A scoping review of the psychological responses to interval exercise: is interval exercise a viable alternative to traditional exercise?

Aquatic High-Intensity Interval Deep Water Running Influence on Cardiometabolic Health and Cognitive Psychological Responses in Women

PURPOSE

To investigate the effects of an 8-wk AHIIT-DWR intervention compared with land-based HIT training (LHIIT) on cardiometabolic health, cognitive, and psychological outcomes in inactive elderly women.

METHODS

Seventy inactive elderly women aged 60 yr or above were randomly assigned into two groups: AHIIT-DWR and LHIIT. The AHIIT-DWR group engaged in DWR sessions comprising 30 min of interval training, consisting of ten 2-min exercise bouts at 80%-90% of their maximal heart rate (HR max ), with 1-min active recovery at 70% HR max between bouts, for two sessions per week, for 8 wk. The LHIIT group performed treadmill running at the same intensity.

RESULTS

Both groups showed similar cardiovascular fitness, maximal aerobic capacity (V̇O 2max ), HR max , and RER improvement ( P > 0.05), whereas AHIIT-DWR showed a significant improvement in aerobic capacity minute ventilation (V̇E), metabolic equivalents (METs), and O 2 pulse ( P < 0.05) over the 8-wk intervention. Both AHIIT-DWR and LHIIT significantly decreased triglycerides, total cholesterol, HDL, and LDL postintervention ( P < 0.05). No significant group differences were observed for cognitive function assessed by MMSE and MOCA ( P > 0.05). Both groups showed similar enjoyment levels, self-efficacy scores, and high adherence rates (>90%).

CONCLUSIONS

Our study suggests that AHIIT-DWR can elicit a similar improvement in cardiorespiratory health, metabolic blood markers, cognitive function assessed by MMSE and MOCA, and psychological responses as LHIIT in inactive elderly women.

Effects and mechanisms of supramaximal high-intensity interval training on extrapulmonary manifestations in people with and without chronic obstructive pulmonary disease (COPD-HIIT): study protocol for a multi-centre, randomized controlled trial

BACKGROUND

Beyond being a pulmonary disease, chronic obstructive pulmonary disease (COPD) presents with extrapulmonary manifestations including reduced cognitive, cardiovascular, and muscle function. While exercise training is the cornerstone in the non-pharmacological treatment of COPD, there is a need for new exercise training methods due to suboptimal adaptations when following traditional exercise guidelines, often applying moderate-intensity continuous training (MICT). In people with COPD, short-duration high-intensity interval training (HIIT) holds the potential to induce a more optimal stimulus for training adaptations while circumventing the ventilatory burden often associated with MICT in people with COPD. We aim to determine the effects of supramaximal HIIT and MICT on extrapulmonary manifestations in people with COPD compared to matched healthy controls.

METHODS

COPD-HIIT is a prospective, multi-centre, randomized, controlled trial with blinded assessors and data analysts, employing a parallel-group designed trial. In phase 1, we will investigate the effects and mechanisms of a 12-week intervention of supramaximal HIIT compared to MICT in people with COPD (n = 92) and matched healthy controls (n = 70). Participants will perform watt-based cycling two to three times weekly. In phase 2, we will determine how exercise training and inflammation impact the trajectories of neurodegeneration, in people with COPD, over 24 months. In addition to the 92 participants with COPD performing HIIT or MICT, a usual care group (n = 46) is included in phase 2. In both phases, the primary outcomes are a change from baseline in cognitive function, cardiorespiratory fitness, and muscle power. Key secondary outcomes include change from baseline exercise tolerance, brain structure, and function measured by MRI, neuroinflammation measured by PET/CT, systemic inflammation, and intramuscular adaptations. Feasibility of the interventions will be comprehensively investigated.

DISCUSSION

The COPD-HIIT trial will determine the effects of supramaximal HIIT compared to MICT in people with COPD and healthy controls. We will provide evidence for a novel exercise modality that might overcome the barriers associated with MICT in people with COPD. We will also shed light on the impact of exercise at different intensities to reduce neurodegeneration. The goal of the COPD-HIIT trial is to improve the treatment of extrapulmonary manifestations of the disease.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT06068322. Prospectively registered on 2023-09-28.

One-HIIT wonder: Can music make high-intensity interval training more pleasant?

The use of music as an aid to recovery during and after exercise is an area of growing scientific interest. We investigated the effects of in-task, asynchronous music and respite-active music (i.e., music used for active recovery in between high-intensity exercise bouts) on a range of psychological, psychophysical and psychophysiological outcomes. Participants (N = 28; 14 females) made five laboratory visits for: (a) pre-test/familiarisation; (b) fast-tempo music during supramaximal exercise bouts and medium-tempo music during active-recovery periods; (c) fast-tempo music during exercise and no music during recovery; (d) no music during exercise and medium-tempo music during recovery; and (e) a no-music (throughout) control. A cycle ergometer-based HIIT protocol comprising 6 × 60-s bouts at 100% Wmax with 75-s active recovery was administered. Measures were taken at the end of supramaximal bouts and active recovery periods (RPE, state attention, core affect, state motivation), then upon cessation of the protocol (remembered pleasure and exercise enjoyment). Heart rate and heart rate variability (HRV) measures were taken throughout. The music manipulations only had an effect on state motivation, which was higher (p = 0.036) in the fast tempo-medium tempo condition compared to no-music control (Cohen's d = 0.49), and the SDNN component of HRV, which was lower (p = 0.007) in the fast-tempo-no-music condition compared to control (Cohen's d = 0.32). Collectively, the present findings do not support any of the study hypotheses regarding the music-related manipulations, and do not concur with the findings of related studies (e.g., Karageorghis et al., 2021). The unexpected results are discussed with reference to extant theory, and recommendations are offered in regard to music-related applications.

Does yoga improve sexual function? A systematic review and meta-analysis of randomized clinical trials

BACKGROUND

Yoga practice can increase blood flow in the genital area, increase muscular strength, and improve body perception, which is related to sexual function. This study aimed to summarize the available evidence about the effects of yoga on sexual function in adults.

METHODS

Systematic searches of five databases were conducted from inception to April 28, with the last update on September 28, 2023. Randomized clinical trials (RCTs) that compared yoga with nonintervention control groups on sexual function in adults. Risk of bias and certainty of evidence were assessed by the Cochrane risk of bias tool 2, and the GRADE approach, respectively. Summary effect size measures were calculated using a random-effects model estimation and are reported as standardized mean differences and 95% confidence intervals. Reporting followed the PRISMA guidelines.

RESULTS

Ten RCTs that comprised 730 adults (range mean age, 26.64-68.2 years; 680 [93.2 %] women) were included. For the primary outcome, yoga intervention was associated with a significant small improvement in sexual function (-0.31; -0.47 to -0.15, p = 0.0002), with some concerns about risk of bias in nine RCTs (90%) and low-certainty evidence. Subgroup analyses revealed that yoga interventions performed by women (-0.36; -0.52 to -0.21, p < 0.00001), healthy individuals (-0.38; -0.59 to -0.16, p = 0.0006), or middle-aged individuals (-0.44; -0.63 to -0.25, p < 00001) significantly improved sexual function compared with control groups.

CONCLUSION

Yoga was associated with a small improvement in sexual function compared with nonintervention control groups in adults. However, high-quality, larger RCTs are required to draw more definitive conclusions.

HIIT at Home: Enhancing Cardiorespiratory Fitness in Older Adults-A Randomized Controlled Trial

BACKGROUND

This study aimed to investigate the effectiveness of a 6-month home-based high-intensity interval training (HIIT) intervention to improve peak oxygen consumption (V̇O2peak) and lactate threshold (LT) in older adults.

METHODS

Two hundred thirty-three healthy older adults (60-84 years; 54% females) were randomly assigned to either 6-month, thrice-weekly home-based HIIT (once-weekly circuit training and twice-weekly interval training) or a passive control group. Exercise sessions were monitored using a Polar watch and a logbook for objective and subjective data, respectively, and guided by a personal coach. The outcomes were assessed using a modified Balke protocol combining V̇O2peak and LT measures. General linear regression models assessed between-group differences in change and within-group changes for each outcome.

RESULTS

There was a significant between-group difference in the pre-to-post change in V̇O2peak (difference: 1.8 [1.2; 2.3] mL/kg/min; exercise: +1.4 [1.0; 1.7] mL/kg/min [~5%]; control: -0.4 [-0.8; -0.0] mL/kg/min [approximately -1.5%]; effect size [ES]: 0.35). Compared with controls, the exercise group had lower blood lactate concentration (-0.7 [-0.9; -0.4] mmol/L, ES: 0.61), % of peak heart rate (-4.4 [-5.7; -3.0], ES: 0.64), and % of V̇O2peak (-4.5 [-6.1; -2.9], ES: 0.60) at the intensity corresponding to preintervention LT and achieved a higher treadmill stage (% incline) at LT (0.6 [0.3; 0.8]; ES: 0.47), following the intervention.

CONCLUSION

This study highlights the effectiveness of a home-based HIIT intervention as an accessible and equipment-minimal strategy to induce clinically meaningful improvements in cardiorespiratory fitness in older adults. Over 6 months, the exercise group showed larger improvements in all outcomes compared with the control group. Notably, the LT outcome exhibited a more pronounced magnitude of change than V̇O2peak.

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.

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.

Enjoyment and Affective Responses to Moderate and High-Intensity Exercise: A Randomized Controlled Trial in Individuals with Subsyndromal PTSD

This crossover randomized controlled trial examined the acute psychological effects of a bout of moderate-intensity continuous aerobic exercise (MICE) and a bout of high-intensity functional exercise (HIFE), relative to a no-exercise sedentary control (SED), in participants (N = 21; 15 f; 24.7 ± 9.3 years) with subsyndromal post-traumatic stress disorder (PTSD). Affective state (Energy, Tiredness, Tension, Calmness) was assessed before (Pre), immediately after (Post 0), 20-min after (Post 20), and 40-min after (Post 40) each condition. Affective valence was assessed during each condition, and exercise enjoyment was assessed at Post 0. Enjoyment was significantly greater following HIFE and MICE relative to SED. Energy was significantly increased Post 0 HIFE and MICE but decreased Post 0 SED. Tension was reduced following all conditions and was significantly lower at Post 40 relative to Pre for HIFE, MICE, and SED. Tiredness was significantly reduced at Post 40 relative to Pre following MICE only, while Calmness was significantly lower at Post 40 relative to Pre following MICE and SED. Overall, both exercise conditions were enjoyed to a greater extent than the control, but MICE may provide greater psychological benefits with respect to Calmness and Tiredness. This study is among the first to assess acute changes in affective states relative to various exercise modes in individuals living with subsyndromal PTSD.

Exercise in the workplace: examining the receptivity of practical and time-efficient stair-climbing "exercise snacks"

In the workplace, people are often sedentary for prolonged time and do not regularly engage in physical activity-two factors independently linked to premature morbidity and mortality. This study aimed to determine the receptivity of incorporating practical stair-climbing "exercise snacks" (Snacks; three isolated bouts of ascending 53-60 stairs performed sporadically throughout the day) into workplace settings compared to more traditional high-intensity interval training (HIIT; performed as three bouts of 53-60 stairs within a structured HIIT workout) and to explore if these exercise strategies could influence sedentary and physical activity behaviour. Fourteen participants (12 women; Mage = 38.9 ± 10.2 years) completed two supervised exercise trials (Snacks and HIIT) followed by 1 week participating in either form of exercise in their workplace. Ratings of perceived exertion (RPE), affective valence, enjoyment, and self-efficacy were measured at the supervised exercise sessions. During the follow-up period, sedentary behaviour and physical activity were measured with an accelerometer. Affective valence was more positive (p = 0.03; η2 p = 0.21) and there was a lower rise in RPE (p = 0.01; η2 p = 0.29) during Snacks than HIIT. Post-exercise enjoyment of, and self-efficacy towards, Snacks and HIIT were high and similar (ps > 0.05). After the supervised trials, 10/14 of the participants preferred Snacks and 4/14 preferred HIIT (p = 0.18). On days when participants chose to perform either exercise modality, the average number of sit-to-stands in a 24 h period was increased (48.3 ± 8.7 to 52.8 ± 7.8; p = 0.03; Hedge's g = 0.73) and moderate-to-vigorous physical activity tended to increase (21.9 ± 18.2 to 38.1 ± 22.1 min; p = 0.06; Hedge's g = 0.60) compared to days when they chose not to exercise. Stair-climbing exercise snacks may be an attractive approach to implement in the workplace setting and has potential to positively impact sedentary behaviour and physical activity metrics.

Effects of tempo of self-selected music on isokinetic strength performance and psychological outcomes

Substantial research has supported using musical stimuli as an ergogenic aid before and during various forms of exercise. Researchers have demonstrated that music shifts attention from associative to dissociative, decreases perceived effort and discomfort, and increases arousal and pleasantness in longer-duration, low-to-moderate-intensity exercises. Strength training is shorter in duration and higher in intensity than aerobic or muscular endurance training. Limited research has examined the effects of music on strength performance and psychological outcomes. Therefore, the purpose of this study was to investigate the effects of the tempo of self-selected music on isokinetic knee extension and flexion performance, effort, discomfort, attention, arousal, and pleasantness in resistance-trained young adults. Thirty resistance-trained college-aged adults completed three exercise testing sessions. In a randomized, counterbalanced order, a repeated measures design was used to expose the participants to three conditions (fast music, slow music, and no music). The Biodex isokinetic dynamometer and standardized psychological Likert-style scales were used to measure concentric maximum effort knee extension and flexion torque at 60°/s and psychological variables, respectively. This study found that music improves knee extension torque but not knee flexion in resistance-trained young adults. In addition, music or the tempo of music did not influence any psychological outcomes during isokinetic strength testing. Therefore, listening to music is not detrimental to performance or psychological outcomes, but this study provides minimal support for music's use as an ergogenic aid during strengthening 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.

A Narrative Literature Review on the Role of Exercise Training in Managing Type 1 and Type 2 Diabetes Mellitus

Diabetes mellitus (DM) is a metabolic disease characterized by chronic hyperglycemia associated with impaired carbohydrate, lipid, and protein metabolism, with concomitant absence of insulin secretion or reduced sensitivity to its metabolic effects. Patients with diabetes mellitus have a 30% more risk of developing heart failure and cardiovascular disease compared to healthy people. Heart and cardiovascular problems are the first cause of death worldwide and the main complications which lead to high healthcare costs. Such complications can be delayed or avoided by taking prescribed medications in conjunction with a healthy lifestyle (i.e., diet and physical activity). The American College of Sports Medicine and the American Diabetes Association recommend that diabetic people reduce total sedentary time by incorporating physical activity into their weekly routine. This narrative literature review aims to summarize and present the main guidelines, pre-exercise cardiovascular screening recommendations, and considerations for patients with diabetes and comorbidities who are planning to participate in physical activity programs.

Can In-Task Affect During Interval and Continuous Exercise Predict 12-Month Physical Activity Behavior? Findings from a Randomized Trial

BACKGROUND

In-task affective responses to moderate-intensity continuous exercise training (MICT) have been shown to predict future physical activity behavior. However, limited research has investigated whether this affect-behavior relationship is similar for high-intensity interval training (HIIT) and whether it holds true over the longer term. This study aims to determine (1) if in-task affect during 2 weeks of supervised MICT and HIIT predicted changes to unsupervised moderate-to-vigorous physical activity (MVPA) behavior 12 months post-intervention and (2) if this predictive relationship was moderated by exercise type (MICT vs. HIIT).

METHOD

Ninety-nine adults (69.7% female; 50.9 ± 9.4 years) who were low active and overweight were randomized to 2 weeks of exercise training of MICT (n = 52) or HIIT (n = 47), followed by 12 months of accelerometry-assessed free-living MVPA.

RESULTS

The pooled moderation model was not significant, F(3, 94) = 2.54, p = .07 (R2 = 0.085), with a non-significant group by affect interaction (p = .06). The conditional effect for MICT was significant (B = 17.27, t = 2.17, p = .03), suggesting that 12-month change in MVPA increased by 17.27 min/week for every one-point increase in in-task affect. The conditional effect for HIIT was not significant (p = .85), suggesting that in-task affect was not predictive of 12-month change in MVPA.

CONCLUSION

The current findings raise important questions about whether the affect-behavior relationship may vary depending on exercise type. For HIIT-based exercise in particular, additional psychological constructs beyond in-task affect should be considered when attempting to predict future physical activity behavior.

"I just had the feeling that the interval training is more beneficial": young adults' subjective experiences of physical fitness and the role of training modes

Objective

Compelling evidence has shown that high-intensity interval training (HIIT) is associated with substantial increases in physical fitness. However, little is known about whether and how individuals experience these adaptations over time. The purpose of this study is, therefore, to explore how physically inactive young adults subjectively experience physical fitness and its development as they start to exercise and how these experiences relate to different intensity domains (i.e., moderate and severe) as well as to training modes [i.e., HIIT and moderate intensity continuous training (MICT)] and their sequential administration (i.e., HIIT-MICT and MICT-HIIT).

Methods

Thirty-one inactive participants completed a 15-week two-period sequential exercise intervention in which they first trained for six weeks in a HIIT or a MICT group and subsequently switched training modes. Interviews using the biographical mapping method were conducted at the end of the intervention to assess participants' exercise- and fitness-related experiences over the past weeks. To assess experiential patterns, we conducted a reflexive thematic analysis.

Results

We developed three themes that represent the temporal and processual character of starting to exercise after a prolonged period of inactivity: (1) Inactive young adults are not all the same when starting to exercise; (2) Developing physical fitness is a multi-faceted and individual experience; and (3) Feeling physically fit (or not) fosters large-scale effects.

Conclusion

Our results show that, in retrospect, participants mostly deemed HIIT to be more effective than MICT. Our findings also emphasize that physical fitness is a complex and subjective experience that manifests in various ways over time. The idiosyncrasy of physical fitness experiences reiterates the necessity for individually tailored exercise prescriptions instead of one-size-fits-all approaches.

Combining exercise with cognitive training and vitamin D3 to improve functional brain connectivity (FBC) in older adults with mild cognitive impairment (MCI). Results from the SYNERGIC trial

Changes in functional brain connectivity (FBC) may indicate how lifestyle modifications can prevent the progression to dementia; FBC identifies areas that are spatially separate but temporally synchronized in their activation and is altered in those with mild cognitive impairment (MCI), a prodromal state between healthy cognitive aging and dementia. Participants with MCI were randomly assigned to one of five study arms. Three times per week for 20-weeks, participants performed 30-min of (control) cognitive training, followed by 60-min of (control) physical exercise. Additionally, a vitamin D₃ (10,000 IU/pill) or a placebo capsule was ingested three times per week for 20-weeks. Using the CONN toolbox, we measured FBC change (Post-Pre) across four statistical models that collapsed for and/or included some or all study arms. We conducted Pearson correlations between FBC change and changes in physical and cognitive functioning. Our sample included 120 participants (mean age: 73.89 ± 6.50). Compared to the pure control, physical exercise (model one; p-False Discovery Rate (FDR) < 0.01 & < 0.05) with cognitive training (model two; p-FDR =  < 0.001), and all three interventions combined (model four; p-FDR =  < 0.01) demonstrated an increase in FBC between regions of the Default-Mode Network (i.e., hippocampus and angular gyrus). After controlling for false discovery rate, there were no significant correlations between change in connectivity and change in cognitive or physical function. Physical exercise alone appears to be as efficacious as combined interventional strategies in altering FBC, but implications for behavioral outcomes remain unclear.

Effects of Exercise Intensity on Cardiometabolic Parameters of Ovariectomized Obese Mice

The aim of this study was to compare the effects of continuous-moderate vs. high-intensity interval aerobic training on cardiovascular and metabolic parameters in ovariectomized high-fat-fed mice. C57BL/6 female ovariectomized were divided into four groups (n=8): low-fat-fed sedentary (SLF); high-fat-fed sedentary (SHF); high-fat-fed moderate-intensity continuous trained (MICT-HF); and high-fat-fed high-intensity interval aerobic trained (HIIT-HF). The high-fat diet lasted 10 weeks. Ovariectomy was performed in the fourth week. The exercise training was carried out in the last four weeks of protocol. Fasting glycemia, oral glucose tolerance, arterial pressure, baroreflex sensitivity, and cardiovascular autonomic modulation were evaluated. Moderate-intensity continuous training prevented the increase in arterial pressure and promoted a reduction in HR at rest, associated with an improvement in the sympathovagal balance in MICT-HF vs. SHF. The high-intensity interval training reduced blood glucose and glucose intolerance in HIIT-HF vs. SHF and MICT-HF. In addition, it improved sympathovagal balance in HIIT-HF vs. SHF. Moderate-intensity continuous training was more effective in promoting cardiovascular benefits, while high-intensity interval training was more effective in promoting metabolic benefits.

Extraordinary claims in the literature on high-intensity interval training (HIIT): III. Critical analysis of four foundational arguments from an interdisciplinary lens

Kinesiology aspires to be an integrated, interdisciplinary field that studies human movement from multiple perspectives. However, the main societal deliverables of the field, namely exercise prescriptions and physical activity recommendations, still reflect fragmentation, placing more emphasis on physiological outcomes than on behavioral and other considerations. Recently, researchers have called for the introduction of High-Intensity Interval Training (HIIT) to the domain of public health, based on the argument that HIIT can maximize fitness and health benefits for a fraction of the time recommended by the prevailing model of physical activity in public-health guidelines. Here, we show that an unintended side-effect of arguments underpinning the implementation of HIIT in the domain of public health might have been the exacerbation of segmentation. To highlight the value of interdisciplinarity, four foundational claims in support of HIIT are critiqued by tapping into cognate literatures: (1) the primary reason people do not exercise is lack of time, (2) HIIT is relevant to public health, (3) HIIT is being proposed as merely another option, so there is no basis for controversy, and (4) HIIT is safe and well tolerated. These claims are contradicted by credible lines of evidence. To improve the accuracy and effectiveness of its public claims, kinesiology should remain committed to the ideals of integration and interdisciplinarity.

Does Exercise Modality Matter Affectively? Contrasting Type and Sequence of Moderate-Intensity Continuous Training Versus High-Intensity Interval Training in a Randomized Within-Subject Study

Over the past two decades, affective determinants of exercise behavior have received increasing attention in research on health promotion and prevention. To date, however, little is known about changes in affective exercise determinants during multi-week training programs in insufficiently active individuals. This applies in particular to the currently discussed advantages and disadvantages of high-intensity interval training (HIIT) compared with moderate-intensity continuous training (MICT) with regard to the affective experience of these two training types (e.g., reduced monotony vs. more aversive response during HIIT), which is important for exercise adherence. Referring to the Affect and Health Behavior Framework (AHBF), this within-subject study investigated changes in affective exercise determinants as a function of training type and sequence consisting of MICT and HIIT. Forty insufficiently active healthy adults (M _age = 27 ± 6 years; 72% women) underwent two 6-week training periods in a randomized sequence (MICT - HIIT vs. HIIT - MICT) within 15 weeks. Pre-post questionnaires and in-situ measurements, during and after a standardized vigorous-intensity continuous exercise session (VICE), were used to assess affective attitude, intrinsic motivation, in-task affective valence, as well as post-exercise enjoyment. These four affect-related constructs were collected before, between, and after the two training periods. Mixed models revealed a significant effect for training sequence (p = 0.011) - but not for training type (p = 0.045; non-significant after Bonferroni alpha adjustment) - on changes in in-task affective valence in favor of the MICT - HIIT sequence. Moreover, no significant training type or sequence effects were found for the constructs of reflective processing: exercise enjoyment, affective attitude, and intrinsic motivation. Therefore, individual-based training recommendations should consider the effects of variety and training sequence to develop tailored interventions that lead to more positive affective experiences - in particular during exercise - and promote the maintenance of exercise behavior in previously inactive individuals.

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.

High-intensity interval training in children and adolescents with special educational needs: a systematic review and narrative synthesis

BACKGROUND

High-intensity interval training (HIIT) has been promoted as a time-efficient exercise strategy to improve health and fitness in children and adolescents. However, there remains little consensus in the literature regarding its efficacy in children and adolescents with special educational needs (SEN). This study aimed to examine HIIT as a means of improving key health and fitness parameters in children and adolescents with SEN.

METHODS

A systematic search was conducted on eight databases (MEDLINE, Embase, SPORTDiscus, Web of Science, Scopus, PsycINFO, CINAHL, and Cochrane Library). Studies were eligible if they 1) included an HIIT protocol, 2) examined parameters related to both physical and mental aspects of health and fitness, and 3) examined children and adolescents with SEN aged 5-17 years.

RESULTS

Of the 1727 studies yielded by the database search, 13 (453 participants) were included and reviewed. We found that HIIT generally improved body composition, physical fitness, and cardiometabolic risk biomarkers across a spectrum of SEN (e.g., attention deficit hyperactivity disorder, cerebral palsy, developmental coordination disorder, and mental illness). Improvements in mental health and cognitive performance following HIIT have also been observed.

CONCLUSION

This review provides up-to-date evidence for HIIT as a viable exercise strategy for children and adolescents with SEN. Further research investigating the benefits of HIIT in a wider range of SEN populations is warranted.

TRIAL REGISTRATION

This study was registered in the International Prospective Register of Systematic Review (PROSPERO; registration number CRD42022352696).

Is There a Dose-Response Relationship between High-Intensity Interval Exercise (HIIE) Intensity and Affective Valence? Analysis of Three HIIE Sessions Performed with Different Amplitudes

The inverse relationship between exercise intensity and affective valence is well established for continuous exercise but not for high-intensity interval exercise (HIIE). The objective was to verify the dose-response relationship between exercise intensity and affective valence in HIIE sessions. Eleven young men underwent a vigorous-intensity continuous exercise (VICE) and three HIIE sessions at the same average intensity (70% of peak power-W_Peak) and duration (20 min) but with different amplitudes: 10 × [1 min at 90% W_Peak/1 min at 50% W_Peak]-HIIE-90/50; 10 × [1 min at 100% W_Peak/1 min at 40% W_Peak]-HIIE-100/40; 10 × [1 min at 110% W_Peak/1 min at 30% W_Peak]-HIIE-110/30. During the exercise sessions, psychophysiological variables were recorded (VO₂, VCO₂, heart rate, perceived exertion CR10, and Feeling Scale (FS)). Higher correlations were found between CR10 and FS for all conditions (VICE = -0.987; HIIE-90/50 = -0.873; HIIE-100/40 = -0.908; HIIE-110/30 = -0.948). Regarding the physiological variables, the %HR_Max presented moderate inverse correlations with FS for all exercise conditions (VICE = -0.867; HIIE-90/50 = -0.818; HIIE-100/40 = -0.837; HIIE-110/30 = -0.828) while the respiratory variables (%VO_2Peak and %VCO_2Peak) presented low-to-moderate correlations only for VICE, HIIE-90/50, and HIIE-100/40 (ranging from -0.523 to -0.805). Poor correlations were observed between the %VO_2Peak (r = -0.293) and %VCO_2Peak (r = -0.020) with FS. The results indicated that perceived exertion is more sensible than physiological variables to explain the intensity-affective valence relationship in HIIE sessions. RPE should be used for HIIE prescription with a focus on affect.

Experiencing good results promotes positive feelings to high-intensity exercise among young adults: A qualitative study

Introduction

From a public health perspective, it is important to gain more insight into how people can be motivated to maintain effective exercise routines. It is a common belief that moderate-intensity exercise is more pleasant and enjoyable than high-intensity training. This study aims to provide insight into (1) participants' expectations and preferences for training intensity prior to training, (2) how longer-term participation affect participants' experience of endurance training with continuous moderate-intensity training and high-intensity interval training.

Materials and methods

A total of 22 participants (14 women and eight men) between the ages of 21–30 volunteered for participation. Participants were randomized and divided into two equal groups. A total of 17 participants, nine women and eight men, completed the study. One group did moderate-intensity longer-lasting training and the other did high-intensity interval training. All participants completed three training sessions per week for 8 weeks. Semi-structured interviews were conducted with each participant before and after completing the training intervention. Data was analyzed using thematic analysis. This study is a part of a larger study evaluating and comparing the effects on endurance capacity of high-intensity interval training and moderate-intensity training. Physiological data are previously published.

Results

The results describe participants expectations prior to training, and how they experienced the actual training. The overall experience of training comprises several factors that work together. Both expectations and actual experiences (e.g., of physical pleasantness or unpleasantness, of positive or negative emotions, and of actual results from the training) contribute to the participants' overall experience of exercise.

Conclusion

The major finding is that improved physical fitness was a stronger motivator than feelings of pleasantness. Experiencing good results seemed to downplay feelings of unpleasantness and reinforce positive feelings toward exercise. Lack of results reinforce negative feelings toward exercise. Participants reported high-intensity exercise as more unpleasant and exhaustive, but the interval training group were more satisfied and experienced the training as more motivating.

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.

Chronic, acute and protocol-dependent effects of exercise on psycho-physiological health during long-term isolation and confinement

Exercise could prevent physical and psychological deteriorations, especially during pandemic times of lock-down scenarios and social isolation. But to meet both, the common exercise protocols require optimization based on holistic investigations and with respect to underlying processes. This study aimed to explore individual chronic and acute effects of continuous and interval running exercise on physical and cognitive performance, mood, and affect and underlying neurophysiological factors during a terrestrial simulated space mission. Six volunteers (three females) were isolated for 120 days. Accompanying exercise training consisted of a continuous and interval running protocol in a cross-over design. Incremental stage tests on a treadmill were done frequently to test physical performance. Actigraphy was used to monitor physical activity level. Cognitive performance, mood (MoodMeter®), affect (PANAS), brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF-1), vascular-endothelial growth factor (VEGF), and saliva cortisol were investigated prior to, four times during, and after isolation, pre- and post-exercise on two separate days, respectively. As a chronic effect, physical performance increased (and IGF-1 tended) in the course of isolation and training until the end of isolation. Subjective mood and affect state, as well as cognitive performance, basal BDNF and VEGF levels, were well-preserved across the intervention. No acute effects of exercise were detected, besides slower reaction time after exercise in two out of nine cognitive tests, testing sensorimotor speed and memory of complex figures. Consistently higher basal IGF-1 concentrations and faster reaction time in the psychomotor vigilance test were found for the continuous compared to the interval running protocol. The results suggest that 120 days of isolation and confinement can be undergone without cognitive and mental deteriorations. Regular, individual aerobic running training supporting physical fitness is hypothesized to play an important role in this regard. Continuous running exercise seems to trigger higher IGF-1 levels and vigilance compared to interval running. Systematic and prolonged investigations and larger sample size are required to follow up on exercise-protocol specific differences in order to optimize the exercise intervention for long-term psycho-physiological health and well-being.

Psychological Adaptations to High-Intensity Interval Training in Overweight and Obese Adults: A Topical Review

Regular exercise has been reported as a fundamental piece of the management and treatment puzzle of obesity, playing a vital role in numerous psychological indicators. However, it is unclear whether high-intensity interval training (HIIT) can improve critical psychological health markers such as adherence, exercise enjoyment, affective responses, health-related quality of life, anxiety, and depression in overweight and obese adults. The purpose of this topical review was to catalogue studies investigating the psychological responses to HIIT in order to identify what psychological outcomes have been assessed, the research methods used, and the results. The inclusion/exclusion criteria were met by 25 published articles investigating either a traditional, single-component (84%) or a hybrid-type, multi-component (16%) HIIT protocol and involving 930 participants with overweight/obesity. The present topical review on HIIT-induced psychological adaptations shows that this popular exercise mode, but also demanding for the masses, can meaningfully increase the vast majority of the selected mental health-related indices. These improvements seem to be equal if not greater than those observed for moderate-intensity continuous training in overweight and obese adults. However, further research is needed in this area, focusing on the potential mechanisms behind positive alterations in various psychological health parameters through larger samples and high-quality randomized controlled trials.

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.

Systematic Review Registration

[https://www.crd.york.ac.uk/PROSPERO], Identifier [CRD42021284898].

Using Bodyweight as Resistance Can Be a Promising Avenue to Promote Interval Training: Enjoyment Comparisons to Treadmill-Based Protocols

Purpose: Even though multiple training methods appear to be effective to improve cardiorespiratory fitness, they also need to be perceived as tolerable or enjoyable by exercisers to maximize long-term behavioral maintenance. Therefore, the purpose of the current study was to compare perceived enjoyment between whole-body interval training (SIT-WB), treadmill-based interval training (SIT-T) and moderate-intensity continuous training (MICT). Method: Forty-one healthy adult men (age: 23.7 ± 0.7 years, height: 1.79 ± 0.01 m, body mass: 78.5 ± 1.7 kg; VO_2max: 46.7 ± 7.3 ml.kg^-1.min^-1) were randomly assigned to SIT-WB, SIT-T, or MICT and underwent 16 weeks of training (3x/w). SIT-WB and SIT-T completed eight 20 s bouts interspersed by 10 s passive recovery, differing as to the exercise mode performed (i.e., calisthenics exercises and treadmill running, respectively) whereas MICT participants ran for 30 min at an intensity below the second ventilatory threshold. Perceived enjoyment was assessed 10 min post-exercise at weeks 1, 5, 9, 13, and 16, using the Physical Activity Enjoyment Scale. Results: Compliance was high (~90%) across all three training groups (p = .803). All training modes were rated as enjoyable and no significant within- (F_{(4, 152)} = 1.132, p = .344) or between-group (F_{(2, 38)} = 0.662, p = .521) differences were found during the intervention period. Conclusions: These results suggest that SIT-WB can be employed as an enjoyable low-cost alternative to traditional treadmill-based SIT and MICT for up to 16 weeks.

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.

Alternating high-intensity interval training and continuous training is efficacious in improving cardiometabolic health in obese middle-aged men

Background

High-intensity interval training (HIIT) or moderate-intensity continuous training (MICT) alone has been shown to improve metabolic health, but the effects of alternating the two training approaches as often practiced in real life remained unclear.

Purpose

To examine the effects of HIIT or MICT alone or alternating HIIT-MICT on cardiometabolic responses in inactive obese middle-aged men.

Methods

Forty-two participants (age: 42 ± 5 y; BMI: 26.3 ± 2.1 kg m⁻²) were randomly assigned to four groups: HIIT (12 x 1-min running bouts at 80–90% HR_max interspersed with 1-min active recovery at 50% HR_max), MICT (40-min brisk walk at 65–70% HR_max), alternating HIIT-MICT or a non-exercise control group (CON). Exercise sessions were conducted three times per week for 16 weeks. Maximal oxygen uptake (VO_2max), body composition (by bioelectrical impedance analysis), blood pressure, fasting blood glucose, insulin resistance (HOMA-IR) and lipid profile were assessed at baseline and after the 16-week intervention. Enjoyment and self-efficacy were also assessed at the end of intervention.

Results

All exercise groups showed a similar VO_2max increase of ∼15% (HIIT: 34.3 ± 4.4 vs 39.1 ± 5.4; MICT: 34.9 ± 5.0 vs 39.4 ± 7.2; and alternating HIIT-MICT: 34.4 ± 5.0 vs 40.3 ± 4.6 mL kg⁻¹min⁻¹) compared to baseline and CON (all p < 0.05). Weight, BMI, % fat and waist circumference also showed similar reductions in all exercise groups compared to baseline and CON (all p < 0.05). No significant group difference was observed for all blood markers. Compared to baseline, total cholesterol decreased after HIIT-MICT, while HIIT significantly decreased fasting insulin level and improved insulin resistance (p < 0.05). Enjoyment, self-efficacy and adherence were similar among all exercise groups.

Conclusion

HIIT or MICT alone or alternating HIIT-MICT similarly improve cardiovascular fitness and body composition in obese middle-aged men despite differences in total training volume and time commitment.

When It HIITs, You Feel No Pain: Psychological and Psychophysiological Effects of Respite-Active Music in High-Intensity Interval Training

The authors investigated the effects of respite-active music (i.e., music used for active recovery in between high-intensity exercise bouts) on psychological and psychophysiological outcomes. Participants (N = 24) made four laboratory visits for a habituation, medium- and fast-tempo music conditions, and a no-music control. A high-intensity interval-training protocol comprising 8 × 60-s exercise bouts at 100% Wmax with 90-s active recovery was administered. Measures were taken at the end of exercise bouts and recovery periods (rating of perceived exertion [RPE], state attention, and core affect) and then upon cessation of the protocol (enjoyment and remembered pleasure). Heart rate was measured throughout. Medium-tempo music enhanced affective valence during exercise and recovery, while both music conditions increased dissociation (only during recovery), enjoyment, and remembered pleasure relative to control. Medium-tempo music lowered RPE relative to control, but the heart rate results were inconclusive. As predicted, medium-tempo music, in particular, had a meaningful effect on a range of psychological outcomes.

Efficacy of high-intensity interval- or continuous aerobic-training on insulin resistance and muscle function in adults with metabolic syndrome: a clinical trial

PURPOSE

We carried out a randomized, clinical trial in adults of both sexes with metabolic syndrome (MS) to assess the efficacy of high-intensity, low-volume interval training (HIIT) compared to moderate-intensity continuous training (MICT) on insulin resistance (IR), muscle mass, muscle activation, and serum musclin.

METHODS

Fasting glycemia, insulinemia, and glycated haemoglobin were determined by conventional methods, IR by Homeostatic model assessment (HOMA), lean mass by Dual-Energy X-ray Absorptiometry, muscle activation through carnosine by Proton Magnetic Resonance Spectroscopy, and musclin by Enzyme-Linked ImmunoSorbent Assay before and after a supervised, three-times/week, 12-week treadmill programme. HIIT (n = 29) consisted of six intervals with one-minute, high-intensity phases at 90% of peak oxygen consumption (VO_2peak). MICT (n = 31) trained at 60% of VO_2peak for 30 min.

RESULTS

Patients had a mean age of 50.8 ± 6.0 years, body mass index of 30.6 ± 4.0 kg/m², and VO_2peak of 29.0 ± 6.3 mL.kg^-1.min^-1. Compared to MICT, HIIT was not superior at reducing Ln HOMA-IR (adjusted mean difference: 0.083 [95%CI - 0.092 to 0.257]), carnosine or musclin or at increasing thigh lean mass. HIIT increased carnosine by 0.66 mmol/kg.ww (95% CI 0.08-1.24) after intervention. Both interventions reduced IR, body fat percentage and increased total lean mass/height² and VO_2peak. Musclin showed a non-significant reduction with a small effect size after both interventions.

CONCLUSION

Compared to MICT, HIIT is not superior at reducing IR, carnosine or musclin or at increasing skeletal muscle mass in adults with MS. Both training types improved IR, muscle mass and body composition. NCT03087721, March 22nd, 2017.

TRIAL REGISTRATION NUMBER

NCT03087721. Registered March 22nd, 2017.

Evidence-based vs. social media based high-intensity interval training protocols: Physiological and perceptual responses

OBJECTIVE

High intensity interval training (HIIT) is a time-efficient exercise modality to improve cardiorespiratory fitness, and has recently been popularised by social media influencers. However, little is known regarding acute physiological and perceptual responses to these online protocols compared to HIIT protocols used within research. The aim was to investigate acute physiological, perceptual and motivational responses to two HIIT protocols popular on social media, and compare these to two evidence-based protocols.

METHODS

Twenty-seven recreationally active (>1 exercise session /week) participants (Age: 22±3y, BMI: 24.3±2.4) completed a randomised cross-over study, whereby each participant completed four HIIT protocols, two already established in research (Ergo-60:60 (cycling 10x60s at 100%Wmaxwith 60s rest), BW-60:60 (body-weight exercises 10x60swith 60s rest)) and two promoted on social media (SM-20:10 (body-weight exercises 20x20swith 10s rest) and SM-40:20 (body-weight exercises 15x40s with 20s rest)). Blood lactate, heart rate (HR), feeling scale (FS), felt arousal scale (FSA), enjoyment and perceived competence were measured in response to each protocol.

RESULTS

Significant differences were observed between BW-60:60 and SM-20:10 for the proportion of intervals meeting the ACSM high-intensity exercise criterion (>80% of HRmax) (BW-60:60 93±10%, SM-20:10 74±20%, P = 0.039) and change in lactate (BW-60:60 +7.8±3.7mmol/L, SM-20:10 +5.5±2.6mmol/L, P = 0.001). The percentage of time spent above the criterion HR was also significantly lower in SM-20:10 compared to all other protocols (Ergo-60:60 13.9±4.9min, BW-60:60 13.5±3.5min, SM-40:20 12.1±2.4min, SM-20:10 7.7±3.1, P<0.05). No differences were observed in lowest reported FS between protocols (P = 0.268), but FS decreased linearly throughout Ergo-60:60 and BW-60:60 (first vs. last interval P<0.05), but not in SM-20:10 or SM-40:20 (P>0.05). Enjoyment was higher upon completion of BW-60:60 compared to Ergo-60:60 and SM-40:20 (P<0.05).

CONCLUSIONS

This study shows that HIIT protocols available on social media offer an interesting real-world alternative for promoting exercise participation. Future studies should continue to investigate these highly popular and practical HIIT protocols.

Does Becoming Fit Mean Feeling (f)it? A Comparison of Physiological and Experiential Fitness Data From the iReAct Study

Regular exercise fosters fitness-enhancing benefits. We assume that exercise interventions become successful and sustainable if physiological benefits of exercise are also subjectively perceivable. The goal of this study was to examine how young inactive adults physiologically respond to an exercise intervention and how those responses are subjectively experienced. Furthermore, we aimed to assess whether the sequence of two distinct endurance-based exercise modes has an impact on physiological and subjectively experienced physical fitness. Thirty-one young inactive adults were assessed for this substudy of the larger iReAct study. Participants were randomly assigned to a high-intensity interval training (HIIT) or a moderate-intensity continuous training (MICT) group for 6 weeks and subsequently switched groups for a second training period. Physiological fitness data was collected at baseline, follow-up I, and follow-up II using a graded cardiopulmonary exercise test. Subjectively reconstructed (i.e., retrospective constructions) experiences relating to physical fitness were assessed at follow-up II using a biographical mapping method. A repeated-measures one-way ANOVA on each training group was performed to see whether physiological and subjectively experienced fitness differed across training periods. The rate of change between all variables was calculated for the first and the second training period in order to compare the agreement between physiological and subjective fitness improvements. Participants increased their fitness across the intervention period both physiologically and subjectively. However, the rate of change depended on the sequence of the two training modes. While VO_2max increased significantly in both training periods in the MICT-HIIT sequence, a significant increase in VO_2max in the HIIT-MICT sequence was only observed in the HIIT period. Participants similarly perceived those increases subjectively in their exercise-related physical fitness, although they experienced a significant decrease in the second period of the HIIT-MICT sequence. For subjectively perceived physical fitness relating to everyday activities, significant increases were only observed for the first period of the MICT-HIIT sequence. Young inactive adults can improve both their physiological and their subjectively perceived fitness through regular exercise. However, exercise modes and their sequence can make a substantial difference regarding measured and perceived physical fitness. Additionally, despite a favorable tendency toward HIIT over MICT, inter- and intra-individual variability, particularly in the subjective experiences of fitness, reiterates the necessity of individualized approaches to exercise.

Acute affective responses to high-intensity interval exercise: Implications on the use of different stimulus-recovery amplitudes

The effect of high-intensity interval exercise (HIIE) on affective responses is unclear due to the several variables of HIIE, which may be minimized by using derived variables (e.g. amplitude). The amplitude reflects the difference between stimulus and recovery intensities, being more representative of the physiological changes than central tendency variables such as average intensity. This study aimed to compare the affective responses in HIIE sessions in different amplitudes with a vigorous-intensity continuous exercise (VICE) session. Eleven participants completed five sessions. The peak oxygen consumption (VO_2Peak) and peak power (W_peak) were measured. Participants performed one VICE and three HIIE sessions (10x[1min-90%W_Peak/1min-50%W_Peak]; 10x[1min-100%W_Peak/1min-40%W_Peak]; and 10x[1min-110%W_Peak/1min-40%W_Peak]). The exercise sessions were performed at the same average intensity (70%W_Peak) and duration (20 min). The Feeling Scale (FS) was applied in each minute throughout the exercise sessions. Regarding the FS responses, a two-way repeated-measures ANOVA showed no significant interaction for FS (P=0.093) or main effect for condition (P=0.206) and time (P=0.078), indicating that irrespective of the amplitude of the HIIE, FS results were similar between conditions. The effect size (ES) analysis showed a small effect in favour of HIIE-90/50 (ES=0.30) and HIIE-100/40 (ES=0.26) and a null effect on HIIE-110/30 (ES=0.08) when compared to VICE. Chi-squared analysis showed no significant differences between conditions in the number of participants that reduced, maintained, or increased the FS from pre-exercise to last stimulus and recovery indicating a high variability of the affective responses. HIIE sessions provide similar affective responses when performed at the same average intensity, even with different amplitudes.

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.

Different Endurance Exercise Modalities, Different Affective Response: A Within-Subject Study

Affect experienced during an exercise session is supposed to predict future exercise behavior. However, empirical evidence reveals high variability in affective response to different exercise modalities. Thus, the purpose of the present study was to compare acute affective response and its variation during three different endurance exercise modalities: (a) moderate-intensity continuous exercise (MICE), (b) vigorous-intensity continuous exercise (VICE), and (c) high-intensity interval exercise (HIIE). Using the dual-mode theory as a theoretical framework, cognitive and interoceptive factors were considered as potential predictors of in-task affective response. In a within-subject design, 40 insufficiently active healthy participants (aged from 20 to 40 years) attended three sessions per exercise modality on a cycle ergometer. Affective valence (measured by the Feeling Scale), two cognitive factors (perceived competence and awareness of interoceptive cues), and one interoceptive factor (heart rate) were assessed before, during, and after each exercise session. Mixed models with three levels (subject, exercise session, and time point) revealed more positive affective valence during MICE compared with VICE (p < 0.001) and HIIE (p < 0.01), while there was no significant difference between the latter two. Levene's test results showed the highest variability of in-task affective valence during VICE (ps < 0.01). Regarding the course across the session, MICE was associated with a constant slight increase in affective valence from pre- to post-exercise (p < 0.05), whereas VICE and HIIE caused a decline in pleasure, followed by an affective rebound immediately after exercise termination (ps < 0.01). The highest importance of cognitive and interoceptive factors for in-task affective valence was observed in VICE (ps < 0.05). The current findings provide support for the tenets of the dual-mode theory, however, indicating that there may be differences in the affect-intensity relationship between continuous and interval exercise. In conclusion, the study results concerning previously insufficiently active individuals extend the knowledge of how exercise can positively shape affective well-being depending on exercise modality and psychophysiological influences. This knowledge enables public health practitioners to design more individualized activity recommendations, thereby improving the subjective experience of exercise.

Using Focus Groups and Interviews to Inform the Design of a Workplace Exercise Programme: An Example From a High-Intensity Interval Training Intervention

OBJECTIVE

Using a formative evaluation of a high-intensity interval training (HIIT) intervention, we illustrate how qualitative data can inform the development of workplace exercise interventions.

METHOD

Eight focus groups and four interviews were conducted with employees (n = 38) and management (n = 4) from six office-based organisations before intervention implementation.

RESULTS

Some participants thought workplace-based HIIT would be practical, given the limited time required. Others perceived it may not be acceptable for all individuals, given the exercise intensity. With consideration of identified barriers (workload/family commitments effecting time availability) and facilitators (flexible working conditions) participants' perspectives were incorporated into the intervention protocol. A short-term group-based intervention was preferred, with a choice of exercise modes (based on stair climbing, stepping or boxing).

CONCLUSION

This study provides a framework to incorporate stakeholders' perspectives into the development of workplace exercise interventions.

Feasibility and Provisional Efficacy of Embedding High-Intensity Interval Training Into Physical Education Lessons: A Pilot Cluster-Randomized Controlled Trial

PURPOSE

The aim of this study was to determine the feasibility of generalist school teachers delivering curriculum connected high-intensity interval training in a school's physical education class time.

METHOD

Two schools volunteered to participate. A total of 84 students (11.9 [0.5] y, M = 64 and F = 19) volunteered to participate. Four classes from 2 schools were randomized to either intervention (n = 53) or control (n = 31) for one school term (8 wk). Intervention class teachers participated in a 1-day workshop instructing them how to deliver twice weekly, high-intensity interval training sessions. The control classes continued with their usual physical education curriculum. Recruitment, intervention fidelity, and program satisfaction were assessed. Preliminary efficacy (primary outcome cardiorespiratory fitness) was quantified using generalized linear mixed models, expressed as effect size. A range of secondary outcomes was also assessed.

RESULTS

The recruitment rate was 88%. About 84% of the sessions were delivered. The heart rate peak over all sessions was 89.6% (13%) of the predicted maximum. The intervention teachers reported high levels of satisfaction. Almost all student participants were positive about participating. No adverse events occurred. The adjusted between-group difference for cardiorespiratory fitness was trivial (effect size 0.02).

CONCLUSIONS

This teacher-delivered high-intensity interval training program was feasible and acceptable to both teachers and student participants. It is therefore potentially scalable.

Affective and Enjoyment Responses to Sprint Interval Exercise at Different Hypoxia Levels

Benefits of performing sprint interval training (SIT) under hypoxic conditions on improving cardiorespiratory fitness and body composition have been well-documented, yet data is still lacking regarding affective responses to SIT under hypoxia. This study aimed to compare affective responses to SIT exercise under different oxygen conditions. Nineteen active males participated in three sessions of acute SIT exercise (20 repetitions of 6 s of all-out cycling bouts interspersed with 15 s of passive recovery) under conditions of normobaric normoxia (SL: PIO₂ 150 mmHg, FIO₂ 0.209), moderate hypoxia (MH: PIO₂ 117 mmHg, FIO₂ 0.154, simulating an altitude corresponding to 2500 m), and severe hypoxia (SH: PIO₂ 87 mmHg, FIO₂ 0.112, simulating an altitude of 5000 m) in a randomized order. Perceived exertions (RPE), affect, activation, and enjoyment responses were recorded before and immediately after each SIT session. There were no significant differences across the three conditions in RPE or the measurements of affective responses, despite a statistically lower SpO₂ (%) in severe hypoxia. Participants maintained a positive affect valence and reported increased activation in all the three SIT conditions. Additionally, participants experienced a medium level of enjoyment after exercise as indicated by the exercise enjoyment scale (EES) and physical activity enjoyment scale (PACES). These results indicated that performing short duration SIT exercise under severe hypoxia could be perceived as pleasurable and enjoyable as performing it under normoxia in active male population.

A short-term exercise program in patients with multiple sclerosis: is body mass index important?

Obesity is a health problem that can exacerbate the symptoms of multiple sclerosis (MS). In the current study, we aimed to investigate the effectiveness of a short-term exercise program on fatigue, depression, anxiety, and walking performance in normal-weight and overweight patients with MS (PwMS). Sixty-two PwMS were divided into groups according to their BMI (BMI normal/BMI high). Also, they were all included in the exercise program. The participants took a moderate-intensity walking program 5 days a week for 4 weeks, including 30 min between 5 min of warm-up and 5 min of cooling periods. Also, patients underwent breathing, posture, flexibility, and stretching exercises for 4 weeks. Fatigue, depression, anxiety, 6-minute walking test (6MWT), and BMI were measured before and after the 4 weeks. After the exercise program, there were statistically significant improvements in fatigue, depression, anxiety, and the 6MWT. However, no relation could be detected between the examined variables and BMI. All patients participated effectively in the exercise program, regardless of BMI. The results obtained from this study support that a short-term exercise program is an effective therapeutic intervention, unrelated to BMI, in improving fatigue, depression, anxiety, and walking performance in PwMS.

High-Intensity Interval Training in Older Adults: a Scoping Review

High-intensity interval training (HIIT) is an increasingly popular form of aerobic exercise which includes bouts of high-intensity exercise interspersed with periods of rest. The health benefits, risks, and optimal design of HIIT are still unclear. Further, most research on HIIT has been done in young and middle-aged adults, and as such, the tolerability and effects in senior populations are less well-known. The purpose of this scoping review was to characterize HIIT research that has been done in older adults including protocols, feasibility, and safety and to identify gaps in the current knowledge. Five databases were searched with variations of the terms, "high-intensity interval training" and "older adults" for experimental or quasi-experimental studies published in or after 2009. Studies were included if they had a treatment group with a mean age of 65 years or older who did HIIT, exclusively. Of 4644 papers identified, 69 met the inclusion criteria. The average duration of training was 7.9 (7.0) weeks (mean [SD]) and protocols ranged widely. The average sample size was 47.0 (65.2) subjects (mean [SD]). Healthy populations were the most studied group (n = 30), followed by subjects with cardiovascular (n = 12) or cardiac disease (n = 9), metabolic dysfunction (n = 8), and others (n = 10). The most common primary outcomes included changes in cardiorespiratory fitness (such as VO2peak) as well as feasibility and safety of the protocols as measured by the number of participant dropouts, adverse events, and compliance rate. HIIT protocols were diverse but were generally well-tolerated and may confer many health advantages to older adults. Larger studies and more research in clinical populations most representative of older adults are needed to further evaluate the clinical effects of HIIT in these groups.

Acute effect of HIIT on testosterone and cortisol levels in healthy individuals: A systematic review and meta-analysis

To determine the acute effect of a single high-intensity interval training (HIIT) session on testosterone and cortisol levels in healthy individuals, a systematic search of studies was conducted in MEDLINE and Web of Science databases from inception to February 2020. Meta-analyses were performed to establish the acute effect of HIIT on testosterone and cortisol levels immediately after a single HIIT session; after 30 min and 60 min (primary outcomes); and after 120 min, 180 min, and 24 h (secondary outcomes, only for pre-post intervention groups). Potential effect-size modifiers were assessed by meta-regression analyses and analyses of variance. Study quality was assessed using the Cochrane's risk of bias tool and the Physiotherapy Evidence Database scale. The meta-analyses of 10 controlled studies (213 participants) and 50 pre-post intervention groups (677 participants) revealed a significant increase in testosterone immediately after a single HIIT session (d = 0.92 and 0.52, respectively), which disappeared after 30 min (d = 0.18 and -0.04), and returned to baseline values after 60 min (d = -0.37 and -0.16). Significant increases of cortisol were found immediately after (d = 2.17 and 0.64), after 30 min (d = 1.62 and 0.67) and 60 min (d = 1.32 and 0.27). Testosterone and cortisol levels decreased significantly after 120 min (d = -0.48 and -0.95, respectively) and 180 min (d = -0.29 and -1.08), and returned to baseline values after 24 h (d = 0.14 and -0.02). HIIT components and participant's characteristics seem to moderate the effect sizes. In conclusion, testosterone and cortisol increase immediately after a single HIIT session, then drop below baseline levels, and finally return to baseline values after 24 h. This meta-analysis provides a better understanding of the acute endocrine response to a single HIIT session, which would certainly be valuable for both clinicians and coaches in the prescription of exercise programs to improve health and performance. Testosterone and cortisol may be used as sensitive biomarkers to monitor the anabolic and catabolic response to HIIT.

Effects of a 12-week HIIT + group mediated cognitive behavioural intervention on quality of life among inactive adults with coeliac disease: findings from the pilot MOVE-C study

OBJECTIVE

The purpose of the pilot MOVE-C study was to examine the effects of a 12-week high-intensity interval training (HIIT) plus lifestyle education program on quality of life (QoL), behavioural and psychosocial outcomes among inactive adults with coeliac disease.

DESIGN

This study used a 3 (time: baseline, immediately post and three months post) × 2 (group: experimental versus waitlist control) mixed design. After completing baseline testing, 41 participants were randomised to one of two groups: HIIT + or waitlist control (WLC). The HIIT + intervention involved twice-weekly HIIT, during which participants progressed to 14 × 30 s intervals (90% heart rate max; HRmax), with 2-minute recovery (50% HRmax). The HIIT + intervention also included six bi-weekly education sessions.

RESULTS

Participants in HIIT + reported significant improvements in QoL and exercise behaviour immediately post-intervention, and this was sustained three months post-intervention, whereas no changes in QoL nor exercise behaviour were reported in WLC. Improvements were also reported among HIIT + immediately after the intervention for gastrointestinal symptoms and self-compassion. All participants reported significant improvements in adherence to a GFD immediately post-intervention.

CONCLUSION

Findings from this pilot study provide preliminary evidence that a tailored exercise and lifestyle intervention can lead to improved QoL, exercise behaviour, gastrointestinal symptoms and self-compassion among inactive adults with coeliac disease.

Affective Responses during High-Intensity Interval Exercise Compared with Moderate-Intensity Continuous Exercise in Inactive Women

This study aimed to investigate the effects of an acute bout of high-intensity interval exercise (HIIE) and moderate-intensity continuous exercise (MICE) on affective responses in inactive women. Thirty women with normal body mass index (BMI) and 30 women with BMI ≥ 24 kg/m² participated in the study. All participants completed a graded exercise test and performed two exercise sessions (HIIE and MICE) in random order. Affective responses were assessed during and after each exercise session, using the rating of perceived exertion (RPE), Self-Assessment-Manikin (SAM), and Subjective Exercise Experience Scale (SEES). The results showed that the RPE scores were significantly higher in HIIE than in MICE. HIIE resulted in significantly lower pleasure scores using the SAM while arousal and dominance scores were significantly higher with HIIE compared to MICE. Positive well-being scores using the SEES were significantly lower with HIIE and both psychological distress and fatigue scores were significantly higher with HIIE. The results showed that affective responses with MICE were more positive than with HIIE, but no differences were found between normal and overweight/obese women. Based on these results, MICE may be a more acceptable exercise program for inactive women regardless of their weight status.

Effects of High-Intensity Interval Training Protocols on Liver Enzymes and Wellness in Women

Background

Single-modality, high-intensity interval training (HIIT) using traditional cardiorespiratory exercise selection has been found to provide similar and sometimes superior cardiometabolic effects compared with moderate-intensity continuous training. However, little is known regarding the cardiometabolic and psychosocial effects of HIIT using resistance training modalities. Therefore, this study aims to compare the effects of HIIT using rowing (R-HIIT) and multimodal HIIT (MM-HIIT) using resistance training on liver enzymes, cardiometabolic risk factors, and psychosocial outcomes.

Method

Recreationally active females with a body mass index <30 kg/m² (N = 16, 23.0 ± 5.9 years) were randomized into a MM-HIIT or R-HIIT group and completed a 12-week HIIT intervention (ClinicalTrials.gov registration number: https://clinicaltrials.gov/ct2/show/NCT03093441) using principles of social cognitive theory (SCT). Participants completed pre- and postintervention measurements on anthropometrics, resting heart rate, blood pressure, blood measures (lipids, liver enzymes, and glucose), exercise self-efficacy, and perceived wellness. Analysis of covariance was used to examine differences in postintervention measures between groups after controlling for baseline values, waist circumference, and waist-to-height ratio.

Results

R-HIIT group had significantly decreased alanine aminotransferase (mean difference = 13.16, P=0.013, effect size (ES) = 0.44, confidence interval (CI) = 3.40 to 22.92) and aspartate aminotransferase (mean difference = 10.79, P=0.024, ES = 0.38, CI = 1.67 to 19.90) levels compared with the M-HIIT group, and the whole group had improved wellness scores (14.72 ± 2.6 to 16.89 ± 2.76, P=0.002).

Conclusion

R-HIIT may be an effective preventative method for improving liver health in females without obesity. When using principles of SCT, HIIT may enhance overall well-being.

The effects of three types of exercise training on steroid hormones in physically inactive middle-aged adults: a randomized controlled trial

PURPOSE

Physical inactivity and ageing are associated with imbalances in anabolic/catabolic steroid hormones, jeopardizing health. We investigated the effects of three types of training on plasma steroid hormone levels in physically inactive, middle-aged adults.

METHODS

A 12-week randomized controlled trial was performed with a parallel-group design. A total of 67 (36 women) middle-aged adults (45-65 years old) were randomly assigned to (1) no exercise (control), (2) concurrent training based on the international physical activity recommendations (PAR), (3) high-intensity interval training (HIIT), or (4) HIIT plus whole-body electromyostimulation (HIIT + EMS). The training volume in the PAR group was 150 min/week at 60-65% of the heart rate reserve for aerobic training and ~ 60 min/week at 40-50% of the one-repetition maximum for resistance training. The training volume in the HIIT and HIIT + EMS groups was 40-65 min/week at > 95% of the maximum oxygen uptake in long interval sessions, and > 120% of the maximum oxygen uptake in short interval sessions.

RESULTS

Compared to the control group, dehydroepiandrosterone sulfate increased in the PAR, HIIT, and HIIT + EMS groups (~ 14%, ~ 14%, and ~ 20%, respectively; all P < 0.01). Cortisol decreased in the PAR, HIIT, and HIIT + EMS groups (~ - 17%, ~ - 10%, and ~ - 23%, respectively; all P ≤ 0.05). Testosterone increased in the HIIT and HIIT + EMS groups (~ 28%, and ~ 16%, respectively; all P ≤ 0.01). Free testosterone increased in the HIIT and HIIT + EMS groups (~ 30% and ~ 18% respectively; all P ≤ 0.01). No significant increase in sex hormone-binding globulin was observed (P = 0.869).

CONCLUSION

Our findings suggest that HIIT, with or without whole-body EMS, can significantly enhance steroid hormones status in previously physically inactive middle-aged adults. The PAR program led to slight improvements than the HIIT and HIIT + EMS groups despite the application of a higher training volume.

CLINICAL TRIAL REGISTRY

NCT03334357 (ClinicalTrials.gov). November 7, 2017 retrospectively registered.

Might High-Intensity Interval Exercise Be Remembered as More Pleasurable? An Attempt to Test the Peak-End Rule in the Exercise Context

Given humans' limited ability to recall past experiences for evaluation, scholars have proposed the peak-end rule stating that if perceived discomfort at the end of an aversive experience is lower than the peak discomfort experienced, the aversive experience will be remembered more positively. The purpose of this study was to evaluate the peak-end rule as applied to high-intensity interval exercise (HIIE). Participants were 30 inactive men (M age = 27.9, SD =  5.2 years). In the first session they performed a graded exercise test on cycle-ergometer to determine their maximal aerobic power (MAP) (M = 233, SD = 35W); and, in the second and third sessions, they performed two HIIE protocols in randomized order: (a) Short trial - 20-minutes of HIIE, composed of 30-second efforts at 100% of MAP interspersed by 30-seconds of passive recovery; and (b) Long trial - 20-minutes of the short trial, plus 10-minutes more of HIIE, decreasing 3% of MAP in each additional bout, resulting in 70% of MAP in the last bout. During exercise, we recorded the participants' rating of perceived exertion (RPE) and affect, using the Feeling Scale (FS). At 30-minutes post-exercise, we again recorded the participants' affect, using the Global Affect Evaluation (GAE) and their session-RPE, and we recorded their enjoyment, using the Physical Activity Enjoyment Scale (PACES). In the last session, the participants chose a favorite protocol to repeat. All sessions were interspersed by at least 72 hours. The 10-minutes extra HIIE in the Long-trial condition resulted decreased heart rate values (M = 157, SD = 13bpm to M = 144, SD = 14bpm; p < 0.001), but psychological responses during and after exercise did not differ, nor did participants' preferred HIIE protocol. As the load drop for the Long-trial was not enough to change the psychological responses during exercise, there was no difference in the retrospective evaluation as the peak-end rule would have suggested.

Exercise for affect and enjoyment in overweight or obese males: a comparison of high-intensity interval training and moderate-intensity continuous training

High-intensity interval training (HIIT) is effective for generating positive cardiovascular health and fitness benefits. This study compared HIIT and moderate-intensity continuous training (MICT) for affective state and enjoyment in sedentary males with overweight or obesity.Twenty-eight participants performed stationary cycling for 6 weeks × 3 sessions/week. Participants were randomly allocated to HIIT (N=16) (10 × 1-minute intervals at ~90% peak heart rate) or MICT (N=12) (30 minutes at 65-75% peak heart rate). Affective state changes were assessed after 6-weeks training. Enjoyment and acute change in affect were assessed after individual training sessions.HIIT participants reported improved positive affect following 6 weeks training (∆ 3.6 ± 4.6, p = 0.007, effect size d = 0.70), without corresponding improvement in negative affect (p = 0.48, d = -0.19). MICT did not induce any improvement in positive affect (p = 0.56, d = 0.16) or negative affect (p = 0.23, d = -0.41). Enjoyment ratings were comparable for both exercise formats (HIIT: 4.4 ± 0.4 on a 7-point scale; MICT: 4.3 ± 0.3; p = 0.70, d = 0.15).Six weeks of HIIT induced improvement in positive affect in sedentary participants with overweight or obesity. Enjoyment of training was only slightly above neutral levels for both training formats.What's already known about this topic? Exercise training can improve general affect however the optimal exercise characteristics for improving affect are unclear.Studies assessing the relative enjoyment of HIIT in comparison to MICT have largely been equivocal to date.What does this study add? HIIT can improve affective state in males with overweight or obesity.Six weeks of stationary cycling HIIT were rated as only mildly enjoyable, comparable to ratings for MICT.

Review of High-Intensity Interval Training for Cognitive and Mental Health in Youth

PURPOSE

High-intensity interval training (HIIT) has emerged as a time-efficient strategy to improve children's and adolescents' health-related fitness in comparison to traditional training methods. However, little is known regarding the effects on cognitive function and mental health. Therefore, the aim of this systematic review was to evaluate the effect of HIIT on cognitive function (basic information processing, executive function) and mental health (well-being, ill-being) outcomes for children and adolescents.

METHODS

A systematic search was conducted, and studies were eligible if they 1) included a HIIT protocol, 2) examined cognitive function or mental health outcomes, and 3) examined children or adolescents (5-18 yr). Separate meta-analyses were conducted for acute and chronic studies, with potential moderators (i.e., study duration, risk of bias, participant age, cognitive demand, and study population) also explored.

RESULTS

A total of 22 studies were included in the review. In acute studies, small to moderate effects were found for executive function (standardized mean difference [SMD], 0.50, 95% confidence interval [CI], 0.03-0.98; P = 0.038) and affect (SMD, 0.33; 95% CI, 0.05-0.62; P = 0.020), respectively. For chronic studies, small significant effects were found for executive function (SMD, 0.31; 95% CI, 0.15-0.76, P < 0.001), well-being (SMD, 0.22; 95% CI, 0.02-0.41; P = 0.029), and ill-being (SMD, -0.35; 95% CI, -0.68 to -0.03; P = 0.035).

CONCLUSIONS

Our review provides preliminary review evidence suggesting that participation in HIIT can improve cognitive function and mental health in children and adolescents. Because of the small number of studies and large heterogeneity, more high-quality research is needed to confirm these findings.