Mitochondrial abnormalities and their contribution to or causation of NIDDM is a hot topic in metabolism. It has been demonstrated that mitochondrial efficiency is decreased in diabetics, although this has recently been challenged. Importantly, these studies were done in obese NIDDM subjects. However, it has been demonstrated that this mitochondrial deficiency can be restored to normal levels with exercise training, indicating that energy production should not be impaired in those with diabetes undergoing regular exercise training. An important point of consideration is that the majority of studies performed in those with well-controlled diabetes are in those with controlled diabetes. Certainly the diabetic athlete has to take preventive measures to ensure controlled glucose concentrations during exercise training, something that regular exercise training may actually improve.Sex Differences
For many years, all of the examples used in the field of exercise metabolism were based on observations from the standard 70-kg male. With increased participation of women in sport through Title IX and The Women’s Health Equity Act of the 1990s, physiologists and biochemists began to investigate sex-based differences in women and men. Presumably because the experiments were initially done on men, femaleness (and the physiological effects of the ovarian hormones estrogen and progesterone) is still treated as the “experimental” condition and males the “control.” Most well-controlled studies show that at any given relative exercise intensity, men oxidize more carbohydrate and less fat than do women. It appears that the differences between the patterns of relative fuel use in men and women are due to circulating female hormones rather than male hormones or the relatively greater proportion of type I fibers in women than men.
