Validity of anaerobic threshold measured in resistance exercise.

[Purpose] Intensity for resistance exercise is estimated based on the maximum muscle strength. Exercise prescription without evaluating the biological response has a challenge. This study aimed to confirm whether anaerobic threshold measured using cardiopulmonary exercise test in resistance exercise is appropriate or not. [Participants and Methods] Resistance exercise adopted for the study was right-leg knee extension. The participants were 10 healthy young males. We investigated whether the oxygen uptake kinetics achieved a steady state within 3 min during the constant-load test with knee extension at 80% anaerobic threshold using cardiopulmonary exercise test with knee extension. If oxygen uptake kinetics achieved a steady state within 3 min, the exercise intensity measured using cardiopulmonary exercise test was considered appropriate. [Results] Anaerobic threshold was measured using the conventional approach in all participants. The steady state of oxygen uptake kinetics could be achieved within 3 min. In the constant-load test with knee extension at 80% anaerobic threshold, the oxygen uptake kinetics achieved a steady state within 3 min. [Conclusion] Based on the findings, the anaerobic threshold obtained using cardiopulmonary exercise test with resistance exercise was judged as appropriate. The results of this study contribute to the accurate setting of exercise load for resistance exercise and condition setting for the evaluation of skeletal muscle function.

Minimum detectable change in reaction time to the Posner task due to change in sustained attention.

[Purpose] Spatial attention evaluations are beneficial for patients with unilateral spatial neglect or dementia. Thus, such evaluations are crucial among these patients for determining functional disorder extents. The study aimed to determine minimal detectable changes in reaction time to the Posner task among healthy young participants for establishing spatial attention evaluation protocols. [Participants and Methods] The study recruited 10 healthy young adults (five males and five females; mean age: 28.9 ± 4.0 years). Each participant completed two sessions of the Posner task with 160 trials per session. The reaction time for each trial was measured. Data obtained by the two blocks were analyzed by Bland-Altman analysis, and intraclass correlation coefficient case 1 and minimal detectable changes at the 95% confidence interval were calculated. [Results] Bland-Altman analysis indicated no systematic bias. The intraclass correlation coefficient case 1 exceeded 0.80 under all conditions of the Posner task, whereas the minimal detectable changes at the 95% confidence interval spanned 23-34 ms. [Conclusion] The results exhibited high reliability for reaction time to the Posner task. The minimal detectable changes as the 95% confidence interval values determined in this study based on reaction time can be applied to establish spatial attention evaluation protocols.

Effect of cold oral stimulation on orthostatic hypotension in multiple system atrophy: a case study.

[Purpose] The aim of this case study is to reconsider the method for preventing orthostatic hypotension in multiple system atrophy. [Participant and Methods] The case was that of a 70-year-old female with multiple system atrophy who experienced frequent falls and orthostatic hypotension. An orthostatic test was performed, and the effect of cold oral stimulation before standing was compared with no stimulation. Outcome measures were blood pressure, heart rate variability and autonomic variables. [Results] In the control test, blood pressure decreased from 150/72 mmHg in the supine position to 98/58 mmHg in the standing position. Heart rate increased from 71 bpm to 82 bpm, high frequency declined from 16.48 msec2 to 14.07 msec2, and low/high frequency increased from 2.56 to 5.13. Cold stimulation in the standing position induced changes in blood pressure from 168/82 mmHg to 104/72 mmHg, heart rate from 73 bpm to 83 bpm, high frequency from 61.29 msec2 to 24.56 msec2, and low/high frequency from 1.45 to 6.33 msec2. [Conclusion] Standing after cold stimulation affected autonomic variables, but did not affect the heart rate or blood pressure, possibly because of damaged peripheral blood vessels. Further research is required to demonstrate the effect of cold stimulation on orthostatic hypotension.

Evidence of an association between cardiac-locomotor synchronization and lower leg muscle blood perfusion during walking.

[Purpose] The purpose of this study was to investigate whether the occurrence of cardiac-locomotor synchronization (CLS) improves lower leg muscle blood perfusion during walking. [Subjects and Methods] Eleven healthy men were studied while performing two treadmill protocols. The CLS protocol involved subjects walking at the frequency of their heart rate (HR) to induce CLS. The free protocol (reference) involved subjects walking at a self-selected cadence. The treadmill load was identical in the two protocols. Electrocardiographic signals for HR, foot switch signals for step rate and near-infrared spectroscopy (NIRS) signals for total haemoglobin (total Hb) in the lower leg muscles were measured continuously for 10 min after HR reached a steady state. [Results] The mean HR and mean step rate did not differ between the CLS and free protocols. However, total Hb was significantly higher in the CLS protocol than in the free protocol. The rate of increase in total Hb positively correlated with the strength of CLS. [Conclusion] These results suggest that the occurrence of CLS enhances lower leg muscle blood perfusion by increasing the strength of CLS during walking.

Effects of Synchronization between Cardiac and Locomotor Rhythms on Oxygen Pulse during Walking.

The oObjective of the study was to investigate whether the occurrence of cardiac-locomotor synchronization (CLS) affects oxygen pulse (O2 pulse, mL/beat) during walking. Twelve healthy men were studied under two treadmill protocols. The CLS protocol involved subjects walking at a frequency of their heart rate (HR) to induce CLS. The free protocol (reference) involved subjects walking at a self-selected cadence. The treadmill load was equal between the two protocols and was adjusted so that the subject's HR was maintained at approximately 120 bpm. Electrocardiographic signals, foot switch signals, and oxygen consumption (VO2) were measured continuously for 10 min after the heart rate reached a steady state. VO2, O2 pulse, and mean HR were calculated. VO2 and O2 pulse were significantly higher in subjects in the CLS protocol compared to those in the free protocol. However, mean HR was not different between the two groups. The synchronization strength was significantly related to the increase in O2 pulse in subjects in the CLS protocol compared with those in the free protocol. These results suggest that the occurrence of CLS enhances O2 pulse by increasing the strength of CLS during walking. Key PointsTwelve healthy men walked at a frequency of their heart rate (CLS protocol) and at a self-selected cadence (free protocol).Walking at the frequency of heart rate would induce the CLS by entrainment.Oxygen pulse was significantly higher in subjects in the CLS protocol compared to those in the free protocol.The occurrence of CLS enhances oxygen pulse by increasing the strength of CLS during walking.

Autonomic responses to aerobic and resistance exercise in patients with chronic musculoskeletal pain: A systematic review.

BACKGROUND: It is unknown whether patients with chronic musculoskeletal pain (CMP) show autonomic dysregulation after exercise, and the interventional effects of exercise on the autonomic dysregulation have not been elucidated. The objectives of this study were to reveal acute autonomic responses after aerobic and resistance exercises and the interventional effects of both exercises on autonomic dysregulation in patients with CMP. METHODS: A systematic search using nine electronic databases was performed based on three key search terms: "chronic musculoskeletal pain," "autonomic nervous system," and "exercise." Data were extracted from measurements of the autonomic nervous system and pain. RESULTS: We found a total of 1170 articles; 17 were finally included, incorporating 12 observational and five interventional studies. Although a comparator has not been specified, healthy controls were compared to patients with CMP in observational studies. Three of five interventional studies were pre-post study with healthy controls as a comparator or no controls. The other two interventional studies were randomized controlled trial with a different treatment e.g., stretching. There were four good, 10 fair, and three poor-quality articles. The total number of participants was 617, of which 551 were female. There was high heterogeneity among the five disease conditions and nine outcome measures. Following one-time exposure to aerobic and resistance exercises, abnormal autonomic responses (sympathetic activation and parasympathetic withdrawal), which were absent in healthy controls, were observed in patients with CMP. The effects of aerobic and resistance exercise as long-term interventions were unclear since we identified both positive effects and no change in the autonomic activities in patients with CMP. CONCLUSIONS: This study indicates dysfunctional autonomic responses following one-time exposure to exercise and inconsistent interventional effects in the autonomic activities in patients with CMP. Appropriate therapeutic dose is necessary for studying the management of autonomic regulation and pain after exercise.