Effects of stairclimbing on VO2max and quadriceps strength in middle-aged females.

The purpose of this study was to determine the effect of 12 wk of stairclimbing with and without an external load on aerobic capacity and quadriceps strength of sedentary (initial VO2max 25.3 +/- 0.73 ml.kg-1.min-1) (mean +/- SEM) middle aged females (50-65 yr). Three groups, LOAD (stairclimbing with external load, N = 8), STAIR (no load, N = 9), and CONTROL (N = 7) were tested. By week 4, subjects warmed up 5 min on a cycle ergometer followed by 35 min on the stairclimber at 80-85% maximum heart rate (MHR) 4 d.wk-1. In week 6, the LOAD group carried an external load of 4% of body weight increasing to 8% for weeks 7-12. STAIR and LOAD group significantly increased (P < 0.01) VO2max by 11.1% and 9.6%, respectively. Isokinetic strength tests showed increased (P < 0.05) peak torque and total work for STAIR and LOAD at 120 and 180 degrees.s-1. For total work, a significant increase (P < 0.05) of 10.5% was observed at 60 degrees.s-1 for the LOAD group. The results indicate stairclimbing is an appropriate exercise for middle-aged females improving both aerobic capacity and strength following 12 wk of training.

Does essential fatty acid absorption change with aging?

Linoleic acid, an essential fatty acid, is a prostaglandin precursor. We investigated the maximal capacity of the proximal jejunum and distal ileum to absorb linoleic acid in the unanesthetized rat. Groups of rats 1, 3, 12, and 28 months of age were studied. As the rats aged, their maximal capacity to absorb linoleic acid increased fivefold both in the jejunum and ileum. Since the intestinal wall content of linoleic acid remained relatively constant, age-related changes in mucosal surface area could not account for our observations. A decrease in the unstirred water layer thickness with aging was detected by measuring potential difference changes across the bowel. The total surface area of the unstirred water layer increased some fourfold and its resistance to linoleic acid transfer decreased fivefold with aging. These changes in the dimensions and characteristics of the unstirred water layer with aging may account for the fivefold increase in the maximal capacity of the small bowel to absorb linoleic acid.

Does the non-absorbable fat, (sucrose polyester), interfere with the intestinal absorption of vitamin A?

Sucrose polyester (SPE) is a synthetic non-absorbable lipid. The effect of SPE on vitamin A absorption was determined by monitoring the disappearance rate of radio-labeled vitamin A from the jejunal perfusate of the rat. The relative distribution of radio-labeled vitamin A between the micellar phase and the perfusate containing SPE was determined. With SPE concentrations of 5, 10 and 20 g/l, vitamin A was concentrated in the SPE phase over the micellar phase by a factor of 4.4, 9.4, 19.8 respectively. Thus, vitamin A favored the SPE phase over the micellar phase in the distribution analysis. In vivo absorption experiments with SPE and non-SPE perfusates showed decreased net vitamin A absorption rates in the presence of SPE by 8.7% Thus, dietary ingestion of SPE results in some impairment of intestinal absorption of vitamin A, and may require vitamin A supplementation.