Continuous Hemodynamic Response to Maximal Dynamic Strength Testing in Older Adults

The Acute Cardiorespiratory and Cerebrovascular Response to Resistance Exercise

Resistance exercise (RE) is a popular modality for the general population and athletes alike, due to the numerous benefits of regular participation. The acute response to dynamic RE is characterised by temporary and bidirectional physiological extremes, not typically seen in continuous aerobic exercise (e.g. cycling) and headlined by phasic perturbations in blood pressure that challenge cerebral blood flow (CBF) regulation. Cerebral autoregulation has been heavily scrutinised over the last decade with new data challenging the effectiveness of this intrinsic flow regulating mechanism, particularly to abrupt changes in blood pressure over the course of seconds (i.e. dynamic cerebral autoregulation), like those observed during RE. Acutely, RE can challenge CBF regulation, resulting in adverse responses (e.g. syncope). Compared with aerobic exercise, RE is relatively understudied, particularly high-intensity dynamic RE with a concurrent Valsalva manoeuvre (VM). However, the VM alone challenges CBF regulation and generates additional complexity when trying to dissociate the mechanisms underpinning the circulatory response to RE. Given the disparate circulatory response between aerobic and RE, primarily the blood pressure profiles, regulation of CBF is ostensibly different. In this review, we summarise current literature and highlight the acute physiological responses to RE, with a focus on the cerebral circulation.

Low-intensity resistance training with blood flow restriction improves vascular endothelial function and peripheral blood circulation in healthy elderly people

PURPOSE

The present study aimed to investigate the effects of low-intensity resistance training with blood flow restriction (BFR resistance training) on vascular endothelial function and peripheral blood circulation.

METHODS

Forty healthy elderly volunteers aged 71 ± 4 years were divided into two training groups. Twenty subjects performed BFR resistance training (BFR group), and the remaining 20 performed ordinary resistance training without BFR. Resistance training was performed at 20 % of each estimated one-repetition maximum for 4 weeks. We measured lactate (Lac), norepinephrine (NE), vascular endothelial growth factor (VEGF) and growth hormone (GH) before and after the initial resistance training. The reactive hyperemia index (RHI), von Willebrand factor (vWF) and transcutaneous oxygen pressure in the foot (Foot-tcPO2) were assessed before and after the 4-week resistance training period.

RESULTS

Lac, NE, VEGF and GH increased significantly from 8.2 ± 3.6 mg/dL, 619.5 ± 243.7 pg/mL, 43.3 ± 15.9 pg/mL and 0.9 ± 0.7 ng/mL to 49.2 ± 16.1 mg/dL, 960.2 ± 373.7 pg/mL, 61.6 ± 19.5 pg/mL and 3.1 ± 1.3 ng/mL, respectively, in the BFR group (each P < 0.01). RHI and Foot-tcPO2 increased significantly from 1.8 ± 0.2 and 62.4 ± 5.3 mmHg to 2.1 ± 0.3 and 68.9 ± 5.8 mmHg, respectively, in the BFR group (each P < 0.01). VWF decreased significantly from 175.7 ± 20.3 to 156.3 ± 38.1 % in the BFR group (P < 0.05).

CONCLUSIONS

BFR resistance training improved vascular endothelial function and peripheral blood circulation in healthy elderly people.

Segurança, reprodutibilidade, fatores intervenientes e aplicabilidade de testes de 1-RM

Um dos métodos mais utilizados para mensuração da força muscular é o teste de uma repetição máxima (1-RM), tendo em vista a sua versatilidade para aplicação em diferentes exercícios, a especificidade do movimento e o baixo custo operacional. Neste trabalho discutimos as evidências disponíveis a respeito da segurança, da reprodutibilidade, dos fatores intervenientes e da aplicabilidade prática do teste de 1-RM. Com base nas informações disponíveis até o presente momento, o teste de 1-RM parece ser um método seguro do ponto de vista ortopédico e cardiovascular e a sua reprodutibilidade depende, fundamentalmente, da realização de procedimentos de testagem adequados para a estabilização da carga, assim como do controle dos fatores intervenientes os quais podem influenciar no desempenho do teste. Embora a aplicabilidade para o diagnóstico e acompanhamento da força muscular seja ampla, a utilização de testes de 1-RM para a prescrição de treinamento com pesos ainda é bastante discutível.

Resistance training improves cardiac output, exercise capacity and tolerance to positive airway pressure in Fontan physiology

BACKGROUND

Subjects with Fontan-type circulation have no sub-pulmonary ventricle and thus depend exquisitely on the respiratory bellows and peripheral muscle pump for cardiac filling. We hypothesised that resistance training to augment the peripheral muscle pump might improve cardiac filling, reduce inspiratory-dependence of IVC return to the heart and thus improve exercise capacity and cardiac output on constant positive airway pressure (CPAP).

METHODS

Eleven Fontan subjects (32+/-2 years, mean+/-SEM) had cardiac magnetic resonance imaging (MRI) and exercise testing (CPET); six underwent 20 weeks of high-intensity resistance training; others were non-exercising controls. After training, CPET was repeated. Four trainers had MRI with real-time flow measurement at rest, exercise and on CPAP in the trained state and following a 12-month detrain.

RESULTS

In the trained state, muscle strength increased by 43% (p=0.002), as did total muscle mass (by 1.94 kg, p=0.003) and peak VO2 (by 183 ml/min, p=0.02). After detraining, calf muscle mass and peak workload had fallen significantly (p<0.03 for both) as did peak VO2 (2.72 vs. 2.18 l/min, p<0.001) and oxygen pulse, a surrogate for SV (16% lower, p=0.005). Furthermore after detraining, SV on MRI decreased at rest (by 11 ml, p=0.01) and during moderate-intensity exercise (by 16 ml, p=0.04); inspiratory-dependent IVC blood return during exercise was 40% higher (p=0.02). On CPAP, cardiac output was lower in the detrained state (101 vs. 77 ml/s, p=0.03).

CONCLUSIONS

Resistance muscle training improves muscle mass, strength and is associated with improved cardiac filling, stroke volume, exercise capacity and cardiac output on CPAP, in adults with Fontan-type circulation.

The blood pressure response of older men to maximum and sub-maximum strength testing

Strength testing is commonly used to determine the muscular strength of older individuals participating in a resistance training program. The purpose of this study was to non-invasively examine and compare the blood pressure (BP) and heart rate (HR) response of maximum and sub-maximum strength tests in older men. Twenty-four healthy men aged 70-80 yr were recruited for the study. Participants completed a 1 repetition maximum (RM) strength test and four days later a sub-maximum strength test on an incline squat. Systolic blood pressure (SBP), diastolic blood pressure (DBP) and HR were measured by plethysmography during and immediately after the strength tests. SBP, DBP and HR were (P<0.001) higher during the 1RM and sub-maximum strength tests compared to resting values. Twenty seconds post 1RM, SBP and HR were higher than resting values. Twenty seconds post sub-maximum strength testing SBP and DBP were lower (P<0.02) and HR (P<0.001) was higher than resting values. SBP, DBP and HR were higher (P<0.001) during sub-maximum strength testing compared to 1RM testing. Twenty seconds post testing, SBP and DBP were lower (P<0.001) and HR was higher (P<0.001) for the sub-maximum strength tests compared to the 1RM. The results of our study demonstrate that sub-maximum strength testing resulted in greater changes in BP and HR compared to 1RM strength testing. The lower cardiovascular stress experienced during the 1RM shows that this may be a safer method of testing compared to sub-maximum strength testing in men aged 70-80 yr.

Screening and evaluation of the cardiovascular and pulmonary systems in patients presenting with upper extremity impairments

NARRATIVE REVIEW: Given the prevalence of cardiovascular and pulmonary (CV-P) disease, it is likely that a substantial portion of patients seeking services from hand therapists have diagnosed or yet to be diagnosed disease in one or both of these systems. Pain originating from these systems is more common in the chest, shoulder, and scapular regions, but both systems can refer pain into the medial aspect of the forearm and hand. Pancoast's tumors of the lung, myocardial ischemia, and myocardial infarction are examples of specific pathologies capable of referring pain into these upper extremity regions. Another concern for the hand therapist is that upper extremity exercise is more stressful on the cardiovascular system than lower extremity exercise. Because of this, hand therapists need to be able to recognize when to discontinue or modify exercise interventions based on inappropriate cardiovascular system responses. Thus, the purpose of this review is to present 1) screening for potential pathology in the CV-P systems, 2) methods typically available to hand therapists for monitoring these systems, 3) criteria that indicate the need for therapy modification or medical referral, and 4) symptomatology of some common cardiac and pulmonary pathologic conditions the hand therapist may encounter.

LEVEL OF EVIDENCE

5.

Reprodutibilidade do teste de 1-RM em indivíduos com doença arterial obstrutiva periférica

INTRODUÇÃO: Indivíduos com doença arterial obstrutiva periférica (DAOP) apresentam atrofia muscular e redução da força de membros inferiores que, por sua vez, estão associadas às limitações na capacidade funcional. Consequentemente, a mensuração da força muscular pode ser útil na identificação dos níveis de força muscular e para monitorar as alterações na força em programas de intervenção. OBJETIVO: Analisar a reprodutibilidade do teste de uma repetição máxima (1-RM) em indivíduos com DAOP. Métodos: Fizeram parte da amostra 26 indivíduos com DAOP e sintomas de claudicação intermitente. Os indivíduos realizaram quatro sessões de teste de 1-RM no exercício extensão de joelhos unilateral, no membro com maior índice tornozelo-braço (ITB) e no membro com menor ITB. RESULTADOS: A força máxima aumentou significantemente da primeira para a segunda sessão de teste nos dois membros (4,1 ± 14,3% na perna com menor ITB e 5,9 ± 13,1% na perna com maior ITB). A análise dos limites de concordância revelou que, nos dois membros, as maiores diferenças médias e os maiores limites de concordância foram observados quando comparadas as sessões 1 e 2. CONCLUSÃO: A medida acurada da força máxima usando o teste de 1-RM, no exercício extensão de joelhos, em indivíduos com DAOP e sintomas de claudicação intermitente, é obtida quando duas sessões de testes de 1-RM são realizadas.