5. DISCUSSION
5.1 Testing Conditions
5.1.3 Evidence of Internal Regulatory Mechanism
Traditionally, during exercise, HR and RPE increase linearly (Borg, 1982; 1990;
Noakes, 2004; Swart et al., 2012) and this occurs above the exercising individual’s steady state (McArdle et al., 2007). However, in cases during the current research where no significant increases were found in HR responses during the constant HR condition, the RPE showed significant (P<0.05) increases over time (see Table VIII).
Correspondingly, workload during the constant HR, workload, and RPE condition
demonstrated no changes over time. This evidence shows that participants are able to maintain their physiological and performance responses at a constant rate;
however, their perceptual response (RPE) increased over time in all three-test conditions.
Therefore, the participants’ perception of fatigue came prior to the physiological and performance decrements concerning the expression of fatigue. This is because there was significant change in HR, as the participants were not exercising above their steady state (McArdle et al., 2007). If the participants were exercising above the HR steady state, performance decrements would have been observed, but this was not the case especially during the constant HR condition, when significant (p<0.05) changes in RPE were observed (see Figure 12 and Table VIII). This is further evidence for an internal regulatory mechanism as proposed by Noakes and colleagues (Noakes et al., 2004; St Clair Gibson et al., 2003; Lambert et al., 2005;
Noakes, 2012; Swart et al., 2012) who state that fatigue is perceived prior to any significant physiological responses when performance decrements are observed (Noakes, 2012). The regulatory mechanism works to maintain homeostasis and protect the exercising individual from catastrophic events (Noakes, 2012). Exercise activities conducted above the steady state result in premature fatigue onset relative to exercise conducted at a steady stated such as the conditions in the constant HR condition. Hence, there was no observable significant drop in the workload during the constant HR condition because the participants were not exercising above their steady state and therefore could maintain a constant workload for the duration of the exercise.
While workload remained constant and RPE increased during the constant HR condition, this illustrated the fact that participants were working at their steady state, as there was no observable change in HR or a decrease in workload (Borg, 1990:
Noakes et al., 2001; Tucker et al., 2004). Participants kept both HR and workload constant while RPE increased before any significant changes in HR and workload.
The significant change in RPE was an indication of fatigue, which preceded the expression of fatigue in physiological and performance response. These findings confirm the existence of a regulatory mechanism that works to protect the exercising individual from over-exertion and possible catastrophic events during exercise.
that both HR and RPE increased over time. Therefore, the findings from the constant HR condition do not apply in the constant workload conditions, as the association between these two variables has been re-established.
Interestingly, under the constant RPE condition where RPE was expected to remain constant, participants could not maintain RPE within the prescribed range.
Therefore, even though participants were instructed to consciously control their RPE response, this was not achieved as there was significant (p<0.05) found in the RPE response during the consistency testing (see Figure 17 and Table XVI). The significant changes (p<0.05) observed in the RPE response during the constant RPE condition differed from the RPE response recorded during both the constant HR and workload conditions. This may be the fact that participants were consciously trying to override the internal regulatory mechanism, which seems to operate at the subconscious level (Kay et al., 2001; Noakes et al., 2004; Noakes & St Clair Gibson, 2004; Noakes et al., 2005). The notion that the proposed internal regulator operates at a subconscious level is supported by the fact that the participants conscious effort did not translate into constant RPE response during the constant RPE condition (St Clair Gibson & Noakes, 2004). It is evident that the participants were not able to regulating the exercise performance using exertion levels / RPE as in all three test conditions RPE increased significantly (p<0.05) over time and could not be maintained within a prescribed range, even under the constant RPE condition.
However, it was possible to keep both workload and HR constant when the participants were requested to maintain a constant HR or workload during the given test condition.
Therefore, during exercise participants optimised workload as it can be seen by the constant workload in both the constant RPE and constant HR condition, where workload showed no significant changes even though it was a dependent variable.
Alternatively, participants exercise with a load, which their physiological system can manage until exhaustion, in order to preserve energy through being efficient in energy expenditure as a form of pacing (Lambert et al., 2005; Ament & Verkerke, 2009; Enoka & Duchateau, 2008; Theurel & Lepers, 2008; Shei & Micklebrough, 2013). This inclination to preserve energy may be linked to the nature of humans to instinctively aim to preserve energy during physical activities (McArdle et al., 2007).
Therefore, rather than regulating RPE, humans regulate components that will aid in
energy preservation such as performance and physiological systems (Noakes, 2000;
Noakes, 2004; McArdle et al., 2007; Noakes, 2012). Support for the notion that the participants were regulating energy expenditure during the constant RPE condition comes from the fact that participants regulated workload instead of RPE. The suggestion about energy regulation is possible because HR may be used as an indicator of energy expenditure (McArdle et al., 2007; Sundberg et al., 2016).