Impact of Ageing on Female Metabolic Flexibility: A Cross-Sectional Pilot Study in over-60 Active Women

Abstract

Background Ageing affects metabolic flexibility, although physical status could influence this relationship. This cross-sectional study aims to describe and analyse the metabolic flexibility/inflexibility in a group of active older women, together with the impact of ageing and physical status on their oxidation rates and maximal fat oxidation (MFO). Methods Fifteen volunteers (69.00 ± 6.97 years)—from 24 women—completed an incremental cycling test until the second ventilatory threshold. Intensity increased 10 W each 3 min 15 s, starting at 30 W. Gas exchange, heart rate, rate of perceived effort, pain scale and muscle power were registered, together with lactate. VO2 and VCO2 were considered for fat and carbohydrate oxidation (FATox and CHOox; Frayn’s equation) at intensities 60%, 80% and 100% from the peak power in the test (P100). Psychophysiological parameters were compared at MFO/FATmax and P100, together with the energy expenditure calculations around MFO (included FAT and CHO contributions), and the main correlation analyses, with and without P100 and VO2 as covariates. Results FATox was low at MFO (0.13; 95% CI [0.09–0.17] mg/min/kgFFM; 3.50; 95% CI [2.49–4.50] mg/min/kgFFM), with short oxidation-rate curves shifting down and leftward. CHOox and FATox were both low for reduced power with age (77.14 ± 18.58 W and 39.29 ± 9.17 W at P100 and MFO, respectively), all accompanied by a fall in energy expenditure (5.44 ± 2.58 kcal/min and 3.32 ± 1.55 kcal/min at P100 and MFO, respectively). Power appears as a determinant factor, given its strong and negative significant association with age (r = − 0.85, p < 0.005; R2 = 0.72) and moderate with MFO (r = − 0.54, p = 0.04; R2 = 0.29). In turn, energy expenditure shows a positive and moderate association with muscle power (r = 52, p = 0.04). Conclusions Despite the drop in substrates oxidation with age, physical status (i.e. larger muscular power and energy expenditure) suggests a key role in the preservation of metabolic health with ageing in active women.

Metabolic flexibility and resting autonomic function in active menopausal women

“…These latter studies underscore the signi cant importance of the autonomic resources at rest for subsequent physical performance, at least at submaximal intensities. In our sample, with maintained metabolic exibility despite the lower energy expenditure (Blasco-Lafarga et al, 2022), this higher physical performance associated with autonomic resources is observed as higher peak fat oxidation at FATmax, together with higher lactate production at submaximal intensities, which in turn is associated with greater total power(Monferrer-Marín et al, 2022). This connection between metabolic exibility and autonomic health reinforces the autonomic resources hypothesis of Hynynen et al(Hynynen et al, 2008).…”

“…Similarly, major interest has been focused on metabolic exibility, or rather its dysfunction, the metabolic in exibility (Frandsen et al, 2021), the latter being an impaired ability to switch energy substrates in response to physiological demands (Galgani et al, 2008). This dysfunction (in exibility) is accompanied by a downward and leftward shift of the energy substrate oxidation curves, resulting in lower fat oxidation at FATmax, and an increase in the rate of carbohydrate oxidation (Monferrer-Marín et al, 2022). Metabolic exibility (or in exibility) is linked to mitochondrial function, but it has an impact beyond the metabolic effect, as it directly associates with cardiovascular health (Wang et al, 2023).…”

Assessment of Physical Fitness in Geriatric Individuals in Loni: A Descriptive Study

“…As age increases, body flexibility tends to decrease. Several studies have shown that aging is associated with a reduction in joint range of motion and flexibility (23).…”