Rating Of Perceived Exertion Levels Research Articles

The relationship between prescribed ratings of perceived exertion and force production in repeated isometric contractions

Ratings of perceived exertion (RPE) are frequently used to monitor and prescribe exercise intensity. However, studies examining the shape and robustness of how feelings of effort map onto objective outputs are limited and report inconsistent results. To address this, we investigated whether (1) producing isometric forces according to RPE levels reliably leads to differences in force output, (2) if feelings of effort map linearly or non-linearly onto force output, and (3) if this mapping is robust when visual feedback and social facilitation are present. In a counterbalanced repeated measures design, N = 26 participants performed isometric handgrip contractions prescribed by ten levels of the Borg CR-10 scale. They did so either with or without the availability of concurrent visual feedback regarding their force production, and in the presence or absence of another person performing the same task simultaneously. We found that subjects reliably produced different force outputs that corresponded to each RPE level. Furthermore, concurrent visual feedback led to a linearization of force output, while in the absence of feedback, the produced forces could also be described by quadratic and cubic functions. Exploratory post-hoc analyses revealed that participants perceived moderate RPE levels to be more challenging to produce. By shedding light on the dynamic nature of the mapping between RPE and objective performance, our findings provide helpful insights regarding the utility of RPE scales.

ASSESSMENT OF A SELF-PACED PROTOCOL FOR TESTING AEROBIC CAPACITY IN SCI INDIVIDUALS

https://youtu.be/u89x4ivgoIc BACKGROUND Underwater treadmill (UT) exercise is a recent and sparsely tested modality that may be beneficial for those with incomplete spinal cord injury (iSCI). Currently, VO2max and HRmax have not been assessed during UT exercise among those with iSCI. This study's purpose was to determine if a rating of perceived exertion (RPE) based max exertion protocol used with a motorized UT can elicit criterion-based max physiological responses among those with and without iSCI. METHODS Healthy adult males with iSCI (n=4; Age=49.8 +/- 3.9 yrs) and without iSCI (n=4; Age=50.0 +/- 7.2 yrs) participated. Borg OMNI RPE scale was used by participants to estimate intensity of exercise. Each participant reported to the lab on two occasions. On visit one, they completed informed consent papers and familiarization with the RPE scale and UT exercise. On visit two, they completed a speed-based, self-regulated incremental exercise test on the UT. Prior to all testing, the UT was filled and set to 92°F. Upon arrival, HR monitor and mask for gas collection were donned. Water height was modified to the xiphoid process. The test consisted of rest, warm-up, incremental exercise, and active recovery phases. For warm-up, treadmill speed was adjusted to 0.5 mph for 3 minutes. After walking 3 minutes, speed was increased to 0.75 mph for another 3 minutes. The incremental exercise phase consisted of four stages, 3 minutes in duration, totaling 12 minutes. For each stage, participants self-selected a speed perceived to correspond to RPE levels: 3, 5, 7, and 10. Treadmill speed was hidden from participants. At each stage's start, speed was only adjusted during the first minute until reaching the proper RPE. During the final stage, treadmill speed could be changed freely until volitional exhaustion. The test ended when volitional exhaustion was reached, at which point the speed was lowered for an active recovery. An independent samples t-test was used to compare time (minutes) until volitional exhaustion. Separate independent samples t-tests were used to compare the highest achieved HR and VO2 values. RESULTS All iSCI participants achieved a VO2peak. Only 1 participant without iSCI achieved a VO2max. Mean VO2 was significantly lower, t(6)=3.81, p=.027, for those with iSCI (13.88 +/- 10.57 mL/kg/min) than those without iSCI (34.50 +/- 2.38 mL/kg/min). CONCLUSION This study shows that the UT is a safe modality for graded exercise testing for those with and without iSCI. An RPE-regulated protocol may not be effective for eliciting criterion-based maximal aerobic results with the UT, but was well tolerated by those with iSCI. Those with iSCI may have lacked lower limb strength to achieve max workloads. Being able to use the UT to test peak aerobic fitness allows clinicians to track improvements in economy following UT training. More research of this modality is encouraged with larger samples to further evaluate potential testing protocols among this population.

Examining the alignment between subjective effort and objective force production.

Ratings of Perceived Exertion (RPE) are frequently used to prescribe exercise intensity. A central assumption of using RPE scales is that the subjective perception of effort maps onto objective performance in a consistent way. However, the degree and shape of how RPE aligns with objective performance is not fully understood. Here, we investigate the degree and shape of alignment, as well as how time (i.e., how frequently an effort needs to be performed) and mental effort (i.e., if one has to invest mental effort and physical effort) correspond with the alignment. In a randomized within-subjects experiment, we used a grip-to-scale method that asked participants (N = 43) to repeatedly squeeze a handgrip dynamometer with four to-be-produced RPE target levels relative to their subjective maximum strength (representing 20%, 40%, 60%, or 80%). We found that the RPE-force alignment was not the same across RPE-levels: Whereas subjective differences from 20-40% and 40-60% were met by comparable differences in produced force, a substantially larger difference was observed for the 60-80% interval. Interestingly, exploratory post-hoc analyses revealed that this was mirrored by an increase in variance at the higher effort levels. In addition, at constant RPE-levels, participants produced less force over time, and this effect was more pronounced at lower RPE target levels. Lastly, anticipating mental effort after the physical effort slightly altered the alignment as a function of the to-be-produced RPE-level and experimental duration. Taken together, our results indicate that the mapping of perceived effort on objective performance is intricate, and several factors affect the degree and shape of how RPE and performance align. Understanding the dynamic adjustment of RPE-performance alignment across different RPE levels is particularly relevant for contexts that use RPE as a tool for training load prescription.

Evaluation of Functional Capacity and Rate of Perceived Exertion through Six-minute Walk Test in Pre and Post-haemodialysis Patients with Chronic Kidney Disease: A Prospective Cohort Study

Introduction: Chronic Kidney Disease (CKD) is a condition that affects multiple organs, including the respiratory system. Haemodialysis is a commonly used treatment for End-stage Renal Disease (ESRD), but it can lead to respiratory issues, reduced muscle strength, decreased functional capacity, and lower quality of life. The Six-minute Walk Test (6MWT) is widely accepted for assessing functional capacity in CKD patients. Aim: To evaluate the impact of haemodialysis on the functional capacity and Rate of Perceived Exertion (RPE) in patients with CKD by employing the 6MWT as a comprehensive measure. Materials and Methods: A prospective cohort study was conducted in the Department of Nephrology and Dialysis ward at MGM Hospital, Aurangabad, Maharashtra, India, from April 2020 to December 2021. A total of 73 patients were included in the present study. The primary outcome measure was the walked distance assessed using the 6MWT, and secondary outcomes are the RPE were evaluated using the Modified Borg Scale (MBS). Gait speed was also measured. Baseline demographic data, laboratory investigations, and associated co-morbidities were collected. The tests were performed before and immediately after the haemodialysis session. Data were analysed using the Student’s t-test and one-way Analysis of Variance (ANOVA), and the statistical significance level was setup at p<0.05. Results: The mean age of the study participants was 44±8.25 years. The study found a significant reduction in walking distance (mean of 85 meters) after the haemodialysis session compared to the pre-session. The post-haemodialysis session showed a significant increase in RPE and fatigue levels (p=0.0001). Additionally, a significant difference in gait speed (p=0.0001) was observed between the pre and post-haemodialysis sessions. Conclusion: The present study findings indicate a significant decrease in walking distance and noteworthy increase in RPE and fatigue levels following haemodialysis sessions in CKD patients. These results emphasise the impact of haemodialysis on functional capacity and perceived exertion among individuals with this condition.

Analysis of physiological tremors during different intensities of armcurl exercises using wearable three-axis accelerometers in healthy young men: a pilot study.

The purpose of this pilot study was to determine whether physiological tremors (PTs) assessed using an accelerometer could be used to evaluate resistance exercise intensity. Twenty healthy young men with no prior experience of resistance exercise were recruited. Different intensities (resting, 30%, 50%, and 70% of their predetermined one-repetition maximum (1-RM)) of arm-curl exercise were used to elicit PT. The total work was held equally by varying the number of repetitions, with five sets for each intensity. Sessions of varying intensities were performed randomly with a washout period of at least a week. PT responses were recorded during exercise using accelerometers (3-axis) attached to the wrist and ear. Electromyography (EMG) data were obtained from the biceps brachii muscle during exercise. PT and EMG data were expressed as the average root mean square index. The EMG amplitude increased significantly as exercise intensity increased. Furthermore, PT amplitude significantly increased as exercise intensity increased. Moreover, the Borg rating of perceived exertion (RPE) and lactic acid levels increased significantly. The wrist PT was related to ear PT, EMG, RPE, and lactic acid levels. Additionally, ear PT was associated with EMG, RPE, and lactic acid levels. This pilot study identified changes in PT during resistance exercise at different intensities. We suggest that the use of PT analyses during these exercises provides a more intuitive delineation of resistance exercise intensity and fatigue.

Effect of Face Masks on Physiological and Perceptual Responses during 30 Minutes of Self-Paced Exercise in Older Community Dwelling Adults.

This study examined the effects of different types of masks (no mask, surgical mask (SM), and N95-mask) on physiological and perceptual responses during 30-min of self-paced cycle ergometer exercise. This study was a prospective randomly assigned experimental design. Outcomes included workload (Watts), oxygen saturation (SpO2), end-tidal carbon dioxide (PetCO2), heart rate (HR), respiratory rate (RR), rating of perceived exertion (RPE), and rating of perceived dyspnea (RPD). Volunteers (54–83 years (n = 19)) completed two familiarization sessions and three testing sessions on an air braked cycle ergometer. No significant difference was found for condition x time for any of the dependent variables. RPE, RPD, and PetCO2 were significantly higher with an N95-mask vs. no mask (NM) ((p = 0.012), (p = 0.002), (p < 0.001)). HR was significantly higher with the SM compared to the NM condition (p = 0.027) (NM 107.18 ± 9.96) (SM 112.34 ± 10.28), but no significant difference was found when comparing the SM to the N95 condition or when comparing the N95condition to the NM condition. Watts increased across time in each condition (p = 0.003). Initially RR increased during the first 3 min of exercise (p < 0.001) with an overall gradual increase noted across time regardless of mask condition (p < 0.001). SpO2 significantly decreased across time but remained within normal limits (>95%). No significant difference was found in Watts, RR, or SpO2 regardless of mask condition. Overall, the N95mask was associated with increased RPE, RPD, and PetCO2 levels. This suggests trapping of CO2 inside the mask leading to increased RPE and RPD.

Discomfort And Ratings Of Perceived Exertion To Practical Vs. Traditional Blood Flow Restriction Resistance Exercise

Elastic knee wraps are used to produce blood flow restriction (BFR) but it is unclear how discomfort and perceived exertion may compare to more traditional ways of producing BFR such as nylon cuffs where the pressure is known. PURPOSE: To investigate how elastic knee wraps (practical) compare in ratings of perceived exertion (RPE) and discomfort after exercising to failure when compared to nylon cuffs (traditional) or low and high loads without BFR. METHODS: Nine participants (male=7, female=2) completed this study. The average age and body mass index were 22 (4) years and 25.4 (1.5) kg/m2. Each participant completed six conditions, in a randomized order, of unilateral knee extension exercise to failure for four sets. Two conditions (30% one-repetition maximum, 1-RM) included elastic knee wraps that were either stretched by two inches from resting length (Practical-Low) or they were stretched to a new length that was 85% of the thigh circumference (Practical-High). Two more conditions (30%-1RM) used nylon cuffs that were inflated to either 80% (BFR-High) or 40% (BFR-Low) of arterial occlusion pressure. The last two conditions had no restriction stimulus and were 30% 1-RM (LL) or 70% 1-RM (HL). Discomfort (0-10) and RPE (6-20) were measured before exercise and at the end of the four sets. The change scores from before exercise to the end of set 4 were used for analysis. Friedman’s test and Conover’s post hoc test were used to determine if there was a difference in discomfort and RPE between conditions. Statistical significance was set at p<0.05. RESULTS: Practical-High had larger changes in discomfort compared to HL (8 vs 6, p=0.007) and LL (8 vs 6, p=0.018). Practical-Low had a smaller change in discomfort compared to BFR-High (7 vs. 9, p=0.028) but it was not different from BFR-Low (7 vs. 7, p=0.450). No differences were found between Practical-High vs. BFR-High (8 vs. 9, p=0.211) or Practical-High vs. BFR-Low (8 vs 7, p=0.316). Practical-Low had smaller changes in RPE compared to BFR-High (12 vs 11, p=0.024) but there was no difference in RPE between Practical-High and the other conditions (p>0.05). CONCLUSIONS: When exercising to failure, both discomfort and RPE are impacted by the pressure used and elastic knee wraps can produce changes in discomfort and RPE levels that are comparable to high pressure BFR.

Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis

BackgroundCitrulline is one of the non-essential amino acids that is thought to improve exercise performance and reduce post-exercise muscle soreness. We conducted a systematic review and meta-analysis to determine the effect of citrulline supplements on the post-exercise rating of perceived exertion (RPE), muscle soreness, and blood lactate levels. MethodsA random effects model was used to calculate the effect sizes due to the high variability in the study design and study populations of the articles included. A systematic search of PubMed, Web of Science, and ClinicalTrials.gov was performed. Eligibility for study inclusion was limited to studies that were randomized controlled trials involving healthy individuals and that investigated the acute effect of citrulline supplements on RPE, muscle soreness, and blood lactate levels. The supplementation time frame was limited to 2 h before exercise. The types and number of participants, types of exercise tests performed, supplementation protocols for L-citrulline or citrulline malate, and primary (RPE and muscle soreness) and secondary (blood lactate level) study outcomes were extracted from the identified studies. ResultsThe analysis included 13 eligible articles including a total of 206 participants. The most frequent dosage used in the studies was 8 g of citrulline malate. Citrulline supplementation significantly reduced RPE (n = 7, p = 0.03) and muscle soreness 24-h and 48-h after post-exercise (n = 7, p = 0.04; n = 6, p = 0.25, respectively). However, citrulline supplementation did not significantly reduce muscle soreness 72-h post-exercise (n = 4, p = 0.62) or lower blood lactate levels (n = 8, p = 0.17). ConclusionCitrulline supplements significantly reduced post-exercise RPE and muscle soreness without affecting blood lactate levels.

Caffeine: Does Drinking Coffee Alter Performance and RPE Levels of a Teenage Athlete in both Aerobic and Anaerobic Exercises?

The purpose of the study is to determine if ingesting caffeine in the form of coffee prior to workouts can enhance performance and alter Borg Rating of Perceived Exertion (RPE) of teenage athletes for both endurance (aerobic) and strength (anaerobic) exercises. Our hypotheses are that caffeine lowers RPE for both endurance and strength exercises and that it enhances performance in endurance, but not strength, exercises.To answer this question, we analyzed a 16-year-old high school athlete (myself) for a total of 12 days: 3 days consuming a cup of coffee prior to running, 3 days consuming a cup of coffee 1 hour prior to performing strength exercises, and 3 days without consuming a cup of coffee prior to exercise for each exercise type. For the endurance test, the athlete ran two miles as fast as they could. Average heart rate and total time of the run were analyzed for three days with coffee and three days without, as well as RPE levels. For the strength test, the athlete performed as many push-ups as possible in a one-minute time frame. The results showed that caffeine ingestion prior to exercise enhanced endurance, but had no impact on strength. Additionally, though RPE was lower for the endurance test, RPE remained unchanged for the strength test. Thus, the effect of drinking coffee in aerobic and anaerobic exercises were evaluated through several measures in this study, providing support that caffeine has an effect on aerobic exercises as opposed to anaerobic exercises.

Aerobic exercise with blood flow restriction affects mood state in a similar fashion to high intensity interval exercise

We investigated the acute effects of aerobic exercise with blood flow restriction (BFR) on mood state in American football athletes. Twenty-two male American football athletes were randomly assigned to three experimental conditions: 1) aerobic exercise (AE: 40% VO2max), 2) aerobic exercise with BRF (AE + BFR: 40% VO2 max), and 3) high-intensity interval exercise (HIIE: 80% and 40% VO2max during exercise and the active intervals, respectively). Mood state and total mood disturbance (TMD) were assessed before, immediately post, and 1 h post-exerciser. Ratings of perceived exertion (RPE) were measured 30 min post-exercise. AE + BFR and HIIE significantly (p < 0.05) increased fatigue and tension compared to baseline immediately post-exercise, whereas vigor significantly (p < 0.05) decreased at the same time point for both conditions. TMD increased significantly (p < 0.05) for AE + BFR and HIIE immediately post-exercise and it remained elevated up to 1 h post-exercise for AE + BFR. AE did not significantly (p > 0.05) affect mood state or TMD and it was significantly (p < 0.05) lower than AE + BFR and HIIE. AE + BFR and HIIE also elicited significantly (p < 0.05) greater RPE levels than AE 30 min post-exercise. Therefore, AE + BFR induces acute impairments in mood state and RPE levels in a similar fashion to HIIE.

Blood-Flow Restriction Resistance Exercise Promotes Lower Pain and Ratings of Perceived Exertion Compared With Either High- or Low-Intensity Resistance Exercise Performed to Muscular Failure.

Given the comparable muscle hypertrophy constantly observed between blood-flow restriction exercise (BFR-RE) and conventional resistance exercise, understanding their particular rating of perceived exertion (RPE) and pain may help to better prescribe exercise at a low-discomfort level, thus increasing its feasibility. Randomized crossover study. To compare the RPE and pain response between conventional high- (HI-RE) and low-intensity resistance exercise (LI-RE) protocols to failure with a nonmuscular failure LI-RE associated with BFR-RE. A total of 12 men (age: 20 [3]y; body mass: 73.5 [9]kg; height: 174 [6]cm). Four sets of 45° leg-press exercises in 3 different conditions: (1)BFR-RE (15 repetitions; 30% 1-repetition maximum), (2)HI-RE (80% 1-repetition maximum to muscular failure), and (3)LI-RE (30% 1-repetition maximum to muscular failure). RPE and pain were assessed immediately before exercise session and after the end of each of the 4 sets. RPE and pain levels increased throughout the exercise sets for all RE protocols (all, Ps < .05). HI-RE and LI-RE protocols showed similar increase in RPE and pain levels during all exercise sets (P < .05); however, both protocols demonstrated higher RPE and pain response compared with BFR-RE after each of the 4 sets (all Ps < .05 between-group comparisons). Our results demonstrated that both HI-RE and LI-RE to muscular failure resulted in similar and significant increases in RPE and pain levels, regardless of exercise intensity. In addition, nonmuscular failure BFR-RE also increased RPE and pain response, however, to a lower extent compared with either HI-RE or LI-RE.

Peer-Reviewed Abstracts

Background/Purpose: The US Department of Health and Human Services recommends that children participate daily in 60 minutes of moderate to vigorous physical activity (MVPA). A threshold of >4.0 METs (metabolic equivalent of task) is considered MVPA in children. Physical education classes are ideal settings for the promotion of MVPA through the practice of continuous (walking, running) and discrete (kicking, throwing, striking) skills. Recent research in adults has determined the energy expenditure of discrete skill practice to be high while participants’ rate of perceived exertion (RPE) was low. The replication of this phenomenon in children would provide evidence for the inclusion of discrete skill practice in curricula aiming to promote MVPA. Thus, this study examined energy expenditure (METs), rate of perceived exertion (RPE), and level of fun during object projection skill performance (kicking, throwing, and striking) at three different practice intervals in children. Method: Children (N = 42, Mage = 8.1 ± 0.8 years) participated in three nine-minute experimental sessions where participants performed rounds of 5 kicks, 5 throws, and 5 strikes in blocked fashion, at three practice intervals (i.e., 30, 12, and 6 seconds). Each participant completed the three sessions in a randomized order. Participants were instructed to perform all trials with maximum effort and to report their RPE (1 “Not tired at all” – 10 “So tired, I can’t go anymore”) and level of fun (1 “Not fun at all” – 10 “The most fun I’ve ever had”) using 10-point scales. The average energy expenditure (METs) during minutes 4-8 of each nine-minute session were calculated using a COSMED K4b2 gas analyzer. Analysis/Results: Three one-way repeated measures ANOVAs for METs, RPE, and fun were conducted to examine differences across groups and sex. Data indicated a main effect for interval condition (F = 94.36, p < .001, η2 = 0.605) with decreased interval times between performance trials yielding significantly higher METs across conditions (4.5 ± 0.8, 6.3 ± 1.3, 8.3 ± 1.6 at 30-, 12-, 6-sec interval respectively). There also was a main effect for sex (F = 52.28, p < .001, η2 = 0.305), with boys demonstrating higher METs at each performance trial interval. RPE and fun analyses determined a main effect for each interval (RPE; F = 91.16, p < .001, fun; F = 96.61, p<.001) with no difference in gender at each interval. The average RPE responses were low (3.3 ± 1.8, 4.1 ± 2.2, and 4.9 ± 2.7 at 30-, 12- and 6-sec interval respectively) while average fun levels remained high (8.0 ± 1.4, 8.3 ± 1.4, and 8.7 ± 1.4 at 30-, 12-, 6-sec interval respectively). Conclusions: Results indicate that skill practice in all three interval conditions resulted in MVPA. Boys and girls reported equivalent low levels of RPE and high levels of fun. These data demonstrate that the practice of discrete skills yield high levels of energy expenditure (METs), low levels of perceived exertion, and high levels of fun. This study provides positive evidence for the inclusion of discrete skills in physical activity interventions and physical education curricula attempting to promote MVPA.

Can Match-Mimicking Intermittent Practice Be Used as a Simulatory Training Mode of Competition Using Olympic Time Frame in Elite Taekwondo Athletes?

Aim: The physiological realities between Taekwondo (TKD) simulation kicking training and TKD competition according to the Olympic time frame remain unclear. The purpose of this study is to establish an Olympic match-simulated kicking model and compare its effects with real TKD competition on physiological challenges and hormonal responses during serial matches in elite athletes.Method: Sixteen elite TKD athletes randomly were assigned into either a TKD match-simulated kicking group (TMSK; N = 8, age: 21.3 ± 0.2 years) or a simulated TKD competition group (STC; N = 8, age: 21.6 ± 0.5 years). Both groups performed either simulated kicking or TKD competitions in the same time-course order, and all physiological parameters and blood sampling time-points were identical between groups. The heart rate (HR) and rating of perceived exertion (RPE) were recorded during each match-simulated kicking and TKD competition session. Blood samples were obtained before competition (Pre-Comp.), after competition—in ths case meaning four consecutive matches (End-Comp.), and 24 h after the first match (Next day) for determination of biomarkers of muscle damage (myoglobin and CK), hematological profiles, and hormonal profiles (testosterone and cortisol).Results: The responses of HR, RPE, and blood lactate levels during the consecutive testing sessions showed no differences between TMSK and STC. The changes in CK and myoglobin were greater in STC (p < 0.05), and a greater decrease in red blood cell (RBC) loss was observed in the STC group (p < 0.05). Compared with TMSK, the inflammatory state, reflected by the ratios of neutrophils-to-lymphocyte (NLR) and platelets-to-lymphocyte (PLR), was higher in STC (p < 0.05). Moreover, the catabolic state (cortisol/testosterone) was greater in STC than in TMSK (p < 0.05).Conclusion: We demonstrated that, compared with TMSK, the STC produced greater muscle damage, inflammatory responses, and catabolic stress in the Olympic competition time frame in elite male TKD athletes. Although TMSK is capable of eliciting similar physiological challenges as TKD competition, the muscle damage and hormonal profiles provoked by TMSK were not comparable to TKD competition. Our findings provide science-based data and better understanding for coaches, athletes, and sports scientists to develop TKD-specific training programs for Olympic preparation.

Aerobic Endurance is Reduced Immediately after Repeated 6‐hr Normoxic and Hyperoxic Dives at 1.35 ATA and Remains Reduced in the Hyperoxic Group 3 Days after the Last Dive

Previous measures of aerobic endurance after repeated dives on air and 100% oxygen have shown reductions in performance 24‐hr after surfacing for the hyperoxic group only. The purpose of this study was to determine aerobic endurance immediately after completing repeated (5 consecutive 6‐hr dives with 18‐hr surface intervals; dive week, DW) air and oxygen resting dives and to determine performance recovery 3 days after diving. 15 and 13 healthy men completed the air phase and 100% oxygen phase, respectively (Air/Oxygen: 29±1/31±2 yrs; VO2MAX: 55±3/53±3 ml/kg/min; mean±SD) at 1.35 atmospheres absolute (ATA). Pre‐dive base line measurements of endurance time at 85% of VO2MAX and associated physiological variables were performed a few days prior to the first dive (BL), with post‐dive (PD) and 3‐day post (PD3) recovery endurance measurements performed within two hours of surfacing and 3 days after the fifth dive of the DW. Change in plasma volume (PV) from BL was calculated from changes in hemoglobin and hematocrit (Dill‐Costill equation), both measured before exercise. Heart rate (HR), cardiac output (Q), blood lactate, and Rating of Perceived Exertion (RPE) were measured throughout the run at 85% VO2MAX: during the 5‐min walking warmup,3‐min level run, and every three min during the run at 10% grade untilex haustion. Stroke volume (SV) was calculated as Q/HR. PD PV was consistently reduced compared to BL for both phases (Air: Δ= −10.7%; Oxygen: Δ= −10.7%;p&lt;0.05), but returned to BL levels in both groups by PD3. PD aerobicendurance significantly decreased in comparison to BL for both the Air and Oxygenphases (Air: Δ= −34%; Oxygen: Δ= −36%; p&lt;0.05). Aerobic endurance recoveredfully by PD3 in the Air phase (Δ= −11.9%; p&gt;0.05), but remained reduced in the Oxygen phase (Δ= −31%; p&lt;0.05). Comparison of physiological variables at the run time matching the last data point (exhaustion) for the shortest of the three runs showed that PD HR was significantly higher than at BL for the Air phase as well as compared to Oxygen PD HR (Air PD&gt;BL: Δ= +7%, Air&gt;Oxygen: Δ= +5%; p&lt;0.05). For both groups, PD Q and SV were lower than at BL (Air Q: Δ= −19%, SV: Δ= −25%;Oxygen: Q: Δ= −12%, SV: Δ= −13%; p&lt;0.05), with Air phase Q at PD3 remaining significantly higher than Oxygen (Air&gt;Oxygen: Δ= +20%; p&lt;0.05). PD RPE was higher than BL for both groups (Air: Δ= +13%; Oxygen: Δ= +16%; p&lt;0.05) but remained elevated only for the oxygen group at PD3 (Oxygen: Δ= +19%; p&lt;0.05). Lactate for match time analysis increased in only the oxygen phase PD (Oxygen: Δ=+19%; p&lt;0.05). Previous work has shown that hyperoxia alters vascularfunction and cardiac and baroreflex regulation during exposure. These results demonstrate that some effects of hyperoxic dives persist for up to three days after diving, as indicated by reduced aerobic endurance as well as blunted HR response and suppressed Q compared to the Air group. Although peak HR obtained at exhaustionobtained in the Oxygen group did not change across days, increased lactate and RPE levels after Oxygen dives suggest that subjects were working harder after diving than before to maintain the same workload, despite the return of PV to BL levels. More work is needed to determine the mechanisms of these hyperoxia‐related reductions in performance.Support or Funding InformationOffice of Naval Research (ONR) Award Number N000141612112 and NAVSEA DSBDP N0002416WX02277.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Ratings of Perceived Exertion During Acute Resistance Exercise Performed at Imposed and Self-Selected Loads in Recreationally Trained Women

Cotter, JA, Garver, MJ, Dinyer, TK, Fairman, CM, and Focht, BC. Ratings of perceived exertion during acute resistance exercise performed at imposed and self-selected loads in recreationally trained women. J Strength Cond Res 31(8): 2313-2318, 2017-Resistance exercise (RE) is commonly used to elicit skeletal muscle adaptation. Relative intensity of a training load links closely with the outcomes of regular RE. This study examined the rating of perceived exertion (RPE) responses to acute bouts of RE using imposed (40% and 70% of 1 repetition maximum [1RM]) and self-selected (SS) loads in recreationally trained women. Twenty physically active women (23.15 ± 2.92 years), who reported regular RE training of at least 3 weekly sessions for the past year, volunteered to participate. During the initial visit, participants completed 1RM testing on 4 exercises in the following order: leg extension, chest press, leg curl, and lat pull-down. On subsequent visits, the same exercises were completed at the SS or imposed loads. The RPE was assessed after the completion of each set of exercises during the 3 RE conditions using the Borg-15 category scale. Self-selected loads corresponded to an average of approximately 57%1RM (±7.62). Overall, RPE increased with load (40%1RM = 11.26 [±1.95]; SS 57%1RM = 13.94 [±1.58]; and, 70%1RM = 15.52 [±2.05]). Reflecting the linear pattern found between load and perceived effort, the present data provide evidence that RPE levels less than 15 likely equate to loads which are not consistent with contemporary American College of Sports Medicine (ACSM) guidelines for enhancing musculoskeletal health which includes strength and hypertrophy. Women desiring increases in strength and lean mass likely need to train at an exertion level at or surpassing a rating of 15 on the Borg-15 category. This article examined the modification of training load on perceived exertion, but other variables, such as the number of repetitions completed, may also be targeted to achieve a desired RPE. The primary understanding is that women who engage in RE may not self-select loads that are consistent with the ACSM recommendations for musculoskeletal health.

Endurance Exercise in Hypoxia, Hyperoxia and Normoxia: Mitochondrial and Global Adaptations.

We hypothesized short-term endurance exercise (EN) in hypoxia (HY) to exert decreased mitochondrial adaptation, peak oxygen consumption (VO2peak) and peak power output (PPO) compared to EN in normoxia (NOR) and hyperoxia (PER). 11 male subjects performed repeated unipedal cycling EN in HY, PER, and NOR over 4 weeks in a cross-over design. VO2peak, PPO, rate of perceived exertion (RPE) and blood lactate (Bla) were determined pre- and post-intervention to assess physiological demands and adaptation. Skeletal muscle biopsies were collected to determine molecular mitochondrial signaling and adaptation. Despite reduced exercise intensity (P<0.05), increased Bla and RPE levels in HY revealed higher metabolic load compared to PER (P<0.05) and NOR (n.s.). PPO increased in all groups (P<0.05) while VO2peak and mitochondrial signaling were unchanged (P>0.05). Electron transport chain complexes tended to increase in all groups with the highest increase in HY (n.s.). EN-induced mitochondrial adaptability and exercise capacity neither decreased significantly in HY nor increased in PER compared to NOR. Despite decreased exercise intensity, short term EN under HY may not necessarily impair mitochondrial adaptation and exercise capacity while PER does not augment adaptation. HY might strengthen adaptive responses under circumstances when absolute training intensity has to be reduced.

Predicting time to exhaustion during high-intensity exercise using rating of perceived exertion

Summary Objectives This study aimed to predict the time to exhaustion (Tlim) at different high-intensity exercises using a linear regression between 14–17 points of Borg scale and their respective time, verify the agreement and compare them to the real Tlim. Methods Nineteen healthy male subjects undertook four constant-load exhaustive exercise bouts on cycle ergometer. These tests were performed on different days and with four different intensities. The power output imposed in each test was determined based on familiarization trials in order to induce a subjects’ exhaustion between 2 and 15 min. They were also asked to report the rating of perceived exertion (RPE) during these constant-load exercise bouts. The first value was freely chosen as soon as the subject felt able to accurately report RPE levels, the number corresponding to the verbal anchor on the Borg scale, within of first minute of exercise. Thereafter, whenever they felt that the RPE was increased, the value was recorded. A linear regression was fitted plotting the 14–17 RPE range as a function of time of each test. The Tlim was estimated by extrapolation of the linear relationship to the RPE 19 (Tlim19) and 20 (Tlim20). Results The measured Tlim values were significantly higher at the Tlim19 at 230 ± 33 W, 256 ± 33 W and 289 ± 36 W ( P P > 0.05). Furthermore, the intraclass correlation coefficients were all strong (ICC = 0.79–0.87). The RPE at same percentages of Tlim (25, 50, 75 and 100%) during the four constant-load exercise bouts were not different ( P > 0.05). Conclusion Tlim during high-intensity exercises can be accurately predicted by the use of RPE values in the 14–17 range assuming that exhaustion occurs at RPE = 20.

Determining target heart rate for exercising in a cardiac rehabilitation program: a retrospective study.

One of the well-established methods used to determine endurance training intensity for patients in outpatient cardiac rehabilitation (CR) is to take a percentage (70%-85%) of the maximal or peak heart rate (HRmax) from a recent postevent symptom-limited graded exercise test (GXT). Because many patients are referred to CR without having had a maximal GXT, a current practice is to use 30% to 50% above resting heart rate (RHR) to estimate endurance training intensity. The purpose of this study was to determine if a target heart rate (THR) of 30% to 50% above RHR approximated a THR of 70% to 85% of the HRmax achieved on GXT (HRmax GXT) and provided equivalent exercise intensity based on ratings of perceived exertion (RPE) and metabolic equivalency thresholds (METs). A retrospective chart review of 53 patients enrolled in CR and had documentation of postevent GXT was conducted to determine the patient's mean exercise heart rate (HR) achieved at each session to percentage above RHR and percentage HRmax GXT. Analysis was conducted to determine and compare patients' HRs, RPE, and MET levels when patients were exercising within the THR ranges of 30% to 50% above RHR and 70% to 85% HRmax GXT. A THR range of 30% to 50% above RHR approximated 60% to 70% HRmax GXT. Mean exercise HRs progressed from 39% to 49% above RHR sessions 2 to 6 with mean (SD) RPE of 10.58 (0.55) to 11.44 (0.68) on the Borg scale and mean (SD) MET level of 2.91 (0.55) to 3.31 (0.6). Mean exercise HRs progressed to 54% to 65% above RHR sessions 7 to 18 and approximated 70% to 73% HRmax GXT. Mean (SD) RPE at this intensity ranged from 11.57 (0.58) to 12.21 (0.53) with a mean (SD) MET level of 3.47 (0.6) to 3.8 (0.77). In the observed population, a THR of 30% to 50% above RHR underestimated the THR range of 70% to 85% HRmax GXT but provided adequate exercise intensity for patients at the beginning of a CR program based on percentage HRmax GXT, RPE and MET levels.

Comparison between Preexercise Meals Intake Effect with Different Glycemic Load on Exercise Performance in Female Athletes

Athletes usually search for strategies to optimize their performance. Manipulation of carbohydrate (CHO) resources glycemic load in order to optimizing athletic performance provides new research areas in nutritional sport. Purpose of this study is to examine the effects of two isocaloric meals with different glycemic load (GL) on exercise performance and serum free fatty acids. Thirty six non-professional athletic women with ages between 19 and 24 were assigned in a double blinded randomized clinical trial with two period cross-over design. Participants in each group received a high or low GL meal as a breakfast, and 7-day wash out period is determined. serum free fatty acid (FFA) measurements were performed before and after each phase of intervention.3 hour After ingestion of a meal, participants run to exhaustion, in a 20 meters shuttle run pacer. Time to exhaustion (TTE) was recorded as a measure of exercise performance. In an attempt to ensure that subjects run to exhaustion, rating of perceived exertion (RPE) was measured, using a Borg scale, too. The ingestion of a low GL or high GL pre-exercise meal did not lead to different TEE and RPE at 3 hours before exercise in female athletic students. Mean changes of serum FFA were higher in low GL than high GL meal. Consumption of a low GL meal compared with a high GL meal at 3-hr before a shuttle run pacer, was not associated with significant changes in TEE and RPE levels but low GL meal led to more increase serum FFA than high GL.

Quantification of Perceived Exertion During Isometric Force Production With the Borg Scale in Healthy Individuals and Patients With Chronic Stroke

Background: The Borg Rating of Perceived Exertion (RPE) scale is widely used for many patient populations, but the ability of patients to accurately report their RPE without visual feedback has not been studied. Objective: The objective was to determine whether the Borg scale could be used as a measure of perceived isometric exertion in healthy subjects and patients with stroke. Methods: In experiment 1, young healthy subjects (n = 15) were instructed to perform spontaneous pushes (ie, self-selected effort) without visual feedback and to produce and hold self-determined isometric finger flexion at 5 Borg levels without visual feedback. In experiment 2, subjects with chronic stroke (n = 10) were instructed to produce self-determined isometric elbow flexion at 4 perceptual levels on the impaired and nonimpaired sides. Results: In experiment 1, young healthy subjects, asked to self-select without visual feedback (spontaneous push), tended to exert at a “somewhat hard” level, about 12% of maximal voluntary contraction (MVC). Self-selection of forces ranged from 2% of MVC (ie, very light) to 39% of MVC (ie, very hard). In experiment 2, subjects with stroke were able to distinguish different levels of perceived exertion among light (19% MVC), somewhat hard (33% MVC), and hard (63% MVC) levels; this ability was not different for the impaired and nonimpaired limbs. Conclusion: Both healthy subjects and subjects with stroke are able to differentiate distinct levels of perceived exertion during isometric force when prompted with the Borg scale. Efforts at lower percentages of MVC are perceived by subjects with stroke as greater-than-normal Borg RPE levels.