R e s e a r c h A r t i c l e T h e E f f e c t o f L o w e r L im b P a s s i v e M o v e m e n t o n L u n g F u n c t i o n A B S T R A C T : T h is s tu d y e x a m in e d th e e ffe c ts o f a n k le p a s s iv e m o v e m e n t o n lu n g f u n c tio n in h e a lth y a d u lts. A p r e -te s t p o s t- te s t e x p e r im e n ta l d e s ig n w a s used . P a s s iv e p la n ta r a n d d o r s ifle x io n o f th e a n k le w ere p e r fo r m e d at 6 0 r e p e titio n s p e r m in u te o n 6 0 h e a lth y s u b je c ts in th e s u p in e p o s itio n . L u n g fu n c tio n a t r e st w a s c o m p a r e d to th a t d u r in g p a s s iv e m o v e m e n ts. The re su lts in d ic a te d th a t a ll m e a s u r e d p a r a m e te r s in c lu d in g th e b re a th in g fr e q u e n c y , tid a l v o lu m e , m in u te v e n tila tio n , o x y g e n c o n s u m p tio n a n d c a rb o n d io x id e o u tp u t, in c r e a s e d s ig n ific a n tly d u r in g p a s s iv e m o v e m e n ts a s c o m p a r e d to th o s e a t rest. T h e a u th o r s c o n c lu d e th a t p a s s iv e m o v e m e n ts e lic it a s ig n ific a n t v e n tila to ry in crea se in h e a lth y h u m a n su b jects. The e ffe c t o f p a s s iv e m o v e m e n ts in th e tr e a tm e n t o f u n c o n s c io u s o r d is e a s e d in d iv id u a ls s h o u ld b e in v e stig a te d . K E Y W O R D S : P A S S IV E M O V E M E N T , M I N U T E V E N T IL A T IO N , C U T A N E O U S S T IM U L A T IO N , B R E A T H IN G F R E Q U E N C Y , T ID A L V O L U M E . NARAIN S ’, LIN J2, PUCKREE T3; 1 Addington Hospital, Kwa-Zulu Natal, South Africa Department of Biochemistry and Microbiology, University of Zululand, Private Bag X1001, Kwa Diangezwa 3886, South Africa Department of Physiotherapy, University of Durban-Westville, South Africa INTRODUCTION Passive movem ents are com m only used by physiotherapists to improve or m ain­ tain the circulation in paralysed co n ­ scious or unconscious patients (Kisner and Colby, 1990a). The range o f motion of the joints and length o f soft structures are also maintained or increased through the use o f this technique. Anecdotal inform ation relating to the effects of passive movem ents as described above is readily available and well known. H ow ever the effects o f passive m ove­ m ents in enhancing lung function in either conscious or unconscious patients is not known. The effects o f active exercise on lung function have been well documented (C o m ro e e ta l, 1943; Dejours et al, 1959; Ishida et al, 1993 and Jensen, 1972). Jensen (1972) showed that within 20 seconds o f voluntary exercise, the tran­ sient ventilatory responses during arm work were greater than those during legwork. O ther researchers (Davies and Sargeant, 1974; Sawka, 1986 and Celli et al, 1988) reported that the accessory inspiratory m uscles becam e activated when the upper torso and arm were posi­ tioned during the unsupported arm exer­ cise and caused a change in ventilation. Gozal (1996) demonstrated that lower limb motion induced by passive back­ ward pedaling elicited a significant and sustained ventilatory increase in healthy children. Furthermore upper body motion associated with rhythm ic sw aying o f the lower extremities has been implicated in the ventilatory response to exercise. Ishida et al (1993) also reported an increase in the minute ventilation o f hum ans at the onset o f passive leg m ovem ents during sleep. H ajek and M ader (1990) found that oxygen con­ sumption was increased during active movem ents, yet it was reduced during passive movements. T he effects o f p h y sio th erap eu tic passive movem ents on lung function have not been systematically investigated. The purpose o f the present study was to determ ine the effects o f passive m ovements on selected lung function variables. METHODS This study was approved by the Ethics Com m ittee of the U niversity o f Durban- Westville. Sixty healthy non-smoking male and female volunteers from the U n iversity cam pus particip ated by voluntary inform ed consent. Subjects had no history o f cardiopulm onary or neurom uscular disease, and sensation over the jo in ts (pro p rio cep tio n and cutaneous) where passive m ovements were applied was intact. Each subject was told about the experimental proce­ dure in detail but was not acquainted with the purpose o f the experiment. Measurements Tidal volume (Vt), breathing frequency (Fb), minute ventilation (V e), oxygen consum ption (VO2) and carbon dioxide (VCO2) output were m easured using the M etaM ax mask and volume transducer Triple-V® (Cortex M etaM ax, Portable Test System; Biophysik GmgH - M odel SBS). A N ation® tube was used to guarantee a constant humidity during measurements. The pneum otachom eter was calibrated using a 3-litre calibration syringe. All data was stored on the Cortex M etaM ax logger and analyzed on computer. Procedure Each subject was allowed to rest in supine for 2 minutes before the actual main experim ent was perform ed. The Cortex M etam ax mask was applied. The pulm onary variables were m onitored for 2 minutes at rest and for 2 minutes with the researcher’s hands placed on the right foot (cutaneous stimulation). CO RRESPO ND ENCE TO: Dr. T. Puckree Department o f Physiotherapy University of Durban-W estville Private Bag X 54001 South Africa Tel: 27-31-2044817 Email: lpuckree@ pixie.udw.ac.za SA J o u r n a l o f P h y s io th e ra p y 2001 V o l 57 No 2 7 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) mailto:lpuckree@pixie.udw.ac.za FIGURE 1. Mean and standard deviation of breathing frequency at rest, during cutaneous stimulation and passive movements (n=60), * indicates significant difference (p< 0.05) compared to rest. FIGURE 2. Mean and standard deviation of tidal volume at rest, during cutaneous stimulation and passive movements (n=60), * indicates significant difference (p< 0.05) compared to rest. # Indicates significant difference (p< 0.05) compared to cutaneous stimulation. C uta neou s s tim u la tio n 1--------- ---------------------- 1 Passive m ovem ents Passive plantar and dorsiflexion o f the right ankle jo in t (K isner and Colby, 1990b) were perform ed in supine lying subjects for 2 m inutes at 60 rpm. Subjects were instructed to relax and not to resist the m otion or actively partici­ pate in it. Care was taken to support the body as much as possible to avoid voluntary contractions and m otion arti­ facts. In addition traction or compression was not applied either on the ten d o - Achilles o r the ankle joint. All m ove­ ments com m enced with dorsiflexion. In order to m inim ize error passive m ove­ ments were applied to all subjects by the same investigator. The Cortex M etam ax autom atically saved data in the logger for every 10 seconds. Data Analysis The data was tran sferred from the M etam ax logger onto a computer. The analogue data o f each variable for each subject were then reduced to a quanti­ tative form using the Cortex M etamax software. M ean and standard deviation o f the quantified data were calculated. Statistical com parisons w ere applied using the paired t-test. The probability was set at 0.05. RESULTS Sixty healthy subjects, 19 male and 41 fem ale subjects, aged 18 to 30 years; height 152-179 cm; body mass, 45-80 kg, participated in this study. The data from all subjects were considered usable. None o f the m easured param eters showed any significant difference across gender. Figure 1 shows a significant increase (28,7% ) in breathing frequency from rest to when the passive m ovements were applied. Response to the cutaneous stim ulation was also significantly differ­ ent from those at rest (14,5% ). There was no significant difference between the responses to the cutaneous stim ula­ tion and when the passive m ovements were applied. As shown in Figures 2 and 3, both tidal volum e (Vt) and minute ventilation (Ve) showed significant increases during the cutaneous stim ulation (15,0% and 17,2% respectively) and during passive m ovem ent (20,5% and 34,7% respec­ tively) as com pared to rest. Responses to the cutaneous stim ulation w ere also significantly different com pared to that during passive movement. Both O 2 consum ption and CO 2 out­ put were significantly increased by both passive movem ents (10,5% and 29,3% respectively) and the cutaneous stim u­ lation (9,3% and 18,5% respectively) as com pared to rest (Figures 4 and 5). There was a significant difference in C O 2 output but not in O 2 consum ption during passive m ovem ent as com pared to the cutaneous stimulation. DISCUSSION: In the present study the authors attempted to com pare the changes in lung function at rest to those during the cutaneous 8 SA J o u r n a l o f P h y s io th e ra p y 2001 V o l 57 No 2 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) FIGURE 3. Mean and standard deviation of Minute Ventilation at rest, during cutaneous stimulation and passive movements (n=60), * indicates significant difference (p< 0.05) compared to rest. # Indicates significant difference (p< 0.05) compared to cutaneous stimulation. FIGURE 4. Mean and standard deviation of Oxygen Consumption at rest, during cutaneous stimulation and passive movements (n=60), * indicates significant difference (p< 0.05) compared to rest. stimulation and passive m ovem ent of the ankle. B reathing frequency (Fb), tidal volum e (Vt), minute ventilation (Ve), oxygen consum ption and C O 2 outputs increased significantly during passive movem ents as well as the cuta­ neous stimulation com pared to the rest phase, with no significant difference in the above pulm onary variables among different genders. A lthough both cuta­ neous stimulation and passive m ove­ ments increased all m easured pulmonary variables, there were significant differ­ ences (increases) in Vt, Ve and CO 2 outputs during the passive m ovements com pared to cutaneous stimulation. The findings of this study are in accordance with those o f previous inves­ tigations (Waisbren el al, 1990; Ishida et al, 1993)). W aisbren et al, (1990) suggested that a rapid increase in venti­ lation at the onset o f passive m ovem ent is a true hyperventilation and that stim u­ lation o f the joints can be a significant contributor. Ishida et al (1993) also found an increase in ventilation at the onset o f passive m ovem ent during sleep and the activity o f the cerebral cortex decreased m ore during wakefulness. These results suggested the existence o f neural inhibi­ tion from the higher centers to the respi­ ratory center during wakefulness. It is possible that the respiratory center is stim ulated by afferent inputs from m ov­ ing limbs and sim ultaneously modified by inhibitory and/or facilitatory signals from higher centers so that ventilation might increase at the start o f locom otion/ passiv e m ovem ents. A fferen t drive from m oving limbs could also produce increases in ventilation w ithout any change in cardiac output. Increased ventilation accom panies m otion in anim als (C om roe et al, 1943) and h u m an s (D e jo u rs el al, 1959; Jaeg er-D en av it el al, 1973). T hese observations led to a theory that the early reflex h y p erp n ea o f exercise, w hich o riginates in the c o n tractin g m uscle and/or surrounding supportive tissues, is either totally or predom inantly m ediated by a neural m echanism that affects the respiratory control centers via spinal afferent pathw ays (Com roe el al, 1959; Flandrois et al, 1967; Harrison et al, 1932). If passive m ovem ents facilitate afferent inputs to the respiratory control centers as su g gested by previous investigators it is likely that the ventila­ tory responses observed during passive movem ents o f even a single jo in t in this study closely ap proaches the reflex hyperpnea that occurs during the onset o f active exercise. Passive m ovem ents o f the low er limbs preferentially involve mechano- recep to r feed b ack m echanism s w ith ­ out activation o f feed-forw ard centers (Eldridge et al, 1991; W aldrop et al, 1989; Gozal et al, 1996). These observa­ tions suggest that peripheral afferent pathways activated by passive motion alone, that is, with no feed-forw ard input and minimal m etabolic increases, would be associated with significant ventilatory SA J o u r n a l o f P h y s io th e ra p y 2001 V o l 57 No 2 9 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) FIGURE 5. Mean and standard deviation of Carbon-di-oxide output at rest, during cutaneous stimulation and passive movements (n=60), * indicates significant difference (p< 0.05) compared to rest. # Indicates significant difference (p< 0.05) compared to cutaneous stimulation. responses by eliciting the activation o f m echanoreceptors in the low er limbs. B rice et al (1988) elucidated the essential role o f peripheral neural feed­ back m echanism s in m otion-induced ventilatory increases. Passive movements o f low er extrem ities in hum ans with clinically com plete spinal lesions did not elicit increases in m inute ventilation. In the present study all subjects had in tact cu tan eo u s and p ro p rio cep tiv e sensations. The finding o f a significant increase in all ventilatory param eters from rest to cu tan eo u s stim ulations confirm s the significance o f peripheral neural feedback from cutaneous and static jo in t receptors. The significant increases in just Vt, V e and VC O 2 during passive m ovem ents com pared to cuta­ neous stim ulation could be attributed to additional input from dynam ic jo in t proprioceptors during the m ovem ent. The observed responses in conscious subjects may be due to activation o f m echanoreceptors (feedback) and to centra] com m and (feed-forward). This study focussed on the effects o f relaxed passive m ovem ents of the ankle only on healthy young, conscious subjects. Therefore the results cannot be extrapolated to patients. H ow ever the results can serve as a com parison for future studies on a wide range o f normal and patient populations for exam ple geriatrics, postoperative patients, uncon­ scious patients, hem iplegic patients and patients with chronic chest diseases. In summary passive movem ents o f the ankle in healthy subjects elicit a significant increase in Fb, Vt, Ve, O 2 consum ption as well as CO 2 output. The passive-m ovem ent effects were observed at a passive m ovem ent frequency o f 60rpm in awake humans. These findings could have value during the use o f passive m ovem ents to elicit a significant ventilatory increase in conscious sub­ jects. The effects of therapeutic passive movements o f other joints and com ­ b ination o f jo in ts in norm al and diseased or injured persons needs fur­ ther investigation. 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