Abstract
Recumbent and supine cycling are common exercise modes in rehabilitation and clinical settings but the influence of postures on work efficiency is unclear. Therefore, the aim of this study was to compare metabolic and ventilatory efficiency during upright, recumbent, and supine postures. Potential differences should be assessed for suitable diagnostics and for prescriptions of training that probably is performed in alternative postures. Eighteen healthy subjects (age: 47.2 ± 18.4 years; 10 female, 8 male) participated in the study and each completed three incremental cycle ergometer tests until exhaustion in upright, recumbent (40°), and supine positions. Gas exchange, heart rate (HR), and lactate concentrations were analyzed and efficiency was calculated subsequently. Testing sessions were performed in random order within a 2-week period. Upright cycling resulted in significantly higher peak values [power output, oxygen uptake (Vo2), HR] as well as performance at lactate and ventilatory thresholds in comparison to recumbent or supine positions. Vco2/Vo2 slope and ventilatory efficiency (VE/Vco2 slope) were not affected by posture. Aerobic work efficiency (Vo2/P slope) and gross efficiency (GE) differed significantly between postures. Hereby, GE was lowest in supine cycling, particularly obvious in a mainly aerobic condition at 70 Watt [Median 11.6 (IQR 10.9–13.3) vs. recumbent: 15.9 (IQR 15.6–18.3) and upright: 17.4 (IQR 15.1–18.3)]. Peak power as well as GE and work efficiency values are influenced by cycling position, reinforcing the importance of adjusting test results for training prescriptions. Surprisingly, ventilatory efficiency was not affected in this study and therefore does not seem to falsify test results for pulmonary diagnostics.
Highlights
Cycling is one of the most common method to assess and promote cardiorespiratory fitness in recreational sports, as well as in rehabilitation and clinical practice (Garber et al, 2011; American College of Sports Medicine et al, 2018)
Cycling in an upright position resulted in significantly greater Pmax and higher VO2peak values in comparison with a recumbent and supine position (P < 0.001)
The present study demonstrates for the first time the effect of posture on cycling efficiency in supine or upright cycling position, and in a clinically relevant recumbent position during graded exercise testing
Summary
Cycling is one of the most common method to assess and promote cardiorespiratory fitness in recreational sports, as well as in rehabilitation and clinical practice (Garber et al, 2011; American College of Sports Medicine et al, 2018). Cardiopulmonary exercise tests (CPET) play a major role in assessing physical capacity and obtaining useful clinical diagnosis and prognostic information (Guazzi et al, 2012, 2016; Arena et al, 2020) in patients with cardiovascular and pulmonary diseases. Cardiopulmonary exercise test results are used to prescribe adequate training intensities. Efficiency in Three Different Cycling-Postures for appropriate training stimuli (Pedersen and Saltin, 2015) or evaluating the effectiveness of exercise interventions, especially in research settings. The limited transferability from one position to another (Ray and Cureton, 1991; Bonzheim et al, 1992) must be considered using CPET results as a basis for clinical or performance diagnostics. To provide adequate training recommendations, cycling position must be taken into account, especially if training and testing postures on the ergometer are different
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