Sitting comfortably versus lying down: Is there really a difference in energy expenditure?

Abstract

Background & aims: Energy expenditure (EE) during sitting is widely assumed to be higher than that while lying down, but supporting evidence is equivocal. Despite this, resting EE in the sitting position is often used as a proxy for basal metabolic rate. Here we investigate whether EE differs in the comfortable seated position compared to supine (lying) position. Methods: EE and respiratory quotient (RQ) were measured (by ventilated hood indirect calorimetry) in 19 healthy subjects (9 men, 10 women) after an overnight fast. Supine measurements were made using a comfortable clinical tilting table and sitting measurements made using an adjustable, ergonomic car seat adapted for the hood system. After about 30 min of rest in either position, metabolic monitoring was conducted until stabilization of EE for at least 15 min in each posture. Results: EE in the sitting position was not significantly different compared to supine (<2% difference). By contrast, heart rate was higher by 7 beats/min (p < 0.05). RQ was slightly but significantly decreased during sitting compared to lying (p < 0.05), with no change in breathing rate. Conclusions: This study suggests that the ventilated hood calorimetry system for assessment of REE after an overnight fast in a comfortable sitting position can be used as a good proxy of the basal metabolic rate. It also underscores the applicability of the ventilated hood system to measurements of resting EE in the sitting posture which, compared to supine posture, may be more acceptable/convenient to the subject/ patient participating in postprandial metabolic studies lasting several hours.

Posture Allocation Revisited: Breaking the Sedentary Threshold of Energy Expenditure for Obesity Management

“…However, this alone may not be sufficient to noticeably increase EE. Indeed, in addition to demonstrating that the majority of individuals (>75%) are able to maintain a standing posture at a similar level of EE to sitting (Miles-Chan et al, 2013, 2017), we have also shown that sitting in a comfortable chair, with the body weight well-supported, does not significantly increase EE above supine levels (<2% difference; Miles-Chan et al, 2014). In fact, based on these findings, replacing 2.5 h per day of lying or sitting by standing is in itself unlikely to increase daily EE by any more than 20 kcal (i.e., <1%); this is considerably less than the amount postulated by others (Levine et al, 2005; Johannsen et al, 2008).…”

“…This increased heart rate persists across the standing period, and can occur in the absence of any obvious change in EE; as consistently observed in our recent studies where all individuals showed comparable increases in heart rate during steady-state standing (~15 beats per minute), despite responses in terms of EE ranging from little or no change compared to sitting to an increase of ~25% (Miles-Chan et al, 2013, 2017). Similarly, despite no detectable change in EE, we have also shown a significant difference in heart rate during sitting compared to supine ~7 beat per minute (Miles-Chan et al, 2014). Further, dissociation between the heart rate and EE response to altered body posture can be demonstrated in our preliminary study in healthy young men, performed using a clinical tilting table.…”

Effects of Posture and Stimulus Spectral Composition on Peripheral Physiological Responses to Loud Sounds

“…There is ample evidence for higher resting HR in the sitting, compared to supine, position [17–19], which is in line with our results. However, in contrast to the different HR levels, we observed comparable HR response magnitudes to the stimuli when subjects were tested in the sitting and supine positions.…”

“…Previous research has suggested that resting HR level is higher in the sitting than supine position [17–19]. However, it is not clear whether HR responses to stimuli such as loud sounds are influenced by posture.…”

“…We hypothesized that white noise stimuli would induce larger autonomic and eye blink responses than pure tones [11]. Given previous findings of higher resting HR level in the sitting position [17–19], we expected to observe larger HR responses to the auditory stimuli in the sitting, compared to supine, position.…”