The Energy Expenditure of Stair Climbing One Step and Two Steps at a Time: Estimations from Measures of Heart Rate

Stairway climbing provides a ubiquitous and inconspicuous method of burning calories. While typically two strategies are employed for climbing stairs, climbing one stair step per stride or two steps per stride, research to date has not clarified if there are any differences in energy expenditure between them. Fourteen participants took part in two stair climbing trials whereby measures of heart rate were used to estimate energy expenditure during stairway ascent at speeds chosen by the participants. The relationship between rate of oxygen consumption () and heart rate was calibrated for each participant using an inclined treadmill. The trials involved climbing up and down a 14.05 m high stairway, either ascending one step per stride or ascending two stair steps per stride. Single-step climbing used 8.5±0.1 kcal min⁻¹, whereas double step climbing used 9.2±0.1 kcal min⁻¹. These estimations are similar to equivalent measures in all previous studies, which have all directly measured The present study findings indicate that (1) treadmill-calibrated heart rate recordings can be used as a valid alternative to respirometry to ascertain rate of energy expenditure during stair climbing; (2) two step climbing invokes a higher rate of energy expenditure; however, one step climbing is energetically more expensive in total over the entirety of a stairway. Therefore to expend the maximum number of calories when climbing a set of stairs the single-step strategy is better.     

Effects of adenosine deaminase on the sensitivity of glucose transport, glycolysis and glycogen synthesis to insulin in muscles of the rat

1. Soleus, extensor digitorum longus (EDL) or hemi-diaphragm muscles of the rat were incubated in the presence of insulin and rates of the processes of glycolysis and glycogen synthesis were measured. 2. The concentrations of insulin required to cause half-maximal stimulation of glycolysis in both soleus and EDL preparations were significantly decreased by the presence of adenosine deaminase in the medium. 3. Adenosine deaminase increased the sensitivity of the process of hexose transport to insulin (in an identical manner to the change in sensitivity of glycolysis) in the EDL preparation. 4. None of the adenosine mediated effects on insulin-stimulated rates of glycolysis were observed in the hemi-diaphragm preparation or on the rates of glycogen synthesis in any of the three muscle preparations. 5. Therefore, changes in the adenosine system in skeletal muscle influence insulin sensitivity regardless of fibre type composition of the muscle.     

Effects of wheat germ agglutinin on tunicate egg activation and fertilization: Is there a plasma membrane sperm receptor system on Ascidia ceratodes eggs?

Little work has been carried out on the sperm recognition systems present on the egg plasma membrane. Here it is shown that wheat germ agglutinin (WGA) interferes with the sperm-interacting system on the plasma membrane of eggs of the ascidian, Ascidia ceratodes. The WGA activates the dechorionated egg, indicating that a plasma membrane sugar residue can be directly tied to egg activation. Low concentrations of this lectin do not activate the eggs, but reduce fertilizability. This observation suggests that the WGA binding site might be part of a sperm reception–activation complex in the plasma membrane. While WGA also affects sperm binding to the chorion, the mechanisms of sperm interaction at the plasma membrane and chorion show different sensitivities to lectins, sugars and enzymes.     

The distribution of mutagenic activity in red, rose and white wines

Using a modified Salmonella typhimurium TA98 Ames-test system, more than 150 red, white and rose wines were analyzed for direct-acting and microsomal enzyme-enhanced mutagenic activity. The following conclusions were reached from analysis of this wine mutagenicity data base. White and rose wines, as well as grape juices, exhibited little or no detectable direct-acting or microsomal enzyme-enhanced mutagenic activity. However, red wine samples contained highly variable amounts of mutagens, ranging from undetectable to levels 30-fold above the sensitivity limit of the assay system. The variations in red wine mutagenicity were unrelated to grape variety, vintage, aging methods or production region. Hence, individual winery production practices must represent the most significant contribution to the variations observed.