peak cardiac output and its determinants in patients with chronic heart failure due to left ventricular systolic dysfunction. It is concluded that, on the basis of available literature, a training-induced significant increase of peak cardiac output with respect to pre-training values does exist in the chronic heart failure population. Such an effect is due to adaptations of the main cardiac output determinants, that is, heart rate and stroke volume, whose relative contribution to the cardiac output increase will vary in the single patient due to variability in the individual response to the training stimulus. Moreover, these data emphasize both the safety and even the central morpho-functional benefits of aerobic training programs in the chronic heart failure population, setting the stage for an even more widespread use of this non-pharmacologic intervention in the everyday clinical practice. As most studies considered in this review were conducted in the pre-beta-blockers era, the possibility to extend the conclusions of this paper to chronic heart failure patients on beta-blocking therapy remains to be verified.     

Rapid onset and offset of circulatory adaptations to exercise training in men

Chronic aerobic exercise lowers blood pressure (BP), peripheral resistance and cardiac work, and is used widely in antihypertensive and cardiac rehabilitation programmes. In this study, we tested the hypothesis that the cardiovascular benefits of training would occur progressively over several weeks and would diminish over a similar time course on termination of training. In all, 17 young, healthy men undertook a 4-week programme of cycle ergometry (30 min at 60% VO2peak 3-4 times/week) and 13 subjects matched for age, body mass index and fitness acted as controls. Resting BP and rate-pressure product (RPP) had fallen significantly after only 1 week's training and reached a nadir after 2 weeks training. At this time, BP had fallen from 121+/-7/66+/-6 to 110+/-5/57+/-7 mmHg and resting RPP had fallen from 85+/-10 to 71+/-9 (mmHg (beats min-1))-2 (P<0.001 each). In parallel, resting forearm conductance had risen from 0.026+/-0.010 to 0.052+/-0.029 (ml min-1) 100 ml-1 mmHg-1 and peak reactive hyperaemia following 3 min brachial artery occlusion was increased from 0.105+/-0.031 to 0.209+/-0.041 (ml min-1) 100 ml-1 mmHg-1 (P<0.001 each). No significant further circulatory changes occurred over weeks 3-4 of training. On cessation of training, all values returned to pretraining levels within between 1 (SBP, RPP, vascular conductance) and 2 (DBP, MAP, heart rate, reactive hyperaemia) weeks. The results indicate that the optimal cardiovascular benefits of moderate exercise occur rapidly. At least with short training programmes, the benefits regress once training stops just as quickly as they appeared.     

Metabolic adaptations to exercise: a review of potential beta-adrenoceptor antagonist effects

Human skeletal muscle contains 2 muscle fiber types: slow twitch (type I) and fast twitch (type II). They have different profiles including their biochemical, metabolic, O2 diffusion, microcirculatory and neuromotor characteristics. The slow twitch fiber represents endurance, high combustive potential and recruitment during moderate activity; in contrast, the fast twitch represents explosiveness, force, high capacity for phosphate splitting and lactate formation, but is more fatiguable. A muscle rich in slow twitch fibers is confined to low peripheral resistance at rest and during exercise, higher exercise leg blood flow and higher maximal oxygen uptake (VO2 max). During graded exercise lactate has been shown to be a good marker for the metabolic and circulatory characteristics of the contracting muscle and the exercise intensity (W) eliciting a blood lactate concentration of 4 mmol/liter-1 [(WOBLA) from onset of blood lactate accumulation] integrated for peripheral metabolic, neuromotor and central circulatory potentials both in health and disease. It is well known that a blood lactate level greater than 4 mmol/liter-1 represents a major increase in sympathetic tone and is incompatible with endurance or prolonged exercise. With prolonged exercise and sympathetic regulation both circulation and metabolism adapt. Adipose tissue is stimulated and fatty acids are released. Muscle tissue lipoprotein lipase activity is enhanced; that is, there is increased utilization of blood triglycerides for local lipolysis in the capillary bed of the contracting muscle. Both mechanisms will increase fatty acid availability and induce a "glycogen-sparing effect" resulting in a reduced respiratory exchange ratio. Studies have shown that both the magnitude of the initial glycogen stores and these adaptive responses will determine performance time. With age, changes take place in heart rate regulation, neuromotor control and muscle fibers. Thus VO2 max is decreased, but partly compensated for by a fast motor unit and fiber loss leading to a muscle more rich in slow twitch fibers--an "endurance training-like effect." Relative endurance is also increased with age; however, lactate metabolism is still a critical feature. The OBLA concept describes capacity for both occupational and leisure-time physical activity.     

Biochemical changes in response to intensive resistance exercise training in the elderly

BACKGROUND: It is assumed that low-grade inflammation, characterized by increased circulating IL-6 and TNF-alpha, is related to the development of sarcopenia. Physical exercise, especially high intensity resistance training, has been shown to be effective in restoring the strength deficit in the elderly. Intensive exercise is accompanied by significant release of IL-6 and TNF-alpha into the blood circulation, but does not result in muscle wasting. Exercise-induced changes in heat-shock protein (Hsp), responsible for cellular protection during stressful situations, might interfere with the acute phase reaction and muscle adaptation. OBJECTIVE: To investigate if intensive strength training in elderly persons induces changes in Hsp70 expression, and if these changes are related to changes in the acute phase reaction or muscle adaptation. METHODS: 31 elderly persons (aged 68.4+/-5.4 years) performed 6 weeks' intensive strength training. At baseline and after 6 weeks, muscle strength, functional performance (physical activity profile, 6-min walk, 30- second chair stand, grip strength, chair sit & reach and back scratch), linear isokinetic leg extension, circulating IL-6, TNF-alpha, IL-10 and TGF-beta, and Hsp70 in monocytes (M) and lymphocytes (L) immediately after sampling (IAS), after incubation at 37 and 42 degrees C were determined. In 12 participants, cytokines were determined in untrained and trained conditions before and after a single training session. RESULTS: After 6 weeks' training, muscle strength and functional performance improved significantly, together with decreased Hsp70 IAS and Hsp70 37 degrees C and increased Hsp70 42 degrees C (all p<0.05). Strength gains correlated positively with baseline Hsp70 37 degrees C and training-induced changes of Hsp70 42 degrees C in M and L. In an untrained condition, training induced an increase of IL-6 (p<0.05) and a tendency of IL-10 to decrease (p=0.06). In a trained condition the decrease of IL-10 disappeared. Baseline physical activity and 6-min walk distance correlated negatively with circulating IL-6 (p<0.05); except for a negative correlation between TGF-beta and Hsp70 37 degrees C L (p<0.05), no significant relationships were found between cytokines and Hsp70. After the training program, Hsp70 37 degrees C was negatively related to circulating TNF-alpha, IL-10 and TGF-beta. CONCLUSION: Strength training in the elderly induces changes in Hsp70 expression, associated to strength gains and circulating cytokines.     

Efficiency of twice weekly concurrent training in trained elderly men

This study compared the effects of different weekly training frequencies on the cardiovascular and neuromuscular adaptations induced by concurrent training in previously trained elderly. After 20 weeks of combined strength and endurance training, twenty-four healthy elderly men (65 ± 4 years) were randomly placed into two frequency training groups: strength and endurance training performed twice a week (SE2, n = 12); or, strength and endurance training performed three times per week (SE3, n = 12). The interventions lasted 10 weeks and each group performed identical exercise intensity and volume per session. Before and after the exercise training, one maximum repetition test (1RM), isometric peak torque (PT), maximal surface electromyographic activity (EMG), as well as muscle thickness (MT) were examined. Additionally, peak oxygen uptake (VO_2peak), maximum aerobic workload (W_max), first and second ventilatory thresholds (VT₁ and VT₂) were evaluated. There were significant increases in upper and lower-body 1RM, MT, VO_2peak, VT₁ and VT₂, with no differences between groups. There were no changes after training in maximal EMG and isometric peak torque. W_max was improved only in SE3. After 10 weeks of training, twice weekly combined strength and endurance training leads to similar neuromuscular and cardiovascular adaptations as three times per week, demonstrating the efficiency of lower frequency of concurrent training in previously trained elderly men.     

Endurance exercise training increases adipose tissue glucocorticoid exposure: adaptations that facilitate lipolysis

Glucocorticoids (GCs) have long been thought to be lipolytic in nature. Recently, however, increased exposure to GCs in insulin-sensitive tissues has been associated with lipid accumulation and metabolic complications, regardless of plasma concentrations. Intracellular GC action is determined by both 11-β hydroxysteroid dehydrogenase type 1 (11βHSD1) and the GC receptor (GR). We hypothesized that exercise training would increase 11βHSD1 and GR protein in adipose tissue, resulting in increased lipolysis. To test the effects of exercise on adipose tissue GR and 11βHSD1 protein, 2 sets of hamsters were trained for 6 weeks: young, diet-induced obese animals and older, overweight animals. Young (6 week old) hamsters, fructose-fed to induce an obese phenotype, and older (6 month old) hamsters were randomly divided into exercising and sedentary groups. Exercise training decreased adipose tissue mass in both fructose-fed and older hamsters. In addition, exercise training increased 11βHSD1 (31.5% ± 15% and 20.0% ± 7%, fructose-fed and older, respectively) and GR (45.6% ± 14% and 61.1% ± 27%, fructose-fed and older, respectively) protein expression in the perirenal adipose depot and increased 11βHSD1 (16.7% ± 7%, P = .09) and GR (47.4% ± 19%, P < .05) in the subcutaneous adipose depot of the older hamsters. To determine the metabolic effect of increased GC exposure in adipocytes, 3T3-L1 adipocytes were treated with corticosterone for 24 hours; and measures of lipolytic rates were conducted. Low concentrations of GCs (0.01-0.1 μmol/L) increased GR (44.1% ± 18%, P < .05) and 11βHSD1 (95.3% ± 24%) protein expression, as well as lipolytic rates (34.6% ± 6%) as measured by glycerol release. The increased lipolysis was blocked by RU486, a GR antagonist, suggesting that the elevated lipolysis was a direct result of GC action. These results suggest that exercise training amplifies the activity of GCs in adipose tissue of overweight animals through alterations in 11βHSD1 and GR despite differences in age and amounts of adiposity. In vitro, GCs are capable of increasing lipolysis, but depend upon the presence of GR. We propose that GCs play a significant role in changing the phenotype of adipose tissue during exercise training, resulting in decreased fat mass.     

Cardiac adaptations to training: relevance to angina pectoris

Exercise training has for many years been suggested as a useful adjunct to medical therapy for patients with ischaemic heart disease. While its popularity amongst the general public continues to grow, limitations in our ability to assess its effects on the heart have meant that, as cardiologists, our desire to encourage this popular upsurge in physical activity has been tempered by our inability to provide convincing evidence of its value to our patients. In particular the role of exercise in the rehabilitation of patients with angina pectoris is as yet unclear. This review addresses this question and states what has been proven to date and also the questions which remain to be answered. It also suggests some reasons why we have failed to provide answers so far, and ways in which new technology may be used in the future. Studies in animals, asymptomatic humans, and patients with ischaemic heart disease have demonstrated that training reduces the resting heart rate and double product of heart rate times blood pressure at any given level of exercise. This has the benefit of reducing myocardial oxygen consumption during exercise. There is also evidence that it increases end-diastolic volume and left ventricular wall thickness. Evidence for an increase in maximal myocardial oxygen consumption in angina is limited to one or two studies showing an improved maximum double product and to the occasional patient proven by echocardiography or nuclear studies to increase ejection fraction by training. Better selection of patients and use of new imaging techniques should provide further information in the near future.     

Impaired fibrinolytic response to exercise in type II diabetes: effects of exercise and physical training

We studied the effects of exercise and physical training on coagulation parameters and fibrinolytic activity in 16 sedentary non-insulin-dependent diabetics and nine control subjects matched for prior physical activity. Parameters were measured at rest and after 30 minutes of bicycle exercise at 70% to 75% of maximal oxygen uptake before and after 6 weeks of thrice-weekly physical training. In the untrained state, fibrinolytic activity was impaired in diabetics compared with controls (1.26 +/- 0.19 v 2.20 +/- 0.34 U; P less than .03), and resting levels of plasma fibrinogen (329 +/- 21 v 266 +/- 17 mg/dL; P less than .01) and the prothrombin time (PT) maximal velocity (Vmax) (4.9 +/- 0.5 v 2.9 +/- 0.5; P less than .05) were increased. The activated partial thromboplastin time (APTT) Vmax was also increased but this did not reach statistical significance (3.6 +/- 0.2 v 2.3 +/- 0.5; P less than 0.10). Activation of fibrinolysis occurred following exercise in both groups but the peak activity and increment were less in diabetics. Physical training for 6 weeks had no effect on plasma fibrinogen levels but significantly improved the resting and postexercise APTT Vmax and resting fibrinolytic activity in diabetics. The exercise-induced increment in fibrinolytic activity following training remained depressed compared with normal controls. The changes in APTT Vmax correlated with changes in the indices of blood glucose control. The relevance of these findings to possible antiatherogenic effects of exercise and the mechanism by which exercise produces these effects remain to be established.     

Hemorheological and cardiovascular effects of exercise training in the rehabilitation of elderly patients with chronic obstructive pulmonary disease

The purpose of this study is to evaluate hemorheological effects of a single exercise respiratory session (SERS), in the rehabilitation of elderly patients with chronic obstructive pulmonary disease (COPD). Fifteen elderly patients with COPD and 15 controls, matched for demographic variables and body habitus, were submitted to a single session of relaxation and unsupported upper-extremity exercise, coordinated with breathing. We measured hemogasanalytical and cardiovascular parameters: hematocrit value, platelet aggregation, beta-TG and PF(4) plasma levels, blood viscosity and erythrocyte filterability. In both groups, SERS significantly decreased platelet aggregation (P<0.05), beta-TG and PF(4) plasma levels (P<0.05). Erythrocyte filterability and diastolic blood pressure showed a trend to increase in both groups but reached a significant difference in patients with COPD only. Respiratory exercise has a positive influence on platelet and hemorheological parameters in the elderly with COPD. The increase of diastolic blood pressure requires active surveillance.     

Long-term effects of memory training in the elderly: a longitudinal study

The effects of different types of memory training in young and older adults reported in a previous study [Cavallini, E., Pagnin, A., Vecchi, T., 2003. Aging and everyday memory: the beneficial effect of memory training. Arch. Gerontol. Geriatr. 37, 241-257] were again investigated from a longitudinal perspective 2 years after the original memory training sessions. The authors retested the original participants to measure the long-term effectiveness of two mnemonic strategies: the loci technique and strategic training. Three groups of participants (13 adults, M=24.1, 13 younger elderly, M=64.2 and 13 older elderly, M=74.4) were tested using a battery of seven tasks and four questionnaires, to evaluate memory performance and metamemory variables. The three age groups and the two trainings showed similar results on memory performance. Long-term effects were found only on two memory tasks, both were highly related to everyday life showing that, without additional practice, memory performance tended to go back to the original level. Moreover, the beneficial effects of the previous training sessions were particularly evident for older adults in metamemory knowledge and for strategic training in memory complaints. Results partially support the durability of memory training in improving memory performance.     

Hemodynamic effects of exercise training in heart failure

Background

Exercise performance improvement after training in heart failure (HF) can be due to central or peripheral changes.

Methods and Results

In 70 HF stable patients we measured peak VO₂ and cardiac output (CO, inert gas rebreathing technique) and calculated arteriovenous O₂ differences (a-v O₂diff) before and after an 8-week training program. Peak VO₂ changed from 1111 ± 403 mL/minute to 1191 ± 441 (P < .001), peak workload from 68 ± 29 watts to 76 ± 32 (P < .0001), peakCO from 6.6 ± 2.2 L/minute to 7.3 ± 2.5 (P < .0001), and peak a-v O₂diff from 17.5 ± 5.1 mL/100 mL to 16.6 ± 4.1 (P = .081). Changes in peak CO and a-v O₂diff allowed to identify 4 behaviors: group 1: (n = 15) reduction in peak CO and increase in a-v O₂diff (peak VO₂ unchanged, peak workload +9.5%); group 2: (n = 16) both peak CO and a-v O₂diff increased as well as peak VO₂ (23%) and workload (18%); group 3: (n = 4) peak CO and a-v O₂diff reduced as well as peak VO₂ (-18%) and workload (-5%); group 4: (n = 35) peak CO increased with a-v O₂diff reduced (increase in peak VO₂ by 5.5 and workload by 8.4%).

Conclusions

Exercise training improves peakVO₂ by increasing CO with unchanged a-v O₂diff. A reduction after training of a-v O₂diff with an increase in CO is frequent (50% of cases), is suggestive of blood flow redistribution and, per se, not a sign of reduced muscle performance been associated with improved exercise capacity.