Darren Burke

Creatine supplementation combined with resistance training in older men.

PURPOSE To study the effect of creatine (Cr) supplementation combined with resistance training on muscular performance and body composition in older men. METHODS Thirty men were randomized to receive creatine supplementation (CRE, N = 16, age = 70.4 +/- 1.6 yr) or placebo (PLA, N = 14, age = 71.1 +/- 1.8 yr), using a double blind procedure. Cr supplementation consisted of 0.3-g Cr.kg(-1) body weight for the first 5 d (loading phase) and 0.07-g Cr.kg(-1) body weight thereafter. Both groups participated in resistance training (36 sessions, 3 times per week, 3 sets of 10 repetitions, 12 exercises). Muscular strength was assessed by 1-repetition maximum (1-RM) for leg press (LP), knee extension (KE), and bench press (BP). Muscular endurance was assessed by the maximum number of repetitions over 3 sets (separated by 1-min rest intervals) at an intensity corresponding to 70% baseline 1-RM for BP and 80% baseline 1-RM for the KE and LP. Average power (AP) was assessed using a Biodex isokinetic knee extension/flexion exercise (3 sets of 10 repetitions at 60 degrees.s(-1) separated by 1-min rest). Lean tissue (LTM) and fat mass were assessed using dual energy x-ray absorptiometry. RESULTS Compared with PLA, the CRE group had significantly greater increases in LTM (CRE, +3.3 kg; PLA, +1.3 kg), LP 1-RM (CRE, +50.1 kg; PLA +31.3 kg), KE 1-RM (CRE, +14.9 kg; PLA, +10.7 kg), LP endurance (CRE, +47 reps; PLA, +32 reps), KE endurance (CRE, +21 reps; PLA +14 reps), and AP (CRE, +26.7 W; PLA, +18 W). Changes in fat mass, fat percentage, BP 1-RM, and BP endurance were similar between groups. CONCLUSION Creatine supplementation, when combined with resistance training, increases lean tissue mass and improves leg strength, endurance, and average power in men of mean age 70 yr.

Judging approachability on the face of it: The influence of face and body expressions on the perception of approachability

The aim of the current study was to examine how emotional expressions displayed by the face and body influence the decision to approach or avoid another individual. In Experiment 1, we examined approachability judgments provided to faces and bodies presented in isolation that were displaying angry, happy, and neutral expressions. Results revealed that angry expressions were associated with the most negative approachability ratings, for both faces and bodies. The effect of happy expressions was shown to differ for faces and bodies, with happy faces judged more approachable than neutral faces, whereas neutral bodies were considered more approachable than happy bodies. In Experiment 2, we sought to examine how we integrate emotional expressions depicted in the face and body when judging the approachability of face-body composite images. Our results revealed that approachability judgments given to face-body composites were driven largely by the facial expression. In Experiment 3, we then aimed to determine how the categorization of body expression is affected by facial expressions. This experiment revealed that body expressions were less accurately recognized when the accompanying facial expression was incongruent than when neutral. These findings suggest that the meaning extracted from a body expression is critically dependent on the valence of the associated facial expression.

Coherent Perspective Jitter Induces Visual Illusions of Self-Motion:

Palmisano et al (2000 Perception 29 57–67) found that adding coherent perspective jitter to constant-velocity radial flow improved visually induced illusions of self-motion (vection). This was a surprising finding, because unlike pure radial flow, this jittering radial flow should have generated sustained visual–vestibular conflicts—previously thought to always reduce/impair vection. We attempted to ascertain the essential stimulus features for this jitter advantage for vection by examining three novel types of jitter display. While adding incoherent jitter to radial flow was found to impair vection, adding coherent non-perspective jitter had little effect on this subjective experience (contrary to the notion that jitter improves vection by reducing adaptation to radial flow). Importantly, we found that coherent perspective jitter not only improves the vection induced by radial flow, but it also appears to induce modest vection by itself (demonstrating that vection can still occur when there is an extreme mismatch between actual and expected vestibular activity). These results suggest that the previously demonstrated advantage for coherent perspective jitter was due (in part at least) to jittering vection combining with forwards vection in depth to produce a more compelling overall vection experience.

The effect of interactions between one-dimensional component gratings on two-dimensional motion perception

Ferrera and Wilson [(1990) Vision Research, 30, 273-287] reported veridical perception of the direction of motion of Type I plaids, whose component gratings span the resultant direction, but marked misperception of the direction of motion of Type II plaids, whose component gratings both lie on one side of the resultant direction. Because they failed to find any effect of component direction (angular) separation on this misperception, Ferrera and Wilson concluded that the misperception was not due to perceptual repulsion of component directions. We report that component direction repulsion does occur, that plaid direction misperception is tuned to component separation, with larger repulsions for smaller angles. It is concluded that there is no fundamental difference in direction coding for Type I and Type II plaids, and that Ferrera and Wilson failed to find a direction separation effect because the range of separations they used was insufficiently broad to detect the slope of the angular function.

Evidence that identity-dependent and identity-independent neural populations are recruited in the perception of five basic emotional facial expressions.

Major cognitive and neural models of face perception view that the mechanisms underlying the extraction of facial expression and facial identity information involve separable visual systems. Using the visual adaptation paradigm, we explored the sensitivity of happy, sad, angry, disgusted and fearful facial expressions to changes in identity. Contrary to what would be predicted by traditional face perception models, larger expression aftereffects were produced when the identity of the adapting and test stimuli was the same compared to when the identity differed, suggesting the involvement of identity-dependent neurons in processing these expressions. Furthermore, for all five expressions, the aftereffects remained significant when the adapting and test stimuli differed in identity, suggesting the involvement of identity-independent neural populations. The extent to which the aftereffect transferred across changes in identity was the same for all emotional expressions. Consequently, there is no evidence that the processing of individual facial expressions depend on facial identity differentially. Implications of these findings are discussed.

An evolved spatial memory bias in a nectar-feeding bird?

Studies have shown that nectar-feeding birds more easily learn to avoid a previously rewarding location (to win-shift) than to return to such a location (to win-stay). This pattern has been interpreted as evidence of an evolved adaptation to the fact that nectar is a depleting resource; however, such a conclusion requires ruling out the possibility that this tendency is a consequence of the experience of individual birds, and is more compelling if performance in the memory task reveals sensitivity to detailed features of the spatiotemporal distribution of nectar in the environment. We tested the tendency of captive-reared Regent honeyeaters, Xanthomyza phrygia, a species of nectar-feeding bird, to win-shift or win-stay at different intervisit intervals. The birds generally avoided rewarding locations after a short retention interval (10 min), but returned to these locations after a long retention interval (3 h). This behaviour tracks the replenishment rate of the flowers exploited by this species in the wild, even though the subjects were born and reared in captivity.

Orbitofrontal cortex lesions result in abnormal social judgements to emotional faces

Facial expressions of emotion display a wealth of important social information that we use to guide our social judgements. The aim of the current study was to investigate whether patients with orbitofrontal cortex (OFC) lesions exhibit an impaired ability to judge the approachability of emotional faces. Furthermore, we also intended to establish whether impaired approachability judgements provided to emotional faces emerged in the presence of preserved explicit facial expression recognition. Using non-parametric statistics, we found that patients with OFC lesions had a particular difficulty using negative facial expressions to guide approachability judgements, compared to healthy controls and patients with frontal lesions sparing the OFC. Importantly, this deficit arose in the absence of an explicit facial expression recognition deficit. In our sample of healthy controls, we also demonstrated that the capacity to recognise facial expressions was not significantly correlated with approachability judgements given to emotional faces. These results demonstrate that the integrity of the OFC is critical for the appropriate assessment of approachability from negatively valenced faces and this ability is functionally dissociable from the capacity to explicitly recognise facial expressions.

Are face representations viewpoint dependent? A stereo advantage for generalising across different views of faces

Almost all previous studies of face recognition have found that matching the same face depicted from different viewpoints incurs both reaction time and accuracy costs. This has been interpreted as evidence that the underlying neural representations of faces are viewpoint-specific, but such a conclusion depends on the experimental data being an accurate reflection of real-world viewpoint generalisation. An equally plausible explanation for poor viewpoint generalisation in experimental situations is that important information that is normally used to generalize across views in real-world settings is not available in the experiment. Stereoscopic information about the three-dimensional structure of the face is systematically misleading in nearly all previous investigations of face recognition, since a face depicted on a computer monitor contains explicit stereoscopic information that the face is flat. The current experiment demonstrates that viewpoint costs are reduced by depicting the face with stereoscopic three-dimensionality (compared to a synoptically presented face), raising the possibility that the viewpoint costs found in face recognition experiments might be a better reflection of the information that is typically unavailable in the experimental stimuli than of the underlying neural representation of facial identity.

Effect of creatine supplementation during cast-induced immobilization on the preservation of muscle mass, strength, and endurance.

Johnston, APW, Burke, DG, MacNeil, LG, and Candow, DG. Effect of creatine supplementation during cast-induced immobilization on the preservation of muscle mass, strength, and endurance. J Strength Cond Res 23(1): 116-120, 2009-Muscle and strength loss will occur during periods of physical inactivity and immobilization. Creatine supplementation may have a favorable effect on muscle mass and strength independently of exercise. The purpose of this study was to determine the effects of creatine supplementation on upper-limb muscle mass and muscle performance after immobilization. Before the study, creatine-naïve men (n = 7; 18-25 years) were assessed for lean tissue mass (dual-energy X-ray absorptiometry), strength (1-repetition maximum [1RM] isometric single arm elbow flexion/extension), and muscle endurance (maximum number of single-arm isokinetic elbow flexion/extension repetitions at 60% 1RM). After baseline measures, subjects had their dominant or nondominant (random assignment) upper limb immobilized (long arm plaster cast) at 90° elbow flexion. Using a single-blind crossover design, subjects received placebo (maltodextrin; 4 × 5 g·d−1) during days 1-7 and creatine (4 × 5 g·d−1) during days 15-21. The cast was removed during days 8-14 and 22-29. The dependent measures of lean tissue mass, strength, and endurance were assessed at baseline, postcast, and after the study. During immobilization, compared with isocaloric placebo, creatine supplementation better maintained lean tissue mass (Cr +0.9% vs. PLA −3.7%, p < 0.05), elbow flexor strength (Cr −4.1% vs. PLA −21.5%, p < 0.05), and endurance (Cr −9.6% vs. PLA −43%, p < 0.05), and elbow extensor strength (Cr −3.8% vs. PLA −18%, p < 0.05) and endurance (Cr −6.5% vs. PLA −35%, p < 0.05). These results indicate that short-term creatine supplementation attenuates the loss in muscle mass and strength during upper-arm immobilization in young men.

A New Viewpoint on the Evolution of Sexually Dimorphic Human Faces

Human faces show marked sexual shape dimorphism, and this affects their attractiveness. Humans also show marked height dimorphism, which means that men typically view womens faces from slightly above and women typically view mens faces from slightly below. We tested the idea that this perspective difference may be the evolutionary origin of the face shape dimorphism by having males and females rate the masculinity/femininity and attractiveness of male and female faces that had been manipulated in pitch (forward or backward tilt), simulating viewing the face from slightly above or below. As predicted, tilting female faces upwards decreased their perceived femininity and attractiveness, whereas tilting them downwards increased their perceived femininity and attractiveness. Male faces tilted up were judged to be more masculine, and tilted down judged to be less masculine. This suggests that sexual selection may have embodied this viewpoint difference into the actual facial proportions of men and women.