The Cardiorespiratory Fitness - Example

PHYSICAL ACTIVITY: According to two recent studies carried out in Britain (47-49), it is evident that the prevalence of CHD is approximately half in physically active men in the early old and middle age as compared to the CHD prevalence in sedentary men. In addition, a follow up study carried out on 9376 male British civil servants of 45 to 64 years of age for a period of 9years indicated that at the beginning of the study the men who were actively involved in sports had less than half the fatal and non-fatal disease compared to the sedentary men (Morris et al, 47). Consequently, Wannamethee and Sharper (48, 49) indicated from the 9 year follow up British heart study carried out on the 7,735 male participants, aged between 40-59 years, that physical activity helped in reducing heart attacks as well as stroke in men suffering from ischemic heart disease as well as those who are not. CRF & CVD: It is evident from a number of studies that in asymptomatic populations exercise capacity is of importance to survival (Paffenberger et al 1993 & Blair et al 1995). The intensity of the link between the cardiovascular disease mortality as well as cardio-respiratory fitness as compared to other risk factors of CHD was looked at in the Aerobics Center Longitudinal study, Blair et al 1996). For a period of 8 years a follow up of over 33000 subjects was done. It was apparent from the results that as compared to the low fit people with no predictors, the high fit people with several risks of hypertension, smoking and hyperlipidemia had a low mortality of 64%. Further, it was emphasized by the results of a cross section done on this particular study population in 1998. The study indicated that improving to moderate level from a low cardio-respiratory fitness was linked to the reduction of all- cause mortality by 42%, (Farrell et al, 1998). In addition, Farrell and his colleagues confirmed that sedentary lifestyle was a major predictor of the cardiovascular disease. On the other hand, an investigation on the link between the overall cardiovascular disease non-CVD- related as well as CVD –related and cardiovascular fitness was carried out, Laukkannen et al. The results indicated that on a baseline, in eastern Finland communities and Kuopio there are 1294 men without the CVD, cancer or pulmonary disease. In addition the results pointed out that during a 10.7 years average follow up on 124 subjects, there were 82 were non-CVD related deaths and 42 CVD related deaths. In conclusion the study depicted that there was a very strong inverse association between cardiorespiratory fitness with the overall non-CVD related as well as CVD related mortality. However, in their study, only a Vo2 max at baseline single measurement was used, (Laukanen et al, 2001). Preferably, in order to examine the impact over time, there is need to repeat the measurement of cardiovascular fitness. Blair et al., (1996) carried out a study on 3,120 women and 10, 224 men who went through a maximal exercise test. Based on the MET level attained, these people were then subdivided into five fitness groupings. From an 8 years follow up, the attuned relationship between the cardiovascular, exercise capacity as well as the all cause death rate inverse for both men and women was graded. When changing from the one fit ( < 6Maximal Exercise Tests) to the other of 7 maximal exercise tests, there occurred a significant decrease in mortality risk. The decrease continued specially with the higher fitness levels and it was noted that the decline stopped at in approximation at 9 METs for women and 10 METs for men. It is evident from the findings that at a moderate fitness level which is attained through taking a half to one hour brisk walk per day, health benefits can be realized. Consequently, similar results were realized by researchers who assessed the effects of fitness within groups possessing particular risk factors for instance smoking, diabetes or hypertension Mortality: It is apparent from a past meta-analysis that for patients with myocardial infarction (MI), exercise and CR contributed to the low cardiovascular mortality, (Oldridge, et al 1988 and O’Connor et al 1989). In a more recent review by Cochrane of 7600 Cardio respiratory patients highlighted that the cardiovascular mortality decreased by 31% and the total mortality by 26% as result of the exercise intervention’ (Joliffe, et al., 2001). The studies were mainly carried out on the middle aged group ( 65 years and below) and it was found out that in men the applicability of the exercise was less as compared to the whole population. The studies nevertheless were performed before the extensive application of coronary stent placement, thrombolytic therapy and aggressive drug therapy, therefore signifying the effect that exercise offered in declining mortality rather than the numerous drug interferences that are lessening mortality currently. Apparent from the review is that exercise training was the main component that focused on fitness training a main means of physical activity intercession. An increase of functional capacity is the sole goal for fitness training. This is because they have been found to have an association with all-cause as well as cardiac mortality and morbidity, (Kavanagh et al, 2002) During the cardiac rehabilitation, first three decades, the most paramount subject was to reduce cardiac mortality as well as morbidity. There was so little study sample in many studies that demonstrated clearly the effects of mortality and morbidity 25, 44-46. This is because most of these researches mainly focused on low risk patients 47. The study design was also found to be a problem. It was very difficult to get a controlled group using the randomized way and hence a number of uncontrolled trials were carried out, 48. Certain studies employed surrogate group control. For instance a control group randomized to a restricted exercise training program that is assumed not to have any impacts. Patients from hospitals especially remote were also used for matched controls 51, random allocation 35,52,53 as well as control 50. The only study that employed randomization only assessed a very small population44. Despite these problems, several of these studies recorded a decrease in the cardiac mortality as well as morbidity. From a 5 year follow up by Hedback it was evident that there was a remarkable decline in cardiac events rate (39.5% versus 53.2%) and non-fatal myocardial infarctions (17.3% versus 33.3%) right after rehabilitation50. As a result, for a period of five years, cardiac mortality did not experience any decline. After a follow up study of 10 years, it was realized that the effects on total cardiac mortality were (36.7% vs. 48.1%) and those on morbidity,( 42.2% vs. 57.6%). Other investigators verified the significant impacts on cardiac mortality 35, 53, 54 as well as the impacts on cardiac morbidity. O’Connor and Oldridge carried out a meta-analysis of three years on over 20 randomized groups and it was realized that after the myocardial infarction, cardiac rehabilitation decreased remarkably with approximately 20% both on the overall as well as the cardiovascular mortality. Also evident from these analyses, the decline of non-fatal reinfarction hardly reached statistical importance. According to studies, the above named studies occurred from the seventies through to early eighties. Ever since, there have been a massive increase in therapeutic options in cardiology, for instance coronary angioplasty, thrombolysis, lipid lowering drugs, Angiotensin Converting Enzyme Inhibitors, stenting, implantable cardiac defibrillator, and besides prognosis has developed significantly. The extents to which this information can still be used remains unknown and it necessitates re-establishment. In the contemporary, studying mortality and morbidity is quite a task. This is because such a study requires a big sample size as evidenced by the reduced rate as well as mortality after myocardial infarction. As per the calculations by Greenland, 4000 participants at least are required to attain the statistical significance 47. Another possible approach is to carry out a study on the patients who have a higher risk for instance the patients experiencing congestive heart failure. In a recent research, Belardinelli pointed out that after cardiac rehabilitation, there was a remarkable decline of hospital admissions and mortality in these patients for heart failure 57. According to O’Connor and colleagues (1989), in a meta-analysis of CR, no difference was noted in cardiovascular effects between those studies that involved other hygienic interferences confirming the value of the exercise constituent and the once that involved exercise only (Thompson, 2005). It is apparent according to (OConnor et al., 1989), that CR programs which have aerobic exercise training for the patients after the occurrence of an acute myocardial infarction betters the quality of life, lessen coronary risk factors, improve exercise capacity, lessens following hospitalization bills as well as major coronary artery disease effects such as sudden death, all-cause mortality as well as fatal myocardial infarction. In the near past, a rationalized meta-analysis was carried out by Taylor et al. (2004), on the rehabilitation trials which exist among the patients suffering from coronary heart disease. In total 48 trials with 8940 patients met their inclusion standards (Taylor et al, 2004). Cardiac rehabilitation was linked to decreased cardiovascular as well all- cause mortality as in comparison to usual care (Taylor et al, 2004). Moreover the active involvement in the CR program was linked to a significant decrease in systolic blood pressure, cholesterol as well as triglycerides (Taylor et al, 2004). No differences were noted between the usual care groups and rehabilitation in the revascularization rates or non-fatalreinfarction (Taylor et al, 2004) Measuring vo2 peak In order to evaluate the exact maximum VO 2 in CHD, there is need for patients to undertake an ultimate exercise test and at the same time ensuring that their respiratory gases are measured. The Bruce treadmill protocol is the most frequently used test. It is an incline and progressive speed test which is done on a treadmill. However, according to ACSM (2009), other protocols including the ramp or the cycle ergometer protocol might take priority but this depends with the assessment needed. Bruce, Kusumi & Hosmer (1973), cited in Milani Lavie & Spiva (1995), put forth that when maximum VO 2 is not measured straightforwardly nevertheless, it is usually estimated by the use of a regression equation which links treadmill performance to the uptake of oxygen and this is generally dictated by workload. This provides a maximum VO 2 that is habitually population definite and has a probability of overestimating maximum VO 2 in CHD patients. Indeed, Milani et al., (1995) performed a maximum treadmill test on fifty patients before commencing cardiac rehabilitation, and repeated this later after a twelve week period, after the end of the exercise course. So as to attain this, two evaluations were reported, the projected developments achieved by the employment of ACSM calculations and the real VO 2 development by gas air assessment, founded on the workload and the speed on the treadmill. The outcomes indicated a 43 percent difference between the figures, and the projected METS were higher. It was assumed that the variations were as a result of test familiarity and an enhanced work competence brought about by exercise on the treadmill during the cardiac rehabilitation course. Lavie and Milani (2000), prolonged this study to a group of CR patients aged more than 70 years and less than 50 years. These scholars employed a ramping treadmill procedure to evaluate 183 patients before and after cardiac rehabilitation, matching the influences of intervention on measured and projected METS, through the application of ACSM formula (ACSM, 2009). The results revealed that the elderly groups’ measured VO 2 amplified by merely 13 percent whilst the projected aerobic aptitude boosted by 32 percent. Alternatively, the younger group revealed an increment on the projected aerobic capacity (44 percent) related with the real growth (14 percent). Nevertheless, this investigation was limited by the deficiency of non-exercise groups and besides, the research indicated the imprecisions in the ACM equation when calculated in a ramping procedure (a non-stable state exercise). Generally, there are numerous researches estimate VO2 that are based on performance however, just a few measure it, they are better nonetheless expansive. Treadmill: Walking on a treadmill particularly for the first time may be a very discouraging practice and much tussles to take control of their pace. Numerous studies (Murray et al, 1985; Alton et al, 1998) revealed that the step length is usually smaller while the pace is greater when treadmill walking is matched to floor walking. Treadmill: pros and cons Regrettably, studies have indicated that such tests are hard for clinicians to carry out. This is linked to either unavailability of the equipment or unaffordability of the tests both to the clinicians and the patients. Apparently, the gold standard used for measuring Maximum VO 2 has a tendency to becoming much complicated, consumes more time and in addition necessitates various practice sessions prior to commencing the test. As a result, sometimes, clinicians evaluate the functional capability of the patients by employing safer, cheaper, and simpler equipment, for instance functional walking tests. Relationship FC and mortality The best predictor of all mortality, according to Myers et al (2002) for cardiac patients is the functional capacity when it is measured against all the rest cardiovascular risk factors. According to Franklin et al., (2003), for a six year follow up, each 1 MET upsurge in functional capability leads to a 10 percent decline in mortality. A study was carried out to investigate if a measure of functional capacity would be applicable as a independent predictor of people 60 years of age Sui et al (2007). As indicated in a 13.6 year follow up, the subjects who have a low functional capacity that reached 5.8±0.7 METS were highly linked to higher risk of CVD- related mortality as well as all-cause when compared to the once with high (10.6±1.7 METS or moderate (7.9±0.9) METS functional capacity. Hence, functional capacity can be an independent predictor of mortality in terms of cardiovascular capacity. In addition other health benefits are linked to it as well. Myers et al (2000) was in agreement with Sui et al (2007), in his study. He verified that a less than five MET exercise capacity resulted to two times the risk of death when compared to a less than 8 MET capacity. Therefore, there exists a ‘dosage response’ association between the all-cause mortality and exercise capacity which are independent other risk factors. A major problem of the research is that it hardly considered the cause of death, and hence it remains unclear whether the deaths could be CVD related. Moreover, the non-CVD subjects were remarkably 6 years younger than the CVD subjects. From this it is apparent that other causes of death become more significant as age increases. As a result, it is clinically suitable to have the capacity of measuring such an essential prognostic factor in an effective and dependable way. In regularly clinical practice, effective and dependable prognostic stratification patients can assist in therapeutic decision making and lifestyle change. The capacity to accurately measure functional capacity is an essential part of diagnostic evaluation in clinical populations. Functional capacity is very significant and as a result, we require good methods testing it. 6MWT prognosis: Among the very first large-scale ( n=898) researches that highlighted that 6-MWT was applicable as a prognostic marker in the patients experiencing HF is the Left Ventricular Dysfunction Study (Bittner et al., 1993). It is evident that the distance walked within the 6-MWT linked remarkably with one year mortality. In addition the patients who attained MSWD score of < 300m were at high risks (OR=1.77, 95% CI=1.38 – 2.26) of being hospitalized or dying in a period of one year compared to the patients who attained greater than 300m. Roul et al. (1998) established that inferior 6MWD (≤300 m) might foretell the morbidity and mortality among patients diagnosed with moderate-to-mild HF (NYHA class II or III). An assessment was done on 121 patients of over 1.53(±0.98) years while applying a symptom-limited argometer test with a 6-MWT and VO2 max. The VO2 max significantly correlated with the 6MWD from the cycle ergometer test. Applying a distance of 300m as a threshold, illustrated the 6-MWT as an essential prognostic indicator for morbidity and mortality in this population. They illustrated that the proportion of short-term, considered to be 500 days, event-free endurances were about 75 per cent for the patients walking between 450m and 370, and about 50 per cent for the patients walking ≤370 m in the 6-MWT. In the same way, Rostagno et al. (2003) assessed if the 6-MWT could be applied as a consistent and simple tool for the prediction of cardiac death among patients having moderate to mild HF (n=214). In a more recent study by Arslan et al., (2007), on stable mild-to moderate HF patients, similar results were realized. The death risk was found to be high in the patients who had ≤0.30% left ventricular ejection fraction ( LVEF) as well as the patients those who had walked ≤300 m in the 6-MWT. According to Arslan et al., (2007), several limitations were noted. They include losing a remarkable proportion (30%) of the first patients in the follow up, small sample size and a short timeframe to carry out the study. However in spite of the limitations, the 6-MWT was seen to be a consistent and self-sufficient predictor of cardiac death (Arslan et al., 2007). 6MWT and SWT: It is apparent that several studies have been carried out to determine if the distance walked on SWT can be linked to traditional for instance VO2 max values. According to the results, the distance walked in SWT was found to be highly linked to VO2 max which is as a result of treadmill protocol, (Singh et al., 1994; Fowler et al., 2005). The SWT and the 6-MWT are often applied in CR, since a knowledge gap surrounds potential clinical and non-clinical factors, which influence test performance; as there are no standard normative values of functional capability for the walking tests. The research gap provides an opportunity to further investigate into this area. Summary Giudlines: It is apparent that service provision and cardiac rehabilitation differs across nations as a result of disparities in culture, socioeconomic status and demographic features (Davidson et al., 2010). Nonetheless, all state and global cardiac rehabilitation committee usually support attendance at cardiac rehabilitation programmes and in addition, they have put in place their guiding principles around a general set of objectives. Termination criteria • Feeling excessively breathless to carry on any kind of anginal symptoms • Feeling faint or dizzy • Leg pain which limits more exercise • Attained degree of observed exertion is greater than 15 (Borg Scale128) (see section 3.7). • Attained heart rate is greater than =85 percent forecast (discoverd by audible upper alarm limit). • Unable to meet up speed necessities of the test- at the sound of a bleep, subject more than half a meter from the cone Validity of the ISWT Various studies have indicated that the SWT are a true measure of CR capability when matched with the gold standard measurement. Fowler et al., (2005) has revealed the fact that ISWT is an effective outcome measure for CR after a practice walk that was based on related researches which indicated a strong association (r=0.87, with confidence intervals of 95 percent), between the length covered on the test in metres and straightforwardly obtained VO2max employing expired air evaluation in a group of 31CABG patients. A regression plot was sketched for VO2 and MDW peak in ml kg min, indicating a 95 percent Cl, which resulted to the following regression equation: 7.81 + (0.03x ISWT distance (m)). Another correlation between the distance covered (r=0.95) and the VO2 peak in a group of patients suffering from cystic fibrosis in a regulated ISWT which added three extra levels. Green et al (2001) established a strong important relationship (p=0.05, r=83 7) between MDW and peak VO2 from the treadmill while measured when calculated using the Cosmed K4b2 portable breath by breath evaluator among the patients diagnosed with congestive heart failure. This was in agreement with the work of keel, chambers Francis, Edwards and Stables (1998) which confirmed a relationship of r=0.84 in patients suffering from heart failure. Nevertheless, according to Ades et al, (2006), when direct actions of VO2 have not been carried out, researchers have yet tried to produce normative values of VO2 for those patients who are beginning cardiac rehabilitation. Ades et al, (2006), also recommend that direct values of maximum VO2 must be employed where applicable instead of estimated values. So what is the reliability of the sub-maximum tests at providing precise information to the practitioner regarding VO2 on entering CR and for depicting the post intervention results? Reliability According to Singh et al. (1992), the reliability of ISWT has been proved to be reliable following a one practice walk among the COPD patients. To acquire precise results from the SWT, there is some level of doubt as to whether some walking practice is required. Arnott (1997) noted reproducible outcomes in a group of CAGB patients, without having to carry out a practice walk. However, between the first and second tests, an increase of 4.7 per cent was noted, but these results were insignificant. Green et al. (2001) identified no significant distinctions in the test-re-test distance attained by seven patients with heart failures (513m vs. 517m) though the fact that the patients were accustomed to the ISWT a week before the testing was not mentioned. According to Fowler, et al. (2005) there is no major differences exist between the first and the preceding tests among the CABG participants, hence no practice was needed. However, there existed a difference between the first test and the second test of the 42 metres as opposed to difference between the second and third test which was only eight. The first test was accomplished a week before the other two tests, and the highest heart rate on all tests was not considerably different. However as noted, the coefficient repeatability between the second and third test was only 21 metres, while this was reorder to be 122metres between the first and second tests. Therefore, the performance difference between the second and third tests could be replicated 95 per cent of the time, and expected to be about two shuttle lengths. Lately, a research was conducted by Jolly, Taylor, Lip and Sing involving 353 partcipants with CR from the Birmingham Rehabilitation Uptake Study (BRUM) to assess whether practice wa required in order to walk. According to the findings, there existed a significant difference (p=0001) between test one and test two of approximately 29.5 metres, which had no impact on the heart rate, and it was therefore concluded that the distance variations were due to familiarity and not motivation indicating a practice walk. This represented a 10 per cent familiarity. Even as this appears to be insightful and interesting, the study illustrates the significance of involving heart rate within the assessment and results of the test, particularly when a practice walk cannot be conducted. Most of the United Kingdom’s CR programmes are resource inadequate and thus the time required for testing the patients may not be available since only 16 per cent of the programmes can access the suggested physiotherapy time (Audit BHF, BACR 2008). In addition, contemporary guidance from the BRUM study requires that practice test be conducted 30 minutes before the actual test is carried out, adding another question regarding the reliability of the test in periods of more than 24 hours. Turning Time: Turning is often applied in daily activities, where for instance, two steps are needed for to make ten steps. Turning is defined as a complex movement where the accomplice is required to slow down the forward motion and choose one from the two strategies, turn the body in a lateral angle, apply the forward leg as an axis in the turning direction and make the step in that direction while accelerating (Hase and Stein 1999; Taylor et al, 2005). During the slowing down process, the foot that is rooted on the ground at the front side of the body directs the timing of the muscle activities in order to create the braking force. The walking speed before a turn is made can be decreased using different deceleration mechanisms, considering the timing taken in the step cycle and the type of task undertaken (Yang and Winter 1985; Hase and Stein 1998, 1999). Functional balance and mobility interact to attain daily movements, such as standing, turning, walking and sitting. In addition, they interact with various variables such as speed; the number of steps, the turning time and type of turning that are required in order to make a full turn (Hase and Stein 1999; Demura and Uchiyama 2007). According to Gorgon et al. (2007) healthy people having few or no chronic conditions like diabetes, CHD, chronic obtrusive pulmonary disease and HF, are likely to have an improved mobility. Such people are considered to carry out turning tasks more easily compared to those considered to have a higher number of persistent complications. The old cardiac patients having several pathologies for instance, are considered to have a poor mobility as a result of attenuated practical locomotion system functioning. Old age is often associated with lessened functional mobility. Gait characteristics transform to minimize the likelihood of falling. Aged people often decrease the length of the step, cadence and gait speed, while increasing the number of steps applied during the process of turning, an the turning time (Laufer 2005; Demura and Uchiyama 2007). Imms and Edholm (1981) highlight that the time covered while turning can be applied as an index of determining mobility. 70 participants with ages between 60 and 90 years diagnosed with different pathologies such as post-myocardial infraction and post stroke were assessed by engaging them in diverse tasks. The time used while turning on a walkway illustrated a high correspondence to their speed of walking (Pearson‟s r=-0.824; p Read More