[A new procedure for the estimation of physical fitness of patients during clinical rehabilitation using the 6-minute-walk-test].
AIMS OF THE INVESTIGATION: The 6-minute-walk-test (6-MW) is an effective tool for measuring physical fitness in elderly patients. The increased walking distance is taken as a parameter for improved physical conditions. Frequently an unaltered walking distance is found after clinical treatment, but heart rate is significantly lower in the second challenge, indicating an improved physical fitness. This positive effect is not recognised when only the walking distance is analysed.


METHODS
An analysis of the 6-MW test was performed on 263 patients before and after 3 - 4 weeks clinical rehabilitation. In a control group of 26 patients 6-MW was repeated after recovery at the beginning and the end of the clinical treatment. Instrumented by a mobile pulse oximeter for recording oxygen saturation and heart rate, patients were instructed to walk as fast as they can do during 6 minutes. Measurements were performed every 30 seconds and printed out. Two new parameters, efficiency (E = S/f (C)), the ratio of distance and mean heart rate, and the theoretical increase in walking distance (S (z) = Delta f (C1)/Delta f (C2) x S (2) - S (1)) were introduced and tested. S (z) = theoretical increase in distance, Delta f (C1) = difference in heart rate at rest and mean heart rate at steady state during the first walk test with distance, S1. Delta f (C2), and S2 are measured during the second walk. Thus, the increase in distance is calculated under the assumption that the second walk test would have been performed by the patient with the same difference in heart rate that he/she achieved in the first walk.


RESULTS
The patient groups walked 353 +/- 80 m at 106 +/- 14.3 beats/min in the 1st. 6-MW and 368 +/- 76.9 m at a heart rate of 105 +/- 14.0 beats/min in the final test. The increase of the walking distance was most significant in patients with shorter distances in the 1st 6-MW. A significant increase in the walking distance and in efficiency was found in patients with shorter walking distances or lower heart rates in the final test, using the numerical procedure described above.


CONCLUSIONS
The patient's performance of the second walk test with an unchanged distance at a lower heart rate reveals an improved physical fitness. This is solely described by an increase by the parameter of efficiency, E. The calculation of the parameter, Sz, theoretical difference in walking distance (i. e., theoretical increase in almost all tests) provides a quantification of the effect of exercise training, even if the patient is not cooperative during the tests. Both parameters have proved to be suitable estimations for the assessment of physical fitness as a beneficial effect of clinical rehabilitation.
Marek
W
W
Institut für Arbeitsphysiologie an der Augusta-Kranken-Anstalt, Bochum. Wolfgang.Marek@ruhr-uni-bochum.de
Marek
E
E
Vogel
P
P
Mückenhoff
K
K
Kotschy-Lang
N
N
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006233:Persons with Disabilities / Q000534:rehabilitation*; D004562:Electrocardiography / Q000379:methods; D004734:Energy Metabolism; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D010808:Physical Examination / Q000379:methods*; D010809:Physical Fitness; D013647:Task Performance and Analysis; D016896:Treatment Outcome