Up to 25% of patients with chronic heart failure (CHF) have type 2 diabetes mellitus (2DM) [
The hypothesis was that training in warm water would be safe and result in improvement in physical performance, muscle function, and metabolic control in patients with CHF and 2DM.
Therefore the aim of this study was to investigate the effect of aquatic exercise in patients with CHF and 2DM.
Twenty patients (four women) with stable CHF and 2DM in NYHA class II or III, ejection fraction (EF) <50%, age above 55 years were included. Heart failure medication had to be stable for the previous three months. Exclusion criteria were peripheral artery disease, chronic pulmonary disease, status after stroke, or other disabling diseases that might interfere with the exercise protocol. The process of patient recruitment is described in Figure
Demographic data of patients with chronic heart failure and type 2 diabetes mellitus.
Variables | Training | Control | |
---|---|---|---|
Age (years) | ns | ||
Sex (F/M) | ns | ||
Weight (kg) | ns | ||
Height (cm) | ns | ||
Duration of CHF (years) | ns | ||
Duration of 2DM (years) | ns | ||
LVEF (%) | ns | ||
Etiology of CHF (IHD/DCM/HT) | ns | ||
NYHA class (II/III) | ns | ||
Chronic atrial fibrillation ( | 5 | 3 | ns |
Beta blockers ( | 9 | 8 | ns |
ACE-inhibitors ( | 8 | 9 | ns |
Diuretics ( | 9 | 9 | ns |
Digitalis ( | 2 | 5 | ns |
Insulin ( | 5 | 3 | ns |
Anti diabetics ( | 5 | 8 | ns |
Acetyl-salicylic acid ( | 5 | 8 | ns |
Warfarin ( | 5 | 3 | ns |
F/M: female and male, LVEF: left ventricular ejection fraction, NYHA: New York Heart Association classification, IHD: ischemic heart disease, DCM: dilated cardiomyopathy, HT: hypertension, ACE: angiotensin converting enzyme,
The inclusion process of patients.
All patients performed the below given tests within 10 days before the randomisation and then during the last 10 days of the study period. Patients started on the first day with venous blood samples followed by an acquaintance test on the ergospirometer. Thereafter, questionnaires were filled out and the six-minute walk test performed. Finally patients performed on day 4–6 the maximal test on the ergospirometer and on day 8–10 the muscle tests.
Work rate and peak oxygen uptake (
A standardised six-minute walking test was used to assess exercise capacity related to activities of daily living. The patients were asked to walk as far as possible during six minutes on a premarked 30-meter walkway [
For measurement of isometric and isotonic strength and isotonic endurance the Biodex III (Biodex medical systems, New York, USA) was used. The test was preceded by a 5-minute warmup on a test bicycle. The subjects sat with a hip angle of 90°, and the right leg was attached to the lever arm of the dynamometer. Isometric knee extension strength was measured at a 60° knee angle. Isokinetic concentric strength was measured at 60°/s and at 180°/s for knee extensors. Isokinetic endurance was evaluated as the reduction of torque (in percent) between the first and the last three extensions in a series of 50 maximal contractions with an angle of 180°/s. Handgrip strength, the maximum grip force, and the mean value of the 10-second sustained grip was assessed by Grippit (AB Detector, Göteborg, Sweden). Clinical endurance tests, that is, unilateral isotonic heel-lift, bilateral isometric shoulder abduction and unilateral isotonic shoulder flexion were also measured. The test procedures have been described previously [
Health-related quality of life was measured using the Medical Outcome Short Form—36 (SF-36) [
Venous blood samples for assessing plasma glucose, HbA1c, serum insulin, serum C-peptide, and serum lipids were taken before and after the intervention period after an overnight fast and analysed according to the European Accreditation system [
The training programme comprised 45-minute sessions in a heated pool (33°-34°C), three times a week over an eight-week period. The patients trained as a group following a low-to-moderate exercise level, that is, 40 to 75% of maximal heart rate reserve (HRR). The basis posture was standing with water just below neck level. The programme focused on peripheral muscle training but central circulatory exercises were also included as earlier described [
The SPSS 12.0 for Windows (Chicago, IL, USA) was used to analyse the data.
Ratio and interval data are given as mean (±1 SD or 95% CI) and ordinal data as median and range. Wilcoxon-matched pairs signed rank sum test was used for comparisons of paired observations within each study group. The Mann Whitney
Aquatic exercise was well tolerated by the patients and no adverse events occurred during the aquatic exercise. Two patients in the training group were withdrawn, due to a peripheral ulcer caused by new shoes, increased symptoms of CHF, respectively. One patient in the control group was withdrawn, due to family problems. The average adherence (total number of attended sessions) was 92%. HRR during training ranged between 40% and 60% during peripheral muscle training exercises and between 55% and 75% during the aerobic exercises. In the training group two patients needed to reduce their insulin and one to take away the oral antidiabetics due to hypoglycaemia.
Physical performance was significantly improved in the training group compared with the control group, regarding work rate,
Muscle function before and after aquatic exercise in patients with chronic heart failure and type 2 diabetes mellitus.
Knee extension in Biodex III. Isokinetic | Before ( | After ( | |||
---|---|---|---|---|---|
Peak torque (60°s Nm) right leg | T | 122 ± 41 | 127 ± 34 | ns | ns |
C | 102 ± 30 | 98 ± 32 | ns | ||
Peak torque (180°s Nm) right leg | T | 88 ± 28 | 119 ± 54 | 0.02 | <0.001 |
C | 66 ± 22 | 64 ± 24 | ns | ||
Endurance decline in %, left leg | T | 46 ± 17 | 44 ± 13 | ns | ns |
C | 51 ± 14 | 52 ± 16 | ns | ||
Isometric | |||||
Peak torque | T | 136 ± 41 | 136 ± 40 | ns | ns |
60° (N) right leg | C | 109 ± 37 | 101 ± 32 | ns | |
Hand strength | |||||
Peak force (N) | T | 342 ± 121 | 385 ± 106 | ns | ns |
Right hand | C | 248 ± 82 | 221 ± 62 | 0.04 | |
Peak force 10 s (N) | T | 289 ± 108 | 323 ± 89 | ns | ns |
Right hand | C | 207 ± 77 | 187 ± 62 | ns | |
Clinical endurance tests | |||||
Heel lift (n.o) | T | 14 ± 7 | 18 ± 6 | 0.01 | 0.01 |
C | 14 ± 4 | 14 ± 5 | ns | ||
Shoulder flexion (n.o) | T | 26 ± 11* | 36 ± 12 | 0.02 | 0.03 |
C | 17 ± 8 | 17 ± 28 | ns | ||
Shoulder abduction (s) | T | 75 ± 25 | 89 ± 27 | 0.01 | <0.001 |
C | 64 ± 26 | 56 ± 22 | 0.03 |
T: Training group, C: control group, ns: not significant, n.o.: number of, *:
Work rate (a), peak oxygen uptake
Hba1c decreased during aquatic exercise, but there was no significant improvement in fasting plasma glucose, insulin, c-peptide, or blood lipids after eight weeks of training (Table
Metabolic function before and after aquatic exercise in patients with chronic heart failure and type 2 diabetes mellitus.
Variables | Before ( | After | |||
---|---|---|---|---|---|
Hba1c (%) | T | 0.01 | ns | ||
C | ns | ||||
P-Fasting glucos (mmol/L) | T | ns | ns | ||
C | ns | ||||
S-Insulin (mU/L) | T | ns | ns | ||
C | ns | ||||
S-C-peptide (nmol/L) | T | ns | ns | ||
C | ns | ||||
S-Triglycerides (mmol/L) | T | ns | ns | ||
C | ns | ||||
S-Cholesterol (mmol/L) | T | ns | ns | ||
C | ns |
P: plasma, S: serum, T: Training group, C: control group.
Compared to a Swedish reference population [
No significant changes in disease specific quality of life and grade of anxiety and depression occurred after eight weeks of aquatic exercise.
LHFQ | Before ( | After ( | HAD | Before ( | After ( | |
---|---|---|---|---|---|---|
Total score | T | Anxiety | ||||
C | ||||||
Physical dimension | T | Depression | ||||
C | ||||||
Emotional dimension | T | |||||
C |
LHFQ: Minnesota living with heart failure questionnaire HAD: hospital anxiety and depression scale. T: Training group, C: control group.
(a) Scores of SF-36 in all patients with chronic heart failure and type 2 diabetes mellitus, ■, (
This is the first study to show that aquatic exercise could be used as an effective tool to improve physical function in patients with the combination of CHF and 2DM. Further, the study confirms the results of our previous study with warm water training in elderly patients, supporting that this training is safe for patients with CHF.
A number of studies have demonstrated that exercise training on land, aerobic and resistance exercise improve function in patients with either CHF or with 2DM [
Isokinetic strength in knee extensors was merely significantly improved at 180°/s and not in isokinetic strength at 60°/s or in isokinetic endurance and isometric strength. We have previously been hypothesised that an absent improvement in knee muscle function during aquatic exercise is due to the difficulty to gain enough resistance for this large muscle group in water [
No specific advice concerning diet or diabetic treatment was given during this study. Diabetic therapy was supplied by the patient’s ordinary health care and was not part of the study. A positive finding was the decrease in HbA1c after training. However, other markers of metabolic control did not change. It was not the scope of this study to investigate insulin resistance, and others have shown signs of decreased insulin resistance after exercise in 2DM [
The size of the population in this study was inadequate to show unequivocal changes in quality of life. Of the instruments used, only an index in SF-36, vitality increased after aquatic exercise. Since the level of anxiety and depression was low among most of our patients at baseline no effect was seen in HAD scores.
Aquatic exercise enables a combination of aerobic and resistance exercises and is especially suitable for patients with advanced age, obesity, peripheral neuropathy, orthopaedic problems, or other comorbidity that hampers exercises on land. Due to the buoyancy effect in water weight bearing activities are much more effortless to perform in water [
The rate of adherence in this supervised short-term exercise study was high, which is in accordance with several other studies in patients with CHF [
Similar to many other exercise studies in patients with CHF, our study was performed in a limited number of patients which may restrict external validity. A marked difficulty was to recruit patients that were free from other disabling and complicating disorders like peripheral ulcers, infections, or problems with glycaemic control which are more common in patients with the combination of CHF and 2DM. Further, these patients have a higher morbidity that increases the risk of withdrawal during the study period. In clinical practice, these conditions might temporarily hinder participation in training programmes. However, a temporary stop in the programme should not exclude these patients from the beneficial effects of physical training in the long run.
Aquatic exercise is safe and effective to improve physical and metabolic function in patients with the combination of CHF and 2DM. Whether conventional exercise on land is equally effective has not been shown and would need further studies. Training in water is especially beneficial for those patients with other disabilities that obstruct exercises on land.
This study was supported by the Swedish Heart and Lung Association and the FRF foundation.