The effects of pain induced by blood flow occlusion in one leg on exercise tolerance and corticospinal excitability and inhibition of the contralateral leg in males.

Experiencing pain in one leg can alter exercise tolerance and neuromuscular fatigue (NMF) responses in the contralateral leg; however, the corticospinal modulations to nonlocal experimental pain induced by blood flow occlusion remain unknown. In three randomized visits, 13 male participants performed 25% of isometric maximal voluntary contraction (25%IMVC) to task failure with one leg preceded by (i) 6-min rest (CON), (ii) cycling at 80% of peak power output until task failure with the contralateral leg (CYCL), or (iii) CYCL followed by blood flow occlusion (OCCL) during 25%IMVC. NMF assessments (IMVC, voluntary activation [VA], and potentiated twitch [Qtw]) were performed at baseline and task failure. During the 25%IMVC, transcranial magnetic stimulations were performed to obtain motor-evoked potential (MEP), silent period (SP), and short intracortical inhibition (SICI). 25%IMVC was the shortest in OCCL (105 ± 50s) and shorter in CYCL (154 ± 68 s) than CON (219 ± 105 s) (p < 0.05). IMVC declined less after OCCL (-24 ± 19%) and CYCL (-27 ± 18%), then CON (-35 ± 11%) (p < 0.05). Qtw declined less in OCCL (-40 ± 25%) compared to CYCL (-50 ± 22%) and CON (-50 ± 21%) (p < 0.05). VA was similar amongst conditions. MEP and SP increased and SICI decreased throughout the task, while SP was longer for OCCL compared to CYC condition (p < 0.05). The results suggest that pain in one leg diminishes contralateral limb exercise tolerance and NMF development and modulate corticospinal inhibition in males. Novelty: Pain in one leg diminished MVC and twitch force decline in the contralateral limb. Experimental pain induced by blood flow occlusion may modulation corticospinal inhibition of the neural circuitries innervating the contralateral exercise limb.

Post-exertional Malaise in People With Chronic Cancer-Related Fatigue.

CONTEXT: Cancer-related fatigue (CRF) is a distressing and persistent sense of tiredness or exhaustion that interferes with usual functioning. Chronic CRF continues for months after curative cancer treatment is complete. Post-exertional malaise (PEM) is a worsening of symptoms after physical or mental activity, with limited investigations in people with chronic CRF. OBJECTIVES: The purpose of this study was to identify and describe self-reported incidences of PEM in people with chronic CRF. METHODS: Participants (n = 18) were eligible if they scored ≤34 on the Functional Assessment of Chronic Illness Therapy-Fatigue scale and had a cancer-related onset of fatigue. Participants completed a brief questionnaire to assess PEM during a six-month time frame (the DePaul Symptom Questionnaire-PEM). In addition, a maximal exercise test was used to investigate self-reported symptom exacerbation (via an open-ended questionnaire) after strenuous physical exertion. RESULTS: On the DePaul Symptom Questionnaire-PEM, three participants met previously defined scoring criteria, which included experiencing moderate to very severe symptoms at least half of the time, worsening of fatigue after minimal effort, plus a recovery duration of >24 hours. Content analysis of responses to open-ended questionnaires identified five people who experienced a delayed recovery and symptoms of PEM after maximal exercise. CONCLUSION: A subset of people with chronic CRF (up to 33% in this sample) may experience PEM. Exercise specialists and health care professionals working with people with chronic CRF must be aware that PEM may be an issue. Symptom exacerbation after exercise should be monitored, and exercise should be tailored and adapted to limit the potential for harm.