Operating lung volumes are affected by exercise mode but not trunk and hip angle during maximal exercise

Introduction

Despite VO_2peak being, generally, greater while running compared to cycling, ventilation (V _E) during maximal exercise is less while running compared to cycling. Differences in operating lung volumes (OLV) between maximal running and cycling could be one explanation for previously observed differences in V _E and this could be due to differences in body position e.g., trunk/hip angle during exercise.

Purpose

We asked whether OLV differed between maximal running and cycling and if this difference was due to trunk/hip angle during exercise.

Methods

Eighteen men performed three graded maximal exercise tests; one while running, one while cycling in the drop position (i.e., extreme hip flexion), and one while cycling upright (i.e., seated with thorax upright). Resting flow-volume characteristics were measured in each body position to be used during exercise. Tidal flow-volume loops were measured throughout the exercise.

Results

V _E during maximal running (148.8 ± 18.9 L min^?1) tended to be lower than during cycling in the drop position (158.5 ± 24.7 L min^?1; p = 0.07) and in the upright position (158.5 ± 23.7 L min^?1; p = 0.06). End-inspiratory and end-expiratory lung volumes (EILV, EELV) were significantly larger during drop cycling compared to running (87.1 ± 4.1 and 35.8 ± 6.2 vs. 83.9 ± 6.0 and 33.0 ± 5.7 % FVC), but only EILV was larger during upright cycling compared to running (88.2 ± 3.5 % FVC). OLV and V _E did not differ between cycling positions.

Conclusion

Since OLV are altered by exercise mode, but cycling position did not have a significant impact on OLV, we conclude that trunk/hip angle is likely not the primary factor determining OLV during maximal exercise.