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European Heart Journal (1996) 17, 854-863 A comparison of the effects of strength and aerobic exercise training on exercise capacity and lipids after coronary artery bypass surgery D. Wosornu*, D. Bedfordf and D. Ballantynet * Department of Cardiology, Selly Oak Hospital, Birmingham B29 6JD, England; ^Department of Pathological Biochemistry, Royal Infirmary, Glasgow; \Department of Cardiology, Victoria Infirmary, Glasgow G42 9TY, Scotland Background Coronary artery surgery improves symptoms and prognosis in patients with angina. Aerobic exercise rehabilitation improves exercise capacity and prognosis in cardiac patients. Strength exercise training has not been extensively studied. Design We studied the effects of 6 months aerobic and strength exercise training after coronary artery surgery in 81 men, mean age 57 years. Results Treadmill time(s) increased by 130-3 (95% confidence interval 46-4 to 214-2) in the aerobic group; by 83-1 (0-9 to 165-3) in the strength group, and by 34-3 ( - 1 to 69-6) in the control group (P=004, control versus aerobic) after 3 months; and by 196-4 (112-2 to 280-7) in the aerobic group, by 122-7 (37-7 to 207-6) in the strength group and by 27 ( - 40-4 to 94-4) in the control group (P=0002, control Introduction Coronary artery surgery improves symptoms and quality of life in patients with angina. In certain subgroups the operation can also prolong life'1"31. Exercise is of value in primary 4 " 8 ', secondary'9""1 and tertiary1'21 prevention in cardiac disease. The effects of aerobic exercise training have been extensively studied in patients with coronary artery disease, including those who have undergone coronary artery surgery19""'13"161. It has been shown to improve prognosis'9"12'15'171 and to be of benefit in increasing functional capacity'13'15'17"2'1, reducing inducible ischaemia'221 and in the modification of risk factors'23"281. Strength or resistive exercise training has not been subject to such extensive evaluation. A few studies have been done in patients who have undergone versus aerobic, and P=003 control versus strength) after 6 months. The level of fitness improved more in the strengthtrained group, and there was a minor reduction in body weight and degree of fatness. There were no changes in lipoprotein levels. Aerobic exercise training causes early and sustained benefit in treadmill exercise capacity, while the effects of strength exercise training are later in onset. Exercise training alone did not influence lipid levels. Conclusion Cardiac rehabilitation programmes should be comprehensive, including advice on diet and other risk factor modifications in addition to exercise sessions involving aerobic and strength training elements. (Eur Heart J 1996; 17: 854-863) Key Words: Strength training, aerobic training, exercise capacity, lipids. prior aerobic exercise training, and it has been found to improve endurance and strength'29"321. We compared the effects of aerobic and strength exercise training after coronary artery surgery in previously untrained men. We assessed the effects on physique, exercise capacity, myocardial function and perfusion, heart rate and arrhythmias, lipoproteins and haemostatic factors. The results of our findings on haemostatic factors are the subject of a previous report'331. This is a report on the effects on physique, treadmill exercise performance and lipoprotein levels. Patients and methods The patients were 81 men referred from our hospital for coronary artery bypass surgery. They were randomized Revision submitted 4 September 1995, and accepted 23 October to three groups. Group 1 (n = 27) had no formal exercise 1995. training, and were the control group. They were not discouraged from pursuing their usual leisure activities, Correspondence Dzifa Wosornu. MD, Department of Cardiology, e.g. golf. Group 2 (n = 27) had 6 months of graduated Selly Oak Hospital, Birmingham B29 6JD, U.K. 0195-668X/96/060854 + 10 SI8.00/0 19% The European Society of Cardiology Effects of training after coronary bypass surgery 855 Table 1 Patients' characteristics at baseline Number Age: years (SD) Number of grafts IMA grafts (number of patients) Weeks post-surgery: median (range) Control Aerobic Strength 27 56-6 (70) 3-2 22 12 (6-28) 27 56-5 (8-9) 30 17 12 (6-48) 27 59-2 (6-4) 3-3 16 12 (6-44) Previous MI Diabetes Hypertension 11 1 1 17 1 4 15 1 1 Aspirin Dipyridamole Beta-blockers Diuretics ACE inhibitors 19 18 4 5 1 15 13 2 2 2 18 16 1 4 0 Current smokers Previous smokers Non-smokers Employed Off work Retired 4 14 8 8 7 11 3 15 9 6 6 12 1 17 6 6 6 12 52 (40-63) 50 (41-58) 59 (55-64) LVEF (%) mean (95% CI) ACE = angiotensin-converting enzyme; LVEF = left ventricular ejection fraction. supervised aerobic exercise training. Group 3 (n = 27) had 6 months of graduated supervised strength exercise training. Table 1 shows their details at baseline. Their mean age was 57-4 years (SD 7-6), 56% had previous infarcts, 60% were ex-smokers and 74% were not in full-time employment. Medications were constant throughout the study. There was no history of congestive heart failure. Left ventricular ejection fraction was measured by radionuclide angiography. The patients were assessed at baseline, at 3 months and at 6 months. One patient in group 1 was lost to follow-up after 8 weeks. There were no drop-outs in group 2. Two patients in group 3 dropped out after 2 weeks because of problems with their surgical scars; another moved away after 5 weeks. Exercise programme The programme was devised in conjunction with the Department of Physical Therapy to include movements involving all major muscle groups in exercises that are simple to perform. The patients attended the same location three times weekly for sessions of 12—40min. They were supervised by a physician, a cardiac rehabilitation nurse and a physiotherapist. The aerobic exercises were based on the Canadian Airforce XBX physical fitness programme. Exercises performed were arm circling, arm raising, step-ups, trunk rotation, star or stride jumps, crook-lying with trunk rotation and bridging, hip abduction side lying, standing trunk curls, trunk side flexion and running on the spot. Each patient started at the same level: with 3 to 10 repetitions of each exercise. The number of repetitions was increased over time to intensify gradually the work performed. Each patient had a chart of the exercises, and number of repetitions was marked on this. After 7 to 10 days at each level, the intensity was increased according to the patient's progress and performance, as assessed jointly by the physiotherapist, the physician and the patient. Strength exercises were based on a universal Multigym system, in which weights are connected by appropriately placed pulley systems designed to allow movement of the weights in specific directions. The exercises performed were bench press, military press, biceps curl, upright row, pull down, push down, pulley row, quadriceps curl, hamstrings curl and sit-ups. Each was started with the lightest weight of 2-5 kg, in three sets of 10 repetitions with periods of rest (45 s) between each element. The weight load was increased gradually, depending on the individual's progress and symptoms. A description of all the exercises is given in Appendix A. All the sessions ended with a cool-down period of 5 min riding on a stationary bicycle. By the end of the training period each patient should have been exercising at his perceived level of exertion. There was no heart rate or other cardiovascular monitoring. Perceived exertion is an acceptable surrogate for heart rate monitoring. It was hoped that, at the end of the programme, the patients would continue unsupervised exercise in the community. To decide on the level of that exercise, it was important for them to learn to rely on their symptoms, rather than their heart rate. The intensity of exercise training was in keeping with recommendations of the American Society of Sports Medicine1341, and the American Heart Association1'31. Eur Heart J, Vol. 17, June 1996 856 D. Wosornu et al. Exercise tests The exercise tests were done using a Marquette Case II computerized treadmill system. Full 12-lead electrocardiographs, with automatic ST segment analysis are printed every 3 min. The ST segments are measured 60 ms from the J-point, and values exceeding 01 mV are considered positive for ischaemia. Heart rate, exercise time, maximum ST segment depression, estimated workload in metabolic equivalents, percentage of target heart rate reached are also recorded. A modified Balke protocol was used (Appendix B). This protocol was chosen because it was used in the pre-surgery evaluations and most of the patients were already familiar with it. In addition, there is a gradual increase in work-load with each stage, making it a physiologically sound means of testing exercise capacity. All tests were carried out in the morning after an overnight fast. The necessary blood samples for lipoproteins and haemostatic factors were taken prior to the exercise test. Each patient had four exercise tests during the programme for the purposes of exercise test data: two at baseline (average taken as baseline performance) and one each at 3 and at 6 months. Blood pressure was measured manually at rest and 2 min into each stage. The tests were symptomlimited, unless significant hypotension (a fall in systolic blood pressure greater than 10 mmHg from the previous reading), or ventricular tachycardia occurred. The following were recorded: resting heart rate, resting systolic blood pressure, submaximal heart rate, submaximal rate-pressure product, maximum rate-pressure product, maximum heart rate, maximum treadmill time, maximum workload, maximum ST segment depression, percentage of target heart rate achieved, and heart rate at 5 min into recovery (FHR). Target heart fate is 220 minus age of patient. A recovery rate=(maximum heart rate — FHR/5) and recovery rate ratio=maximum heart rate - FHR/FHR were derived as further measures of fitness. Clinical examination Patients had body weight, body mass index and skin fold thickness measured. Body mass index is weight/height2. Skin fold thickness was measured with Harpenden calipers at four sites — biceps, triceps, scapula and abdomen. The biceps and triceps measurements were taken midway down the muscles, scapula measurement was taken halfway down its medial aspect, and the abdominal measurement was taken at the anterior superior iliac spine. The sum of the four readings was used as a measure of body fat, a well recognised means of assessing body fat in nutritional and exercise training studies1355. Lipoprotein analysis The assays were performed by technicians who were not aware of the patients' groups. Total cholesterol and Bat Heart J, Vol. 17, June 1996 triglyceride were assayed by enzymatic colorimetric tests (Boehringer Mannheim). Lipoproteins were assayed by beta-quantification. HDL subfraction 2 and 3 masses were estimated by rate zonal ultracentrifugation with ultraviolet scanning (Beckman Instruments). Apolipoprotein Al and B were measured by immunochemical assay (Orion Diagnostica). Statistical analysis Results were analysed on an intention-to-treat basis, using SPSS/PC + version 4 0 statistical data analysis program. Descriptive statistics were done, followed by tests of normality. Within- and between-group differences were assessed by analysis of variance (ANOVA) with application of Scheffe test for normal data, and Kruskal-Wallis test for non-normal data. When this was significant (/><005), the analysis was taken further. Paired 't'-test or Wilcoxon test was done for within-group data, and unpaired 't'-test or MannWhitney U test was done for between-group data. Results are expressed as the mean with 95% confidence interval. Results Records of the attendance and exercise work-out were kept for each patient. Group 2 attended 64% and group 3 attended 63% of their training sessions. There were no deaths or cardiac arrests during the exercise sessions. Clinical examination The results of weight, body mass index and skin fold thickness are shown in Table 2. Group 1 was heavier than the other two groups (P=0-07 at baseline). Weight in groups 1 and 2 increased slightly over time, while that in group 3 was relatively stable. At 3 months, group 1 gained 1 -3 kg, group 2 gained 0-9 kg, and group 3 lost 0-3 kg. The patients were overweight since their body mass index exceeded 25. The pattern for body mass index was similar to that of body weight. At 3 months, group 1 increased body mass index by 0-4, group 2 increased by 0-3 and group 3 decreased by 0 1 . Skin fold thickness was similar in all groups at baseline, and fell with training in group 3 alone. Exercise performance Common symptoms limiting the exercise tests were dyspnoea, fatigue, leg ache and chest pain. As would be expected, 94% were cured of chest pain by coronary artery surgery, with only five patients stopping the test because of this symptom. This pattern did not change during the training period. Exercise performance (Table Effects of training after coronary bypass surgery Table 2 Weight (kg), body mass index (kg. m (mm) — mean (95% CI) 857 2 ), skin fold thickness Control Aerobic Strength Weight Baseline 3 months 6 months 80-5 (76-1 to 84-8) 81 8 (77-4 to 861) 81 6 (77-6 to 85-6) 76-3 (70-7 to 8 1 9 ) 77-2 (71-6 to 82-8) 77-1 (71-4 to 82-8) 72-6 (68-5 to 76-6) 72-3 (68-2 to 76-4)* 72-7 (68-6 to 76-7)f Body mass index Baseline 3 months 6 months 27-5 (26-2 to 28-9) 27-9 (26-6 to 29-3) 27-9 (26-6 to 29-2) 26-9 (25-6 to 28-3) 27-2 (25-9 to 28-6) 27-2 (25 8 to 28-6) 25-8 (24-4- to 27 1) 25-7 (24-3 to 27)* 25-8 (24-5 to 27) Skin fold thickness Baseline 3 months 6 months 47-5 (41-5 to 53-4) 48-9 (43 to 54-8) 47-4 (42-3 to 52-5) 46-6 (40-6 to 52-6) 46-4 (40-5 to 52-2) 451 (393 to 50-9) 40-4 (36-8 to 44) 39-7 (36-8 to 42-6)J 38 (35 to 41)f •ANOVA />=0-02; t/ J =003; J/>=0-04. Table 3 Treadmill exercise performance and interval changes (s) — mean (95% CI) Absolute values Baseline 3 months 6 months Interval changes 0-3 months 0-6 months 3-6 months Control Aerobic Strength P value 683-8 (558-6 to 809-1) 718-2 (585-3 to 851) 710-8 (575-6 to 846) 650-5 (549-7 to 751-3) 780-8 (673-2 to 888-4) 846-9 (746-5 to 947-3) 784-2 (657-8 to 910-5) 867-3 (743-6 to 991) 906-8 (785-3 to 1028-3) ns ns 0-03* 130-3 (46-4 to 214-2) 196-4 (112-2 to 280-7) 66-2 (13 to 119-3) 831 (0-9 to 165-3) 122-7 (37-7 to 207-6) 39-5 (5-6 to 73-5) 004f 0-002f 0-05t 34-3 ( - 1 to 69-6) 27 ( - 40-4 to 94-4) - 7-3 ( - 60-6 to 45-9) 'Control versus strength; fcontrol versus aerobic. 3) improved in group 2 after 3 months, and was maintained at 6 months, in comparison with group 1. In group 3, improvement in exercise performance did not reach statistical significance until 6 months. The results for estimated maximum workload (Table 4) in metabolic equivalents (1 met = 3-5ml 0 2 m i n ~ ' ) follow a similar pattern, but with more striking statistical differences. There were no significant differences in resting heart rate and systolic blood pressure, submaximum and maximum heart rates, maximum ST segment depression, submaximum rate-pressure product, 5-min heart rate, or percentage target heart rate between the groups. Within group 3, resting heart rate fell by 3 beats. min~', submaximum heart rate by 8 beats . min~', and submaximum rate-pressure product by 3946 beats . m i n ~ ' . mmHg~'. They also achieved higher maximum rate-pressure product, recovery rate and recovery rate ratio compared to group 1 (Table 5). Group 3 may therefore have become fitter than they had been prior to training. Lipids and lipoprotein levels Tables 6-8 show the results of the lipid and lipoprotein analysis. The levels of total cholesterol, triglycerides and their subfractions did not alter with either mode of exercise training. There were no statistically significant differences in any of the levels at any time. Discussion This study was carried out to compare the effects of aerobic and strength exercise training in a group comprising only post-bypass patients. The results on exercise capacity and safety should help to dispel the fears surrounding strength training in cardiac patients. The weight gain in the control group was not accompanied by an increase in skin fold thickness, while that in the aerobic group was associated with a small drop in skin fold thickness. This is usually explained in terms of a gain in muscle mass as a result of exercise training and is supported by the pattern of lower skin fold thickness in the strength group without much change in body weight. A 10 mm increase in the sum of four skin folds corresponds to a 5% increase in fatness1351. The changes in the strength group therefore represent, at most, a 1% reduction in fatness. Physical fitness and residual ischaemia were estimated by the parameters that were recorded. A resting bradycardia and rapid recovery of heart rate after Eur Heart J, Vol 17, June 1996 858 D. Wosornu et al. Table 4 Estimated work-load and interval changes (mets) — mean (95% CI) Control Aerobic Strength P value Absolute values Baseline 3 months 6 months 7-5 (61 to 9) 7 8 (6-3 to 9 2) 7-8 (7-3 to 9 3) 7 (6-2 to 7-9) 8-4 (7-3 to 9-5) 9 (7-9 to 10-2) 8-6 (7-3 to 10) 9-3 (8 to 10-5) 10 (8-6 to 11-3) ns ns 003* Interval changes 0-3 months 0-6 months 3-6 months 0-2 ( - 0-2 to 0-7) 0-2 ( - 0 - 5 to 1) 0 ( - 0-6 to 0 6) 1-4 (0-7 to 21) 2 (1-2 to 2-8) 0 6 (01 to 1-2) 0-6 ( - 0 - 2 to 1 5) 1-3 (0-4 to 2-3) 0-7 (0-3 to 1-2) 0009f 0-002| 0-05* 'Control versus strength; fcontrol versus aerobic. Table 5 Maximum rate-pressure product (beats . min ' . mmHg ' ery rate (beats . min ~ '); recovery rate ratio — mean (95% CI) Control Aerobic 102); recov- Strength P value Maximum rate-pressure product Baseline 250-8 (227-3 to 274 3) 232 8 (211- 6 to 254 1) 256-5 (235-7 to 277-2) 3 months 252-1 (224-5 to 279-8) 234-3 (208- 2 to 260-3) 260-0 (238-2 to 281-9) 6 months 231-8 (209-4 to 254-2) 235 3 (210- 3 to 260-3) 265-7 (246-2 to 285-2) ns ns 002* Recovery rate Baseline 3 months 6 months 10 (8-9 to 11-3) 10 2 (8-9 to 116) 9 (7-3 to 10-7) Recovery rate ratio Baseline 3-3 (3 to 3-6) 3 months 3-4 (31 to 3-7) 6 months 3-2 (2-7 to 3-6) 10-5 (9-6 6o 11-4) 10-7 (9-5 to 11-9) 10-3 (8-6 to 12) 10-6 (9-6 to 11-6) 11 (9-9 to 12-2) 11-8 (10-6 to 13) ns ns 001* 3-6 (3-4 to 3-8) 3-6 (3-3 to 3-8) 3-4 (31 to 3-8) 3-4 (3-2 to 3-7) 3-4 (3 to 3-8) 3-7 (3-4 to 4) ns ns 0-03* 'Control versus strength. Table 6 Total cholesterol and triglyceride levels (mmol. I ') — mean (95% CI) Control Aerobic Strength P value Cholesterol Baseline 3 months 6 months 6-5 (61 to 6-9) 6-4 (5-9 to 5-9) 6-2 (5-7 to 6-7) 6-2 (5-7 to 6-7) 61 (5 7 to 6-5) 6-2 (5-8 to 6-8) 6-6 (6-2 to 6-9) 6-3 (5-9 to 6-6) 6-4 (6-0 to 6-8) ns ns ns Triglycerides Baseline 3 months 6 months 2-1 (1-7 to 2-5) 2-3 (1-8 to 2-9) 2-2 (1-7 to 2-7) 2-0 (1-6 to 2-4) 2-2 (1-8 to 2-6) 21 (1-7 to 2-5) 1-9 (1-6 to 2-4) 1-9 (1-6 to 2-2) 1-9 (1-6 to 2-3) ns ns ns exercise, low submaximal heart rate and rate-pressure product indicate physical fitness. The maximum ratepressure product is an indicator of myocardial oxygen demand at peak exercise, while maximum treadmill time and work-load are indicators of fitness and disease severity11819-361. ST segment depression is a measure of ischaemia. In general, its absence in exercise testing is said to imply a good prognosis. There are, however, some doubts about the prognostic significance of ST Eur Heart J, Vol. 17, June 1996 segment changes during exercise tests after coronary artery surgery1 7]. In this study, there were no changes in ST segment responses after exercise training. Exercise training induces a training response comprising a resting bradycardia, reduced heart rate and rate-pressure product at submaximal exercise, increased exercise duration, increased maximum oxygen consumption and cardiac output and a shorter recovery time11719'2'1. There may also be an increase in the Effects of training after coronary bypass surgery 859 Table 7 Low-, high- and very-low-density lipoprotein levels (mmol. I ') —mean (95% CI) Contro Aerobic Strength P value LDL Baseline 3 months 6 months 4-4 (40 to 4-7) 4-3 (3-9 to 4-6) 4-0 (3-7 to 4-4) 4-1 (3-7 to 4-5) 4-0 (3-6 to 4-3) 4 0 (3-6 to 4-3) 4-4 (4-2 to 4-7) 4 3 (4-0 to 4-6) 4-3 (4-0 to 4-7) ns ns ns HDL Baseline 3 months 6 months 1-2 (11 to 1-3) 11 (10 to 1-2) 1-1 (10 to 1-3) •2 (1 1 to 1-3) •2 (1 1 to 1-3) •2 (11 to 1-3) 1 2 (11 to 1-3) 1-2 (10 to 1-3) 1-2 (11 to 1-4) ns ns ns VLDL Baseline 3 months 6 months 1-0 (0-8 to 1-2) 11 (0-8 to 1-4) 10 (0-8 to 1-3) •0 (0-7 to 1-4) 0 (0-8 to 1-3) •0 (0-8 to 1-3) 0-9 (0-7 to 11) 0-9 (0-7 to 1-0) 0-9 (0-7 to 10) ns ns ns LDL = low-density lipoprotein. HDL = high-density lipoprotein. VLDL = very-low-density lipoprotein. Table 8 HDL subfraction 2, HDL subfraction 3 ( m g % ) , apolipoprotein Al and B (g.l ') — mean (95% CI) Control Aerobic Strength P value HDL subfraction 2 Baseline 3 months 6 months 58-4 (46-9 to 69-9) 58-5 (47 1 to 69-9) 62-7 (49-2 to 76-1) 680 (52-4 to 83-4) 64 1 (51 9 to 76 4) 630 (49-7 to 76-2) 61-9 (48-7 to 75-1) 62-1 (47-8 to 76-4) 65-5 (50-8 to 80-2) ns ns ns HDL subfraction 3 Baseline 3 months 6 months 224-5 (203-3 to 245-6) 221-8 (202-8 to 240-8) 219-7 (202-0 to 237-4) 225-9 (200-5 to 251-3) 222-9 (207-7 to 238-2) 227-9 (207-9 to 247-9) 240-4 (222-3 to 258 4) 225-2 (200-2 to 250-2) 235-9 (212-8 to 259-0) ns ns II (1-1 to 1-2) ns Apolipoprotein Al Baseline 3 months 6 months 1-2 (1 1 to •2) 11 (1-1 to •2) 11 (1-0 to •2) 1-3 (1-1 to 1-4) 1-2 (1-0 to 1-4) 1-2 (11 to 1-3) ns 11 (10 to 1-2) 11 (11 to 1-2) Apolipoprotein B Baseline 3 months 6 months 1-2 (11 to 1-4) 1-2 (11 to 1-3) 11 (1-0 to 1-3) 11 (10 to •3) 11 (10 to •2) 11 (10 to •3) 1-2 (1-1 to 1-3) 11 (1-0 to 1-2) 1-2 (11 to 1-3) ns ns ns exercise test work-load at which ischaemia occurs[22>381. The exercise-trained groups in this study achieved these to a varying extent. The results support the view that exercise training improves exercise performance. Aerobic exercise training in these patients caused early and sustained improvement in treadmill performance, while the benefits of strength exercise training were of later onset. However, there were no major differences in treadmill performance between the two types of exercise training at the end of the 6 months' training period. The improvements in exercise performance in the strength group were associated with an increased level of fitness. After 6 months, there was a 30% increase in treadmill ns ns time in the aerobic group and a 16% increase in the strength group, compared with an overall increase of only 5% in the control group. The use of the treadmill to assess those undergoing strength training may have underestimated their achievements, as the effect of training tends to be very specific1391. The strength-trained group did show significant improvements in exercise capacity on the treadmill. This may partly be because their programme included leg-strengthening exercises, the repetitive nature of which could have improved their endurance. Specific tests of strength, such as the one-repetition maximum, may have shown up even greater benefits. One can expect that these improvements in exercise capacity will Eur Heart J, Vol. 17, June 1996 860 D. Wosornu et al. be translated into major gains in the performance of everyday activities, including those that involve lifting and carrying. Studies on exercise training after coronary artery surgery Previous studies have not addressed the effects of strength training after coronary artery surgery. The main results of this study are in keeping with studies on aerobic training in which post-bypass patients have been included. These patients are usually part of a group with coronary artery disease. Their training has ranged from 3 times a week to daily sessions of 16-60 min, and from 6 weeks to 32 months. Cardiopulmonary exercise testing was used in some studies. Post-bypass patients achieved as much as post-infarction or angina patients'l6-4°l. Maximum oxygen uptake increased, with no change in resting heart rate or blood pressure, after 32 months of daily aerobic exercise after coronary artery surgery14'1 Ninety per cent of the total improvement in functional capacity had occurred by 4 months. In our exercisetrained groups, 67-69% of the total improvement had occurred by 3 months. Other studies of aerobic exercise training have also shown increases in maximum oxygen uptake143'44'. In the PERFEXT study, post-bypass patients formed a third of the group and they showed the haemodynamic benefit (such as higher maximum oxygen uptake) demonstrated in the other patients'161. All the studies therefore show that aerobic exercise training does improve exercise capacity after coronary artery surgery, and support the results of the present study. Studies involving strength training in cardiac patients Strength training and resistance exercises are usually recommended in cardiac patients only after a period of aerobic training has been completed145""*71. There are a few reports on its effects in normal subjects and cardiac patients, and most would recommend circuit weight training as was used in this study130"3247'481. After 6 months of supplementary circuit training in 16 men in cardiac rehabilitation, a significant improvement in strength was observed, but there were no changes in body weight or percentage fat[311. In our study, only the strength-trained group showed a reduction in skin fold thickness; their weight and body mass index remained relatively stable. The aerobic-trained group gained weight, as did the control group. Where direct comparisons have been made between aerobic and strength training, the physiological responses to the latter have been less alarming than anticipated'491. During circuit weight training, percentage VO2 max was consistently lower than that predicted for dynamic exercise, such as running or cycling, for a given percentage of maximum heart rate. Therefore, using heart rate to prescribe the Eur Heart J, Vol. 17, June 1996 intensity of weight training exercise resulted in a lower level of aerobic metabolism than during dynamic exercise150'. When circuit training was compared with treadmill exercise, there was less ischaemia, lower peak heart rate and rate-pressure product, similar peak systolic pressure, but higher diastolic pressure15'1. In that study, as in ours, reliance was placed on symptomatic status to judge the intensity of effort in the training sessions. In another study, peak heart rate and rate-pressure product were similar, but peak systolic blood pressure was higher during aerobic exercise than during circuit training. Treadmill time increased in both groups (as in this study), but upper body strength increased only in the circuit weight training group1521. Combined weight lifting and aerobic exercise training resulted in greater improvements in both cycle ergometer performance and one-repetition maximum than did aerobic training alone153'. In our patients, the 5-min ride on a bicycle was performed as a cool-down exercise by all the exercisetrained patients, and was a constant feature. The different interventions were those of strength-training using universal Multigym equipment, and aerobic-training based on the Canadian Airforce XBX physical fitness programme. Exercise training and lipid levels The total cholesterol and low-density lipoprotein levels were higher than is ideal for post-bypass patients, but is in keeping with previous studies from Scotland'541. The lack of effect of the exercise programmes may be linked to their failure to cause a full training effect. Exercise training has been found to have a variable and, at times, transient effects of lipids. In a meta-analysis of 95 trials, it was found that changes in body weight are relevant to lipoprotein levels, with subjects who lose weight showing more significant improvements in lipid levels'271. In postbypass patients, there were no changes in body weight, cholesterol, low-density lipoprotein or apolipoprotein B levels, triglycerides decreased and high-density lipoprotein increased after 2 months' aerobic training, but by 1 year results were no different from the control group'281. In some reports, improvements in lipid levels have been found to correlate best with changes in VO2 max'55'561, while others have shown increases in highdensity lipoprotein with exercise training without changes in diet, smoking or the achievement of a training effect'571. In a previous study from this institution, aerobic exercise training for 6 months in 19 men postmyocardial infarction caused favourable changes in lipoprotein levels, but there was no change in total cholesterol levels and no relationship was found between treadmill performance and lipid levels'241. Full cardiac rehabilitation consisting of physical fitness, psychosocial well-being and risk factor modification for 3 months resulted in a fall in total cholesterol by 0-3 mmol. 1~', but it remained high in those with initial values above 6-5 mmol. 1~ '; high and low-density lipoprotein did not change1231. The level of total cholesterol in our patients Effects of training after coronary bypass surgery was about 6-5 mmol. 1 ', and was not altered by exercise training. The effects of strength training on lipids have been assessed in dyslipidaemic patients, athletes, and a few patients with coronary artery disease. Results are varied. Some show no changes in lipid levels'58', but there are some reports of beneficial effects of strength training on lipid levels'59'601. Limitations and strengths of the study We were unable to perform cardiopulmonary exercise testing. This would have improved the objectivity of the assessment of exercise performance. It would have helped to determine whether the significant improvements in treadmill time were secondary to increases in leg strength or improved cardiovascular responses. It is difficult to be certain of the extent to which motivation is a factor in exercise performance without measuring oxygen consumption and anaerobic threshold. Each patient served as his own control. Assuming that the patients' characters did not change during the study, the 'motivation factor' remained constant. We did not collect data on individual variation in progress with the exercise programme. Haemodynamic and cardiac monitoring were not done during training. Some may consider this to be an important omission, but no adverse events were recorded during training. It was not possible to determine accurately the intensity of exercise training without measures of haemodynamic responses. Assessments of upper or lower limb strength, e.g. using one repetition maximum, were not included in the protocol when the study was devised. We were therefore unable to determine whether any of the groups had increases in muscle strength after training. The groups comprised only post-bypass patients, randomized to different interventions, and there was a control group. Although no formal dietary or risk factor modification was done, such advice was available to all patients and would have been the same. The sessions and studies were supervised by the same personnel throughout the programme. Conclusions Aerobic and strength exercise training result in significant improvements in treadmill exercise performance after coronary artery surgery. Exercise training alone did not cause clinically significant changes in lipoprotein levels, body weight or percentage body fat. Cardiac rehabilitation programmes should probably include advice in dietary and risk factor modifications, and psychosocial support in addition to aerobic and strength exercise training. We thank Miss Rita Smith and her staff for help with the exercise tests, Miss Elizabeth Lightbody for help with the exercise sessions and physiotherapy, and the technicians who processed the samples for lipoprotein analysis. 861 References [1] Alderman EL, Bourassa MG, Cohen LS el al. 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The rate-pressure product as an index of myocardial 1134-9. oxygen consumption during exercise in patients with angina [59] Hurley BF. Effects of resistive exercise training on lipoprotein pectoris. Circulation 1978; 57: 549-56 lipid profiles: a comparison to aerobic training. Med Sci [37] Yli-Mayry S, Huikun HV, Airaksinen J, Linnaluoto MK, Sports Exer 1989; 21: 689-93. Takkunen JT. Usefulness of a postoperative exercise test [60] Hurley BF, Hagberg JM, Goldberg AP et al. Resistance for predicting cardiac events after coronary artery bypass training can reduce risk factors without altering VO2 max or grafting. Am J Cardiol 1992; 70: 56-9. percent body fat. Med Sci Sports Exer 1988; 20: 150-4. [38] Todd IC, Bradnam MS, Cooke MBD, Ballantyne D. The effects of daily high intensity exercise on myocardial perfusion in angina pectoris. Am J Cardiol 1991; 68: 1593-9. Appendix A [39] Jones DA. Strength of skeletal muscle and the effects of training. Br Med Bull 1992; 48: 592-604. Aerobic exercise programme [40] Adams WC, McHenry MM, Bemauer EM. Long term physiologic adaptations to exercise with special reference to performance and cardiorespiratory function in health and Arm circling. Stand with your feet slight apart. Abduct disease. Am J Cardiol 1974; 33: 765-75. arms and rotate at shoulders, forwards and backwards, [41] Oldridge NB, Nagle FJ, Balke R, Corliss RJ, Kahn DR. starting with five in each direction. Aortocoronary bypass surgery: effects of surgery and 32 months of physical conditioning on treadmill performance. Step-ups. Step up and down the 20 cm step at moderate Arch Phys Med Rehabil 1978; 59: 268-75 pace, starting with 10 repetitions. [42] Horgan JH, Teo KK, Murren KM, O'Riordan JM, Gallagher T. The response to exercise training and vocational counsel- Trunk rotation. Stand with your feet slightly apart, ling in post myocardial infarction and coronary artery bypass hands on hips. Rotate trunk to left and right, starting surgery patients. Ir Med J 1980; 73. 463-9. with five to each side. Eur Heart J, Vol. 17, June 1996 Effects of training after coronary bypass surgery Crook lying trunk rotation. Lie on your back, arms at side, knees flexed. Rotate hips from side to side, starting with five to each side. Star Jumps. Stand with your feet together. Jump up while abducting arms and legs fully, then return to starting position. Start with three. Side lying hip abduction. Lie on your right side, with right arm stretched above head, left arm supporting upper body at chest level, right knee flexed. Abduct left leg fully, and return to starting position. Repeat on left side, abducting right leg. Start with five on each side. Standing trunk curls. Stand with your feet together, arms at side. Bend knees with arms stretched forwards, and lower your body towards the mat. Return to starting position. Start with three. Crook lying bridging. Lie on your back with knees flexed. Raise hips while keeping feet and shoulders on the mat, and return to starting position. Start with five. Arm raising. Stand with your feet together, arms at sides. Raise arms forward above head and return to starting position. Start with five. Trunk side flexion. Stand with your feet slightly apart. Flex trunk to right, sliding the right hand down the right leg, and repeat on the left side. Start with three on each side. Running on the spot. Raise your feet at least 10-20 cm off mat while running on the spot for 1 min initially. by pulling the bar up, until arms are fully flexed, and return to start. Upright row. Stand facing equipment. With your arms extended, palms down, pull the bar up towards your chin, and move elbows outwards at the same time to raise the weights. Return to starting position. Pull down. Sit on stool with equipment behind body. Raise weights by pulling bar down towards shoulders, and return to starting position. Push down. Stand facing equipment. Bend your arms with palms down and raise weights by pushing bar downwards until arms are fully extended. Return to starting position. Pulley row. Sit on mat, legs fully stretched facing equipment. Reach for the bar and raise weights by pulling the bar towards your body, and return to starting position. Quadriceps curl. Sit on the edge of the bench. Hold cushioned bar with flexed ankles and raise weights by extending the knees. Return to starting position. Hamstrings curl. Lie prone on the bench, with cushioned bar resting on back of ankles. Raise weights by flexing knees. Return to starting position. Sit ups. Lie supine on the mat, with legs stretched. Grip fixed cushioned bar with ankles. Raise upper body, try to touch your knees with your forehead and return to starting position. Start with three repetitions. Appendix B: exercise test protocol Strength exercise programme Bench press. Lie on your back on the bench, feet on the floor, equipment behind head. Raise weights by pulling bar towards your head, and return to starting position. Military press. Kneel facing equipment. Raise weights by pushing the bar from chest level to above your head, fully extending your arms, and return to starting position. Biceps curl. Stand facing equipment. Bend your forearms, palms up, elbows tucked into sides. Raise weights 863 Stage 1 2 3 4 5 6 7 Speed (k.p.h.) Gradient (min) 3 •6 9 12 15 18 21 3-2 4-8 4-8 4-8 4-8 4-8 7-2 0 4 8 12 16 20 20 Time Mets 3 5 7 8 10 12 15 Eur Heart J, Vol. 17, June 19%