Effect of type 2 diabetes in muscle deoxygenation during ramp incremental exercise in older individuals

A.D. McDermott, Norita Gildea, Aaron Nevin, Joel Rocha, Donal O'Shea, Simon Green, Mikel Egana

Research output: Contribution to conferenceAbstract

Abstract

Peak oxygen uptake (VO2peak) in people with type 2 diabetes (T2D) of all ages is significantly lower than in healthy individuals (Green et al. 2015). In middle-aged individuals with T2D (< 55yrs) there appears to be an over reliance in fractional oxygen extraction during maximal ramp incremental exercise (RI), reflected by an increased rate of muscle deoxygenation (i.e., deoxygenated haemoglobin and myoglobin, [HHb+Mb]) (Gildea et al. 2016).To better understand the reduced VO2peak responses observed in older individuals (>60 yrs) with uncomplicated T2D the present study investigated whether T2D also alters the profile of muscle fractional O2 extraction in older individuals with uncomplicated T2D during incremental cycling exercise. Twelve older participants (9 men, 3 women) with T2D (age: 63.0 ± 2.9 yrs range: 59.8 – 67.4 yrs; BMI: 29.2 ± 4.1 kg.m-2) and twelve older healthy controls (9 men, 3 women) (age: 64.5 ± 3.9 yrs range: 59.3 – 68.2 yrs; BMI: 27.5 ± 2.8 kg.m-2) took part in the study. Each participant completed a ramp incremental cycling test to volitional exhaustion in an upright position followed by a verification test. Exercise was performed on an electrically braked cycle ergometer with participants initially exercising for 2-min at 10W before the intensity increased by 10-15W.min-1 for women and 15-20W.min-1 for men. Pulmonary oxygen uptake (VO2) was measured on a breath-by-breath basis with an online metabolic system while muscle deoxygenation was assessed using near-infrared spectroscopy (NIRS) at the vastus lateralis muscle. Normalised [HHb+Mb] profiles ([HHb+Mb]%) were plotted as a function of relative work rate (%POpeak) using a bilinear model. Physiological variables were compared using unpaired t-tests or Mann-Whitney U tests with statistical significance set at P < 0.05. Values are means ± SD. Normalised VO2peak was significantly (P < 0.05) reduced in the older individuals with T2D compared with the heathy older controls (23.9 ± 4.1 mL.kg.min-1 vs 27.2 ± 5.3 mL.kg-1.min-1), representing a 12% reduction in peak exercise capacity. There was no difference in the slope of the first linear component of the ∆[HHb+Mb]% vs ∆%POpeak profile (S1) between the 2 groups (Controls: 1.82 ± 0.8 a.u vs T2D: 1.81 ± 0.6 a.u.). Such findings are suggestive that in contrast to middle-aged individuals with T2D, a greater rate of oxygen extraction for a given increase in VO2, indicative of reduced O2 delivery, is not a contributing factor to the reduction in VO2peak observed in older individuals with T2D compared to healthy controls.
Gildea N, Rocha J, O’Shea D, Green S & Egaña M (2016). The effect of type 2 diabetes in muscle deoxygenation during ramp incremental exercise. Poster communication, Biomedical Basis of Elite Performance, East Midlands Conference Centre, Nottingham, UK.Green S, Egana M, Baldi C, Lamberts R & Regensteiner J (2015). Cardiovascular control during exercise in type 2 diabetes mellitus. J Diabetes Res 2015, 1-11.
Original languageEnglish
Publication statusPublished - 10 Jul 2019
EventPhysiology 2019 - Aberdeen Exhibition and Conference Centre, Aberdeen, United Kingdom
Duration: 8 Jul 201910 Jul 2019
http://www.physoc.org/physiology2019/physiology-2019

Conference

ConferencePhysiology 2019
CountryUnited Kingdom
CityAberdeen
Period8/07/1910/07/19
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McDermott, A. D., Gildea, N., Nevin, A., Rocha, J., O'Shea, D., Green, S., & Egana, M. (2019). Effect of type 2 diabetes in muscle deoxygenation during ramp incremental exercise in older individuals. Abstract from Physiology 2019, Aberdeen, United Kingdom.