SLEEP AND BREATHING—VOL. 4, NO. 4, 2000
ORIGINAL ARTICLE
Physical Exercise as an Adjunct Therapy in Sleep Apnea—An Open Trial VALENTINA GIEBELHAUS, M.D.,* KINGMAN P. STROHL, M.D.,† WERNER LORMES, Ph.D.,‡ MANFRED LEHMANN, M.D.,‡ and NIKOLAUS NETZER, M.D.‡ ABSTRACT Background: The aim of this study was to determine in an open trial if physical exercise in sleep apnea patients is safe and/or influences respiratory disturbance index (RDI). Methods: After being treated 3 months or more with nasal CPAP for moderate to severe sleep apnea syndrome, eleven patients (1 female, 10 male, mean age 52.2 years) began a six-month period of supervised physical exercise twice a week, 2 hours each time. Before and after this period a Polysomnography without CPAP was recorded, along with a bicycle exercise test with lactate profile, echocardiography, body-weight, and body-height measurement. Results: No adverse effects or cardiopulmonary problems were observed. There was no significant change in body weight with physical training; no significant difference in either min SaO2 nor mean SaO2; and no significant improvement in fitness. No adverse cardiopulmonary effects or problems were observed. There was a decrease of the RDI from 32.8 to 23.6 (p < 0.05), without a significant change in the REM-sleep portion of total sleep time (TST), NREM sleep, or TST. Conclusions: A prescription for mild to moderate exercise is safe in the management of sleep apnea, and, even in the absence of a fitness improvement, there occurred a decrease in RDI without a change in sleep architecture. KEYWORDS: sleep apnea syndromes, physical exercise, sleep
Is regular physical exercise of benefit in the treatment of sleep apnea syndrome (SAS)? To our knowledge, there are no data on this subject. There are, of course, known positive effects of a significant weight reduction,1–3 and exercise is assumed to be part of this regimen. It is also stated that, despite body weight reduction, many patients still cannot do without nCPAP.4 A possible positive effect of regular physical exercise alone could result, however, from an increased overall tone of the skeletal muscles, including the pharyngeal muscles.5 There could be positive effects on the drive to breathing by regular aerobic and anaerobic ex-
Preliminary data from this investigation and a part of the figures were previously published in German in Pneumologie 1997;51(Suppl 3):779–782 *Pulmonary Division, Department of Medicine, University Hospitals Freiburg, Freiburg, Germany; †Department of Medicine, Division of Pulmonary and Critical Care Medicine, Sleep Disorders Research and Education Center, Case Western Reserve University, Cleveland, Ohio, USA; ‡Department of Medicine, Division of Sportsmedicine, University Ulm, Germany Reprint requests: Dr. Kingman P. Strohl, Div. Pulm. and Crit. Care Med., Dept. Medicine, Case Western Reserve Univ., VA. Medical Center 111 J (W), 10701 East Boulevard, Cleveland, OH 44106. E-mail:
[email protected]
ercise.6–9 However, there is also the potential for adverse effects in suggesting exercise to patients with SAS in whom there may also co-exist risk factors for cardiac disease.10 The aim of this study was to determine the safety and efficacy of exercise in patients with treated sleep apnea in an open trial. The regimen alternated aerobic exercise with stamina power exercise under supervision by a sports therapist for a 6-month period of time. Results indicate that this regimen is safe and is associated with a decrease in apneic activity in the absence of changes in weight or in sleep architecture.
PATIENTS AND METHODS The study group was comprised of 13 patients with moderate to severe sleep apnea syndrome (moderate or severe sleepiness with an RDI > 10, SaO2 min < 85%) who were treated with nasal CPAP (3 to 12 months) with objective reduction in RDI and symptomatic improvement. Eleven patients (1 female, 10 male; average age 53.8 years; see Table 1) completed the program, while 2 patients did not participate in follow-up studies because of private and/or occupational reasons. All
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SLEEP AND BREATHING—VOL. 4, NO. 4, 2000 TABLE 1. Characteristics of the 11 Patients Who Participated in the Study and Were Included in the Final Examination
Patient ID (m/f) 1 (m) 2 (m) 3 (m) 4 (m) 5 (m) 6 (m) 7 (m) 8 (m) 9 (m) 10 (m) 11 (f)
Age (years)
BMI (kg/m2)
Baseline RDI CPAP at Start of Study
48 55 54 49 62 39 47 55 52 57 56
24.2 32.7 23.6 26.2 25.0 31.5 27.3 25.2 26.6 32.8 27.2
52 11 33 11 26 32 20 20 81 58 17
SaO2 Minimum at Start of Study
Time on CPAP Treatment (Months at Start of Study
78% 84% 79% 84% 74% 77% 82% 79% 76% 77% 81%
7 4 9 4 6 8 3 4 12 4 5
BMI, body mass index, Kg/m2; RDI, respiratory disturbance index, events/hour of sleep; m, male; f, female.
individuals had formed a sports group, with the costs for the exercise site and for the instructors sponsored by public health insurance. To be eligible to form such a group, patients had to indicate a willingness to regularly attend the sessions, and to have no history of adverse cardiac risk (angina, severe arrythmias, uncontrolled hypertension, or echocardiographic evidence of right ventricular enlargement or reduced left ventricular ejection fraction). The patients gave written consent for the additional polysomnography and exercise studies that were performed before and after the 6-month exercise program. Under the observation of specially trained sports teachers, the group performed a 2-hour aerobic exercise program (jogging, games, and gymnastics) once per week and a second 2-hour program of power exercise (repetitive light weight-lifting) once per week. The aerobic exercises were based on a coronary rehabilitation model with a maximum performance set at 150 watt (W) based upon age, body mass index (BMI) and training experience. Power exercises were adapted to individual physical capabilities. Prior to the start of the 6-month exercise period, the patients were examined by 12-channel standard polysomnography (Jaeger/CNS Sleep Lab), including breathing parameters, SaO2 mean (average oxygen saturation), and SaO2 basal (basal oxygen saturation). Determination of obstructive and central apneas, as well as obstructive hypopneas, in all 12 patients was done using the following criteria: 1) apnea was defined as an absence of inspiratory flow for at least 10 seconds; 2) central apneas were defined as total absence of nasal and oral inspiratory flow and chest/abdominal movement during the period of absence of inspiratory flow; 3) obstructive apneas were de-
fined by a decrease of greater than 80% in airflow in the presence of paradoxical movements of the ribcage and abdomen; 4) obstructive hypopneas were defined as a 50 to 80% reduction in airflow accompanied by desynchrony of ribcage and abdominal motion; and 5) RDI was defined as number of obstructive and central apneas and obstructive hypopneas per hour. The sleep parameters were assessed according to Rechtschaffen and Kales criteria,11 included REM-sleep phases (REM), non-REM sleep phases, and total sleep time (TST). A day after the polysomnographic examination, the patients underwent bicycle ergometry testing (beginning at 25 W or 50 W and increasing in 50 W steps of 3 min each) with lactate performance profile. Further, they had echocardiography (assessment of ventricle size and left ventricular function) together with determination of body weight and height. For evaluation of functional capacity, a performance value (watt and heart frequency) at 4 mmol lactate (whole blood) on the lactate capacity profile was taken as an index of functional capacity. This value has been denoted as pLA 4 mmol. The statistic evaluation of the results was done by Wilcoxon signed rank test for paired data.
RESULTS None of the subjects experienced health problems or cardiorespiratory incidents (including chest pain or significant exercise induced hypertension) during or after exercise. The 11 subjects who completed all the studies attended 80% of all sessions. The patients’ body parameters (height and weight) had not altered significantly during the exercise period. The average weight of all patients was 79.72 kg before and 80.36 kg at the end of the six-month program (Fig. 1). Lactate profiles of 9 of 11 patients were evaluable, while the samples of 2 patients could not be analyzed. The parameters for exercise performance did not change (Fig. 2). The blood pressure profile after the exercise test was the same before and after the exercise program. The RDI showed a significant difference between the tests before and after the 6-month period of exercises (average RDI before exercise: 32.8/h, average RDI after exercise: 23.6/h; p < 0.05 [Fig. 3]). Oxygen saturation did not change significantly, either SaO2 mean or SaO2 min, from the beginning of the sports period to its end (SaO2 mean: before exercise = 91.8%, after exercise = 92.4%, n.s.; SaO2 min: before exercise = 79.2%, after exercise = 81.7%, n.s.). The REM-sleep phase portion of TST did not change significantly (mean REM before exercise: 16.9%, mean REM after exercise 17.1%, n.s). Neither was there a significant difference in NREM sleep or TST. Neither positive nor negative correlations could be established between alterations of RDI and of pLA 4 mmol. There were no correlations either between the al-
EXERCISE AND SLEEP APNEA—GIEBELHAUS ET AL.
FIG. 1. Body weight (kg) difference, nonsignificant (Test 1, measurements before the 6-month period of physical exercises, Test 2, after the 6-month period of exercises; Id, patients’ number according to Table 1: patient numbers 6 and 7 were not included in the final examination).
terations of body weight and pLA 4 mmol, and between alterations of body weight and the RDI.
DISCUSSION This open trial study indicates that a mild exercise program, sustained for 6 months, is safe and was well tolerated by the individuals with treated sleep apnea. We
FIG. 2. Serous lactate difference as indicator for physical performance, pLA 4 mmol, measured in watts, nonsignificant (See legend for Figure 1; lactate profiles of patients numbers 3 and 5 were not evaluable).
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FIG. 3. Difference of RDI (Respiratory Disturbance Index), p < 0.05. (See legend for Figure 1).
chose to study patients who were already on effective therapy in order to reduce potentially confounding influences of illness on exercise effects. This approach has the advantage of isolating the exercise effect. The average decrease in RDI of almost 30% could not be attributed to a change in body weight or BMI. Whether this regimen can be considered as primary therapy will require an experimental design that either controls for these variables by matching, or by enrolling sufficient numbers of patients to statistically examine for the effects of sleepiness and sleep hypoxemia. The effects could be influenced by the CPAP-therapy itself, as the numbers of apneas decrease in 6 months on CPAP alone3,12; however, we believe this effect to be unlikely as all patients had been in adequate treatment for at least 3 months prior to the exercise program. Remarkable changes in oxygen saturation parameters were not observed, but patients in the group were in reasonably good health, without cardiovascular compromise as assessed by echocardiography. No remarkable changes in sleep parameters were observed; mainly, no change in REM or NREM amounts were noted, which could have explained an improvement in RDI. Exercise can alter physical fitness and sympathetic tone.5 Exercise capacity varied among patients, but a total physical strain of 2 training hours twice a week is not sufficient for a significant change in lactate levels.13 Therefore, we cannot attribute the effect to a general increase in cardiovascular fitness. An improved drive to breath has been observed in training studies;6–9 however, those studies were performed in healthy subjects. Future studies, therefore, should aim at measuring ventilatory drive in addition
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to polysomnographic records. From experiments with dogs, it is known that stimulation of the gastrocnemious muscle and sciatic nerve afferents lead to an increased tonus of the genioglossous muscle.14 Therefore, another possibility is that the pharyngeal and glossal muscles were engaged during training, a possibility suggested by the use of an exercise training method for people with tongue muscle weakness and impairment.15 In summary, an exercise program for patients with sleep apnea syndrome can be safely instituted and accompanied by a reduction in apneic activity. While exercise is thought of as an adjunct to more definitive therapy, it may move to a more primary role in the management of lesser forms of illness.
ACKNOWLEDGMENTS This investigation was partially supported by German public health insurances (Gesetzliche Krankenkassen). We wish to thank our colleagues in the Department of Sports Medicine and Preventive Medicine at the University of Freiburg, especially Josef Keul, Martin Halle, and Alois Berg for their assistance, and the Department of Sports Medicine and Rehabilitation at the University in Ulm, which supported us in this investigation.
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