David B. McIntyre

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It is well established that performance is influenced by pressure, but the underlying mechanisms of the pressure-performance relationship are poorly understood. To address this important issue, the current experiment evaluated psychological, physiological, and kinematic factors as mediators of the pressure-performance relationship. Psychological,(More)
Carotid baroreceptor stimulation has been shown to dampen pain. This study tested, in 40 normotensive adults, the hypothesis that pain is lower during systole when arterial baroreceptor stimulation is maximal than diastole when stimulation is minimal. The sural nerve was stimulated electrocutaneously to obtain a nociceptive flexion reflex (NFR) threshold,(More)
Catastrophizing is reliably associated with increased reports of clinical and experimental pain. To test the hypothesis that catastrophizing may heighten pain experience by increasing nociceptive transmission through spinal gating mechanisms, the present study examined catastrophizing as a predictor of pain ratings and nociceptive flexion reflex (NFR)(More)
A model for phosphocreatine (PCr) resynthesis is proposed based on a simple electric circuit, where the PCr store in muscle is likened to the stored charge on the capacitor. The solution to the second-order differential equation that describes the potential around the circuit suggests the model for PCr resynthesis is given by PCr(t) = R - [d1.exp(-k1.t) +/-(More)
Slowing and loss of muscle power are major factors limiting physical performance but little is known about the molecular mechanisms involved. The slowing might be a consequence of slow detachment of cross bridges and, if this were the case, then a reduction in the ATP cost of an isometric contraction would be expected as the muscle fatigued. The human(More)
A baroreflex mechanism may explain hypertensive hypoalgesia. At rest, arterial baroreceptors are stimulated during the systolic upstroke of the pressure pulse wave. This study examined the effects of naturally occurring variations in baroreceptor activity during the cardiac cycle on an objective measure of pain, the nociceptive flexion reflex (NFR). Two(More)
Inhibition of the nociceptive flexion reflex during systole could be due to activation of the arterial baroreceptors. Physiological arousal, characterized by raised blood pressure, increases afferent activity from the arterial baroreceptors but attenuates the baroreflex. This study examined the effects of arousal on systolic inhibition of the nociceptive(More)
Knowledge of the psychophysiological responses that characterize optimal motor performance is required to inform biofeedback interventions. This experiment compared cortical, cardiac, muscular, and kinematic activity in 10 experts and 10 novices as they performed golf putts in low- and high-pressure conditions. Results revealed that in the final seconds(More)
The visceral afferent feedback hypothesis proposes that sensorimotor function is impaired by cortical inhibition associated with increased baroreceptor activation. This study is the first to examine the effects of naturally occurring variations in baroreceptor activity across the cardiac cycle on cutaneous sensory detection thresholds. In each trial, an(More)
It has been suggested that the reduced fatigability of muscles exercised at short length may result from a decrease in the metabolic cost of contractions in the shortened position. We compared the fatigue properties and metabolic cost of stimulated isometric tetanic contractions in the tibialis anterior of 10 normal subjects at the optimum length (Lo) for(More)