Continuous endurance‐type exercise training does not modulate satellite cell content in obese type 2 diabetes patients

Abstract

Endurance-type exercise training represents a cornerstone in type 2 diabetes treatment. However, the effects of prolonged continuous, endurance-type exercise on muscle fiber characteristics remain equivocal. Fifteen obese male type 2 diabetes patients (61 6 6 years) participated in a 6-month continuous, endurance-type exercise program. Muscle biopsies were collected before, and after 2 and 6 months of intervention. Muscle fiber type-specific composition, size, and satellite cell (SC) and myonuclear content were determined by immunohistochemistry. Although continuous endurance-type exercise training lowered total body weight and reduced fat mass, no changes were observed in leg lean mass. At baseline, SC content was significantly lower in type II compared with type I muscle fibers. No change in SC content was observed after exercise training. Continuous endurance-type exercise training lowers fat mass, but it does not increase leg lean mass and/or modulate muscle fiber characteristics in type 2 diabetes patients.

Evidence for the contribution of muscle stem cells to nonhypertrophic skeletal muscle remodeling in humans

“…Given the induction of muscle hypertrophy using the training protocols with high‐intensity bouts of exercise, it is plausible that high‐intensity type activity for prolonged periods of time may induce hypertrophy and hence SC activity. In addition, each study reporting on the expansion of the SC pool following endurance type training in humans reported no change in fiber type distribution (20–22). This further highlights the fact that the expansion of the SC pool associated with training likely resulted from muscle hypertrophy and was not due to a fiber‐type transition induced by training.…”

“…Both studies reporting an increase in SC content following training had training protocols consistent with interval‐type training in which subjects completed 4 min of low‐intensity cycling followed by 1 min of high‐intensity cycling for a total of 40–45 min 3–4 d/wk for 14 wk (20, 21). The study that reported no change in SC content had a more modest endurance training protocol, in which subjects completed 40 min of low‐intensity exercise 3 d/wk for 6 mo (22). Given the induction of muscle hypertrophy using the training protocols with high‐intensity bouts of exercise, it is plausible that high‐intensity type activity for prolonged periods of time may induce hypertrophy and hence SC activity.…”

“…20, 21], while others report no change using a more traditional endurance training protocol (40 min of exercise at 75% V o 2 peak; ref. 22). Both studies reporting an increase in the number of SCs also showed an increase in type IIa fiber cross‐sectional area (CSA) with intermittent cycle ergometer training (20, 21).…”

The effects of high-fat diet, branched-chain amino acids and exercise on female C57BL/6 mouse Achilles tendon biomechanical properties

“…10 Other studies showed no difference with resistance training in older women 11 or continuous endurance-type exercise in obese patients with type 2 diabetes. 12 Many athletic trainers and others advocate the use of branched-chain amino acid (BCAA) supplementation during exercise training. BCAA supplementation decreases muscle damage associated with resistance training.…”

Roles played by protein metabolism and myogenic progenitor cells in exercise-induced muscle hypertrophy and their relation to resistance training regimens

“…After a 14-wk training period, the numbers of NCAM-positive satellite cells increased in both upper and lower limb muscles, whereas the numbers of myonuclei were unchanged 102) . Recently, Snijders et al reported that a 6-month endurance-type exercise did not alter the number of satellite cells in muscles of type 2 diabetes patients 103) . Although further studies are needed, endurance exercise appears to stimulate, to some extent, the proliferation of satellite cells in healthy subjects.…”