Aging exaggerates blood pressure response to ischemic rhythmic handgrip exercise in humans.

Ischemic skeletal muscle conditions are known to augment exercise-induced increases in blood pressure (BP). Aging is also a factor that enhances the pressor response to exercise. However, the effects of aging on the BP response to ischemic exercise remain unclear.

Inhalation of molecular hydrogen increases breath acetone excretion during submaximal exercise: a randomized, single-blinded, placebo-controlled study.

Aerobic exercise is widely accepted as a beneficial option for reducing fat in humans. Recently, it has been suggested that molecular hydrogen (H) augments mitochondrial oxidative phosphorylation. Therefore, the hypothesis that inhaling H could facilitate lipid metabolism during aerobic exercise was investigated in the current study by measuring the breath acetone levels, which could be used as non-invasive indicators of lipid metabolism.

Does degree of alteration in effort sense caused by eccentric exercise significantly affect initial exercise hyperpnea in humans?

Previous research has shown an exaggeration in exercise hyperpnea 2 days after eccentric exercise (ECC). Enhancement in central command has been suggested as one candidate to account for this effect given that ECC-induced neuromuscular dysfunction increases relative exercise intensity, thus resulting in reinforcement of effort sense. The purpose of this study was, therefore, to elucidate whether the degree of alteration in effort sense caused by ECC affects exercise hyperpnea.

Degree of exercise intensity during continuous chest compression in upper-body-trained individuals.

Background: Although chest-compression-only cardiopulmonary resuscitation (CCO-CPR) is recommended for lay bystanders, fatigue is easily produced during CCO-CPR. If CCO-CPR can be performed at a lower intensity of exercise, higher resistance to fatigue is expected. Since chest compression is considered to be a submaximal upper body exercise in a steady rhythm and since the unit of load for chest compression is expressed as work rate, we investigated the possibility that peak work rate of the upper body determines the level of exercise intensity during CCO-CPR.

Higher ventilatory responses during and after passive walking-like leg movement in older individuals.

Background: Minute ventilation (V · E) during walking has been shown to be higher in older individuals than in young individuals, but the mechanisms underlying the higher ventilatory response is unclear. Central command and peripheral neural reflex are important neural control mechanisms underlying ventilatory response during exercise. Passive leg movement has been used to exclude the influence of central command due to the lack of voluntary activation of muscles.

Suppression of cardiocirculatory responses to orthostatic stress by passive walking-like leg movement in healthy young men.

Background: Although passive walking-like leg movement in the standing posture (PWM) has been used in the clinical field, the safety of PWM has not been fully determined despite the risks of orthostatic intolerance due to standing posture. The aim of the present study was to examine cardiocirculatory response during PWM in healthy young men.

Methods: The subjects (n = 13) spent 5 min in a sitting position and then 5 min in a quiet standing position to determine baseline levels.

Limb oxygenation during the cold pressor test in spinal cord-injured humans.

Objective: To investigate changes in tissue oxygenation in the arm and leg during the cold pressor test in humans with spinal cord injury (SCI).

Methods: Subjects with SCI at cervical 6 (n=7) and subjects with SCI at thoracic 5 or thoracic 6 (n=5) experienced 3-min cold water immersion of the foot and subsequent 10-min recovery. Changes in tissue oxygenation and blood pressure were determined.

Hypoventilation during passive leg movement in spinal cord-injured humans.

We examined ventilatory response during passive walking-like exercise in the standing posture in complete spinal cord-injured humans and found that ventilatory equivalent for O(2) uptake, which would be related to the sensation of breathlessness, was lower during passive exercise than during quiet standing.

Unusual blood pressure response during standing therapy in tetraplegic man.

We report a case of an individual with cervical spinal cord injury who showed a unique blood pressure response during passive standing and passive walking-like leg movement, i.e., hypertension with standing and hypotension with leg movement.

Hyperventilation during orthostatic challenge in spinal cord-injured humans.

Objective: To determine whether arterial hypotension is related to hyperventilation during standing in individuals with complete spinal cord injury (SCI).

Methods: Sixteen individuals with SCI (thoracic 1 to thoracic level 12, ASIA grade: A) and 18 able-bodied individuals participated in this study. Individuals with SCI were divided into a group with injury level at or above thoracic (T) 7 [higher SCI (HSCI), n = 9] and a group with injury level at or below T10 (lower SCI, n = 7).

Pressor response to passive walking-like exercise in spinal cord-injured humans.

Objective: To examine blood pressure responses during passive walking-like exercise in the standing posture (PWE) in spinal cord-injured (SCI) humans.

Methods: Twelve motor-complete SCI individuals (cervical level 6 to thoracic level 12, ASIA grade: A or B) and twelve able-bodied controls (CON) participated in this study. SCI individuals were divided into a group with injury level at or above thoracic (T) 6 (HSCI, n = 7) and a group with injury level at or below T10 (LSCI, n = 5).

Invariable H-reflex and sustained facilitation of stretch reflex with heightened sympathetic outflow.

Stretch reflex shows sustained (3-min) increase with heightened sympathetic outflow [Hjortskov N, Skotte J, Hye-Knudsen C, Fallentin N. Sympathetic outflow enhances the stretch reflex response in the relaxed soleus muscle in humans. J Appl Physiol 2005;98:1366-70], but it is unknown if it accompanies a sustained increase in H-reflex.

Metaboreceptor-mediated muscle oxygen saturation during recovery following isometric handgrip exercise.

The aim of the present study was to determine whether oxygen supply to non-exercised muscle during recovery following fatiguing exercise is influenced by accumulated metabolites within exercised muscle. Twelve healthy male subjects performed 2-min isometric handgrip exercise at 40% maximal voluntary contraction with their right hand and the exercise was followed by a 3-min recovery period. Muscle oxygen saturation (SmO(2)) determined by near-infrared spatially resolved spectroscopy was used as an index of oxygen supply to non-exercised muscle and was measured in biceps brachii and tibialis anterior muscles on the left side.

Effects of passive leg movement on the oxygenation level of lower limb muscle in chronic stroke patients.

Objective: To evaluate the effects of passive leg movements on the muscle oxygenation level and electromyographic (EMG) activity in the lower limbs in chronic stroke patients.

Methods: With a gait training apparatus, passive movements were imposed on the lower limbs of 15 chronic stroke patients at a frequency of 0.8 Hz for 10 minutes.

A 350-S recovery period does not necessarily allow complete recovery of peak power output during repeated cycling sprints.

The aim of this study was to determine whether a 350-s recovery period allows recovery of peak power output (PPO) to its initial value under the condition of a blood lactate (La) concentration higher than 10 mmol.L-1 during repeated cycling sprints (RCS). RCS (10x10-s cycling sprints) were performed under two conditions.

Effect of blood lactate concentration and the level of oxygen uptake immediately before a cycling sprint on neuromuscular activation during repeated cycling sprints.

The purpose of this study was to determine whether neuromuscular activation is affected by blood lactate concentration (La) and the level of oxygen uptake immediately before a cycling sprint (preVO(2)). The tests consisted of ten repeated cycling sprints for 10 sec with 35-sec (RCS(35)) and 350-sec recovery periods (RCS(350)). Peak power output (PPO) was not significantly changed despite an increase in La concentration up to 12 mmol/L in RCS(350).

Kinetics of oxygen uptake during arm cranking with the legs inactive or exercising at moderate intensities.

The purpose of this study was to compare the kinetics of oxygen uptake (VO(2)) during arm cranking with the legs inactive or exercising. Each subject (n = 8) performed three exercise protocols: 6-min arm cranking at an intensity of 60% of peak oxygen uptake (VO(2peak), AC(60)) and 6-min combined arm cranking and leg cycling in which AC(60) was added to on-going leg cycling at an intensity of 20% or 40% of VO(2peak) (LC(20) and LC(40): AC(60)LC(20) and AC(60)LC(40), respectively). After the onset of arm cranking, VO(2) tended to increase until the end of arm cranking in all of the three exercise modes.

Kinetics of oxygenation in inactive forearm muscle during ramp leg cycling.

This study was carried out to determine whether hemodynamics in inactive forearm muscle during ramp leg cycling is affected from the ventilatory threshold (VT) and respiratory compensation point (RCP), at which the rate of increase in ventilation (VE) against power output begins to increase abruptly. Change in hemodynamics was evaluated by change in oxygenation index (difference between concentrations of oxygenated hemoglobin and deoxygenated hemoglobin, HbD) measured using near-infrared spectrometry (NIRS). Each subject (n=9) performed 4-min constant-work-rate leg cycling and subsequent ramp leg cycling at an increasing rate of 10 watts.

Approximation equation for oxygen uptake kinetics in decrement-load exercise starting from low exercise intensity.

The purpose of the present study was to determine the degree of fitting an approximation equation for oxygen uptake (Vo(2)) in decrement-load exercise (DLE). Work rate was started from 120 watts and was decreased by a rate of 15 watts per min. The initial work rate of DLE corresponded to 72+/-10% of the work rate at anaerobic threshold determined in incremental-load exercise (ILE).

Relationship in simulation between oxygen deficit and oxygen uptake in decrement-load exercise starting from low exercise intensity.

The purpose of the present study was to determine by simulation whether oxygen deficit kinetics in decrement-load exercise (DLE) starting from a low exercise intensity is related to the oxygen uptake (Vo(2)) kinetics. In this simulation, work rate in DLE was separated into steps that were regarded as constant-load exercises (CLEs). It was assumed that Vo(2) kinetics behaved exponentially at the onset and offset of each CLE, respectively.