News & Views from the Editor-in-Chief - L. Bruce Gladden
I have a very interesting group of papers to highlight in this month's journal. First, Keller et al. reported that menstrual blood loss had no impact on hemoglobin mass, a marker of oxygen-carrying capacity, over the course of one menstrual cycle in eumenorrheic women. Interestingly, hemoglobin mass was 12% greater in women using oral contraceptives in comparison to women not using oral contraceptives, possibly due to a reduced menstrual blood loss and an adequate iron availability in women using oral contraceptives. Because hemoglobin mass strongly predicts maximal oxygen uptake, the greater oxygen-carrying capacity associated with the use of oral contraceptives could lead to a greater maximal oxygen uptake. This begs further study since a limited number of studies have reported either no change or a decrease in maximal oxygen uptake with the use of oral contraceptives.
Second, Cešeiko and colleagues investigated the effects of leg press maximal strength training (MST) in patients with early-stage breast cancer undergoing adjuvant chemotherapy. Twenty-four sessions of MST, performed with high intensity (~90% of one repetition maximum), increased maximal muscle strength by approximately 20%. There was also a tendency for leg muscle mass to increase in the MST group. Conversely, patients receiving only conventional therapy displayed reductions in all variables. The changes in strength were strongly associated with changes in functionality (e.g., increased time to exhaustion during incremental walking, increased 6-min walking distance, and stair climbing performance). These results imply that not only may patients maintain strength and functionality during adjuvant chemotherapy, they may even exhibit significant gains in these critical components. These are important findings which encourage the use of MST as a strategy to counteract chemotherapy-induced reductions in physical function.
Third and last, Barber coworkers examined rates of digestion, absorption, and oxidation of ingested carbohydrates during running when carbohydrates were ingested as single-source (glucose-based), or dual-source (fructose-glucose mixtures) in the absence or presence of pectin and sodium alginate (creating a carbohydrate hydrogel). They found that combining fructose with glucose-based carbohydrates increased oxidation rates of the ingested carbohydrate during running when compared with equivalent ingestion of glucose-based carbohydrates alone. However, the addition of pectin and sodium alginate provided no further increase in exogenous carbohydrate oxidation. These findings suggest that runners wishing to maximize carbohydrate availability during training or racing should consider ingesting fructose–glucose mixtures, but encapsulating carbohydrate mixtures within a hydrogel is unlikely to further increase carbohydrate availability during moderate-intensity running.
L. Bruce Gladden
School of Kinesiology