Abstract

Introduction
Compared to other cardiorespiratory parameters, respiratory frequency (fR) is suggested as one of the most important contributors to self-paced endurance performance. This is based on the strong relationship fR shares with RPE, irrespective of event duration (Nicolò et al., 2016). However, it is yet to be established if fR and RPE interaction differs during multi-modal events (i.e. triathlon). Indeed, the complexity of such exercise may well alter the relationships that are typically seen between perceptual and physiological status during single-mode events (Taylor & Smith, 2013). Furthermore, it is suggested that affective status may be more important than RPE to the pacing of endurance performance. This study therefore examined the associations between cardiorespiratory responses, RPE and affect during isolated and triathlon-specific cycling performance.
Methods
Eleven non-elite male triathletes (mean ± SD: age 36.9 ± 8.4 yrs, VO2max 4.1 ± 0.3 L·min-1, Wmax 344 ± 21 W) completed two laboratory-based trials 9 ± 4 days apart, each incorporating a 500 kJ (~20 km) cycling time-trial (CTT) performed on an SRM ergometer. The first CTT was completed in isolation, whilst the second CTT formed part of a simulated sprint-distance triathlon (0.75 km flume swim, 500 kJ bike, 5 km treadmill run). Cardiorespiratory (fR, VE, VO2, VT, HR) and perceptual (RPE and affect) responses were obtained every 100 kJ. Relationships between these measures were examined by calculation of within-subject correlation coefficients.
Results
During isolated CTT’s, RPE was significantly related (P < 0.05) with fR (r = 0.80), VE (r = 0.58), VO2 (r = 0.57), VT (r = 0.49) and HR (r = 0.79), whilst affect was significantly related (P < 0.05) with fR (r = 0.70), VE (r = 0.37), VT (r = 0.63) and HR (r = 0.67) but not VO2 (r = 0.26). During triathlon-specific CTT’s, RPE was significantly related (P < 0.05) with fR (r = 0.51), VO2 (r = 0.30), VT (r = 0.43) and HR (r = 0.51) but not VE (r = 0.03), whilst affect was significantly related (P < 0.05) with fR (r = 0.47), VT (r = 0.60) and HR (r = 0.43) but not VO2 (r = 0.09) or VE (r = 0.08).
Discussion
In accordance with Nicolò et al. (2016) fR demonstrated the strongest relationship with RPE across both CTT’s, relative to other cardiorespiratory measures. This trend was also apparent for the relationships between cardiorespiratory responses and affect, though the strength of these was generally lower compared to those seen with RPE. Associations between perceptual and cardiorespiratory responses were also consistently weaker during triathlon-specific CTT. These findings support the view that fR and RPE interaction may be one of the most important contributors to pacing during single and multi-modal events, whilst also illustrating unique relationships between perceptual and physiological responses during triathlon cycling.