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High intensity interval training (HIIT) is known to be an effective exercise training regimen to improve energy substrate metabolism and insulin sensitivity. However, the underlying mechanisms of improvement in insulin sensitivity due to HIIT have not yet been fully clarified. C1q/TNF-related protein (CTRP) 1 and CTRP9, which are adiponectin paralogs and novel adipokines, have favorable effects on energy substrate metabolism and insulin sensitivity. The purpose of this study was to investigate the effects of a single bout of HIIT on CTRP1 and CTRP9 secretions in healthy men. Eight healthy male subjects (mean ± standard error: age, 23.4 ± 1.1 years; height, 172.1 ± 1.7 cm; body mass, 68.0 ± 2.0 kg; BMI, 22.9 ± 0.5 kg/m2) participated in this study. They performed a single bout of HIIT consisted of four 30-s maximal cycling bouts with 4-min rest between bouts using a cycle ergometer. Blood samples were collected before the exercise, at 0 (immediately after the exercise), 15, 30, and 120 min after the single bout of HIIT. Serum CTRP1, CTRP9, and high-molecular-weight (HMW) adiponectin concentrations were measured using enzyme-linked immunosolvent assay kits. CTRP1 concentration significantly increased at 120 min after the HIIT. CTRP9 concentration also significantly increased immediately after the single bout of HIIT. In contrast, there were no significant differences in HMW adiponectin concentration before and after the acute HIIT. These findings suggest that a single bout of HIIT may stimulate CTRP1 and CTRP9 secretions in healthy men.

The objective of this study was to develop a comprehensive dynamic model of the paddler, paddle and hull for a simulation analysis of the paddling motion in a single kayak. In the development of the model, a similar simulation model, not for the kayak, but for human swimming, was utilized. The paddler was represented as a series of 21 truncated elliptic cones. The paddle was represented as three truncated elliptic cones for the two blades and shaft. For the hull, an extension of the original simulation model to represent the detailed three-dimensional hull shape was carried out. In the extended hull model, the thin elliptic plate was replaced by a plate with a detailed cross-sectional shape. The paddler, paddle and hull in the model were connected by means of virtual springs and dampers. The geometries of the paddler, paddle and hull were acquired based on the experiments that measured them. The joint motion of the paddler was measured by means of motion analysis as well. By inputting the acquired data, simulation of the paddling motion was conducted. From the results, it was confirmed that the joint motion acquired in the experiment was successfully input into the simulation. It was also confirmed that the paddler, paddle and the hull were successfully connected by the virtual springs and dampers. In the simulation, the averaged velocity of the hull in the propulsive direction was 3.40 m/s, which was 11% lower than the actual value of 3.8 m/s.

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For achieving accurate and safe measurements of the force and power exerted on a load during resistance exercise, the Smith machine has been used instead of free weights. However, because some Smith machines possess counterweights, the equation for the calculation of force and power in this system should be different from the one used for free weights. The purpose of this investigation was to calculate force and power using an equation derived from a dynamic equation for a Smith machine with counterweights and to determine the differences in force and power calculated using 2 different equations. One equation was established ignoring the effect of the counterweights (Method 1). The other equation was derived from a dynamic equation for a barbell and counterweight system (Method 2). 9 female collegiate judo athletes performed bench throws using a Smith machine with a counterweight at 6 different loading conditions. Barbell displacement was recorded using a linear position transducer. The force and power were subsequently calculated by Methods 1 and 2. The results showed that the mean and peak power and force in Method 1 were significantly lower relative to those of Method 2 under all loading conditions. These results indicate that the mean and peak power and force during bench throwing using a Smith machine with counterweights would be underestimated when the calculations used to determine these parameters do not account for the effect of counterweights.

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