Acute responses to resistance training and safety

German volume training for health promotion: Acute vasopressor, pulmonary and metabolic responses

Resistance training (RT) is increasingly recommended for incorporation into comprehensive fitness or "exercise as medicine" programs. However, the acute effects of RT, and especially its different sub-types, and how they impact health outcomes are not fully investigated. This study evaluated German Volume Training (GVT) ("10 set × 10 rep scheme") for its efficacy for its use in health settings. This study utilized a randomized crossover design with subjects serving as their own controls to establish baseline values. Subjects were blinded to the study hypothesis. Subjects performed a single session of GVT or no exercise, in a randomised order separated by a 1-week washout period. Outcomes were assessed before and immediately post-exercise. GVT significantly (p < 0.05) decreased systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP), but increased heart rate (HR), rate pressure product (RPP) and rating of perceived exertion (RPE). No changes were found in the measured spirometry parameters. Increases were observed in carbon dioxide production (VCO₂) and minute ventilation (V_E), but not respiratory exchange ratio. Post hoc analysis demonstrated that post-GVT values were significantly lower for SBP (p = 0.017; d = 1.00), DBP (p = 0.013; d = 0.90), MAP (p = 0.024; d = 1.06), and VCO₂ (p = 0.009; d = -1.32), and significantly higher for RPP (p = 0.001; d = -3.11), RPE (p = 0.001; d = -14.14), and HR (p = 0.001; d = -3.00). This study indicates that acute GVT promotes post-exercise hypotension and is of sufficient intensity to increase both objective HR and subjective RPE intensities appropriately for use in a variety of health promotion settings.

Researchers' Perspectives on Adverse Event Reporting in Resistance Training Trials: A Qualitative Study

The objectives of our study were to understand researchers' current practices and perspectives on adverse event (AE) reporting in clinical trials of resistance training (RT), and identify barriers and facilitators of AE reporting. We conducted web conference or telephone-based one-on-one semi-structured interviews with 14 researchers who have published RT studies in individuals with or without health conditions. We audio-recorded and transcribed the interviews, and analyzed data using the thematic framework method. Four themes were identified in the context of RT studies: 1) researchers lack guidance and/or motivation for rigorous AE reporting; 2) researchers who undertake AE reporting educate and value participants, use trained personnel, and implement standardized guidelines; 3) suboptimal implementation of existing AE reporting standards and the perception that available guidelines do not apply to exercise trials; and 4) acceptability and feasibility of an exercise-specific guide for AE reporting depends on its content and format. In conclusion, AE reporting methods in the field of exercise science do not align with best practice. Strategies to reduce inconsistent and suboptimal AE reporting in RT trials are urgently needed and could be based on the barriers and facilitators identified in this study.

Immediate and cumulative effects of upper-body isometric exercise on the cornea and anterior segment of the human eye

Objectives

The execution of isometric resistance training has demonstrated to cause changes in the ocular physiology. The morphology of the cornea and anterior chamber is of paramount importance in the prevention and management of several ocular diseases, and thus, understating the impact of performing isometric exercise on the eye physiology may allow a better management of these ocular conditions. We aimed to determine the short-term effects of 2-minutes upper-body isometric effort at two different intensities on corneal and anterior eye morphology.

Methods

Eighteen healthy young adults performed a 2-minutes isometric biceps-curl exercise against two loads relative to their maximum strength capacity (high-intensity and low-intensity) in a randomized manner. An Oculus Pentacam was used to measure the corneal morphology and anterior chamber parameters in both experimental conditions at baseline, during the isometric effort (after 30, 60, 90 and 120 seconds), and after 30 and 120 seconds of passive recovery.

Results

We found that isometric effort causes an increase in pupil size (P < 0.001), and a decrease in the iridocorneal angle (P = 0.005), anterior chamber volume (P < 0.001) and K-flat (P < 0.001) during isometric effort, with these effects being more accentuated in high-intensity condition (P < 0.005 in all cases).Performing 2-minutes upper-body isometric effort did not alter anterior chamber depth, central corneal thickness, corneal volume, and K-steep (P > 0.05 in all cases).

Conclusions

Our data exhibit that performing 2-minutes of upper-body isometric exercise modifies several parameters of the corneal morphology and anterior eye biometrics, with these changes being greater for the high-intensity exercise condition. The findings of this study may be of relevance for the prevention and management of corneal ectasias and glaucoma.

The effect of breathing technique on sticking region during maximal bench press

The intrathoracic pressure and breathing strategy on bench press (BP) performance is highly discussed in strength competition practice. Therefore, the purpose of this study was to analyze whether different breathing techniques can influence the time and track characteristics of the sticking region (SR) during the 1RM BP exercise. 24 healthy, male adults (age 23 ± 2.4 yrs., body mass 85 ± 9.2 kg, height 181 ± 5.4 cm) performed a 1 repetition BP using the breathing technique of Valsalva maneuver (VM), hold breath, lung packing (PAC), and reverse breathing (REVB), while maximum lifted load and concentric phase kinematics were recorded. The results of ANOVA showed that the REVB breathing decreased absolute (p < 0.04) and relative lifted load (p < 0.01). The VM showed lower (p = 0.01) concentric time of the lift than the other breathing techniques. The VM and PAC showed lower SR time than other breathing techniques, where PAC showed a lower SR time than VM (p = 0.02). The PAC techniques resulted in shorter SR and pre-SR track than other breathing techniques and the REVB showed longer SR track than the other considered breathing techniques (p = 0.04). Thus, PAC or VM should be used for 1RM BP lifting according to preferences, experiences and lifting comfort of an athlete. The hold breath technique does not seem to excessively decrease the lifting load, but this method will increase the lifting time and the time spend in the sticking region, therefore its use does not provide any lifting benefit. The authors suggest that the REVB should not be used during 1 RM lifts.

Resistance Exercise in Prostate Cancer Patients: a Short Review

Purpose of Review

The aim of this paper is to provide an overview of recent findings concerning the utilization of resistance exercise (RE) in prostate cancer (PCa), in particular as pertaining to the management of cancer therapy side effects.

Recent Findings

As of late, studies investigating the effects of RE in PCa patients have found positive effects on muscle strength, body composition, physical functioning, quality of life, and fatigue. The combination of RE and impact training appears to decrease the loss of bone mineral density. RE seems to be well accepted and tolerated, even by patients with bone metastatic disease, although a modification of the RE prescription is often necessary.

Summary

In PCa patients, RE has been well-researched and the data are clear that it is beneficial in multiple ways. Future directions should look at the long-term effects of RE, including mortality and relapse, as well as implementation of exercise programs.

International Exercise Recommendations in Older Adults (ICFSR): Expert Consensus Guidelines

The human ageing process is universal, ubiquitous and inevitable. Every physiological function is being continuously diminished. There is a range between two distinct phenotypes of ageing, shaped by patterns of living - experiences and behaviours, and in particular by the presence or absence of physical activity (PA) and structured exercise (i.e., a sedentary lifestyle). Ageing and a sedentary lifestyle are associated with declines in muscle function and cardiorespiratory fitness, resulting in an impaired capacity to perform daily activities and maintain independent functioning. However, in the presence of adequate exercise/PA these changes in muscular and aerobic capacity with age are substantially attenuated. Additionally, both structured exercise and overall PA play important roles as preventive strategies for many chronic diseases, including cardiovascular disease, stroke, diabetes, osteoporosis, and obesity; improvement of mobility, mental health, and quality of life; and reduction in mortality, among other benefits. Notably, exercise intervention programmes improve the hallmarks of frailty (low body mass, strength, mobility, PA level, energy) and cognition, thus optimising functional capacity during ageing. In these pathological conditions exercise is used as a therapeutic agent and follows the precepts of identifying the cause of a disease and then using an agent in an evidence-based dose to eliminate or moderate the disease. Prescription of PA/structured exercise should therefore be based on the intended outcome (e.g., primary prevention, improvement in fitness or functional status or disease treatment), and individualised, adjusted and controlled like any other medical treatment. In addition, in line with other therapeutic agents, exercise shows a dose-response effect and can be individualised using different modalities, volumes and/or intensities as appropriate to the health state or medical condition. Importantly, exercise therapy is often directed at several physiological systems simultaneously, rather than targeted to a single outcome as is generally the case with pharmacological approaches to disease management. There are diseases for which exercise is an alternative to pharmacological treatment (such as depression), thus contributing to the goal of deprescribing of potentially inappropriate medications (PIMS). There are other conditions where no effective drug therapy is currently available (such as sarcopenia or dementia), where it may serve a primary role in prevention and treatment. Therefore, this consensus statement provides an evidence-based rationale for using exercise and PA for health promotion and disease prevention and treatment in older adults. Exercise prescription is discussed in terms of the specific modalities and doses that have been studied in randomised controlled trials for their effectiveness in attenuating physiological changes of ageing, disease prevention, and/or improvement of older adults with chronic disease and disability. Recommendations are proposed to bridge gaps in the current literature and to optimise the use of exercise/PA both as a preventative medicine and as a therapeutic agent.

The intraocular pressure response to lower-body and upper-body isometric exercises is affected by the breathing pattern

We assessed the mediating role of the breathing pattern adopted during isometric exercise on the intraocular pressure (IOP) response in the back squat and biceps curl exercises. Twenty physically active young adults performed sets of 1-minute isometric effort against a load corresponding to 80% of the maximum load while adopting three different breathing patterns: (i) Constant breathing: 10 cycles consisting of 3 s of inhalation and 3 s of exhalation, (ii) 10-sec Valsalva: 3 cycles consisting of 10 s holding the breath and 10 s of normal breathing, and (iii) 25-sec Valsalva: 2 cycles consisting of 25 s of the Valsalva maneuver and 5 s of normal breathing. A rebound tonometer was used to semi-continuously assesses IOP during the six sets of 1-minute isometric effort (2 exercises × 3 breathing patterns). We found a progressive IOP rise during isometric effort (P < 0.001, ηp2 = 0.83), with these increases being greater when the breath was held longer (P < 0.001, ηp2 = 0.58; 25-sec Valsalva > 10-sec Valsalva = constant breathing). There was a trend towards higher IOP values for the back squat in comparison to the biceps curl, although these differences did not reach statistical significance for any breathing pattern (corrected P-value ≥ 0.146, d ≤ 0.69). These findings reveal that glaucoma patients or those at risk should avoid activities in which the breath is held, especially when combined with physical exercise modalities that also promote an increment in IOP values (e.g. isometric contractions).

Are Blood Pressure and Cardiovascular Stress Greater in Isometric or in Dynamic Resistance Exercise?

Medical and sports medicine associations are reluctant to endorse isometric exercise to the same extent as dynamic resistance exercise (RE). The major concern is the fear of greater increases in blood pressure (BP) that might be associated with isometric exercise. This review comprehensively presents all human studies that directly compared the magnitude of hemodynamic responses between isometric and dynamic RE. We also discuss possible mechanisms controlling BP-response and cardiovascular adjustments during both types of RE. The most prominent finding was that isometric and dynamic RE using small-muscle mass evoke equal increases in BP; however, the circulatory adjustments contributing to this response are different in dynamic and isometric RE. In contrast, studies using large-muscle mass report inconsistent results for the magnitude of BP-response between the two types of RE. Thus, when the same muscles and workloads are used, the increase in BP during isometric and dynamic RE is more comparable to what is commonly believed. However, it should be noted that only a few studies equalized the workload in two types of RE, most used small sample sizes, and all studies employed healthy participants. More studies are needed to compare the cardiovascular risks associated with isometric and dynamic RE, especially in individuals with chronic disease.

Resistance Training for Older Adults: Position Statement From the National Strength and Conditioning Association

Fragala, MS, Cadore, EL, Dorgo, S, Izquierdo, M, Kraemer, WJ, Peterson, MD, and Ryan, ED. Resistance training for older adults: position statement from the national strength and conditioning association. J Strength Cond Res 33(8): 2019-2052, 2019-Aging, even in the absence of chronic disease, is associated with a variety of biological changes that can contribute to decreases in skeletal muscle mass, strength, and function. Such losses decrease physiologic resilience and increase vulnerability to catastrophic events. As such, strategies for both prevention and treatment are necessary for the health and well-being of older adults. The purpose of this Position Statement is to provide an overview of the current and relevant literature and provide evidence-based recommendations for resistance training for older adults. As presented in this Position Statement, current research has demonstrated that countering muscle disuse through resistance training is a powerful intervention to combat the loss of muscle strength and muscle mass, physiological vulnerability, and their debilitating consequences on physical functioning, mobility, independence, chronic disease management, psychological well-being, quality of life, and healthy life expectancy. This Position Statement provides evidence to support recommendations for successful resistance training in older adults related to 4 parts: (a) program design variables, (b) physiological adaptations, (c) functional benefits, and (d) considerations for frailty, sarcopenia, and other chronic conditions. The goal of this Position Statement is to a) help foster a more unified and holistic approach to resistance training for older adults, b) promote the health and functional benefits of resistance training for older adults, and c) prevent or minimize fears and other barriers to implementation of resistance training programs for older adults.

Systematic review of intra-abdominal and intrathoracic pressures initiated by the Valsalva manoeuvre during high-intensity resistance exercises

The Valsalva manoeuvre, intra-abdominal pressure (IAP) and intrathoracic pressure (ITP) play important roles in resistance training and common daily activities. The purpose of this review is to summarize the ITP and IAP responses to resistance exercises and to determine which exercises elicit the highest or lowest body pressure values under high-intensity resistance exercise. The PubMed, Scopus and Web of Science databases were searched until November 1, 2018. A combination of the following search terms was used: Valsalva manoeuvre, hold breath, controlled breathing, controlled breath, abdominal pressure, intrathoracic pressure AND weight training, resistance exercise, power lifting. The search process yielded 1125 studies, of which 16 were accepted according to the selection criteria and methodological quality. The highest IAP was recorded during squats (over 200 mmHg) followed by deadlift, slide row and leg press (161–176 mmHg), and the lowest IAP was found during bench press (79±44 mmHg). The highest ITP was elicited by the leg press, deadlift and box lift (105–130 mmHg), which were higher than during the bench press (95±37 mmHg) and slide row (88±32 mmHg). We recommend the bench press and slide row as exercises useful for beginners and individuals with hypertension. Untrained individuals should not use heavy squats, deadlift, box lift and clean exercises until they have undergone progressive adaptation for lifting high loads resulting in high IAP and ITP. The values of IAP and ITP during high-intensity exercise seem to be determined mutually by the position of the human body and the external load.

Exercise Training as a Mediator for Enhancing Coronary Collateral Circulation: A Review of the Evidence

Coronary collateral vessels supply blood to areas of myocardium at risk after arterial occlusion. Flow through these channels is driven by a pressure gradient between the donor and the occluded artery. Concomitant with increased collateral flow is an increase in shear force, a potent stimulus for collateral development (arteriogenesis). Arteriogenesis is self-limiting, often ceasing prematurely when the pressure gradient is reduced by the expanding lumen of the collateral vessel. After the collateral has reached its self-limited maximal conductance, the only way to drive further increases is to re-establish the pressure gradient.

During exercise, the myocardial oxygen demand is increased, subsequently increasing coronary flow. Therefore, exercise may represent a means of driving augmented arteriogenesis in patients with stable coronary artery disease. Studies investigating the ability of exercise to drive collateral development in humans are inconsistent. However, these inconsistencies may be due to the heterogeneity of assessment methods used to quantify change. This article summarises current evidence pertaining to the role of exercise in the development of coronary collaterals, highlighting areas of future research.

Physiological responses in different intensities of resistance exercise - Critical load and the effects of aging process

Aim was to identify critical load (CL) in young and elderly apparently healthy male cohorts. To contrast the metabolic, cardiovascular and perceptual responses on CL according to age. We evaluated 12 young (23 ± 3 years) and 10 elderly (70 ± 2 years) apparently healthy active males, who underwent: (1) 1 repetition maximum (1RM) test on a 45° Leg Press; (2) on different days, three high-intensity resistance exercise constant load tests (60%, 75% and 90% 1RM) until fatigue (Tlim). Absolute values of both the CL asymptote and curvature constant (kg) were significantly lower in elderly subjects (P < 0.05). In contrast, elderly subjects demonstrated a significantly higher number of repetitions at CL when compared with young subjects (P < 0.05). As expected, oxygen uptake (VO₂) and heart rate (HR) during maximal aerobic exercise testing were significantly reduced in older subjects. However, percent-predicted aerobic capacity were higher in older subjects (P < 0.05). In addition, blood lactate ([La^-]) corrected to Tlim and rating of perceived exertion values were greater in younger subjects at all intensities (P < 0.05). These findings, despite reduced force production in older subjects, endurance-related parameters are well preserved according to age-adjusted percent-predicted values in apparently healthy males.

Blood pressure response between resistance exercise with and without blood flow restriction: A systematic review and meta-analysis

AIM

The aim of this study was to compare, by means of a systematic review and meta-analysis, the effects of resistance training with and without blood flow restriction (BFR) on blood pressure (BP).

MATERIALS AND METHODS

This review was composed according to the preferred Reporting items for Systematic Reviews and Meta-Analyses guidelines. Searches were carried out in the databases PubMed, SPORTDiscus, and Web of Science. BP was the main outcome for the analysis of the acute, post-exercise, and chronic effect of resistance exercise with and without BFR. Search results were limited to studies investigating the effect of resistance training with and without BFR on acute or chronic BP, published in a scientific peer-reviewed journal in English.

KEY FINDINGS

Seventeen references were eligible. During exercise, the diastolic BP (DBP) was higher in exercise with BFR (ES = 17.84) in comparison to traditional exercise with loads ≥60% 1RM (ES = 5.53; P < 0.01); and the systolic BP (SBP) and DBP were higher during exercise with BFR in hypertensive individuals (ES = 69.83 and 43.66) in comparison to traditional exercise with loads <60% 1RM (ES = 48.05 and 28.37; P < 0.05). In the post-exercise analysis, exercise with BFR presented lower values for SBP (ES = -5.13; P = 0.02) and DBP (ES = -4.70; P < 0.01).

SIGNIFICANCE

Although resistance exercise with BFR resulted in greater post-exercise hypotension than traditional exercise, higher SBP and/or DBP values were observed during exercise with BFR compared to traditional exercise, especially in hypertensive individuals. Thus, exercise with BFR should be prescribed with caution when BP control is necessary during exercise.

Acute Effects of Exercise Mode on Arterial Stiffness and Wave Reflection in Healthy Young Adults: A Systematic Review and Meta-Analysis

Background: This systematic review and meta-analysis quantified the effect of acute exercise mode on arterial stiffness and wave reflection measures including carotid-femoral pulse wave velocity (cf-PWV), augmentation index (AIx), and heart rate corrected AIx (AIx75). Methods: Using standardized terms, database searches from inception until 2017 identified 45 studies. Eligible studies included acute aerobic and/or resistance exercise in healthy adults, pre- and post-intervention measurements or change values, and described their study design. Data from included studies were analyzed and reported in accordance with the Cochrane Handbook for Systematic Reviews of Interventions and PRISMA guidelines. Meta-analytical data were reported via forest plots using absolute differences with 95% confidence intervals with the random effects model accounting for between-study heterogeneity. Reporting bias was assessed via funnel plots and, individual studies were evaluated for bias using the Cochrane Collaboration's tool for assessing risk of bias. A modified PEDro Scale was applied to appraise methodological concerns inherent to included studies. Results: Acute aerobic exercise failed to change cf-PWV (mean difference: 0.00 ms^-1 [95% confidence interval: -0.11, 0.11], p = 0.96), significantly reduced AIx (-4.54% [-7.05, -2.04], p = 0.0004) and significantly increased AIx75 (3.58% [0.56, 6.61], p = 0.02). Contrastingly, acute resistance exercise significantly increased cf-PWV (0.42 ms^-1 [0.17, 0.66], p = 0.0008), did not change AIx (1.63% [-3.83, 7.09], p = 0.56), and significantly increased AIx75 (15.02% [8.71, 21.33], p < 0.00001). Significant heterogeneity was evident within all comparisons except cf-PWV following resistance exercise, and several methodological concerns including low applicability of exercise protocols and lack of control intervention were identified. Conclusions: Distinct arterial stiffness and wave reflection responses were identified following acute exercise with overall increases in both cf-PWV and AIx75 following resistance exercise potentially arising fromcardiovascular and non-cardiovascular factors that likely differ from those following aerobic exercise. Future studies should address identified methodological limitations to enhance interpretation and applicability of arterial stiffness and wave reflection indices to exercise and health.

Recommendations for the prescription of physical exercise for patients with spondyloarthritis

OBJECTIVE

To develop expert-based recommendations on physical activity and exercise for patients with spondyloarthritis (SpA).

METHODS

Two discussion groups, one of physical therapists, rehabilitation physicians, and professionals of physical activity and sports, and another of rheumatologists interested in SpA, were held to discuss the results of a survey of rheumatologists on exercise and two focus groups with patients on barriers to exercise. Preliminary recommendations were drafted. These were submitted to the opinion of the experts in both groups according to a two round Delphi methodology.

RESULTS

Twenty one recommendations covering general aspects of exercise, adaptation to patient, how to deliver messages, pain management, and type of exercise and monitoring were issued. The level of agreement varied slightly between expert groups but it was high overall. Items with poor agreement were removed from the consensus.

CONCLUSIONS

We present recommendations on when and how to prescribe and monitor exercise in patients with SpA based on the opinion of experts in exercise and in SpA. We must now test whether these recommendations are useful for clinical practice and have an effect on patients with SpA seen by rheumatologists.

Reduced collagen accumulation and augmented MMP-2 activity in left ventricle of old rats submitted to high-intensity resistance training

Progressive fibrosis is a hallmark of the aging heart. Age-related fibrosis is modulated by endurance exercise training; however, little is known concerning the influence of resistance training (RT). Therefore we investigated the chronic effects of high-intensity RT on age-associated alterations of left ventricle (LV) structure, collagen content, matrix metalloproteinase-2 (MMP-2), and extracellular matrix-related gene expression, including transforming growth factor-β (TGF-β). Young adult (3 mo) and aged (21 mo) male Wistar rats were submitted to a RT protocol (ladder climbing with 65, 85, 95, and 100% load), three times a week for 12 wk. Forty-eight hours posttraining, arterial systolic and diastolic pressure, LV end-diastolic pressure (LVEDP) and dP/dt were recorded. LV morphology, collagen deposition, and gene expression of type I (COL-I) and type III (COL-III) collagen, MMP-2, tissue inhibitor of metalloproteinases-1 (TIMP-1), and TGF-β1 were analyzed by quantitative reverse transcriptase-PCR. MMP-2 content was assessed by zymography. Increased collagen deposition was observed in LV from aged rats. These parameters were modulated by RT and were associated with increased MMP-2 activity and decreased COL-I, TGF-β1, and TIMP-1 mRNA content. Despite the effect of RT on collagen accumulation, there was no improvement on LVEDP and maximal negative LV dP/dt of aged rats. Cardiomyocyte diameter was preserved in all experimental conditions. In conclusion, RT attenuated age-associated collagen accumulation, concomitant to the increase in MMP-2 activity and decreased expression of COL-I, TGF-β1, and TIMP-1 in LV, illustrating a cardioprotective effect of RT on ventricular structure and function.NEW & NOTEWORTHY We demonstrated the beneficial resistance-training effect against age-related left ventricle collagen accumulation in the left ventricle, which was associated with decreased type I collagen (COL-I), transforming growth factor-β1 (TGF-β1), and tissue inhibitor of metalloproteinases-1 (TIMP-1) gene expression and matrix metalloproteinase-2 (MMP-2) activity. Our findings suggest for the first time the potential effects of resistance training in modulating collagen accumulation and possibly fibrosis in the aging heart.

The Effect of Different Intensity Modalities of Resistance Training on Beat-to-Beat Blood Pressure in Cardiac Patients

Background

Resistance training has been introduced in cardiac rehabilitation to give more benefit than traditional training. Haemodynamic evaluation of cardiac patients to resistance training has generally consisted of continuous HR monitoring and discontinuous blood pressure measurements.

Design and Methods

Blood pressure (BP) and heart rate (HR) responses to resistance training were evaluated using continuous monitoring (Finapres) during low (four sets of 17 repetitions at 40% of the one-repetition maximum strength [1-RM]) and high intensity resistance training (four sets of 10 repetitions at 70% of 1-RM) on a leg extension machine in 14 patients who participated in a rehabilitation programme. Work volume was identical in the low- and high-level resistance training.

Results

The HR and systolic blood pressure (SBP) during low intensity resistance training were always larger than during high intensity (P<0.001). Peak SBP increased from set 1 to set 3 and 4 during both low and high intensity resistance training (P<0.05). Peak HR was larger in set 4 (95 ± 11 bpm) than in set 1 only during low intensity resistance training (91 ± 12 bpm) (P<0.05). One-minute recovery periods did not allow a return to baseline HR and SBP during both low and high intensity modalities.

Conclusions

The SBP and HR responses to resistance training are related to the duration of exercise. Sets with ≥ 10 repetitions of high intensity should be preferred to longer sets with low intensity. Pauses between exercise sets should exceed 1 min. Blood pressure should be measured during the last repetitions of the exercise set. Eur J Cardiovasc Prev Rehabil 12:12-17 © 2005 The European Society of Cardiology

POWERLIFTING SESSIONS PROMOTE SIGNIFICANT POST-EXERCISE HYPOTENSION

ABSTRACT Introduction: Powerlifting (PWL) is a worldwide method, frequently used in resistance training programs. However, the relationship between cardiovascular responses and PWL is still unclear in the literature. Objective: To evaluate acute cardiovascular overload and post-exercise hypotension (PEH) after acute powerlifting exercise session in subjects with experience in the modality. Methods: Nine powerlifting athletes (34 ± 5 years) participated voluntarily in this study. The following exercises were used in the session: squat, bench press and deadlift (95% of 1 RM, 2 to 5 repetitions). The anthropometric parameters and blood pressure (systolic, diastolic and mean) were evaluated immediately, 5', 10', 30', 60' and 24 hours after the exercise session with a non-invasive automatic pressure monitor. Results: Significant differences (p<0.05) were found between rest and immediately after exercise on systolic (135 ± 6 vs. 153 ± 10 mmHg) and mean (102 ± 3 vs. 108 ± 3 mmHg) blood pressures, but no difference was found at diastolic (85 ± 3 vs. 85 ± 4 mmHg) blood pressure. Additionally, the increase in systolic pressure did not reach values considered as a risk of cardiovascular overload. Significant PEH was found after 60 minutes (systolic: -12 ± 12%, diastolic: -5 ± 6% and mean: -7 ± 5%) and 24 hours after PWL session (systolic: -5 ± 4%, diastolic: -8 ± 4% and mean: -7 ± 3%). Conclusion: Our data demonstrated that a PWL session does not increase systolic blood pressure up to the risk range and promotes PEH after 60 minutes of exercise and that this cardiovascular response persisted after 24 hours post-exertion in powerlifting athletes.

Hypertension and Exercise Training: Evidence from Clinical Studies

Hypertension is a worldwide prevalent disease, mostly manifested as its primary ethiology, characterized by a chronic, multifactorial, asymptomatic, and usually incurable state. It is estimated that more than one billion of the world population is hypertensive. Also, hypertension is the main cause of the two most frequent causes of death worldwide: myocardial infarction and stroke. Due to the necessity of the cardiovascular system to manage chronically increased levels of blood pressure, hypertension causes severe alterations in multiple organs, as the heart, vessels, kidneys, eyes and brain, thus increasing the risk of health complications. The heart is the main target organ and suffers several adaptations to compensate the increased blood pressure levels; nevertheless, long-term adaptations without proper control are extremely harmful to cardiovascular health. On the other hand, hypertension is a modifiable risk factor and its adequate control is highly dependent on lifestyle. Pharmacological treatment is of great success when adherence is high. Several classes of antihypertensive drugs are prescribed and can effectively maintain blood pressure within acceptable levels. However, non-pharmacological methods, as diet and exercise training, can not only optimize the treatment but also prevent or postpone hypertension development as well as its complications, acting as important complements to the ideal control of elevated blood pressure, and bringing together benefits beyond blood pressure decrease, as a general health status improvement and increased quality of life. There is consistent evidence that regular exercise training promotes several benefits when properly prescribed and practised, acting as "medicine" for dozens of chronic diseases. The effects of exercise training in blood pressure levels and in its mechanisms of control are of clinical relevance and efficacy. This chapter will describe the classical and recent results on the beneficial effects of different modalities of exercise training in the cardiovascular system of human primary hypertension, focusing on the mechanisms influenced by exercise training which help to decrease blood pressure and improve the cardiovascular system.

Set Configuration in Resistance Exercise: Muscle Fatigue and Cardiovascular Effects

Purpose

Cardiovascular responses of traditional resistance (TS) training have been extensively explored. However, the fatigue mechanisms associated with an intra-set rest configuration (ISR) have not been investigated. This study compares two modalities of set configurations for resistance exercise that equates work to rest ratios and measures the central and peripheral fatigue in combination with cortical, hemodynamic and cardiovascular measures.

Methods

11 subjects performed two isometric knee extension training sessions using TS and ISR configurations. Voluntary activation (VA), single twitch amplitude, low frequency fatigue (LFF), Mwave, motor evoked potential (MEP), short intracortical inhibition (SICI), intracortical facilitation (ICF) and heart rate variability were evaluated before and after each training session. During each session beat to beat heart rate, blood pressure and rate pressure product (RPP) were also evaluated.

Results

After exercise VA decreased significantly for TS but not for ISR (P < 0.001), single twitch amplitude and LFF values were lower for TS than ISR (P < 0.004), and SICI was reduced only for the TS configuration (P = 0.049). During exercise RPP values were significantly higher for the TS than for ISR (P = 0.001). RPP correlated with VA for TS (r = -.85 P < 0.001) suggesting a relationship between central fatigue and cardiovascular stress.

Conclusions

We conclude that ISR induced lower central and peripheral fatigue as well as lower cardiovascular stress in comparison with TS configuration. Our study suggests that set configuration is a key factor in the regulation of the neuromuscular and cardiovascular responses of resistance training.

The Acute Risks of Exercise in Apparently Healthy Adults and Relevance for Prevention of Cardiovascular Events

BACKGROUND

Increased physical activity (PA) is associated with improved quality of life and reductions in cardiovascular (CV) morbidity and all-cause mortality in the general population in a dose-response manner. However, PA acutely increases the risk of adverse CV event or sudden cardiac death (SCD) above levels expected at rest. We review the likelihood of adverse CV events related to exercise in apparently healthy adults and strategies for prevention, and contextualize our understanding of the long-term risk reduction conferred from PA.

METHODS

A systematic review of the literature was performed using electronic databases; additional hand-picked relevant articles from reference lists and additional sources were included after the search.

RESULTS

The incidence of adverse CV events in adults is extremely low during and immediately after PA of varying types and intensities and is significantly lower in those with long-standing PA experience. The risk of SCD and nonfatal events during and immediately after PA remains extremely low (well below 0.01 per 10,000 participant hours); increasing age and PA intensity are associated with greater risk. In most cases of exercise-related SCD, occult CV disease is present and SCD is typically the first clinical event.

CONCLUSIONS

Exercise acutely increases the risk of adverse CV events, with greater risk associated with vigorous intensity. The risks of an adverse CV event during and immediately after exercise are outweighed by the health benefits of vigorous exercise performed regularly. A key challenge remains the identification of occult structural heart disease and inheritable conditions that increase the chances of lethal arrhythmias during exercise.

Participation in muscle-strengthening activities as an alternative method for the prevention of multimorbidity

OBJECTIVE

Participating in muscle-strengthening activities (MSA) has been shown to reduce the risks associated with many individual chronic diseases; however, the impact of MSA on multimorbidity remains unexplored. Therefore, the purpose of this study was to determine the association between MSA and multimorbidity.

METHODS

Data from the 2003-2006 NHANES were used including 4587 adults (≥20 years old). Participation in MSA was defined as self-reported involvement within the last 30 days. Multimorbidity was deemed as having ≥2 of the 14 chronic diseases.

RESULTS

After adjustments (including accelerometry-assessed physical activity), individuals participating in MSA had a 26% reduced odds of having multimorbidity (OR=0.74; 95% CI: 0.62-0.88; p=0.001) and each 2 day/week increase in MSA was associated with an 8% reduced odds of being multimorbid (OR=0.92; 95% CI: 0.84-1.00; p=0.05).

CONCLUSION

Independent of accelerometry-assessed physical activity, the participation in MSA may reduce the odds of being multimorbid, with evidence of a dose-response relationship.

Difference between old and young adults in contribution of β-cell function and sarcopenia in developing diabetes mellitus

AIMS/INTRODUCTION

To investigate the difference in contributing factors in developing diabetes between old and young adults.

MATERIALS AND METHODS

Subjects with recent-onset diabetes were selected from a nationwide survey data and classified according to age: elderly (age ≥75 years), middle-age (age 45-64 years) and young (age 25-39 years). The homeostasis model assessment of insulin resistance and β-cell function were calculated. Sarcopenia was assessed using dual-energy X-ray absorptiometry.

RESULTS

The prevalence of recent-onset diabetes was 13.5%, 8.0%, and 1.4% in patients aged ≥75 years (unweighted n = 1,082), 45-64 years (unweighted n = 6,532), and 25-39 years (unweighted n = 5,178), respectively. Homeostasis model assessment of β-cell function along with homeostasis model assessment of insulin resistance showed increasing trends as onset age increased in recent-onset diabetes (P for trend < 0.001 in both). Elderly-onset diabetic patients had significantly higher homeostasis model assessment of β-cell function and homeostasis model assessment of insulin resistance compared with the middle-age-onset group (P < 0.001 and 0.014, respectively). Multivariate analysis showed that sarcopenia was significantly associated with recent-onset diabetes only in patients aged ≥75 years (odds ratio [OR] 2.478, 95% confidence interval [CI] 1.379-4.452) but not in patients aged 45-64 years. In the middle-age group, abdominal obesity (OR 2.933, 95% CI 2.086-4.122), hypertriglyceridemia (OR 1.529, 95% CI 1.078-2.169]) and low high-density lipoprotein cholesterolemia (OR 1.930, 95% CI 1.383-2.695) were associated with recent-onset diabetes.

CONCLUSIONS

Elderly-onset diabetic patients had higher insulin resistance and relatively preserved β-cell function compared with middle-age-onset patients. Sarcopenia might play a more important role in developing diabetes in the elderly population.

Amlodipine reduces blood pressure during dynamic resistance exercise in hypertensive patients

This study investigated the effect of the dihydropyridine calcium channel antagonist, amlodipine, on blood pressure (BP) during resistance exercise performed at different intensities in hypertensives. Eleven hypertensives underwent 4 weeks of placebo and amlodipine (random double-blinded crossover design). In each phase, they performed knee extension exercise until exhaustion following three protocols: one set at 100% of 1 RM (repetition maximum), three sets at 80% of 1 RM, and three sets at 40% of 1 RM. Intraarterial BP was measured before and during exercise. Amlodipine reduced maximal systolic/diastolic BP values achieved at all intensities (100% = 225 ± 6/141 ± 3 vs. 207 ± 6/130 ± 6 mmHg; 80% = 289 ± 8/178 ± 5 vs. 273 ± 10/169 ± 6 mmHg; 40% = 289 ± 10/176 ± 8 vs. 271 ± 11/154 ± 6 mmHg). Amlodipine blunted the increase in diastolic BP that occurred during the second and third sets of exercise at 40% of 1RM (+75 ± 6 vs. +61 ± 5 mmHg and +78 ± 7 vs. +64 ± 5 mmHg, respectively). Amlodipine was effective in reducing the absolute values of systolic and diastolic BP during resistance exercise and in preventing the progressive increase in diastolic BP that occurs over sets of low-intensity exercise. These results suggest that systemic vascular resistance is involved in BP increase during resistance exercise, and imply that hypertensives receiving amlodipine are at lower risk of increased BP during resistance exercise than non-medicated patients.

Effects of creatine supplementation on oxidative stress profile of athletes

Background

Creatine (Cr) supplementation has been widely used among athletes and physically active individuals. Secondary to its performance-enhancing ability, an increase in oxidative stress may occur, thus prompting concern about its use. The purpose of this study is to investigate the effects of Cr monohydrate supplementation and resistance training on muscle strength and oxidative stress profile in healthy athletes.

Methods

A randomized, double-blind, placebo-controlled method was used to assess twenty-six male elite Brazilian handball players divided into 3 groups: Cr monohydrate supplemented group (GC, N = 9), placebo group (GP, N = 9), no treatment group (COT, N = 8) for 32 days. All subjects underwent a resistance training program. Blood samples were drawn on 0 and 32 days post Cr supplementation to analyze the oxidative stress markers, thiobarbituric acid reactive species (TBARS), total antioxidant status (TAS), and uric acid. Creatine phosphokinase, urea, and creatinine were also analyzed, as well. Fitness tests (1 repetition maximum - 1RM and muscle endurance) were performed on the bench press. Body weight and height, body fat percentage (by measuring skin folds) and upper muscular area were also evaluated. Statistical analysis was performed using ANOVA.

Results

Only GC group showed increase in 1RM (54 ± 9 vs. 63 ± 10 kg; p = 0.0356) and uric acid (4.6 ± 1.0 vs. 7.4 ± 1.6 mg/dl; p = 0.025), with a decrease in TAS (1.11 ± 0.34 vs. 0.60 ± 0.19 mmol/l; p = 0.001). No differences (pre- vs. post-training) in TBARS, creatine phosphokinase, urea, creatinine, body weight and height, body fat percentage, or upper muscular area were observed in any group. When compared to COT, GC group showed greater decrease in TAS (−0.51 ± 0.36 vs. -0.02 ± 0.50 mmol/l; p = 0.0268), higher increase in 1RM (8.30 ± 2.26 vs. 5.29 ± 2.36 kg; p = 0.0209) and uric acid (2.77 ± 1.70 vs. 1.00 ± 1.03 mg/dl; p = 0.0276).

Conclusion

We conclude that Cr monohydrate supplementation associated with a specific resistance program promoted a meaningful increase in muscle strength without inducing changes in body composition. The observed significant increase in uric acid and the decrease in TAS suggest that creatine supplementation, despite promoting acute effects on muscle strength improvement, might induce oxidative stress and decreases total antioxidant status of subjects.

Intensidades de treinamento resistido e pressão arterial de idosas hipertensas - um estudo piloto

INTRODUÇÃO: Observa-se que a literatura apresenta uma lacuna acerca da intensidade ideal de treinamento resistido para idosos hipertensos, os poucos estudos existentes utilizam treinamentos com diferentes intensidades. OBJETIVO: Verificar o efeito de duas intensidades de treinamento resistido sobre a pressão arterial de idosas hipertensas controladas. Métodos: Dezesseis idosas hipertensas, controladas por medicação anti-hipertensiva, foram divididas em dois grupos através de sorteio. Nove pacientes foram submetidas a treinamento resistido moderado (G1) e sete, a treinamento resistido leve (G2). As pacientes realizaram oito semanas de treinamento resistido, com frequência de três vezes por semana em dias alternados, no período vespertino. Os exercícios realizados foram respectivamente: leg press, supino reto, extensão de joelhos, puxada frontal, flexão de joelhos, abdução de ombro, abdução unilateral de quadril com cross over e rosca direta com barra. RESULTADOS: As pacientes do G1 apresentaram redução tanto nos valores de repouso da pressão arterial diastólica (PAD) p < 0,03, como da pressão arterial média (PAM) p < 0,03. O G2, por sua vez, apresentou redução nos valores de repouso da PAM (p < 0,03) e uma tendência à redução na PAD (p < 0,06). A magnitude de queda em ambos os grupos foi superior aos valores apresentados na literatura. CONCLUSÂO: Tanto o treinamento resistido moderado quanto o leve, mesmo quando iniciados na terceira idade, promoveram benefícios cardiovasculares. Ambos podem ser indicados como tratamento coadjuvante para idosas hipertensas controladas por medicação.

Different cardiovascular responses to a resistance training session in hypertensive women receiving propanolol compared with normotensive controls

The aim of the present study was to compare the responses of blood pressure, heart rate, and rate-pressure product of hypertensive women using beta-blockers with healthy controls during resistance exercise (by the end of the concentric phase of the contractions) and in the postexercise period (5 and 30 minutes after). Ten untrained normotensive women (N) and 10 mildly hypertensive females receiving 40 mg/day of propanolol (H) were selected. Three sets of 10 repetitions at 80% of 10 repetitions maximum with 30 s rest interval were performed on the leg press exercise. The H group exhibited lower systolic blood pressure after the second set compared with N. Heart rate and rate-pressure product were lower in H in all analyzed periods compared with N. Propanolol attenuates the cardiovascular response to a leg press resistance exercise in mildly hypertensive women.

Physical fitness in patients with ankylosing spondylitis: comparison with population controls

BACKGROUND

Although flexibility traditionally has been the main focus for physical therapy in patients with ankylosing spondylitis (AS), there is now evidence for an increased risk of cardiovascular diseases (CVDs) in this group.

OBJECTIVE

The purposes of this study were: (1) to compare physical fitness (cardiorespiratory fitness, muscular capacity, flexibility, and balance) in patients with AS and controls and (2) to explore associations between physical fitness and disease activity in the patient group.

DESIGN

This was a cross-sectional study.

METHODS

The physical fitness variables were cardiorespiratory fitness (treadmill test for estimation of peak oxygen uptake [V(O(2))peak]), muscular capacity (push-ups test), balance (30-second single-leg stand and walking in a figure-of-eight pattern), and flexibility (Bath Ankylosing Spondylitis Metrology Index [BASMI]). The Ankylosing Spondylitis Disease Activity Score (ASDAS) was used to assess disease activity. Group differences and associations were tested with the chi-square test for categorical variables, the Mann-Whitney U test for ordinal variables, and analysis of covariance for continuous variables.

RESULTS

One hundred forty-nine of 250 of the invited patients with AS and 133 of 329 of the invited controls were included in the study. The mean ASDAS score of the patient group was 2.3 (range=0.5-4.7), and the median disease duration was 23 years (range=7-55). The patient group had significantly lower V(O(2)) peak values, with a mean difference of -2.7 mL·kg(-1)·min(-1) (95% confidence interval=-4.3, -1.1), and higher BASMI scores, with a mean difference of 1.6 (95% confidence interval=1.5, 1.8), compared with the control group. No group differences were found in balance or muscular capacity. In the patient group, significant inverse associations were found between ASDAS scores and V(O(2))peak and muscular capacity.

LIMITATIONS

The response rate was lower in the control group (40.4%) than in the patient group (59.6%).

CONCLUSION

The lower cardiorespiratory fitness and reduced flexibility in the AS group indicate that physical therapy programs should include cardiorespiratory fitness exercises as a basic component to reduce the risk of cardiovascular disease.

Evidence-based risk assessment and recommendations for exercise testing and physical activity clearance in apparently healthy individuals1This paper is one of a selection of papers published in this Special Issue, entitled Evidence-based risk assessment and recommendations for physical activity clearance, and has undergone the Journal’s usual peer review process

Increased physical activity (PA) is associated with improved health and quality of life in the general population. A dose–response effect is evident between increasing levels of PA participation and a lower relative risk for cardiovascular disease and all-cause mortality. However, there is also clear evidence that PA acutely increases the risk of an adverse cardiovascular (CV) event and sudden cardiac death (SCD) significantly above levels expected at rest. Adverse CV events during PA may be triggered acutely by the physiological stress of exercise. This investigation will review the available literature describing the CV risks of exercise testing and PA participation in apparently healthy individuals. A systematic review of the literature was performed using electronic databases, including Medline, CINAHL, SPORT discus, EMBASE, Cochrane DSR, ACP Journal Club, and DARE; additional relevant articles were hand-picked and the final grouping was used for the review using the AGREE process to assess the impact and quality of the selected articles. Six hundred and sixteen relevant articles were reviewed with 51 being identified as describing adverse CV events during exercise and PA. Data suggests the risks of fatal and nonfatal events during maximal exercise testing in apparently healthy individuals rarely occur (approximately <0.8 per 10 000 tests or 1 per 10 000 h of testing). The incidence of adverse CV events is extremely low during PA of varying types and intensities, with data limited almost exclusively to fatal CV events, as nonfatal events are rarely reported. However, this risk is reduced by 25%–50% in those individuals who have prior experience with increased levels of PA, particularly vigorous PA. Throughout a wide age range, the risk of SCD and nonfatal events during PA remain extremely low (well below 0.01 per 10 000 participant hours), but both increasing age and PA intensity are associated with greater risk. In most cases of exercise-related SCD, undetected pre-existing disease is present and SCD is typically the first clinical event. The risks of an adverse CV event during exercise testing and PA are rare and are outweighed by the health benefits. Given this risk-benefit relationship, the PAR-Q is an appropriate method to identify those at higher risk across a wide age span and should be used in conjunction with appropriate clinical guidelines for guiding individuals towards graduated PA. There are not adequate data to describe the risks of PA in those individuals considered to be at higher risk but without cardiovascular disease.

Exercise programs in trials for patients with ankylosing spondylitis: do they really have the potential for effectiveness?

OBJECTIVE

To evaluate if exercise programs in trials for patients with ankylosing spondylitis (AS) have the potential for effectiveness.

METHODS

A systematic literature search was performed and randomized trials examining the effectiveness of exercise programs for AS patients were analyzed according to 3 elements: whether the exercise programs were designed according to the American College of Sports Medicine (ACSM) recommendations for developing cardiorespiratory fitness, muscular strength, and flexibility; whether physiologic responses were properly measured; and whether adherence to programs was monitored.

RESULTS

Twelve trials with a total of 826 AS patients were evaluated. Five trials included cardiorespiratory exercise as a part of the exercise programs. One of these met the ACSM recommendations for intensity, duration, frequency, and length of the exercise period. This trial showed the greatest within-group improvement in aerobic capacity (effect size [ES] 2.19). Five trials included muscular strength training, but none measured the physiologic responses nor met the recommendations for improving muscular strength. Eleven trials included flexibility training, but the programs were poorly described overall. Small improvements in spinal mobility (ES range 0.02-0.67) were reported in all trials. Finally, 4 trials reported on participants' adherence to the exercise programs, but only 1 provided sufficient information to evaluate the possible influence of the adherence.

CONCLUSION

The quality of interventions in exercise trials for patients with AS can be improved. Future trials should also focus on measuring and reporting physiologic responses and adherence to exercise interventions.

Exercícios resistidos terapêuticos para indivíduos com doença arterial obstrutiva periférica: evidências para a prescrição

A prática regular de exercícios é parte do tratamento clínico inicial para pacientes com doença arterial obstrutiva periférica. Nesse sentido, a utilização de exercícios contra resistência (exercícios resistidos) tem sido amplamente recomendada para diferentes populações, especialmente para pessoas idosas com e sem doenças associadas. Os poucos trabalhos encontrados utilizando essa forma de exercícios em pacientes com doença arterial obstrutiva periférica documentam a sua eficiência terapêutica. No entanto, os efeitos documentados dos exercícios resistidos em outras populações têm evidenciado melhoria da aptidão física e da qualidade de vida, com segurança cardiovascular e músculo-esquelética. Essas informações fornecem indicativos sobre os possíveis benefícios dos exercícios resistidos na terapia de indivíduos com doença arterial obstrutiva periférica. Nesse sentido, esta revisão objetivou apresentar informações científicas que permitam auxiliar a prescrição dos exercícios resistidos para essa população.

Resistance exercise in individuals with and without cardiovascular disease: 2007 update: a scientific statement from the American Heart Association Council on Clinical Cardiology and Council on Nutrition, Physical Activity, and Metabolism

Prescribed and supervised resistance training (RT) enhances muscular strength and endurance, functional capacity and independence, and quality of life while reducing disability in persons with and without cardiovascular disease. These benefits have made RT an accepted component of programs for health and fitness. The American Heart Association recommendations describing the rationale for participation in and considerations for prescribing RT were published in 2000. This update provides current information regarding the (1) health benefits of RT, (2) impact of RT on the cardiovascular system structure and function, (3) role of RT in modifying cardiovascular disease risk factors, (4) benefits in selected populations, (5) process of medical evaluation for participation in RT, and (6) prescriptive methods. The purpose of this update is to provide clinicians with recommendations to facilitate the use of this valuable modality.

Active lifestyle protects against incident low back pain in seniors: a population-based 2-year prospective study of 1387 Danish twins aged 70-100 years

STUDY DESIGN

Prospective cohort study of twins.

OBJECTIVES

To investigate associations between physical activity, physical function, and incident low back pain (LBP) in an elderly population.

SUMMARY OF BACKGROUND DATA

The relationship between an active lifestyle and LBP in seniors is unknown.

METHODS

Participants in the population-based Longitudinal Study of Aging Danish Twins free from LBP at baseline (no LBP during the past month) were included, and interview data on physical activity, overall physical function, and LBP at baseline and follow-up were obtained. Associations between levels of physical activity and LBP were estimated using logistic regression for the entire cohort, and using a matched case-control design for twin pairs discordant for physical activity. Absolute risk and relative risks for incident LBP in relation to physical activity were calculated for participants with higher or lower than average physical function at baseline. Absolute risk for LBP was also calculated for participants based on whether they remained active or inactive between baseline and follow-up or changed activity level.

RESULTS

A total of 1387 persons aged 70-100 at baseline were included in the analyses, including 86 twin pairs discordant for physical activity at baseline. In the total sample, 83% were engaged in light physical activity, and 42% of men and 35% of women were engaged in strenuous physical activity at least weekly. Being engaged in strenuous physical activity at baseline was strongly protective in relation to both having had any LBP (odds ratio 0.21, 95% confidence interval 0.12-0.37 for intra-pair analysis) and having had LBP lasting more than 30 days altogether during the past year at follow-up (odds ratio 0.08, 95% confidence interval 0.03-0.18 for intra-pair analysis). Statistically significant dose-response associations between increasing frequency of strenuous physical activity and magnitude of this protective effect were found. Participants with poor initial physical function experienced the strongest protective effect of strenuous physical activity. Finally, LBP does not appear to be an important factor affecting whether participants remained engaged in strenuous physical activity at baseline and follow-up or vice versa.

CONCLUSIONS

Strenuous physical activity at least once a week is protective for incident LBP in seniors.

Exercise and the heart failure patient: aerobic vs strength training--is there a need for both?

Heart failure (HF) is characterized by general muscular weakness, muscle atrophy, and exercise intolerance that lead to reductions in functional capacity, ability to perform activities of daily living, and health-related quality of life. Until recently, exercise programs for patients with HF were centered on aerobic exercise training alone. Although many activities of daily living require significant muscle strength, the role of strength training for HF patients, either alone or in combination with aerobic exercise, has not been well studied. There is suggestive evidence that combined strength-aerobic exercise training may offer additional benefits in terms of health-related quality of life and functional capacity. Strength training can be targeted to reduce muscle atrophy to a greater extent than aerobic training. Further research is required to isolate the specific role of strength training regarding improvements in prognosis, HF-related morbidity and hospitalization, and health-related quality of life for patients with HF.

Cardiac Autonomic Modulation Following High-Intensity Static Muscle Contractions

BACKGROUND

The purpose of this investigation was to examine cardiac autonomic modulation, as measured by wavelet analysis of heart rate variability, following a series of high-intensity static muscle contractions.

METHODS

After 10 minutes of rest, electrocardiograms (ECGs) were collected in 17 participants (age, 24.5 +/- 1 yr) 2.5 minutes before (REST) and 10 minutes after a series of static contractions of the knee extensors. Participants performed contractions with the nondominant leg (knee fixed at 90 degrees) at either 70% or 85% (randomized order) of their maximal voluntary contraction (MVC) on two separate visits. The postexercise ECGs were further divided into four consecutive 2.5-minute segments (POST 1-POST 4) to evaluate the time course of any possible autonomic changes after exercise. Each 2.5-minute segment was evaluated for the standard deviation of normal RR intervals (SDNN) and the percentage of successive RR intervals that differed by more than 50 ms (pNN50). Frequency-domain indices were obtained via wavelet transformation giving coefficients that reflected high- and low-frequency fluctuations in heart period (HFw and LFw).

RESULTS

SDNN was elevated during POST-1 and pNN50 was reduced during POST-3 and POST-4 (P < 0.05) compared to REST for both intensities. Furthermore, HFw and LFw were increased during POST-1 and reduced during POST-3 and POST-4 compared to REST for both intensities (P < 0.05).

CONCLUSION

These data suggest that complex alterations cardiac autonomic modulation exist for at least 10 minutes following a series of high-intensity static contractions performed at either 70% or 85% of MVC.