Fluid type influences acute hydration and muscle performance recovery in human subjects.

Background: Exercise and heat trigger dehydration and an increase in extracellular fluid osmolality, leading to deficits in exercise performance and thermoregulation. Evidence from previous studies supports the potential for deep-ocean mineral water to improve recovery of exercise performance post-exercise. We therefore wished to determine whether acute rehydration and muscle strength recovery was enhanced by deep-ocean mineral water following a dehydrating exercise, compared to a sports drink or mountain spring water.

The impact of post-exercise hydration with deep-ocean mineral water on rehydration and exercise performance.

Background: Dehydration caused by prolonged exercise impairs thermoregulation, endurance and exercise performance. Evidence from animal and human studies validates the potential of desalinated deep-ocean mineral water to positively impact physiological and pathophysiological conditions. Here, we hypothesize that deep-ocean mineral water drawn from a depth of 915 m off the Kona, HI coast enhances recovery of hydration and exercise performance following a dehydrating exercise protocol compared to mountain spring water and a carbohydrate-based sports drink.

Short-term synchrony in diverse motor nuclei presumed to receive different extents of direct cortical input.

Motor units within human muscles usually exhibit a significant degree of short-term synchronization. Such coincident spiking typically has been attributed to last-order projections that provide common synaptic input across motor neurons. The extent of branched input arising directly from cortical neurons has often been suggested as a critical factor determining the magnitude of short-term synchrony.

Evaluation of plateau-potential-mediated 'warm up' in human motor units.

Spinal motor neurones can exhibit sustained depolarization in the absence of maintained synaptic or injected current. This phenomenon, referred to as a plateau potential, is due to the activation of monoamine-dependent persistent inward currents. Accordingly, activation of a plateau potential should result in a decrease in the excitatory synaptic drive required to activate a motor unit.

Distribution of motor unit force in human extensor digitorum assessed by spike-triggered averaging and intraneural microstimulation.

A peculiar aspect of the muscular organization of the human hand is that the main flexors and extensors of the fingers are muscles that each give rise to four parallel tendons that insert on all the fingers. It has been hypothesized that these multi-tendoned muscles are comprised of functional compartments, with each finger controlled by a discrete population of motor units. The purpose of this study was to determine the force distribution across the four fingers for motor units in human extensor digitorum (ED), a multi-tendoned muscle that extends the fingers.

Role of intertendinous connections in distribution of force in the human extensor digitorum muscle.

The human extensor digitorum (ED) muscle gives rise distally to multiple tendons that insert onto and extend digits 2-5. It has been shown previously that the spike-triggered average forces of motor units in ED are broadly distributed across many tendons. Such force dispersion may result from linkages between the distal tendons of ED and may limit the ability to move the fingers independently.

Common input to motor neurons innervating the same and different compartments of the human extensor digitorum muscle.

Short-term synchronization of active motor units has been attributed in part to last-order divergent projections that provide common synaptic input across motor neurons. The extent of synchrony thus allows insight as to how the inputs to motor neurons are distributed. Our particular interest relates to the organization of extrinsic finger muscles that give rise distally to multiple tendons, which insert onto all the fingers.

Re-evaluation of muscle wisdom in the human adductor pollicis using physiological rates of stimulation.

Motor unit discharge rates decline by about 50 % over 60 s of a sustained maximum voluntary contraction (MVC). It has been suggested that this decline in discharge rate serves to maintain force by protecting against conduction failure and by optimizing the input to motor units as their contractile properties change. This hypothesis, known as muscle wisdom, is based in part on studies in which muscle force was shown to decline more rapidly when stimulation was maintained at a high rate than when stimulus rate was reduced over time.