The role of sense of effort on self-selected cycling power output

Abstract

Purpose: We explored the effects of the sense of effort and accompanying perceptions of peripheral discomfort on self-selected cycle power output under two different inspired O2 fractions.Methods: On separate days, eight trained males cycled for 5 min at a constant subjective effort (sense of effort of ‘3’ on a modified Borg CR10 scale), immediately followed by five 4-s progressive submaximal (sense of effort of “4, 5, 6, 7, and 8”; 40 s between bouts) and two 4-s maximal (sense of effort of “10”; 3 min between bouts) bouts under normoxia (NM: fraction of inspired O2 [FiO2] 0.21) and hypoxia (HY: [FiO2] 0.13). Physiological (Heart Rate, arterial oxygen saturation (SpO2) and quadriceps Root Mean Square (RMS) electromyographical activity) and perceptual responses (overall peripheral discomfort, difficulty breathing and limb discomfort) were recorded.Results: Power output and normalized quadriceps RMS activity were not different between conditions during any exercise bout (p > 0.05) and remained unchanged across time during the constant-effort cycling. SpO2 was lower, while heart rate and ratings of perceived difficulty breathing were higher under HY, compared to NM, at all time points (p < 0.05). During the constant-effort cycling, heart rate, overall perceived discomfort, difficulty breathing and limb discomfort increased with time (all p < 0.05). All variables (except SpO2) increased along with sense of effort during the brief progressive cycling bouts (all p < 0.05). During the two maximal cycling bouts, ratings of overall peripheral discomfort displayed an interaction between time and condition with ratings higher in the second bout under HY vs. NM conditions. Conclusion: During self-selected, constant-effort and brief progressive, sub-maximal, and maximal cycling bouts, mechanical work is regulated in parallel to the sense of effort, independently from peripheral sensations of discomfort.

Towards a three-dimensional framework of centrally regulated and goal-directed exercise behaviour: a narrative review

“…The authors used modified CR-10 scales and ‘clamped’ the sense of effort at ‘3’ during a 5 min submaximal ride, followed by five progressive sprints, and two maximal sprints clamped at an effort of ‘10’. Mental sense of effort was closely related to alterations in power output and quadriceps muscle activation, while localised and overall discomfort ratings increased in parallel with physiological disturbances during constant-effort cycling and difficulty breathing was significantly elevated during the hypoxia trial 65. This suggests that (A) perceived mental strain and perceived physical strain can be experimentally dissociated, (B) perceived mental strain accurately reflects power output during short-term sprints and (C) perceived physical strain accurately reflects disruption of the physiological state.…”

“…To the best of our knowledge, only one other study has investigated the role of sense of effort and physiological discomfort on self-selected power output in cyclists during normoxia and hypoxia trials 65. The authors used modified CR-10 scales and ‘clamped’ the sense of effort at ‘3’ during a 5 min submaximal ride, followed by five progressive sprints, and two maximal sprints clamped at an effort of ‘10’.…”

The interactive effect of cooling and hypoxia on forearm fatigue development

“…RPE reflected the temporal decline in overall fatigue, showing a trend for decrease early in hypoxia (MVC 1 ) and a small effect on effort during the latter stages of the protocol with cooling (MVC 3 & MVC 4 ). Since participants received no specific detailing on the interpretation of RPE, the increase is likely in response to both a greater mental effort (Marcora & Staiano, 2010) and a higher peripheral discomfort (Christian et al 2014b) with fatigue.…”

“…In hypoxia, evidence also suggests increased afferent feedback and decreased cerebral oxygenation can reduce voluntary drive to the muscle, exacerbating net fatigue Amann et al 2006a;2007b;Goodall et al 2010;Millet, 2008;. However, the relative contributions of afferent feedback and cerebral oxygenation, as well as the sense of effort, to changes in central drive during 4 fatiguing exercise in hypoxia remains subject to on-going investigations (Millet et al 2008;Goodall et al 2010;Amann et al, 2013;Christian et al 2014a;Christian et al 2014b). …”

An Investigation of Fatigue in Stationary Biking with Application to Iliotibial Band Syndrome Development

“…Following confirmation of data acquisition system arming, the systems were triggered and the volunteer was guided through the following cycling endurance routine, in which resistance levels are self-selected and are guided by perceived sense of effort [ Figure 2- replicating a more realistic training simulation, the use of a constant "sense of effort" routine for cycling decoupled mechanical power output from the perceived discomfort of cycling (Christian et al 2014). Therefore, mechanical power output during the short duration ride was maximized, and fatigue onset was accelerated (relative to a self-selected constant "perceived difficulty" routine).…”