The Influence of Exercise Intensity on Exercise Induced Diaphragm Fatigue in Female Subjects

Exercise induced arterial hypoxemia (EIAH), expiratory flow limitation (EFL) and exercise induced diaphragm fatigue (EIDF) are examples of how the pulmonary system limits endurance exercise. The differences in the female anatomy and hormone fluctuations have been reported to cause differences in the occurrence of EIAH and EFL in males and females. EIDF has been reported to occur in males, but to date no investigations have reported the occurrence of EIDF in females. Therefore the purpose of this study was to determine the occurrence of exercise induced diaphragm fatigue (EIDF) in females identified by significant reductions in transdiaphramatic pressure (Pdi) post exercise in response to supramaximal bilateral phrenic nerve stimulation. Ten females 20 (± 0.37) years old completed exercise at 75 and 95% V02max to volitional fatigue on 2 separate days, on approximately day 7 (± 2 days) of their menstrual cycle. Bilateral phrenic nerve stimulation in combination with balloon tipped catheters, used to measure esophageal and gastric pressure, were used to provide an objective measurement of trans-diaphragmatic pressure. BPNS was performed at 1,10,20,50, and 100 Hz prior to exercise, immediately after exercise, 30, and 60 minutes after exercise. Post exercise there were no significant reductions in Pdi after the 75% V02max exercise condition; however, in the 95% V02max exercise condition Pdi was significantly reduced with 1 and 50 Hz stimulation. Recovery from fatigue occurred within approximately 30 minutes after exercise. This study objectively reported the occurrence of EIDF in females exercising at 95% V02max

Perturbation training to promote safe independent mobility post-stroke: study protocol for a randomized controlled trial

Abstract Background Falls are one of the most common medical complications post-stroke. Physical exercise, particularly exercise that challenges balance, reduces the risk of falls among healthy and frail older adults. However, exercise has not proven effective for preventing falls post-stroke. Falls ultimately occur when an individual fails to recover from a loss of balance. Thus, training to specifically improve reactive balance control could prevent falls. Perturbation training aims to improve reactive balance control by repeatedly exposing participants to postural perturbations. There is emerging evidence that perturbation training reduces fall rates among individuals with neurological conditions, such as Parkinson disease. The primary aim of this work is to determine if perturbation-based balance training can reduce occurrence of falls in daily life among individuals with chronic stroke. Secondary objectives are to determine the effect of perturbation training on balance confidence and activity restriction, and functional balance and mobility. Methods/design Individuals with chronic stroke will be recruited. Participants will be randomly assigned to one of two groups: 1) perturbation training, or 2) ‘traditional’ balance training. Perturbation training will involve both manual perturbations (e.g., a push or pull from a physiotherapist), and rapid voluntary movements to cause a loss of balance. Training will occur twice per week for 6 weeks. Participants will record falls and activity for 12 months following completion of the training program. Standardized clinical tools will be used to assess functional balance and mobility, and balance confidence before and after training. Discussion Falls are a significant problem for those with stroke. Despite the large body of work demonstrating effective interventions, such as exercise, for preventing falls in other populations, there is little evidence for interventions that prevent falls post-stroke. The proposed study will investigate a novel and promising intervention: perturbation training. If effective, this training has the potential to not only prevent falls, but to also improve safe independent mobility and engagement in daily activities for those with stroke. Trial registration Current Controlled Trials: ISRCTN05434601