An individuals’ prediction of the level of perceived exertion that they expect to experience in a future bout of exercise (i.e., predicted RPE) may help to explain their motivation to perform that exercise. Predicted RPE can be defined as a global estimate of the average RPE that is expected for an entire bout of upcoming exercise or PA. It is rated prior to performance of that activity. Poulton and colleagues (2002) studied predicted physical discomfort. Although the investigation did not measure predicted RPE directly, the definition of perceived exertion includes the construct of physical discomfort. Significant relations were found between patterns of the overprediction of physical discomfort and negative self-reported health status, negative attitudes about exercise, high body mass index, and poor CRF. In addition, the greater the mismatch between predicted and actual physical discomfort, the lower the physical activity level (Poulton et al. 2002). Therefore, measuring predicted RPE prior to a bout of exercise may help determine whether an individual is at risk of low adherence to an exercise program, identified by the overprediction (i.e., higher value) of the expected RPE.

It is of interest to determine whether predicted RPE matches momentary RPE for a given type of exercise programming. A significant difference between predicted RPE and the mean of momentary RPE’s for a single exercise session indicates a perceptual mismatch potentially leading to negative attitudes regarding adoption and maintenance of PA participation. Few investigations have studied predicted RPE. Young adult men and women overpredicted RPE prior to load-incremented cycle ergometer exercise (Haile et al. 2008; Hunt et al. 2007). However, the relation of this mismatch with attitudes towards exercise, PA level or adherence to exercise was not investigated. In addition, a load-incremented exercise test is not a common exercise format that is included in steady state or interval prescriptions for health-related fitness. Kane and colleagues (2010) compared predicted RPE and momentary RPE in response to a shuttle run test called the Progressive Aerobic Cardiovascular Endurance Run (PACER). The subjects for the investigation were children who reported moderate experience with aerobic exercise. Predicted RPE exhibited a match with momentary RPE, which may have been a result of previous experience with similar aerobic activities resulting in an accurate expectation of the exertion to be experienced (Kane et al. 2010). Future research is necessary to determine if predicted RPE can be used to identify barriers to exercise adherence. This can be done by calculating the difference between predicted RPE and the mean of the sequentially determined momentary RPE of exercise bouts normally prescribed to improve CRF.

An individual’s memory of the perceptual experience of a previously performed bout of exercise may affect the accurate reporting of the specific exercise intensity performed during that bout. It may also affect an individual’s desire to perform similar exercise in the future. Session RPE can be defined as a post-exercise estimate of the global RPE for an entire bout of exercise or PA. It is rated following completion of that activity. Session RPE has been measured following a wide variety of exercise and sport modalities, including cycling (Foster et al. 1996, 2001; Green et al. 2007; Haile et al. 2008, 2013b; Herman et al. 2006; Hunt et al. 2007; Killen et al. 2013; Kilpatrick et al. 2009; Rodriguex-Marroyo et al. 2012), walking/running (Davis et al. 2012; Foster et al. 1996; Green et al. 2009; Haile et al. 2013a; Minganti et al. 2011b; Seiler and Kjerland 2006), swimming (Wallace et al. 2009), diving (Minganti et al. 2011a), soccer (Alexiou and Coutts 2008; Algroy et al. 2011; Gomez-Piriz et al. 2011; Impellizzeri et al. 2004; Tessitore et al. 2011), basketball (Foster et al. 2001; Moreira et al. 2012), speed-skating (Foster et al. 1996), rugby (McLean et al. 2010), judo (Viveiros et al. 2011), taekwondo (Haddad et al. 2011), futsal (Milanez et al. 2011), teamgym (Minganti et al. 2010), sprint kayaking (Borges et al. 2014), field-based speed training (Lockie et al. 2011), and resistance exercise (Bacon et al. 2012; Charro et al. 2010; Day et al. 2004; Egan 2003; Egan et al. 2006; McGuigan et al. 2004, 2008; Pritchett et al. 2009; Singh et al. 2007; Sweet et al. 2004). In most of these investigations, session RPE was rated between 5 and 30 min following the exercise bout.

Session RPE was originally developed to track overtraining in endurance athletes (Foster et al. 2001), but was recently proposed as a method to track the relative exercise intensity for individuals participating in PA intervention programs (Haile et al. 2013b). Whether an individual is previously sedentary and attempting to adopt a new exercise program or an elite athlete, session RPE can be a practical, affordable and non-invasive method to describe the relative intensity of physical activity and exercise performed within training or a general conditioning program. In addition, it may be useful for predicting injury or illness as a result of overtraining and the failure to achieve physiological benefits as a result of undertraining (Foster et al. 2001; Haile et al. 2013b).

Session RPE has been widely studied, especially in comparison to predicted RPE. However, few studies have investigated the validity of session RPE as a global value that accurately represents the mean of momentary RPE responses measured during exercise. It is known that session RPE generally changes in correspondence with variations in physiological variables measured during exercise, including HR, VO₂ and blood lactate concentrations (Herman et al. 2006; Rodriguex-Marroyo et al. 2012; Seiler and Kjerland 2006). In previous investigations, session RPE has exhibited an acceptable degree of concurrent validity because it changes in a predictable direction with well-known physiological exertional mediators. However, by definition, session RPE is the global estimate of the average of the sequentially estimated momentary RPE determined during a previous exercise bout. To exhibit construct validity, session RPE should be equal to the mean of momentary RPE responses. Such validity is achieved when scale anchoring procedures as presented during RPE scale orientation are understood by the individual and conform to Borg’s Range Model. Given these measurement procedures, session RPE can be used to estimate the relative exercise intensity. Therefore, session RPE that is equal to the mean of the momentary RPE could be used to predict the physiological responses that describe the relative intensity of a previously performed exercise session. This information would be appropriate for use in PA logs as part of a behavioral intervention involving systematic exercise participation. However, if session RPE exhibits a mismatch compared with the mean of the momentary RPE, then the measure likely does not accurately represent the global exertion responses for the entire exercise session. In such an instance, the session RPE response may not be a useful index of the global exertional experience and as such the relative exercise intensity for the entire preceding exercise bout.

Green and colleagues (2009) measured session RPE 20 min following treadmill exercise bouts at 70 % of VO₂max. Whether the exercise was performed for 20, 30 or 40 min in separate bouts, session RPE was significantly greater than the mean of the momentary RPE. Kilpatrick and colleagues (2009) measured session RPE 15 min following 30 min of treadmill exercise. Subjects performed three separate bouts at an intensity of their choosing based on verbal instructions to attain light, moderate, or vigorous intensity. For all three bouts session RPE was significantly greater than mean momentary RPE. Haile and colleagues (2013b) measured session RPE 15 min following two separate 20 min bouts of cycle ergometer exercise. In the first bout, subjects performed self-selected exercise intensity based on what they felt was a “good workout.” In the second bout, each subject’s own previously determined self-selected intensity was then prescribed (i.e., imposed) on that subject. However, the subject was told the brake resistance was “selected by the investigators.” In either case, whether the same intensity was self-selected or imposed, session RPE was significantly greater than the mean of the momentary RPE (Haile et al. 2013b). In all three studies, session RPE was not representative of the mean momentary RPE. However, session RPE was similar to momentary RPE estimated near the end of exercise. Therefore, it seems that the most recently experienced momentary RPE values may dominate the session RPE response. In some individuals, there may be a certain amount of perceptual memory fade in the minutes following exercise cessation. This time dependent decay may not allow the momentary RPE experienced near the beginning of exercise to contribute to the global response. It may be beneficial to ask subjects to rate session RPE sooner following exercise than the 15–20-min period that has been commonly used in many investigations.

Another factor that has been shown to mediate the session RPE response is the effect of changes in exercise intensity during a single performance. This effect may be a potential reason why the session RPE has been rated consistently higher than the mean of the momentary RPE. Green and colleagues (2007) found that session RPE was higher following interval exercise in comparison to constant load cycle exercise when overall workload was the same between test protocols. In this experimental design, average workload was the same between interval and constant load exercise trials. However, the intensity of each exercise interval was higher than that at any time point in the constant load protocol, likely resulting in a greater session RPE for the interval protocol. Such a difference was expected because of the greater disruption in metabolic homeostasis experienced during interval exercise relative to constant workload exercise, regardless that average workload was the same (Green et al. 2007). In addition, two other investigations found that subjects rated session RPE greater than the mean momentary RPE following load-incremented cycle ergometer exercise (Haile et al. 2008; Hunt et al. 2007). This response was most likely influenced by the high exercise intensities performed closer to the end of the exercise session. However, these studies did not compare session RPE with momentary RPE values. In the study by Haile and colleagues (2013b), subjects were allowed to self-select exercise intensity every 5 min during a 20-min cycle ergometer exercise trial. On average, subjects increased intensity and momentary RPE values throughout the trial. Subsequently, session RPE was greater than the mean momentary RPE. However, the session RPE value was similar to the momentary RPE values rated near the end of exercise, where the highest momentary RPE values occurred (Haile et al. 2013b).

Based on this previous research, it is possible that the time segments of a previous exercise bout can differentially dominate the global session RPE response. Higher exertional perceptions that are linked to comparatively higher exercise intensity, either performed during interval exercise or near the end of load-incremented and self-selected exercise, may result in a higher session RPE response (Green et al. 2007; Haile et al. 2008, 2013b; Hunt et al. 2007). In addition, the in-task level of exertion that is experienced near the end of the exercise trial may intensify session RPE. This holds regardless of whether intensity was constant (Green et al. 2009), self-selected based on specific verbal prescriptions (Kilpatrick et al. 2009), or freely self-selected based on what the subject thought was a “good workout.” Therefore, it may be necessary to separately measure session RPE for the different segments of the previous exercise bout. This is termed segmented session RPE. In the post-exercise period, the subject is asked to estimate the average RPE for a specific segment (time-period) of a bout of exercise or PA that was just completed. Segmented session RPE can take the place of or be measured in addition to a full session RPE.

Haile and colleagues (2013a) asked subjects to rate session RPE and segmented session RPE following 20 min of self-selected treadmill exercise. Segmented session RPE values were rated for the first and second halves (first and second 10-min time-periods) of exercise. Each segmented session RPE value was similar to the momentary RPE values rated during its respective time-period. In addition, the mean of the two segmented session RPE values was similar to the mean momentary RPE for the total exercise session. Allowing the subjects to rate session RPE for each segment of the previous exercise bout resulted in a response that was representative of the mean of momentary RPE values. In this investigation, session RPE was also similar to the mean momentary RPE. Therefore, simply asking the subjects to focus on the different segments of exercise prior to rating session RPE may result in a response that represents the mean momentary RPE (Haile et al. 2013a).