Original research
Intermittent walking, but not standing, improves postprandial insulin and glucose relative to sustained sitting: A randomised cross-over study in inactive middle-aged men

https://doi.org/10.1016/j.jsams.2016.08.012Get rights and content

Abstract

Objectives

Interrupting prolonged periods of sitting may improve postprandial insulin and glucose although it is unclear whether interruptions need to involve physical activity or simply a change in posture (from sitting to standing) to benefit adults without metabolic impairment. This study examined effects of interrupting sitting with intermittent walking, and intermittent standing on dynamic insulin and glucose responses in men without known metabolic impairment.

Design

A randomised three-arm, cross-over experimental study comprising three seven-hour days of sustained sitting.

Methods

Twenty-five inactive men (aged 40.2 ± 12.2 years) took part. The three interventions were; SIT-ONLY (uninterrupted sitting), SIT-STAND (sitting interrupted with 2 min standing bouts every 20 min) and SIT-WALK (sitting interrupted with 2 min light-intensity walking bouts every 20 min). An oral glucose tolerance test was administered at baseline and a standardised mixed test meal at hour three. Comparisons of Matsuda Index, and area under the curve (AUC) for insulin and glucose were made between interventions using generalised estimating equation models.

Results

Matsuda index was 16% higher (mean difference 1.2 [95%CI 0.1, 2.2] p = 0.02), AUC for glucose 9% lower (−2.5 mmol/L × 7 h [−3.7, −1.3 mmol/L × 7 h] p < 0.001) and AUC for insulin 21% lower (−546.5 pmol/L × 7 h [−723.6, −369.3 pmol/L × 7 h] p < 0.001) in SIT-WALK compared to SIT-ONLY. There were no significant differences between SIT-STAND and SIT-ONLY in any main outcome measure.

Conclusions

Interrupting sustained sitting with brief repeated bouts of light-intensity walking but not standing reduced insulin demand and improved glucose uptake during a simulated sedentary working day. The benefits of such minor behavioural changes could inform future workplace health interventions.

Introduction

Poor glycaemic control is an important contributor to global morbidity and mortality,1 both directly through microvascular complications and through the associated 2–3 fold increase in cardiovascular disease risk.2 Physical activity provides a valuable tool in reducing diabetes and cardiovascular risk but advancements in technology and the social and built environments, have reduced necessity for physical activity, and increased our propensity for sitting.3 Adults spend up to 10 h per day sitting,4 including over 75% of working hours,5 as the proportion of people in largely sedentary occupations increases.6 Observational studies report positive associations between daily sitting time and risk for diabetes,7 and insulin resistance8 that are independent of moderate to vigorous intensity physical activity (MVPA) participation.

Interrupting sustained periods of sitting with regular bouts of walking of at least light intensity9, 10, 11 can reduce circulating glucose and insulin. However, it is unclear whether these beneficial effects are due to interrupting sitting per se (a change in posture) or the increase in muscle contraction resulting from walking, a difference which is important for any future workplace health promotion. To address this question it is necessary to examine the effects of interrupting sitting with standing (a posture change only), and with a change in physical activity (through walking). Evidence regarding the effectiveness of intermittent standing is lacking. A recent study observed that short standing breaks improved postprandial insulin and glucose in overweight and obese postmenopausal women with impaired glucose regulation,12 but it is unclear whether such effects would also be observed in men without known metabolic impairment by at least reducing insulin demand, in the control of glucose homeostasis, which has so far not been addressed.11 This would establish the value of standing breaks in the prevention of metabolic disease, rather than treatment. This study aimed to address these questions by examining the dynamic responses of both insulin and glucose in men without metabolic impairment, during sustained sitting and when sitting is interrupted by (1) intermittent standing and (2) intermittent walking. Specifically the present study tested the hypothesis that intermittent standing and walking would improve glucose and insulin responses relative to sustained sitting.

Section snippets

Methods

A three-intervention experimental study with a cross-over design was approved by the University of Exeter departmental ethics committee (approval number 2013/410). Written informed consent was obtained from all participants prior to their involvement.

Participants were recruited from a research volunteer database, the ‘Exeter Ten-thousand’ (Extend – http://www.exeter.crf.nihr.ac.uk/node/155) held by the NIHR Clinical Research Facility in Exeter, and from advertisements sent to University

Results

Twenty-five men completed the study and baseline characteristics are detailed in Table 1. Steady state EE (mean ± SD, range) for walking at 2 mph (2.7 ± 0.4METs, range 2.0–3.4) measured at the preliminary visit was significantly higher than for standing (1.1 ± 0.2METs, range 0.9–1.5, p < 0.001) and sitting (1.0 ± 0.2METs range 0.7–1.3, p < 0.001). Values for standing and sitting did not differ (p = 0.1). Minutes of MVPA measured during the 48 h restricted pre-study period were 125.6 ± 58.9 min, SIT-ONLY; 139.7 ± 

Discussion

In a cross-over study of 25 inactive middle-aged men we observed that interrupting a 7 h day of sustained sitting with short bouts of light intensity walking significantly increased Matsuda index, and reduced dynamic insulin and glucose responses, while interrupting sitting with standing bouts of the same duration did not. These findings address important gaps in the existing literature by examining the potential effects of intermittent standing, as well as light intensity walking on insulin and

Conclusions

The present findings suggest that interrupting sustained sitting with brief light intensity walking bouts benefits postprandial insulin and glucose in inactive men without metabolic impairment. Introducing short, frequent bouts of light intensity physical activity into sedentary lifestyles could play an important role in the prevention of metabolic disorders.

Practical implications

  • Being inactive for sustained periods is detrimental to blood sugar regulation.

  • Interrupting sitting with frequent short walking breaks (2 min) can improve regulation of blood sugar.

  • Interrupting sitting by simply standing up for short periods 3 times per hour may not benefit regulation of blood sugar in people without metabolic disease, some additional movement or activity may be required.

Acknowledgements

We would like to acknowledge the study participants, without whom this research would not have been possible. This research was funded internally through a University of Exeter Science Strategy PhD Studentship (Richard Pulsford) in collaboration with the National Institute for Health Research (NIHR) Collaborations for Leadership in Applied Health Research and Care (CLAHRC). The research was supported by the National Institute for Health research (NIHR) Exeter Clinical Research Facility. The

References (30)

  • J.B. Marks et al.

    Cardiovascular risk in diabetes: a brief review

    J Diabetes Complications

    (2000)
  • J.G. van Uffelen et al.

    Occupational sitting and health risks: a systematic review

    Am J Prev Med

    (2010)
  • M.C. Peddie et al.

    Breaking prolonged sitting reduces postprandial glycemia in healthy, normal-weight adults: a randomized crossover trial

    Am J Clin Nutr

    (2013)
  • C.D. Mathers et al.

    Projections of global mortality and burden of disease from 2002 to 2030

    PLoS Med

    (2006)
  • R.C. Brownson et al.

    Declining rates of physical activity in the United States: what are the contributors?

    Annu Rev Public Health

    (2005)
  • L. Smith et al.

    Weekday and weekend patterns of objectively measured sitting, standing, and stepping in a sample of office-based workers: the active buildings study

    BMC Public Health

    (2015)
  • T.J. Parsons et al.

    Estimated activity patterns in British 45 year olds: cross-sectional findings from the 1958 British birth cohort

    Eur J Clin Nutr

    (2009)
  • F.B. Hu et al.

    Television watching and other sedentary behaviors in relation to risk of obesity and type 2 diabetes mellitus in women

    JAMA

    (2003)
  • H.J. Helmerhorst et al.

    Objectively measured sedentary time may predict insulin resistance independent of moderate- and vigorous-intensity physical activity

    Diabetes

    (2009)
  • D.W. Dunstan et al.

    Breaking up prolonged sitting reduces postprandial glucose and insulin responses

    Diabetes Care

    (2012)
  • D.P. Bailey et al.

    Breaking up prolonged sitting with light-intensity walking improves postprandial glycemia, but breaking up sitting with standing does not

    J Sci Med Sport

    (2014)
  • J. Henson et al.

    Breaking up prolonged sitting with standing or walking attenuates the postprandial metabolic response in postmenopausal women: a randomized acute study

    Diabetes Care

    (2016)
  • T.G. Pickering et al.

    Recommendations for blood pressure measurement in humans and experimental animals: Part 1: blood pressure measurement in humans: a statement for professionals from the Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research

    Hypertension

    (2005)
  • G.F. Fletcher et al.

    Exercise standards. A statement for health professionals from the American Heart Association

    Circulation

    (1990)
  • M.M. Reeves et al.

    Reducing the time period of steady state does not affect the accuracy of energy expenditure measurements by indirect calorimetry

    J Appl Physiol (1985)

    (2004)
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