Predictors of change in affect in response to high intensity interval exercise (HIIE) and sprint interval exercise (SIE)

No Sex Differences in Perceptual Responses to High-Intensity Interval Training or Sprint Interval Training

ABSTRACT

Coe, LN and Astorino, TA. No sex differences in perceptual responses to high-intensity interval training or sprint interval training. J Strength Cond Res 36(6): 1025-1032, 2024-High-intensity interval training (HIIT) elicits similar and, in some cases, superior benefits vs. moderate-intensity continuous training (MICT). However, HIIT is typically more aversive than MICT because of the higher intensity and in turn, greater blood lactate accumulation (BLa). This study explored potential sex differences in perceptual responses to acute HIIT and sprint interval training. Fifteen men (age and V̇O2max = 29 ± 8 years and 39 ± 3 ml·kg-1·min-1) and 13 women (age and V̇O2max = 22 ± 2 years and 38 ± 5 ml·kg-1·min-1) who are healthy and recreationally active initially underwent testing of maximal oxygen uptake (V̇O2max) on a cycle ergometer. In randomized order on 3 separate occasions, they performed the 10 × 1-minute protocol at 85% of peak power output, 4 × 4-minute protocol at 85-95% maximal heart rate (%HRmax), or reduced exertion high intensity interval training consisting of 2 "all-out" 20-second sprints at a load equal to 5% body mass. Before and throughout each protocol, rating of perceived exertion (rating of perceived exertion [RPE] 6-20 scale), affective valence (+5 to -5 of the Feeling Scale), and BLa were assessed. Five minutes postexercise, enjoyment was measured using the Physical Activity Enjoyment scale survey. Results showed no difference in RPE (p = 0.17), affective valence (0.27), or enjoyment (p = 0.52) between men and women. Blood lactate accumulation increased in response to all protocols (p < 0.001), and men showed higher BLa than women (p = 0.03). Previous research suggests that interval exercise protocols are not interchangeable between men and women, yet our data reveal that men and women having similar V̇O2max exhibit no differences in perceptual responses to interval exercise.

Shorter Versus Longer Durations of Rowing-Based Interval Exercise Attenuate the Physiological and Perceptual Response

Purpose: This study compared physiological and perceptual variables between short and long durations of rowing-based high intensity interval exercise (HIIE). Methods: Fourteen active adults (age = 26.4 ± 7.2 yr) performed incremental rowing exercise to fatigue to measure maximal oxygen uptake (VO2max) and peak power output (PPO). The subsequent 20 min sessions required HIIE (eight 60 s efforts at 85%PPO with 90 s of active recovery at 20%PPO or 24 20 s efforts at 85%PPO with 30 s of active recovery at 20%PPO) or moderate intensity continuous exercise (MICE) at 40%PPO. During exercise, VO2, heart rate (HR), blood lactate concentration (BLa), rating of perceived exertion (RPE), and affective valence were measured. Results: Data show significantly (p < 0.001) higher peak VO2 (84 ± 7 vs. 76 ± 5%VO2peak, d = 0.99), peak HR (94 ± 4%HRpeak vs. 90 ± 4%HRpeak, d = 1.12), BLa (7.0 ± 2.5 mM vs. 4.1 ± 1.0 mM, d = 1.22), end-exercise RPE (12.8 ± 2.0 vs. 11.0 ± 1.7, d = 1.29), and lower affective valence (2.1 ± 1.6 vs. 2.9 ± 1.2, d = 0.61) with long versus short HIIE. Time spent above 85%HRpeak was significantly higher (p < 0.001) in short versus long HIIE (606 ± 259 vs. 448 ± 26 s, d = 0.91). Conclusion: Longer rowing-based intervals elicit greater cardiometabolic and perceptual strain versus shorter efforts, making the latter preferable to optimize perceptual responses to HIIE.

Acute Physiological Responses to Moderate-Intensity Continuous, High-Intensity Interval, and Variable-Intensity Intermittent Exercise

Purpose: This study examined acute physiological responses to moderate-intensity continuous exercise (MICE), variable-intensity intermittent exercise (VIIE), and high-intensity interval exercise (HIIE) protocol, matched for total work output in healthy adults (n = 8, age = 25.1 ± 6.0 yrs). Methods: Three experimental trials were completed in a random order. MICE was continuous exercise at 40% of peak work rate (WR_peak). VIIE consisted of sixteen 10-sec bursts at 120% WRpeak, sixteen 20-sec bursts at 60% WR_peak and recovery at 20% WR_peak interspersed throughout the protocol. HIIE consisted of eight intervals of 2 minutes at 70% WR_peak and 1 minute at 20% WR_peak. Oxygen consumption during work-intervals and time within moderate and vigorous-intensity zones determined the magnitude and duration of physiological stresses. Perceptual responses were measured by affective response and post-exercise enjoyment (PACES). Repeated-measure ANOVAs analyzed differences between trials. Statistical significance was established if p ≤ 0.05. Results: Oxygen consumption during work-intervals in VIIE was greater than MICE, but less than HIIE. VIIE and HIIE had similar duration within vigorous-intensity zone (11.1 ± 3.5 min vs. 13.5 ± 1.3 min); both were greater than MICE (4.9 ± 1.1 min). The time spent in the moderate-intensity zone was different between all trials (VIIE = 11.1 ± 2.0 min; MICE = 17.4 ± 5.2 min; HIIE = 4.9 ± 0.4 min). Affective responses were similar among all trials. Post-exercise enjoyment was greater in VIIE than HIIE; both were not different from MICE. Conclusion: These results suggests the VIIE paradigm could be a viable alternative to HIIE and MICE protocols.

Investigating Affective Responses to Remotely Delivered "At Home" Low Volume High Intensity Interval Exercise: A Non-Randomized Parallel Group Feasibility Study

Background

Low volume-high intensity interval exercise (LV-HIIE) has gained interest, due to its efficiency in invoking health and fitness benefits. However, little research has studied "at home" feasibility or effects of LV-HIIE. This study aimed to demonstrate that remote "at-home" LV-HIIE research is possible and to investigate if affective responses to the LV-HIIE protocol, subsequent intentions, and self-efficacy to repeat were related to self-reported tolerance of the intensity of exercise.

Methods

Using self-reported tolerance of the intensity of exercise, 41 healthy, physically active participants (25 female and 16 male; age 21.3 ± 1.0 years, body mass index 23.0 ± 2.9 kg.m2) were divided into low tolerance (LT, n = 14), middle tolerance (MT, n = 15), and high tolerance (HT, n = 12) groups. Participants completed a 20-min LV-HIIE circuit training video [2 × (10 ×30 s work, 15 s rest)] at home. Participants reported ratings of perceived exertion, affective valence, and perceived activation at baseline, during the protocol, immediately post-protocol, and during the cool down. 20-min after completion, respondents answered questions on exercise task self-efficacy and intentions to repeat LV-HIIE.

Results

The study recruited n = 65 individuals, of whom n = 50 passed screening. Ultimately n = 41 (82%) completed the exercise protocol and data collection. Ratings of perceived exertion were not significantly different between groups (p = 0.56), indicating similar perceptions of task difficulty. There was no significant effect of tolerance on affective valence (p = 0.36) or felt arousal (p = 0.06). There was evidence of high individual variability in affective responses within and between participants. Subsequent intentions and self-efficacy to repeat the exercise protocol did not seem to be related to affective valence during or after the protocol.

Discussion

Recruitment and data collection indicated that research into "at home" LV-HIIE is possible. High individual differences in affective responses suggest that LV-HEII may be appropriate for some but not all as an exercise option. Assessing self-reported tolerance of intensity of exercise may not appropriately identify whether or not LV-HIIE will be suitable for an individual.

Physiological, perceptual and affective responses to high-intensity interval training using two work-matched programs with different bout duration in obese males

Objectives

This study compared physiological, perceptual, and affective responses to high-intensity interval training (HIIT) between two work-matched programs with different bout durations in obese males.

Methods

Sixteen low-to-moderately active obese men completed an eight-week cycling program of supervised HIIT (3 days/week) using either short bouts [48 × 10 s at 100% of peak power output (PPO) with 15 s of recovery (HIIT10)] or long bouts [8 × 60 s at 100% PPO with 90 s of recovery (HIIT60)]. Workload was progressively adjusted, to maintain high intensity (100% PPO), throughout training. Blood lactate (BLa), heart rate (HR), ratings of perceived exertion (RPE), and feeling scale ratings (pleasure/displeasure) were measured in each HIIT session.

Results

Average HR decreased in the last 2 weeks of training in both groups by 2.2 ± 1.8% of peak HR (p < 0.001). Training resulted in a reduction in BLa during exercise by 28 ± 19% (p < 0.001) from the 10th min onward only in HIIT10. Similarly, during the last weeks of training, RPE decreased (by 1.0 ± 1.1 units, p < 0.05) and feeling scale ratings were improved only in HIIT10, while RPE remained unchanged and feeling scale ratings deteriorated in HIIT60 (from 3.0 ± 1.1 to 2.1 ± 0.9 units, p < 0.001). No differences in post-exercise enjoyment were found.

Conclusion

Both HIIT formats induced similar HR adaptations, but improvement of BLa, perceptual and affective responses occurred only when bout duration was shorter. Our findings suggest that, in low-to-moderately active obese men, HIIT may be more effective in improving metabolic, perceptual, and affective responses when shorter, rather than longer, bouts of exercise are used.

Bout duration in high-intensity interval exercise modifies hematologic, metabolic and antioxidant responses

Objective

This study compared hematologic, metabolic and antioxidant responses between three high-intensity interval exercise (HIIE) trials of different bout duration and a continuous exercise trial (CON), all with equal average intensity, total work, and duration.

Methods

Eleven healthy young males performed four trials involving 20 min of cycling, either continuously (49% of power at VO₂max, PPO), or intermittently with 48 10-s bouts (HIIE10), 16 30-s bouts (HIIE30) or 8 60-s bouts (HIIE60) at 100% PPO, with a 1:1.5 work-to-recovery ratio at 15% PPO. Venous blood was obtained before, immediately after, and 1 h post-exercise to evaluate hematologic, metabolic and antioxidant responses. Blood lactate concentration was measured in capillary blood during exercise, while urine lactate was measured before and 1 h post-exercise.

Results

Post-exercise leukocyte count (mean ± SD; 9.7 ± 2.8 k μL^-1), uric acid concentration (0.35 ± 0.10 mmol L^-1), glucose concentration (6.56 ± 1.44 mmol L^-1), and plasma volume change (-13.5 ± 4.4%) were greater in HIIE60 compared to all other trials (p < 0.05). One-hour post-exercise, lymphocytes decreased below pre-exercise values in all HIIE trials, and uric acid increased in the HIIE60 trial (p < 0.05). Urine lactate concentration 1 h post-exercise increased compared to pre-exercise only in HIIE60 (19-fold, p < 0.001), and this was related with the higher blood lactate concentration during exercise in that trial.

Conclusions

These findings highlight the importance of bout duration, given that shorter bouts of HIIE (30 s or 10 s) induce lower blood cell perturbations, metabolic stress, and antioxidant responses compared to the commonly used 1-min bouts, despite equal total work, duration, and work-to-recovery ratio.

A Pilot Study on In-Task Affect Predicting Free-Living Adherence to HIIT and MICT

Purpose: To report pilot test findings on whether in-task affect during a supervised exercise program, where participants were randomized to either moderate-intensity continuous training (MICT) or high-intensity interval training (HIIT), predicts changes in moderate-to-vigorous physical activity (MVPA-Total and MVPA10+ in bouts of ≥ 10 min) at 1- and 6-month post-intervention. Method: This experimental study design randomized 32 inactive adults with prediabetes to complete a 2-week supervised MICT or HIIT plus behavioral counseling exercise intervention and objectively assessed free-living physical activity post-intervention. The Feeling Scale (FS) was used to assess the in-task effect. FS was measured in the middle of four, 1-min intervals in the HIIT condition, corresponding to ~20%, ~50%, ~75%, and ~85% of work out time. For the MICT condition, FS was assessed at similar exercise duration percentage times as HIIT. Accelerometer data evaluated MVPA at 1- and 6-month post-intervention. Results: 32 adults were included in the analyses. Pilot findings indicated in-task affect between the conditions did not predict changes in MVPA-Total from baseline to 1 and 6 months. For MVPA10+, in-task affect negatively predicted MVPA10+ over time in the MICT condition only. Conclusion: This study provides preliminary evidence that affect during MICT negatively predicts MVPA10+ over time, and that there is no difference of in-task affect's utility in predicting MVPA-Total between HIIT and MICT. Larger studies are required to confirm these findings.

Affective and Enjoyment Responses to Sprint Interval Training in Healthy Individuals: A Systematic Review and Meta-Analysis

Sprint interval training (SIT) is characterized by intensity of “all-out” effort and superior time-efficiency compared to traditional moderate-intensity continuous training (MICT) and has been proposed as one viable solution to address the commonly reported barrier of lack of time for physical activity. While substantial physiological benefits of participation in SIT have been well-documented, the psychological responses to SIT are less clear. No systematic review has been conducted thus far to respond to the assumption that its supramaximal intensity will induce adverse feelings. Therefore, the aim of the present study was to synthesize studies analyzing affective and enjoyment responses to SIT and to compare the responses to SIT with MICT and other high intensity interval training (HIIT) protocols with lower intensities. After searching relevant databases up until 22nd March 2021, twenty-five studies meeting the inclusion criteria were included in the present review. Random effect meta-analysis using the pooled data demonstrated that SIT induced similar post-exercise affective valences during the training compared to MICT and HIIT, but lower affective valences immediately post-exercise compared to MICT. Moreover, affective responses during SIT decreased to negative valences according to the results from most included studies, while low-volume SIT protocols with shorter sprint duration and repetitions induced more positive affective responses. Level of enjoyment after SIT were positive and were comparable to MICT or HIIT. Overall, the results from the existing literature indicate that SIT might cause unpleasant feelings during the training and be perceived less pleasurable than MICT immediately post training but could be a comparably enjoyable modality for healthy individuals in relation to MICT or HIIT, despite its supramaximal intensity. Low-volume SIT may be a realistic option for individuals seeking a time-efficient workout with comparable affective responses to MICT or HIIT.

Affecting Effects on Affect: The Impact of Protocol Permutations on Affective Responses to Sprint Interval Exercise; A Systematic Review and Meta-Analysis of Pooled Individual Participant Data

Responses to sprint interval exercise (SIE) are hypothesized to be perceived as unpleasant, but SIE protocols are diverse, and moderating effects of various SIE protocol parameters on affective responses are unknown. We performed a systematic search to identify studies (up to 01/05/2021) measuring affective valence using the Feeling Scale during acute SIE in healthy adults. Thirteen studies involving 18 unique trials and 316 unique participant (142 women and 174 men) affective responses to SIE were eligible for inclusion. We received individual participant data for all participants from all studies. All available end-of-sprint affect scores from each trial were combined in a linear mixed model with sprint duration, mode, intensity, recovery duration, familiarization and baseline affect included as covariates. Affective valence decreased significantly and proportionally with each additional sprint repetition, but this effect was modified by sprint duration: affect decreased more during 30 s (0.84 units/sprint; 95% CI: 0.74–0.93) and 15–20 s sprints (1.02 units/sprint; 95% CI: 0.93–1.10) compared with 5–6 s sprints (0.20 units/sprint; 95% CI: 0.18–0.22) (both p < 0.0001). Although the difference between 15–20 s and 30 s sprints was also significant (p = 0.02), the effect size was trivial (d = −0.12). We observed significant but trivial effects of mode, sprint intensity and pre-trial familiarization, whilst there was no significant effect of recovery duration. We conclude that affective valence declines during SIE, but the magnitude of the decrease for an overall SIE session strongly depends on the number and duration of sprints. This information can be applied by researchers to design SIE protocols that are less likely to be perceived as unpleasant in studies of real-world effectiveness.

Differences in Physiological and Perceptual Responses to High Intensity Interval Exercise Between Arm and Leg Cycling

This study compared changes in oxygen uptake (VO₂), heart rate (HR), blood lactate concentration (BLa), affective valence, and rating of perceived exertion (RPE) between sessions of high intensity interval exercise (HIIE) performed on the arm (ACE) and leg cycle ergometer (LCE). Twenty three active and non-obese men and women (age and BMI=24.7±5.8year and 24.8±3.4kg/m²) initially underwent graded exercise testing to determine VO₂max and peak power output (PPO) on both ergometers. Subsequently on two separate days, they performed 10 1min intervals of ACE or LCE at 75 %PPO separated by 1min of active recovery at 10 %PPO. Gas exchange data, HR, and perceptual responses were obtained continuously and blood samples were acquired pre- and post-exercise to assess the change in BLa. VO₂max and PPO on the LCE were significantly higher (p<0.001) than ACE (37.2±6.3 vs. 26.3±6.6ml/kg/min and 259.0±48.0 vs. 120.0±48.1W). Mean VO₂ (1.7±0.3 vs. 1.1±0.3L/min, d=2.3) and HR (149±14 vs. 131±17 b/min, d=2.1) were higher (p<0.001) in response to LCE vs. ACE as was BLa (7.6±2.6 vs. 5.3±2.5mM, d=2.3), yet there was no difference (p=0.12) in peak VO₂ or HR. Leg cycling elicited higher relative HR compared to ACE (81±5 vs. 75±7 %HRmax, p=0.01), although, there was no difference in relative VO₂ (63±6 vs. 60±8 %VO₂max, p=0.09) between modes. Affective valence was lower during LCE vs. ACE (p=0.003), although no differences in enjoyment (p=0.68) or RPE (p=0.59) were demonstrated. Overall, HIIE performed on the cycle ergometer elicits higher relative heart rate and blood lactate concentration and a more aversive affective valence, making these modes not interchangeable in terms of the acute physiological and perceptual response to interval based exercise.

Physiological and Psychological Responses to Three Distinct Exercise Training Regimens Performed in an Outdoor Setting: Acute and Delayed Response

The aim of this study was to compare the acute responses to three time-matched exercise regimens. Ten trained adults (age, maximum oxygen consumption (VO2max), and body mass index (BMI) = 25.9 ± 5.6 yr, 50.9 ± 5.4 mL·kg-1·min-1, and 22.1 ± 1.8 kg·m-2) completed sprint interval training (SIT) requiring 14 × 5 s efforts with 35 s of recovery, high-intensity interval training (HIIT) consisting of 18 × 15 s efforts at ~90% of peak heart rate (HRpeak) with 15 s of recovery, and vigorous continuous training (CT) consisting of 8.75 min at ~85 %HRpeak, in randomized order. Heart rate, blood lactate concentration, rating of perceived exertion, affective valence, and enjoyment were monitored. Moreover, indices of neuromuscular function, autonomic balance, diet, mental stress, incidental physical activity (PA), and sleep were measured 24 h after each session to analyze the magnitude of recovery. Both HIIT and CT exhibited a greater %HRpeak and time ≥ 90 %HRpeak than SIT (p < 0.05). Blood lactate and rating of perceived exertion were higher in response to SIT and HIIT vs. CT (p < 0.05); however, there were no differences in enjoyment (p > 0.05). No differences were exhibited in any variable assessed along 24 h post-exercise between conditions (p > 0.05). These data suggest that HIIT and CT accumulate the longest duration at near maximal intensities, which is considered a key factor to enhance VO2max.

Physical activity level and perceived exertion predict in-task affective valence to low-volume high-intensity interval exercise in adult males

Previous results reveal a decline in affective valence in response to progressive exercise in adults. However, this similar decline is not universally observed in response to high intensity interval exercise (HIIE), which may be due to its intermittent nature. The aim of the current study was to examine potential predictors of the in-task affective valence to low-volume HIIE (LV-HIIE; 10 × 60 s high-intensity intervals at 90% of maximal treadmill velocity interspersed by 60 s at 30% of maximal treadmill velocity). We analyzed data from 76 males (age and body mass index = 26.5 ± 4.4 yr and 27.3 ± 5.4 kg/m²) who had participated in previous investigations in our lab. Throughout each session, affective valence (Feeling Scale; + 5 to -5), rating of perceived exertion (RPE; Borg scale 6 to 20), and heart rate (HR) were measured. The predictors of in-task affective valence were analyzed during different phases of the LV-HIIE session (i.e. beginning, average of high-intensity intervals 1-3; middle, average of high-intensity intervals 4-7; and end, average of high-intensity intervals 8-10). Results showed a significant decline in affective valence (p < 0.001), increase in RPE (p < 0.001) and HR (p < 0.001) in response to LV-HIIE. Primary predictors of in-task affective valence to LV-HIIE were physical activity level and RPE (beginning, R² = 0.511, p < 0.001; middle, R² = 0.681, p < 0.001; end, R² = 0.742, p = 0.008). In conclusion, physical activity level and perceived exertion significantly predict the in-task affective valence to LV-HIIE in adult males.

Positive Affective and Enjoyment Responses to Four High-Intensity Interval Exercise Protocols

Several variables can be manipulated to compose high-intensity interval exercise (HIIE) protocols, and these different combinations may evoke different psychological responses (affect, enjoyment, mood, and perceived exertion). This study investigated psychological responses during four HIIE protocols. Following anthropometric measurements and two maximal exercise tests, 23 physically inactive adults (11 males [M_age = 25.6, SD = 4.8 years; M_{body mass} = 68.5, SD = 12.2 kg; M_height = 1.72, SD = 0.08 m] and 12 females [M_age = 25.0, SD = 3.5 years; M_{body mass} = 57.2, SD = 8.7 kg; M_height = 1.59, SD = 0.06 m]) performed four different types of HIIE on different days: (a) Long-interval HIIE (HIIE_L-10 × 60 seconds:60 seconds), (b) Short-interval HIIE (HIIE_S-2 blocks of 10 × 30 seconds:30 seconds with 120 seconds between blocks), (c) Repeated Sprint Training (19 × 6 seconds all out:40 seconds), and (d) Sprint Interval Training (4 × 30 seconds all-out efforts: 240 seconds). We used a final session to assess participants' HIIE preference. We recorded participant reports of affect, mood, and perceived exertion throughout protocols, and we recorded enjoyment after exercise session. Perceived exertion significantly increased across all HIIE protocols (p < .001), with higher values in the first quartile during Sprint Interval Training versus HIIE_L (p = .033). Affective response presented higher values pre-exercise and at the first quartile compared with all other moments (p < .001). Tension (p < .001) and depression (p = .013) decreased from pre- to post-exercise in all experimental conditions. At pre-exercise, female participants were tenser than males (p = .018), though males presented higher pre-exercise vigor scores than females (p = .023). Vigor increased over time for females (p = .022). Enjoyment did not vary between sexes or protocols. Participants expressed a higher preference for Repeated Sprint Training. HIIE protocols promoted positive psychological responses for physically inactive young adults, and exercise designs may modulate psychological responses.

Similar perceptual responses to reduced exertion high intensity interval training (REHIT) in adults differing in cardiorespiratory fitness

Reduced exertion high intensity interval training (REHIT) is an extremely low-volume approach of sprint interval exercise (SIE) that increases maximal oxygen uptake (VO₂max) and reduces body fat. However, there are concerns regarding implementation of SIE including REHIT in untrained populations due to generation of supramaximal power outputs and potential feelings of displeasure. This study examined perceptual responses to a single REHIT session in adults with above (n = 43, VO₂max = 41 ± 6 mL/kg/min) and below average VO₂max (n = 42, VO₂max = 33 ± 5 mL/kg/min). Initially, incremental exercise was completed to determine VO₂max. Subsequently, participants completed REHIT consisting of two 20 s "all-out" sprints at resistance equal to 5 % body mass. Rating of perceived exertion (RPE), affective valence, and physical activity enjoyment (PACES) were determined. Tolerance and preference to exercise intensity were also measured to examine if they moderated the responses. Compared to participants with below average VO₂max, those with above average VO₂max revealed similar change in affective valence (p = 0.86), RPE (p = 0.41), and enjoyment (p = 0.64) despite attaining significantly higher peak and mean power output in response to REHIT. The lowest value of affective valence ranged from 1.0-1.5, representing "fairly good." Overall, one session of REHIT elicits positive affective valence and similar pleasure:displeasure and enjoyment responses in individuals having diverse cardiorespiratory fitness, although we recommend that REHIT should be individualized for each client as greater frequency of aversive responses was shown in our participants with low fitness.

Comparison of perceptual responses between different upper-body sprint interval exercise protocols

This study examined the perceptual responses to various upper-body sprint interval exercise (SIE) protocols matched for total work and work/rest ratio. Fourteen active men (24 ± 4 years, BMI = 26.2 ± 2.7 kg/m², body fat = 11.5 ± 4.4%) participated in 3 all-out SIE protocols consisting of battling rope exercise: P10:30 (12 × 10-s bouts with 30-s recovery); P15:45 (8 × 15-s bouts with 45 s recovery); and P30:90 (4 × 30-s bouts with 90-s recovery). During exercise, affective valence (FS +5 to -5), arousal (FAS 1-6), rating of perceived exertion (RPE 6-20), and heart rate (HR) were assessed. Post-exercise, enjoyment, self-efficacy, and intentions were measured. Results revealed a significant decline in FS (p = .02; partial eta squared [η²_p] = 0.27) and a progressive increase in FAS (p = .001; η²_p = 0.86), RPE (p = .001; η²_p = 0.88), and HR (p = .001; η²_p = 0.94), but no protocol X time interaction. Affective valence reached a nadir at values equal to -0.36 ± 3.41 (Cohen's d = -0.49), -0.43 ± 3.75 (Cohen's d = -0.44), and - 0.93 ± 3.49 (Cohen's d = -0.56) in response to P10:30, P15:45, and P30:90, respectively. There were no differences between protocols for enjoyment, intention, or self-efficacy. A negative relationship exhibited between FS and RPE was moderated by participants' tolerance of exercise intensity (β = 1.84, p < .05). Further, the association between FS and future intention was mediated by self-efficacy. Overall, upper-body SIE protocols exhibit similar perceptual responses when volume and work to rest ratio (1:3) are matched. Tolerance of exercise intensity may be used to predict changes in FS during SIE.

High-Intensity Interval Training in Cardiac Rehabilitation

Recently, high-intensity interval training (HIIT) has been recognized as a safe and effective alternative to moderate-intensity continuous training for older patients with cardiovascular disease (CVD) in cardiac rehabilitation settings in an effort to improve health outcomes. This brief review considers general principles and suggestions for prescription of HIIT for older patients with CVD, specific challenges pertaining to older adults, the physiologic mechanisms by which HIIT contributes to improvements in peak Vo₂, and the effects of HIIT on cardiovascular health in older patients with coronary artery disease and heart failure.

Does sex mediate the affective response to high intensity interval exercise?

High intensity interval exercise (HIIE) is identified as an alternative to moderate intensity continuous exercise (MICE) due to its similar effects on outcomes including maximal oxygen uptake and glycemic control. Nevertheless, its widespread implementation in adults is questioned because acute HIIE elicits more aversive responses (negative affective valence) than MICE which may make it impractical to perform long-term. Differences in muscle mass, fiber type, and substrate utilization exist between men and women that alter physiological responses which may cause differences in affective valence, yet the effect of sex on this outcome is unresolved. This study compared changes in affective valence between active men and women (mean age = 24.0 ± 4.8 yr) performing HIIE and sprint interval exercise (SIE) on a cycle ergometer. Affect (+5 to -5), rating of perceived exertion (RPE 1-10), and blood lactate concentration (BLa) were measured before and throughout exercise, and enjoyment was assessed post-exercise. Results showed that women exhibit more positive affect (p < .05) during HIIE and SIE than men (0.6-1.8 units higher values). In addition, women exhibited lower BLa (p = .003) than men during SIE (11.8 ± 2.4 mM vs. 14.9 ± 3.1 mM). In contrast, there was no effect of sex on RPE (p = .32 and p = .54) or enjoyment (p = .24 and p = .37) in response to HIIE or SIE. Practitioners should consider the sex of their clients when assessing change in affective valence induced by interval-based exercise.