Sex-related differences in ratings of perceived exertion and estimated time limit

Modeling of the Rating of Perceived Exertion Based on Heart Rate Using Machine Learning Methods

Rating of perceived exertion (RPE) can serve as a more convenient and economical alternative to heart rate (HR) for exercise intensity control. This study aims to explore the influence of factors, such as indicators of demographic, anthropometric, body composition, cardiovascular function and basic exercise ability on the relationship between HR and RPE, and to develop the model predicting RPE from HR. 48 healthy participants were recruited to perform an incrementally 6-stage pedaling test. HR and RPE were collected during each stage. The influencing factors were identified with the forward selection method to train Gaussian Process regression (GPR), support vector machine (SVM) and linear regression models. Metrics of R2, adjusted R2 and RMSE were calculated to evaluate the performance of the models. The GPR model outperformed the SVM and linear regression models, and achieved an R2 of 0.95, adjusted R2 of 0.89 and RMSE of 0.52. Indicators of age, resting heart rate (RHR), Central arterial pressure (CAP), body fat rate (BFR) and body mass index (BMI) were identified as factors that best predicted the relationship between RPE and HR. It is possible to use GPR model to estimate RPE from HR accurately, after adjusting for age, RHR, CAP, BFR and BMI.

Internal Training Load Perceived by Athletes and Planned by Coaches: A Systematic Review and Meta-Analysis

Background

Rating of perceived exertion (RPE) and session RPE (sRPE) has been widely used to verify the internal load in athletes. Understanding the agreement between the training load prescribed by coaches and that perceived by athletes is a topic of great interest in sport science.

Objective

This systematic review and meta-analysis aimed to investigate differences between the training/competition load perceived by athletes and prescribed/intended/observed by coaches.

Methods

A literature search (September 2020 and updated in November 2021) was conducted using PubMed, Web of Science, Embase, and SPORTDiscus databases. The protocol was registered in the Open Science Framework (osf.io/wna4x). Studies should include athletes and coaches of any sex, age, or level of experience. The studies should present outcomes related to the RPE or sRPE for any scale considering overall training/competition sessions (physical, strength, tactical, technical, games) and/or classified into three effort categories: easy, moderate, and hard.

Results

Twenty-seven studies were included in the meta-analysis. No difference was found between coaches and athletes for overall RPE (SMD = 0.19, P = 0.10) and overall sRPE (SMD = 0.05, P = 0.75). There was a difference for easy RPE (SMD = − 0.44, small effect size, P = 0.04) and easy sRPE (SMD = − 0.54, moderate effect size, P = 0.04). No differences were found for moderate RPE (SMD = 0.05, P = 0.74) and hard RPE (SMD = 0.41, P = 0.18). No difference was found for moderate (SMD = -0.15, P = 0.56) and hard (SMD = 0.20, P = 0.43) sRPE.

Conclusion

There is an agreement between coaches and athletes about overall RPE and sRPE, and RPE and sRPE into two effort categories (moderate and hard). However, there were disagreements in RPE and sRPE for easy effort category. Thus, despite a small disagreement, the use of these tools seems to be adequate for training monitoring.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40798-022-00420-3.

Upper- vs. Lower-Body Exercise Performance in Female and Male Cross-Country Skiers

Purpose: To investigate the interaction between exercise modality (i.e., upper- and lower-body exercise) and sex in physiological responses and power output (PO) across the entire intensity spectrum (i.e., from low to maximal intensity).

Methods: Ten male and 10 female cross-country (XC) skiers performed a stepwise incremental test to exhaustion consisting of 5 min stages with increasing workload employing upper-body poling (UP) and running (RUN) on two separate days. Mixed measures ANOVA were performed to investigate the interactions between exercise modalities (i.e., UP and RUN) and sex in physiological responses and PO across the entire exercise intensity spectrum.

Results: The difference between UP and RUN (ΔUP−RUN), was not different in the female compared with the male XC skiers for peak oxygen uptake (18 ± 6 vs. 18 ± 6 mL·kg−1·min−1, p = 0.843) and peak PO (84 ± 18 vs. 91 ± 22 W, p = 0.207). At most given blood lactate and rating of perceived exertion values, ΔUP−RUN was larger in the male compared with the female skiers for oxygen uptake and PO, but these differences disappeared when the responses were expressed as % of the modality-specific peak.

Conclusion: Modality-differences (i.e., ΔUP−RUN) in peak physiological responses and PO did not differ between the female and male XC skiers. This indicates that increased focus on upper-body strength and endurance training in female skiers in recent years may have closed the gap between upper- and lower-body endurance capacity compared with male XC skiers. In addition, no sex-related considerations need to be made when using relative physiological responses for intensity regulation within a specific exercise modality.

Entwicklung und Evaluation der Anstrengungsskala Sport

Aufgrund ihrer Einfachheit und Nutzerfreundlichkeit wird für die Erfassung der subjektiven Beanspruchungswahrnehmung in Training und Wettkampf bevorzugt die Category Ratio Scale (CR10-Skala) oder eine daran angelehnte Ein-Item-Skala eingesetzt. Die CR10-Skala stellt eine nicht-lineare, leicht positiv beschleunigte Funktion bezogen auf die Beanspruchung dar, die in der autorisierten deutschen Fassung mit „Anstrengungsempfinden“ übersetzt wird. Allerdings ist festzuhalten, dass die existierenden Skalen keine vollständigen Stufenbezeichnungen beinhalten und/oder die Stufenbezeichnungen Überschneidungen mit verwandten Konstrukten, z. B. Ermüdung zulassen. Die Anstrengungsskala Sport (ASS) zeichnet sich demgegenüber durch vollständige Stufenbezeichnungen und begriffliche Klarheit mit der komparativen Deklination des Adjektivs anstrengend aus. Auf der Grundlage einer rationalen Konstruktionsstrategie sowie einer systematischen Item-Analyse kann gezeigt werden, dass die Voraussetzungen für die Verwendung der ASS als Verhältnisskala gegeben sind, die eine zuverlässige und inhaltlich eindeutige Messung der Anstrengung gestattet.

The impact of physical activity rate on subjective well-being among North-Western Italian population during COVID-19 nationwide lockdown

BACKGROUND

Several factors influence subjective well-being, and one of them is the rate of physical activity. However, the possibilities to perform physical activity are compromised by the running COVID-19 pandemic. Thus, the present study aimed to explore the relationship between self-reported physical activity levels during COVID-19 and subjective well-being. Furthermore, our secondary aim was to investigate whether personal well-being was different between men and women and between people with different self-reported physical activity levels.

METHODS

Physical activity rate and subjective well-being were assessed using specific online surveys. Well-being was investigated using the 5-item World Health Organization Well-being Index while physical activity rates using the official Italian short form of IPAQ. Participation was voluntary, and people could fill the questionnaire simply by clicking on a specific link reachable via Social Networks or by email.

RESULTS

The final sample size was 595 Italian responders. Male and female were equally distributed (50,3% male and 49,7% female). The multiple regression indicated that the model was a significant predictor of subjective well-being (R2 =,070,F (3,59) = 14,68, p< 0.0001). The univariate ANOVA detected a statistically significant difference in subjective well-being perception between gender (p<0,05; ƞ²= ,01) and among physical activity rates ((whole sample: p<0,0001, ƞ²=0,03); Males: F(2,296)=4,364, p<0,01, ƞ²=0,03; Females: F(2,293)=5,256, p<0,001, ƞ²=0,04)). Tuckey's post hoc identified a difference between Low active and moderate active males (p< 0,01) and low active and very active females (p< 0,01).

CONCLUSIONS

More vigorous activities are necessary for women to reach the goal of feeling good and satisfied with life than men. Therefore, women should be encouraged to spend more time practising physical activity at a more vigorous rate. This outcome might help practitioners set specific home training programs to be advised during periods of social life restrictions as the running COVID-19 pandemic.

Is Rating of Perceived Exertion a Valuable Tool for Monitoring Exercise Intensity During Steady-State Conditions in Elite Endurance Athletes?

PURPOSE

Rating of perceived exertion (RPE) is a widely used tool to assess subjective perception of effort during exercise. The authors investigated between-subject variation and effect of exercise mode and sex on Borg RPE (6-20) in relation to heart rate (HR), oxygen uptake (VO2), and capillary blood lactate concentrations.

METHODS

A total of 160 elite endurance athletes performed a submaximal and maximal test protocol either during cycling (n = 84, 37 women) or running (n = 76, 32 women). The submaximal test consisted of 4 to 7 progressive 5-minute steps within ∼50% to 85% of maximal VO2. For each step, steady-state HR, VO2, and capillary blood lactate concentrations were assessed and RPE reported. An incremental protocol to exhaustion was used to determine maximal VO2 and peak HR to provide relative (%) HR and VO2 values at submaximal work rates.

RESULTS

A strong relationship was found between RPE and %HR, %VO2, and capillary blood lactate concentrations (r = .80-.82, all Ps < .05). The between-subject coefficient of variation (SD/mean) for %HR and %VO2 decreased linearly with increased RPE, from ∼10% to 15% at RPE 8 to ∼5% at RPE 17. Compared with cycling, running induced a systematically higher %HR and %VO2 (∼2% and 5%, respectively, P < .05) with these differences being greater at lower intensities (RPE < 13). At the same RPE, women showed a trivial, but significantly higher %HR and %VO2 than men (<1%, P < .05).

CONCLUSIONS

Among elite endurance athletes, exercise mode influenced RPE at a given %HR and %VO2, with greater differences at lower exercise intensities. Athletes should manage different tools to evaluate training based on intensity and duration of workouts.

Pain During a Marathon Run: Prevalence and Correlates in a Cross-Sectional Study of 1,251 Recreational Runners in 251 Marathons

This cross-sectional study aimed to obtain fundamental knowledge about pain during a marathon run. During the first seven months of 2007, announcements on websites of interest to marathon runners were used to recruit participants. A total of 1,251 runners (550 female runners) completed a 41-question online survey about the location and intensity of their primary pain during their last marathon and potentially related variables [perception of effort during the marathon, number of prior marathons run, typical pain intensity during training runs, percentage of training days with run-induced pain, highest intensity pain ever experienced]. Pain location was selected from a list of 27 specified body sites covering the entire body. Kilometer at which pain first occurred indexed pain threshold. Pain intensity at the primary location of pain was measured with a standardized, well-validated 0–10 pain intensity scale. Pearson correlations and multiple regression quantified the associations between average pain intensity and other variables. Sex-related differences in pain were tested using independent t-tests. Effort ratings (6–20) were added as a covariate in an ANCOVA to test if perceived effort accounted for possible sex-related differences in pain. Based on the available research, it was hypothesized that: (i) most runners would report moderate intensity pain, (ii) pain would be associated with both exercise intensity during the marathon and pain during training, and (iii) after adjusting for expected sex-related differences in perceived effort, females would experience pain earlier and rate the pain intensity as higher. All but two runners (99.8%) reported pain during a marathon, and most frequently in the anterior/medial thigh (17.1%), hamstring (10%), and calf (9.3%) locations. Pain threshold occurred at 25.3 ± 9.8 km (15.7 ± 6.1 miles) and the overall pain intensity of the run was 5.26 ± 2.45. No sex-related pain differences were found. Overall pain intensity during a marathon was significantly associated with: pain intensity during training runs (r = 0.39), percentage of training days with run-induced pain (r = 0.23), highest intensity pain ever experienced (r = 0.23), number of prior marathons (r = −0.18), and intensity of effort (r = 0.11) (all P < 0.001). Most runners experience moderate to very strong intensity pain during a marathon; the pain was independent of biological sex, and the pain is weakly associated with marathon race experience, pain during training, race effort, and the highest intensity of pain ever experienced.

Effects of preferred music on physiological responses, perceived exertion, and anaerobic threshold determination in an incremental running test on both sexes

This study aimed to investigate and compare the effects of preferred music on anaerobic threshold determination in an incremental running test, as well the physiological responses and perceived exertion at this intensity, in physically active men and women. Additionally, by using area under the curve (AUC) analysis of the parameters of interest during the graded test, we studied the effects of music at two physiological moments-before and after anaerobic threshold intensity (iAT)-in men and women. Twenty (men = 10; women = 10) healthy and active participants completed four visits to the laboratory. The first and second sessions were used for sample characterization. In the third and fourth sessions, participants performed an incremental running test (started at 7 km.h-1 with increments of 1 km.h-1 at each 3-minute stage) under preferred music and non-music conditions. Blood lactate ([Lac]), heart rate (HR), and perceived exertion were measured by two scales (RPEBorg and the estimation of time limit ‒ ETL) during all tests, and the total time of effort (TT) was considered as performance. Individual curves of the "intensity vs blood lactate" analyzed by the bissegmentation method provide the iAT and the AUC of [Lac], HR, RPEBorg, and ETL before and after the iAT attainment were calculated. The iAT for men (non-music: 11.5±0.9km.h-1 vs music: 11.6±1.1km.h-1) and women (non-music: 9.8±0.7km.h-1 vs music: 9.7±0.7km.h-1) was not affected by music, and for both sexes, there was no difference between non-music and music conditions in all variables obtained at iAT. The AUC of all variables were not affected by music before the iAT attainment. However, [Lac], HR, and RPEBorg presented higher values of AUC after iAT for the female group with preferred music. This may be due to the fact that 70% of women have increased TT under music conditions. Overall, preferred music did not affect the iAT determination in an incremental running test. However, some physiological responses and perceived exertion after iAT of female subjects seems to be influenced by preferred music.

Influence of Sodium Glucose Cotransporter 2 Inhibition on Physiological Adaptation to Endurance Exercise Training

CONTEXT

The combination of two beneficial antidiabetes interventions, regular exercise and pharmaceuticals, is intuitively appealing. However, metformin, the most commonly prescribed diabetes medication, attenuates the favorable physiological adaptations to exercise; in turn, exercise may impede the action of metformin.

OBJECTIVE

We sought to determine the influence of an alternative diabetes treatment, sodium glucose cotransporter 2 (SGLT2) inhibition, on the response to endurance exercise training.

DESIGN, PARTICIPANTS, AND INTERVENTION

In a randomized, double-blind, repeated measures parallel design, 30 sedentary overweight and obese men and women were assigned to 12 weeks of supervised endurance exercise training, with daily ingestion of either a placebo or SGLT2 inhibitor (dapagliflozin: ≤10 mg/day).

OUTCOME MEASUREMENTS AND RESULTS

Endurance exercise training favorably modified body mass, body composition (dual-energy x-ray absorptiometry), peak oxygen uptake (graded exercise with indirect calorimetry), responses to standardized submaximal exercise (indirect calorimetry, heart rate, and blood lactate), and skeletal muscle (vastus lateralis) citrate synthase activity (main effects of exercise training, all P < 0.05); SGLT2 inhibition did not influence any of these physiological adaptations (exercise training × treatment interaction, all P > 0.05). However, after endurance exercise training, fasting blood glucose was greater with SGLT2 inhibition, and increased insulin sensitivity (oral glucose tolerance test/Matsuda index) was abrogated with SGLT2 inhibition (exercise training × treatment interaction, P < 0.01).

CONCLUSION

The efficacy of combining two beneficial antidiabetes interventions, regular endurance exercise and SGLT2 inhibition, was not supported. SGLT2 inhibition blunted endurance exercise training-induced improvements in insulin sensitivity, independent of effects on aerobic fitness or body composition.

Associations between Thermal and Physiological Responses of Human Body during Exercise

In this study, thermal behaviours of the athletes were investigated with respect to thermal comfort and exercise intensity. The relationship between an index for analysing thermal comfort (Predicted Mean Vote: PMV) and Rating of Perceived Exertion (RPE) which shows exercise intensity and exhaustion level was evaluated. Eleven moderately trained male athletes (V˙O_2max 54 ± 9.9 mL∙min⁻¹∙kg⁻¹) had volunteered for the study (age: 22.2 ± 3.7 years; body mass: 73.8 ± 6.9 kg; height: 181 ± 6.3 cm; Body surface area (BSA): 1.93 ± 0.1 m²; body fat: 12.6% ± 4.2%; V˙O_2max: 54 ± 9.9 mL∙min⁻¹∙kg⁻¹). Experiments were carried out by using a cycle ergometer in an air-conditioned test chamber which provided fresh air and had the ability to control the temperature and relative humidity. The study cohort was divided into two groups according to maximal oxygen consumption levels of the participants. Statistical analyses were conducted with the whole study cohort as well as the two separated groups. There was a moderate correlation between PMV and RPE for whole cohort (r: −0.51). When the whole cohort divided as low and high aerobic power groups, an average correlation coefficient at high oxygen consumption cohort decreased to r: −0.21, while the average correlation coefficient at low oxygen consumption cohort increased to r: −0.77. In conclusion, PMV and RPE have a high correlation in less trained participants, but not in the more trained ones. The case may bring to mind that thermal distribution may be better in high aerobic power group in spite of high RPE and thus the relation between PMV and RPE is affected by exercise performance status.

Prediction of performance reduction in self-paced exercise as modulated by the rating of perceived exertion

PURPOSE

Rating of perceived exertion (RPE) is a scale of exercise difficulty and has been hypothesized to be a regulator of work rate during self-pacing. The goal of this work was to develop a dynamic prediction of RPE and to characterize the control strategy employed to reduce work rate during self-paced exercise using RPE as feedback.

METHODS

Training and test data were acquired from the literature to develop a linear regression of RPE as a function of four physiological variables: core temperature, mean-weighted skin temperature, metabolic rate, and integral of relative oxygen consumption (R (2) = 0.85). A thermoregulatory model was used to predict core and mean-weighted skin temperature. Utilizing self-paced cycling and running data from the literature, we characterized reductions in work rate with a proportional-derivative control algorithm with RPE as feedback.

RESULTS

Bland-Altman analysis revealed the necessity to parameterize RPE equations for untrained and endurance-trained individuals. Afterwards, dynamic predictions of RPE were accurate for a wide range of activity levels and air temperatures for walking, running, and cycling (LoA and bias of 2.3 and -0.03, respectively). For self-paced exercise, the control algorithm characterized the trend and magnitude of work rate reductions for cycling and running, and showed regulated RPE to be less conservative for shorter vs. longer duration exercise.

CONCLUSIONS

A novel methodology to characterize self-paced work intensity, based upon dynamic physiologic response, is provided. The complete model is a useful tool that estimates performance decrements during self-paced exercise and predicts tolerance time for exhaustive fixed-rate exercise.

High-intensity interval training, solutions to the programming puzzle: Part I: cardiopulmonary emphasis

High-intensity interval training (HIT), in a variety of forms, is today one of the most effective means of improving cardiorespiratory and metabolic function and, in turn, the physical performance of athletes. HIT involves repeated short-to-long bouts of rather high-intensity exercise interspersed with recovery periods. For team and racquet sport players, the inclusion of sprints and all-out efforts into HIT programmes has also been shown to be an effective practice. It is believed that an optimal stimulus to elicit both maximal cardiovascular and peripheral adaptations is one where athletes spend at least several minutes per session in their 'red zone,' which generally means reaching at least 90% of their maximal oxygen uptake (VO2max). While use of HIT is not the only approach to improve physiological parameters and performance, there has been a growth in interest by the sport science community for characterizing training protocols that allow athletes to maintain long periods of time above 90% of VO2max (T@VO2max). In addition to T@VO2max, other physiological variables should also be considered to fully characterize the training stimulus when programming HIT, including cardiovascular work, anaerobic glycolytic energy contribution and acute neuromuscular load and musculoskeletal strain. Prescription for HIT consists of the manipulation of up to nine variables, which include the work interval intensity and duration, relief interval intensity and duration, exercise modality, number of repetitions, number of series, as well as the between-series recovery duration and intensity. The manipulation of any of these variables can affect the acute physiological responses to HIT. This article is Part I of a subsequent II-part review and will discuss the different aspects of HIT programming, from work/relief interval manipulation to the selection of exercise mode, using different examples of training cycles from different sports, with continued reference to T@VO2max and cardiovascular responses. Additional programming and periodization considerations will also be discussed with respect to other variables such as anaerobic glycolytic system contribution (as inferred from blood lactate accumulation), neuromuscular load and musculoskeletal strain (Part II).

Comparação das respostas fisiológicas e perceptuais obtidas durante caminhada na esteira em ritmo autosselecionado entre os sexos

O objetivo do presente estudo foi comparar as respostas fisiológicas e perceptuais entre os sexos durante a caminhada na esteira em ritmo autosselecionado. Participaram 17 homens e 17 mulheres, fisicamente ativos, com média de idade de 23,32 ± 3,06 anos, submetidos a duas sessões experimentais: (I) avaliação antropométrica e teste incremental máximo, e (II) um teste de 20 minutos de caminhada na esteira em ritmo autosselecionado. Para a análise estatística, empregou-se teste t de Student para medidas independentes no intuito de verificar as possíveis diferenças entre os sexos, adotando p < 0,05. A velocidade de caminhada autosselecionada pela amostra masculina foi superior à verificada na feminina (1,65 ± 0,18 e 1,50 ± 0,12m·seg-1, respectivamente) o que consequentemente resultou em maior <img src="/img/revistas/rbme/v16n4/v7_dot.gif" align="absmiddle">O2 absoluto nos homens comparado às mulheres (21,2 ± 5,5 e 18,3 ± 2,7, respectivamente). No entanto, ambos os sexos buscaram caminhar em mesma intensidade relativa % <img src="/img/revistas/rbme/v16n4/v7_dot.gif" align="absmiddle">O2máx, (37,5 ± 10,7 homens e 40,3 ± 7,2 mulheres). Em relação à percepção subjetiva de esforço (PSE), podemos verificar que ambos os sexos não demonstraram diferenças significativas (10,2 ± 1,0 homens e 9,8 ± 1,2 mulheres). Os achados do presente estudo demonstram que, independente do sexo, jovens adultos fisicamente ativos autosselecionaram similar intensidade relativa que refletiu em similar PSE. Além disso, a caminhada em intensidade autosselecionada demonstra-se como estímulo insuficiente para proporcionar melhora no condicionamento cardiorrespiratório nesta população.

Overall and peripheral ratings of perceived exertion during a graded exercise test to volitional exhaustion in individuals of high and low fitness

This study assessed the relationship between differentiated ratings of perceived exertion (RPE) and heart rate with oxygen uptake (VO2) during two graded exercise tests (GXT) to exhaustion on a cycle ergometer in 49 men and women (19-50 years) of high and low fitness. The study also assessed whether sub-maximal RPE values elicited during the GXTs could provide appropriate estimates of maximal aerobic power (VO2max) Peripheral RPE (RPEP) was higher than overall RPE (RPEO) at exhaustion in both groups (P<0.001), but the reliability of the terminal RPEO was higher (0.75 and 0.40, respectively). Fitness did not moderate the relationship of RPEO and RPEP with VO2 during the GXTs (P>0.05). However, the correlation for RPEP and VO2 was higher for women compared to men (0.98 and 0.96, respectively, P<0.05), although this is of little practical significance. In both groups, RPEO was almost as highly correlated with VO2 as heart rate during GXTs terminated at exhaustion (approximately 0.955-0.980). There were no differences between predicted and measured VO2max when VO2 values were extrapolated from sub-maximal RPEO (13, 15 and 17) intensities (42.1+/-12.5, 43.4+/-11.5, 44.2+/-11.3 and 43.3+/-10.0 ml kg(-1) min(-1), respectively). However, VO2max predicted from sub-maximal RPEP intensities was significantly lower (P<0.05). In conclusion, terminal RPEO was a more reliable measure of the RPE, and provided more accurate estimates of VO2max in healthy participants of high and low fitness when elicited from sub-maximal exercise intensities.

Prediction of maximal oxygen uptake from the ratings of perceived exertion and heart rate during a perceptually-regulated sub-maximal exercise test in active and sedentary participants

This study assessed whether the accuracy of predicting maximal oxygen uptake (VO2max) from sub-maximal heart rate (HR) and ratings of perceived exertion (RPE) values was moderated by gender and habitual activity. In total, 27 men and 18 women completed two GXTs to determine VO2max and three perceptually-regulated GXTs, incremented by RPE 9, 11, 13, 15 and 17. The RPE and HR were individually regressed against VO2max (approximately 0.96) to enable predictions of VO2max. The VO2max was predicted from three RPE ranges (9-17, 9-15, 9-13). The RPE ranges were extrapolated to RPE(19), RPE(20) and age-predicted maximal HR (HRmax(pred)). ANOVA revealed no differences between measured and predicted VO2max (P > 0.05) when the RPE range 9-17 was extrapolated to RPE(19) and HRmax(pred). Extrapolation of RPE 9-17 to RPE(20) overestimated VO2max (P < 0.05), but no differences were observed when predicted from the RPE ranges 9-15 and 9-13. The prediction of VO2max was not moderated by gender or activity status. Hierarchical regression analysis revealed that HR explained additional variance in VO2max when added to the RPE (2%). Hierarchical multiple regression analysis also indicated that VO2max was significantly correlated with power output at sub-maximal RPE values of 13 and 15 (P < 0.01) in men and women. The addition of HRmax(pred) improved the accuracy of the prediction equation for men (P = 0.05) but not for women. The study confirmed the validity of estimating VO2max from perceptually-regulated, sub-maximal GXT and indicated the potential utility of regression analysis to gauge appropriate sub-maximal exercise intensities.