Kristen M. Lagally

Perceived exertion, electromyography, and blood lactate during acute bouts of resistance exercise.

PURPOSE This study examined ratings of perceived exertion (RPE) during resistance exercise in women. In addition, changes in blood lactic acid and biceps muscle activity assessed using electromyography (EMG) were investigated as potential mediators of RPE during resistance exercise. METHODS Twenty female volunteers (age, 25 +/- 4 yr) performed one set of biceps curl exercise at 30%, 60%, and 90% of their one-repetition maximum (1-RM). Total work was held constant by varying the number of repetitions during each of the three intensities. The three intensities were performed in random order. RPE responses were assessed for both the active muscle (RPE-AM) and the overall body (RPE-O) following each intensity. EMG data were collected from the biceps brachii muscle during each intensity. Blood samples were taken before and following the intensities and analyzed for blood lactic acid concentration. RESULTS A two-factor repeated-measures ANOVA showed a significant RPE (region) x intensity interaction (P < 0.02). Both RPE-AM and RPE-O increased as the intensity of exercise increased. EMG activity increased significantly (P < 0.01) as the intensity of exercise increased. A two-factor repeated measures ANOVA performed on the blood lactate data showed a significant (P < 0.04) time x intensity interaction. Postexercise [Hla] was significantly greater (P < 0.01) at 90% 1-RM than at 30% 1-RM. No significant differences were found in [Hla] between 30% and 60% 1-RM, or between 60% and 90% 1-RM. CONCLUSION These results indicate that monitoring RPE may be a useful technique for regulating resistance exercise intensity. Moreover, blood lactate and activity of the involved muscle may mediate the relation between RPE and resistance exercise intensity.

Construct validity of the OMNI resistance exercise scale.

This study examined the construct validity of the Adult OMNI Perceived Exertion Scale for Resistance Exercise (OMNI-RES). Forty (20 men and 20 women) subjects performed 1 repetition of the knee extension exercise at 40, 50, 60, 70, 80, and 90% of the 1 repetition maximum. Active muscle and overall body ratings of perceived exertion (RPE) were collected from the Borg 15-category RPE scale and the OMNI-RES immediately following each repetition. Construct validity was established by correlating RPE from the OMNI-RES with RPE from the Borg RPE scale using regression analysis. The results indicated a positive and linear relationship between RPE from the OMNI-RES and RPE from the Borg scale for both men and women. Validity coefficients ranged from r = 0.94 to 0.97. The high level of construct validity indicates that the OMNI-RES measures the same properties of exertion as the Borg RPE scale during resistance exercise and suggests that the 2 scales can be used interchangeably during resistance exercise.

The accuracy of the TriTrac-R3D accelerometer to estimate energy expenditure.

PURPOSE This study examined the reliability and validity of the TriTrac-R3D triaxial accelerometer to estimate energy expenditure during various modes of exercise. METHODS Twenty subjects (age = 21.5+/-3.4 yr; body mass index = 23.3+/-3.6 kg x m(-2)) performed five exercises (treadmill walking, treadmill running, stepping, stationary cycling, and slideboard), with each lasting 20-30 min and workload increased at 10-min intervals. To test the inter-TriTrac reliability, two TriTrac-R3D accelerometers were worn during each exercise period, and to examine validity, a simultaneous measurement of energy expenditure was made using indirect calorimetry (SensorMedics 2900 Metabolic Cart). RESULTS Results showed a significant correlation between the two TriTrac-R3D accelerometers during all exercises. The difference in estimated energy expenditure between the two accelerometers during the walking, stepping, and slideboard exercises was less than 1 kcal x min(-1) but statistically significant (P<0.05). There was also a significant correlation between energy expenditure estimated by each of the TriTrac-R3D accelerometers and indirect calorimetry during walking, running, stepping, and slideboard exercise (P<0.05). The interaction of Method x Workload was significant (P<0.05) for each exercise, indicating that the TriTrac-R3D underestimates energy expenditure and that the magnitude of this underestimation increases as workload increases. CONCLUSIONS Therefore, energy expenditure estimated via triaxial accelerometry does not increase with increasing workloads. These results suggest that there are limitations to using triaxial accelerometry to quantify energy expenditure.

Ratings of perceived exertion and muscle activity during the bench press exercise in recreational and novice lifters.

This study examined ratings of perceived exertion (RPE) and electro-myography (EMG) during resistance exercise in recreational and novice lifters. Fourteen novice (age = 21.5 ± 1.5 years) and 14 recreationally trained (age = 21.9 ± 2.2 years) women volunteered to perform the bench press exercise at 60 and 80% of their 1 repetition maximum (1RM). RPE and EMG were measured during both intensities. Statistical analyses revealed that active muscle RPE increased as resistance exercise intensity increased from 60% 1RM to 80% 1RM (12.32 ± 1.81 vs. 15.14 ± 1.74). Integrated EMG also increased as resistance exercise intensity increased from 60% 1RM to 80% 1RM (in the pectoralis major; 98.62 ± 17.54 vs. 127.98 ± 29.02). No significant differences in RPE or EMG were found between novice and recreational lifters. These results indicate that RPE is related to the relative exercise intensity lifted as well as muscle activity during resistance exercise for both recreational and novice lifters. These results support the use of RPE as a method of resistance exercise intensity estimation for both types of lifters.

Ratings of perceived exertion during low- and high-intensity resistance exercise by young adults

Ratings of perceived exertion (RPE) are commonly used to monitor the intensity of aerobic exercise. Whether ratings of perceived exertion can be used similarly during resistance exercise is unclear. To examine this question, perceived exertion was measured at 30% and 90% of the one-repetition maximum (1-RM), while holding work constant between intensities. Ratings for the active muscles and for the overall body were examined during both intensities. 10 male (age = 23.2 ± 3.6 yr.) and nine female (age = 21.8 ± 2.7 yr.) volunteers underwent a one-repetition maximum procedure for each of the following exercises; bench press, leg press, latissimus pull down, triceps press, biceps curl, shoulder press, and calf raise. All subjects then completed two experimental trials on separate days. The high-intensity trial consisted of one set of five repetitions at 90% of the one-repetition maximum. The low-intensity trial consisted of one set of 15 repetitions at 30% of the one-repetition maximum. Active muscle and overall body ratings of perceived exertion were obtained immediately at termination of each of the seven exercises at both intensities. A two-factor (RPE x Intensity) repeated-measures analysis of variance was performed separately for each exercise. Both active muscle and overall body ratings of perceived exertion were higher (p<.01) for the high-intensity trial than for the low intensity trial. Active muscle ratings were higher (p<.01) than overall body ratings for all exercises. Ratings of perceived exertion during resistance exercise are related to intensity of the resistance exercise (percentage of the one-repetition maximum). This information suggests that ratings of perceived exertion can provide information regarding the intensity of resistance exercise. Furthermore, sensations of exertion in the active muscles during resistance exercise are greater than sensations for the overall body.

Self-regulated cycling using the children's OMNI Scale of Perceived Exertion

PURPOSE An estimation and production paradigm was used to determine whether clinically normal 8- to 12-yr-old female (N = 18) and male (N = 18) children could (a) self-regulate intermittent cycle ergometer exercise using a prescribed target rating of perceived exertion (RPE), (b) discriminate between target RPEs, and (c) produce intermittent target RPEs in both an ascending and descending sequence. METHODS Overall body RPE was assessed with the Childrens OMNI Scale (0-10). Subjects underwent (a) one orientation trial, (b) one estimation (E) trial, and (c) two production (P) trials. During E, RPE was estimated each minute of a progressive cycle ergometer test. During the 3-min intermittent P trials, subjects titrated cycle brake force to produce either an RPE sequence of 2 and 6 (ascending) or 6 and 2 (descending). The P trials simulated short, intermittent exercise typical of childrens play. RESULTS Oxygen uptake (VO2) did not differ between E and P at a target RPE of 2 (0.63 versus 0.66 L x min(-1)) and 6 (1.27 vs 1.21 L x min(-1)). Heart rate (HR) did not differ between E and P at a target RPE of 2 (104.1 vs 102.6 beats.min-1) and 6 (153.7 vs 154.5 beats x min(-1)). Both VO2 and HR were higher (P < 0.01) at a target RPE-6 than -2. Responses were not affected by gender or production sequence. CONCLUSION Young female and male children were able to use the OMNI Scale to self-regulate short-duration intermittent cycle exercise intensity.

Strength tracking using the OMNI resistance exercise scale in older men and women.

Gearhart, RF Jr, Lagally, KM, Riechman, SE, Andrews, RD, and Robertson, RJ. Strength tracking using the OMNI resistance exercise scale in older men and women. J Strength Cond Res 23(3): 1011-1015, 2009-Strength tracking uses ratings of perceived exertion (RPE) as a reference value to determine changes in strength as a function of a resistance training program. The purpose of this investigation was to determine if the OMNI Resistance Exercise Scale (OMNI-RES) could be used to track training-induced strength changes in older adults. Twenty-two men (64.3 + 3.2 years) and 27 women (63.8 + 2.8 years) volunteered to participate. Subjects underwent a maximal lifting test, during which they estimated perceived exertion before and following 12 weeks of resistance exercise training. Leg press (LP), latissimus dorsi pull-down (LA), chest press (CP), leg extension (LE), leg curl (LC), arm extension (AE), and arm curl (AC) were performed. Paired samples t-tests were used to compare resistance lifted pre- and post-training at each criterion RPE (4, 6, and 8). One repetition maximum increased from pretraining to post-training (p < 0.05) for all exercises. The resistance lifted at each criterion RPE also increased (p < 0.05) during the 12-week training session for every exercise. Older adults lifted more weight at 3 criterion RPEs as their strength increased, providing an RPE-based procedure to track strength training changes using the OMNI-RES. As such, it seems that RPE from the OMNI-RES can be used to track strength in older adults.

The Validity of Using Prior Ratings of Perceived Exertion to Regulate Resistance Exercise Intensity

This investigation examined the validity of using ratings of perceived exertion (RPE) to regulate intensity during resistance exercise. 19 male (M age = 22.2 yr., SD = 2.7) and 19 female (M age = 21.4 yr., SD = 2.3) participants estimated exertion when performing the knee extension at 40% to 90% of one-repetition maximum. One week later, participants were asked to produce weights for the knee extension that elicited the feelings of exertion associated with 9, 13, and 17 on the Borg RPE scale. The weight produced at 9, 13, and 17 during the production session was compared to the weight lifted at each RPE during the estimation session. The effect sizes associated with the differences in weight lifted across sessions at each RPE were generally small in magnitude, especially at the higher intensities (ES = .40, –.09, .15, respectively). The results of this investigation support the use of RPE as a method of prescribing the intensity of resistance exercise.

Physiologic and metabolic responses to a continuous functional resistance exercise workout.

Lagally, KM, Cordero, J, Good, J, Brown, DD, and McCaw, ST. Physiologic and metabolic responses to a continuous functional resistance exercise workout. J Strength Cond Res 23(2): 373-379, 2009-The purpose of this study was to evaluate the physiologic and perceptual responses to a continuous functional exercise workout. Ten men and 10 women (21.2 ± 2.4 and 21.0 ± 1.5 years) completed a maximal oxygen uptake test, strength test, and body composition analysis. Subjects then participated in 3 familiarization sessions, during which they followed a videotaped routine that consisted of a series of functional resistance exercises performed in a continuous manner. Subjects performed the same routine in a final session, during which &OV0312;O2, &OV0312;co2, respiratory exchange ratio (RER), RPE, and heart rate were measured and blood samples were taken and analyzed for blood lactic acid concentration. Descriptive statistics were calculated for RPE, RER, blood lactic acid concentration, energy expenditure, and absolute and relative oxygen uptake and heart rate. Energy expenditure was calculated using &OV0312;O2 and RER. Independent t-tests were used to examine differences between men and women for oxygen consumption, weight lifted, and energy expenditure during the workout. Subjects had a mean &OV0312;o2 of 27.8 ml·kg−1·min−1 (51% of &OV0312;o2 peak and 47.8% of &OV0312;o2 reserve), a mean heart rate of 156 bpm (83% of maximum heart rate), and a mean RER of 0.91. The mean RPE was 5.9, and the mean difference between pre and post lactic acid concentration was 2.5 mmol·L−1. The mean total caloric expenditure was 289 kcal. Men lifted significantly heavier weights and expended more total calories than women. Caloric expenditure (kcal·kg−1·min−1), &OV0312;o2, and weight lifted were similar between men and women when expressed relatively. Performing dynamic functional exercises in a continuous manner resulted in energy expenditure values, but not relative &OV0312;o2 values, that meet the American College of Sports Medicine recommendations.

Anchoring Procedures in Reliability of Ratings of Perceived Exertion during Resistance Exercise

Although the validity of perceived exertion as a method of monitoring the intensity of resistance exercise has been established, little is known about the test-retest reliability of ratings of perceived exertion during resistance exercise. Specifically, it is unknown whether the use of different anchoring procedures influences the reliability of ratings of perceived exertion. 30 men were assigned to an Exercise, Memory, or combined Exercise and Memory anchoring group. Participants completed an assessment of maximal leg-extension strength and were introduced to the Borg 15-category rating of perceived exertion scale through anchoring procedures that varied across groups. During two sessions of resistance exercise, participants rated active muscle perceived exertion after performing one repetition of the leg-extension exercise at 40%, 50%, 60%, 70%, 80% and 90% of the one-repetition maximum. A three-factor (Group × Intensity × Session) analysis of variance was performed to examine the perceived exertion data. Perceived exertion increased significantly (p < .01) with increasing exercise intensity in all groups and in both sessions. Mean ratings did not differ significantly among groups. Reliability was assessed for each group. Intraclass correlation coefficients ranged from .07 to .80 and percent agreement ranged from 60% to 90%. The results indicate that the reliability of ratings of perceived exertion during resistance exercise is acceptable regardless of the type of anchoring procedures used.