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Guest "opinion and challenge" blog via Richard J Godfrey PhD FACSM FBASES Centre for Sports Medicine and Human Performance, School of Sport and Education, Brunel University, Middlesex, England.
Patients who have heart disease or have had a heart event should contact their doctor or local British Association Cardiac Rehabilitation (BACPR) team for advice on physical activity and exercise. For patients in countries other than the UK, patients should approach their health care provider and ask about available support for exercise in heart disease programmes.
Myocardial damage can lead to heart failure and ultimately the requirement for a heart transplant. The economic, personal, familial and societal costs are high and growing each year as a result of increased survival following MI. The healthcare cost, for example, of the 146 000 heart attacks in the UK each year is estimated at £350 billion (www.cardiac matters.co.uk). For decades the universal belief amongst clinicians was that, once damaged, the mammalian heart developed scar tissue which was immutable and permanent; a logical conclusion given the adult heart is a post-mitotic organ withdrawn from the cell cycle.
In recent years however, this view has been challenged, [1,2] supported by a rash of studies examining the impact of high intensity exercise on the post-MI heart being carried out, predominantly, in rodents. Numerous studies have demonstrated the benefits of high intensity exercise for cardiac function with increases in cardiomyocyte mitochondrial biogenesis and hence improved myocardial oxygen cost (requiring less oxygen for routine function)  and boosting maximal aerobic power (VO2max) , which is inversely correlated with all-cause morbidity and mortality. [5,6]
A recent study was cited in the press following publication in the European Heart Journal. This research  demonstrated that vigorous exercise in mice resulted in the activation of 60% of cardiac stem cells and elicited a comment from Prof Jeremy Pearson, Associate Medical Director of the British Heart Foundation. In this he recognised for the first time that adult hearts may be able to produce new myocyctes from previously inactive stem cells but suggested that a lot more research was needed before this could be used as part of treatment for human patients (www.telegraph.co.uk/health/healthnews/9651682/Exercise-could-repair-heart-damage.html).
Currently, there is a paucity of research findings examining the cardiac effects of high intensity exercise in humans. One notable exception is the SMARTEX-HF study in Norway  which has recruited 200 patients, with a range of ‘conditions’ from CHD and diabetes to heart failure and old age. Individuals who are part of this cohort have undertaken 12 weeks of supervised, high-intensity interval training with heart rate reaching greater than 90% of maximum in each session and with assessments made pre, at 12 weeks and at 1-year follow-up. Unofficially, findings are good so far with improvements in function and quality of life and with no adverse incidents, but full findings are not likely to be published until the Autumn of 2014 and assessments will not include cardiac MRI and so will not examine any signs of cardiac repair.
In contrast, a case study was recently reported in BMJ Case Reports  and cites the case of a 50 yr old male who sustained an MI following the appearance of right coronary artery thrombosis, the consequence of an acquired coagulopathy. The individual was a lifelong vigorous exerciser and, following the MI, undertook 60 weeks of high intensity interval training (6-10 intervals of 1 min duration with 1:1 work:rest ratio), 3 times per week, on an exercise bike, with each interval eliciting >90% of maximum heart rate. Cardiac MRI scans were carried out at 14 and 60 weeks and compared with a scan obtained 14 months after the original MI, when remodelling can be considered complete, and at that time the extent of the scar was 16.3% of myocardial mass. At 14 weeks scar tissue was reduced to 9.6% and at 60 weeks to 8.5%. Hence, high intensity exercise appeared to result in a decrease in myocardial scar tissue of almost 50%. Exercise has never before been demonstrated to reduce scar tissue in any animal model, never mind in humans.
The paucity of research examining the impact of high intensity exercise in the post-MI hearts of humans should not sway us from believing that high intensity interval training may provide a mine of cheap alternative therapy in a landscape where long-term health care and ‘conventional’ treatment is very expensive.
Improved drug therapy will take considerable time and cost to develop. Relative to drugs, exercise is very cheap, has vast and growing reservoirs of evidence to support its efficacy and is available now.
For many clinicians the beneficial effects of high intensity exercise will be seen as a paradox because it is their current perception that implementation of this modality increases the risk of coronary events and deaths and that moderate intensity exercise is as hard as it should get. However, it is worth noting that there is no empirical evidence, even from clinical populations, that high intensity exercise constitutes a greater risk than low or moderate intensity exercise and there is a rapidly growing body of evidence for the efficacy of high intensity exercise to prevent or reverse a number of diseased states [10,11,12].
The suggestion is not the immediate wholesale adoption of high intensity interval exercise for all cardiac patients nor for the exclusion of all other intensities of exercise. Cardiac rehab in this country already allows for moderate intensity exercise and even vigorous exercise occasionally for those patients who are able and willing. Unfortunately, the image of someone undertaking high intensity exercise is of someone showing all the visible signs of working very hard indeed. That is, breathing very hard, sweating excessively and, perhaps even, being in pain whilst exercising. This is a misperception as individuals should work relatively hard i.e. hard relative to their current capacity. For example for people over 65 who have sustained an MI I am NOT suggesting running 6 x 800m flat-out on the athletics track or similar. I am recommending a high RELATIVE intensity of exercise. For an older, post-MI individual this might mean walking 30m in 60s (or slower) and then walking 10m in 60s and alternating this for 5-10 repetitions.
The point is to elevate the individual’s heart rate to above 85% of their own predicted maximum. I suggest that it is these, relative, hard efforts that act as a stimulus for positive / ‘reverse remodelling’ of the damaged myocardium. (Note: the term ‘remodelling’ is generally thought of as a negative re-ultrastructing and is the consequence of low or no physical activity in the immediate period post-MI). So, the suggestion is that: it is the hard efforts which stimulate repair of the heart. This type of training should be the primary focus in the immediate post MI period to specifically stimulate cardiac repair and so should probably be implemented 3 times per week for around 16 weeks, although in truth the research has not yet been done to confirm that. Of course, moderate intensity exercise of around 30 min per day can be used on the remaining days of the week. However, once repair is optimal the exercise routine should change. So, appropriate exercise is prescribed according to the needs of the patient at that given time. Exercise is always needed, and should of course be part of everyone’s lifestyle, but the emphasis does and should change over time according to circumstance and be tailored to issues of capability, illness, injury, disease and prior PA.
A growing volume of evidence suggests that the majority in developed societies would benefit, in the short, medium and long term, from regular high intensity interval training.
However, further extensive research is required to examine many aspects; from its safety, efficacy and optimisation to issues of behaviour change required to improve adoption, to examine how to improve adherence and on how best to address practical implementation.
1. Sun Y, Kiani MF, Postlethwaite AE, Weber KT (2002). Infarct scar as living tissue. Basic Res Cardiol 97: 343-347
2. Bergmann O, Bhardwaj RD, Bernard S, Zdunek S, Barnabe-Heider F, Walsh S, Zupicich J, Alkass K, Buchholz BA, Druid H, Jovinge S, Frisen J. (2009) Evidence for cardiomyocyte renewal in humans. Science 324:98-102
3. Molmen-Hansen HE, Stolen T, Tjona AE, Aamot IL, Ekeberg IS, Tyldum GA, Wisløff U, Ingul CB, Støylen A (2011). Aerobic interval training reduces blood pressure and improves myocardial function in hypertensive patients. Cardiovasc Prev Rehab epub- DOI: 10.1177/1741826711400512 ejcpr.sage.com
4, Wisløff U, Støylen A, Loennechen JP, Bruvold M, Rognmo Ø, Haram PM, Tjonna AE, Helgerud J, Slørdahl SA, Lee SJ, Videm V, Bye A, Smith GL, Najjar SM, Ellingsen Ø, Skjaerpe T. (2007). Superior cardiovascular effect of aerobic interval training versus moderate continuous training in heart failure patients. Circulation 115: 3086-3094
5. Blair SN, Kohl HW, Paffenbarger RS, Clark DG, Cooper KH, Gibbons LW. (1989). Physical fitness and all-cause mortality: a prospective study of healthy men and women. J Am Med Assoc 262: 2395-401.
6. Kodama S, Saito K, Tanaka S, Maki M, Yachi T, Asumi M, Sugawara A, Totsuka K, Shimano H, Ohashi Y, Yadama N, Sone H. (2009) Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events in healthy men and women: a meta-analysis. J Am Med Assoc 301(19): 2024-35
7. Støylen A, Conraads V, Halle M, Linke A, Presott E, Ellingsen Ø. (2012) Controlled study of myocardial recovery after interval training in heart failure: SMARTEX-HF—rationale and design. Eur J Prev Cardiol. Doi:10.1177/1741826711403252
8. Babraj JA, Vollaard NBJ, Keast C, Guppy FM, Cottrell G, Timmons JA (2009) Extremely short duration high intensity interval training substantially improves insulin action in young males. BMC Endocrine Disorders 9:3 doi: 10.1186/1472-6823-9-3
9. Musa DI, Adeniran SA, Dikko AU, Sayers SP (2009) The effect of a high-intensity interval training program on high-density lipoprotein cholesterol in young men. J Strength Cond Res 23(2): 587-592
10. Talanian JL, Holloway GP, Snook LA, Heigenhauser GJ, Bonen A, Spriet LL. (2010) Exercise training increases sarcolemmal and mitochondrial fatty acid transport proteins in human skeletal muscle. Am J Physiol Endocrinol Metab 299: E180-E188.
Blog moderated by Ann Gates, Founder of Exercise Works!
Guest blog by Richard J Godfrey PhD FACSM FBASES, Centre for Sports Medicine and Human Performance, School of Sport and Education, Brunel University, Middlesex, England.
Undertaking specific exercise training, as an athlete would do in preparation for an Olympic Games, is just as important for a hip replacement patient about to go through surgery or a cancer patient about to undergo chemo or radiotherapy. This activity is often referred to as ‘prehab’ and its aim is to improve the physical condition (fitness) of the patient prior to the upcoming ‘challenge’.
The benefits of being well-conditioned prior to major ‘systemic’ challenges extend widely and include: allowing the individual to cope better with the stress of the local tissue disruption and ‘systemic assault’ (e.g. the consequence of a major operation and use of GA; the use of radio- or chemo- therapy), faster recovery and a better response to rehabilitation, requiring fewer drugs, including pain killers and, through having greater sense of control, reduced anxiety and reduced psychological stress.
In designing appropriate exercise training for prehab there is no ‘one size fits all’ and indeed, the detail of the exercise programme should be customised to the individual. The most important planning considerations in this regard are current impediments to physical activity (PA), recent (last 3 months) PA history and what the event is that the individual is being ‘conditioned’ for.
Most patients are unlikely to be particularly fit (estimated from the fact that only 30% of the total population engage in even the minimum recommended amount of PA) and so any increase in daily physical activity, however modest should be adopted as improvements in fitness will result. The ideal scenario would be the patient who, as a bare minimum, already complies with the UK Department of Health PA guidelines, 2011 (‘Start Active, Stay Active’) and then undertakes a minimum of 12 weeks of more specific exercise training the purpose of which is to prepare the individual to better cope with the anticipated demands of the upcoming procedure. Whatever the individual’s starting point, for all patients the aim should be to improve aerobic power and muscle strength.
Aerobic power is generally often referred to as ‘VO2max’, the amount of oxygen that can be utilised during maximal exercise. As such it represents functional capacity and so, whether it is required for an extreme feat of human physical performance or for simply carrying out everyday tasks, having a ‘good’ VO2max is important. ‘Good’ of course is relative to the, soon to be imposed, demand. So, to run a 4-min mile requires a VO2max above 75 ml·kg-1·min-1 but simply to be functionally independent (an elderly individual living alone for example) requires a VO2max above 15-18 ml·kg-1·min-1 (Peterson et al, 2004). Immediately following coronary bypass, patients can be in the 10-15 ml·kg-1·min-1 range. The normal range for healthy, sedentary individuals is 35-40 ml·kg-1·min-1 for men and 30-35 ml·kg-1·min-1 for women. Although these last two ranges are the ‘norm’ they are not good ‘default settings’ for human beings and we should all be aiming to improve our fitness through being active throughout our entire lifespan and, on a weekly basis, exceed the Department of Health guidelines.
An inverse relationship has been demonstrated between VO2max and all-cause morbidity and mortality (Blair, 1989; Kodama, 2009), in other words the higher your VO2max the lower the risks of disease and death.
Improving fitness, as determined by increasing VO2max, is important as demonstrated by the 10% reduction in health risks with just a 1 ml·kg-1·min-1 increase in VO2max (Cavanagh, 2002, 2003). Hence, very small improvements in aerobic fitness can result in significant decreases in health risk. That is why, for all of us, simply doing a little more PA than we are currently accustomed to can make such a big difference. In addition, work with elite athletes has demonstrated that having a good VO2max also improves the individual’s ability to cope with a large training volume and to recover more quickly after training and competition. For patients, being able to recover faster makes good sense, whilst being able to handle a larger training volume will mean they will get fitter (exercise, like any drug, has a dose-response curve, but the difference with exercise is that, generally, the more training that is done the better the response). This all equals an easier and faster recovery with a better end point; better function, improved well-being and improved quality of life after the event.
Strength training is also important as it will contribute hugely to improved muscle function, the rate of recovery, the effectiveness of repair, better balance and posture control and the return to optimal function following treatment. It is important that strength training address the whole body not just the muscles which will be disrupted. This is because there will be a severe acute reduction in mobility and the impact of this can be lessened with strength training. For example, if the upper body is strong it will facilitate crutch use in the first month following the procedure (hip replacement for example). It will also allow earlier and more effective use of the affected body part.
The tenets of strength training have evolved little since Delorme and Watkins established the ‘3 sets of 10 repetition’ paradigm in the late 1940’s with soldiers, many of them amputees, returning from the Second World War. We now teach students that the most effective strength training programmes are governed by the mantra ‘high weight, low rep’. Hence, a very good programme involves determining, for a given muscle group or movement, the load which can be lifted 10 times before a rest is required. That set of 10 repetitions, with the identified load, is carried out three times with a number of muscle groups in each training session. Strength will of course improve and so the 10 rep max (10RM) should be reassessed every 3-4 weeks and training should continue with the new heavier load. In this way, two of the ‘Training principles’; overload (using a load greater than the individual is currently used to) and progression (regularly increasing the load to maintain the stimulus for continuing adaptation) can be applied.
When it comes to programming exercise training programmes, GP referral can be extremely useful and the fact that this is often funded for 12 weeks may be an excellent way to integrate prehab into everyday life prior to a medical procedure.
Blog moderated by Ann Gates, Founder of Exercise Works!