Acta Med Scand 205: 257-262, 1979
Temperature Regulation in Anorexia Nervosa Patients during Prolonged Exercise C. T. M. Davies,’ L. Fohlin and C. Thoren From the Depurtment of Pediutrics and the Lubortitor>>of Clinicul Physiology, St. Giiran’s Children’s Hospitul, Stockholm, Sweden
ABSTRACT. The thermal responses to prolonged exercise on a stationary bicycle ergometer have been studied in 10 anorexia nervosa (AN) patients and 5 normal subjects. The patients were young (12-18 years) females (except for 1 case) and had less than 10% of their body weight as fat. The basic experiments were conducted in a moderate environment (24°C)at approximately 65 % maximal aerobic power output on all patients and controls. In addition, 2 patients were studied in warm (32°C) conditions, 1 patient in cool (12°C) conditions and 2 patients after being heated for 30 min in a sauna at a temperature of approximately 50°C. Measurements included oxygen uptake, metabolic (M) and total heat production, evaporative sweat loss (E), rectal (Tre)and mean skin temperatures. The results showed that T,, (for a given M) was higher and E lower in the patients than the controls. Passively heating the anorexia patients hefore exercise increased resting T,, and E but did not affect the “plateau” value of TrFobtained at the end of work. In the warm environment, T,, rose to the same level as observed at 24°C but did not rise atmve the resting value in cool conditions. Thus it ,would appear that although patients with AN can regulate their body temperature adequately in a moderate environment, loss of body fat which reduces thermal insulation may decrease the range of ambient temperatures over which T,, can be maintained during exercise. Our data do not‘ support the theory of a loss of central (hypothalamic) thermoregulatory control in anorexia.
show signs of vitamin, iron or protein deficiency diseases. One of the major physical concerns of the patients is a feeling of cold, particularly in the extremities. Their hands and feet even in a thermally neutral environment are vasoconstricted, acrocyanosed and give rise to a feeling of numbness and sometimes pain. It is surprising therefore that although low body temperatures and hypothermia (22) have often been reported in AN, few attempts have been made to study thermoregulation in this disease. Wakeling and Russel (21) have reported the effects of a localized peripheral heat stress, induced by placing the arm up to the elbow in water at 4S”C, on oral and finger temperatures in 11 anorexic girls. Gleeson and Moore (10) have studied the effects of mild heat and Mecklenburg et al. (14) of cold stress in a climatic chamber on 5 anorexia nervosa patients. To our knowledge, no attempt has been made to study the thermoregulatory responses t o a given metabolic heat load resulting from exercise in AN. The present investigation examines metabolic and thermal responses to prolonged work in 10 patients with AN and 5 healthy normal subjects. SUBJECTS A N D METHODS The patients formed part of a larger study ( 8 , 9). They conformed to the following criteria for AN, chiefly accord-
Key words: anorexia nervosa. temperature regulation,
prolonged exercise, rectal temperature, skin temperature, sweat loss. Acta Med Scand 205: 2.57. 1979.
’ On leave of absence from the Medical Research Council, Environmental Physiology Unit, London School of Hygiene & Tropical Medicine. London. England.
Primary anorexia nervosa (AN) is universally characterized by weight loss due to a failure to eat (3, 5). The physical features of AN are those of chronic inanition; the patients are often extremely emaciated with pallid and sallow skin but rarely
Abbreviations: AN=anorexia nervosa, Vo,=oxygen uptake, V,,2 max = maximal aerobic power, rlP= rectal temperature, T,k = skin temperature, = mean temperature, M = metabolic heat production, H = total heat production, E = evaporative sweat loss, S = heat storage, T,,,,= dry temperature, T,,, = wet temperature, C = convection. R = radiation.
17 7929x4
258
C. T. M . Duvies et al.
Table I . Physicul c/~crrrrc~tr~istic~,s of' the p t i e n t s cind controls (mean f I S.D.) Ht=height, Wt=weight, LBM=lean body mass Ht (cm)
(v.) Patients (n=IO) Controls
15.0 f2.0 14.9 t3.1
(n=5)
164
Wt
LBM
Vc,,max
(kg)
(kg)
(I/iin)
34.1 f7.2
1.18 t0.30 2.30 k0.47
I
37.9
&I5
t8.1
166 +I4
48.9 212.9
I
ing to Dally ( 5 ) : I ) Age at onset less than 25 years. 2) Active refusal to eat with accompanying pronounced weight loss. 3 ) No evidence of schizophrenia, severe depression or organic diseases. The physical characteristics of the patients with A N and the healthy controls are given in Table I. The anorexic state of the patients had lasted on average for 1.0 year (range 0.5-3 ) prior to the investigation. The normal menstruation and ovulatory cycles had ceased in the female patients at the time of measurement. They were studied at rest and during work on an electrically braked bicycle ergometer at approximately 65 % of their maximal aerobic power (Vo2max) for I hour. The subjects were weighed nude before and immediately after exercise, on a balance accurate to t 10 g. Rectal temperature ( T J was measured during exercise from a thermocouple inserted into the rectum 8 cm above the internal sphincter. Skin temperature (T&) was measured at 14 sites, finger and thumb,
hand, upper and lower arm, forehead, pectoral, sternum, abdomen, scapular, lumbar, anterior and posterior thigh and anterior and posterior calf, at rest and during the 2nd, Xth, 2Oth, 30th, 40th, 50th and 60th min of exercise using a thermistor probe mounted on an applicator. The recordings (except finger and thumb measurement) were weighted after the method of Hardy and Dubois (11). and the average was taken as the mean body skin temperature (Tqk). Oxygen uptake (vjoz) was measured at rest and during the 28-30th and 5840th min of exercise by the open circuit (Douglas bag) technique, Opand COPcontent of expired air being determined by the micro-Schokander technique. Heart rate was calculated from standard ECG recordings at rest and every 2 min during exercise. From the raw data, calculations of metabolic ( M ) and total heat ( H ) production, evaporative sweat loss ( E ) and heat storage (S)were made using standard equations (15). Dry (Tdh)and wet (TwJ temperatures in the laboratory were 23.6k0.84 and 14.lf2.2"C, respectively. In two patients the experiments were repeated with and without preheating. For this purpose the patients sat in a sauna for 30 min at about 50°C T,lband 26°C T,,, prior to exercise. In addition, two patients performed exercise at an elevated environmental temperature (Tdb 32.2k0.4, Twb=1 7 . 6 t 1.40"C) and one patient worked in a cool environment (T,,,, 11.7k0.4, Twb6.4kO.S"C). Control experiments were conducted on 4 healthy boys and one healthy girl (Table I) in the laboratory and 2 healthy boys in the cool and warm environments. V o , max was measured in the patients and control subjects on separate occasions. For reasons previously given and discussed (8) it was impossible to establish with abso-
Table 11. Thermoregulatory responses to exercise oj ' A N patients and controls (mean fS.D.)
12°C Patients (n=I)
1.31
73
90
447
357
36.58
30.09
36.80
29.10
3
Controls (n=?)
1.88
58
I40
64 I
508
37.10
30.98
38.40
28.94
153
270 215 i6h +so 548*** 432 +I32 +I00
36.60 t0.56
3 1.68 t0.73
38.07 k0.51
32.18 k1.15
54 t35
37.22**
to.19
32.11 k0.64
38.36 k0.36
31.30 k0.61
k69
24°C Pati en t s (n=IO) Controls (n=5)
0.78 66 t0.20 +I0 1.61*** 64 f0.39 fX
54
i I7 Il6*** t32
267***
24°C with preheating Patients (n=2) 32°C Patients (n=2)
1.07
68
80
363
298
36.75
33.43
38.40
32.60
1 12
0.91
56
75
311
236
36.55
33.19
38.25
35.84
136
Controls (n=2)
1.78
62
123
607
484
37.70
33.75
38.40
33.46
415
***p
Temperature Regulation in Anorexia Nervosa Patients during Prolonged Exercise C. T. M. Davies,’ L. Fohlin and C. Thoren From the Depurtment of Pediutrics and the Lubortitor>>of Clinicul Physiology, St. Giiran’s Children’s Hospitul, Stockholm, Sweden
ABSTRACT. The thermal responses to prolonged exercise on a stationary bicycle ergometer have been studied in 10 anorexia nervosa (AN) patients and 5 normal subjects. The patients were young (12-18 years) females (except for 1 case) and had less than 10% of their body weight as fat. The basic experiments were conducted in a moderate environment (24°C)at approximately 65 % maximal aerobic power output on all patients and controls. In addition, 2 patients were studied in warm (32°C) conditions, 1 patient in cool (12°C) conditions and 2 patients after being heated for 30 min in a sauna at a temperature of approximately 50°C. Measurements included oxygen uptake, metabolic (M) and total heat production, evaporative sweat loss (E), rectal (Tre)and mean skin temperatures. The results showed that T,, (for a given M) was higher and E lower in the patients than the controls. Passively heating the anorexia patients hefore exercise increased resting T,, and E but did not affect the “plateau” value of TrFobtained at the end of work. In the warm environment, T,, rose to the same level as observed at 24°C but did not rise atmve the resting value in cool conditions. Thus it ,would appear that although patients with AN can regulate their body temperature adequately in a moderate environment, loss of body fat which reduces thermal insulation may decrease the range of ambient temperatures over which T,, can be maintained during exercise. Our data do not‘ support the theory of a loss of central (hypothalamic) thermoregulatory control in anorexia.
show signs of vitamin, iron or protein deficiency diseases. One of the major physical concerns of the patients is a feeling of cold, particularly in the extremities. Their hands and feet even in a thermally neutral environment are vasoconstricted, acrocyanosed and give rise to a feeling of numbness and sometimes pain. It is surprising therefore that although low body temperatures and hypothermia (22) have often been reported in AN, few attempts have been made to study thermoregulation in this disease. Wakeling and Russel (21) have reported the effects of a localized peripheral heat stress, induced by placing the arm up to the elbow in water at 4S”C, on oral and finger temperatures in 11 anorexic girls. Gleeson and Moore (10) have studied the effects of mild heat and Mecklenburg et al. (14) of cold stress in a climatic chamber on 5 anorexia nervosa patients. To our knowledge, no attempt has been made to study the thermoregulatory responses t o a given metabolic heat load resulting from exercise in AN. The present investigation examines metabolic and thermal responses to prolonged work in 10 patients with AN and 5 healthy normal subjects. SUBJECTS A N D METHODS The patients formed part of a larger study ( 8 , 9). They conformed to the following criteria for AN, chiefly accord-
Key words: anorexia nervosa. temperature regulation,
prolonged exercise, rectal temperature, skin temperature, sweat loss. Acta Med Scand 205: 2.57. 1979.
’ On leave of absence from the Medical Research Council, Environmental Physiology Unit, London School of Hygiene & Tropical Medicine. London. England.
Primary anorexia nervosa (AN) is universally characterized by weight loss due to a failure to eat (3, 5). The physical features of AN are those of chronic inanition; the patients are often extremely emaciated with pallid and sallow skin but rarely
Abbreviations: AN=anorexia nervosa, Vo,=oxygen uptake, V,,2 max = maximal aerobic power, rlP= rectal temperature, T,k = skin temperature, = mean temperature, M = metabolic heat production, H = total heat production, E = evaporative sweat loss, S = heat storage, T,,,,= dry temperature, T,,, = wet temperature, C = convection. R = radiation.
17 7929x4
258
C. T. M . Duvies et al.
Table I . Physicul c/~crrrrc~tr~istic~,s of' the p t i e n t s cind controls (mean f I S.D.) Ht=height, Wt=weight, LBM=lean body mass Ht (cm)
(v.) Patients (n=IO) Controls
15.0 f2.0 14.9 t3.1
(n=5)
164
Wt
LBM
Vc,,max
(kg)
(kg)
(I/iin)
34.1 f7.2
1.18 t0.30 2.30 k0.47
I
37.9
&I5
t8.1
166 +I4
48.9 212.9
I
ing to Dally ( 5 ) : I ) Age at onset less than 25 years. 2) Active refusal to eat with accompanying pronounced weight loss. 3 ) No evidence of schizophrenia, severe depression or organic diseases. The physical characteristics of the patients with A N and the healthy controls are given in Table I. The anorexic state of the patients had lasted on average for 1.0 year (range 0.5-3 ) prior to the investigation. The normal menstruation and ovulatory cycles had ceased in the female patients at the time of measurement. They were studied at rest and during work on an electrically braked bicycle ergometer at approximately 65 % of their maximal aerobic power (Vo2max) for I hour. The subjects were weighed nude before and immediately after exercise, on a balance accurate to t 10 g. Rectal temperature ( T J was measured during exercise from a thermocouple inserted into the rectum 8 cm above the internal sphincter. Skin temperature (T&) was measured at 14 sites, finger and thumb,
hand, upper and lower arm, forehead, pectoral, sternum, abdomen, scapular, lumbar, anterior and posterior thigh and anterior and posterior calf, at rest and during the 2nd, Xth, 2Oth, 30th, 40th, 50th and 60th min of exercise using a thermistor probe mounted on an applicator. The recordings (except finger and thumb measurement) were weighted after the method of Hardy and Dubois (11). and the average was taken as the mean body skin temperature (Tqk). Oxygen uptake (vjoz) was measured at rest and during the 28-30th and 5840th min of exercise by the open circuit (Douglas bag) technique, Opand COPcontent of expired air being determined by the micro-Schokander technique. Heart rate was calculated from standard ECG recordings at rest and every 2 min during exercise. From the raw data, calculations of metabolic ( M ) and total heat ( H ) production, evaporative sweat loss ( E ) and heat storage (S)were made using standard equations (15). Dry (Tdh)and wet (TwJ temperatures in the laboratory were 23.6k0.84 and 14.lf2.2"C, respectively. In two patients the experiments were repeated with and without preheating. For this purpose the patients sat in a sauna for 30 min at about 50°C T,lband 26°C T,,, prior to exercise. In addition, two patients performed exercise at an elevated environmental temperature (Tdb 32.2k0.4, Twb=1 7 . 6 t 1.40"C) and one patient worked in a cool environment (T,,,, 11.7k0.4, Twb6.4kO.S"C). Control experiments were conducted on 4 healthy boys and one healthy girl (Table I) in the laboratory and 2 healthy boys in the cool and warm environments. V o , max was measured in the patients and control subjects on separate occasions. For reasons previously given and discussed (8) it was impossible to establish with abso-
Table 11. Thermoregulatory responses to exercise oj ' A N patients and controls (mean fS.D.)
12°C Patients (n=I)
1.31
73
90
447
357
36.58
30.09
36.80
29.10
3
Controls (n=?)
1.88
58
I40
64 I
508
37.10
30.98
38.40
28.94
153
270 215 i6h +so 548*** 432 +I32 +I00
36.60 t0.56
3 1.68 t0.73
38.07 k0.51
32.18 k1.15
54 t35
37.22**
to.19
32.11 k0.64
38.36 k0.36
31.30 k0.61
k69
24°C Pati en t s (n=IO) Controls (n=5)
0.78 66 t0.20 +I0 1.61*** 64 f0.39 fX
54
i I7 Il6*** t32
267***
24°C with preheating Patients (n=2) 32°C Patients (n=2)
1.07
68
80
363
298
36.75
33.43
38.40
32.60
1 12
0.91
56
75
311
236
36.55
33.19
38.25
35.84
136
Controls (n=2)
1.78
62
123
607
484
37.70
33.75
38.40
33.46
415
***p
