Scientists have found that while female and male muscles handle glucose and fatty acid differently, regular exercise quickly brings on positive metabolic changes in the muscles of both sexes.
The findings could help health experts develop tailored exercises in the drive to prevent obesity and type 2 diabetes, the researchers say.
Exercise has a significant impact on skeletal muscle, with first author Dr Simon Dreher explaining: “Exercise preserves insulin sensitivity in healthy individuals and restores it in those with prediabetes or type 2 diabetes.
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“However, there are sex-related differences in how skeletal muscle uses glucose and lipids.
“A greater understanding of how the underlying molecular differences between the skeletal muscles of females and males affect their response to exercise could provide valuable insight into how to tailor exercise recommendations to more effectively prevent or delay the progression of type 2 diabetes. It could also help with the prevention of obesity.”
Dr Dreher, from the Institute for Diabetes Research and Metabolic Diseases in Germany, and his colleagues examined the molecular differences in muscle biopsies from nine men and 16 women.
The group was made up of healthy individuals aged, on average, 30 with obesity or overweight. None of the participants engaged in regular exercise.
They undertook an hour of exercise three times a week for eight weeks. Biopsies were collected while participants were in a resting state, then after the first exercise session and then again after the last session of exercise at eight weeks.
The muscle cells and fibres from the biopsies were examined using epigenomics (looking at the chemical changes that influence whether genes are switched on or off), transcriptomics (the study of RNA molecules) and proteomics (looking at the structure and function of proteins).
Differences between male and females were found in levels of the RNA strands in skeletal muscle associated with glucose homeostasis (the control of blood sugar levels) and also in insulin signalling, which is how insulin gets sugar out of the blood and into cells.
The scientists also found variances in the proteins male and female muscles used to convert food into energy.
Dr Dreher said: “This, in line with the RNA results, suggest that the male muscle has a higher capacity to exercise on glucose while females use more fatty acids.
This difference in substrate use might be of relevance during exercise and also influence the development of type 2 diabetes.”
In terms of the impact of exercise on muscles, the team found that the males’ muscles showed much more evidence of cellular stress, which could mean that their muscles find it harder to adapt to exercise compared to females.
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However, after the eight weeks, these differences became less apparent and, in both males and females, protein levels involved in converting food into energy had gone up.
Study lead Professor Cora Weigert explained: “This is important because the increased capacity after exercise to use glucose and lipids for energy production is generally regarded as key to prevent type 2 diabetes.
“While initial response of skeletal muscles to exercise differs between females and males, repeated exercise appears to cancel out these differences and trigger beneficial metabolic changes in both sexes.”
The findings are being presented at the Annual Meeting of the European Association for the Study of Diabetes in Madrid in September.
