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Abstract Background Decreased oxygenation of muscle may be accentuated during exercise at high altitude. Monitoring the oxygen saturation of muscle (SmO2) during hand grip exercise using near infrared spectroscopy during acute exposure to hypoxia could provide a model for a test of muscle performance without the competing cardiovascular stresses that occur during a cycle ergometer or treadmill test. The purpose of this study was to examine and compare acute exposure to normobaric hypoxia versus normoxia on deoxygenation and recruitment of the flexor digitorum superficialis (FDS) during submaximal intermittent handgrip exercise (HGE) in healthy adults. Methods Twenty subjects (11 M/9 F) performed HGE at 50% of maximum voluntary contraction, with a duty cycle of 2 s:1 s until task failure on two occasions one week apart, randomly assigned to normobaric hypoxia (FiO2 = 12%) or normoxia (FiO2 = 21%). Near-infrared spectroscopy monitored SmO2, oxygenated (O2Hb), deoxygenated (HHb), and total hemoglobin (tHb) over the FDS. Surface electromyography derived root mean square and mean power frequency of the FDS. Results Hypoxic compared to normoxic HGE induced a lower FDS SmO2 (63.8 ± 2.2 vs. 69.0 ± 1.5, p = 0.001) and both protocols decreased FDS SmO2 from baseline to task failure. FDS mean power frequency was lower during hypoxic compared to normoxic HGE (64.0 ± 1.4 vs. 68.2 ± 2.0 Hz, p = 0.04) and both decreased mean power frequency from the first contractions to task failure (p = 0.000). Under both hypoxia and normoxia, HHb, tHb and root mean square increased from baseline to task failure whereas O2Hb decreased and then increased during HGE. Arterial oxygen saturation via pulse oximetry (SpO2) was lower during hypoxia compared to normoxia conditions (p = 0.000) and heart rate and diastolic blood pressure only demonstrated small increases. Task durations and the tension-time index of HGE did not differ between normoxic and hypoxic trials. Conclusion Hypoxic compared to normoxic HGE decreased SmO2 and induced lower mean power frequency in the FDS, during repetitive hand grip exercise however did not result in differences in task durations or tension-time indices. The fiber type composition of FDS, and high duty cycle and intensity may have contributed greater dependence on anaerobiosis.

Measuring the proximity of the body to the environment has the potential to provide rehabilitation health care professionals (RHCP) new, additional information to assess mobility. The aims of this study were to explore the opinions and needs of professionals to use a new device to measure such proximity, and to determine potential barriers and facilitators to implement it within the clinical setting. Four focus groups were conducted with 23 RHCP. The concept of a proximity measurement device in the early stages of development was introduced. A qualitative content analysis using a model of clinical utility as guidance for coding of the transcribed texts was used. Many potential uses were raised including: improving patient safety, motor learning, independence in tasks as gait, transfers and reaching tasks, saving time during assessment, improving follow-up with the client, data precision and objectivity to assess tasks. Barriers were related to still unclear relevance, effectiveness, the added value of such a device, and time required for use. The development of a turnkey device with support to facilitate its implementation was seen to be positive. These focus groups provided important information to further identify potential uses of such a device and to help to decrease barriers to its implementation.

Parkinson's disease (PD) is known to increase asymmetry and variability of bilateral movements. However, the mechanisms of such abnormalities are not fully understood. Here, we aimed to investigate whether kinematic abnormalities are related to cortical participation during bilateral, cyclical ankle movements, which required i) maintenance of a specific frequency and ii) bilateral coordination of the lower limbs in an anti-phasic manner. We analyzed electroencephalographic and electromyographic signals from nine men with PD and nine aged-matched healthy men while they sat and cyclically dorsi- and plantarflexed their feet. This movement was performed at a similar cadence to normal walking under two conditions: i) self-paced and ii) externally paced by a metronome. Participants with PD exhibited reduced range of motion and more variable bilateral coordination. However, participants with and without PD did not differ in the magnitude of corticomuscular coherence between the midline cortical areas and tibialis anterior and medial gastrocnemius muscles. This finding suggests that either the kinematic abnormalities were related to processes outside linear corticomuscular communication or PD-related changes in neural correlates maintained corticomuscular communication but not motor performance.