Authors: Ruohan Zhang, Adam A. Malik, Hairul A. Hashim
Categories: Review Article, Physical health, Exercise intensity, Exercise duration, Enjoyment, Pleasurable
Source: Sports Medicine and Health Science
Authors: Ruohan Zhang, Adam A. Malik, Hairul A. Hashim
Obesity is a global public health challenge, and physical exercise, as a means of increasing energy expenditure, plays a crucial role in its management and reduction. High-intensity interval exercise (HIIE) is gaining popularity as an effective approach for improving physical health. However, its high intensity has been linked to negative emotional and affective responses among adults with excess body weight or adiposity. In this context, low-volume high intensity interval exercise (Lv-HIIE) emerges as a promising alternative to conventional HIIE. Despite its potential benefits, the literature on affective responses to Lv-HIIE in adults with excess body weight or affected by obesity remains limited.
This systematic review (PROSPERO registration no. CRD42024514591) evaluated the affective responses of Lv-HIIE among adults living with excessive weight or obesity. We compared emotional and affective response indicators before, during and after HIIE, moderate-intensity continuous exercise (MICE) and Lv-HIIE. The review adhered to the PRISMA guidelines and Cochrane recommendations, with data obtained from PubMed, Scopus, Web of Science and SPORTDiscus.
20 studies involving 472 participants met the inclusion criteria, with a mean age of (30.44 ± 6.93) years and a mean body mass index (BMI) of (30.26 ± 4.16) kg·m^−2^. The gender distribution comprised 288 females and 184 males, resulting in a female-to-male ratio of approximately 1.57. The findings indicate that adults with excess body weight or obesity exhibit more positive affective responses to HIIE compared to MICE following exercise. Although HIIE may require greater effort, participants reported greater enjoyment and pleasurable post-exercise than following MICE. Compared to traditional HIIE, Lv-HIIE has a shorter exercise duration, less frequent sessions and a potentially lower overall exercise volume.
These improvements reduce exertion during the exercise, fostering enhanced pleasure and enjoyment afterward.
The prevalence of excess body weight and adiposity is increasing globally. According to a recent report by the World Health Organization (WHO),^1^ approximately 937 million adults worldwide are living with excess adiposity, while 396 million are classified as having excessive weight. Over the past few decades, the prevalence of obesity has more than doubled in both developed and developing countries, encompassing over 70 nations, and this trend continues to increase in most regions.^2^ Moreover, the proportion of the global population classified as having excess body weight is increasing, contributing to the growing burden of obesity-related diseases, including cardiovascular diseases, diabetes, cancers, neurological disorders, chronic respiratory conditions, and digestive disorders.^3^ Consequently, excess body weight and obesity have emerged as crucial global public health issues, presenting significant challenges to healthcare systems.^4^
With the global rise in lifestyle-related chronic diseases such as excess adiposity and cardiovascular disease, the fitness industry has increasingly focused on developing safe, effective, and enjoyable fitness services to address public health needs.^5^ Given that regular exercise and physical activity provide numerous benefits for overall health and well-being,^6^ promoting accessible and sustainable exercise solutions has become a key priority. Studies have also consistently confirmed these benefits of regular exercise, particularly for individuals living with excessive weight or obesity. The findings are consistent with the latest exercise guidelines, which emphasize the importance of multi-component interventions in enhancing cardiometabolic health in adults with excess body weight or obesity.^7^ However, despite these benefits, participation in physical activity remains low globally. According to the WHO,^1^ 31% of adults and 80% of adolescents fail to meet the recommended levels of physical activity. Time constraints are consistently cited as the most significant barrier to engaging in physical activity, regardless of age or gender.8, 9, 10, 11 For adults with excess body weight or obesity aiming to reduce body fat, traditional exercise regimens, such as steady-state moderate-intensity activities (e.g., walking and jogging), are associated with minimal weight loss.^12^^,^^13^ Thus, there is a need for an exercise regimen that is both time-efficient and effective in reducing body fat, particularly for adults with excess adiposity or physical inactivity.^14^
In this context, high intensity interval exercise (HIIE) has become increasingly popular due to its time efficiency and ability to be quickly integrated into daily life. According to the American College of Sports Medicine (ACSM), HIIE has remained steadily in the top ten of the fitness trends lists since 2018 and rose to 6^th^ place in 2023.^15^ This growing trend is also reflected in a nationwide survey conducted in Turkey during the post-COVID-19 era, which found that exercise for weight loss became the most popular fitness activity.^5^ These are consistent with the increasing demand for time-efficient and effective workout strategies, reinforcing HIIE's role as a widely adopted solution. Given its growing recognition as an effective method for fat loss, HIIE has gained attention for its efficiency in promoting weight loss while requiring less time than traditional exercise methods.
Building on its popularity, HIIE is characterized by repeated bouts of short, near-maximal intensity aerobic exercise (> 85% maximal heart rate [HRmax]), alternated with active or passive rest periods (< 65% HRmax) that ensure sufficient recovery to repeat the same work effort.^15^ Emerging evidence highlights HIIE as a time-saving and efficient training approach that not only enhances fitness levels but also helps individuals achieve their health and body composition goals in less time.^8^^,^^16^ This exercise method is time-efficient and requires minimal equipment, making it suitable for a variety of settings. While HIIE offers many benefits, it is intense and requires careful attention to safety to sustain long-term participation. Exercise professionals should properly assess participants before the exercise begins and carefully monitor each person's intensity and form during the exercise to ensure safety.^15^ Ensuring safety is critical because it prevents injuries and increases the effectiveness of exercise.
However, despite its potential effectiveness and numerous benefits, HIIE presents unique challenges due to its rigorous nature. This type of exercise is generally better suited for people who already have a high capacity for physical activity and can tolerate intense, sustained exercise. For those unaccustomed to such exertion, particularly many adults living with excessive weight or obesity, HIIE may cause significant discomfort. Partly due to the more intense physical demands it places on individuals than moderate-intensity continuous exercise (MICE).17, 18, 19 Consequently, it has been argued that HIIE is not the optimal exercise for adults with excess body weight or adiposity. It may also exacerbate feelings of inadequacy or depression, which can prevent long-term adherence to an exercise program. Given these challenges, researchers have explored improved forms of HIIE to retain its benefits while reducing its intensity and physiological demands. One such approach is low-volume high intensity interval exercise (Lv-HIIE), which has emerged as a promising alternative to traditional HIIE. This approach offers comparable benefits when employing a less intense training regimen. A recent study found that Lv-HIIE may lead to similar or greater improvements in fitness and health outcomes compared to conventional aerobic exercise,^20^ including high-volume HIIE and MICE. This makes Lv-HIIE a potentially suitable option for adults living with excessive weight or obesity who have limited endurance, representing an effective tool for weight management and health improvement.^21^ While Lv-HIIE has potential benefits, its effects on affective responses remain unclear, especially given that individuals with excess adiposity may respond differently to high-intensity exercise than the general population.
According to latest review HIIE has been shown to significantly improve multiple psychological health-related indicators, and these improvements are at least as good as or better than those observed in adults with excess body weight or adiposity who performed moderate-intensity continuous exercise, this suggests that high intensity interval training (10.13039/501100023750HIIT) has significant potential in improving psychological adaptation.^22^ Especially for inactive women affected by obesity, by implementing a ten-month high-intensity interval neuromuscular training program, the psychological adaptability of this group can be significantly improved, their exercise behavior regulation and persistence can be enhanced, and weight loss can be effectively promoted.^23^ However, despite the research supporting the potential effectiveness of HIIE on psychological adaptation, there is still limited understanding of the specific effects of Lv-HIIE on the affective responses of adults with excess body weight or obesity. Affective responses play a key role in determining whether an individual starts and continues to participate in physical activities. These responses, such as pleasure, satisfaction, or discomfort during exercise are not only important indicators for evaluating the exercise experience, but also directly affect the individual's continued participation and long-term persistence.^24^ Therefore, it is particularly important to understand how Lv-HIIE affects the emotional experience of adults living with excessive weight or obesity.
It is well known that affective responses fluctuate before, during, and after exercise, switching between positive and negative states. When exercise induces pleasurable feelings, it can reinforce positive associations with physical activity, boost motivation, and improve long-term adherence.^25^ Conversely, when exercise causes discomfort or unpleasant feelings, it may evoke negative affective responses that can hinder engagement and reduce adherence over time. This fluctuation in affective responses is particularly evident in continuous exercise, where the well-documented inverse relationship between exercise intensity and pleasure exists - higher intensities are typically associated with less pleasure. Previous studies have indicated that sustained high-intensity exercise often leads to unpleasant sensations in affective responses.
However, this inverse relationship is less pronounced in HIIE,^26^ because affective responses are influenced by multiple factors such as exercise intensity, duration, and frequency.^27^ Furthermore, adults typically experience a decline in affective valence (i.e. pleasure or displeasure) during progressive exercise.^28^ However, this decline is not consistently observed with HIIE, potentially due to its intermittent nature, which provides periods of recovery.^29^ Recent studies have further confirmed this finding, which highlights the potential of interval training as an effective approach in exercise programs for both general and clinical populations, helping to enhance enjoyment, foster positive affective responses, and improve overall quality of life.^7^
The affective response to exercise can be further understood through the dual-modal theory, which states that the affective experience is closely related to the intensity of the exercise. According to this theory, affective responses to exercise are closely linked to exercise intensity. Low-to moderate-intensity exercise generally induces positive affect, whereas high-intensity exercise—particularly when it approaches or surpasses the anaerobic threshold—can lead to negative affective responses.
Numerous studies have investigated the effects of various exercise intensities and modes on affective responses.30, 31, 32, 33, 34, 35 However, most of these studies have focused on the physiological effects or psychological adaptations or traditional HIIE in healthy individuals, with limited attention given to the affective responses of adults with excess body weight or adiposity during Lv-HIIE. Furthermore, findings from existing studies are inconsistent. Although some research suggests that Lv-HIIE may elicit negative affective responses, other studies indicate that it may also enhance exercise enjoyment.^36^
Although the physiological benefits of HIIE in participants with excess body weight or obesity are well-established, its impact on affective responses during exercise remains unclear. Gaining insight into the affective experiences of participants living with excessive weight or obesity during Lv-HIIE is crucial for optimising exercise adherence and promoting long-term health benefits. This review synthesized existing literature on the affective responses of participants with excess body weight or obesity to Lv-HIIE. It examined how variables such as exercise intensity, duration and frequency influence affective outcomes. By exploring the emotional and psychological dimensions of exercise participation, this review analysed the mechanisms underlying adherence to Lv-HIIE among participants with excess body weight or obesity as well as investigated the design of effective, tailored exercise interventions that address their unique needs.
Prior to commencing the study, (1) informed consent from each participant was collected; (2) the study was reviewed and received approval to implement by the Universiti Sains Malaysia Human Research Ethics Committee (USM/JEPeM/22080549); and (3) the study was implemented in accordance with the Declaration of Helsinki.
This study was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and registered in the PROSPERO database (no. CRD42024514591).
We searched four electronic bibliographic databases—PubMed, Scopus, Web of Science and SPORTDiscus—to identify studies published up to February 15, 2024 using the following Boolean (“affect” OR “affective response” OR “emotional response” OR “affective” OR “emotion” OR “feeling” OR “enjoyment” OR “felt arousal”) AND (“low volume high intensity interval exercise” OR “low volume HIIE” OR “low volume high intensity interval training” OR “low volume HIIT” OR “high intensity interval exercise” OR “HIIE” OR “HIE” OR “high intensity interval training” OR “HIIT” OR “HIT” OR “interval exercise” OR “interval training”) AND (“overweight-obese” OR “overweight” OR “obese” OR “obesity”).
Table 1 presents the inclusion and exclusion criteria for study selection. Eligible studies were restricted to those involving human subjects, with findings published in English. No geographic restrictions were applied with respect to research eligibility. The reference lists of all retrieved articles were manually reviewed for potentially eligible studies. Additionally, the reference lists of included studies and relevant review articles identified during the initial search were examined to identify further studies for inclusion.Table 1Inclusion and exclusion criteria.Table 1Inclusion criteriaExclusion criteriaOverweight-to-obese individuals (BMI ≥ 23 kg·m^−2^)Weight or BMI not clearly reported or criteria for overweight and obesity not met (≤ 23 kg·m^−2^)Adults 18 years and overMinors under 18 years oldTraditional HIIE compared with low volume HIIE orHIIE (contain low volume) compared with continuous exerciseOnly one exercise intervention and no clear description of the intensity and volumeThe measurement includes at least one affective response (feeling, arousal, enjoyment)or other outcomes related to affectNo data or results reporting affective responsesIncludes randomized controlled trials,cohort studies, crossover studiesIncludes case-control studies, cross-sectional studies, qualitative researchPeer reviewed publications and master's and doctoral theses were eligible for inclusionCase reports, review articles, abstracts, and another non-originalPublished in EnglishPublished in other languagesHealthy individualsIndividuals with certain diseasesNotes. Abbreviations: HIIE: High intensity interval exercise; BMI: Body mass index.
The titles and abstracts of all studies were evaluated against the inclusion criteria. The screening process was conducted using Zotero. Initially, the retrieved literature was screened based on the information provided in the title and abstract. Studies that were clearly unrelated to the research topic or failed to meet the inclusion criteria were excluded at this stage. The full texts of the remaining studies were then obtained for a more detailed evaluation. Each study was thoroughly reviewed to determine whether it met the inclusion criteria, and those that did not meet the requirements were excluded from the final selection.
Data from the included studies were extracted using a data extraction form. The extracted data included participant characteristics (age, gender, weight, body mass index and health status), intervention details (exercise type, intensity, duration and frequency [e.g. sessions per week or month]), outcome measures (i.e. affective responses such as feelings, enjoyment and arousal) and study design (research methods, analysis and results). Data extraction was conducted independently by two reviewers to ensure accuracy and consistency. Following the completion of the data extraction process, all extracted data were thoroughly reviewed and verified to ensure completeness and accuracy.
The risk of bias was evaluated using the Cochrane Collaboration Risk of Bias Tool. This tool assesses potential sources of bias related to group allocation and randomisation, blinding of participants and assessors, handling of missing data and reporting biases. Additionally, it considers any other potential sources of bias present in the studies.
Grading of Recommendations Assessment, Development, and Evaluation (GRADE) profiler 3.6 was used to evaluate the quality of evidence,^37^ which was divided into high, intermediate, low and very low levels. The evaluation content included five risk of bias, inconsistency, indirectness, imprecision and publication bias.
The literature search identified 583 studies that potentially met the inclusion criteria. Fig. 1 presents the PRISMA flowchart outlining the study selection process. In total, 101 studies were identified in PubMed, 204 in Scopus, 183 in Web of Science and 115 in SPORTDiscus. After removing duplicates, 287 studies remained for further screening. Initial screening based on titles and abstracts retained 69 studies that met the inclusion criteria. Subsequently, 49 studies were excluded for the following 20 due to participant characteristics, 16 based on study outcomes, 5 due to the exercise intervention, 4 because they were reviews and 4 due to unavailability of the full text. Ultimately, 20 studies progressed to the final selection process. After excluding one study with unclear intervention protocols, 19 studies remained. Additionally, 1 study identified from other sources was included, resulting in a total of 20 studies meeting the inclusion criteria.Fig. 1Flow diagram of selected studies.Fig. 1
Table 2 presents the participant characteristics for the included studies. The studies collectively involved 472 participants, comprising 288 women and 184 men (female-to-male 1.57), with greater representation of women in studies focusing on participants with excess body weight or obesity. The participants had a mean age of (30.44 ± 6.93) years (range: 19.7–43.8 years) and a mean body mass index (BMI) of (30.26 ± 4.16) kg·m^−2^ (range: 23–39 kg·m^−2^), maximal oxygen consumption (V˙O2max) ranged from 17 to 44.3 mL·kg^−1^·min^−1^. Most studies (n = 15/20) recruited participants categorised as having excess body weight or obesity.38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52 Four studies recruited inactive participants,^33^^,^53, 54, 55 and one study focused on sedentary individuals.^56^ These studies also focused on participants living with excessive weight or obesity. Among the included studies, four specifically examined men,^42^^,^^46^^,^^47^^,^^50^ whereas six targeted women.^33^^,^^38^^,^^43^^,^^48^^,^^54^^,^^55^ All participants met the inclusion criteria of being free from major relevant diseases, such as cardiovascular conditions or affective disorders.Table 2Participants’ characteristics of selected studies.Table 2StudyGroupsSubjectsM/FAge (years)BMI (kg·m^−2^)V˙O2max (mL·kg^−1^·min^−1^)Other(Martinez et al., 2015)^53^Con IS (30/60/120)5M: 1122 ± 429 ± 328 ± 5Inactive5/5/5F: 9(Chu et al., 2021)^33^MICE15M: 022.07 ± 1.9528.03 ± 3.7528.59 ± 3.23InactiveHIIE15F: 30(Kong et al., 2016)^38^HIIT13M: 021.5 ± 0.425.8 ± 2.632.0 ± 6.6MVCT13F: 2620.5 ± 1.925.5 ± 2.132.0 ± 5.0(Ayob et al., 2023a)^39^P-HIIE10M: 826.7 ± 4.927.3 ± 1.327.4 ± 6.5–S-HIIE10F: 1226.6 ± 3.728.4 ± 1.126.2 ± 7(Kilpatrick, Lane et al., 2015)^40^CON HIIT (15/30/60)4M: 7–2834–4/4/4F: 9(Astorino et al., 2019)^36^TRAD10M: 037 ± 1239 ± 4.321 ± 3InactivePER9F: 1937 ± 839 ± 4.317 ± 2(Smith-Ryan, 2017)^41^HIIT(2min)21M: 2037.0 ± 12.130.8 ± 4.829.5 ± 7.9–HIIT(1min)21F: 2234.8 ± 12.427.1 ± 7.2(Ram et al., 2022)^42^MICT12M: 2826 ± 827.4 (4.0)32.9 ± 6.6–HIIT16F: 030 ± 628.1 (4.1)33.5 ± 7.0(Li et al., 2022)^43^RST14M: 0F: 6020.7 ± 1.7>2327.5 ± 3.4HIIE1201419.9 ± 1.726.0 ± 4.1HIIE901419.7 ± 1.028.1 ± 2.6MICE1420.7 ± 2.229.0 ± 2.9(Marillier et al., 2022)^44^MICT10M: 1447.8 ± 9.733.5 (11.4)22.6 ± 8.2**-HIIT10F: 648.5 ± 7.631.9 (5.7)23.2 ± 5.4(Vella et al., 2017)^45^MICT9M: 728.9 ± 8.133.1 ± 6.034.5 ± 2.1-HIIT8F: 1023.1 ± 6.629.9 ± 3.334.8 ± 2.9(Decker & Ekkekakis, 2017)^55^MICE12M: 039.25 ± 11.2334.96 ± 4.4619.05 ± 3.67InactiveHIIE12F: 24(Tsirigkakis et al., 2022)^46^HIIT108M: 1637.2 ± 9.529.8 ± 2.129.4 ± 2.4–HIIT608F: 040.2 ± 3.930.1 ± 2.632.5 ± 5.0(Farias-Junior et al., 2019)^47^MICE10M: 2128.9 ± 5.029.2 ± 3.8-HIIE11F: 0(Morton et al., 2017)^48^SS14M: 030.5 ± 6.835.1 ± 5.1–HIIT13F: 27(Wong et al., 2021)^49^Con5M: 524.2 ± 3.836.8 ± 4.624.2 ± 2.6HIIE5F: 5(Poon et al., 2020)^50^MICT12M: 2448.1 ± 5.225.6 ± 3.134.3 ± 6.0HIIT12F: 026.1 ± 1.632.5 ± 5.6(Ayob et al., 2023b)^51^S-HIIE12M: 826.7 ± 0.323–3028.8 ± 7.8P-HIIE12F: 1626.4 ± 6.4(Halvorson., 2016)^52^ConHIIT (60/90)4M: 831.4 ± 10.330.6 ± 2.644.3 ± 6.85/5F: 643.8 ± 8.928.9 ± 3.436.8 ± 12.4(Martinez., 2013)^56^ConIS (30/60/120)4M: 723 ± 429 ± 327 ± 6Sedentary10F: 7Notes. Abbreviations:** BMI: Body mass index; V˙O2max: Maximal oxygen consumption Con: Continuous exercise; HIIT: High intensity interval training; MICE: Moderate intensity continuous exercise; MICT: Moderate intensity continuous training; HIIE: High intensity interval exercise; MVCT: Moderate-to-vigorous intensity continuous training; P-HIIE: Prescribed HIIE; S-HIIE: Self-paced HIIE; TRAD: Traditional HIIT; PER: Periodized interval training; RST: Repeated sprint training; SS: Steady state; IS (30/60/120): Interval-Severe 30/60/120 s; HIIT (15/30/60): Interval 15/30/60 s; HIIT (2min): 2-min cycling with 1-min passive rest at a daily undulating intensity (80%–100% PO); HIIT(1 min): 1-min bouts with 1-min passive rest periods at 90% PO for 10 bouts; HIIE120: 1-min effort at 120% V˙O2peak; HIIE90: 4-min effort at 90% V˙O2peak; HIIT10: 48 × 10 s at 100% of PPO with 15 s of recovery; HIIT60: 8 × 60 s at 100% PPO with 90 s of recovery; HIIT(60/90): 80% APMHR and 60% APMHR every 60/90 s.
Table 3 presents the characteristics of the exercise interventions. The included studies utilised various parameters to adjust exercise sessions (e.g. Lv-HIIE, HIIE and MICE). These parameters included V˙O2max,^33^^,^^38^^,^^40^^,^^43^ peak heart rate,^42^^,^^48^ peak power output (PPO),^41^^,^^46^^,^^54^ heart rate reserve,^45^ maximal intensity,^33^^,^^44^ self-paced and prescribed intensity^39^^,^^51^ and ventilatory threshold.^55^Table 3Intervention characteristics of selected studies.Table 3StudiesExercise conditionsModeSessionDuration(min)HIIECEIntensity variableProtocolIntensity variableprotocol(Martinez et al., 2015)53AT-MCIS30IS60IS120AT-MC20 min –10% DTCycle ergometerH:24C:2024 × 30 s (60%) + 30 s(10%–20%)12 × 60 s (60%) + 60 s(10%–20%)6 × 120 s (60%)+120 s(10%–20%)(Chu et al., 2021)^33^Wmax9 × 45 s(Wmax) + 75 s recV˙O2max18 min 50%Cycle ergometer18(Kong et al., 2016)^38^V˙O2max60 × 8 s (max) + 12 s recV˙O2max40 min- (60%–80%)Cycle ergometerH: 20C: 40(Ayob et al., 2023a)^39^MAS(7–9) × 60 s 90% + 75 s rec–Treadmill16/18/20SELF(7–9) × 60 s self-paced + 75 s rec(Kilpatrick, Lane et al., 2015)^40^V˙O2peakINT-15INT-30INT-60V˙O2peak30 min-33%Cycle ergometerH: 20C: 3040 × 15 s (85%) + 15 s20 × 30 s (85%) + 30 s10 × 60 s (85%) + 60 s(Astorino et al., 2019)^36^PPOTRADPER–Cycle ergometerT: 19-26P: 25(6–10) × (20–120 s)(60%–110%) + (60–120 s) rec10 × 60 s(75%–85%) + 60 s rec(Smith-Ryan, 2017)^41^PO1-min2-min–Cycle ergometer20/1510 × 60 s (90%) + 60 s rec5 × 120 s (80%–100%) + 60 s(Ram et al., 2022)^42^HRpeak10 × 60 s (90%) + 60 s rec (15%)HRpeak30 min-(65%–75%)Cycle ergometerH: 20C: 30(Li et al., 2022)^43^V˙O2maxHIIE90HIIE120V˙O2maxRSTMICECycle ergometerH90: 26 ± 3H120: 19 ± 2MICT: 57 ± 84 min - 90% 3 min rec1 min - 120% 1.5 min rec6 s spri9 s rest12 weeks60% V˙O2(Marillier et al., 2022)^44^WRpeak(16–22) × 60 s - 100% +60 s recWRpeak(32–44) min - 50%Cycle ergometerH: 16-22C: 32-44(Vella et al., 2017)^45^HRR10 × 60 s (75%–80%) +60 s (35%–40%) recHRR20 min –(55%–59%)Cycle ergometer20(Decker & Ekkekakis, 2017)^55^VT4 × 3 min (115%) +2 min (85%) recVT25 min –90 %Cycle ergometerH: 20C: 25(Tsirigkakis et al., 2022)^46^PPOHIIE10HIIE60**-**Cycle ergometer2048 × 10 s 100% + 15 s rec8 × 60 s 100% + 90 s rec(Farias-Junior et al., 2019)^47^Vmax10 × 60 s (100%) + 60 s recV˙O2reserve20 min – (55%–59%)Cycle ergometerH: 20C: 20(Morton et al., 2017)^48^HRmax8 × 3 min (60%–70%) +1 min (80%–90%)HRmax32 min – (80%–90%)Cycle ergometer32(Wong et al., 2021)^49^WRmax8 × 30 s 80% + 45 s recVthCEbelowCEaboveCycle ergometerH: 10C: 122 × 6 min +15 min rec(Poon et al., 2020)^50^HRmax10 × 60 s running (80%–90%) + 60 s recHRmax50 min- walking (65%–70%)Cycle ergometerH: 20C: 50(Ayob et al., 2023b)^51^MAS6 × 60 s 90% + 75 s rec–Treadmill13.5SELF6 × 60 s self-paced + 75 s rec(Halvorson., 2016)^52^APMHRHIIE60HIIE90APMHR45 min–60%Cycle ergometerH: 20/21C: 4510 × 60 s (80%↔60%)7 × 90 s (80%↔60%)(Martinez., 2013)^56^DTIS30IS60IS120DT20 min- 10%Cycle ergometerH: 12C: 2024 × 30 s 60%12 × 60 s 60%6 × 120 s 60%Notes. Abbreviations: HIIE: High intensity interval exercise; CE: Continuous exercise; AT-MC: Anaerobic threshold and maximal capacity; Wmax: Maximal intensity; V˙O2max: Maximal oxygen consumption; MAS: Maximal aerobic speed; SELF: Self-paced; PPO: Peak power output; PO: Power output; HRpeak: Maximal heart rate; WRpeak: Peak work rate; HRR: Heart rate reserve; VT: Ventilatory threshold; Vmax: Maximal treadmill velocity; HRmax: Maximal heart rate; WRmax: Maximal work rate; APMHR: Age predicted maximal heart rate; DT: Specific exercise intensities of delta; IS: Interval-Severe; Recovery; INT: Interval; TRAD: traditional HIIT; PER: Periodized interval training; Vth: Ventilatory threshold; IS30: Interval-Severe 30 s; IS60: Interval-Severe 60 s; IS120: Interval-Severe 120 s; INT-15: Interval 15 s; INT-30: Interval 30 s; INT-60: Interval 60 s.
One study compared three exercise modes, namely HIIE, MICE and vigorous-intensity continuous exercise (VICE), as well as repeated sprint training and different HIIE intensities—HIIE120 (120% V˙O2max) and HIIE90 (90% V˙O2max)—against MICE.^43^ Three studies compared two exercise HIIE with MICE and VICE, alongside control (CON), HIIE30, HIIE60 and HIIE120;^53^ CON with HIIT15, HIIT30 and HIIT60;^40^ and CON with HIIT30, HIIT60 and HIIT120.^56^ Eleven studies focused solely on comparing HIIE and MICE.^33^^,^^38^^,^^42^^,^^44^^,^^45^^,^47, 48, 49, 50^,^^52^^,^^55^ Additionally, five studies exclusively examined HIIE interventions.^37^^,^^39^^,^^41^^,^^46^^,^^51^
Regarding exercise instruments, 18 of the 20 selected studies utilised a cycle ergometer, while the remaining 2 studies used a treadmill. Among the 20 studies, 14 included exercise controls for Lv-HIIE, whereas four studies exclusively focused on interval exercise without incorporating continuous exercise protocols. Four studies examined three different HIIE intensities, and two studies explored two distinct MICE intensities. The duration of interval exercise interventions ranged from 13.5 to 32 min, with 20 min being the most frequently implemented. Conversely, continuous exercise interventions lasted between 12 min and 57 min. Notably, these recorded times excluded warm-up and cool-down periods.
Affective response outcome measures in research studies typically assess how individuals feel as a result of an intervention or experience. Table 4 summarizes the detailed results for measuring affective responses, enjoyment responses, and perceived activation. The most commonly used measure of affective responses is the Feeling Scale (FS), employed in 14 studies.^36^^,^^39^^,^^40^^,^42, 43, 44^,^46, 47, 48^,^51, 52, 53^,^^55^^,^^56^ The most frequently used measure of enjoyment response, specifically for physical activity enjoyment, is the Physical Activity Enjoyment Scale (PACES), utilised in 15 studies.^36^^,^^38^^,^^39^^,^42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53^,^^55^ For measuring exercise enjoyment, the Exercise Enjoyment Scale (EES) was applied in five studies.^40^^,^^41^^,^^52^^,^^53^^,^^56^ The most frequently used measure of perceived activation levels is the Felt Arousal Scale (FAS), although it has only been used in two studies.33, 44Table 4Affective response outcome measures.Table 4StudiesVariableExercise conditionMeasuretimeHIIECE(Martinez et al., 2015)^53^FSIS30IS60IS1203.0 ± 1.4Pre-During-Post3.7 ± 1.23.6 ± 1.43.1 ± 1.8EES3.5 ± 1.53.5 ± 1.32.7 ± 1.72.8 ± 1.6DuringPACES91 ± 1498 ± 1583 ± 2482 ± 19Post(Chu et al., 2021)^33^FAS(3.03 ± 1.56) – (5.43 ± 1.72) – (5.50 ± 1.94)(2.80 ± 1.71) – (4.23 ± 1.78) – (4.3 ± 1.62)Pre-During-Post(Kong et al., 2016)^38^PACESHIIE > MVCTDuring(Ayob et al., 2023a)^39^FSP-HIIES-HIIEPre-During-PostP-HIIE < S-HIIEPACES(111 ± 9 [s1]) – (117 ± 6 [s8]) – (117 ± 7 [s15])(112 ± 12 [s1]) – (116 ± 6 [s8]) – (120 ± 8 [s15])Post(Kilpatrick, Lane et al., 2015)^40^FSINT-15INT-30INT-60During-postINT-15/INT-30 > INT-60(1.7 ± 1.7) - (0.6 ± 1.8)EESINT-15/INT-30 > INT-60(3.3 ± 1.1) - (2.8 ± 1.4)During-post(Astorino., 2019)^36^TRADPERFS0.4 ± 1.81.8 ± 1.2Pre-During-PostPACES74.75 ± 16.75–During-Post(Smith-Ryan, 2017)^41^EES1-min2-minPre-during-postday1-day2 < day3 day9 (max)(Ram et al., 2022)^42^FS(2.3 ± 0.9) – (2.69 ± 0.9)(1.75 ± 1.2) – (2.09 ± 1.1)Pre-postPACES4.4 ± 0.44.3 ± 0.3Post(Li et al., 2022)^43^PACESHIIE90HIIE120RSTMICEPost96.8 ± 13.992.5 ± 11.4–80.8 ± 11.8FS1.5 ± 1.40.2 ± 1.2––During(Marillier et al., 2022)^44^FS(3.7 ± 1.6) – (2.9 ± 1.5) – (3.4 ± 1.3)(3.1 ± 2.0) – (2.4 ± 2.5) – (2.4 ± 2.5)Pre-During-PostFAS(3.0 ± 2.2) – (3.2 ± 1.4) -(3.4 ± 1.8)(3.7 ± 1.7) – (3.6 ± 1.3) – (3.6 ± 1.7)Pre-During-Post(Vella et al., 2017)^45^PACES100.1 ± 4.3100.3 ± 4.4Post(Decker & Ekkekakis, 2017)^55^FS−0.04 ± 1.941.13 ± 1.34Pre-During-PostPACES82.75 ± 21.7690.79 ± 22.60Post(Tsirigkakis et al., 2022)^46^HIIT10HIIT60–FSHIIT10 > HIIT60(3.0 ± 1.1 [w1 2]) – (2.2 ± 0.8 [w5 6]) – (2.1 ± 0.9 [w7 8])Pre-During-PostPACESHIIT10 > HIIT60Post(Farias-Junior et al., 2019)^47^FS−3.1 ± 1.80.8 ± 1.8Pre-During-postPACES106.0 ± 16.596 ± 14.5Post(Morton et al., 2017)^48^FSComplete: (2.88 ± 1.19 [w5]) – (3.82 ± 0.63 [w16])Non-complete: (2.91 ± 1.77 [w5]) – (3.16 ± 1.18 [w16])(5.0 ± 0 [w5]) – (5.0 ± 0 [w16])(4.08 ± 0.86 [w5]) – (3.88 ± 1.13 [w16])Pre-post(Wong et al., 2021)^49^CEbelowCEabovePACES66.1 ± 9.766.8 ± 4.466.3 ± 6.7Post(Poon et al., 2020)^50^PACES111.4 ± 9.4105.7 ± 14.7Post(Ayob et al., 2023b)^51^FSP-HIIES-HIIEPre-During1 ± 0.82.58 ± 1.5PACES117 ± 7120 ± 8Post(Halvorson, 2016)^52^EESHIIT60HIIT904.5 ± 1.1During4.4 ± 0.64.5 ± 0.6FS3.25 ± 1.353.75 ± 0.93.4 ± 1.05PostPACES5.2 ± 0.75.65 ± 0.64.85 ± 0.9Post(Martinez, 2013)^56^PACESIS30IS60IS12081 ± 22Post91 ± 17101 ± 143.6 ± 1.43.9 ± 0.83.4 ± 1.55 ± 27 ± 33.8 ± 1.43.2 ± 1.6FS3.1 ± 1.4Pre-During-postEES2.95 ± 1.4DuringNotes. Abbreviations: HIIE: High intensity interval exercise; HIIT: High intensity interval training; CE: Continuous exercise; FS: Feeling scale; PACES: Physical activity enjoyment scale; EES: Exercise enjoyment scale; FAS: Felt arousal scale IS: Interval-severe; MVCT: Moderate-to-vigorous intensity continuous training; P-HIIE: Prescribed HIIE; S-HIIE: Self-paced HIIE; INT: Interval TRAD: Traditional HIIT; PER: Periodized interval training RST: Repeated sprint training; MICE: Moderate intensity continuous exercise; IS30: Interval-Severe 30 s; IS60: Interval-Severe 60 s; IS120: Interval-Severe 120 s; INT-15: interval 15 s; INT-30: interval 30 s; INT-60: interval 60 s.
Table 5 summarizes the findings for comparison of affective valence (pleasure or displeasure; HIIE vs. MICE and Lv-HIIE vs. HIIE), as measured using the FS.^57^ The FS employs an 11-point bipolar scale, ranging from “Very Good” (+5) to “Very Bad” (−5), and is commonly used to assess affective feelings before, during, and after exercise.Table 5Feeling scale (FS).Table 5StudyExercise (Intensity/duration)MeasuretimeHIIECE(Martinez et al., 2015)^53^SI 3 024 minSI6024minSI12024min20 min 10%Pre-During-Post3.7 ± 1.23.6 ± 1.43.1 ± 1.83.0 ± 1.4(Ayob et al., 2023a)^39^P-HIIE (16–20 min)S-HIIE (16–20 min)–Pre-During-PostP-HIIE < S-HIIE(Kilpatrick, Lane et al., 2015)^40^INT15(20 m)INT30(20 m)INT60(20 m)–During-PostINT15/INT30 > INT60(1.7 ± 1.7) – (0.6 ± 1.8)(Astorino et al., 2019)^36^TRAD(60%–110%) (19–26 m)PER(75%–85%) (25 m)–Pre-During-Post0.4 ± 1.81.8 ± 1.2(Ram et al., 2022)^42^(20 min)-60 s (90%) - 60 s (15%) rec(30 min)-(65%–75%)Pre-Post(2.3 ± 0.9) – (2.69 ± 0.9)(1.75 ± 1.2) – (2.09 ± 1.1)(Li et al., 2022)^43^HIE90(26 min)HIIE120(19 min)–During1.5 ± 1.40.2 ± 1.2(Marillier et al., 2022)^44^(16–22 min)60 s 100% - 60 s rec(32–44min)50%(3.7 ± 1.6) – (2.9 ± 1.5) – (3.4 ± 1.3)(3.1 ± 2.0) – (2.4 ± 2.5) – (2.4 ± 2.5)Pre-During-Post(Decker & Ekkekakis, 2017)^55^3 min (115%) – 2 min (85%) rec (20 min)25 min - 90%Pre-During-Post−0.04 ± 1.941.13 ± 1.34(Tsirigkakis et al., 2022)^46^HIIT10 (20 min)HIIT60 (20 min)–Pre-During-PostHIIT10 > HIIT60HIIT60: (3.0 ± 1.1 [w1 2]) – (2.2 ± 0.8 [w5 6]) – (2.1 ± 0.9 [w7 8])(Farias-Junior et al., 2019)^47^60 s 100%-60 s rec (20 min)20 min-(55%–59%)Pre-During-Post−3.1 ± 1.80.8 ± 1.8(Morton et al., 2017)^48^3 min (60%–70%)-1 min (80%–90%) (32 min)32 min (80%–90%)Pre-postComplete: (2.88 ± 1.19 [w5]) – (3.82 ± 0.63 [w16])Non-complete: (2.91 ± 1.77 [w5]) – (3.16 ± 1.18 [w16])Complete)5.0 ± 0 [w5]) – (5.0 ± 0 [w16])Non-complete: (4.08 ± 0.86 [w5]) – (3.88 ± 1.13 [w16])(Ayob et al., 2023b)^51^P-HIIE (13.5 min)S-HIIE (13.5 min)–Pre-during1 ± 0.82.58 ± 1.5(Halvorson, 2016)^52^HIIT60 (20 min)HIIT90 (21 min)45 min-60%Post3.25 ± 1.353.75 ± 0.93.4 ± 1.05(Martinez, 2013)^56^IS30(12 m)IS60 (12 m)IS120 (12 m)20 min-10%Pre-During-Post3.6 ± 1.43.9 ± 0.83.4 ± 1.53.1 ± 1.4Notes. Abbreviations: IS30: Interval-Severe 30 s; IS60: Interval-Severe 60 s; IS120: Interval-Severe 120 s; P-HIIE: Prescribed HIIE; S-HIIE: Self-paced HIIE; INT-15: Interval 15 s; INT-30: Interval 30 s; INT-60: Interval 60 s; TRAD: Traditional HIIT; PER: Periodized interval training.
Eight studies examined affective valence before, during, and after HIIE and MICE using the FS. In five studies, participants with excess body weight or obesity reported higher FS scores (more positive affective responses) for HIIE compared to MICE at all time points. Specifically, during low-to moderate-intensity HIIE (e.g., 60% peak power, 90% peak heart rate, 100% peak work rate, 80% age-predicted HRmax, or 60% maximal capacity), participants experienced more positive feelings than during MICE. However, three studies found the FS scores for MICE were higher than those for moderate-to-vigorous HIIE (e.g., 115% ventilatory threshold,[60%–70%] + [80%–90%] HRmax, or 100% maximal treadmill velocity). In fact, two of these studies reported negative FS scores during HIIE, suggesting unpleasant feelings. These findings may be attributed to the higher intensity levels (100%–115% of heart rate) employed in these interventions. Additionally, one study noted that the incomplete HIIE intervention might have affected outcomes, possibly due to differences in exercise duration between HIIE and MICE. Participants also reported challenges with sustaining long-term high-intensity exercise, which contributed to poorer affective experiences during HIIE sessions. In general, for adults living with excess body weight or obesity, HIIE tends to elicit more positive affective responses than MICE, as long as the intensity is appropriate and large loads and extended durations are avoided.
According to the results of six studies examining feelings before, during and after Lv-HIIE and traditional HIIE, participants performing Lv-HIIE consistently reported higher FS scores compared to those undergoing traditional high-intensity HIIE. Participants with excess body weight or obesity demonstrated a more positive affective response to Lv-HIIE interventions. Two studies further highlighted that within Lv-HIIE protocols, training programmes with similar exercise intensity but fewer cycles and longer exercise durations elicited higher FS scores. For instance, in one study, the FS score for HIIT60 (10 × 60-s intervals at 80%–60% intensity over 20 min) was 3.25 ± 1.35, whereas the FS score for HIIT90 (7 × 90-s intervals at 80%–60% intensity over 21 min) was 3.75 ± 0.9.^52^ Another study reported an FS score of 3.6 ± 1.4 for IS30 (24 × 30-s intervals at 60% intensity over 12 min), compared to 3.9 ± 0.8 for IS60 (12 × 60-s intervals at 60% intensity over 12 min).^56^ These findings suggest that when designing HIIE interventions for adults with excess body weight or obesity, it is critical to identify the optimal intensity and interval structure to maximise positive affective responses.
Table 6 summarizes the findings on participants' exercise enjoyment, assessed using PACES.^58^ This 18-item scale, scored on a 7-point bipolar scale, evaluates enjoyment responses post-exercise. Example items include statements such as “It's not very refreshing/It's very refreshing.” Scores for all items are summed to provide a total enjoyment score (out of 126) for each exercise condition. Enjoyment was measured 10 min post-exercise across studies.Table 6Physical activity enjoyment scale (PACES).Table 6StudyExercise (Intensity/duration)Measure timeHIIECE(Martinez etal.,2015)^53^SI3024 minSI6024 minSI12024 min20 min-10%Post91 ± 1498 ± 1583 ± 2482 ± 19(Kong et al., 2016)^38^8 s (max) 20 min40 min-(60%–80%)DuringHIIT ≫ > MVCT(Ayob et al., 2023a)^39^P-HIIE(16–20 min)S-HIIE(16–20 min)–Post(111 ± 9 [s1]) - (117 ± 6 [s8]) – (117 ± 7 [s15])(112 ± 12 [s1]) – (116 ± 6 [s8]) – (120 ± 8 [s15])(Astorino et al., 2019)^36^TRAD(60%–110%)(19–26 m)PER(75%–85%) (25 m)–During-Post74.75 ± 16.75–(Ram et al., 2022)^42^(60 s [90%]) – (60 s [15%] rec [20 min])30 min - (65%–75%)Post4.4 ± 0.44.3 ± 0.3(Li et al., 2022)^43^HIE90(26 min)HIIE120(19 min)RSTMax 4 mMICE60% 57 mPost96.8 ± 13.992.5 ± 11.4–80.8 ± 11.8(Vella et al., 2017)^45^60 s (75%–80%) (20 min)20 min - (55%–59%)Post100.1 ± 4.3100.3 ± 4.4(Decker & Ekkekakis, 2017)^55^(3 min [115%]) – (2 min [85%] rec [20 min])25 min - 90%Post82.75 ± 21.7690.79 ± 22.60(Tsirigkakis et al., 2022)^46^HIIT10(20 min)HIIT60(20 min)–PostHIIT10 > HIIT60(Farias-Junior et al., 2019)^47^60 s 100% - 60 s rec (20 min)20 min - (55%–59%)Post106.0 ± 16.596 ± 14.5(Wong et al., 2021)^49^30 s 80% (10 min)CEbelowCEabovePost66.1 ± 9.766.8 ± 4.466.3 ± 6.7(Poon et al., 2020)^50^60 s (80%–90%) 20 min50 min - (65%–70%)Post111.4 ± 9.4105.7 ± 14.7(Ayob et al., 2023b)^51^P-HIIE(13.5 min)S-HIIE(13.5 min)–Post117 ± 7120 ± 8(Halvorson, 2016)^52^HIIT6020 minHIIT9021 min60%45 minPost5.2 ± 0.75.65 ± 0.64.85 ± 0.9(Martinez., 2013)^56^IS30(12 m)IS60(12 m)IS120(12 m)20 min - 10%Post91 ± 17101 ± 1484 ± 2481 ± 22Notes. Abbreviations: IS30: Interval-Severe 30 s; IS60: Interval-Severe 60 s; IS120: Interval-Severe 120 s; TRAD: Traditional HIIT; PER: Periodized interval training; P-HIIE: Prescribed HIIE; S-HIIE: Self-paced HIIE RST: Repeated sprint training; MVCT: Moderate-to-vigorous intensity continuous training; MICE: Moderate-intensity continuous exercise.
Data from 11 studies examining physical activity enjoyment after HIIE and MICE were analysed. Among the seven data sets, the PACES scores for HIIE were significantly higher than those for MICE, indicating that participants with excess body weight or obesity experienced greater enjoyment following HIIE. In three studies, PACES scores for HIIE and MICE were nearly identical. Given these comparable outcomes, the time efficiency of HIIE may make it a more practical exercise choice compared to MICE. However, two studies reported higher PACES scores for MICE than for HIIE. One HIIE intervention utilised an intensity of 115% of the ventilatory threshold, and the other involved full-effort sprints on an incline, both of which may have been too demanding for participants living with excessive weight or obesity to sustain comfortably. Overall, moderating the intensity of HIIE to a manageable level appears to enhance physical enjoyment among adults with excess body weight or obesity., making it a favourable alternative to MICE.
Data from six studies were analysed to examine physical activity enjoyment following Lv-HIIE and traditional HIIE. According to the results, four studies found that with the same intensity of HIIE, shorter rest intervals, even with a higher number of cycles, led to a more enjoyable exercise experience. Overall, intervals of 60–90 s appeared to produce the best results. In one study, HIIE with 10-s intervals at 100% PPO elicited greater physical activity enjoyment compared to HIIE with 60-s intervals. This suggests that to optimise the exercise experience, it is most effective to maintain an intensity of 60%–90% PPO. Two studies reported similar PACES scores when comparing HIIE at 90% maximal aerobic speed intensity and self-paced intensity, indicating that both approaches provide comparable enjoyment. In general, maintaining exercise intensity at 60%–90% of heart rate, with intervals of 60–90 s, appears to offer the most enjoyable exercise experience. This is consistent with the principles of Lv-HIIE. Compared to traditional long-duration, high-intensity HIIE, moderate-intensity, short-duration Lv-HIIE tends to result in greater post-exercise enjoyment.
Table 7 presents the findings from comparisons of HIIE vs. MICE and Lv-HIIE vs. HIIE regarding enjoyment during exercise, as measured on the EES developed.^59^ Participants responded to the “Use the following scale to indicate how much you are enjoying this exercise session,” using a 7-point Likert scale ranging from 1 (not at all) to 7 (extremely).Table 7Exercise enjoyment scale (EES).Table 7StudyExercise (Intensity/duration)Measure timeHIIECE(Martinez et al., 2015)^53^SI30 (24 min)SI60 (24 min)SI120 (24 min)20 min 10%During3.5 ± 1.53.5 ± 1.32.7 ± 1.72.8 ± 1.6(Kilpatrick, Lane et al., 2015)^40^INT15 (20 m)INT30 (20 m)INT60 (20 m)–During-postINT-15/INT-30 > INT-60(3.3 ± 1.1) – (2.8 ± 1.4)(Smith-Ryan, 2017)^41^1-min (90%) 20 m2-min (80%–100%) 15 m–Pre-During-Post1-min ≈ 2-min(Halvorson, 2016)^52^HIIT60 (20 min)HIIT90 (21 min)45 min 60%During4.4 ± 0.64.5 ± 0.64.5 ± 1.1(Martinez, 2013)^56^IS30 (12 m)IS60 (12 m)IS120 (12 m)20 min 10%During3.8 ± 1.43.8 ± 1.43.2 ± 1.62.95 ± 1.4Notes. Abbreviations: IS30: Interval-Severe 30 s; IS60: Interval-Severe 60 s; IS120: Interval-Severe 120 s; P-HIIE: Prescribed HIIE; S-HIIE: Self-paced HIIE; INT-15: Interval 15 s; INT-30: Interval 30 s; INT-60: Interval 60 s; HIIT60: 80% APMHR and 60% APMHR every 60 s; HIIT90: 80% APMHR and 60% APMHR every 90 s.
Data from three studies examining exercise enjoyment following HIIE and MICE revealed that in two of the studies, EES scores for HIIE were generally higher than those for MICE, with participants reporting greater enjoyment during HIIE. In the third study, the EES scores for both HIIE and MICE were similar; however, overall, enjoyment during HIIE was still rated more favourably than during MICE.
Data from three studies examining physical activity enjoyment following Lv-HIIE and traditional HIIE revealed consistent findings across two studies that tested different interval durations in HIIE. The study results indicated that the longest intervals corresponded with the lowest EES scores, while the EES scores for the other two shorter intervals were similar. In both studies, there were no significant differences in EES scores between the two groups using different interval lengths during HIIE. Overall, compared to traditional HIIE with longer intervals, Lv-HIIE with 90-s intervals yielded greater exercise enjoyment for adults with excess body weight or obesity.
Table 8 illustrates the findings comparing HIIE and MICE in terms of arousal. The concept of the “arousal scale” typically refers to measuring physiological or psychological arousal. In these studies, perceived activation levels were assessed using the FAS,^60^ where participants rated their arousal on a 6-point scale ranging from 1 (“low arousal”) to 6 (“high arousal”).Table 8Felt arousal scale (FAS).Table 8StudyExercise (Intensity/duration)MeasuretimeHIIECE(Chu et al., 2021)^33^18 min45 s (Wmax) 75 s rec18 min50%Pre-During-Post(3.03 ± 1.56) – (5.43 ± 1.72) – (5.50 ± 1.94)(2.80 ± 1.71) – (4.23 ± 1.78) – (4.3 ± 1.62)(Marillier et al., 2022)^44^(3.0 ± 2.2) – (3.2 ± 1.4) – (3.4 ± 1.8)(3.7 ± 1.7) – (3.6 ± 1.3) – (3.6 ± 1.7)Pre-During-PostNotes. Abbreviations: HIIE: High intensity interval exercise; CE: Continuous exercise; Wmax: Maximal intensity.
Data from two studies examining perceived activation levels after HIIE and MICE, with one showing that throughout the pre-, during- and post-exercise stages, the FAS scores for HIIE were consistently higher than those during MICE. This suggests that adults with excess body weight or obesity experienced a higher level of activity engagement during HIIE compared to MICE. The other data showed no significant difference in the level of perceived activation after HIIE and MICE. Thus, HIIE appears to have a stronger arousing effect on participants' bodies than MICE.
The results of 10 studies that examined both affective responses and physical activity enjoyment during and after exercise indicate that positive affective responses generally enhance the physical enjoyment of activities. When individuals experience pleasure or satisfaction during exercise, they are more likely to report high levels of enjoyment. Table 9 illustrates the relationship between affective responses and enjoyment. The findings of these 10 studies show a consistent pattern, with FS scores being positively correlated with PACES scores under both HIIE and MICE exercise conditions. Positive affective responses during exercise contribute to more enjoyable experiences post-exercise.Table 9Comparing affective and enjoyment.Table 9StudyOutcomeExercise conditionHIIECE(Martinez et al., 2015)^53^FS3.7 ± 1.23.6 ± 1.43.1 ± 1.83.0 ± 1.4PACES91 ± 1498 ± 1583 ± 2482 ± 19(Ayob et al., 2023a)^39^FSP-HIIE < S-HIIE–PACES(111 ± 9 [s1]) – (117 ± 6 [s8]) – (117 ± 7 [s15])(112 ± 12 [s1]) – (116 ± 6 [s8]) – (120 ± 8 [s15])(Ram et al., 2022)^42^FS(2.3 ± 0.9) – (2.69 ± 0.9)(1.75 ± 1.2) – (2.09 ± 1.1)PACES4.4 ± 0.44.3 ± 0.3(Li et al., 2022)^43^FS1.5 ± 1.40.2 ± 1.2–PACES96.8 ± 13.992.5 ± 11.4(Decker & Ekkekakis, 2017)^55^FS−0.04 ± 1.941.13 ± 1.34PACES82.75 ± 21.7690.79 ± 22.60(Tsirigkakis et al., 2022)^46^FSHIIT10 > HIIT60–PACESHIIT10 > HIIT60(Farias-Junior et al., 2019)^47^FS−3.1 ± 1.80.8 ± 1.8PACES106.0 ± 16.596 ± 14.5(Ayob et al., 2023b)^51^FS1 ± 0.82.58 ± 1.5–PACES117 ± 7120 ± 8(Halvorson, 2016)^52^FS3.25 ± 1.353.75 ± 0.93.4 ± 1.05PACES5.2 ± 0.75.65 ± 0.64.85 ± 0.9(Martinez, 2013)^56^FS3.6 ± 1.43.9 ± 0.83.4 ± 1.53.1 ± 1.4PACES91 ± 17101 ± 1484 ± 2481 ± 22Notes. Abbreviations: FS: Feeling scale; PACES: Physical activity enjoyment scale; P-HIIE: Prescribed HIIE; S-HIIE: Self-paced HIIE; HIIT10: 48 × 10 s at 100% of PPO with 15 s of recovery; HIIT60: 8 × 60 s at 100% PPO with 90 s of recovery.
The figures presented report the frequencies of “high,” “low” and “unclear” bias risks across all studies included in this systematic review. Fig. 2 summarizes the overall bias risks for all studies, while Fig. 3 illustrates the individual bias risks for each selected study. The quality of reporting for most bias risk categories was insufficient to make definitive judgments. This issue is particularly evident in the categories of allocation concealment, blinding methods and selective reporting.Fig. 2Summary of risk of bias of selected studies.Fig. 2Fig. 3Individual risk of bias of selected studies.Fig. 3
The assessment of the quality of evidence for each outcome indicator is included in this systematic review. The results show that the FS Score (HIIE vs MICE), PACES Score (HIIE vs MICE), PACES Score (Lv-HIIE vs HIIE), EES Score (HIIE vs MICE), EES Score (Lv-HIIE vs HIIE), FAS Score (HIIE vs MICE), and the correlation between FS and PACES scores (All interventions) are all outcome indicators of very low-quality evidence, the FS Score for Lv-HIIE vs HIIE is low quality evidence. See Table 10.Table 10GRADE for quality of evidence profile.Table 10OutcomeInterventionStudies(participants)Risk of biasInconsistencyIndirectnessImprecisionPublication biasOverall certainty of evidenceFS ScoreHIIE vs MICE8 (168)not seriousserious riskserious riskserious risknot seriousVery LowFS ScoreLv-HIIEvs HIIE6 (157)serious risknot seriousnot seriousserious risknot seriousLowPACES ScoreHIIE vs MICE11 (258)serious riskserious riskserious riskserious risknot seriousVery LowPACES ScoreLv-HIIEvs HIIE6 (157)serious riskserious risknot seriousserious risknot seriousVery LowEES ScoreHIIE vs MICE3 (48)not seriousserious risknot seriousvery serious risknot seriousVery LowEES ScoreLv-HIIEvs HIIE3 (76)not seriousserious risknot seriousvery serious risknot seriousVery LowFAS ScoreHIIE vs MICE2 (50)serious riskserious risknot seriousvery serious risknot seriousVery LowCorrelation between FS and PACES ScoresAll Interventions10 (241)serious riskserious risknot seriousserious risknot seriousVery LowNotes. Abbreviations: FS: Feeling scale; PACES: Physical activity enjoyment scale; EES: Exercise enjoyment scale; FAS: Felt arousal scale; Lv-HIIE: Low-volume high intensity interval exercise.
The benefits of HIIE for physical health are well-established, especially for adults living with excessive weight or obesity. However, to fully understand the potential of exercise to promote health, it is important to consider the affective responses to HIIE in these populations. Previous findings generally suggest that traditional HIIE may lead to negative exercise experiences, which could reduce motivation for future physical activity. As a result, Lv-HIIE may be more acceptable and sustainable for adults with excess body weight or adiposity. The purpose of this systematic review was to examine changes in affective responses to Lv-HIIE in adults living with excessive weight or obesity. A total of 20 studies were included in the review. The findings provide specific indicators of the affective responses of adults with excess body weight or obesity to both interval and continuous exercise. This review is the first to report on changes in affective responses to low-volume high-intensity intervals in individuals with excess body weight or obesity. Overall, we found that changes in affective responses to exercise in this population were directly linked to exercise intensity.
The findings from this review highlight the growing interest in the field, with an increasing number of researchers exploring and experimenting within this area. All studies were conducted in laboratory settings, offering a controlled environment for regulating exercise intensity, although variations in training intensities and interval durations were observed. To enhance the applicability and generalisability of HIIE, future research could consider incorporating outdoor environmental factors into their analyses.
The results of the studies indicate that HIIE generally elicits a significantly better affective state compared to MICE.^42^^,^^44^^,^^53^^,^^56^ Positive affect during exercise is likely to foster behavioural maintenance, as these positive experiences provide immediate affective rewards, thereby reducing the likelihood of exercise discontinuation. However, for some participants with excess body weight or obesity, long-duration, high-intensity HIIE interventions can evoke negative affective responses,^47^^,^^55^ which may decrease participation. This negative response is especially pronounced at the start of exercise; when individuals feel overwhelmed by the intensity, they may associate HIIE with unpleasant experiences, leading to a decline in exercise frequency or cessation altogether.^48^ When comparing traditional HIIE to Lv-HIIE for participants living with excessive weight or obesity, the results consistently show that interventions with the same intensity, but a shorter duration tend to produce more favourable affective responses.^36^^,^^43^ Similarly, lower exercise intensities over the same duration can also result in positive affective experiences.^39^^,^^51^ Overall, HIIE, compared to MICE, tends to evoke more positive affective responses in adults with excess body weight or obesity, and among the different HIIE modalities, Lv-HIIE is more readily accepted by participants than traditional HIIE.
In adults with excess body weight or obesity, enjoyment of physical activities plays a significant role in their adherence to fitness and weight loss programmes. The majority of participants in several studies (n = 7/12) reported better physical enjoyment following HIIE compared to MICE,^38^^,^^43^^,^^47^^,^^50^^,^^52^^,^^53^^,^^56^ suggesting that adults with excess body weight or obesity may prefer HIIE as a time-efficient and more enjoyable exercise modality. In three studies, participants’ enjoyment scores were similar after both HIIE and MICE,^36^^,^^42^^,^^49^ even though MICE typically involved longer training durations. Only one study reported greater physical enjoyment following MICE compared to HIIE,^55^ which was attributed to the specific design of the HIIE protocol in that study, where the intervention and interval intensities were consistently high. This made the HIIE less acceptable to participants living with excessive weight or obesity, resulting in lower enjoyment post-exercise. Research on different HIIE modalities indicates that neither lower intensities nor shorter intervals necessarily lead to optimal physical enjoyment.^52^^,^^53^^,^^56^ However, moderate-intensity HIIE is associated with the highest levels of physical enjoyment. In contrast, longer intervention durations per cycle tend to result in the worst enjoyment. Overall, the physical enjoyment of HIIE is greater in adults living with excess body weight or obesity compared to MICE. When selecting HIIE modalities, there is a preference for moderate-intensity interventions. It is crucial to identify enjoyable and suitable exercise forms to effectively engage these populations in physical activities. Lv-HIIE, in particular, can help maintain their interest in exercise while preventing overuse injuries.
Our results indicate a complex interplay between affective responses and enjoyment responses. It was found that during both HIIE and MICE, affective valence during exercise influences overall enjoyment, and both factors contribute to post-exercise enjoyment in participants with excess body weight or adiposity. The relationship between affective responses and enjoyment is relatively direct, with positive affective states often leading to higher levels of enjoyment.^46^ Conversely, negative affective responses can diminish the enjoyment of the activity,^55^ potentially reducing an individual's willingness to engage in similar activities in the future. Overall, appropriate intervention and recovery times are crucial for eliciting positive affective responses in adults living with excess body weight or obesity during exercise. Moderate-intensity exercise interventions tend to enhance post-exercise enjoyment by providing a sense of achievement and satisfaction. In contrast, excessively high intensity can lead to negative affective experiences, thus reducing overall enjoyment.
In the GRADE assessment, several factors contributed to the downgrading of the quality of evidence. First, the limited number of participants highlights the need for additional high-quality randomized controlled trials (RCT) to strengthen the evidence base. Second, the effects of the interventions remain uncertain, with only the FS score for LV-HIIE versus HIIE considered of low quality but marginally acceptable. This points to the need for cautious interpretation of these specific results. Third, inconsistencies across interventions have led to decreased credibility of the outcomes. Despite all protocols involving high-intensity interval exercise, the considerable heterogeneity in internal interventions suggests varying impacts on the outcomes. This variation underscores the complexity of designing uniform HIIE protocols. Future studies should make efforts to address these inconsistencies and explore the reasons behind the heterogeneity to better understand how different HIIE protocols may influence the studied outcomes. This is also a key consideration for future RCTs in this field.
This systematic review is limited by the small number of studies, which are from journals of varying quality, potentially influencing the breadth and depth of the findings. Additionally, the inclusion of only English-language papers may introduce a risk of publication bias. Most studies have focused primarily on short-term (12-week) affective changes, leaving a gap in understanding of the long-term effects of exercise on affective responses. Furthermore, the participants in these studies were recruited from specific geographic regions, and their dietary habits may have influenced the outcomes, introducing potential confounding. The methods for reporting affective responses are inconsistent across studies, with variations in the scales used and the timing of assessments, which complicates the interpretation of results and adds complexity to the comparative analysis.
This review primarily focuses on short-term affective changes, suggesting that future research should examine the sustained impact of HIIE on affective responses in adults with excess body weight or adiposity over the long term, including effects that persist for months or even years after exercise. Given the potential influence of factors such as age and dietary habits, future studies could explore how these variables affect emotional changes and address the specific affective needs of distinct groups, such as college students or office workers, after exercise. The studies included in this review involved up to 60 participants; to enhance the generalisability of the findings and reduce potential errors, future research could involve larger sample sizes. Additionally, there is variation in the affective assessment scales used across studies; standardising these scales and methods would facilitate more accurate comparisons. Future research might also investigate the physiological and psychological mechanisms underlying the effects of HIIE on affective responses, including the role of hormonal changes in shaping emotional outcomes.
This is the first systematic review to examine affective changes in adults with excess body weight or obesity during Lv-HIIE, thus contributing valuable insights into exercise options for this population. The findings suggest that, in general, most adults with excess weight or obesity experience more positive affective responses during HIIE compared to MICE. In studies comparing traditional HIIE with Lv-HIIE, participants consistently report significantly better affective responses during Lv-HIIE. While participants may initially experience greater exertion and discomfort during HIIE than MICE, they often report a significant improvement in physical enjoyment over time following HIIE. In contrast, a few studies indicate that participants experience greater enjoyment after MICE than HIIE, possibly due to excessively high exercise intensity or other factors related to HIIE. These seemingly contradictory findings emphasize the need for further research to clarify the relationships between affective responses and enjoyment. Overall, Lv-HIIE has proven to be an effective and sustainable exercise strategy that increases the likelihood of long-term physical activity adherence in adults living with excessive weight or obesity, benefiting both affective and physical health. As such, promoting Lv-HIIE as a sustainable health intervention for adults with excess body weight or obesity is highly beneficial.
Ruohan Zhang: Writing – original draft, Methodology, Formal analysis, Data curation, Conceptualization. Adam A. Malik: Writing – review & editing, Supervision, Funding acquisition. Hairul A. Hashim: Writing – review & editing, Supervision, Project administration, Funding acquisition.
(1) Informed consent from each participant was collected; (2) the study was reviewed and received approval to implement by the Universiti Sains Malaysia Human Research Ethics Committee (USM/JEPeM/22080549); and (3) the study was implemented in accordance with the Declaration of Helsinki.
The data is available upon request from the corresponding author.
This work was supported by the Ministry of Higher Education of Malaysia through the Fundamental ResearchGrantScheme *(*FRGS/1/2022/SKK06/USM/03/5).
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.