No abstract

Rock climbing is a popular adventure sport with an increasing research base. Early studies in the field did not make comparisons of ascents using different styles of climbing. More recently, differences in the physiological responses for an onsight lead climb and subsequent lead climb have been reported. The purpose of the present study was to examine the effect of style of climb (lead climb or top rope climb) on the physiological and psychological responses to rock climbing. Nine intermediate climbers volunteered for, and completed, two randomly assigned climbing trials and a maximum oxygen uptake (VO 2max ) test on a separate occasion. The climbers ascended the same 6a (sport grade) climb for both trials. Before climbing, heart rate, perception of anxiety (Revised Competitive State Anxiety Inventory-2), and blood lactate concentration were measured. Climb time, heart rate, VO 2 , lactate concentrations, and task load (National Aeronautics and Space Administration Task Load Index) in response to each trial were also recorded. Results indicated significant differences (PB0.05) between the trials for climb time, blood lactate concentration immediately after and 15 min after climbing, and heart rate 1 min after climbing. During lead and top rope climbing, mean VO 2 and represented 44% and 42% of treadmill VO 2max and mean heart rate represented 81% and 77% of maximum heart rate, respectively. There were no significant differences in feelings of anxiety before either climb, although climbers reported the lead climb to be physically and mentally more demanding, requiring more effort and resulting in greater frustration (P B0.05) than the top rope climb. Our results indicate that the physiological and psychological responses of intermediate climbers are different for a lead climb and top rope climb.

Objectives: To examine how different safety rope protocols impact on subjective anxiety and self-confidence levels and plasma cortisol concentrations and the relationship between subjective states and cortisol during rock climbing. Methods: Participants (n = 12) were tested in three climbing conditions that were designed to invoke low, moderate and high physical and mental stress. Plasma cortisol concentrations were collected before and after climbing and participants reported subjective anxiety and self-confidence states for each climb.Results: Repeated measures analysis of variance showed significant differences between conditions for somatic anxiety (F 2, 22 = 7.74, p = 0.009), self-confidence (F 2, 22 = 9.52, p = 0.001) and change in plasma cortisol concentration (F 2, 22 = 3.71, p = 0.041). Preplanned polynomial comparisons showed that these were linear effects; somatic anxiety was higher in the higher stress conditions whilst self-confidence was lower. Plasma cortisol concentration change was also linear. Regression analyses showed cubic relationships between plasma cortisol concentration and cognitive anxiety (R 2 = 0.452), self-confidence (R 2 = 0.281) and somatic anxiety (R 2 = 0.268). Conclusions: There is a relationship between plasma cortisol concentration and subjective anxiety and selfconfidence states during rock climbing. Changes in the way the safety rope is organised can impact on anxiety, cortisol concentration and self-confidence during rock climbing.

Interest in the imidazole dipeptides (ImD) has increased in response to data showing elevated levels following b-alanine supplementation have improved athletic performance (1) and have anti-senescent effects (2) . The diet can provide a variety of sources of ImD, predominately anserine and carnosine. Previous analyses of ImD sources have primarily measured the ImD content of meat from aquatic mammals and game foods (3,4) , which are not commonly consumed within the British diet (5) . Therefore, calculation of ImD content provided by the British diet requires the measurement of reference values for the most commonly consumed foods within the diet.This study analysed triplicates of 10 commonly consumed foods within the British diet selected from the NDNS (5) to develop reference values to calculate ImD intake. So as samples were representative of the same quality (age, storage procedures) as those consumed within the general diet, samples were obtained from both supermarkets and specialist retailers. Thus samples encapsulated those that can be purchased across the socio-economic spectrum. Samples (n 3 · 10 mg) were obtained from core biopsies from three samples of each food (n 9 for each food measured) and were freeze-dried before being extracted in methanol :borate and analysed via HPLC (6) for their anserine and carnosine content.

The histidine-containing dipeptides (HCD) carnosine and anserine are found in high concentrations in mammalian skeletal muscle. Given its versatile biologic properties, such as antioxidative, antiglycation, and pH buffering capacity, carnosine has been implicated as a protective factor in the aging process. The present study aimed to systematically explore age-related changes in skeletal muscles HCD content in a murine model of accelerated aging. Additionally, we investigated the effect of lifelong creatine supplementation on muscle HCD content and contractile fatiguability. Male senescence-accelerated mice (SAMP8) were fed control or creatine-supplemented (2% of food intake) diet from the age of 10 to 60 weeks. At week 10, 25, and 60, tibialis anterior muscles were dissected and analysed for HCD and taurine content by HPLC. Soleus and EDL muscles were tested for in vitro contractile fatigue and recovery. From 10 to 60 weeks of age, muscular carnosine (-45%), taurine (-24%), and total creatine (-42%) concentrations gradually and significantly decreased. At 25 but not at 60 weeks, oral creatine supplementation significantly increased carnosine (+88%) and anserine (+40%) content compared to age-matched control-fed animals. Taurine and total creatine content were not affected by creatine supplementation at any age. Creatine-treated mice showed attenuated muscle fatigue (soleus) and enhanced force recovery (m. extensor digitorum longus [EDL]) compared to controls at 25 weeks, but not at 60 weeks. From the present study, we can conclude that skeletal muscle tissue exhibits a significant decline in HCD content at old age. Oral creatine supplementation is able to transiently but potently increase muscle carnosine and anserine content, which coincides with improved resistance to contractile fatigue.

The advantages of the electrostatic interpretation of chemical bincling are illustrated. It is show11 that the forces exerted by the electrons in a molecular orbital may be determined by general expressions. These are functions of only one parameter, the value of which is easily specified for a particular case. From the genera1 expressions it is possible to obtain quantitative measures of the bonding or antibonding power of a molecular orbital. It is shown that the usual interpretations of bonding and antibonding properties in molecular orbital theory arc misleading and that few orbitals are, in actual fact, arltibonding. If molecular orbitals are classified as net bonding or net antibonding, terms which are precisely defined and have a definite physical significance, a much closer correlation with previous concepts of bonding is obtained. The effects of mutual ortl~ogonalization within a set of orbitals are studied. I t is found that this procedure decreases the bonding ability of bonding orbitals, but increases that of antibonding orbitals. The dangers of disregarding such orthogonalization in a conventional calculation are clearly illustrated. I. INTRODUC'I'IONThe FIellmann-Feyn~~~an theorem permits one to relate the forces acting on a nucleus in a molecule to the classical electrostatic forces exerted on the nucleus by the other nuclei and by the particular distribution of electrons found in the nlolecule. This relationship may be expressed as where p(x, y, z,) is the electron density, ~y~, the electric field produced by the at11 ilucleus in the x direction a t the position of the it11 electron, and 2, is the nuclear charge of atom a. In a previous paper ( I ) we have shown that equation [ I ] is capable of providing reasonable results for the binding energies of simple molecules. At that time it was stated that the Hellmann-Feynman theorem provides a qualitative interpretation of chemical binding that is perhaps more readily understandable than is the usual discussion which is couched in terms of energies. The reason for this is that the electron density present in a molecule is a real three-dimensional quantity. In employing the I-Iellmann-Feynlnan theorem one reduces a problem in molecular structure to a problem in classical electrostatics, a problem of the interaction of a system of nuclei and some continuous charge distribution. In this paper we wish to illustrate the advantages of this approach. Rather than press the Hellmann-Feynman theorem by attempting to calculate molecular energies through the use of approxin~ately determined electron densities, we \visl~ instead to demonstrate the ability of the theorem to provide us with useful semiquantitative results regarding the bonding character of various electron distributions. T H E HEL1,MANN-FEYNMAN THEOREM A N D T H E MOLECULXIP OliRIrTi\l. APPROACHWhen the molecular orbitals used in the description of the electronic structure o l a ~nolecule are all orthonormal, the electron density may be expressed as For personal use only. the occupatioil n...

An electron-density distribution is determined for the ammonia molecule in its equilibrium configuration by requiring the distribution to exert forces on the nuclei equal and opposite to the nuclear forces of repulsion. The density distribution so obtained is compared with those determined by SCF calculations. All of the density functions are tested by comparing the calculated and observed values for the following molecular properties: (i) the forces on the nuclei, (ii) the dipole moment, (iii) the electric-field gradient at the nitrogen nucleus, (iv) the diamagnetic susceptibility, and (v) the diamagnetic contribution to the nuclear shielding constant.

The electron density distribution for the water molecule in its equilibrium configuration is determined by requiring that the forces exerted on the nuclei by this distribution (as calculated by the Hellmann-Feynman theorem) balance the nuclear forces of repulsion. The density distribution is expressed in terms of equivalent orbitals, and to achieve electrostatic equilibrium it is found necessary to have an angle between the bonding orbitals which is less than the structural bond angle (bent bonds), to delocalize the equivalent orbitals and to place the lone pair electrons in sp hybrid orbitals. Further, a discussion of the forces operative in XH2 and XHI molecules (X = C, N, 0 ) leads to an explanation of the observed bond angles and to general conclusions regarding the hybridization to be expected in such molecules.