What limits [V(·)]O(2max)? A symposium held at the BASES Conference, 6 September 2010.

Three modern views about the factors limiting oxygen uptake in healthy humans are set against the original (early 1920s) concept of A. V. Hill and colleagues.

Effects of dynamic upper-body exercise on lower-limb isometric endurance.

Following preliminary indications that in some individuals arm exercise enhanced rather than reduced simultaneous leg endurance, ten young men and women performed three forms of intermittent work to volitional exhaustion, under duty cycles of 45 s work, 15 s rest. The protocols were as follows: (A) knee extensions at 30% maximum voluntary contraction (MVC); (B) 30% MVC knee extensions combined with arm cranking at 130% of their own lactate threshold; (C) combined 30% MVC knee extensions and arm cranking at 20% of their own lactate threshold. Heart rate, oxygen uptake (VO(2)), and blood lactate concentration were among the variables recorded throughout.

Hiking physiology and the "quasi-isometric" concept.

The literature indicates that the heart rate of a planing-dinghy sailor, in winds of 4 - 5 m . s(-1), is in the range seen in aerobic athletes, yet oxygen consumption (VO(2)) is roughly half that of the same individual cycling at that heart rate. Thus, although upper-body dynamic activity is a contributing factor, the dominant physiological demand must be the "quasi-isometric" stress on the lower-body anterior muscles - especially the quadriceps, which appears to impose 40 - 50% of the total oxygen demand in a typical hiking posture.

Indicators of maximal hiking performance in Laser sailors.

Laser class sailors have to hike out, i.e. hook their feet under the toe straps near the centreline of the boat and hold their upper bodies over the edge of the boat, to counteract the heeling forces generated by the sails.

The effect of strength training on the apparent inhibition of eccentric force production in voluntarily activated human quadriceps.

Ten male and ten female young adults trained the knee extensors of one leg eccentrically and those of the other concentrically for 6 weeks, using a gymnasium leg-extension machine. Before and after training, both legs of each subject were tested isometrically for maximum voluntary knee-extensor force, and in both eccentric and concentric isokinetic modes at 30-250 degrees x s(-1) All limbs showed improvements in mean eccentric force (ranging from 18% in the concentrically trained legs of the females to 31% in the eccentrically trained legs of the males, P < 0.01-0.

Quantitative skeletal muscle histochemistry of four east African ruminants.

A quantitative histochemical study was made of superficial thigh muscle specimens (semimembranosus and some vastus lateralis) from topi, hartebeest, wildebeest and waterbuck (species listed in order of increasing size). Fibres were largest (up to 120 microns diameter) in waterbuck but smallest (maximum approximately 90 microns) in wildebeest. Type 2B fibres, most of them large, highly glycolytic and weakly aerobic, constituted approximately 75% of the cross-section of topi specimens and approximately 83% of the others, greater area fractions than in other large herbivores.

Changes in ventilation related to changes in electromyograph activity during repetitive bouts of isometric exercise in simulated sailing.

This study examined the control of ventilation during repetitive bouts of isometric exercise in simulated sailing. Eight male sailors completed four successive 3-min bouts of similar isometric effort on a dinghy simulator; bouts were separated by 15-s rest intervals. Quadriceps muscle integrated electromyograph activity (iEMG) was recorded during each bout and expressed as a percentage of activity during maximal voluntary contraction (%iEMGmax).

Assessment of aerobic and anaerobic demands of dinghy sailing at different wind velocities.

The aim of this study was to assess the oxygen uptake (VO2), heart rate (HR) and blood lactate concentration ([Lab]) during actual dinghy sailing at different wind velocities. Eight top class Laser sailors volunteered to participate in the study. In the laboratory, each subject performed an incremental exercise test on a cycle ergometer to the point of exhaustion.

Aerobic exercise, anaerobic exercise and the lactate threshold.

All exercise draws first on intramuscular stores of ATP and creatine phosphate; initially these are replenished by anaerobic glycolysis. The lactic acid produced contributes to the rapid development of fatigue in high intensity exercise. Aerobic metabolism (at first mainly of glycogen, later increasingly of fat) is the principal route of ATP resynthesis in activities lasting longer than 2 min, but can only maintain work-rates about 1/4 of those possible in very brief bursts.

Quantitative analysis of histochemical and immunohistochemical reactions in skeletal muscle fibres of Rana and Xenopus.

Intensities of histochemical and immunohistochemical reactions in muscle fibres of Rana and Xenopus have been estimated microphotometrically, and the data from serial sections statically analysed. Quantitative validities of reactions and measurements have also been assessed against independent published evidence. It is concluded that NADH-tetrazolium reductase overestimates tonic-fibre aerobic capacities and the actomyosin ATPase reaction overestimates their contraction speeds.

A phosphorus nuclear magnetic resonance study of metabolites and intracellular pH in rabbit vascular smooth muscle.

1. 31P nuclear magnetic resonance (n.m.