Exercise training below and above the lactate threshold in the elderly

In this study we report the effects of training at intensities below and above the lactate threshold on parameters of aerobic function in elderly subjects (age range 65-75 yr). The subjects were randomized into high-intensity (HI, N = 8; 75% of heart rate reserve = approximately 82% VO2max = approximately 121% of lactate threshold) and low-intensity (LI, N = 9; 35% of heart rate reserve = approximately 53% VO2max = approximately 72% of lactate threshold) training groups which trained 4 d.wk-1 for 30 min.session-1 for 8 wk. Before and after the training, subjects performed an incremental exercise test for determination of maximal aerobic power (VO2max) and lactate threshold (LT). In addition, the subjects performed a 6-min single-stage exercise test at greater than 75% of pre-training VO2max (SST-High) during which cardiorespiratory responses were evaluated each minute of the test. After training, the improvements in VO2max (7%) for LI and HI were not different from one another (delta VO2max for LI = 1.8 +/- 0.7 ml.kg-1.min-1; delta VO2max for HI = 1.8 +/- 1.0 ml.kg-1.min-1) but were significantly greater (P = 0.02) than the post-testing change observed in the control group (N = 8). Training improved the LT significantly (10-12%; P less than 0.01) and equally for both LI and HI (delta LT for for LI = 2.3 +/- 0.6 ml O2.kg-1.min-1; delta LT for HI = 1.8 +/- 0.8 ml O2.kg-1.min-1).(ABSTRACT TRUNCATED AT 250 WORDS)     

Exercise myocardial perfusion imaging in elderly patients

BACKGROUND: Exercise myocardial perfusion imaging (MPI) has significant value for risk stratification, but most patients studied have been middle-aged. In particular, the value of exercise MPI in elderly patients with interpretable electrocardiographic (ECG) stress test results has not been well defined. MEHODS AND RESULTS: Clinical, ECG stress test, MPI, and follow-up data for 626 outpatients aged 65 years or older with interpretable electrocardiograms undergoing symptom-limited exercise MPI between 1992 and 1996 were analyzed. Follow-up was 97% complete after 4.4 +/- 1.3 years. After exclusion of the 27 patients who underwent revascularization within 90 days of MPI, there were 361 men and 217 women, aged 70.7 +/- 4.4 years. By univariate analysis, male sex, increasing age, an abnormal rest ECG result, lower exercise tolerance and lower peak exercise heart rates, exercise ST-segment depression, left ventricular dilatation, and the number of ischemic regions predicted death or myocardial infarction. By multivariable modeling, only increasing patient age, male sex, limitation of exercise tolerance, and the number of ischemic segments by MPI were predictive of subsequent death or myocardial infarction. CONCLUSIONS: In elderly patients referred for exercise MPI, age, sex, exercise tolerance, and MPI ischemia provide significant prognostic information.     

Exercise cardiac function in young through elderly endurance trained women.

PURPOSE: To clarify the physiological reasons for the decline in aerobic power of endurance trained (ET) women with aging. METHODS: Blood volume, VO2max, and exercise cardiac function were examined in 23 ET women; six age 20-29 yr, six age 40-45 yr, six age 49-54 yr, and five age 58-63 yr. RESULTS: Blood volume was unchanged with aging. VO2max declined progressively at a rate of 0.51 mL x kg(-1) x min(-1) x yr(-1). During maximal exercise, there was an increase in total peripheral resistance (TPR) and a decrease in heart rate, stroke volume, and cardiac output with increasing age. At all ages, cardiac filling (diastole) was significantly faster than cardiac emptying (systole). Stroke volume did not plateau at a submaximal work rate but increased progressively to maximum. CONCLUSIONS: The decline in VO2max with age in ET women is due to decreases in maximal heart rate, stroke volume and cardiac output, and the primary advantage in the exercise cardiac performance of ET women of all ages is diastolic rather than systolic function.     

Exercise responses of elderly patients with diastolic versus systolic heart failure

PURPOSE: Little information is available regarding peak and submaximal exercise performance in elderly heart failure (HF) patients, particularly in those with diastolic dysfunction (DD). Therefore, the purpose of this investigation was to compare exercise responses of elderly patients with HF due to either systolic dysfunction (SD) or DD, to age-matched healthy volunteers (HV). METHODS: Patients with chronic HF > or = 60 yr (N = 119) due to SD (N = 60) or primary DD (N = 59) underwent a maximal cycle ergometry test with expired gas analysis and venous lactate measurement. Twenty-eight HV > or = 60 yr served as a control group. Anaerobic threshold was determined by gas analysis (ATVEN) and by plasma lactate rise (ATLAC). RESULTS: Peak oxygen consumption (VO(2peak)) was significantly (P < 0.001) reduced in both SD and DD patients (13 +/- 0.4 vs 14 +/- 0.4 ml x kg(-1) x min(-1), respectively) versus HV (20 +/- 0.6 ml x kg(-1) x min(-1)). Peak heart rate was reduced in patients versus HV (131 +/- 3 bpm vs 145 +/- 4, respectively; P < or = 0.01), but heart rate at a given submaximal work rate was significantly lower (P < or = 0.01) in HV than in SD and DD patients. ATVEN of 11.8 +/- 0.3 ml x kg(-1) x min(-1) for HV was significantly higher than SD (8.9 +/- 0.2) and DD (9.2 +/- 0.3). Peak lactate concentration was 6.6 +/- 0.6 mmol x kg(-1) x l(-1) in HV and was significantly reduced in both SD and DD HF patients. ATVEN correlated well with ATLAC in HV and in DD patients, but not in SD patients. CONCLUSIONS: Submaximal and peak exercise performance are markedly altered in elderly HF patients compared with age-matched HV but do not appear to be different between SD and DD patients.     

Exercise immunology: future directions for research related to athletes, nutrition, and the elderly

This article examines three questions related to exercise immunology: 1) Can exercise attenuate changes in the immune system related to aging? The few research papers available suggest that the answer may be "yes", but exercise training may have to be long-term and of sufficient volume to induce changes in body weight and fitness before any change in immunity can be expected in old age. 2) Is the athlete an immunocompromised host? For most athletes, probably not, although the answer may be 'yes' during certain periods when the athlete exceeds normal training limits or competes in endurance events. Most studies have reported that the immune systems of athletes and nonathletes in the resting state are more similar than disparate with the exception of natural killer cell activity which tends to be elevated in athletes. Infection risk may be more related to the acute changes in immunity that occur following heavy exercise, but this hypothesis has not been sufficiently studied. 3) Are nutrition supplements effective countermeasures to exercise-induced inflammation and immunosuppression? Except for carbohydrate, the answer at this time for all other nutrients studied is 'no'. While data from the vitamin and mineral studies have been negative, and those involving glutamine conflicting, several investigations indicate that carbohydrate compared to placebo ingestion is associated with attenuated hormonal and immune responses.     

Exercise myocardial perfusion scintigraphy is useful for evaluating myocardial ischemia even in the elderly

Pharmacologic stress testing is recommended to elderly patients as a valuable alternative to exercise testing. We examined whether exercise testing is as useful for evaluating myocardial ischemia in the elderly as in the young. The consecutive 1,508 patients who underwent exercise 201Tl single-photon emission computed tomography (SPECT) were divided into six age groups: 6-29 years (n = 56), 30-44 (n = 143), 45-54 (n = 311), 55-64 (n = 498), 65-74 (n = 402), and 75-88 (n = 98). Both heart rate and rate-pressure product at peak exercise were significantly lower in patients aged 75-88 than in the other five groups. The frequency of ischemic ST depression was higher in patients aged 75-88 than in those aged 6-74, although the difference was not significant. Moreover, the frequency of 201Tl transient defect was significantly higher in patients aged 75-88 than in those aged 6-74. On the other hand, the sensitivity of ischemic ST depression for 201Tl transient defect was similar among the six groups, but the specificity was significantly lower in patients aged 75-88 than in those aged 6-74. In conclusion, exercise 201Tl SPECT is useful for evaluating myocardial ischemia even in the elderly, but exercise electrocardiography has limitations such as lower specificity in the elderly than 201Tl SPECT.     

Exercise and the asthmatic

Physical exercise is not hazardous to asthmatics. Some asthmatics may benefit from physical training, and almost all asthmatics can perform any kind of physical exercise. Free running was earlier thought to induce more asthma than swimming, for example; however, when ventilation is identical during running and swimming, the exercise-induced asthma will also be the same. Hyperventilation alone is as good as physical exercise to induce exercise-induced asthma. If the physical exercise provokes an asthmatic attack, this is most often easily reversed by inhaled beta 2-agonists. Pretreatment of exercise-induced asthma is most efficient by inhaled beta 2-agonist; orally dosed beta 2-agonist is not as efficient as inhaled beta 2-agonist in the pretreatment of exercise-induced asthma. Inhaled sodium cromoglycate diminishes exercise-induced asthma, and the effect seems to be better in children than in adults. Inhaled steroids have no immediate effect on exercise-induced asthma, but long term treatment with steroids diminishes exercise-induced asthma. The pathogenesis of exercise-induced asthma remains obscure. If the water content is low in the inhaled air, e.g. in cold air, the changes in ventilatory capacity following exercise. will be greater than when the exercise is performed while inhaling hot air with high humidity. Almost all asthmatics present changes in the ventilatory capacity following exercise. Seasonal changes in exercise-induced asthma are only present in asthmatics with seasonal allergies, e.g. pollen allergy. No diurnal variation is found in exercise-induced asthma. Asthmatics can do any form of physical exercise. Almost all asthmatics can prevent major changes in ventilatory capacity by pretreatment of exercise-induced asthma or be treated for exercise-induced asthma during the physical activity so that they will not suffer from asthma while performing physical exercise. Asthmatics who have been successfully treated for exercise-induced asthma can do physical exercise at the same level as non-asthmatics. Asthmatic children in particular should be encouraged to perform any sport they like, as the physiological and psychological effects may be beneficial to them. It is concluded that almost all asthmatics have exercise-induced asthma, and that physical training may be beneficial. Exercise-induced asthma is best treated and pretreated by inhalation of beta 2-agonists.     

Exercise heat acclimation and post-exercise hot water immersion improve resting and exercise responses to heat stress in the elderly

ObjectivesTo investigate the efficacy of heat acclimation (HA) in the young (Y_EX) and elderly (E_EX) following exercise-HA, and the elderly utilising post-exercise hot water immersion HA (E_HWI).DesignCross-sectional study.MethodTwenty-six participants (Y_EX: n = 11 aged 22 ± 2 years, E_EX: n = 8 aged 68 ± 3 years, E_HWI: n = 7 aged 73 ± 3 years) completed two pre-/post-tests, separated by five intervention days. Y_EX and E_EX exercised in hot conditions to raise rectal temperature (T_rec) ≥38.5 °C within 60 min, with this increase maintained for a further 60 min. E_HWI completed 30 min of cycling in temperate conditions, then 30 min of HWI (40 °C), followed by 30 min seated blanket wrap. Pre- and post-testing comprised 30 min rest, followed by 30 min of cycling exercise (3.5 W·kg⁻¹ Ḣ_prod), and a six-minute walk test (6MWT), all in 35 °C, 50% RH.ResultsThe HA protocols did not elicit different mean heart rate (HR), T_rec, and duration T_rec ≥ 38.5 °C (p > 0.05) between Y_EX, E_EX, and E_HWI groups. Resting T_rec, peak skin temperature, systolic and mean arterial pressure, perceived exertion and thermal sensation decreased, and 6MWT distance increased pre- to post-HA (p < 0.05), with no difference between groups. Y_EX also demonstrated a reduction in resting HR (p < 0.05). No change was observed in peak T_rec or HR, vascular conductance, sweat rate, or thermal comfort in any group (p > 0.05).ConclusionsIrrespective of age or intervention, HA induced thermoregulatory, perceptual and exercise performance improvements. Both exercise-HA (E_EX), and post-exercise HWI (E_HWI) are considered viable interventions to prepare the elderly for heat stress.     

Exercise and the immune system

Exercise has a variable effect on the immune system. The underlying reasons for this variability are multifactorial and include infectious, neuroedocrine, and metabolic factors, with nutritional status of the athlete and the training load playing a role. Environmental factors such as living quarters, travel requirements, and the type of sport (team versus individual) also contribute to infectious risk. Regarding the direct effect of exercise on the immune system, moderate exercise seems to exert a protective effect, whereas repeated bouts of strenuous exercise can result in immune dysfunction. Understanding the relationship between exercise and infectious disease has important potential implications for public health and for clinicians caring for athletes and athletic teams.     

Exercise and the immune response

A growing number of reports have become available which implicate infectious disease with reduced performance in athletes. The immune system consists of both nonspecific and specific components geared to control infections. Adaptive immunity functions through both antibody-mediated and cell-mediated compartments to establish and maintain long term immunity to infectious agents. Evidence is accumulating to support the view that physical exercise can lead to modification of the cells of the immune system. However, studies have often not been well designed to control exercise protocols when examining the effects of exercise on the immune system. Large numbers of peripheral blood lymphocytes are mobilised with exercise and in vitro tests indicate that temporarily these cells may not be capable of responding normally to mitogens. These reactions appear to be influenced by hormones to some degree and there are reports that the cells of the immune system are extremely active biochemically and may depend on products from muscles to maintain their activity. Specific populations within the circulating leucocyte pool vary significantly with exercise and there is some evidence that the T4/T8 lymphocyte ratio may become significantly reduced. This reduction in ratio may be related to the variable responses to T and B cell mitogens recorded in vitro which overall suggests that a temporary immune suppression may exist following certain training or performance schedules. It is argued that this may lead to a temporary susceptibility to infection and could result from overtraining.     

Exercise and the Cardiovascular System

Whether regular endurance exercise will increase life span has not been conclusively proved, but as one panelist says, ‘If you want to take a gamble, it's a good one.’     

Exercise and Osteoporosis-Related Fractures: Perspectives and Recommendations of the Sports and Exercise Scientist

Abstract

Osteoporosis-related fractures represent a major health concern, particularly in elderly populations. Direct and indirect costs (amounting to nearly $17 billion in 2005), increased morbidity, and loss of independence place substantial burden on the health care system. Observational studies have shown that a physically active lifestyle is associated with a 30% to 50% decrease in vertebral or hip fractures, and a recent meta-analysis that determined the effects of exercise on fracture incidence further confirmed these results. However, because no randomized controlled exercise trials have selected fractures as a primary endpoint, causality between a sedentary lifestyle and fractures may be potentially confounded by participants' poor health status. With regard to fall reduction and bone strength as the main surrogates for fracture risk, many randomized controlled trials and corresponding meta-analyses have reported significant positive outcomes. Interestingly, no study that has assessed fall-related injuries has focused specifically on interventions that aimed to reduce fall impact. There is ongoing debate as to which factor, osteoporosis or falls, is more important for fracture prevention. This may be dependent on the region prone to fracture and the subjects' health status. In randomized controlled trials on exercise, the type, mode, and composition of exercise parameters are predictors of study outcome. Unfortunately, many exercise trials on fall prevention have not adequately described the exercise protocol used, which makes it difficult to determine which fall prevention protocol was most effective. A recent meta-analysis recommended Tai Chi and/or a mix of balance and resistance exercises for fall prevention. More sophisticated protocols are required to impact bone strength. Corresponding state-of-the-art protocols have focused on periodized high-impact/high-intensity resistance protocols performed at least twice per week. In the frail elderly, high-frequency/high-cycle number exercise programs with low-to-moderate strain intensity may also positively affect bone strength.     

Exercise and the hypertensive athlete.

Exercise helps to manage high blood pressure in most circumstances and should be encouraged in both hypertensive athletes and active individuals with this disease. Many physiologic mechanisms have been proposed that explain this benefit. Presently, it appears from both human and animal studies that exercise of moderate intensity may be optimal for control of high blood pressure. Exercise testing for the future prediction of hypertension is an intriguing concept, but more data needs to be gathered before screening can be recommended.     

Isometric Exercise and the Cardiovascular System

In brief: There is little evidence that isometric exercise benefits the cardiovascular system, and many physicians believe that it imposes undue demands on the myocardium, so they prohibit such exercises for middle-aged or coronary disease patients. This review article examines the validity of this conclusion by summarizing the effects of isometric exercise on heart rate, blood pressure, myocardial demand, cardiac output, peripheral blood flow, and left ventricular function. Dr. Fardy concludes that isometric exercise is less hazardous than has been presumed and says guidelines should be established according to each patient's history.