Self-selected Exercise Intensity Research Articles

The effects of affect-guided interval training on pleasure, enjoyment, and autonomy: A registered report

This registered report tested the effects of a novel exercise protocol, namely affect-guided interval training, on motivationally relevant variables of remembered pleasure, forecasted pleasure, enjoyment, and autonomy. Affect-guided interval training (AIT) consisted of 60-s intervals that alternated between the highest pleasant intensity and lowest pleasant intensity for 20 min; this was intended to minimize the potential displeasure of traditional high-intensity interval training. The novel protocol was compared to self-selected exercise intensity (30 min) and high-intensity interval training (60-s intervals for 20 min). All sessions were, on average, vigorous in intensity (80–89% peak heart rate). Data indicate that the AIT session was experienced as the most pleasant, had the most pleasant slope of affect, was remembered as the most pleasant, resulted in the most positive affective forecasts, and was the most enjoyable. Both the affect-guided interval session and self-selected exercise session resulted in greater autonomy than high-intensity interval training. Several evaluative and motivationally relevant variables, including (a) remembered pleasure, (b) enjoyment, and (c) forecasted pleasure were predicted by (a) experienced pleasure, the (b) pleasure experienced at the end of exercise, and (c) the slope of pleasure experienced throughout the exercise session. Overall, this study suggests that affect-guided interval training is a feasible and positive alternative that can be included as a viable option for exercise programming.

The Effect of Acute Exercise on State Anxiety: A Systematic Review.

Acute exercise has been shown to induce a small reduction in state anxiety, yet the most beneficial exercise stimulus is not clear. This review provides an update on the papers published since the last comprehensive review in 2015, with specific emphasis on whether study quality has improved. Randomised control trials, conducted in samples of healthy adults with non-clinical anxiety, were sourced from PubMed, PsycInfo, and Scopus. Study characteristics and study quality were assessed in nine studies comprising thirteen exercise conditions. Acute exercise significantly reduced anxiety in 53% (N = 7/13) of the exercise conditions. In comparison to a control condition, four showed exercising to be more effective, and one was as effective as the control. Two of the effective studies did not contain a control group. Six conditions were ineffective in reducing anxiety. There was no clear pattern of what combination of exercise mode, duration, and intensity was most effective, suggesting a variety may be effective in reducing anxiety. Methodological limitations still exist within the research, e.g., participant recruitment not considering baseline anxiety; variations in the control condition content. Future research should include participant samples exhibiting moderate-to-high levels of anxiety and examine self-selected exercise intensities.

A systematic narrative review of extrinsic strategies to improve affective responses to exercise.

Extrinsic strategies affect the exercise experience but fall outside the frequency, intensity, time, and type (i.e., dose-determining) principles. To our knowledge, no systematic review has focused on extrinsic strategies to influence the affective responses to exercise. The objective was to identify extrinsic strategies that seek to influence affective responses during exercise and other motivationally relevant variables including post-exercise momentary affective valence, remembered and forecasted pleasure, and enjoyment. For inclusion, eligible articles reported peer-reviewed original research, used acute bouts of exercise, and used a dimensional approach for measuring affective responses or measured enjoyment post-exercise. Web of Science, PubMed, and PsychINFO databases were last searched on 10th September 2021. Quality assessment was completed following the Effective Public Health Practice Project approach. Results were presented using a narrative synthesis. 125 studies were included with sample descriptions, study design (extrinsic strategies, mode, type, intensity, and duration), measurement details, and results summarised for each study. 71% of studies were categorised as Weak according to the quality assessment tool with sampling practices (self-referred participants) and poor reporting of participant withdrawals/drop-outs the predominant reasons for Weak ratings. A wide variety of extrinsic strategies were reported with music, music videos, immersive virtual reality, outdoor exercise, caffeine, high-to-low pattern of exercise intensity, self-selected exercise intensity, and manipulation of self-efficacy offering promise as suitable strategies to positively change how people feel during exercise. https://osf.io/jbh8v/.

Application of the Ratings of Perceived Exertion-Clamp Model to Examine the Effects of Joint Angle on the Time Course of Torque and Neuromuscular Responses During a Sustained, Isometric Forearm Flexion to Task Failure.

Abstract Smith, RW, Housh, TJ, Anders, JPV, Neltner, TJ, Arnett, JE, Schmidt, RJ, and Johnson, GO. Application of the ratings of perceived exertion-clamp model to examine the effects of joint angle on the time course of torque and neuromuscular responses during a sustained, isometric forearm flexion to task failure. J Strength Cond Res 37(5): 1023–1033, 2023—The present study used the ratings of perceived exertion (RPE)-clamp model during a sustained, isometric forearm flexion task to failure to determine the effects of joint angle on torque and neuromuscular responses. Twelve college-aged women performed two 3-second maximal voluntary isometric contractions at elbow joint angles (EJ) of 75°, 100°, and 125° before sustained, isometric, forearm flexions anchored to RPE = 7 to task failure (defined as RPE > 7, or the torque was reduced to zero) at EJ75, EJ100, and EJ125. The amplitude (AMP) and frequency (MPF) of the electromyographic (EMG) and mechanomyographic (MMG) signals from the biceps brachii were recorded. Repeated-measures ANOVAs and post hoc comparisons were used to examine differences across time and between joint angles for torque and neuromuscular parameters. A p-value ≤0.05 was considered significant. For each joint angle, there was a decrease (p < 0.05) in torque across the sustained, isometric task. Collapsed across joint angle, there were decreases (p < 0.001, = 0.378) in EMG AMP from 30 to 100% time to task failure. No changes were observed, however, for the other neuromuscular responses. The subjects voluntarily reduced torque to maintain RPE = 7 for each joint angle, and we hypothesize that RPE was maintained by afferent feedback from group III/IV motor neurons and corollary discharge (efferent copy of an internal signal that develops from central motor commands). The RPE-Clamp Model may be extended to athletes recovering from injury because a self-selected exercise intensity may be perceived as more enjoyable and promote adherence.

Caffeine increases exercise intensity and energy expenditure but does not modify substrate oxidation during 1h of self-paced cycling.

Oral caffeine intake has been deemed as an effective supplementation strategy to enhance fat oxidation during aerobic exercise with a steady-state intensity. However, in real exercise scenarios, individuals habitually train with autoregulation of exercise intensity. This study aimed to analyze the effect of oral caffeine intake during self-paced cycling on autoregulated exercise intensity and substrate oxidation. Fifteen young and healthy participants (11 men and 4 women) participated in a double-blind, randomized, cross-over investigation. Each participant took part in 2 experimental days consisting of pedaling for 1h with a self-selected wattage. Participants were told that they had to exercise at a moderate intensity to maximize fat oxidation. On one occasion participants ingested 3mg/kg of caffeine and on the other occasion ingested a placebo. Energy expenditure, fat oxidation rate, and carbohydrate oxidation rate were continuously measured during exercise by indirect calorimetry. In comparison to the placebo, caffeine intake increased the self-selected wattage (on average, 105 ± 44 vs 117 ± 45W, respectively, P < 0.001) which represented a higher total work during the cycling session (377 ± 157 vs 422 ± 160kJ, P < 0.001). Caffeine increased total energy expenditure (543 ± 161 vs 587 ± 155kcal, P = 0.042) but it did not affect total fat oxidation (24.7 ± 12.2 vs 22.9 ± 11.5g, P = 0.509) or total carbohydrate oxidation (87.4 ± 22.4 vs 97.8 ± 32.3g, P = 0.101). Acute caffeine ingestion before an exercise session with an individual's freedom to regulate intensity induces a higher self-selected exercise intensity and total work. The selection of a higher exercise intensity augments total energy expenditure but eliminates the effect of caffeine on substrate oxidation during exercise.

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

ABSTRACT 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.

Validation and Usability Evaluation of Mobile Application to Monitor Real-Time Exercise Heart Rate Zone

A mobile application to monitor heart rate (HR) during an exercise called Chromozone was developed to enable a user to regulate exercise intensity using a color-coded system rather than numerical display in the most conventional device. In this study, the agreement of HR from Chromozone was compared against the HR dataset from a clinically accepted electrocardiogram (ECG) on different exercise intensity and to assess its reliability by intra-day repeated assessments. Additionally, the usability aspect of the Chromozone smartphone application was also assessed. Forty-two participants underwent self-selected exercise intensities (based on individual HR reserve) included for 5-min followed by a cool-down period (3-min). A 20-min rest period was given to the participant before repeating the same exercise protocol two more times. Chromozone was found to generate excellent criterion-concurrent validity (r = 0.998, p &lt; 0.001) and acceptable bias of 1.96 bpm (Limits of Agreement; LoA: 3.07 to -3.51) for relative and absolute agreement, respectively. Similarly, relative (intraclass correlation coefficient test: 0.998, p &lt; 0.001) and absolute (within-subject coefficient of variation: 1.95 ± 1.4%) reliability using Chromozone application shows an excellent consistency. Additionally, this study also showed that the usability level of the Chromozone application is beyond the satisfactory level. The outcome of this work provides strong support for Chromozone application as a valid and reliable exercise HR monitoring tool that could potentially help athletes, active individuals as well as the clinical population to monitor and regulate their exercise training regime more effectively.

Can the add-on placebo effect augment the physical and mental health outcomes of exercise? A meta-analysis.

This study aimed to clarify whether the add-on placebo effect can augment the psychological and physiological benefits of exercise. The inclusion criteria were met by 18 studies with 1,221 participants. The add-on placebo effects promoted a more positive affect (g = 0.430), greater self-esteem (g = 0.454), improved cardiorespiratory fitness (g = 0.273), and decreased perceived exertion (g = 0.476) and blood pressure (g = 0.268). Improved affect benefits were moderated by placebo type (elaboration > external medium), self-selected exercise intensity (no > yes), and exercise type (running > nonspecific). The results support the proposal that the add-on placebo effect can provide significant positive benefits for exercisers, particularly in terms of psychological responses.

Cardiovascular Effects of Aerobic Exercise With Self-Selected or Predetermined Intensity in Adolescents With Obesity.

This study compared the effects of self-selected exercise intensity (SEI) versus predetermined exercise intensity (PEI) on blood pressure (BP) and arterial stiffness in adolescents with obesity. A total of 37 adolescents, 14.7 (1.6)years old, body mass index ≥95th percentile were randomly allocated into SEI (n = 18; 12 boys) or PEI (n = 19; 13 boys). Both groups exercised for 35minutes on a treadmill, 3 times per week, for 12weeks. The SEI could set the speed at the beginning of the sessions and make changes every 5minutes. The PEI adolescents were trained at an intensity set at 60% to 70% of heart rate reserve. Brachial and central BP, pulse pressure, augmentation index, and carotid-femoral pulse wave were determined at baseline and after 12weeks. Both groups reduced brachial systolic BP (SEI, Δ = -9mm Hg; PEI, Δ = -4mm Hg; P < .01), central systolic BP (SEI, Δ = -4mm Hg; PEI, Δ = -4mm Hg; P = .01), and central pulse pressure (SEI, Δ = -4mm Hg; PEI, Δ = -3mm Hg; P = .02) without differences between groups. No changes in the augmentation index and carotid-femoral pulse wave were observed in either group. The SEI induced similar changes in various cardiovascular outcomes compared with PEI in adolescents with obesity.

The Effect of Metformin on Self-Selected Exercise Intensity in Healthy, Lean Males: A Randomized, Crossover, Counterbalanced Trial.

IntroductionIn general, patients with type 2 diabetes have lower cardiorespiratory fitness levels and perform exercise at lower intensities compared to healthy controls. Since metformin (MET) has been shown to increase the rate of perceived exertion (RPE) during exercise with a fixed intensity, MET per se may reduce self-selected exercise intensity. The aim of this study was to assess the effect of MET on self-selected exercise intensity.MethodsHealthy males were eligible for this crossover, counterbalanced study with two treatment periods: MET and placebo (PLA), each lasting 17 days. Treatment dose was gradually increased and reached 2 g/day on treatment day 9, and continued at that level for the rest of the treatment period. The two periods were performed in randomized order. Two experimental days (A+B) were conducted on Day 15 (A) and Day 17 (B) of each period, respectively. Day A consisted of an exercise bout with self-selected exercise intensity (equal to RPE = 14–15 on the Borg Scale). Day B consisted of an exercise bout with fixed intensity (70% of VO2peak). Oxygen consumption rate was assessed continuously during both exercise bouts.ResultsFifteen males (age 23.7 ± 0.6 years, BMI 22.3 ± 2.0, VO2peak 3.5 ± 0.6 L/min) were included in the study. On Day B, RPE was higher in MET compared to PLA (14.8 ± 0.4 vs. 14.0 ± 0.3, P = 0.045). On Day A, no difference in self-selected exercise intensity measured by oxygen consumption rate (PLA 2.33 ± 0.09 L O2/min, MET 2.42 ± 0.10 L O2/min, P = 0.09) was seen between treatment periods.ConclusionsSelf-selected exercise intensity was not reduced by MET in healthy males, despite the fact that MET increased RPE during an exercise bout with fixed intensity.

Changes in Strength, Mobility, and Body Composition Following Self-Selected Exercise in Older Adults.

The purpose of this trial was to examine the effects of self-selected exercise intensities plus either whey protein or placebo supplementation on vital signs, body composition, bone mineral density, muscle strength, and mobility in older adults. A total of 101 participants aged 55 years and older (males [n = 34] and females [n = 67]) were evaluated before and after 12 weeks of self-selected, free-weight resistance exercise plus 30 min of self-paced walking three times per week. The participants were randomized into two groups: whey protein (n = 46) or placebo (n = 55). Three-way mixed factorial analyses of variance were used to test for mean differences for each variable. The 12 weeks of self-selected, self-paced exercise intensities improved resting heart rate, fat-free mass, percent body fat, handgrip strength, bench press strength, leg press strength, and all mobility measurements (p < .05) in males and females despite supplementation status. This suggests that additional protein in well-fed healthy older adults does not enhance the benefit of exercise.

Self-selected exercise intensity for inactive hypertensive older women: a pilot study

Self-selected exercise intensity (SSE) is a simple approach to encourage an active lifestyle. This study aimed to investigate whether a SSE intensity session meet the recommended intensity for hypertension management (i.e. moderate-vigorous), and whether heart rate (HR), rating of perceived exertion (RPE) and affective responses are reproducible. Thirteen inactive hypertensive older women (age: 64.54 ± 4.16 years; blood pressure: 122.51/62.15 mmHg) performed two 30-minute SSE intensity sessions outdoors. HR reserve (HRR), RPE and affective responses were assessed. Paired t-test, intraclass correlation coefficient (ICC) and typical error (TE) were used for the analyzes. Participants exercised at moderate-vigorous intensity (≥ 40% of HRR). No differences were found for HRR (56.46 ± 8.01% vs. 59.08 ± 10.57%), RPE (11.26 ± 1.14 vs. 10.98 ± 1.52) and affective response (3.47 ± 1.13 vs. 3.38 ± 1.23) (p &gt; 0.05). RPE showed excellent reliability (ICC = 0.82; 95%CI: 0.42; 0.94; p = 0.003). There was a poor reliability for HRR (ICC = 0.40; 95%CI: -0.97; 0.82; p = 0.193) and affective responses (ICC = 0.19; 95%CI: -2.10; 0.76; p = 0.369). TE between sessions for HRR, RPE, and affective response were 8.11 bpm, 0.75 and 1.11, respectively. In conclusion, inactive hypertensive older women seem to meet the recommended intensity for hypertension management when they exercise at a self-selected pace and report it as light-moderate and pleasant. Despite only RPE, but not HR and affective response, has shown good reproducibility, the results seem to support the use of SSE intensity as a simple approach to encourage an active lifestyle in this population.

Acute antihypertensive effect of self-selected exercise intensity in older women with hypertension: a crossover trial.

PurposeAcute reduction in blood pressure (BP) following an exercise session is evidenced in controlled settings with formal supervision in hypertensive older populations. This study investigated the effect of a self-selected exercise (SSE)-intensity session on ambulatory BP in hypertensive older women in a “real-world” setting.MethodsTwenty inactive older women with hypertension (64.9±4.5 years) were included in this randomized, controlled, crossover trial. After baseline assessments, participants performed 30 minutes of an SSE-intensity session on an outdoor track and a control session, separated by 7-10 days. Heart rate (HR), rating of perceived exertion (RPE), and affective response were assessed. Ambulatory BP was monitored for 20 hours following both sessions. Paired t-tests and generalized estimation were used for data analysis.ResultsParticipants exercised at 5.1±1.1 km/h, spent ~90% of the exercise time at moderate–vigorous intensity (≥40% of heart rate reserve). SSE-intensity session was reported as light (RPE 11.0±1.5) and pleasant (affect 3.4±1.2). SSE-intensity session elicited reductions in systolic BP in the first 6 hours postexercise (6.0 mmHg, CI 2.7–9.3 mmHg; P<0.001). Average systolic BP in the 20-hour (−3.4 mmHg, CI −5.9 to −0.9 mmHg; P=0.010) and awake (−4.0 mmHg, CI −6.4 to −1.6 mmHg; P=0.003) periods were lower following SSE-intensity session compared to control session. No differences were observed in average systolic BP during asleep period and diastolic BP during the 20-hour awake and asleep periods between the SSE-intensity session and control session (P>0.05).ConclusionAn SSE-intensity session elicited a reduction in ambulatory systolic BP in inactive older women with hypertension during awake and 20-hour periods. Also, the SSE-intensity session was reported as light and pleasant.

Blood cardiac biomarkers responses are associated with 24 h ultramarathon performance

PurposeClinical significance of cardiac biomarkers response in ultra-endurance runners are not completely elucidated because events vary in distance/duration and competitors modulate running intensity according to individual running capacity. The aim of this study was to examine the relationship between self-selected exercise intensity with cardiac biomarkers comparing experienced (EXP, N = 11) and novice (NOV, N = 14) runners able to finish a 24h ultramarathon (24UM) with significant differences in performance. MethodsCardiac biomarkers (i.e. CKMB/totalCK, cTnT and NT-proBNP), inflammatory markers (i.e. leukocytes and CRP) and cortisol were analyzed before and after a 24UM. ResultsEXP finished the race with significant (p < 0.05) longer distance than NOV (158.8 ± 15.8 vs 116.8 ± 10.3 Km). Two-way mixed ANOVA showed significant time × performance level interaction with greater increase of cTnT (F(1,23) = 6.18, p = 0.021), NT-proBNP (F(1,23) = 9.27, p = 0.006) and cortisol (F(1, 23) = 5.13, p = 0.03) in the EXP group. CKMB/totalCK (F(1, 23) = 71.90, p < 0.0001) decreased while leukocytes (F(1, 23) = 100.06, p < 0.0001) and CRP (F(1, 23) = 93.37, p < 0.0001) increased in both groups (main effect of time). Correlations were found between 24UM distance and cortisol (r = 0.58; p = 0.002), CKMB (r = 0.47; p = 0.017), cTnT (r = 0.44; p = 0.027) or NT-proBNP (r = 0.56; p = 0.003). Cortisol and NT-proBNP were also significantly correlated (r = 0.51; p = 0.01). ConclusionsAlthough there is no clear evidence of cardiac risk when comparing cardiac biomarkers levels with clinical cut-off values, cardiac biomarkers are associated with running performance and pituitary-adrenocortical system response. In EXP runners, higher levels of cardiac biomarkers and cortisol suggest a more hemodynamically challenged heart during prolonged endurance exercise.

The Absolute and Relative Reliability of Psychophysiological Responses to Self-Selected Exercise Intensity in Elderly Women

ABSTRACTBackground: Self-selected exercise intensity (SSEI) promotes higher affect (pleasure) during exercise, but its reliability is still unclear. Purpose: to evaluate the test-retest reliability and the minimum detectable change of the perceptive and physiological responses in two sessions of SSEI on treadmill in elderly women. Method: Twenty elderly women (ages 65.3 ± 4.2 years) performed two 20-min laboratory-based treadmill aerobic exercise sessions with self-selected intensity. During the sessions, %VO2max, %HRreserve, affect, and rating of perceived exertion (RPE) were recorded. Reliability was calculated using the intraclass correction coefficient (ICC) and Bland–Altman plots. The minimum detectable change (MDC) was also calculated. Results: ICC values were 0.98 for % VO2max, 0.83 for % HRreserve, 0.85 for affect, and 0.80 for RPE. No differences were observed in mean values between sessions for all the variables. MDCs were lower than 0.7% for VO2max, 11.7% for HRreserve, 0.7 for affect, and 0.8 for RPE. Bland–Altman plots showed a bias of 0.50% for HRreserve, 3.2% for VO2max, 0.05 for affect, and −0.35 for RPE. Conclusion: Self-selected intensity during aerobic exercise performed on treadmill is reliable, which promotes adequate and lower MDC values on physiological and perceptual responses in elderly women.

Exposure to high solar radiation reduces self-regulated exercise intensity in the heat outdoors

High radiant heat load reduces endurance exercise performance in the heat indoors, but this remains unconfirmed in outdoor exercise. The current study investigated the effects of variations in solar radiation on self-regulated exercise intensity and thermoregulatory responses in the heat outdoors at a fixed rating of perceived exertion (RPE). Ten male participants completed 45-min cycling exercise in hot outdoor environments (about 31°C) at a freely chosen resistance and cadence at an RPE of 13 (somewhat hard). Participants were blinded to resistance, pedal cadence, distance and elapsed time and exercised at three sunlight exposure conditions: clear sky (mean ± SD: 1072 ± 91 W·m−2; HIGH); thin cloud (592 ± 32 W·m−2; MID); and thick cloud (306 ± 52 W·m−2; LOW). Power output (HIGH 96 ± 22 W; MID 103 ± 20 W; LOW 108 ± 20 W) and resistance were lower in HIGH than MID and LOW (P < .001). Pedal cadence was lower, the core-to-skin temperature gradient was narrower, body heat gain from the sun (SHG) was greater and thermal sensation was higher with increasing solar radiation and all variables were different between trials (P < .01). Mean skin temperature was higher in HIGH than MID and LOW (P < .01), but core temperature was similar between trials (P = .485). We conclude that self-regulated exercise intensity in the heat outdoors at a fixed RPE of somewhat hard is reduced with increasing solar radiation because of greater thermoregulatory strain, perceived thermal stress and SHG. This suggests that reduced self-selected exercise intensity during high solar radiation exposure in the heat may prevent excessive core temperature rise.

Exergaming: Feels good despite working harder.

Strategies to encourage exercise have led to research on cycle ergometer ‘exergaming’, as a means of enhancing exercise enjoyment. This research has typically prescribed the exercise intensity and used one exercise mode. The aim of this study was to compare self-selected exercise intensity on a cycle ergometer with and without exergaming modes activated. A total of 20 participants aged between 18–40 years (M = 24.2 ± 5.9) completed a sub-maximal exercise test. Participants returned two days later to complete one 45 minute session of self-selected exercise with 15 minutes in each of ‘control’ (standard ergometer), ‘track’, and ‘game’ modes, with order randomized. Heart rate, work rate, perceived exertion, and affective valence were recorded during exercise. Dissociation and enjoyment were recorded in the rest interval between each mode. Participants exercised above ventilatory threshold (VT) in all three modes (track, M = 9.5 ± 12%; game, M = 6.2 ± 12%; and control, M = 4.4 ± 14% above VT) and at higher work rates (P < 0.05) exergaming (track, M = 94.5 ± 27.9; game, M = 96.2 ± 32.8 watts) than control (M = 86.6 ± 26.5 watts). Despite exercising at a higher intensity, participants perceived exercise during the exergaming modes to be most pleasant (P < 0.01), with greater enjoyment (P < 0.01) and dissociation (P < 0.01) in the game than track mode, and both modes higher on these variables than the control mode. Findings support the use of exergaming as a strategy to encourage individuals to exercise, with participants choosing to work harder physiologically, but reporting more positive psychological responses during and following the exercise.

The reliability and minimal detectable change of the cardiovascular response and self-selected exercise intensity during forward and backward treadmill exercise in individuals with Parkinson disease.

Objective:This study examined test–retest relative (intraclass correlation coefficient) and absolute (minimum detectable change) reliabilities for heart rate, blood pressure, rate of perceived exertion, and the cerebral oxygen response during both forward and backward treadmill walking in clients with Parkinson disease. In addition, the intensity of exercise based on the individual’s heart rate response during forward and backward walking treadmill work was assessed.Design:Test–retest reliability study.Subjects:A total of 22 clients with Parkinson disease (Hoehn and Yahr stages 1–3).Main measures:Outcome measures of heart rate, blood pressure, and cerebral oxygen response were assessed during forward and backward walking on a treadmill for a total of 20 minutes up to an intensity based on the clients’ prior treadmill work and their rate of perceived exertion.Results:Good to excellent 6–8 day test–retest findings for both forward (intraclass correlation coefficient(2,1), 0.89–0.99) and backward (intraclass correlation coefficient(2,1), 0.82–0.99) treadmill walking were found for heart rate, blood pressure, cerebral oxygen response, and the participants’ rate of perceived exertion. Low minimum detectable change (MDC)95 values were found for heart rate (4.9 and 4.8), rate of perceived exertion (1.0 and 1.6), and cerebral oxygen response (1.2 and 0.92), during forward and backward walking, respectively. All treadmill exercise heart rates attained by participants were within an intensity of 54%–87% of the client’s predicted maximal heart rate.Conclusion:Treadmill exercise training can be included in Parkinson disease exercise programs with relative confidence in test–retest reliability of cardiovascular response. It was also demonstrated that individuals with Parkinson disease previously involved with exercise consistently self-select walking speeds which induce heart rates within recommended guidelines for positive cardiovascular adaptation.

Rate dependent influence of arterial desaturation on self-selected exercise intensity during cycling.

The purpose of this study was to clarify if Ratings of Perceived Exertion (RPE) and self-selected exercise intensity are sensitive not only to alterations in the absolute level of arterial saturation (SPO2) but also the rate of change in SPO2. Twelve healthy participants (31.6 ± 3.9 y, 175.5 ± 7.7 cm, 73.3 ± 10.3 kg, 51 ± 7 mL·kg-1·min-1 ) exercised four times on a cycle ergometer, freely adjusting power output (PO) to maintain RPE at 5 on Borg’s 10-point scale with no external feedback to indicate their exercise intensity. The fraction of inspired oxygen (FIO2) was reduced during three of those trials such that SPO2 decreased during exercise from starting values (>98%) to 70%. These trials were differentiated by the time over which the desaturation occurred: 3.9 ± 1.4 min, -8.7 ± 4.2%•min-1 (FAST), 11.0 ± 3.7 min, -2.8 ± 1.3%•min-1 (MED), and 19.5 ± 5.8 min, -1.5 ± 0.8%•min-1 (SLOW) (P < 0.001). Compared to stable PO throughout the control condition (no SPO2 manipulation), PO significantly decreased across the experimental conditions (FAST = 2.8 ± 2.1 W•% SPO2-1; MED = 2.5 ± 1.8 W•% SPO2-1; SLOW = 1.8 ± 1.6 W•% SPO2-1; P < 0.001). The rates of decline in PO during FAST and MED were similar, with both greater than SLOW. Our results confirm that decreases in absolute SPO2 impair exercise performance and that a faster rate of oxygen desaturation magnifies that impairment.

Feed-forward regulation of self-selected exercise intensity in response to different rates of arterial deoxygenation.

Arterial desaturation impairs exercise performance in a dose-dependent manner. However, new theories of exercise-induced fatigue suggest that increasing rates of arterial deoxygenation augment the fatigue response during exercise. The purpose of this dissertation is to clarify if self-selected exercise intensity, while exercising at a constant rate of perceived exertion (RPE), is sensitive to alterations in the absolute arterial saturation (SPO2) and/or the rate of change in SPO2. Subjects performed constant RPE exercise for 30 min. They were instructed to adjust their exercise intensity during the trial to maintain their RPE at 5 on Borg's 10-point scale. Subjects engaged in continuous bilateral, isokinetic cycling and intermittent, unilateral, isometric knee-extension. The fraction of inspired oxygen was reduced to desaturate arterial blood from starting values (>98%) to 70%. This desaturation occurred linearly over 3 target time periods (FAST, 5 min; MED, 15 min; SLOW, 25 min). The rate of arterial desaturation was significantly different between each of the 3 conditions. During cycling exercise, PO (FAST = 2.8 ± 2.1 W·% SPO2-1; MED = 2.5 ± 1.8 W·% SPO2-1; SLOW = 1.8 ± 1.6 W·% SPO2-1; P < 0.001) and surface electromyography (sEMG) of the vastus medialis (FAST = 1.3 ± 0.6%·% SPO2-1; MED = 1.1 ± 0.5%·% SPO2-1; SLOW = 0.7 ± 0.7%·% SPO2-1; P < 0.001) decreased at significantly different rates. Post hoc comparisons revealed that the rates of decline in PO and sEMG during FAST and MED were similar, and both were greater than SLOW. However, during isometric knee extension exercise, the level of force production and sEMG remained similar across saturation levels. These results confirm that decreases in absolute SPO2 impair self-selected exercise intensity and that faster desaturation rates magnify that impairment, but only when a large muscle mass is engaged. These findings suggest that the rate of arterial deoxygenation independently influences exercise performance and that the central depressant effect may be a function of the metabolic strain associated with hypoxia, rather than the hypoxia per se.