SUMMARY1. The ventilatory response to electrically induced exercise was studied in thirteen patients with traumatic spinal cord transaction at or about the level of T6. The steady-state and on-transient responses to this exercise were compared with those obtained in eighteen normal subjects (Adams, Garlick, Guz, Murphy & Semple, 1984).2. Exercise was produced by surface electrode stimulation of the quadriceps and hamstring muscles so as to produce a pushing movement at 1 Hz against a spring load.3. At rest there was no significant difference between normals and patients, except that the patients had a lower CO2 elimination (Pco2) and end-tidal Pco, (PET,Co2) and a higher heart rate. 5. In the steady state there was a mean rise in PETCO, of 0-9 mmHg (S.D. 1-4) in the normals, and 3-2 mmHg (S.D. 2 7) in the patients, but there was overlap between the two groups. In many experimental runs in both groups, PET,Co2 did not rise, and sometimes fell. Where PCO2 did rise, the ventilatory response to exercise could not be accounted for on the basis of the ventilatory sensitivity to CO2 inhalation. From arterial sampling in three of the patients it was found that when PETC02 rose, the corresponding change in Paco2 was less.6

SUMMARY1. The ventilatory response to electrically induced exercise (EEL) was studied in eighteen normal subjects and compared with the response to performing the same exercise voluntarily (EV).2. EEL was produced by surface electrode stimulation of the quadriceps and hamstring muscles so as to cause a pushing movement at 1 Hz against a spring load; this produced no pain or discomfort. Matching of Ev to EEL was achieved by subjects copying a tension signal recorded during EEL and displayed on a storage oscilloscope.3. There were no differences between the resting states measured before either form of exercise.4. The ventilatory response (change in ventilation as a ratio of the change in CO2 elimination) was similar in the two types of exercise. The increases in ventilation and CO2 elimination were greater with EEL. Small but significant increases in the gas exchange ratio and serum lactate were found for EEL but not for Ev, suggesting an increase in anaerobic metabolism in EEL. End-tidal PcO, showed little change in either form of exercise. In some runs end-tidal PCO2 rose, but insufficiently to account for the ventilatory response as judged by the response to inhaled CO2.5. In two subjects arterial blood samples showed small and inconsistent changes in both Paco, and Pao2 for Ev and EEL. pH and base excess changes also were consistent with more anaerobiosis with EEL compared to Ev.

IntroductionDuring social interactions, our own physiological responses influence those of others. Synchronization of physiological (and behavioural) responses can facilitate emotional understanding and group coherence through inter-subjectivity. Here we investigate if observing cues indicating a change in another's body temperature results in a corresponding temperature change in the observer.MethodsThirty-six healthy participants (age; 22.9±3.1 yrs) each observed, then rated, eight purpose-made videos (3 min duration) that depicted actors with either their right or left hand in visibly warm (warm videos) or cold water (cold videos). Four control videos with the actors' hand in front of the water were also shown. Temperature of participant observers' right and left hands was concurrently measured using a thermistor within a Wheatstone bridge with a theoretical temperature sensitivity of <0.0001°C. Temperature data were analysed in a repeated measures ANOVA (temperature × actor's hand × observer's hand).ResultsParticipants rated the videos showing hands immersed in cold water as being significantly cooler than hands immersed in warm water, F(1,34) = 256.67, p<0.001. Participants' own hands also showed a significant temperature-dependent effect: hands were significantly colder when observing cold vs. warm videos F(1,34) = 13.83, p = 0.001 with post-hoc t-test demonstrating a significant reduction in participants' own left (t(35) = −3.54, p = 0.001) and right (t(35) = −2.33, p = 0.026) hand temperature during observation of cold videos but no change to warm videos (p>0.1). There was however no evidence of left-right mirroring of these temperature effects p>0.1). Sensitivity to temperature contagion was also predicted by inter-individual differences in self-report empathy.ConclusionsWe illustrate physiological contagion of temperature in healthy individuals, suggesting that empathetic understanding for primary low-level physiological challenges (as well as more complex emotions) are grounded in somatic simulation.

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