Increased dietary carbohydrate and endurance during single-leg cycling using a limb with normal muscle glycogen concentration

The purpose of this study was to test the hypothesis that increased availability of blood-borne glucose would improve endurance after carbohydrate loading. A single-leg exercise model was employed, taking advantage of the fact that supercompensation of muscle glycogen occurs only in a previously exercised limb. Endurance time to exhaustion at 70% of maximal oxygen uptake (VO2 max) was determined for 11 males and three females who were then allocated to a control group or a high-carbohydrate (CHO) group. For 3 days following Test 1 the control group maintained a prescribed normal diet whilst the CHO group increased the proportion of energy derived from carbohydrate (62.1 +/- 4.3% cf. 43.9 +/- 2.0%, P less than 0.01). The endurance test was then repeated using the leg that was inactive during Test 1. Endurance time was increased on Test 2 (123.7 +/- 43.2 min cf. 98.5 +/- 21.9 min, P less than 0.05 one-tailed test) for the CHO group but not for the control group (101.8 +/- 21.7 min cf. 107.5 +/- 9.1 min, NS). There was no indication of enhanced carbohydrate metabolism during Test 2 for the CHO group but mean heart rate was lower during Test 2 than during Test 1 (145 +/- 14 beat min-1 cf. 152 +/- 12 beat min-1, P less than 0.05). These results suggest that the prior consumption of a high-carbohydrate diet improves endurance during high-intensity cycling with a limb with normal muscle glycogen concentration.     

Braided composite materials for the production of lightweight, high rigidity golf shafts

Braiding is not currently used in the production of golf shafts. The objective of this work was to develop, through a modelling process consisting of altering lamina sequence, a golf shaft, using braided laminas, which would have mass, stiffness and torque comparable to commercially available composite and steel shafts. A 2D conical braided composite model was previously developed and validated to predict elastic constants of braided closed meshed structures. Energy methods were used to calculate the stiffness and torque of shafts using prescribed industry approaches. Shaft mass was calculated based on geometry and density of constitutent materials. Modelled shafts had both braided and unidirectional layers and compared favourably with or were better than commercially available composite and steel shafts in terms of deflection force and twist angle; they had the same weight as composite shafts but were much lighter than steel shafts. If these findings are verified, braided composites would be a viable and effective approach to the design of future golf shafts.