Respiratory muscle training and maximum aerobic power in hypoxia

Respiratory muscle training positively affects vasomotor response in young healthy women

Vasomotor response is related to the capacity of the vessel to maintain vascular tone within a narrow range. Two main control mechanisms are involved: the autonomic control of the sympathetic neural drive (global control) and the endothelial smooth cells capacity to respond to mechanical stress by releasing vasoactive factors (peripheral control). The aim of this study was to evaluate the effects of respiratory muscle training (RMT) on vasomotor response, assessed by flow-mediated dilation (FMD) and heart rate variability, in young healthy females. The hypothesis was that RMT could enhance the balance between sympathetic and parasympathetic neural drive and reduce vessel shear stress. Thus, twenty-four women were randomly assigned to either RMT or SHAM group. Maximal inspiratory mouth pressure and maximum voluntary ventilation were utilized to assess the effectiveness of the RMT program, which consisted of three sessions of isocapnic hyperventilation/ week for eight weeks, (twenty-four training sessions). Heart rate variability assessed autonomic balance, a global factor regulating the vasomotor response. Endothelial function was determined by measuring brachial artery vasodilation normalized by shear rate (%FMD/SR). After RMT, but not SHAM, maximal inspiratory mouth pressure and maximum voluntary ventilation increased significantly (+31% and +16%, respectively). Changes in heart rate variability were negligible in both groups. Only RMT exhibited a significant increase in %FMD/SR (+45%; p<0.05). These data suggest a positive effect of RMT on vasomotor response that may be due to a reduction in arterial shear stress, and not through modulation of sympatho-vagal balance.

An exploratory study of respiratory muscle endurance training in high lesion level paraplegic handbike athletes

OBJECTIVE

To investigate the impact of respiratory muscle endurance training (RMET) on lung function and exercise performance in athletes with high lesion level paraplegia.

DESIGN

This was a case-control intervention study.

SETTING

Sport and exercise science laboratories and bike path.

PARTICIPANTS

Twelve competitive handbike athletes with high lesion level paraplegia matched by lesion and fitness level in training (T) group (7) and control (C) group (5).

INTERVENTIONS

The T group performed 20 RMET training sessions over a 4-week period using a SpiroTiger. Each session lasted for 30 minutes. The C group did not perform any RMET.

MAIN OUTCOME MEASURES

Resting lung function, respiratory muscle endurance, and exercise performance (arm cranking maximal incremental test and simulated handbike time trial).

RESULTS

Resting lung function was not different between groups and did not change with the intervention. After RMET, the respiratory muscle endurance was significantly increased by 27% in the T group but did not alter in the C group. Final minute ventilation was increased from 89 ± 20 L/min to 112 ± 20 L/min after RMET in the T group and the sensation of dyspnea decreased (P < 0.05). Peak oxygen consumption, peak mechanical power output, and handbike time trial performance were not different between groups and did not change with the RMET intervention.

CONCLUSIONS

A short-term RMET intervention in handbike athletes with high lesion level paraplegia improved respiratory muscle endurance but had little impact on overall exercise performance.