The effects of water-based circuit exercise training on vascular function in people with coronary heart disease

Impaired endothelial function in people with coronary heart disease (CHD) is associated with increased mortality. Water immersion can increase peripheral artery shear stress which may provide an additional stimulus to the endothelium during exercise. This study compared the effects of water-based circuit exercise training (WEX) and gym-based circuit exercise training (GEX) on vascular function in people with stable CHD. Participants were randomized to 12 wk of WEX (n = 20), GEX (n = 20), or a control group (usual activities; n = 12). Endothelium-dependent flow-mediated dilation (FMD) and glyceryl trinitrate-mediated dilation (GTN) of the brachial artery were assessed pre- and postintervention. FMD increased following WEX [4.0% (3.0%-5.1%) to 5.3% (4.1%-6.5%); P = 0.016], but was unchanged following GEX [4.9% (3.8%-5.9%) to 5.0% (3.8%-6.1%); P = 0.822]. There were no between-group differences in the change in FMD and no significant changes in GTN-mediated dilation percentage. Triglycerides decreased following GEX [1.2 mmol·L-1 (1.0-1.4 mmol·L-1) to 1.0 mmol·L-1 (0.8-1.3 mmol·L-1); P = 0.022], but there were no further differences in lipid profiles. WEX improved endothelial function of the brachial artery in people with stable CHD, suggesting that WEX is an effective alternative to gym-based exercise in people living with CHD, which may specifically address vascular health.NEW & NOTEWORTHY This study found that 12 wk of water-based circuit exercise training was well tolerated and improved vascular endothelial function in people with stable coronary heart disease. However, there was no effect on endothelium-independent function. Water-based exercise appears to be an effective alternative to gym-based exercise for people with coronary heart disease, which has specific benefits to vascular health and function.

Effects of testosterone treatment, with and without exercise training, on ambulatory blood pressure in middle-aged and older men

CONTEXT

With age, testosterone (T) and physical activity levels often decline in parallel. The effect of combining T treatment and exercise training on ambulatory blood pressure (ABP) is unclear.

OBJECTIVE

To assess T and exercise effects, alone and in combination, on ABP in men aged 50-70 years, waist circumference ≥ 95 cm and low-normal serum T (6-14 nmol/L), without organic hypogonadism.

DESIGN

A 2 × 2 factorial randomised, placebo-controlled study.

INTERVENTION

Randomization to daily transdermal AndroForte5^® (Testosterone 5.0%w/v, 100 mg in 2 ml) cream (T), or matching placebo (P) (double-blind), and to supervised exercise (Ex) or no additional exercise (NEx), for 12 weeks.

RESULTS

Average 24-h systolic blood pressure (SBP) increased with T treatment (testosterone*time, p = .035). Average 24-h SBP increased in T+Ex (T+Ex:+3.0 vs. P+NEx: -3.0 mmHg, p = .026) driven by day-time changes (T+Ex:+3.5 vs. P+NEx: -3.0 mmHg, p = .026). There was an effect of T for 24-h average diastolic blood pressure (DBP, testosterone*time, p = .044) driven by the decrease in P+Ex (P+Ex: -3.9 vs. T+NEx: -0.5 mmHg, p = .015). Night-time DBP was lower with exercise (P+Ex: -4.0 vs. P+NEx: +0.7 mmHg, p = .032). The effect of exercise to lower night-time DBP was not apparent in the presence of T (T+Ex: -0.4 vs. P+NEx: +0.7 mmHg, p > .05). Ex increased average 24-h pulse pressure (PP, exercise*time, p = .022), largely during daytime hours (exercise*time, p = .013).

CONCLUSIONS

There was a main effect of T to increase 24-h SBP, primarily seen when T was combined with Ex. Exercise alone decreased 24-h and night-time DBP; an effect attenuated by T. BP should be carefully assessed and monitored, when prescribing T treatment to middle-aged and older men, especially when combined with exercise training.

Testosterone and exercise: effects on fitness, body composition, and strength in middle-to-older aged men with low-normal serum testosterone levels

As men age, serum testosterone (T) concentrations decrease, as do fitness, strength, and lean mass. Whether testosterone treatment confers additive benefit to reverse these changes when combined with exercise training in middle-to-older aged men remains unclear. We assessed the effects of T treatment and exercise, alone and in combination, on aerobic capacity (V̇o₂peak), body composition, and muscular strength in men 50-70 yr, waist circumference ≥95 cm and low-normal serum T (6-14 nmol·L^-1). Participants (n = 80) were randomized to AndroForte5 (testosterone 5.0% wt/vol, 100 mg/2 mL) cream (T), or matching placebo (P), applied transdermally daily, and supervised center-based exercise (Ex) or no additional exercise (NEx), for 12-wk. Exercise increased V̇o_2peak and strength versus nonexercise (V̇o_2peak: T + Ex: +2.5 mL·kg^-1·min^-1, P + Ex: +3.2 mL·kg^-1·min^-1, P < 0.001; leg press: T + Ex: +31 kg, P + Ex: +24 kg, P = 0.006). T treatment did not affect V̇o_2peak or strength. Exercise decreased total (T + Ex: -1.7, P + Ex: -2.3 kg, P < 0.001) and visceral fat (T + Ex: -0.1 kg, P + Ex: -0.3 kg, P = 0.003), and increased total (T + Ex: +1.4 kg, P + Ex: +0.7 kg, P = 0.008) and arm lean mass (T + Ex: +0.5 kg, P + Ex: +0.3 kg, P = 0.024). T treatment did not affect total or visceral fat, but increased total (T + Ex: +1.4 kg, T + NEx: +0.7 kg, P = 0.015), leg (T + Ex: +0.3 kg, T + NEx: +0.2 kg, P = 0.024), and arm lean mass (T + Ex: +0.5 kg, T + NEx: +0.2 kg, P = 0.046). T + Ex increased arm lean mass (T + Ex: +0.5 kg vs. P + NEx: -0.0 kg, P = 0.001) and leg strength (T + Ex: +31 kg vs. P + NEx: +12 kg, P = 0.032) compared with P + NEx, with no other additive effects. Exercise training was more effective than T treatment in increasing aerobic capacity and decreasing total and visceral fat mass. T treatment at therapeutic doses increased lean mass but conferred limited additional benefit when combined with exercise. Exercise should be evaluated as an antiaging intervention in preference to testosterone treatment in men.NEW & NOTEWORTHY We illustrate that exercise training generates superior outcomes to testosterone treatment for improving aerobic fitness, muscular strength, and total and visceral fat mass in men 50-70 yr with low-normal serum testosterone concentrations. Adding testosterone treatment to exercise did not provide any additive benefit for these variables. Testosterone treatment alone and exercise alone had similar impacts on lean mass. Therefore, men unable to exercise may obtain benefit from testosterone treatment alone to improve lean mass.

Testosterone and Exercise in Middle-to-Older Aged Men: Combined and Independent Effects on Vascular Function

[Figure: see text].

Exercise Intolerance, Benefits, and Prescription for People Living With a Fontan Circulation: The Fontan Fitness Intervention Trial (F-FIT)-Rationale and Design

Background: Despite developments in surgical techniques and medical care, people with a Fontan circulation still experience long-term complications; non-invasive therapies to optimize the circulation have not been established. Exercise intolerance affects the majority of the population and is associated with worse prognosis. Historically, people living with a Fontan circulation were advised to avoid physical activity, but a small number of heterogenous, predominantly uncontrolled studies have shown that exercise training is safe-and for unique reasons, may even be of heightened importance in the setting of Fontan physiology. The mechanisms underlying improvements in aerobic exercise capacity and the effects of exercise training on circulatory and end-organ function remain incompletely understood. Furthermore, the optimal methods of exercise prescription are poorly characterized. This highlights the need for large, well-designed, multi-center, randomized, controlled trials. Aims and Methods: The Fontan Fitness Intervention Trial (F-FIT)-a phase III clinical trial-aims to optimize exercise prescription and delivery in people with a Fontan circulation. In this multi-center, randomized, controlled study, eligible Fontan participants will be randomized to either a 4-month supervised aerobic and resistance exercise training program of moderate-to-vigorous intensity followed by an 8-month maintenance phase; or usual care (control group). Adolescent and adult (≥16 years) Fontan participants will be randomized to either traditional face-to-face exercise training, telehealth exercise training, or usual care in a three-arm trial with an allocation of 2:2:1 (traditional:telehealth:control). Children (<16 years) will be randomized to either a physical activity and exercise program of moderate-to-vigorous intensity or usual care in a two-arm trial with a 1:1 allocation. The primary outcome is a change in aerobic exercise capacity (peak oxygen uptake) at 4-months. Secondary outcomes include safety, and changes in cardiopulmonary exercise testing measures, peripheral venous pressure, respiratory muscle and lung function, body composition, liver stiffness, neuropsychological and neurocognitive function, physical activity levels, dietary and nutritional status, vascular function, neurohormonal activation, metabolites, cardiac function, quality of life, musculoskeletal fitness, and health care utilization. Outcome measures will be assessed at baseline, 4-months, and 12-months. This manuscript will describe the pathophysiology of exercise intolerance in the Fontan circulation and the rationale and protocol for the F-FIT.

Cerebral blood flow responses to exercise are enhanced in left ventricular assist device patients after an exercise rehabilitation program

Cerebral blood flow during exercise is impaired in patients with heart failure implanted with left ventricular assist devices (LVADs). Our aim was to determine whether a 3-mo exercise training program could mitigate cerebrovascular dysfunction. Internal carotid artery (ICA) blood flow and intracranial middle (MCAv) and posterior cerebral (PCAv) artery velocities were measured continuously using Doppler ultrasound, alongside cardiorespiratory measures at rest and in response to an incremental cycle ergometer exercise protocol in 12 LVAD participants (5 female, 53.6 ± 11.8 yr; 84.2 ± 15.7 kg; 1.73 ± 0.08) pre- (PreTR) and post- (PostTR) completion of a 3-mo supervised exercise rehabilitation program. At rest, only PCAv was different PostTR (38.1 ± 10.4 cm/s) compared with PreTR (43.0 ± 10.8 cm/s; P < 0.05). PreTR, the reduction in PCAv observed from rest to exercise (5.2 ± 1.8%) was mitigated PostTR (P < 0.001). Similarly, exercise training enhanced ICA flow during submaximal exercise (~8.6 ± 13.7%), resulting in increased ICA flow PostTR compared with a reduced flow PreTR (P < 0.001). Although both end-tidal partial pressure of carbon dioxide and mean arterial pressure responses during incremental exercise were greater PostTR than PreTR, only the improved PETCO2 was related to the improved ICA flow (R² = 0.14; P < 0.05). Our findings suggest that short-term exercise training improves cerebrovascular function during exercise in patients with LVADs. This finding should encourage future studies investigating long-term exercise training and cerebral and peripheral vascular adaptation.NEW & NOTEWORTHY Left ventricular assist devices, now used as destination therapy in end-stage heart failure, enable patients to undertake rehabilitative exercise training. We show, for the first time in humans, that training improves cerebrovascular function during exercise in patients with left ventricular assist devices. This finding may have implications for cerebrovascular health in patients with heart failure.

The Effects of Water-based Exercise Training in People with Type 2 Diabetes

PURPOSE

To investigate the effects of 8 wk of upright water-based exercise training in people with type 2 diabetes.

METHODS

Thirteen participants with type 2 diabetes (54% male; 60.9 ± 9.6 yr, mean ± standard deviation) completed 8 wk of upright water-based exercise training at a moderate intensity (60%-80% of exercise test-derived maximum HR), for 1 h, three times a week (TG). Fourteen participants (64% male; 63.9 ± 9.8 yr) acted as a control group (CG) who maintained their usual activities. Preintervention and postintervention, participants performed cardiopulmonary exercise testing to determine V˙O2peak and one-repetition maximum testing to assess muscular strength. Blood profiles were assessed with standard assays. Body mass index and waist/hip ratio were employed as measures of anthropometry. Endothelium-dependent (brachial artery flow-mediated dilation) and independent (glyceryl trinitrate-mediated) function were assessed using vascular ultrasound.

RESULTS

Water-based training increased V˙O2peak (18.5 ± 4.3 mL·kg·min to 21.5 ± 5.4 mL·kg·min) (P = 0.002), overall muscle strength (123 ± 44 kg to 139 ± 43 kg) and leg strength (92 ± 28 kg to 104 ± 29 kg), compared with the CG (P = 0.001). The effect on pectoral strength (31 ± 17 kg to 35 ± 16 kg) was not significantly different to the CG (24 ± 12 kg to 26 ± 14 kg) (P = 0.08). No change was observed in anthropometry, blood profiles, or glyceryl trinitrate-mediated vascular function. Flow-mediated dilation was increased after training (6.1% ± 2.4% to 6.5% ± 3.0%), compared with controls who demonstrated a slight decrease (6.2% ± 1.6% to 5.4% ± 1.6%) (P = 0.002).

CONCLUSIONS

Water-based circuit training was well tolerated and appears to be an effective exercise modality for improving aerobic fitness, strength, and vascular function in people with type 2 diabetes.

Single-leg cycling increases limb-specific blood flow without concurrent increases in normalised power output when compared with double-leg cycling in healthy middle-aged adults

This study examined the acute performance, cardiovascular and local muscular responses to perceived exertion-based high-intensity interval exercise using either double- or single-leg cycling. Fifteen healthy middle-aged adults completed, on separate occasions, ten 30-s double-leg intervals interspersed with 60 s passive recovery and twenty (ten with each leg) 30-s single-leg intervals interspersed with 60 s passive recovery. Impedance cardiography, blood pressure, muscle oxygenation and total haemoglobin content (near-infrared spectroscopy), oxygen consumption and power output were measured throughout each session. Normalised to the lean mass used during each trial, single-leg cycling resulted in lower power output (single-leg: 8.92 ± 1.74 W kg^-1 and double-leg: 10.41 ± 3.22 W kg^-1; p < 0.05) but greater oxygen consumption (single-leg: 103 ± 11 mL kg^-1 min^-1 and double-leg: 84 ± 21 mL kg^-1 min^-1; p < 0.01) and cardiac output (single-leg: 1407 ± 334 mL kg^-1 min^-1 and double-leg: 850 ± 222 mL kg^-1 min^-1; p < 0.01), compared with double-leg cycling. Mean arterial pressure (double-leg: 108 ± 11 mmHg and single-leg: 102 ± 10 mmHg), change in total haemoglobin content (double-leg: 8.76 ± 10.65 µM cm s^-1 and single-leg: 13.42 ± 4.10 µM cm s^-1) and change in tissue oxygenation index (double-leg: -4.51 ± 3.56% and single-leg: -3.97 ± 3.91%) were not different between double-leg and single-leg cycling. When compared to double-leg cycling, single-leg cycling elicited a higher cardiac output relative to the lean mass, but this did not result in greater power output. The dissociation between blood availability and power output is consistent with an ageing model characterised by a decrease in local oxygen delivery and distribution capability.

Exercise Professionals with Advanced Clinical Training Should be Afforded Greater Responsibility in Pre-Participation Exercise Screening: A New Collaborative Model between Exercise Professionals and Physicians

Regular exercise improves health but can also induce adverse responses. Although such episodes are rare, many guidelines for pre-participation exercise screening have historically had a low threshold for recommending medical clearance prior to the commencement of exercise, placing the responsibility for decision making about exercise participation on physicians. The ‘clearance to exercise’ model still occurs widely in practice, but creates cost burdens and barriers to the uptake of exercise. Moreover, many physicians are not provided the training, nor time in a standard consultation, to be able to effectively perform this role. We present a model for pre-participation exercise screening and the initial assessment of clients wishing to commence an exercise programme. It is designed to guide professional practice for the referral, assessment and prescription of exercise for people across the health spectrum, from individuals who are apparently healthy, through to clients with pre-existing or occult chronic conditions. The model removes the request that physicians provide a ‘clearance’ for patients to engage in exercise programmes. Instead the role of physicians is identified as providing relevant clinical guidance to suitably qualified exercise professionals to allow them to use their knowledge, skills and expertise in exercise prescription to assess and manage any risks related to the prescription and delivery of appropriate exercise programmes. It is anticipated that removing unjustified barriers to exercise participation, such as mandated medical review, will improve the uptake of exercise by the unacceptably high proportion of the population who do not undertake sufficient physical activity for health benefit.

Improvements in fitness are not obligatory for exercise training-induced improvements in CV risk factors

The purpose of this study was to assess whether changes in physical fitness relate to changes in cardiovascular risk factors following standardized, center-based and supervised exercise training programs in subjects with increased cardiovascular risk. We pooled data from exercise training studies of subjects with increased cardiovascular risk (n = 166) who underwent 8-52 weeks endurance training. We determined fitness (i.e., peak oxygen uptake) and traditional cardiovascular risk factors (body mass index, blood pressure, total cholesterol, high-density lipoprotein cholesterol), before and after training. We divided subjects into quartiles based on improvement in fitness, and examined whether these groups differed in terms of risk factors. Associations between changes in fitness and in cardiovascular risk factors were further tested using Pearson correlations. Significant heterogeneity was apparent in the improvement of fitness and individual risk factors, with nonresponder rates of 17% for fitness, 44% for body mass index, 33% for mean arterial pressure, 49% for total cholesterol, and 49% for high-density lipoprotein cholesterol. Neither the number, nor the magnitude, of change in cardiovascular risk factors differed significantly between quartiles of fitness change. Changes in fitness were not correlated with changes in cardiovascular risk factors (all P > 0.05). Our data suggest that significant heterogeneity exists in changes in peak oxygen uptake after training, while improvement in fitness did not relate to improvement in cardiovascular risk factors. In subjects with increased cardiovascular risk, improvements in fitness are not obligatory for training-induced improvements in cardiovascular risk factors.

Active and Inactive Leg Hemodynamics during Sequential Single-Leg Interval Cycling

INTRODUCTION

Leg order during sequential single-leg cycling (i.e., exercising both legs independently within a single session) may affect local muscular responses potentially influencing adaptations. This study examined the cardiovascular and skeletal muscle hemodynamic responses during double-leg and sequential single-leg cycling.

METHODS

Ten young healthy adults (28 ± 6 yr) completed six 1-min double-leg intervals interspersed with 1 min of passive recovery and, on a separate occasion, 12 (six with one leg followed by six with the other leg) 1-min single-leg intervals interspersed with 1 min of passive recovery. Oxygen consumption, heart rate, blood pressure, muscle oxygenation, muscle blood volume, and power output were measured throughout each session.

RESULTS

Oxygen consumption, heart rate, and power output were not different between sets of single-leg intervals, but the average of both sets was lower than the double-leg intervals. Mean arterial pressure was higher during double-leg compared with sequential single-leg intervals (115 ± 9 vs 104 ± 9 mm Hg, P < 0.05) and higher during the initial compared with second set of single-leg intervals (108 ± 10 vs 101 ± 10 mm Hg, P < 0.05). The increase in muscle blood volume from baseline was similar between the active single leg and the double leg (267 ± 150 vs 214 ± 169 μM·cm, P = 0.26). The pattern of change in muscle blood volume from the initial to second set of intervals was significantly different (P < 0.05) when the leg was active in the initial (-52.3% ± 111.6%) compared with second set (65.1% ± 152.9%).

CONCLUSIONS

These data indicate that the order in which each leg performs sequential single-leg cycling influences the local hemodynamic responses, with the inactive muscle influencing the stimulus experienced by the contralateral leg.

Muscle size explains low passive skeletal muscle force in heart failure patients

Background

Alterations in skeletal muscle function and architecture have been linked to the compromised exercise capacity characterizing chronic heart failure (CHF). However, how passive skeletal muscle force is affected in CHF is not clear. Understanding passive force characteristics in CHF can help further elucidate the extent to which altered contractile properties and/or architecture might affect muscle and locomotor function. Therefore, the aim of this study was to investigate passive force in a single muscle for which non-invasive measures of muscle size and estimates of fiber force are possible, the soleus (SOL), both in CHF patients and age- and physical activity-matched control participants.

Methods

Passive SOL muscle force and size were obtained by means of a novel approach combining experimental data (dynamometry, electromyography, ultrasound imaging) with a musculoskeletal model.

Results

We found reduced passive SOL forces (∼30%) (at the same relative levels of muscle stretch) in CHF vs. healthy individuals. This difference was eliminated when force was normalized by physiological cross sectional area, indicating that reduced force output may be most strongly associated with muscle size. Nevertheless, passive force was significantly higher in CHF at a given absolute muscle length (non length-normalized) and likely explained by the shorter muscle slack lengths and optimal muscle lengths measured in CHF compared to the control participants. This later factor may lead to altered performance of the SOL in functional tasks such gait.

Discussion

These findings suggest introducing exercise rehabilitation targeting muscle hypertrophy and, specifically for the calf muscles, exercise that promotes muscle lengthening.

What Doesn't Kill You Makes You Fitter: A Systematic Review of High-Intensity Interval Exercise for Patients with Cardiovascular and Metabolic Diseases

High-intensity interval exercise (HIIE) has gained popularity in recent years for patients with cardiovascular and metabolic diseases. Despite potential benefits, concerns remain about the safety of the acute response (during and/or within 24 hours postexercise) to a single session of HIIE for these cohorts. Therefore, the aim of this study was to perform a systematic review to evaluate the safety of acute HIIE for people with cardiometabolic diseases. Electronic databases were searched for studies published prior to January 2015, which reported the acute responses of patients with cardiometabolic diseases to HIIE (≥80% peak power output or ≥85% peak aerobic power, VO2peak). Eleven studies met the inclusion criteria (n = 156; clinically stable, aged 27-66 years), with 13 adverse responses reported (~8% of individuals). The rate of adverse responses is somewhat higher compared to the previously reported risk during moderate-intensity exercise. Caution must be taken when prescribing HIIE to patients with cardiometabolic disease. Patients who wish to perform HIIE should be clinically stable, have had recent exposure to at least regular moderate-intensity exercise, and have appropriate supervision and monitoring during and after the exercise session.

Gait analysis in chronic heart failure: The calf as a locus of impaired walking capacity

Reduced walking capacity, a hallmark of chronic heart failure (CHF), is strongly correlated with hospitalization and morbidity. The aim of this work was to perform a detailed biomechanical gait analysis to better identify mechanisms underlying reduced walking capacity in CHF. Inverse dynamic analyses were conducted in CHF patients and age- and exercise level-matched control subjects on an instrumented treadmill at self-selected treadmill walking speeds and at speeds representing +20% and -20% of the subjects' preferred speed. Surprisingly, no difference in preferred speed was observed between groups, possibly explained by an optimization of the mechanical cost of transport in both groups (the mechanical cost to travel a given distance; J/kg/m). The majority of limb kinematics and kinetics were also similar between groups, with the exception of greater ankle dorsiflexion angles during stance in CHF. Nevertheless, over two times greater ankle plantarflexion work during stance and per distance traveled is required for a given triceps surae muscle volume in CHF patients. This, together with a greater reliance on the ankle compared to the hip to power walking in CHF patients, especially at faster speeds, may contribute to the earlier onset of fatigue in CHF patients. This observation also helps explain the high correlation between triceps surae muscle volume and exercise capacity that has previously been reported in CHF. Considering the key role played by the plantarflexors in powering walking and their association with exercise capacity, our findings strongly suggest that exercise-based rehabilitation in CHF should not omit the ankle muscle group.

Exercise training and artery function in humans: nonresponse and its relationship to cardiovascular risk factors

The objectives of our study were to examine 1) the proportion of responders and nonresponders to exercise training in terms of vascular function; 2) a priori factors related to exercise training-induced changes in conduit artery function, and 3) the contribution of traditional cardiovascular risk factors to exercise-induced changes in artery function. We pooled data from our laboratories involving 182 subjects who underwent supervised, large-muscle group, endurance-type exercise training interventions with pre-/posttraining measures of flow-mediated dilation (FMD%) to assess artery function. All studies adopted an identical FMD protocol (5-min ischemia, distal cuff inflation), contemporary echo-Doppler methodology, and observer-independent automated analysis. Linear regression analysis was used to identify factors contributing to changes in FMD%. We found that cardiopulmonary fitness improved, and weight, body mass index (BMI), cholesterol, and mean arterial pressure (MAP) decreased after training, while FMD% increased in 76% of subjects (P < 0.001). Training-induced increase in FMD% was predicted by lower body weight (β = -0.212), lower baseline FMD% (β = -0.469), lower training frequency (β = -0.256), and longer training duration (β = 0.367) (combined: P < 0.001, r = 0.63). With the exception of a modest correlation with total cholesterol (r = -0.243, P < 0.01), changes in traditional cardiovascular risk factors were not significantly related to changes in FMD% (P > 0.05). In conclusion, we found that, while some subjects do not demonstrate increases following exercise training, improvement in FMD% is present in those with lower pretraining body weight and endothelial function. Moreover, exercise training-induced change in FMD% did not correlate with changes in traditional cardiovascular risk factors, indicating that some cardioprotective effects of exercise training are independent of improvement in risk factors.

Soleus fascicle length changes are conserved between young and old adults at their preferred walking speed

Older adults have been shown to naturally select a walking speed approximately 20% slower than younger adults. We explored the possibility that a reduction in preferred speed in older adults represents a strategy to preserve the mechanical function of the leg muscles. We examined this question in the soleus muscle in eight healthy young (25.8±3.5 years) and eight healthy older adults (66.1±2.3 years) who were paired so that their preferred speed differed by ∼20%. Soleus muscle fascicle lengths were recorded dynamically using ultrasound, together with simultaneous measurements of soleus EMG activity and ankle joint kinematics while (a) older adults walked on a treadmill at a speed 20% above their preferred speed (speeds matched to the preferred speed of young adults), and (b) young and older adults walked at their preferred treadmill speeds. Analyses of mean muscle fascicle length changes revealed that, at matched speeds, older adults had a statistically different soleus fascicle length pattern compared to young adults, where the muscle's stretch-shorten cycle during stance was diminished. However, older adults walking at their preferred speed exhibited a more pronounced stretch-shorten cycle that was not statistically different from young adults. Conserving muscle length patterns through a reduction in speed in older adults may represent a physiologically relevant modulation of muscle function that permits greater force and power production. Our findings offer a novel mechanical explanation for the slower walking speed in older adults, whereby a reduction in speed may permit muscles to function in a mechanically similar manner to that of younger adults.

Build it and they will come: outcomes from a successful cardiac rehabilitation program at an Aboriginal Medical Service

Objective. Cardiovascular disease (CVD) is the leading disease burden in Aboriginal Australians, but culturally appropriate cardiac rehabilitation programs are lacking. We evaluated the uptake and effects on lifestyle, and cardiovascular risk factors, of cardiac rehabilitation at an Aboriginal Medical Service (AMS). Methods. The program involved weekly exercise and education sessions (through ‘yarning’) for Aboriginal people with or at risk of CVD. Participants’ perceptions of the program and the impact on risk factors were evaluated following 8 weeks of attendance. Results. In twenty-eight participants (20 females) who completed 8 weeks of sessions, body mass index (34.0 ± 5.1 v. 33.3 ± 5.2 kg m–2; P < 0.05), waist girth (113 ± 14 v. 109 ± 13 cm; P < 0.01) and blood pressure (135/78 ± 20/12 v. 120/72 ± 16/5 mmHg; P < 0.05) decreased and 6- min walk distance increased (296 ± 115 v. 345 ± 135 m; P < 0.01). ‘Yarning’ helped identify and address a range of chronic health issues including medication compliance, risk factor review and chest pain management. Conclusions. AMS-based cardiac rehabilitation was well attended, and improved cardiovascular risk factors and health management. An AMS is an ideal location for managing cardiovascular health and provides a setting conducive to addressing a broad range of chronic conditions. What is known about the topic? Cardiovascular disease is the leading cause of morbidity and mortality in Aboriginal Australians, but less than 5% of eligible Aboriginal people attend hospital-based cardiac rehabilitation. What does this paper add? This is the first study to describe a culturally appropriate cardiac rehabilitation program conducted in a metropolitan Aboriginal Medical Service. It provides a detailed account of the program’s components and its effects on physical and psychosocial determinants of cardiovascular health in participants. What are the implications for practitioners? Health management programs similar to the one evaluated in this study could be developed to suit the specific needs of other Indigenous communities around Australia to address a range of chronic conditions.

A comparison of the acute haemodynamic response to aerobic and resistance exercise in subjects with exercise-induced pulmonary arterial hypertension

BACKGROUND

Exercise-induced pulmonary arterial hypertension (EIPAH) is associated with reduced exercise capacity and abnormal central haemodynamic responses to maximal aerobic exercise. Aerobic and resistance exercise training are commonly employed to treat reduced exercise capacity; however, the haemodynamic response to aerobic and resistance exercise, at training intensities, in subjects with EIPAH is unknown.

METHODS

Fourteen subjects (11 with scleroderma, 12 females) with EIPAH underwent cardiopulmonary exercise testing on a cycle ergometer, a one-repetition maximum (1RM) strength test and resistance exercise at 40% and 60% of maximum on a bilateral leg press machine. All tests were performed with a pulmonary artery catheter in situ. Haemodynamic and symptomatic responses to aerobic and resistance exercise, performed at 40% of peak oxygen consumption and 40% of 1RM, and at 60% of peak oxygen consumption and 60% of 1RM, were compared. For maximal exercise, the highest haemodynamic responses recorded during the cycling and 1RM tests were compared.

RESULTS

There were no differences in haemodynamic or symptomatic responses between the two modalities of submaximal exercise. At maximal exercise, all haemodynamic and symptomatic responses were lower during resistance compared with aerobic exercise (p < 0.05).

CONCLUSIONS

At the intensities studied, lower-limb resistance exercise was well tolerated and was mostly associated with similar or lower haemodynamic responses compared with aerobic exercise, in subjects with EIPAH.

The Impact of Exercise Training on Conduit Artery Wall Thickness and Remodeling in Chronic Heart Failure Patients

Exercise training is an important adjunct to medical therapy in chronic heart failure, but the extent to which exercise impacts on conduit artery remodeling is unknown. The aim of this study was to evaluate the impact of aerobic and resistance exercise training modalities on arterial remodeling in patients with chronic heart failure. We randomized 36 untrained subjects with chronic heart failure to resistance training (58.8±3.5 years), aerobic training (61.3±2.8 years), or an untrained control group (64.4±2.4 years). Peak oxygen consumption during cycle ergometry increased after 12 weeks in both the resistance and aerobic training ( P <0.001) groups, but not in controls, whereas leg strength only increased after resistance training ( P <0.05). Brachial artery wall thickness decreased in the resistance training group (475±10 versus 443±13 μm; P <0.01), whereas no changes were apparent in the aerobic or control groups. Brachial diameter increased by ≈6% and ≈5% in the aerobic training and resistance training groups ( P <0.01), with no change evident in the control group. The wall:lumen ratio consequently declined in the resistance training group at 12 weeks (0.121±0.004 versus 0.107±0.004; P <0.01) and increased in the control group (0.111±0.006 versus 0.121±0.009; P <0.05). No wall:lumen change was evident in the aerobic training group. Our findings suggest that exercise has a systemic impact on remodeling of conduit arteries in humans and that resistance exercise training may be advantageous in subjects with chronic heart failure in this regard.

Impact of inactivity and exercise on the vasculature in humans

The effects of inactivity and exercise training on established and novel cardiovascular risk factors are relatively modest and do not account for the impact of inactivity and exercise on vascular risk. We examine evidence that inactivity and exercise have direct effects on both vasculature function and structure in humans. Physical deconditioning is associated with enhanced vasoconstrictor tone and has profound and rapid effects on arterial remodelling in both large and smaller arteries. Evidence for an effect of deconditioning on vasodilator function is less consistent. Studies of the impact of exercise training suggest that both functional and structural remodelling adaptations occur and that the magnitude and time-course of these changes depends upon training duration and intensity and the vessel beds involved. Inactivity and exercise have direct "vascular deconditioning and conditioning" effects which likely modify cardiovascular risk.

Relationship between changes in brachial artery flow-mediated dilation and basal release of nitric oxide in subjects with Type 2 diabetes

Assessment of flow-mediated dilation (FMD) after forearm ischemia is widely used as a noninvasive bioassay of stimulated nitric oxide (NO)-mediated conduit artery vasodilator function in vivo. Whether this stimulated endothelial NO function reflects basal endothelial NO function is unknown. To test this hypothesis, retrospective analysis of randomized crossover studies was undertaken in 17 subjects with Type 2 diabetes; 9 subjects undertook an exercise training or control period, whereas the remaining 8 subjects were administered an angiotensin II receptor blocker or placebo. FMD was assessed by using wall tracking of high-resolution brachial artery ultrasound images in response to reactive hyperemia. Resistance vessel basal endothelium-dependent NO function was assessed by using intrabrachial administration of NG-monomethyl-l-arginine (l-NMMA) and plethysmographic assessment of forearm blood flow (FBF). FMD was higher after intervention compared with control/placebo (6.15 ± 0.53 vs. 3.81 ± 0.72%, P < 0.001). There were no significant changes in the FBF responses to l-NMMA. Regression analysis between FMD and l-NMMA responses at entry to the study revealed an insignificant correlation ( r = −0.10, P = 0.7), and improvements in FMD with the interventions were not associated with changes in the l-NMMA responses ( r = −0.04, P = 0.9). We conclude that conduit artery-stimulated endothelial NO function (FMD) does not reflect basal resistance vessel endothelial NO function in subjects with Type 2 diabetes.

Impaired skin blood flow response to environmental heating in chronic heart failure

AIMS

We examined the thermoregulatory response to heat exposure in patients with chronic heart failure.

METHODS AND RESULTS

Skin blood flow (SkBF) was measured in HF subjects and matched controls. Cutaneous vascular conductance (CVC) was calculated from laser-Doppler SkBF and blood pressure. To assess the nitric oxide contribution to thermoregulatory responses, subcutaneous microdialysis membranes were placed beneath the laser-Doppler probes to infuse N(G)-nitro-l-arginine methyl ester (l-NAME), or Ringer's solution. Core (T(C)) and skin temperatures (five sites, T(Sk)) were continuously recorded. Subjects were studied during normothermia then at 38 degrees C, 50%RH within a climate chamber. T(C) and T(Sk) did not differ between HF and controls during normothermia and heating induced similar increases in both groups. During heating, CVC rose in both groups, but significantly less so in HF (HF 43.9+/-7.8 vs. controls 58.0+/-7.5% CVC(max), P<0.05). l-NAME attenuated SkBF responses in the control (58.0+/-7.5 vs. 34.6+/-5.1% CVC(max), P<0.001) and HF subjects (43.9+/-7.8 vs. 27.0+/-2.2% CVC(max), P<0.005), with a larger effect evident in the controls (P<0.05).

CONCLUSION

HF patients exhibit impaired thermoregulatory responses to heat exposure. Lower SkBF in HF, which defends blood pressure during heat exposure, also predisposes these subjects to heat intolerance.

A comparison of ambulatory oxygen consumption during circuit training and aerobic exercise in patients with chronic heart failure

PURPOSE

This study compared the exercise intensity of a combined aerobic and resistance exercise circuit training session with the exercise intensity of continuous aerobic exercise in patients with chronic heart failure (CHF).

METHODS

Peak oxygen consumption (VO2peak) and muscular strength (1 repetition maximum) were assessed in six CHF patients (age 62 +/- 3 years). Heart rate, rate of perceived exertion (RPE), blood pressures, ambulatory oxygen consumption (VO2), and ventilatory data were measured during two types of exercise: continuous cycling on a bicycle ergometer (aerobic [AER] session) and combined AER and resistance exercise (circuit training [CIR] session).

RESULTS

There were no significant differences in VO2, RPE, heart rate, or hemodynamic responses (rate pressure product, diastolic blood pressure, or mean arterial pressure) during exercise, between the two sessions. Systolic blood pressure was significantly lower during CIR (P < 0.05). Minute ventilation and tidal volume were significantly higher (P < 0.0001 and P < 0.01, respectively) and respiratory frequency significantly lower (P < 0.005) during CIR. During CIR, RPE significantly correlated with VO2 (P < 0.01), whereas heart rate did not. Conversely, during the AER session HR correlated with VO2 (P < 0.01), but RPE did not.

CONCLUSIONS

Circuit training is a well-tolerated form of exercise training for CHF patients that is associated with similar oxygen and hemodynamic demand to aerobic exercise. Results suggest that RPE may be a better method of prescribing and monitoring exercise intensity during CIR, with heart rate the preferred measure of intensity during aerobic exercise.

Beneficial effect of vitamin E administration on nitric oxide function in subjects with hypercholesterolaemia

1. Vitamin E administration improves endothelial function in hypercholesterolaemic animals but, generally, has not been found to do so in man. The aim of this study was to determine whether vitamin E administration improves basal or stimulated function of the nitric oxide (NO) dilator system in patients with hypercholesterolaemia. 2. Seven subjects aged 47+/-3 (+/-S.E.M.) years with moderately elevated serum cholesterol concentrations (6.0+/-0.1 mmol/l) were given 4 weeks of placebo therapy followed by 500 i.u. of vitamin E twice daily for 4 weeks. Endothelium-dependent and -independent vasodilatation were assessed by intrabrachial infusion of acetylcholine and sodium nitroprusside, and forearm blood flow was measured by strain-gauge plethysmography. Basal NO function was assessed by infusion of NG-monomethyl-L-arginine. 3. Plasma alpha-tocopherol concentration was enhanced after administration of vitamin E (34.6+/-1.8 to 86.9+/-9.6 micromol/l; P<0.001). In addition, vitamin E administration significantly increased acetylcholine-mediated vasodilatation whether the results were expressed in terms of changes in absolute forearm blood flow (P<0. 01), forearm vascular resistance (P<0.05) or forearm blood flow ratios (P<0.001). Similarly, absolute forearm blood flow (P<0.05), forearm vascular resistance (P<0.01) and forearm blood flow ratio (P<0.01) responses to NG-monomethyl-L-arginine were augmented by vitamin E therapy. Sodium nitroprusside responses were unaltered. 4. These results indicate that 4 weeks therapy with 1000 i.u. of vitamin E daily improves basal and stimulated NO-related endothelial function in subjects with hypercholesterolaemia.

A controlled trial of circuit weight training on aerobic capacity and myocardial oxygen demand in men after coronary artery bypass surgery

BACKGROUND

Cardiovascular benefits of resistance training in cardiac patients have been suggested but not studied in a randomized, controlled trial of circuit weight training (CWT) without an aerobic exercise component. The purpose of the current study was to examine the effects of 10 weeks of CWT on muscular strength, peak oxygen consumption (peak VO2), and myocardial oxygen demand (mVO2) in men after coronary artery bypass surgery.

METHODS

Twenty-six, post-coronary bypass male subjects (mean 19 months after bypass), aged 60 +/- 8.5 years, were randomly allocated to 10 weeks of CWT at 40 to 60% of maximum voluntary contraction (n = 12) or to a control group (n = 14). Muscular strength was assessed using a modified one repetition maximum technique. Peak VO2 was recorded during symptom-limited treadmill exercise. Rate pressure product, as an indirect measure of mVO2, was measured during isometric, isodynamic, and dynamic exercise.

RESULTS

No ischemic symptoms nor electrocardiographic changes were recorded during testing or training. Strength increased by 18% (P < 0.005) in five out of seven exercises in the training group, but was unchanged in the control group. Training did not improve peak VO2. Rate pressure product during isometric and isodynamic exercise decreased from pre- to post-testing (P < 0.05) but was equivalent to that seen in the control group.

CONCLUSIONS

Moderate intensity CWT is safe and can improve strength in selected low-risk patients after coronary artery bypass surgery. However, it does not significantly increase peak VO2 nor reduce mVO2 during isometric, isodynamic, and dynamic exercise.