Exercise training results in depot-specific adaptations to adipose tissue mitochondrial function

Abstract

We assessed differences in mitochondrial function in gluteal (gSAT) and abdominal subcutaneous adipose tissue (aSAT) at baseline and in response to 12-weeks of exercise training; and examined depot-specific associations with body fat distribution and insulin sensitivity (S i). Obese, black South African women (n = 45) were randomized into exercise (n = 23) or control (n = 22) groups. Exercise group completed 12-weeks of aerobic and resistance training (n = 20), while the control group (n = 15) continued usual behaviours. Mitochondrial function (high-resolution respirometry and fluorometry) in gSAT and aSAT, S i (frequently sampled intravenous glucose tolerance test), body composition (dualenergy X-ray absorptiometry), and ectopic fat (MRI) were assessed pre-and post-intervention. At baseline, gSAT had higher mitochondrial respiratory capacity and hydrogen peroxide (H 2 o 2) production than aSAT (p < 0.05). Higher gSAT respiration was associated with higher gynoid fat (p < 0.05). Higher gSAt H 2 o 2 production and lower aSAT mitochondrial respiration were independently associated with lower S i (p < 0.05). In response to training, S i improved and gynoid fat decreased (p < 0.05), while H 2 o 2 production reduced in both depots, and mtDNA decreased in gSAT (p < 0.05). Mitochondrial respiration increased in aSAT and correlated with a decrease in body fat and an increase in soleus and hepatic fat content (p < 0.05). This study highlights the importance of understanding the differences in mitochondrial function in multiple SAT depots when investigating the pathophysiology of insulin resistance and associated risk factors such as body fat distribution and ectopic lipid deposition. Furthermore, we highlight the benefits of exercise training in stimulating positive adaptations in mitochondrial function in gluteal and abdominal SAT depots.

Absent Exercise-Induced Improvements in Fat Oxidation in Women With Polycystic Ovary Syndrome After High-Intensity Interval Training

“…However, there are some indications in the literature for exercise-induced changes in adipose tissue mitochondrial respiration. Dohlmann et al (2018) found decreased mitochondrial respiration in subcutaneous abdominal adipose tissue in healthy men and women after 6 weeks of LV-HIT (18 HIT sessions with 7 × 1 min exercise bouts at ∼100% of VO 2 peak), while Mendham et al (2020) reported increased mitochondrial respiration in subcutaneous abdominal adipose tissue in black South-African women with obesity after 12 weeks of combined aerobic and resistance exercise training (4 days/week of 40-60 min with aerobic exercise at 75-80% HR peak and resistance training that included upper-and lower-body exercises at 60-70% HR peak ). We are not sure of the reasons for these divergent findings, but they may be explained by different exercise modalities and intensities.…”

Contribution of Adipose Tissue Oxidative Stress to Obesity-Associated Diabetes Risk and Ethnic Differences: Focus on Women of African Ancestry

“…During excess food consumption, hyperglycaemia and elevated FFAs, the mitochondrial energetic efficiency and ROS production increase [26]. We recently showed that higher gSAT mitochondrial respiratory capacity was associated with higher gluteal fat accumulation in a cohort of African women [167]. Similarly, the resulting higher production of hydrogen peroxide correlated with lower insulin sensitivity in these women [167].…”

Exercise training improves mitochondrial respiration and is associated with an altered intramuscular phospholipid signature in women with obesity

“…Of the 48 exercise sessions, participants attended 79 ± 13% (range 52-100%) at a mean intensity of 79.7 ± 4.0% (range 71-85%) HR peak [42]. There was no change in total habitual physical activity or sedentary time in response to the intervention (Table 1).…”