Psychological and Behavioral Responses to Interval and Continuous Exercise

Customizing intense interval exercise training prescription using the "frequency, intensity, time, and type of exercise" (FITT) principle

Intense interval exercise training induces various physiological and metabolic adaptations related to performance and health. For designing a program, the F.I.T.T. principle, referring to frequency, intensity, time, and type of exercise, can be used to manipulate the level of physiological stress in the body, leading to various adaptations. Modifying these four parameters results in a wide range of interval protocols that are safe and effective for different populations including athletes and individuals with chronic diseases. In this review, we present how the manipulation of the F.I.T.T. components can alter the acute and chronic cardiorespiratory, metabolic, perceptual, and affective responses and adaptations to intense interval exercise training. From this evidence, it appears that the duration of the exercise bout and recovery interval are critical parameters for the manipulation of almost all acute responses, enabling periodization of intense interval exercise training, and promoting optimal adaptations and exercise adherence. In addition, a considerable level of adaptations may be achieved with training frequencies as low as once or twice per week and with lower than maximal intensities, adding to the feasibility of this exercise mode. Overall, by varying these parameters, the design of an intense interval exercise training program can be tailored according to the needs and abilities of each individual, and an optimized training prescription may be achieved.

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.

The Effectiveness of High-Intensity Interval Training vs. Cardio Training for Weight Loss in Patients with Obesity: A Systematic Review

Background: Obesity is a growing public health issue, increasing the risk of metabolic disorders and cardiovascular diseases. Physical activity is a key factor in obesity treatment; however, the effectiveness of different exercise modalities remains unclear, especially considering age-related physiological differences. High-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) are two commonly recommended strategies, but their impact on fat reduction across different age groups has not been thoroughly analyzed. This study aims to determine which training modality is most effective for fat reduction in individuals with obesity, considering age as a crucial factor in exercise response. Methods: A systematic review was conducted, analyzing studies published between 2014 and 2024. The inclusion criteria focused on the studies comparing HIIT and MICT effects on body composition in obese individuals of different age groups. The data extraction included training protocols, fat mass reduction, and adherence levels. The primary outcomes measured changes in body fat percentage and muscle mass retention. Results: HIIT was found to be most effective for younger individuals (18-30 years), promoting fat oxidation and muscle retention. In middle-aged adults (31-40 years), both HIIT and MICT yielded similar benefits, with MICT preferred due to better adherence. In older adults (41-60 years), MICT provided a more sustainable strategy for fat reduction and muscle preservation. However, the variability across the studies limits definitive conclusions. Conclusions: Age influences the effectiveness of HIIT and MICT for obesity treatment, highlighting the need for age-specific exercise recommendations. Future studies should standardize training protocols and assess long-term metabolic adaptations to optimize physical activity guidelines.

Relationship between psychological empowerment, physical activity enjoyment, and response to a HIIT Program in physically inactive young women: a prospective multicentre study

BACKGROUND

This study aimed to investigate the relationship of psychological empowerment and enjoyment of physical activity with changes in physical activity levels, sleep quality, and muscular endurance following a high-intensity interval training (HIIT) program in physically inactive young women.

METHODS

A total of 61 physically inactive young women (age: 20.1 ± 2.7 y) were recruited to participate in a six-month HIIT intervention delivered via a smartphone app. Outcome measures included physical activity levels (MET-min/week), muscular endurance (plank test), and sleep quality through the Pittsburgh Sleep Quality Index (PSQI). The Healthy Lifestyle and Personal Control Questionnaire (HLPCQ) and the Physical Activity Enjoyment Scale (PACES) were used to assess psychological empowerment and enjoyment, respectively. Repeated measures ANOVA and covariate analyses were performed to evaluate the impact of the intervention and the role of psychological empowerment and enjoyment.

RESULTS

At 6 months, significant improvements in physical activity (p < 0.001; ηp²=0.336) and muscular endurance (p = 0.005; ηp²=0.085) were observed, with large and moderate effect sizes, respectively. The PACES showed a significant interaction with time for MET-min/week (F = 11.67, p = 0.001, ηp²=0.129), suggesting that enjoyment influenced the increase in physical activity. No significant differences in sleep quality were observed (p > 0.05).

CONCLUSION

Enjoyment plays a crucial role in the response to HIIT programs among physically inactive young women, particularly in improving weekly physical activity levels. Psychological training showed no significant relationship with the outcomes studied.

Acute effects of different physical activity on executive function and regulation role of beta oscillation in sedentary youth frontal region

Chronic sedentary behavior can have a negative impact on the executive function (EF) of young people. While physical activity (PA) has been shown to improve this phenomenon, the effects of different types of PA on EF vary. In this study, we compared the effects of moderate-intensity continuous training (MICT) (60-70% HRmax, 30 min), body weight training (BWT) (2 sets tabata, 20 min), and mind-body exercise (MBE) (2 sets Yang style shadowboxing, 20 min) on EF in 59 sedentary youth (n = 59, age = 20.36 ± 1.78, BMI = 24.91 ± 1.82, P>0.05) to identify the optimal dose of PA for improving EF. Metrics related to the EF task paradigm included stop signal, electroencephalogram (EEG), event-related potential (ERP), P300, N200, error-related negativity (ERN), and error positivity (Pe). error positivity (Pe), and β-wave in frontal lobe; training monitoring, including heart rate (HR), rating of perceived exertion (RPE), feeling scale (FS), and dual-mode model (DMM); load assessment, including Edward's TRIMP (TRIMP) and session-RPE (s-RPE). The study results indicate that BWT significantly improved accuracy in terms of EF (F = 16.84, P = 0.0381) and was comparable to MICT in terms of shortening reaction time (F = 58.03, P = 0.0217; F = 75.49, P = 0.0178). Regarding ERP, BWT reduced the amplitude values of N200 compared to ERN (F = 44.35, P = 0.0351; F = 48.68, P = 0.0317), increased P300 compared to Pe (F = 97.72, P<0.01; F = 29.56, P = 0.0189), and shortened P300 latency (F = 1.84, P = 0.0406). In contrast, MICT was only effective for P300 with Pe (F = 66.59, P = 0.0194; F = 21.04, P = 0.0342) and shortened N200 latency (F = 27.29, P = 0.0411). The increase in total amplitude and β-oscillation in terms of EEG was proportional to the exercise intensity, with the difference between MICT and BWT being present at 5-20 Hz, and MBE at 10-15 Hz. Regarding training load, the order of HR, RPE, TRIMP, and s-RPE was BWT > MICT > MBE (F = 202.69; F = 114.69; F = 114.69; P = 0.0342). The latency of N200 was also shortened (F = 27.29, P = 0.0411). The results showed that PA improves EF in sedentary youth, although BWT works best, it leads to a decrease in motor perception. Initially, MICT was scheduled alongside MBE and later replaced with BWT. This may help establish an exercise habit while improving EF.

Physiological and perceptual responses to sprint interval exercise using arm versus leg cycling ergometry

Increases in power output and maximal oxygen consumption (V ˙ O 2 max) occur in response to sprint interval exercise (SIE), but common use of "all-out" intensities presents a barrier for many adults. Furthermore, lower-body SIE is not feasible for all adults. We compared physiological and perceptual responses to supramaximal, but "non-all-out" SIE between leg and arm cycling exercise. Twenty-four active adults (mean ​± ​SD age: [25 ​± ​7] y; cyclingV ˙ O 2 max: [39 ​± ​7] mL·kg-1·min-1) performed incremental exercise using leg (LCE) and arm cycle ergometry (ACE) to determineV ˙ O 2 max and maximal work capacity (Wmax). Subsequently, they performed four 20 ​s bouts of SIE at 130% Wmax on the LCE or ACE at cadence ​= ​120-130 ​rev/min, with 2 ​min recovery between intervals. Gas exchange data, heart rate (HR), blood lactate concentration (BLa), rating of perceived exertion (RPE), and affective valence were acquired. Data showed significantly lower (p ​< ​0.001) absolute mean ([1.24 ​± ​0.31] L·min-1 vs. [1.59 ​± ​0.34] L·min-1; d ​= ​1.08) and peakV ˙ O 2 ([1.79 ​± ​0.48] L·min-1 vs. [2.10 ​± ​0.44] L·min-1; d ​= ​0.70) with ACE versus LCE. However, ACE elicited significantly higher (p ​< ​0.001) relative mean ([62% ​± ​9%]V ˙ O 2 max vs. [57% ​± ​7%]V ˙ O 2 max, d ​= ​0.63) and peakV ˙ O 2 ([88% ​± ​10%]V ˙ O 2 max vs. [75% ​± ​10%]V ˙ O 2 max, d ​= ​1.33). Post-exercise BLa was significantly higher ([7.0 ​± ​1.7] mM vs. [5.7 ​± ​1.5] mM, p ​= ​0.024, d ​= ​0.83) for LCE versus ACE. There was no significant effect of modality on RPE or affective valence (p ​> ​0.42), and lowest affective valence recorded (2.0 ​± ​1.8) was considered "good to fairly good". Data show that non "all-out" ACE elicits lower absolute but higher relative HR andV ˙ O 2 compared to LCE. Less aversive perceptual responses could make this non-all-out modality feasible for inactive adults.

"But will they do it?" Challenging assumptions and incivility in the academic discourse on high-intensity interval training

Debate over whether to promote high-intensity interval training (HIIT) in public-health contexts has centred on assumptions that people will have negative psychological responses to HIIT, leading to poor adoption and adherence. We challenge these assumptions through reviews of (1) studies that have measured psychological responses to HIIT and (2) studies that have measured adherence to HIIT protocols in supervised or unsupervised settings. Overall, the evidence suggests that HIIT is just as enjoyable as moderate-intensity continuous training (MICT). In supervised situations, on average, adherence is similarly high for HIIT and MICT (>89%). In unsupervised situations, adherence is similarly lower for both HIIT and MICT (<69%). Based on these findings, we recommend that attention be directed toward improving behaviour-change and maintenance for all types of exercise. Resources are better spent addressing fundamental questions about exercise initiation and adherence, than perpetuating a vitriolic and uncivil debate over the value of HIIT versus MICT. We discuss how debate, incivility, and bullying undermine scientific progress and we issue a call for respectful, civil dialogue in academic HIIT discussions. We conclude with recommendations that can be used by all members of the scientific community to practice, champion, and defend civil discourse.

Optimal dose of vigorous physical activity on cardiorespiratory and perceptual response for sedentary youths using internal load monitoring

Introduction

Vigorous physical activity (VPA) has been demonstrated to enhance cardiorespiratory fitness (CRF) in sedentary college students more effectively than other PA. However, differences in training volume may affect this outcome. This study examines the physiological, psychological, and internal training load (ITL) characteristics of VPA with varying volumes in a single session.

Methods

Thirty sedentary college students were divided into three groups: high-intensity interval training (HIIT), sprint interval training (SIT), and threshold training (THR). PA process was monitored. The study measured various cardiorespiratory parameters, including heart rate (HR), respiratory waveform and amplitude, respiratory rate (RR), tidal volume (TV), minute ventilation volume (VE), fractional concentration of oxygen in end-tidal gas (O2%), fractional concentration of end-tidal carbon dioxide (CO2%), global oxygen consumption (VO2), carbon dioxide discharge (VCO2), and the amount of carbon dioxide in the air. The following physiological indicators were measured: carbon dioxide discharge (VCO2), Oxygen pulse (OP), and respiratory exchange ratio (RER). Additionally, subjective perception indicators were recorded, including the feeling scale (FS), rating of perceived exertion (RPE), and dual-mode model (DMM). The session-RPE (s-RPE) and Edward's TRIMP were used to measure ITL.

Results

There were no significant differences in HR across the three conditions. THR had the highest level of TV (p = 0.043), but RR was significantly lower than that of HIIT and SIT (p < 0.01). HIIT had the highest levels of VO2, VCO2, O2%, and OP (p < 0.05). RPE was higher in HIIT and SIT compared to THR (p < 0.01), but the difference in FS was not significant. The DMM time-domain trajectories were similar in HIIT and THR. The correlation between exercise intensity, RPE, and FS was highest in THR group (r = 0.453, r = -0.58, r = -0.885). ITL did not show a significant difference between three conditions, but TRIMP and s-RPE readings were opposite in magnitude.

Conclusion

This study proposes that using an appropriate amount of THR to foster interest and adaptive strength during the PA habit establishment period, incorporating HIIT to enhance exercise efficiency during the adaptation period, and implementing SIT to reduce the monotony may effectively enhance the cardiorespiratory fitness of sedentary college students and establish PA habit.

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

ABSTRACT

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

Effect of High-Intensity Interval, Moderate-Intensity Continuous, and Self-Selected Intensity Training on Health and Affective Responses

Purpose: To compare the effects of 12-week high-intensity interval (HIIT), moderate-intensity continuous (MICT), and self-selected intensity training (SSIT) on health outcomes and affective responses. Methods: Seventy-three overweight/obese inactive adults (62% woman; age, 31.4 ± 7.2 years; height, 1.66 ± 0.09 cm; Body mass index, 28.9 ± 2.7 kg.m-2) who were randomized into HIIT (n = 23), MICT (n = 24) and SSIT (n = 26) groups. The training was conducted three times per week in an outdoor environment, with 4 weeks under direct supervision and 8 weeks with semi-supervision. Cardiorespiratory fitness, body composition, and metabolic profile were evaluated at baseline and at the end of the 4th and 12th weeks. Core affect was measured during all training sessions. Results: Peak oxygen uptake improved in all groups after 4 and 12 weeks compared with baseline. Only the SSIT had reductions in body fat throughout the intervention. No improvements were observed in the metabolic profile across all groups. SSIT was perceived as more pleasurable than HIIT; however, there were no differences in affective responses between SSIT and MICT. Affective responses in-task (e.g. negative and positive peak, rate of change and affect at the end of the exercise session) predicted the HIIT and SSIT exercises attendance rate. Conclusion: Regardless of the exercise training protocol, overweight/obese inactive adults improved health outcomes, which suggests the prescribing HIIT, MICT, and SSIT in outdoor environments. SSIT should be considered in order to optimize the pleasure during training sessions. Affective response more positive in-task of the HIIT and SSIT is associated with greater attendance rate in these exercise protocols.

Clinical value and mechanistic analysis of HIIT on modulating risk and symptoms of depression: A systematic review

Background

The exact causal mechanisms of depression remain unclear due to the complexity of the triggers, which has led to limitations in treating depression using modern drugs. High-intensity interval training (HIIT) is as effective as medication in treating depression without toxic side effects. Typically, HIIT requires less time commitment (i.e., shorter exercise duration) and exhibits pronounced benefits on depressive symptoms than other forms of physical exercise. This review summarizes the risk reduction and clinical effects of HIIT for depression and discusses the underlying mechanisms, providing a theoretical basis for utilizing HIIT in treating depression.

Methods

A database search was conducted in PubMed, Embase, Web of Science, and Scopus from inception up to October 2022. The methodological quality of the included literature was evaluated by the physiotherapy evidence database (PEDro) scale criteria. The review focused on evaluating the changes in depression risk or symptoms of HIIT interventions in healthy individuals, patients with depression, and patients with other disorders co-morbid with depression. Consequently, the mechanisms associated with depression related HIIT were summarized.

Results

A total of 586 participants (52 % female; mean age: 43.58±8.93 years) from 22 studies were included. Implementing HIIT using different exercise types alleviates depressive symptoms in individuals with depression and in individuals with depression who have exhibited comorbidities and reduced depression scale scores in subjects immediately after acute exercise. In addition, the long-interval HIIT and short-interval HIIT in the treatment of patients with cardiovascular or psychiatric disorders may reduce depressive symptoms via complex exercise-related changes on several levels, including by effecting the following measures: releasing monoamines, reducing neuronal death, inducing neurogenesis, modulating the functional homeostasis of the HPA axis, and enhancing the level of inflammation in the body.

Conclusion

HIIT is a relatively safe and effective antidepressant, which may involve multiple neurobiological mechanisms (release of monoamines, reducing neuronal death, inducing neurogenesis, modulating the functional homeostasis of the HPA axis, and enhancing the level of inflammation in the body), thereby reducing the risk or symptoms of depression in participants.

Exercise and Acute Affect

The study of the affective impact of physical activity and exercise has a long and fraught history. In this chapter we outline some of the longstanding issues, in the hopes that research moving forward will be more mindful of these. Included are: (a) what we are actually trying to assess; (b) measurement issues; (c) the timing of affective measurement; (d) research that highlights what we know and don't know; and (e) suggestions for moving forward.

The effects of equine-assisted activities on execution function in children aged 7-8 years: A randomized controlled trial

BACKGROUND

This study examines the effects of equine-assisted activity (EAA) training on executive functioning (EF) (inhibitory control, working memory, and cognitive flexibility) in children aged 7-8 years.

METHODS

Twenty-Four healthy children aged 7-8 years with a 1:1 ratio of boys to girls were randomly divided into EAA group (EAAG) or control group (CG). The subjects in EAAG were trained for 12 weeks, and CG participated in normal daily activities. All subjects conducted the Flanker, 1-Back, and More-odd shifting tasks at rest and recorded the average reaction times (RTs) and accuracy data of each task.

RESULTS

After 12 weeks of EAA intervention, EAAG showed a highly significant increase (p < .01) in mean RTs and accuracy in the Flanker and More-odd shifting tasks and a highly significant increase (p < .01) in accuracy only in 1-Back.

CONCLUSION

These findings suggest that 12-week EAA training can be effective in improving EF and promoting cognitive performance in children aged 7-8 years.

Acute physiological, perceived exertion and enjoyment responses during a 4-week basketball training: a small-sided game vs. high-intensity interval training

Introduction

Although previous research found that small-sided game (SSG) training was more enjoyable than high-intensity interval training (HIT) in various sports, no data were provided during longer training period in basketball. Furthermore, the comparison of internal loads between the two training approaches needs to be further examined. Thus, this study aimed to examine the acute physiological, perceived exertion and enjoyment responses during 4-week progressive basketball SSG or HIT programs.

Methods

Nineteen female collegiate basketball players were randomly assigned to two groups that performed either HIT (n = 10) or SSG (n = 9) 3 times per week for 4 continuous weeks. Average and percentage of maximal heart rate (HR_mean and %HR_max), rating of perceived exertion (RPE), and physical activity enjoyment (PACES) were determined during each training session.

Results

There was a main group effect in PACES (p < 0.001; ηp2 = 0.44, moderate), and SSG had higher PACES than HIT in each week (p < 0.05). There were no significant interactions or main group effects in HR_mean, %HR_max or RPE, but a main time effect was found in HR_mean (p = 0.004; ηp2 = 0.16, minimum), %HR_max (p < 0.001; ηp2 = 0.25, minimum), and RPE (p < 0.001; ηp2 = 0.31, moderate), respectively. In the SSG group, although no significant differences were found in HR responses, %HR_max was below 90% in week 1 and week 2. Accompanied with changes in %HR_max, RPE in week 1 and week 2 was lower than that in week 3 and week 4 (p < 0.05).

Conclusion

Our findings suggest that SSG and HIT elicit similar acute HR response and RPE level, but SSG is perceived as more enjoyable and therefore it is more likely to increase exercise motivation and adherence comparing to HIT. Moreover, it seems that half-court, 2 vs. 2 SS Gtraining format with modified rules and lasting ≥ 7.5 min should be prescribed as an enjoyable training alternative to provide optimal cardiovascular stimuli (> 90% of HR_max) for female basketball players.

Acute Cardiopulmonary Response of High-Intensity Interval Training with Elastic Resistance vs. High-Intensity Interval Training on a Treadmill in Healthy Adults

This study aims to describe and compare cardiopulmonary and subjective responses during high-intensity interval training with elastic resistance (EL-HIIT) and traditional high-intensity interval training (HIIT) sessions. Twenty-two healthy adults (27.6 ± 4.4 years) performed an EL-HIIT and a HIIT protocol consisting of 10 × 1 min at ~85% V·O2max prescribed by cardiopulmonary-specific tests. Pulmonary parameters, heart rate (HR), blood lactate, and rate of perceived exertion (RPE) were measured during exercise. Paired t-test and Cohen's d effect size were used to compare peak and average values. Two-way repeated measures ANOVA and mixed model with Bonferroni's post hoc test were used to compare each bout during the session. The EL-HIIT session showed higher peak and average values of HR, ventilation (V·E), relative and absolute oxygen uptake (V·O2), carbon dioxide production (V·CO2), and RPE than HIIT (p < 0.05). The effect size (ES) comparing HIIT and EL-HIIT was large for HR, V·E, and lactate (≥0.8) in peak values. Comparing each bout between HIIT and EL-HIIT, no difference was found in peak values (p > 0.05) during the session (excluding baseline, warm-up, and recovery). EL-HIIT presented a more pronounced cardiopulmonary and subjective response than HIIT.

"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.

Acute physiological responses to high-intensity interval exercise in patients with coronary artery disease

PURPOSE

Time spent closer to maximal effort during exercise is a potent stimulus for cardiorespiratory adaptations. The primary purpose was to determine which high-intensity interval exercise (HIIE) protocol provided the greatest physiological stimulus by comparing time spent ≥ 90% peak oxygen consumption (V̇O₂peak) and heart rate reserve (HRR) in patients with coronary artery disease (CAD) in response to 3 HIIE protocols and the exercise standard of care, moderate-intensity continuous exercise (MICE). A secondary purpose was to assess protocol preference.

METHODS

Fifteen patients with CAD (6 females, 67 ± 6 years) underwent measurements of V̇O₂ and heart rate during MICE and three HIIE protocols all performed on a treadmill. The HIIE protocols included one with long intervals (4 × 4-min), short intervals (10 × 1-min), and an adapted version of the 4 × 4 [Toronto Rehabilitation Institute Protocol, (TRIP)]. Time spent ≥ 90% V̇O₂peak and HRR were compared.

RESULTS

Time spent ≥ 90% V̇O₂peak was higher during 4 × 4 (6.3 ± 8.4 min) vs. MICE (1.7 ± 3.9 min; P = 0.001), while time spent ≥ 90% HRR was higher during 4 × 4 (6.0 ± 5.3 min) vs. MICE (0.1 ± 0.2 min; P < 0.001) and 10 × 1 (0.7 ± 0.8 min; P = 0.016). TRIP had similar responses as 10 × 1 and MICE. The 10 × 1 was the most preferred protocol and the 4 × 4 was the least preferred protocol.

CONCLUSION

Longer intervals (4 × 4) provided the greatest physiological stimulus compared to the exercise standard of care and shorter intervals. However, this protocol was least preferred which may impact exercise adherence. Although the physiological stimulus is important to maximize training adaptations, exercise preferences and attitudes should be considered.

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

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

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

Background

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

Methods

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

Results

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

Discussion

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

Attenuated Metabolic and Cardiorespiratory Responses to Isoenergetic High-Intensity Interval Exercise of Short Versus Long Bouts

PURPOSE

To compare the metabolic, cardiorespiratory and perceptual responses to three isoenergetic high-intensity interval exercise (HIIE) protocols of different bout duration and an isoenergetic continuous exercise protocol.

METHODS

Eleven healthy males (age, 28 ± 6 yr) performed four 20-min cycling trials of equal mean power output 1 wk apart. Participants cycled either continuously (CON) or intermittently with 10 s (HIIE10), 30 s (HIIE30), or 60 s (HIIE60) bouts at intensities corresponding to 49% (CON) or 100% of power at peak oxygen uptake (V̇O2peak). Recovery intervals during the HIIE trials were 15, 45, and 90 s, respectively.

RESULTS

Average V̇O2 was similar in the HIIE trials (2.29 ± 0.42, 2.20 ± 0.43, and 2.12 ± 0.45 L·min-1, for HIIE10, HIIE30, and HIIE60, respectively), whereas in CON (2.02 ± 0.38 L·min-1), it was lower than HIIE10 (P = 0.002) and HIIE30 (P = 0.043). Average pulmonary ventilation (VE) was higher in HIIE60 compared with HIIE10, HIIE30, and CON (75.8 ± 21.8 L·min-1 vs 64.1 ± 14.5 L·min-1, 64.1 ± 16.2 L·min-1, and 54.0 ± 12.5 L·min-1, respectively, P < 0.001). The peak values and oscillations of V̇O2 and VE in HIIE60 were higher compared with all other trials (P < 0.001). Blood lactate concentration was higher in HIIE60 compared with HIIE10, HIIE30, and CON from the fifth minute onward, reaching 12.5 ± 3.5, 7.2 ± 2.1, 7.9 ± 2.9, and 4.9 ± 1.6 mmol·L-1, respectively, at the end of exercise (P < 0.001). RPE was higher and affective responses were lower in HIIE60 compared with all other trials toward the end of exercise (P < 0.001).

CONCLUSIONS

These findings highlight the importance of bout duration in HIIE, since shorter bouts resulted in attenuated metabolic and cardiorespiratory responses, lower RPE and feelings of displeasure compared with a longer bout, despite equal total work, duration, and work-to-recovery ratio. These results may have implications for the prescription of HIIE in various populations.

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

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

Burpee Interval Training Is Associated With a More Favorable Affective Valence and Psychological Response Than Traditional High Intensity Exercise

Acute psychological responses to physical activity may help explain long-term adherence to it. Thus, we compared acute psychological responses to different exercise protocols with identical durations. Eighteen moderately active young adults [ Mage = 23, SD = 3 years; MVO2max (maximum oxygen consumption) = 42.8, SD = 4.3 mL·kg−1·min−1; MBMI (body mass index) = 24, SD = 2 kg·m−2] completed three low-volume exercise sessions in a crossover research design: (a) sprint interval training (SIT), (b) burpee interval training (BIT) requiring 10 × 5 second efforts with 35 seconds of passive recovery, and (c) a single bout of vigorous intensity continuous training (VICT) requiring 6 minutes and 5 seconds of running at ∼85% of peak heart rate (HRpeak). We assessed participants’ ratings of perceived exertion (RPE), affective valence, enjoyment, intention, preference, and self-reported recovery and wellness before, during, and after each session. BIT was associated with significantly greater enjoyment, preference, and exercise intention (at 5 × week) than VICT ( p ≤ .05). SIT elicited greater RPE ( M = 5.38, SD = 2.00) than both BIT ( M = 2.88, SD = 1.23) and VICT ( M = 3.55, SD = 1.38) ( p ≤ .05), and we observed a higher increase in RPE over time with SIT versus BIT ( p = .019). For affective valence, SIT ( M = 0.55, SD = 2.12) elicited a more aversive response than both BIT ( M = 2.55, SD = 1.09) and VICT ( M = 1.94, SD = 1.51) ( p ≤ .05), and there was a higher increase in this aversive response to SIT over time ( p < .05). Forty-eight-hour postexercise session muscle soreness was significantly lower with VICT than with BIT ( p = .03). Overall, BIT was associated with more positive psychological responses than SIT and VICT.

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.

Effect of aerobic exercise intensity on health-related quality of life in severe obesity: a randomized controlled trial

Background

Aerobic exercise is an important part of obesity treatment and may improve health-related quality of life (HRQOL). The objective of this study was to compare the effect of two different exercise programs on health-related quality of life in patients with severe obesity.

Methods

This was a single-center, open-label, randomized, parallel-group study comparing the effects of a 24-week moderate-intensity continuous training (MICT) program and a combined high-intensity interval training program with MICT (HIIT/MICT). The primary objective (specified secondary outcome) was to assess HRQOL by using the general health dimension of the Short Form Health Survey (SF-36). The secondary objectives were to assess other dimensional SF-36 scores, the impact of weight on the physical and psychosocial aspects of quality of life (IWQOL-Lite), and the burden of obesity-specific weight symptoms (WRSM).

Results

73 patients were enrolled and reported patient reported outcome measures, with 71 patients (55% females) allocated to either MICT (n = 34) or HIIT/MICT (n = 37). In the intention-to-treat analysis, general health scores increased between baseline and 24-week follow-up in both the HIIT/MICT group and the MICT group, with a mean change of 13 (95% CI 6–21) points and 11 (95% CI 5–17) points, respectively, with no difference between the groups. The effect sizes of these changes were moderate. The vitality and social functioning scores of SF-36, and the physical function and self-esteem scores of IWQOL-Lite increased moderately in both groups, with no difference between groups. The tiredness, back pain, and physical stamina scores based on WRSM showed moderate to strong changes in both the groups.

Conclusions

Patients who had completed a combined HIIT/MICT program did not experience larger improvements in general health compared with those completing a clean 24-week MICT program. Exercise may confer general health benefits independent of intensity.

Trials registration

Regional Committees for Medical and Health Research Ethics south east, Norway, October 23, 2013 (identifier: 2013/1849) and ClinicalTrials.gov December 8, 2014 (identifier: NCT02311738).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12955-022-01940-y.

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.

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.

Comparison of the Sustainability Effects of High-Intensity Interval Exercise and Moderate-Intensity Continuous Exercise on Cognitive Flexibility

This study examined the immediate and sustained effects of high-intensity interval exercise (HIIE) and moderate-intensity continuous exercise (MICE) on cognitive flexibility in young adults. Participants (n = 56) engaged in (1) a session of HIIE, involving 10 sets of one-minute treadmill running at an intensity targeting 90% heart rate reserve (HRR) interspersed with self-paced walking at 50% HRR; (2) a session of MICE, involving a 20 min treadmill running at an intensity of 40-59% HRR; and (3) a control session, involving 24 min of resting on separate days in a counterbalanced order. Using a more-odd shifting task, cognitive flexibility was assessed before the intervention (t0), immediately after the session (t1), and then at 30 min (t2) after the session. During the more-odd shifting task, the switch cost of response time (RT) immediately after the HIIE was significantly reduced compared to that before exercise, suggesting beneficial effects on cognitive flexibility. Additionally, the impacts of HIIE were maintained for 30 min post-exercise. However, improved cognitive flexibility was not observed until 30 min after the MICE intervention. HIIE might represent a time-efficient approach for enhancing cognitive flexibility.

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.

Effects of Exercise Structure and Modality on Physiological and Perceptual Responses to Exercise

ABSTRACT

Bogdanis, GC, Mallios, VJ, Katsikas, C, Fouseki, T, Holman, I, Smith, C, and Astorino, TA. Effects of exercise structure and modality on physiological and perceptual responses to exercise. J Strength Cond Res 35(9): 2427-2432, 2021-This study examined the effect of exercise mode and intensity on physiological and perceptual responses to exercise. Twelve active adults (6 men and 6 women, age = 21.7 ± 1.6 years) initially performed incremental testing on the treadmill (TM) and cycle ergometer (CE) to assess maximal oxygen uptake (V̇o2max) and ventilatory threshold (VT). During the next 4 visits in a randomized order, subjects performed 20 minutes of moderate-intensity continuous exercise (MICE) at an intensity 20% below VT on the TM (TMMICE) and cycle ergometer (CEMICE) as well as time-matched high-intensity interval exercise (HIIE; 10 1-minute bouts at workload equal to 20% above VT followed by 1-minute active recovery) on both modes (TMHIIE and CEHIIE). During exercise, gas exchange data, blood lactate concentration, and perceptual responses (rating of perceived exertion, affective valence, and enjoyment) were assessed. Heart rate (p < 0.001) and V̇o2 (p < 0.001) were higher in response to TMHIIE vs. CEHIIE as well as TMMICE vs. CEMICE. Blood lactate concentration was higher (p = 0.003) in response to CEHIIE vs. TMHIIE. The rating of perceived exertion was significantly higher (p < 0.001) in TMMICE compared with CEMICE which showed the most positive affective valence (p = 0.009). Enjoyment was similar across all bouts (p = 0.11). Treadmill-based HIIE leads to higher heart rate and V̇o2 vs. CEHIIE, although there was no difference in affective valence or enjoyment. Practitioners aiming to optimize the cardiorespiratory response to moderate or interval exercise in their clientele should recommend TM running rather than cycling.

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.

Neurophysiological Stress Response and Mood Changes Induced by High-Intensity Interval Training: A Pilot Study

This pilot study, conducted in advance of a future definitive randomized controlled trial, aimed to investigate the feasibility of using a HIIT-based intervention to induce neurophysiological stress responses that could be associated with possible changes in mood. Twenty-five active male college students with an average age of 21.7 ± 2.1 years, weight 72.6 ± 8.4 kg, height 177 ± 6.1 cm, and BMI: 23.1 ± 1.4 kg/m² took part in this quasi-experimental pilot study in which they were evaluated in two different sessions. In the first session, subjects performed a graded exercise test to determine the cycling power output corresponding to VO_2peak. The second session consisted of (a) pre-intervention assessment (collection of blood samples for measuring plasma corticotropin and cortisol levels, and application of POMS questionnaire to evaluate mood states); (b) exercise intervention (10 × 1-min of cycling at VO_2peak power output); (c) post-intervention assessment, and (d) 30-min post-intervention evaluation. Significant post-exercise increases in corticotropin and cortisol plasma levels were observed whereas mood states decreased significantly at this assessment time-point. However, a significant increase in mood was found 30-min after exercise. Finally, significant relationships between increases in stress hormones concentrations and changes in mood states after intense exercise were observed. In conclusion, our HIIT-based intervention was feasible to deliver and acceptable to participants. A single bout of HIIT induced acute changes in mood states that seems to be associated with hypothalamic-pituitary-adrenal axis activation.

Exercisers' Affective and Enjoyment Responses: A Meta-Analytic and Meta-Regression Review

Affective responses and enjoyment of exercise mediate exercise adherence, but previous research findings have failed to examine nuances that may moderate this relationship. We examined the effects of exercise on affective and enjoyment responses during and post exercise through a systematic literature review and meta-regression analysis. We searched major databases up to July 9, 2020 for studies evaluating healthy adults' acute and chronic responses to exercise, using either of The Feeling Scale or Physical Activity Enjoyment Scales. We calculated effect size (ES) values of 20 unique studies (397 participants; 40% females) as standardized differences in the means and expressed them as Hedges' g, together with the 95% confidence interval (95%CI). Among acute studies examining affective responses, we found a greater positive effect post exercise for continuous training (CT) compared to high intensity interval training (HIIT) (g = -0.61; 95%CI = -1.11, -0.10; p < .018), but there was no significant difference between these modes for effects during exercise. Subgroup analyses revealed that moderate, and not high intensity, CT, compared to HIIT, resulted in significantly greater positive affective responses (g = -1.09; 95%CI = -1.88, -0.30; p < .006). In contrast, enjoyment was greater for HIIT, compared to CT (g = 0.75; 95%CI = 0.17, -1.13; p = .010), but CT intensity did not influence this result. Among chronic studies, there was greater enjoyment following HIIT compared to CT, but these studies were too few to permit meta-analysis. We concluded that an acute bout of moderate intensity CT is more pleasurable, when measured post exercise than HIIT, but enjoyment is greater following HIIT, perhaps due to an interaction between effort, discomfort, time efficiency and constantly changing stimuli.

Sprint interval training (SIT) reduces serum epidermal growth factor (EGF), but not other inflammatory cytokines in trained older men

Purpose

The present study aimed to investigate the effect of age on circulating pro- and anti-inflammatory cytokines and growth factors. A secondary aim was to investigate whether a novel sprint interval training (SIT) intervention (3 × 20 s ‘all out’ static sprints, twice a week for 8 weeks) would affect inflammatory markers in older men.

Methods

Nine older men [68 (1) years] and eleven younger men [28 (2) years] comprised the younger group. Aerobic fitness and inflammatory markers were taken at baseline for both groups and following the SIT intervention for the older group.

Results

Interleukin (IL)-8, vascular endothelial growth factor (VEGF), and monocyte chemoattractant protein-1 (MCP-1) were unchanged for the older and younger groups at baseline (IL-8, p = 0.819; MCP-1, p = 0.248; VEGF, p = 0.264). Epidermal growth factor (EGF) was greater in the older group compared to the younger group at baseline [142 (20) pg mL⁻¹ and 60 (12) pg mL⁻¹, respectively, p = 0.001, Cohen's d = 1.64]. Following SIT, older men decreased EGF to 100 (12) pg mL⁻¹ which was similar to that of young men who did not undergo training (p = 0.113, Cohen's d = 1.07).

Conclusion

Older aerobically trained men have greater serum EGF than younger aerobically trained men. A novel SIT intervention in older men can shift circulating EGF towards trained younger concentrations. As lower EGF has previously been associated with longevity in C. elegans, the manipulative effect of SIT on EGF in healthy ageing in the human may be of further interest.

Interval training causes the same exercise enjoyment as moderate-intensity training to improve cardiorespiratory fitness and body composition in young Chinese women with elevated BMI

This study examined the effects of 12 weeks of sprint interval training (SIT), high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on cardiorespiratory fitness (peak oxygen uptake, VO_2peak), body composition and physical activity enjoyment in overweight young women. Sixty-six participants (age 21.2 ± 1.4 years, body mass index (BMI) 26.0 ± 3.0 kg·m^-2, body fat percentage 39.0 ± 2.8%) were randomly assigned to non-exercise control (CON), thrice-weekly SIT (80 × 6 s "all-out" cycling interspersed with 9 s rest), and HIIT (4 min cycling at 90% VO_2peak followed with 3 min recovery for ~ 60 min) or MICT (~ 65 min continuous cycling at 60% VO_2peak) with equivalent mechanical work (200/300 KJ). Compared to the CON group, all three training groups had significant and similar improvements in VO_2peak (~ +20%, d = 2.5-3.4), fat mass (~ -10%, d = 1.3-2.1) and body fat percentage (~ -5%, d = 1.0-1.1) after a 12-week intervention. Similar high levels of enjoyment were observed among groups for most (~70%) of the training sessions. The findings suggest that the three training regimes are equally enjoyable and could result in similar improvements in cardiorespiratory fitness and body composition in overweight/obese young women, but SIT is a more time-efficient strategy.

Recall of Affective Responses to Exercise: Examining the Influence of Intensity and Time

Affective responses to exercise are noted to be dynamic and frequently vacillate between positive and negative valence during physical activity. Recalled affect following exercise can influence anticipated affective responses to exercise and guide future behaviors. Research examining affective memory processes indicates that the recall of an experience can substantially differ from the actual experience and change over time. Grounded in the dual mode model (Ekkekakis, 2003), this study examines individuals' recall of exercise-related affect over a period of 2 weeks. Forty-two adults (26 women, 16 men; M_age = 29.64, SD = 5.69) completed two 20-min treadmill exercise trials in a randomized control crossover design; the trials were set either at a low or high exercise intensity based upon individuals' ventilatory threshold. Data analyses indicate that the affective responses to the low-intensity condition were evaluated more positively than in the high-intensity condition. Recalled affect fluctuated over a 2-week time period following both the low- and high-intensity exercise trials. A significant reduction at the 24-h recall measurement point was observed in both exercise intensity conditions. Implications for future research and health promotion interventions aiming to optimize affective responses to exercise are presented.

Psychological responses to HIIT and MICT over a 2-week progressive randomized trial among individuals at risk of type 2 diabetes

The purpose of this secondary analysis study was to examine the affective and social cognitive responses to low-volume high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) over a progressive two-week supervised intervention for individuals at risk of type 2 diabetes. Ninety-nine adults that were low-active and overweight were randomized into one of two exercise conditions and had affective and social cognitive measures assessed before, during, and after intervention. Increases over time in post-exercise enjoyment, attitudes towards exercise, and intentions to exercise were noted for both HIIT and MICT conditions (ps <.05). The patterns of change in acute affective responses over the two-week intervention were consistent for both conditions, with participants in MICT reporting more positive in-task affect and affective attitudes throughout (ps <.001). Positive correlational relationships between affective and social cognitive responses were revealed throughout the intervention (ps <.05), highlighting the relationship between reflexive responses and reflective cognitions. Research is warranted to determine whether findings are a consequence of familiarization with exercise, whether such findings are translatable to real-world environments and non-progressive exercise protocols, and whether these reflexive responses and reflective cognitions are predictive of future exercise behaviour for individuals at risk of type 2 diabetes.

Affective responses to high-intensity interval training with continuous and respite music

Music has been shown to enhance affective responses to continuous exercise, but the most effective application of music during interval exercise is poorly understood. This study examined two contrasting applications of music designed to assuage the decline in pleasure often experienced during high-intensity interval training (HIIT). In a repeated measures crossover design, 18 recreationally active participants (10 men and 8 women; M _age = 25.1 ± 5.1 years; M _BMI = 23.08 ± 2.01 kg/m 2; M VO_2max = 38.82 ± 10.73 ml/kg/min) completed three HIIT sessions (10 x 60 s efforts at 100% Wmax, separated by 75 s recovery) on a cycle ergometer. Participants completed two experimental conditions: respite music (applied only during the recovery periods), continuous music (applied throughout the entire HIIT session); and a no-music control condition. Results indicated that music did not influence affective valence during the work bouts or recovery periods of the HIIT sessions (ps >.05), but that listening to music continuously elicited greater post-task enjoyment (p =.032, d = 0.66) and remembered pleasure (p =.044, d = 0.5). This study is the first to investigate the application of music during a practical HIIT protocol and to compare the effects of respite versus continuous music during interval exercise.

Early intervention exercise training does not delay prostate cancer progression in Pten-/- mice

BACKGROUND

There is convincing evidence that men with advanced prostate cancer experience improved quality of life as a result of exercise therapy, although there is limited preclinical, and no clinical, data to directly support the notion that exercise training improves prostate cancer prognosis or outcome. The aim of this study was to investigate the effect of regular exercise training on the early stages of prostate cancer progression, as well as assessing whether alterations to prostate cancer metabolism are induced by exercise.

METHODS

Mice with prostate-specific deletion of Pten (Pten^-/- ) remained sedentary or underwent 6 weeks of endurance exercise training or high-intensity exercise training involving treadmill running. At the conclusion of the training period, the prostate lobes were excised. A portion of fresh tissue was used to assess glucose, glutamine, and fatty acid metabolism by radiometric techniques and a second portion was fixed for histopathology.

RESULTS

Despite the implementation of an effective exercise regime, as confirmed by improvements in running capacity, neither prostate mass, cell proliferation or the incidence of high-grade prostate intraepithelial hyperplasia or noninvasive carcinoma in situ were significantly different between groups. Similarly, neither glucose uptake, oxidation and de novo lipogenesis, glutamine oxidation, or fatty acid uptake, oxidation and storage into various lipids were significantly different in prostate tissue obtained from untrained and exercise trained mice.

CONCLUSIONS

These results show that 6 weeks of moderate or high-intensity exercise training does not alter substrate metabolism in the prostate or slow the progression of Pten-null prostate cancer. These results question whether exercise is a useful therapy to prevent or delay prostate cancer progression.

Reduced exertion high-intensity interval training (REHIT) in an adult with Cystic Fibrosis: A mixed-methods case study

Although aerobic capacity has been identified as an important predictor of mortality in Cystic Fibrosis (CF) individuals, many remain insufficiently active. As a 'lack of time' is a commonly cited barrier to exercise, reduced-exertion high-intensity interval training (REHIT) may provide a truly time-effective method to increase aerobic capacity. Six-weeks of REHIT in a CF individual was assessed by a cardiopulmonary exercise test (CPET) and individual perceptions described using a self-report narrative. Peak oxygen uptake (V ˙ O2peak) increased by 6% whilst pulmonary function remained unchanged. Qualitative data indicated social support and low-time commitment positively influenced adherence with fatigue and lack of enjoyment noted as a significant barriers. REHIT was demonstrated as a viable, manageable option for a CF individual with moderate-severe pulmonary limitation. Further research is needed to determine the efficacy of REHIT in a large representative sample to ascertain whether it represents an alternative treatment strategy.

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

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

A systematic review and meta-analysis of affective responses to acute high intensity interval exercise compared with continuous moderate- and high-Intensity exercise

There is evidence for the physical health benefits of high intensity interval exercise (HIIE), but its public health potential has been challenged. It is purported that compared with moderate-intensity continuous exercise (MICE) the high intensity nature of HIIE may lead to negative affective responses. This systematic review (PROSPERO CRD42017058203) addressed this proposition and synthesised research that compares affective responses to HIIE with MICE and vigorous intensity continuous exercise (VICE), during-, end-, and post-exercise. Searches were conducted on five databases, and findings from 33 studies were meta-analysed using random effects models or narratively synthesised. A meta-analysis of affect showed a significant effect in favour of MICE vs HIIE at the lowest point, during and post-exercise, but not at end, and the narrative synthesis supported this for other affective outcomes. Differences on affect between VICE vs HIIE were limited. Pooled data showed arousal levels were consistently higher during HIIE. For enjoyment there was a significant effect in favour of HIIE vs MICE, no difference for HIIE vs VICE at post-exercise, and mixed findings for during-exercise. Although the findings are clouded by methodological issues they indicate that compared to MICE, HIIE is experienced less positively but post-exercise is reported to be more enjoyable.

Affective and Enjoyment Responses to Short-Term High-Intensity Interval Training with Low-Carbohydrate Diet in Overweight Young Women

Low-carbohydrate diets (LCs) seem effective on weight reduction and maintenance. However, the affect and enjoyment of exercise during LCs is not clear. The purpose of the present study was to compare the psychological responses to high-intensity interval training (HIIT) and to moderate-intensity continuous training (MICT) during the consumption of a 4-week LC diet in overweight young women. With LCs (~10% carbohydrate, 65%–70% fat, 20%–25% protein), forty-three eligible women (age: 20.9 ± 3.1 years; body weight: 65.8 ± 8.2 kg) were randomly assigned to one of three groups: HIIT (10 sets of 6 s all-out cycling interspersed with 9 s of rest), MICT (30 min cycling at 50%–60% of peak oxygen consumption, V̇O_2peak) or no-exercise controls (CON). Anthropometric indices and V̇O_2peak were measured pre- and post-training. Feeling Scale (FS), Felt Arousal Scale (FAS), Exercise Enjoyment Scale (EES), and Physical Activity Enjoyment Scale (PACES) scores were collected before and immediately after each training session throughout the study. After intervention, all three groups reduced by more than 2.5 kg of body weight whereas both exercise groups improved ~15% V̇O_2peak. Participants in the HIIT and MICT group exhibited similar affect points as indicated by FS and FAS. Post-exercise enjoyment scores in PACES were lower in HIIT (73–78 points) than MICT (83–87 points) despite similarly positive responses being observed in EES (corresponding to ~4 points of a 7-point scale). Short-term LCs were effective in weight loss and exercise training had an additive improvement on cardiorespiratory fitness. The overweight young women had similar affect valence, arousal levels, and comparable pleasurable feelings to HIIT and MICT with LCs. Furthermore, as indicated by PACES, MICT was more enjoyable which may elicit better adherence, whereas HIIT with LCs seems to be more arduous despite its time-efficiency.

Type of Exercise Training and Training Methods

There is general agreement that exercise training leads to functional, morphological, and metabolic adaptations of different biological systems, thereby increasing overall physical performance and promoting good health. Thus, an active lifestyle is propagated in all age groups. However, not every exercise routine or workout is suitable for everyone. Inappropriate training can also pose risks, and too low or too high training intensity or volume often does not lead to the expected success. To ensure significant benefits, specific principles and strategies need to be considered and accustomed to the individual.This chapter summarizes the key exercise variables and training principles to consider when developing a training program to improve or maintain performance and health. In addition, the various steps for creating an individual training program are described, and an overview of the different training methods and training strategies is given.

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

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

Acute Demands and Recovery From Common Interval Training Protocols

Elmer, DJ, Barron, EN, and Chavez, JL. Acute demands and recovery from common interval training protocols. J Strength Cond Res XX(X): 000-000, 2019-The definition of interval training is quite broad, with no accepted procedure for classifying protocols with different workloads and work and recovery interval times. In addition, little is known about the differences in training load and recovery from common interval protocols. The purpose of this study was to evaluate the differences in acute physiological demands and perceived difficulty between 3 common interval training protocols and a moderate, continuous exercise session. Eight subjects completed the training sessions on a cycle ergometer in a randomized order, with at least 1 week between sessions: 30-second/4-minute, 1-minute/1-minute, 4-minute/3-minute, and a 45-minute continuous session. Metabolic variables were measured throughout exercise and 30 minutes of recovery. Training impulse (TRIMP), session-RPE, and RPE-training load were also measured. There were significant differences between protocols, including between interval training protocols, for average V[Combining Dot Above]O2 (p < 0.001) and heart rate (HR) (p = 0.02), total O2 consumption (p < 0.001), peak lactate (p < 0.001), TRIMP (p = 0.02), session-RPE (p = 0.01), and RPE-training load (p < 0.001). There were no significant differences between interval training protocols for peak V[Combining Dot Above]O2 or peak HR attained during exercise. There were also no differences in V[Combining Dot Above]O2 or HR after 5 or 30 minutes of recovery. Blood lactate was only significantly higher after 30 minutes of recovery from the 30-second/4-minute compared with the 4-minute/3-minute protocol (p = 0.001) and the 45-minute session (p < 0.001). These findings show a range of differences in acute physiological demands and perceptions from interval training protocols, which should be accounted for when planning training sessions or research studies or when interpreting past research.

Psycho-physiological responses to perceptually-regulated interval runs in hypoxia and normoxia

We investigated whether perceptually-regulated high-intensity intervals in hypoxia are associated with slower running velocities versus normoxia, when physiological responses and exercise-related sensations remain the same. Nineteen trained runners (33.4 ± 9.1 years) completed a high-intensity interval running protocol (4 × 4-min intervals at a clamped perceived rating exertion of 16 on the 6-20 Borg scale, 3-min passive recoveries) in either hypoxic (HYP; FiO₂ 15.0%) or normoxic (NOR; FiO₂ 20.9%) conditions. Participants adjusted to a progressively slower running velocity from interval 1-4 (-7.0%), and more so in HYP vs. NOR for intervals 2, 3 and 4 (-4.6%, -6.4% and - 7.9%, respectively; p < .01). Heart rate increased from interval 1-4 (+4.8%; p < .01), independent of condition. Arterial oxygen saturation was lower in HYP vs. NOR (86.0% vs. 94.8%; p < .01). Oxyhemoglobin (-23.7%) and total hemoglobin (-77.0%) decreased, whilst deoxyhemoglobin increased (+44.9%) from interval 1-4 (p < .01), independent of condition. Perceived recovery (-41.6%) and motivation (-21.8%) were progressively lower from interval 1-4, and more so in HYP vs. NOR for intervals 2, 3 and 4 (recovery: -8.8%, -24.2% and - 29.3%; motivation: -5.3%, -20.3% and - 22.4%, respectively; p < .01). Perceived breathlessness (+18.6%), limb discomfort (+44.0%) and pleasure (-32.2%) changed from interval 1-4, with significant differences (+21.8%, +11.3% and - 31.3%, respectively) between HYP and NOR (p < .01). Slower interval running velocities in hypoxia achieve similar heart rate and muscle oxygenation responses to those observed in normoxia when perceptually-regulated, yet at the expense of less favourable exercise-related sensations.

Sprint interval exercise versus continuous moderate intensity exercise: acute effects on tissue oxygenation, blood pressure and enjoyment in 18-30 year old inactive men

BACKGROUND

Sprint interval training (SIT) can be as effective, or more effective, than continuous moderate intensity exercise (CMIE) for improving a primary risk factor for cardiometabolic disease, low cardiorespiratory fitness (CRF). However, there has been no direct comparison in inactive individuals, of the acute effects of a session of SIT with a work-matched session of CMIE on local oxygen utilisation, which is a primary stimulus for increasing CRF. Furthermore, post-exercise blood pressure (BP) and enjoyment, if symptomatic and low, respectively, have implications for safety and adherence to exercise and have not been compared between these specific conditions. It was hypothesised that in young inactive men, local oxygen utilisation would be higher, while post-exercise BP and enjoyment would be lower for SIT, when compared to CMIE.

METHODS

A total of 11 inactive men (mean ± SD; age 23 ± 4 years) completed a maximal ramp-incremental exercise test followed by two experiment conditions: (1) SIT and (2) work-matched CMIE on a cycle ergometer on separate days. Deoxygenated haemoglobin (∆HHb) in the pre-frontal cortex (FH), gastrocnemius (GN), left vastus lateralis (LVL) and the right vastus lateralis (RVL) muscles, systemic oxygen utilisation (VO2), systolic (SBP) and diastolic (DBP) blood pressure and physical activity enjoyment scale (PACES) were measured during the experiment conditions.

RESULTS

During SIT, compared to CMIE, ∆HHb in FH (p = 0.016) and GN (p = 0.001) was higher, while PACES (p = 0.032) and DBP (p = 0.043) were lower. No differences in SBP and ∆HHb in LVL and RVL were found between conditions.

CONCLUSIONS

In young inactive men, higher levels of physiological stress occurred during SIT, which potentially contributed to lower levels of post-exercise DBP and enjoyment, when compared to CMIE.