Psychological Responses to High-Intensity Interval Training: A Comparison of Graded Walking and Ungraded Running at Equivalent Metabolic Loads.

High-intensity interval training (HIIT) is highly beneficial for health and fitness and is well tolerated. Treadmill-based HIIT normally includes running interspersed with walking. The purpose of this study was to compare ungraded running and graded walking HIIT on perceived exertion, affective valence, and enjoyment. Thirty-four active, healthy adults completed maximal testing and two 20-min HIIT trials alternating between 85% of VO2peak and a comfortable walking speed. Affective valence, enjoyment, and perceived exertion, both overall (ratings of perceived exertion [RPE]-O) and legs only (RPE-L), were measured. RPE-O and affective valence were similar between HIIT trials (p > .05), RPE-L was higher for walk HIIT (p < .05), and enjoyment was higher for run HIIT (p < .05). Findings indicate that both walk and run HIIT produce exertion, affective, and enjoyment responses that are positive and possibly supportive of exercise behavior. Walk HIIT may be desirable for individuals who are unable or do not want to run.

Comparison of Powerlifting Performance in Trained Men Using Traditional and Flexible Daily Undulating Periodization.

Colquhoun, RJ, Gai, CM, Walters, J, Brannon, AR, Kilpatrick, MW, D'Agostino, DP, and Campbell, WI. Comparison of powerlifting performance in trained men using traditional and flexible daily undulating periodization. J Strength Cond Res 31(2): 283-291, 2017-Daily undulating periodization (DUP) is a growing trend, both in practice and in the scientific literature. A new form of DUP, flexible daily undulating periodization (FDUP), allows for athletes to have some autonomy by choosing the order of their training. The purpose of this study was to compare an FDUP model to a traditional model of DUP on powerlifting performance in resistance-trained men. Twenty-five resistance-trained men were randomly assigned to one of 2 groups: FDUP (N = 14) or DUP (N = 11). All participants possessed a minimum of 6 months of resistance training experience and were required to squat, bench press, and deadlift 125, 100, and 150% of their body mass, respectively. Dependent variables assessed at baseline and after the 9-week training program included bench press 1 repetition maximum (1RM), squat 1RM, deadlift 1RM, powerlifting total, Wilks Coefficient, fat mass, and fat-free mass (FFM). Dependent variables assessed during each individual training session were motivation to train, Session Rating of Perceived Exertion (Session RPE), and satisfaction with training session. After the 9-week training program, no significant differences in intensity or volume were found between groups. Both groups significantly improved bench press 1RM (FDUP: +6.5 kg; DUP: +8.8 kg), squat 1RM (FDUP: +15.6 kg; DUP: +18.0 kg), deadlift 1RM (FDUP: +14.8 kg; DUP: +13.6 kg), powerlifting total (FDUP: +36.8 kg; DUP: +40.4 kg), and Wilks Coefficient (FDUP: +24.8; DUP: +26.0) over the course of study (p = <0.001 for each variable). There was also a significant increase in FFM (FDUP: +0.8 kg; DUP: +0.8 kg) for both groups (p = 0.003). There were no differences in motivation to train, session RPE, or satisfaction with training session measurements between groups (p = 0.369-0.702, respectively). In conclusion, FDUP seems to offer similar resistance training adaptations when compared with a traditional DUP in resistance-trained men.

Affective and Enjoyment Responses to High-Intensity Interval Training in Overweight-to-Obese and Insufficiently Active Adults.

High-intensity interval training (HIIT) has many known physiological benefits, but research investigating the psychological aspects of this training is limited. The purpose of the current study is to investigate the affective and enjoyment responses to continuous and high-intensity interval exercise sessions. Twenty overweight-to-obese, insufficiently active adults completed four counterbalanced trials: a 20-min trial of heavy continuous exercise and three 24-min HIIT trials that used 30-s, 60-s, and 120-s intervals. Affect declined during all trials (p < .05), but affect at the completion of trials was more positive in the shorter interval trials (p < .05). Enjoyment declined in the 120-s interval and heavy continuous conditions only (p < .05). Postexercise enjoyment was higher in the 60-s trial than in the 120-s trial and heavy continuous condition (p < .05). Findings suggest that pleasure and enjoyment are higher during shorter interval trials than during a longer interval or heavy continuous exercise.

Exertional responses to sprint interval training: a comparison of 30-sec. and 60-sec. conditions.

The purpose of this study was to assess the effect of sprint interval training on rating of perceived exertion. 20 healthy participants (11 men, 9 women; M age = 23 yr.) completed a maximal cycle ergometer test and two high-intensity interval training cycling sessions. Each session utilized the same work-to-rest ratio (1:1), work intensity (90% max), recovery intensity (10% work intensity), and session duration (16 min.). Trials differed on duration of the interval segment, with a 30-sec. trial and a 60-sec. trial. Sessions required the same amount of total work over the duration of the trial. Rating of perceived exertion assessed before, during, and after exercise were higher for the 60-sec. trial than the 30-sec. trial despite no difference in total work. High intensity interval training trials utilizing the same total external work but differing in interval length produced different ratings of perceived exertion. Perceived exertion is significantly higher for sessions of exercise that utilize longer work intervals. These findings suggest that shorter intervals may produce more favorable exertional responses that could positively affect future behavior.

Psychophysiological Responses to High-Intensity Interval Training Exercise over Menstrual Cycle Phases: An Exploratory Study.

INTRODUCTION: Although there is potential for the menstrual cycle to impact psychophysiological responses to exercise, there has been a paucity of studies investigating this aspect, specifically in the context of high-intensity interval training (HIIT). PURPOSE: This exploratory study aimed to examine the psychophysiological responses to HIIT over the menstrual cycle. METHODS: Twenty-three healthy and physically active young women were recruited. Each woman completed a cycle ergometer HIIT session in the menstrual, follicular, and luteal phases of the menstrual cycle in a random order. Psychophysiological variables of interest were collected at baseline, and during and after exercise. Primary variables of interest were anxiety, mood, motivation, enjoyment, arousal, affect, and menstrual distress. RESULTS: Higher pain, water retention, behavior change (related to social interactions, eating habits, and self-performance), and autonomic reactions (consisting of nausea, dizziness, hot flashes, and cold sweats) were observed before HIIT during the menstrual phase compared with the follicular phase ( P < 0.05). Participants exhibited worse psychological responses to HIIT sessions during the menstrual phase, followed by the luteal phase. Findings also noted participants arrived to the laboratory with lower motivation to initiate HIIT sessions during the luteal and menstrual phases compared with the follicular phase. This difference was observed before and during HIIT. Motivation and depressive symptoms showed a significant reduction from pre-HIIT to post-HIIT ( P < 0.05), regardless of menstrual phase. CONCLUSIONS: The findings revealed that the menstrual cycle had a significant impact on psychophysiological responses. Moreover, HIIT could be adopted to improve motivation and depressive symptoms; however, further research is needed to explore the effects of HIIT across the menstrual cycle in women with clinical depression.

Examining the effects of increasing then decreasing exercise intensity within a session of aerobic exercise.

Recent studies have examined the relations between the slope of pleasure experienced during exercise and remembered pleasure, forecasted pleasure, and enjoyment. OBJECTIVES: This study advances this line of research by examining the effects of exposing participants to exercise that increases in intensity and then decreases in intensity. METHODS: In a within-subjects design, participants completed three exercise sessions matched for total and average work. One session steadily increased in intensity, another steadily decreased in intensity, and a third increased-then-decreased in intensity. Remembered pleasure, forecasted pleasure, and exercise enjoyment served as primary outcome variables. RESULTS: Remembered pleasure, forecasted pleasure, and enjoyment did not differ between conditions. Remembered pleasure was positively associated with mean experienced pleasure, the overall slope of pleasure during the exercise session, affect experienced at the end of exercise, forecasted pleasure, accomplishment, and enjoyment. CONCLUSIONS: These data add to a growing literature on the effects of patterns of exercise intensity on affective responses to exercise. The results are discussed in context of previous and more recent research.

Effect of Menstrual Cycle Phase on Perceived Exertion During Aerobic Exercise in Eumenorrheic Women: A Systematic Review and Meta-analysis.

Background: The rating of perceived exertion (RPE) is a readily available and practical tool widely used in exercise science to monitor exercise load, but a rigorous review of the effect of menstrual cycle (MC) phases on RPE within continuous aerobic exercise has not yet been completed. Objective: This study investigated the effects of the MC phase on RPE during aerobic exercise. Study Design: This was a systematic review and meta-analysis. Methods: The search strategy was carried out using the 5 most common scientific databases. While qualitative analyses were performed in all included studies, random effects to standard mean difference were calculated and meta-analysis was performed where possible. This study addresses comparison for RPE at the beginning, middle, and end of the exercise adopting 2 mains analysis. The first adopted early cycle (first session of the cycle) as control compared with the subsequent phases, and the second adopted days 1 to 5 (early follicular) as control compared with the subsequent phases. Results: A total of 17 studies (n = 160) were included in the qualitative synthesis. The meta-analysis showed that MC phases did not impact RPE (P > .05). Conclusions: The current meta-analysis showed that MC does not impact RPE. Although acute RPE is not impacted by MC phases, future studies and practitioners should pay attention to the impact of RPE session by session throughout the MC.

Psychophysiological Responses to Self-Selected Exercise Intensity Over the Menstrual Cycle: A Randomized Crossover Phase Trial.

Purpose: This study investigated the psychophysiological responses during self-selected exercise intensity over the course of the menstrual cycle (MC). Methods: Seventeen healthy women with regular MCs completed three randomized treadmill bouts of 30 min of self-selected exercise intensity during menstruation, mid-follicular, and late luteal phases. Anxiety, menstrual distress (i.e., pain, behavior change, autonomic reaction, fluid retention, and negative affect) and profile of mood (i.e., tension, depression, and anger) were measured before exercise. Arousal, heart rate (HR), motivation, rating of perceived exertion and affective valence were measured before, during and after each exercise session. Results: Anger, anxiety, behavior change, pain, and negative affect were significantly greater (p < .05) during menstruation compared to the mid-follicular phase, whereas fluid retention, anger, behavior change, and autonomic reaction were greater (p < .05) during the late luteal phase compared with the mid-follicular phase. Participants felt more negative affective valence and less motivation to start exercise during menstruation compared with other MC phases. Average treadmill speed (5.8 ± 1.1 vs 6.0 ± 0.7 vs 5.9 ± 0.7 km/h-1, p = .36) and %HRmax (74.9 ± 3.2 vs 77.8 ± 5.4 vs 77.4 ± 7.1%, p = .40) did not differ between menstruation, mid-follicular, and late luteal phases. Also, noteworthy is that participants self-selected an intensity that exceeded the minimum levels recommended for health and cardiorespiratory fitness promotion (64-70% HRmax). Conclusions: Results of this study indicate that psychophysiological responses are negatively impacted mainly during menstruation and the late luteal phase of the MC. These findings may be helpful for professionals who work to promote the initiation and maintenance of exercise in women.

The effect of menstrual cycle and exercise intensity on psychological and physiological responses in healthy eumenorrheic women.

Psychological responses such as affect, mood, motivation, anxiety are important considerations for exercise adherence. A large body of evidence indicates that exercise intensity is a controllable variable capable of increasing positive feelings. Investigations thus far, however, have not considered that the higher incidence of negative psychological responses in women could be due to physiological particularities of the menstrual cycle (MC). This project investigates the effect of MC phases and exercise intensity on psychophysiological responses in fourteen healthy, eumenorrheic and physically active women. Measuring psychophysiological responses before, during and after exercise, participants completed two exercise bouts of 15 min above and below the anaerobic threshold in the follicular phase (FP) and the luteal phase (LP) of the MC. Lower levels of depression and hostility and higher levels of vigor, affect and motivation were observed during exercise in the FP. Exercise at moderate intensity elicited more positive psychological responses compared to high-intensity exercise, highlighted by findings that affect and rating of perceived exertion were worse in the LP without changes in physiological responses. These findings suggest no effect of MC on physiological responses, but psychological responses are impaired in the LP, worsening particularly during exercise at high intensity.

Patient reported physical and mental health changes associated with a comprehensive cardiovascular risk reduction program for women with breast cancer receiving potentially cardiotoxic chemotherapy.

OBJECTIVE: Women with breast cancer (BCA) and cardiovascular disease (CVD) risk factors are at increased risk of developing cardiovascular complications when exposed to potentially cardiotoxic cancer therapy. The benefit of aggressive CVD risk factor modification to reduce adverse treatment-related psychologic and biologic effects is not well established. METHODS: Using a single group pre-test, post-test design, 33 women with BCA receiving anthracycline and/or trastuzumab therapy participated in a 6-month comprehensive CVD risk reduction program involving formal cardio-oncology evaluation along with regular motivational counseling for improved nutrition and physical activity. Study parameters were assessed at baseline and 6 months with paired t-tests used to evaluate changes after the intervention. RESULTS: The mental component summary score assessed by SF-36V2 improved significantly after program completion (45.0 to 48.8, effect size 0.37, p = 0.017), however the physical component summary score declined (46.2 to 40.9, effect size - 0.53, p = 0.004). Despite this decline in perceived physical health, markers of health-related fitness and nutritional status were maintained or improved. Systolic and diastolic blood pressure also improved after the intervention (136.7 to 124.1 mmHg, p = 0.001 and 84.0 to 78.7 mmHg, p = 0.031, respectively). No significant change in resting heart rate, body mass index, lipids, hemoglobin A1C, or left ventricular ejection fraction was observed. CONCLUSIONS: Patient-reported mental health improved significantly in women with BCA enrolled in a comprehensive CVD risk reduction program despite exposure to potentially cardiotoxic therapies. This study provides preliminary data for future randomized controlled trials evaluating the effects CVD risk reduction program in high-risk breast cancer cohorts.

Load rather than contraction type influences rate of perceived exertion and pain.

The purpose of the study was to determine whether muscle contraction type (concentric [CON] or eccentric [ECC]) or loading (relative or absolute) has a greater impact on the perceptual and metabolic responses to conventional resistance exercise. Additionally, overall effort, pain sensations, and specific pain descriptors were compared with physiological responses. Seven healthy men (mean +/- SE, 25.71 +/- 2.17 years) with resistance training experience completed 2 one-repetition maximum (1-RM) trials. Subsequently, 2 randomized, counterbalanced, experimental sessions were completed consisting of 4 sets of 10 repetitions for 6 exercises. These sessions were performed at 65% CON 1-RM for CON only contractions or 65% CON 1-RM + 20% for ECC contractions. Blood samples were taken pre, post, and 15 minutes postexercise. OMNI-RPE (OMNI-Res), CR-10 pain rating, McGill pain ratings, and heart rate (HR) were recorded after each set. A significant time effect occurred for OMNI-Res, pain, lactate, and HR (p < 0.05). No significant pattern emerged for the contraction type, except for higher HR and lactate immediately postexercise for the CON contractions. Physiological measures were not significantly related to perceptual measures. When considered with previous data, muscle loading rather than contraction type plays the primary role in perceptual alterations of effort sense and pain. Practical applications of the investigation are that strength and conditioning professionals may be able to load CON and ECC contractions in a relative fashion by increasing loads in the ECC portion by 20% above the CON load that would result in comparable perceptual experiences.

The physical self-attribute questionnaire: development and initial validation.

The Physical Self-attribute Questionnaire was developed for use in conjunction with the Physical Self-perception Profile to model cognitive facets of perceived competence, certainty, importance, and discrepancy from ideal to each of the physical subdomains measured by the latter (Strength, Attractive Body, Condition, and Sport). To this end, two studies were conducted. Study 1 examined the factor structure, test-retest reliability, and validity of the questionnaire in a sample of 154 (28 men, 126 women) undergraduate health students. Reliability and validity were acceptable, and confirmatory factor analysis indicated good fit for a four-factor solution. In Study 2, the reliability, validity, and factor structure was again confirmed in a sample of 120 (83 men, 37 women) undergraduate students recruited from exercise classes. Results of these two studies suggest that the Physical Self-attribute Questionnaire is a viable tool to measure the underlying cognitive facets of subdomain-specific physical self-esteem.

A comparison of the impacts of continuous and interval cycle exercise on perceived exertion.

Ratings of perceived exertion (RPE) were developed to assess exertion during exercise testing. However, assessments of RPE prior to and after exercise have become common and potentially important in understanding exercise behaviour. The purpose of this project was to compare RPE taken before, during and after interval and continuous exercise sessions. Twenty-four participants (12 men, 12 women, body mass index = 24, VO2peak = 41 mL · kg · min(-1)) completed a maximal cycle ergometer test used to prescribe experimental trials: (1) moderate continuous (MC), (2) vigorous continuous (VC), (3) vigorous interval and (4) severe interval. All trials were 20 minutes in length and all intervals utilised 60-second segments and a 1:1 work-to-rest ratio. Predicted exertion was highest in the continuous vigorous trial (p < .05). Exertion increased from beginning to end in all trials (p < .05). Session RPE values were highest for the continuous vigorous trial (p < .05). Findings suggest that interval protocols produce perceptions of effort that are lower than VC exercise but similar to MC exercise. These results help describe the perceptions of effort associated with continuous and interval exercise and suggest that interval exercise can be performed with lower perceived work, which may encourage increased participation.

The Impact of Continuous and Interval Cycle Exercise on Affect and Enjoyment.

UNLABELLED: Rates of physical activity remain low despite public health efforts. One form of physical activity that provides significant physiological benefit but has not been evaluated in terms of affective and enjoyment responses is interval exercise. PURPOSE: The purpose of this study was to compare affect and enjoyment assessed before, during, and after interval and continuous exercise sessions. METHOD: Twenty-four participants (12 men, 12 women; body mass index = 24 ± 4, maximal oxygen consumption = 41 ± 5 mL/kg/min) completed a maximal cycle ergometer test used to prescribe experimental trials: (a) moderate continuous, (b) heavy continuous, (c) heavy interval, and (d) severe interval. All trials were 20 min in length, and all intervals utilized 60-s segments and a 1:1 work-to-rest ratio. RESULTS: Affective and enjoyment responses were significantly less positive for the heavy continuous trials in comparison with all other trials during exercise (p < .05; ES = .2-.8). Additionally, both severe and heavy interval exercise were more enjoyable than heavy continuous exercise (p > .05). CONCLUSION: Findings suggest that interval protocols produce affective and enjoyment responses that are equal to moderate continuous exercise and more positive than heavy continuous exercise. These results indicate that interval-based exercise may be a viable alternative to continuous exercise in the promotion of health and fitness.

Impact of high-intensity interval duration on perceived exertion.

PURPOSE: RPE is increasingly being considered as a viable tool beyond its original use for monitoring in-task exercise intensity. Research indicates that anticipated, in-task, and postexercise RPE values are often notably different from one another. An important new consideration is how perceptions are impacted by high-intensity interval training (HIT). This study aims to compare RPE responses before, during, and after continuous and HIT exercise trials. METHODS: Twenty (11 females and 9 males; mean ± SD age, 22 ± 4 yr) overweight (mean ± SD body mass index, 29 ± 3 kg·m(-2)) and unfit (mean ± SD V˙O2peak, 28 ± 5 mL·kg·min(-1)) participants completed a 20-min heavy continuous (HC) trial and three 24-min severe-intensity interval trials that utilized 1:1 work-to-recovery ratios: 30 s (Severe Interval-30), 60 s (Severe Interval-60), and 120 s (Severe Interval-120). Exertion was assessed using the Borg CR10 Scale. Data were analyzed using repeated-measures ANOVA and pairwise comparisons. RESULTS: Anticipated exertion was highest in the Severe Interval-120 trial (5.8 ± 2.0; P < 0.05) compared with other trials. Exertion increased from beginning to end in all trials (P < 0.05), with the greatest increases observed within the HC trial. Session RPE for the Severe Interval-120 trial (6.4 ± 2.3) was higher than those for all other trials (P < 0.05), and session RPE for the Severe Interval-30 trial (3.7 ± 1.8) was lower than that for the HC trial (4.9 ± 1.6; P < 0.05). CONCLUSIONS: These findings suggest that 30-s HIT protocols limit the perceptual drift that occurs during exercise, in comparison to HC exercise. Moreover, performing more intervals of shorter durations appears to produce lower postexercise RPE values than performing fewer intervals of longer duration and equal intensity. Because effort perception may influence behavior, these results could have implications for the prescription of interval training in overweight sedentary adults.

Differential impact of acute high-intensity exercise on circulating endothelial microparticles and insulin resistance between overweight/obese males and females.

BACKGROUND: An acute bout of exercise can improve endothelial function and insulin sensitivity when measured on the day following exercise. Our aim was to compare acute high-intensity continuous exercise (HICE) to high-intensity interval exercise (HIIE) on circulating endothelial microparticles (EMPs) and insulin sensitivity in overweight/obese men and women. METHODS: Inactive males (BMI = 30 ± 3, 25 ± 6 yr, n = 6) and females (BMI = 28 ± 2, 21 ± 3 yr, n = 7) participated in three experimental trials in a randomized counterbalanced crossover design: 1) No exercise control (Control); 2) HICE (20 min cycling @ just above ventilatory threshold); 3) HIIE (10 X 1-min @ ∼ 90% peak aerobic power). Exercise conditions were matched for external work and diet was controlled post-exercise. Fasting blood samples were obtained ∼ 18 hr after each condition. CD62E(+) and CD31(+)/CD42b- EMPs were assessed by flow cytometry and insulin resistance (IR) was estimated by homeostasis model assessment (HOMA-IR). RESULTS: There was a significant sex X exercise interaction for CD62E(+) EMPs, CD31(+)/CD42b- EMPs, and HOMA-IR (all P < 0.05). In males, both HICE and HIIE reduced EMPs compared to Control (P ≤ 0.05). In females, HICE increased CD62E(+) EMPs (P < 0.05 vs. Control) whereas CD31(+)/CD42b- EMPs were unaltered by either exercise type. There was a significant increase in HOMA-IR in males but a decrease in females following HIIE compared to Control (P<0.05). CONCLUSIONS: Overweight/obese males and females appear to respond differently to acute bouts of high-intensity exercise. A single session of HICE and HIIE reduced circulating EMPs measured on the morning following exercise in males but in females CD62E(+) EMPs were increased following HICE. Next day HOMA-IR paradoxically increased in males but was reduced in females following HIIE. Future research is needed to investigate mechanisms responsible for potential differential responses between males and females.

Sports game play: a comparison of moderate to vigorous physical activities in adolescents.

BACKGROUND: Research suggests participation in sports is an important contributor to overall adolescent physical activity (PA). Sports play has become increasingly important in physical education (PE) classes as a means for promoting healthful and enjoyable PA. Research is needed that investigates physiological and perceptual responses to sport play. METHODS: We studied 101 (55 males; 46 females, age 11-14) students who participated in flag football (FF), basketball (BB), and flag rugby (FR). Activity counts were collected using accelerometers. Perceived competence and enjoyment were measured using the intrinsic motivation inventory. RESULTS: Each sport activity produced acceptable levels of activity and positive perceptual responses, but differences among sports were noted. Accelerometry data indicated that FR and BB were more intense than FF (p < .001). Perceptual data indicated participation in FR elicited higher perceptions of competence and greater enjoyment when compared to FF and BB (p < .001). CONCLUSIONS: Participation in sport activity within middle school PE classes provides excellent opportunities for energy expenditure and positive perceptual responses. Most importantly, FR provides an activity stimulus that has potential benefits both physiologically and psychologically.

Comparisons of RPE before, during, and after self-regulated aerobic exercise.

UNLABELLED: Ratings of perceived exertion (RPE) were developed to provide a subjective estimation of exercise intensity during exercise but are also used to produce exercise intensities and to report the intensity of completed exercise sessions. PURPOSE: To determine the relationship between RPE assessed before, during, and after trials of RPE-based self-regulated aerobic exercise. METHODS: Twenty-six participants (10 males and 16 females) were tested for aerobic fitness. Participants completed three 30-min trials of treadmill exercise at a self-selected intensity corresponding to verbal prescriptions of light, moderate, and vigorous. Participants were instructed to adjust treadmill speed every 5 min to maintain the prescribed intensity. RPE using the OMNI picture system was taken immediately before, every 5 min during, immediately after, and 15 min after exercise. RESULTS: Treadmill speed increased during the moderate trial, and HR increased during all trials (P < 0.05). Predicted RPE and session RPE were higher than the average RPE for all sessions (P < 0.05) but not different than RPE values obtained at the end of the 30-min trials (P > 0.05). CONCLUSIONS: Findings suggest that predicted and session RPE are well matched to the exertion associated with the finishing minute of exercise sessions but are poorly matched to the majority of the exercise session. In-task RPE values tend to drift throughout exercise despite little or no change in treadmill speed and instructions to self-regulate exercise intensity. These findings indicate that RPE may be linked to exercise duration during self-regulated exercise. Additionally, session RPE ratings taken after exercise tend to reflect the close of exercise rather than the exertion associated with the exercise session as a whole.

Heart rate and metabolic responses to moderate-intensity aerobic exercise: a comparison of graded walking and ungraded jogging at a constant perceived exertion.

In this study, we assessed how ungraded jogging and graded walking at the same rating of perceived exertion (RPE) affect heart rate and oxygen consumption ([Vdot]O(2)). Twenty untrained participants completed a treadmill test to determine peak [Vdot]O(2) (mean = 40.3 +/- 6.3 ml . kg(-1) . min(-1)). Participants completed separate 30-min trials of moderate exercise (RPE of 13 on the Borg 6-20 scale) in random order on the treadmill: graded walking and ungraded jogging. Treadmill speed or grade was adjusted throughout the trial by the experimenter based on participant responses to maintain an RPE of 13. The jogging trial produced a significantly higher heart rate (161 +/- 18 vs. 142 +/- 24 beats . min(-1)) and [Vdot]O(2) (7.4 +/- 1.8 vs. 5.8 +/- 1.5 METs) (P < 0.01) than the walking trial. Treadmill grade decreased significantly during the walking trial (11.1 +/- 2.3% to 10.0 +/- 2.2%; P < 0.01), but treadmill speed did not change significantly during the jogging trial (5.2 +/- 1.0 miles . h(-1) to 5.0 +/- 0.9 miles . h(-1)) (P > 0.05), in an effort to maintain constant RPE. These findings provide evidence that similar perceptions of effort during graded walking and ungraded jogging do not produce similar cardiovascular and metabolic responses. The results indicate that, for a given prescribed perceived effort, jogging provides a greater stimulus for fitness benefits and caloric expenditure.