|[Index FAC] [FVCC Index]|
Oxygen consumption and ECG response of water-based
versus land-based callisthenics in cardiac patients with
depressed left ventricular function
Cardiac Rehabilitation Center,
BOIS GIBERT, France.
Aquatic callisthenics are widely spread in fitness programs, including cardiac rehabilitation programs. However, cardiac adaptative responses of water-based exercises are poorly documented, especially in heart-failure patients.
The aims of this study are to test the feasibility of water-based callisthenics training in heart-failure patients, and to compare the cardiac and the energetic costs of water-based versus land-based exercise.
Oxygen uptake (VO2) and heart rate (HR) were continuously measured during identical callisthenics sessions, performed on land and in water, in 18 chronic heart failure men (mean age 49 years, mean ejection fraction 27.5±9.5 %), at the beginning and at the end of a 3-week aquatic training program. A cardiopulmonary test was done prior and after rehabilitation.
Aquatic training was appreciated and well tolerated in all patients.
Resting heart rate was lower in water than on land (85.3±13.3 vs 71.1±12.3 p =.003). During upright callisthenics, minimal heart rate and VO2 corresponding to very low intensity movements were similar in both environments, respectively 80.9±15.7 vs 76.1±12.8 beats/min. and 4.49±.7 vs 4.77±0,97 ml/mn/kg -1.
For moderate intensity callisthenics, mean heart rate and peak VO2 were significantly lower in water, respectively 99.2±14.5 vs 93.1±13.3 (p = 0.02), 129.8±20.1 vs 120.5±21.5 (p = 0.009), 18.14±3 vs 13.38±31 (p < .001). These results were still the same at the end of the program.
At stress test, peak VO2 and VO2 at anaerobic threshold showed significant improvement after rehabilitation respectively 22 % (p = 0.006) and 26.6 % (p = 0.03).
Our study shows lower cardiac demand and energetic requirements for moderate intensity callisthenics performed in water versus on land in heart failure patients.
Water exercise training.
Callisthenics and, more recently, moderate resistance training, represent an important component of a comprehensive training program for the rehabilitation of coronary patients, even in the case of depressed left ventricular systolic function [1,2]. Most often, this training consists in land-based exercises, using local or global muscle masses, aimed at improving exercise capacities, muscle function, flexibility and coordination in association with endurance training. The availability of a swimming pool in some cardiac rehabilitation settings offers additional opportunities for exercise, especially for patients with concomitant orthopaedic or neurological problems, obese and elderly patients. Moreover, aquatic training is getting more and more popular in fitness programs and cardiac patients often require counselling for this type of activity.
Despite these facts, many cardiologists are still reluctant to use water-based exercise training in cardiac rehabilitation programs especially in heart-failure (HF) patients, because of the lack of available information, the difficulty of close monitoring and the potential danger due to the hemodynamic changes occurring during water immersion. Hydrostatic pressure exerted by water induces an increase in venous blood return, and therefore a rise in cardiac preload, which may be deleterious in patients with depressed ventricular function.
The aims of this study are to test the feasibility and the safety of water-based callisthenics in a cardiac rehabilitation program, and to compare the cardiac and energetic costs of identical sessions performed either on land or in water in chronic HF patients. Main outcome parameters during exercise sessions are cardiac-related symptoms, ECG-telemetry response and oxygen consumption (VO2). Training effects are assessed via a symptom-limited cardiopulmonary exercise test performed at the beginning and at the end of the cardiac rehabilitation program.
Subjects and method
18 men with chronic HF in NYHA class II-III, mean age 49 years (extremes 32 and 66), enrolled in a cardiac rehabilitation program, volunteered to participate in the study after informed consent. Regional Ethical Committee approved the protocol. Nuclear left ventricular function was less or equal to 40 %. All patients had been stable with regard to symptoms for at least 4 weeks, and were in stable sinusal rhythm. All of them were accustomed to exercising in an aquatic environment. Medications had to remain unchanged throughout the study period. Exclusion criteria were unstable cardiac condition (i.e. unstable angina, complex ventricular arrhythmia, decompensated heart failure), permanent atrial fibrillation, cutaneous infections, fear of water and other disabling diseases that might interfere with the exercise protocol. Demographic and clinical characteristics are shown in table 1.
Table 1: Demographic and clinical characteristics
Cardiac rehabilitation program and training protocol
All patients underwent a 3-week comprehensive cardiac rehabilitation program, combining under medical supervision:
- physical training after completion of a cardiopulmonary exercise testing,
- screening and prevention of risk factors, and educational programs including nutritional counselling, smoking cessation sessions, psychological support and relaxation groups,
- socio-vocational counselling.
The training program consisted in a daily 30-minute endurance session on an ergometric bicycle and a 50-minute aquatic exercise session every day, 5 days a week for 3 weeks.
Endurance training was aimed at a "training heart rate" defined by cardiopulmonary exercise training as the heart rate reached at the anaerobic threshold.
Aquatic callisthenics sessions were performed in upright position at a water height of 1.30 m (approximately armpit water level), at a thermo-neutral temperature of 31°C. They began and concluded with a 5-minute warming up and cooling down period (slow-pace walk, segmental movements at low speed, stretching). The core of the session, about 25 minutes, comprised exercises involving muscle groups of the lower and the upper limbs and torso with progressive increase in intensity (number of repetitions, velocity).
All training sessions were conducted under supervision of a physical therapist and a nurse with monitoring of heart rate by telemetry or pulse meter.
Clinical parameters (chest pain, dyspnea, palpitations, fatigue) and hemodynamic variables (heart rate and blood pressure) were recorded at each session.
Cardiopulmonary exercise testing
At baseline and at the end of the training program, a cardiopulmonary exercise training on a stationary bicycle was performed up to exhaustion using in incremental loading protocol, 10 w/10 w mn -1 (Marquette Case II, Milwaukee Minnesota U.S.A.). Patients were continuously monitored for ECG, and blood pressure measurements were performed every 2 minutes. All the patients were used to the test procedure. Respiratory gas exchange was measured via an Oxycon 4 Analyser (Mijnhardt Odjik, The Netherlands). Oxygen uptake (VO2) and carbon dioxide output (VCO2) were analysed with a sensitive paramagnetic O2 analyser and an infra-red CO2 analyser. VO2 and VCO2 were measured on line every 30 seconds. Prior to each test, the oxygen and carbon dioxide gas analysers were calibrated and the pneumotach was checked with a known volume. The anaerobic threshold was defined at the time where VCO2/VO2 ratio equals 1.
Assessment of cardio-respiratory effects of water-based versus land-based callisthenics sessions
VO2 was measured during identical callisthenics sessions (same type of movements and number of repetitions, same velocity controlled by metronome), performed on land and in water, at the entry and at the end of the rehabilitation process, in order to assess the modifications induced by water immersion and to evaluate the benefits – if any – of physical conditioning. The intensity of the callisthenics sessions varied from mild to moderate, depending on the muscle masses involved and the velocity of the movements (from 20 to 40 b/mn) (cf protocol in appendix).
ECG response to exercise was assessed via telemetry.
For the use of telemetry in water, the transmitter was fitted into a waterproof bag and placed on the back, between the shoulders, in order to keep a good quality of transmission, ECG recording being reliable if the device is kept close to the surface or out of water. Electrodes were also isolated with adhesive foil. The whole device for O2 measurement was kept strictly out of water.
The data were analysed using the computerized Stat View version 5.0 for Windows. All values were expressed as mean±1 S.D.. Paired Student's-test was used to assess differences between land and water exercise groups, and on exercise capacities, before and after rehabilitation. Significance for all tests was set at p < .05.
The training program was well appreciated and tolerated, and no adverse effects were reported during exercise sessions, either on land or in water. Four patients were withdrawn during the study period; 2 of them were called for cardiac transplantation, one was hospitalised because of acute pulmonary oedema occurring independently of an exercise session, and one had a modification of his beta-blockers treatment.
Exercise capacities (table 2)
Maximal exercise capacities increased after completion of the program: 24.6 % increase in maximal workload (p = .0004) and 22.2 % increment in peak VO2 (p = .006). Sub maximal performances improved too, with a 36.5 % (p = .01) and a 26.3 % (p = .03) increase respectively in workload and oxygen consumption at anaerobic threshold. These results are consistent with those observed in other studies dealing with rehabilitation of heart failure patients .
|Table 2: Influence of immersion on heart rate|
Comparison of water versus land-based exercise sessions
Resting heart rate was significantly lower in water than on land, both at the beginning and at the end of the rehabilitation program. The decrease of heart rate occurred immediately after water immersion, and could not be attributable to the "diving reflex" for the head was always kept out of water (table 3).
Table 3: Effects of training on exercise capacities. HR = heart rate AT = anaerobic threshold VO2 = oxygen consumption NS = non significant
During exercise sessions performed at entry on land, heart rate ranged from 80.9±15.7 to 129.8±20.1 beats mn -1, and VO2 from 4.49±0.78 to 18.14±2.99 ml/mn/kg -1 while in water, heart rate varied from 76.1±12.8 to 120.5±21.5 beats/mn and VO2 from 4.17±0.97 to 13.38±3.31 ml/mn/kg -1. Intensity of the session could be considered as mild to moderate (1.3 to 5 mets*).
Minimal heart rate and O2 consumption, corresponding to very low intensity movements, are identical on land and in water whereas mean heart rate, maximal heart rate, and peak exercise O2 consumption are significantly lower in water, respectively 99.2±14.5 vs 93.1±13.3 beats/mn - 1 (p .02), 129.8±20.1 vs 120.5±21.5 beats/mn-1 (p = .009) and 18.14±2.99 vs 13.38±3.31 ml/mn/kg -1 (p < .0001) for exercises of moderate intensity (table 4).
Table 4: Comparison of land-based (LB) vs water-based (WB) callisthenics before and after cardiac rehabilitation. HR = heart rate VO2 = oxygen consumption NS = non significant
These results, indicating a lower cardiac workload and a lesser energetic demand for callisthenics performed in water versus on land, remained the same at the end of the training program.
However, no significant training effects were found during callisthenics after rehabilitation, except a tendency to a decrease in resting and mean heart rate in both environments: this may be due to the short period of exercise training unable to induce significant effects on cardiac heart rate.
Analysis of the subgroups of exercises shows that intensity varies proportionally with the extent of the muscular masses involved and the velocity of the movements. In our study, heart rate and O2 consumption are the highest for global movements involving both upper and inferior limbs, at a pace rate of 40 beats/mn, even though metabolic and cardiac workloads are always lower in aquatic environment (table 5).
|Table 5: Heart rate (HR) and oxygen uptake (VO2) on land (L) and in water (W)/ during callisthenics, before and after rehabilitation.
1 = slow walk; 2 = slow movements of head and torso; 3 = slow movements of upper limbs
4 = slow movements of lower limbs; 5 = fast global movements; 6 = slow abdominal movements
* 1 met = Metabolic Equivalent = 3.5 ml/mn/kg -1
Even if hydrotherapy has been developed in medicine from ancient times in various therapeutic ways, the reports concerning hemodynamic effects of water exercise – especially in cardiac patients – are sparse, sometimes contradictory, and therefore the prescription of water exercise training in cardiac rehabilitation is still debated.
Hemodynamic effects of water immersion and water-exercise
Cardio regulation during water immersion exercise depends on several factors, mainly represented by hydrostatic pressure, water temperature and type of exercise.
Water immersion induces hemodynamic and neuro-humoral regulations: hydrostatic pressure gradient exerted by water induces a cephalad shift of peripheral venous blood and therefore an increase in central blood pressure and in cardiac preload  with a rise in right atrial pressure (+ 12 to + 18 mmHg), in mean pulmonary arterial pressure (+ 9 mmHg) and in cardiac output and stroke volume (+ 32 % to + 79 %). The magnitude of these changes depends on the water height: in upright position, the effects are maximal with water at neck level, inducing a 700 ml increase in intra-thoracic circulation, the greater percentage being in the pulmonary circulation, essentially in the apical regions. The increase in intra pulmonary blood volume and the rise of the diaphragm could explain the reduction of vital capacity (- 8 %) at this water height . Water supine position induces similar hemodynamic changes as immersion to the xyphoïd in upright position.
Elevation of cardiac preload secondary to hydrostatic pressure induces neuro hormonal changes: increase in atrial natriuretic peptide [4,6], less stimulation of renin-angiotensin-aldosteron axis and decreased sympathetic tone, leading to an increase in natriuresis and diuresis. At thermo-neutral temperature, heart rate and blood pressure remain the same or decrease (Franck Starling mechanism, reduction of ortho-sympathetic tone); in our study (air temperature 25°C, water temperature 31°C), resting heart rate significantly lowers at immersion (17.6 % decrease at final assessment).
Water temperature plays also an important role in hemodynamic regulation: at thermo-neutral temperatures, increase in cardiac output and systolic volume is moderate (respectively + 30 % and + 50 %) and heart rate lowers, whereas for higher temperatures (> 39°C), cardiac output is highly elevated (+ 121 %) and pulse rate rises (109±4 beats/min)  parallel to the reduction of peripheral resistance. In this study, water temperature of 31°C can be considered as thermo-neutral for our training program of moderate intensity.
Recently, the effects of thermal hydrotherapy vasodilatation have been tested in coronary and heart failure patients. Tei  in 1995 described the beneficial effects of a 10 minute warm-water bath (41°C) in semi recumbent position in 34 heart-failure patients: cardiac index and stroke index increased and systemic vascular resistance decreased significantly during, but also 30 minutes after warm bathing (p < .01) while mean capillary wedge pressure increased significantly during water immersion, but decreased significantly from the control level after bath. Mitral regurgitation decreased during and after bath compared to baseline values. The authors concluded that thermal vasodilatation could be considered as a new non-pharmacological treatment for heart failure patients, if correctly performed at rest, with water temperature not higher than 41°C, water level below sub clavicular regions and patients in semi recumbency. Michaelsen A. et al  used a home-based European hydrotherapy protocol (according to Kneipp) with peripheral applications of warm and cold water 3 times a day in order to get a prolonged vasodilatation and adaptative response in heart-failure patients: no adverse effects were reported and an improvement in quality of life (p < 0.05), together with a significant reduction in heart-failure-related symptoms, were found.
The type of exercise is also determinant: water resistance depends on the body surface involved in movements but also on the velocity of the movements, which is the main component of resistance, proportional to the square of the speed.
Moreover, exercise in aquatic environment has specific additional advantages, linked to buoyancy, which reduces weight bearing stress on skeletal joints. The decrease of orthostatic pressure is proportional to water height, and buoyancy at shoulder depth is equivalent to a 90 % weight loss, which is of particular interest in obese patients .
That explains why at low speed, exercise seems easier than on land, water being a support, whereas at higher speeds, water resistance may be tremendous and high levels of external workload are required.
So, acute adaptative hemodynamic responses to water exercise are complex and multifactorial: this may explain the apparently conflicting results of clinical studies assessing heart rate, O2 consumption and rate-pressure product of different types of water-based programs.
We will not consider in this study the hemodynamic effects of swimming, which have been already evaluated in coronary patients, confirming the high energetic cost, especially in unskilled patients , equivalent in heart rate, blood pressure lactate and catecholamines to ergometry at 100 watts level. We will focus our comments on studies comparing acute effects of upright water-based and land-based exercise sessions, as in our protocol.
In healthy subjects, water walking at low speed ( £ 3.5 km.h -1), at thermo-neutral temperature with ankle to chest water-depth induces equivalent or lower VO2 consumption and heart rate than on land, whereas for higher speeds (4.5 and 5.5 km.h -1), VO2 consumption, heart rate and rating of Borg scales are higher in water. For jogging activity (8 km.h -1) VO2 consumptions are identical in water and on land [12,13].
Ph. BRECHAT  noticed that water cycling exercise at high level (122 watts during 30 minutes) induces a 25 % higher VO2 than on land, which has to be considered in water immersion rehabilitation programs.
In cardiac populations, to our knowledge, only 3 studies [15,16,17] have compared exercise hemodynamics in water and on land: Lloyd A. and Fernhall B. [15,16] showed no significant differences in heart rate and RPE, the same incidence of ST segment depression in both environments (19 % vs 38 % at exercise test), and a lesser frequency of arrhythmia in water. However, in these studies, the protocols were different on land and in water, and intensity of the sessions was not mentioned.
Mc Murray  compared cardiovascular responses of graduated cycle ergometry exercise (25 w/6'/25w) on land and in water, in 10 coronary patients: he showed that for mild exercise (VO2 less than 1 L/mn -1 or 11.5 ml/mn/kg -1), heart rate, systolic and diastolic blood pressure, were lower in water, cardiac output slightly greater. Total peripheral resistance was significantly reduced in water at all steps of exercise. Mc Murray concluded that exercise in water at low levels of exertion could be more beneficial than on land exercise.
Our study confirms the above results, with a reduced heart rate and O2 uptake in water for identical callisthenics sessions. So, under adequate conditions of temperature and water height, water environment is quite adapted to our population of heart-failure patients in whom cardiac status and deconditioning do not permit high-level intensity of training.
Training effects of water-based exercise programs
Sheldahl LM  has shown that modifications of blood volume distribution during water-based exercise did not alter cardiac adaptation to training: in this study, comparing the effects of aerobic training on cycle ergometers in water and on land in healthy subjects, both groups experienced the same significant increase in maximal O2 consumption (+ 16 % land vs + 14 % water) and similar improvement at a given sub maximal level with decrease in heart rate (- 16 land, - 18 water beats/mn, p < .01) and blood pressure (- 10 mmHg land, - 18 mmHg water) and increase in stroke volume.
In non cardiac older patients, consistent training effects are found concerning aerobic capacities with a 12 % to 20 % increase in peak VO2 and VO2 consumption at ventilatory threshold, but strength and body composition are not changed after water callisthenics program [19,20] unless there is added aquatic resistance training .
Cider  studied the applicability of a land-based callisthenics program with specific reference to exercise capacity, muscle function and quality of life in 25 chronic heart-failure patients (10 controlled group, 15 exercise group): the program was well tolerated, the patients in the hydrotherapy group showed a greater improvement in maximal exercise capacity (+ 6.5 vs – 5.9 watts, p = .001) and muscle function in small muscle groups, together with a significant improvement in quality of life.
In our study, muscle strength was not assessed; global exercise capacities increased significantly after rehabilitation (maximal workload, peak O2 uptake), although it is difficult to assess the relative role of callisthenics or stationary cycle training on these results: at least callisthenics in aquatic environment did not alter negatively maximal exercise capacities. Another study limitation is the short length of time of the program (3 weeks), which may have underestimated the effects of training on neuro-hormonal regulation, as no modifications are shown at rest or at exercise concerning heart rate during callisthenics sessions.
Data concerning the effects of water callisthenics exercise on cardiac function are sparse, involving small numbers of patients, with a wide variety of protocols, and only one publication  deals with heart-failure patients. These facts lead to equivocal conclusions as to the advisability of such a training in cardiac rehabilitation programs, even though aquatic training is becoming more and more popular in several countries.
Our study shows the feasibility and the excellent tolerance of aquatic sessions in heart-failure patients. The intensity of these sessions can be tailored to the patient's possibilities, by adapting water height, velocity of the movements, water temperature, body position and muscular masses involved. In optimal conditions (thermo-neutral water temperature, upright position, chest-height water, mild to moderate intensity of the sessions), heart rate and O2 uptake are lower in water than on land, which is of special interest in deconditioned heart-failure patients.
Further studies are needed to confirm these results and to assess the effects of aquatic callisthenics training programs.
Callisthenics sessions = categories of movements
- standing position with handrail support if needed.
- each movement was repeated 20 times at a pace of 20/mn -1 for slow paced exercises and 40 mn -1 for fast exercises (metronome),
- each session began and ended with a 5 mn period of warm-up and cool-down (slow walk, stretching, breathing exercise),
- slow walking (3 km/H -1 ) forwards, backwards and to the side,
2. Slow movements of head and torso:
- anterior-posterior and lateral flexions of neck,
- lateral flexions of torso.
3. Slow movements of upper limbs:
- arms at side, bilateral shoulder rotation forwards and backwards,
- hands on shoulders, bilateral shoulder rotation forwards and backwards,
- hand on shoulders, lateral elbow extension and flexion,
- hands on shoulders, vertical elbow extension and flexion,
- arms held towards thorax, bilateral elbow flexion,
- arms stretched out at the surface of water in front of the body, bilateral shoulder abduction and adduction,
- breaststroke swimming movements of arms in place,
- arms stretched laterally at the surface of water, backwards and forwards arm rotation.
4. Slow movements of lower limbs:
- bilateral toe flexion and extension,
- reciprocal unilateral heel-lift,
- bilateral heel-lift,
- reciprocal lateral hip abduction,
- standing on one foot with straight leg, lift opposite foot to the knee, hip abduction,
- unilateral knee flexion-extension,
- unilateral knee extension and flexion with hip angle of 45°.
5. Slow movements abdominal muscles:
- arms on handrail, hip flexion (90°) and left and right rotation of lower limbs,
- arms on handrail, hip flexion (90°) then knee extension.
6. Fast global movements:
- jogging in place with high knee and simultaneous arm movements.
We certify that we have seen and approved the paper and that the work has not been, and will not be published elsewhere.
Publication: October 2005
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