Exercise prescription for the prevention and treatment of cardiovascular diseases: part II

Sports behaviour among HIV-infected versus non-infected individuals in a Berlin cohort

Physical activity has been recommended based on beneficial effects described in HIV-infected patients. However, such guidelines do not take into account actual sport behaviours and general attitudes towards physical activity. To evaluate actual sport activity and attitudes towards sport in HIV-infected versus non-infected individuals we conducted an anonymous questionnaire investigating the prevalence, as well as possible changes, in sports engagement and the overall attitude to physical activity. A total of 283 patients of a general care facility specialized in the treatment of HIV/AIDS in Berlin, Germany, participated; 124 were HIV infected and 159 were non-infected, mostly men who have sex with men (MSM) (88%), with a median age of 35 years. The HIV-infected participants had a median CD4+ count of 554 cells/µL and 48.8% of them were using antiretroviral therapy (ART) at the time of survey. The proportion of patients actually performing physical activity was significantly lower (P = 0.028) within the HIV-infected group (61.3%) than within the non-infected group (74.2%). This difference remained significant after accounting for possible confounders such as age, gender, injecting drug use and sexual preferences. Previously reported sport activity prevalence was similar in both groups on leaving school. From our data we could not identify an association between the time of HIV diagnosis and changes in sports activity. In conclusion, fewer HIV-infected individuals report physical activity than non-infected individuals. Sociodemographic studies to evaluate potential differences in sports behaviour are required in order to inform exercise guidelines for HIV-infected patients.

Diving bradycardia: a mechanism of defence against hypoxic damage

A feature of all air-breathing vertebrates, diving bradycardia is triggered by apnoea and accentuated by immersion of the face or whole body in cold water. Very little is known about the afferents of diving bradycardia, whereas the efferent part of the reflex circuit is constituted by the cardiac vagal fibres. Diving bradycardia is associated with vasoconstriction of selected vascular beds and a reduction in cardiac output. The diving response appears to be more pronounced in mammals than in birds. In humans, the bradycardic response to diving varies greatly from person to person; the reduction in heart rate generally ranges from 15 to 40%, but a small proportion of healthy individuals can develop bradycardia below 20 beats/min. During prolonged dives, bradycardia becomes more pronounced because of activation of the peripheral chemoreceptors by a reduction in the arterial partial pressure of oxygen (O2), responsible for slowing of heart rate. The vasoconstriction is associated with a redistribution of the blood flow, which saves O2 for the O2-sensitive organs, such as the heart and brain. The results of several investigations carried out both in animals and in humans show that the diving response has an O2-conserving effect, both during exercise and at rest, thus lengthening the time to the onset of serious hypoxic damage. The diving response can therefore be regarded as an important defence mechanism for the organism.

Physical activity and late effects in childhood acute lymphoblastic leukemia long-term survivors

In the present study the authors evaluated therapy-related long-term adverse effects and physical activity in a cohort of long-term survivors of childhood acute lymphoblastic leukemia (ALL), diagnosed in their center between March 1991 and August 2000, treated according to the AIEOP (Associazione Italiana di Ematologia e Oncologia Pediatrica) ALL 91 or 95 study protocol and regularly seen in the authors' long-term follow-up unit. The authors analyzed the long-term sequelae of major body systems in this cohort of subjects and administered an "ad hoc" questionnaire concerning sport. The authors found that 70 patients out of 102 (68.5%) showed no late effects, 10% presented only instrumental or neuropsychological test abnormalities, and 21.5% had 1 or more clinical late sequelae. None of the evidenced late effects represented a contraindication to do physical activity. Sixty-one percent of survivors do physical activity, most of them regularly. Sixty-one percent of males and 18.5% of females (P < .005) do competitive sport (sports rates are similar to those of the general age-matched population). Nearly all subjects spontaneously choose to do sport and think physical exercise is an important and useful resource for their health. The authors conclude that the more recent therapy regimens for leukemia treatment, excluding bone marrow transplantation, do not seem to cause such late effects as to prevent survivors from doing sport. Therefore, in the care of ALL survivors, physical activity is not only not contraindicated, but should also be promoted as much as possible. The development of specific educational programs is warranted as part of the care of cancer survivors.

Special needs to prescribe exercise intensity for scientific studies

There is clear evidence regarding the health benefits of physical activity. These benefits follow a dose-response relationship with a particular respect to exercise intensity. Guidelines for exercise testing and prescription have been established to provide optimal standards for exercise training. A wide range of intensities is used to prescribe exercise, but this approach is limited. Usually percentages of maximal oxygen uptake (VO₂) or heart rate (HR) are applied to set exercise training intensity but this approach yields substantially variable metabolic and cardiocirculatory responses. Heterogeneous acute responses and training effects are explained by the nonuniform heart rate performance curve during incremental exercise which significantly alters the calculations of %HR_max and %HRR target HR data. Similar limitations hold true for using %VO_2max and %VO₂R. The solution of these shortcomings is to strictly apply objective submaximal markers such as thresholds or turn points and to tailor exercise training within defined regions.

Honokiol protects rats against eccentric exercise-induced skeletal muscle damage by inhibiting NF-kappaB induced oxidative stress and inflammation

Honokiol, a bioactive component isolated from the Chinese herb Magnolia officinalis, is known for its potent antioxidative and anti-inflammatory effects. To study whether honokiol can protect skeletal muscle from sports injuries, we set up an eccentric exercise bout protocol for rats consisting of downhill running on a treadmill and examined the effect of oral administration of honokiol at 1 h before eccentric exercise at a dose of 5 mg/kg on day 1 (HK5 x 1) or 1 mg/kg/day for 5 consecutive days (HK1 x 5). Eccentric exercise was implemented for 3-5 consecutive days, and induced remarkable tissue damage. This damage was associated with an increase in serum creatine levels, increase in protein nitrotyrosylation, poly-ADP-ribose-polymerase (PARP) upregulation, lipid peroxidation, and leukocyte infiltration. The degree of muscle damage also paralleled dramatic gene expression for cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and inflammation-associated cytokines (interleukin (IL)-1beta, IL-6, tumor necrosis factor-alpha, and monocyte chemoattractant protein-1), possibly through activation of nuclear factor kappa-B (NF-kappaB), a crucial proinflammatory transcription factor. Both honokiol treatments (HK5 x 1 and HK1 x 5) significantly ameliorated eccentric exercise-induced muscle damage as revealed by suppression of cell fragmentation, protein nitrotyrosylation and PARP upregulation, as well as reductions in lipid peroxidation and leukocyte infiltration, possibly through downregulating gene expression for COX-2, iNOS, and the proinflammatory cytokines by modulation of NF-kappaB activation. In conclusion, the present study demonstrates for the first time that honokiol exhibits protective effects against eccentric exercise-induced skeletal muscle damage in rats, probably by modulating inflammation-mediated damage to muscle cells.

Influences of lifestyle and general practice (GP) care on the symptom profile of people with panic disorder

Current treatment guidelines for anxiety disorders, including panic disorder (PD), recommend either medication or cognitive behavioural therapy (CBT). There is currently a call through the Layard Report for significant investment to increase the availability of CBT resources. However, there are reported limitations to both medication and CBT in the treatment of anxiety, and it appears prudent to consider additional methods of treatment that may offer effective interventions. One such intervention is based around the evidence of altered sensitivity within a number of physiological body systems in anxiety patients (particularly those with PD), all of which are influenced in their function by habitual lifestyle behaviours. A randomised controlled trial compared a 16‐week occupational therapy‐led lifestyle intervention and routine general practice (GP) care for PD. At 20 weeks, 14 symptoms with ‘moderate’ to ‘very severe’ ratings were assessed in 36 GP and 31 lifestyle‐intervention patients. Composite symptom profiles, similar at baseline, were produced. The GP intervention produced modest improvements in most symptoms. The lifestyle intervention overall produced greater symptomatic relief (Wilcoxon signed ranks test, P= 0.008). The physiological and cognitive symptom profile also changed more with lifestyle intervention. Occupational therapists have developed their interventions based on their understanding of everyday occupation. Habitual lifestyle behaviours are characterised as being recurrent elements of everyday occupation and are, therefore, legitimate targets for occupational therapy interventions. They provide a vehicle through which to encourage patients to regain understanding and control of their own anxiety symptoms.