When Studying Affective Responses to Exercise, the Definition of "Intensity" Must Reference Homeostatic Perturbations: A Retort to Vollaard et al.

In articles on the methodology of studies investigating affective and enjoyment responses to high-intensity interval training, we noted that, occasionally, exercise conditions described as involving "high" intensity exhibited heart rates that were only as high as, or even lower than, heart rates recorded during comparator conditions described as being of "moderate" intensity. Drs. Vollaard, Metcalfe, Kinghorn, Jung, and Little suggest instead that exercise intensity in high-intensity interval-training studies can be defined in terms of percentages of peak workload. Although we maintain that defining exercise intensity in terms of percentages of maximal heart rate is a suboptimal way to quantify the degree of homeostatic perturbations in response to exercise, we are unconvinced that definitions of intensity relying solely on workload are appropriate for studies investigating affective and enjoyment responses to exercise. The reason is that affect is theorized to have evolved to relay information about homeostatic perturbations to consciousness.

A Methodological Checklist for Studies of Pleasure and Enjoyment Responses to High-Intensity Interval Training: Part I. Participants and Measures.

For decades, the exercise psychology research literature echoed the conclusion that exercise makes most people feel better, with no clear evidence that this "feel-better effect" is moderated by intensity. An overhaul of the methodological approach subsequently showed that high-intensity exercise is experienced as unpleasant, and the "feel-better effect," although possible, is conditional and therefore not as robust or prevalent as initially thought. Recently, several studies investigating high-intensity interval training (HIIT) have concluded that HIIT is pleasant and enjoyable, despite the high intensity. Considering that HIIT is emerging as an option in physical activity recommendations and exercise prescription guidelines, in part due to these claims, a methodological checklist is presented to aid researchers, peer reviewers, editors, and other readers in critically appraising studies examining the effects of HIIT on affect and enjoyment. This first part addresses the characteristics and number of participants, as well as the selection of measures of affect and enjoyment.

A Methodological Checklist for Studies of Pleasure and Enjoyment Responses to High-Intensity Interval Training: Part II. Intensity, Timing of Assessments, Data Modeling, and Interpretation.

Recent studies have concluded that high-intensity interval training should be seen as a "viable alternative" to, and may be more enjoyable than, moderate-intensity continuous exercise. If true, these claims have the potential to revolutionize the science and practice of exercise, establishing high-intensity interval training as not only a physiologically effective exercise modality but also a potentially sustainable one. However, these claims stand in contrast to voluminous evidence according to which high levels of exercise intensity are typically experienced as less pleasant than moderate levels. To help researchers, peer reviewers, editors, and critical readers appreciate possible reasons for the apparently conflicting results, we present a checklist that identifies crucial methodological elements in studies investigating the effects of high-intensity interval training on affect and enjoyment. This second installment covers how "high-intensity" and "moderate-intensity" experimental conditions are defined, the timing of assessments of affect, the modeling of affective responses, and data interpretation.

Affective Responses to Increasing- and Decreasing-Intensity Resistance Training Protocols.

This study compared the effects of an increasing-intensity (UP) and a decreasing-intensity (DOWN) resistance training protocol on affective responses across six training sessions. Novice participants (Mage 43.5 ± 13.7 years) were randomly assigned to UP (n = 18) or DOWN (n = 17) resistance training groups. Linear mixed-effects models showed that the evolution of affective valence within each training session was significantly moderated by the group (b = -0.45, p ≤ .001), with participants in the UP group reporting a decline in pleasure during each session (b = -0.82) and the DOWN group reporting an improvement (b = 0.97; ps < .001). Remembered pleasure was significantly higher in the DOWN group compared to the UP group (b = 0.57, p = .004). These findings indicate that a pattern of decreasing intensity throughout a resistance exercise session can elicit more positive affective responses and retrospective affective evaluations of resistance training.

Contactless differentiation of pleasant and unpleasant valence: Assessment of the acoustic startle eyeblink response with infrared reflectance oculography.

The ability to distinguish between discrete emotions by monitoring autonomic or facial features has been an elusive "holy grail" for fields such as psychophysiology, affective computing, and human-computer interface design. However, cross-validated models are lacking, and contemporary theory suggests that emotions may lack distinct physiological or facial "signatures." Therefore, in this study, we propose a reorientation toward distinguishing between pleasant and unpleasant affective valence. We focus on the acoustic eyeblink response, which exhibits affective modulation but remains underutilized. The movement of the eyelid was monitored in a contactless manner via infrared reflectance oculography at 1 kHz while 36 participants viewed normatively pleasant, neutral, and unpleasant images, and 50-ms bursts of white noise were presented binaurally via headphones. Startle responses while viewing pleasant images exhibited significantly smaller amplitudes than those while viewing unpleasant images, with a large effect size (d = 1.56). The affective modulation of the eyeblink startle response is a robust phenomenon that can be assessed in a contactless manner. As research continues on whether systems based on psychophysiological or facial features can distinguish between discrete emotions, the eyeblink startle response offers a relatively simple way to distinguish between pleasant and unpleasant affective valence.

Dynamics of pleasure-displeasure at the limit of exercise tolerance: conceptualizing the sense of exertional physical fatigue as an affective response.

The search for variables involved in the regulation and termination of exercise performance has led to integrative models that attribute a central role to the brain and utilize an array of psychological terms (e.g. sensation, perception, discomfort, tolerance). We propose that theorizing about exercise regulation would benefit from establishing cross-disciplinary bridges to research fields, such as affective psychology and neuroscience, in which changes along the dimension of pleasure-displeasure are considered the main channel via which homeostatic perturbations enter consciousness and dictate corrective action (slowing down or stopping). We hypothesized that ratings of pleasure-displeasure would respond to the severity of homeostatic perturbation and would be related to time to exhaustion during exercise performed at an unsustainable intensity. In a within-subjects experiment (N=15, 13 men and 2 women, age 23.4±2.2 years; maximal oxygen uptake 46.0±8.0 ml kg-1 min-1), we compared the slope of ratings of pleasure-displeasure (acquired every 1 min) during cycling exercise at a power output 10% above critical power until volitional termination under glycogen-loaded and glycogen-depleted conditions. As hypothesized, ratings of pleasure-displeasure declined more steeply under glycogen depletion (P=0.009, d=0.70) and correlated closely with time to exhaustion under both glycogen-loaded (r=0.85; P<0.001) and glycogen-depleted conditions (r=0.83; P<0.001). We conclude that in exercise, as in other domains, changes in pleasure-displeasure may be the main channel via which homeostatic perturbations enter consciousness. This proposal may have important implications for conceptualizing and identifying the neurobiological mechanisms of the sense of exertional physical fatigue.

Critical Review of Measurement Practices in the Study of Automatic Associations of Sedentary Behavior, Physical Activity, and Exercise.

Studies of automatic associations of sedentary behavior, physical activity, and exercise are proliferating, but the lack of information on the psychometric properties of relevant measures is a potential impediment to progress. The purpose of this review was to critically summarize measurement practices in studies examining automatic associations related to sedentary behavior, physical activity, and exercise. Of 37 studies, 27 (73%) did not include a justification for the measure chosen to assess automatic associations. Additional problems have been noted, including the nonreporting of psychometric information (validity, internal consistency, test-retest reliability) and the lack of standardization of procedures (e.g., number, type of stimuli). The authors emphasize the need to select measures based on conceptual arguments and psychometric evidence and to standardize measurement procedures. To facilitate progress, the review concludes with a proposal for conceptually appropriate validation criteria to be used in future studies.

Mass media representations of the evidence as a possible deterrent to recommending exercise for the treatment of depression: Lessons five years after the extraordinary case of TREAD-UK.

Exercise or physical activity are recommended options within stepped-care treatment models for depression. However, few physicians present these options to patients, in part because of the impression that the supporting evidence is weak or inconsistent. We speculate that the coocurrence of "counter-messaging" and deficient critical appraisal may lead to such impressions. We focus on TREAD-UK (ISRCTN16900744), the largest trial to investigate "whether physical activity can be an effective treatment for depression within primary care". In media statements, researchers declared that exercise was ineffective in lowering depression. We examined (a) the results of the trial, critiques, and rejoinders, (b) the impact on internet searches, and (c) whether TREAD-UK was critically appraised, as reflected in citing articles. We show that the results of TREAD-UK were misrepresented. The media campaign resulted in a fourfold increase in relevant internet searches. Of articles characterising the results, 57% adopted the interpretation that exercise failed to lower depression, whereas only 17% were critiques. We identify similarities to media portrayals of the OPERA (ISRCTN43769277), DEMO (NCT00103415), and DEMO-II trials (NCT00695552). We note a disconcerting trend of media campaigns that misrepresent the effects of exercise on depression and call for increased scrutiny in peer reviewing both pre- and post-publication.

A critical review of exercise as a treatment for clinically depressed adults: time to get pragmatic.

OBJECTIVE: Although considerable evidence supports the efficacy of exercise as an antidepressant treatment, critical reviews informing routine practice and future research directions are scarce. METHODS: We critically reviewed exercise studies for clinically depressed adults, focussing on the PICOS criteria referred to participants, interventions, comparisons, outcomes, and study designs. RESULTS: Most studies have not screened their samples for symptom heterogeneity. Also, they have employed heterogeneous exercise interventions and control groups that may lead to an underestimation of the benefits of exercise. In addition, pragmatic trials allowing scalable replication and implementation in routine practice are scarce. Future studies, can consider the research domain criteria as a diagnostic framework, and conduct moderator analyses to identify depressed subgroups with symptomatology and biopsychosocial characteristics associated with differential responses to exercise interventions. The search for biomarkers of the antidepressant responses to exercise should be prioritised. Further, non-physically active comparison groups should be used to minimise treatment cross-overs and thus the underestimation of the effects of exercise interventions. Finally, the use of outcome measures that maintain their validity at low and moderate levels of symptom severity and the development of trials with a pragmatic design are essential. CONCLUSION: The current evidence base is fraught with methodological considerations that need to be taken into account in order to increase further our understanding on the impact of exercise as medicine in depression. Future research should include moderator analyses, incorporate biomarker assays, use appropriate control and comparison groups, assess outcomes with psychometrically sensitive measures, and prioritise pragmatic trials towards transition to routine practice.

Can You Have Your Vigorous Exercise and Enjoy It Too? Ramping Intensity Down Increases Postexercise, Remembered, and Forecasted Pleasure.

There is a paucity of methods for improving the affective experience of exercise. We tested a novel method based on discoveries about the relation between exercise intensity and pleasure, and lessons from behavioral economics. We examined the effect of reversing the slope of pleasure during exercise from negative to positive on pleasure and enjoyment, remembered pleasure, and forecasted pleasure. Forty-six adults were randomly assigned to a 15-min bout of recumbent cycling of either increasing intensity (0-120% of watts corresponding to the ventilatory threshold) or decreasing intensity (120-0%). Ramping intensity down, thereby eliciting a positive slope of pleasure during exercise, improved postexercise pleasure and enjoyment, remembered pleasure, and forecasted pleasure. The slope of pleasure accounted for 35-46% of the variance in remembered and forecasted pleasure from 15 min to 7 days postexercise. Ramping intensity down makes it possible to combine exposure to vigorous and moderate intensities with a pleasant affective experience.

Knowledge of exercise prescription guidelines among certified exercise professionals.

This survey assessed the knowledge of the "Guidance for prescribing exercise" issued by the American College of Sports Medicine (ACSM) in 2011 among certified exercise professionals. A sample of 1,808 certified exercise professionals (66.70% women, mean (± SD) age = 38.28 ± 12.56 years) responded to electronic invitations. The 11-question online questionnaire assessed knowledge of the recommended frequency, duration, and intensity ranges in terms of heart rate, metabolic equivalents, and ratings of perceived exertion. Respondents had 7.45 ± 8.07 years of work experience and represented all 50 U.S. states. On average, participants answered 42.87 ± 1.69% of the questions correctly. Gender, age, and years of professional experience were not associated with overall knowledge of the guidelines. Likewise, having 1, 2, or 3+ certifications made no difference in overall knowledge. However, there were significant differences between levels of education (F = 7.12, p < 0.001), from 38.72 ± 1.62% for "some college" to 47.01 ± 1.71% for "doctorate." There were also significant differences by primary job role (F = 3.45, p < 0.001) but no category exceeded 49% (e.g., personal trainers: 40.59 ± 1.66%; clinical exercise physiologists: 44.18 ± 1.70%). The respondents rated their knowledge of the exercise prescription guidelines as 7.01 ± 1.69 of 10 but rated the level of knowledge necessary to practice safely and effectively as 8.32 ± 1.64 (t = 28.60, p < 0.001). This survey, the first at this scale to investigate the knowledge of exercise prescription guidelines among certified exercise professionals, showed that there is room for improvement, considering that the average score was below 50%.

Associations between attention, affect and cardiac activity in a single yoga session for female cancer survivors: an enactive neurophenomenology-based approach.

Yoga practice is reported to lead to improvements in quality of life, psychological functioning, and symptom indices in cancer survivors. Importantly, meditative states experienced within yoga practice are correlated to neurophysiological systems that moderate both focus of attention and affective valence. The current study used a mixed methods approach based in neurophenomenology to investigate associations between attention, affect, and cardiac activity during a single yoga session for female cancer survivors. Yoga practice was associated with a linear increase in associative attention and positive affective valence, while shifts in cardiac activity were related to the intensity of each yoga sequence. Changes in attention and affect were predicted by concurrently assessed cardiac activity. Awareness of breathing, physical movement, and increased relaxation were reported by participants as potential mechanisms for yoga's salutary effects. While yoga practice shares commonalities with exercise and relaxation training, yoga may serve primarily as a promising meditative attention-affect regulation training methodology.

Role of self-reported individual differences in preference for and tolerance of exercise intensity in fitness testing performance.

Performance in fitness tests could depend on factors beyond the bioenergetic and skeletomuscular systems, such as individual differences in preference for and tolerance of different levels of exercise-induced somatosensory stimulation. Although such individual-difference variables could play a role in exercise testing and prescription, they have been understudied. The purpose of these studies was to examine the relationships of self-reported preference for and tolerance of exercise intensity with performance in fitness tests. Participants in study I were 516 men and women volunteers from a campus community, and participants in study II were 42 men recruit firefighters undergoing a 6-week training program. Both the Preference and Tolerance scores exhibited significant relationships with performance in several fitness tests and with body composition and physical activity participation. Preference and Tolerance did not change after the training program in study II, despite improvements in objective and perceived fitness, supporting their conceptualization as dispositional traits. Preference and Tolerance scores could be useful not only in ameliorating the current understanding of the determinants of physical performance, but also in personalizing exercise prescriptions and, thus, delivering exercise experiences that are more pleasant, tolerable, and sustainable.

Can high-intensity exercise be more pleasant?: attentional dissociation using music and video.

Theories suggest that external stimuli (e.g., auditory and visual) may be rendered ineffective in modulating attention when exercise intensity is high. We examined the effects of music and parkland video footage on psychological measures during and after stationary cycling at two intensities: 10% of maximal capacity below ventilatory threshold and 5% above. Participants (N = 34) were exposed to four conditions at each intensity: music only, video only, music and video, and control. Analyses revealed main effects of condition and exercise intensity for affective valence and perceived activation (p < .001), state attention (p < .05), and exercise enjoyment (p < .001). The music-only and music-and-video conditions led to the highest valence and enjoyment scores during and after exercise regardless of intensity. Findings indicate that attentional manipulations can exert a salient influence on affect and enjoyment even at intensities slightly above ventilatory threshold.

Extraordinary claims in the literature on high-intensity interval training (HIIT): IV. Is HIIT associated with higher long-term exercise adherence?

Nonadherence to and dropout from regular exercise and physical activity are important reasons why the field of exercise science has yet to fulfill its promise of improving public health on a global scale. Researchers have claimed that High-Intensity Interval Training (HIIT) is a feasible and sustainable exercise modality that may result in higher long-term adherence than moderate-intensity continuous exercise. If true, this would be a breakthrough discovery that could unlock the potential of exercise as a health-promoting intervention. We performed a systematic search of the literature and identified eight trials comparing HIIT to moderate-intensity continuous exercise, all of which involved follow-up periods of at least 12 months (i.e., SWIFT, Small Steps for Big Changes, SAINTEX-CAD, SMARTEX-HF, Generation 100, FITR, OptimEx-Clin, HITTS). Findings from these trials demonstrate that, while unsupervised, individuals initially assigned to HIIT tend to exercise at lower-than-prescribed intensities and HIIT groups demonstrate no advantage in long-term adherence.

Baseless Claims and Pseudoscience in Health and Wellness: A Call to Action for the Sports, Exercise, and Nutrition-Science Community.

The global health and wellness industry has an estimated value of US$4 trillion. Profits derive from heath club memberships, exercise classes, diets, supplements, alternative 'therapies', and thousands of other products and services that are purported to improve health, recovery, and/or sports performance. The industry has expanded at an alarming rate, far outstripping the capacity of federal bodies to regulate the market and protect consumer interests. As a result, many products are sold on baseless or exaggerated claims, feigned scientific legitimacy, and questionable evidence of safety and efficacy. This article is a consciousness raiser. Herein, the implications of the mismatch between extraordinary health and performance claims and the unextraordinary scientific evidence are discussed. Specifically, we explore how pseudoscience and so-called 'quick fix' interventions undermine initiatives aimed at evoking long-term behavior change, impede the ongoing pursuit of sports performance, and lead to serious downstream consequences for clinical practice. Moreover, pseudoscience in health and wellness, if left unchecked and unchallenged, may have profound implications for the reputation of exercise science as a discipline. This is a call to action to unify exercise scientists around the world to more proactively challenge baseless claims and pseudoscience in the commercial health and wellness industry. Furthermore, we must shoulder the burden of ensuring that the next generation of exercise scientists are sufficiently skilled to distinguish science from pseudoscience, and information from mis- and disinformation. Better population health, sports performance, and the very reputation of the discipline may depend on it.

Extraordinary Claims in the Literature on High-Intensity Interval Training (HIIT): I. Bonafide Scientific Revolution or a Looming Crisis of Replication and Credibility?

The literature on high-intensity interval training (HIIT) contains claims that, if true, could revolutionize the science and practice of exercise. This critical analysis examines two varieties of claims: (i) HIIT is effective in improving various indices of fitness and health, and (ii) HIIT is as effective as more time-consuming moderate-intensity continuous exercise. Using data from two recent systematic reviews as working examples, we show that studies in both categories exhibit considerable weaknesses when judged through the prism of fundamental statistical principles. Predominantly, small-to-medium effects are investigated in severely underpowered studies, thus greatly increasing the risk of both type I and type II errors of statistical inference. Studies in the first category combine the volatility of estimates associated with small samples with numerous dependent variables analyzed without consideration of the inflation of the type I error rate. Studies in the second category inappropriately use the p > 0.05 criterion from small studies to support claims of 'similar' or 'comparable' effects. It is concluded that the situation in the HIIT literature is reminiscent of the research climate that led to the replication crisis in psychology. As in psychology, this could be an opportunity to reform statistical practices in exercise science.

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

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

Exploring the impact of individualized pleasure-oriented exercise sessions in a health club setting: Protocol for a randomized controlled trial.

Research on the relationship between exercise-induced affect and exercise or physical activity behavior has gained momentum in recent years, yielding several observational and longitudinal studies. However, experimental tests demonstrating a causal role of affective responses on exercise adherence are lacking. Given the need to devise exercise prescriptions that can facilitate adherence and promote regular physical activity, a Randomized Controlled Trial targeting individual pleasurable responses in a health-club setting will be conducted. The experimental protocol will compare two individualized evaluation, prescription, and supervision methods, adjusted for intensity, with the aim to explore their impact on behavioral, affective, and motivational outcomes. The planned study will be a pragmatic randomized, single-blinded, controlled superiority trial with two parallel groups and an allocation ratio of 1:1. Apparently healthy volunteer participants (N = 46) between 18 and 45 years old, who are not regularly active, will be randomly allocated to a control or experimental group. The control group will follow a general American College of Sports Medicine exercise prescription; the experimental group will follow the same prescription but with enhancements aimed at promoting pleasure: (1) individualization based on individual differences in preference for and tolerance of exercise intensity; (2) self-regulation of intensity; and (3) repeated assessments of core affect. The primary outcome will be post-intervention exercise-session attendance. Affective and motivational variables will be examined as secondary outcomes. The results are expected to advance exercise prescriptions by promoting affective regulation, thus helping to improve exercise adherence and related outcomes. TRIAL REGISTRATION: ClinicalTrials.gov; ID: NCT05416593.

Affective responses to stretching exercises: Exploring the timing of assessments.

Affective responses during exercise have been identified as a predictor of exercise adherence. However, research has been mostly limited to aerobic and resistance exercise. Considering that stretching activities are also an important component of physical fitness, this quasi-experimental study was designed to: 1) compare affective responses during and immediately after stretching exercises in apparently healthy adults, and 2) assess the consistency and repeatability of affect ratings obtained one week apart. For this purpose, we analyzed the Feeling Scale (FS) and Felt Arousal Scale (FAS) ratings using Time (during and after stretching) x Intensity (light, moderate, vigorous) x Stretched Muscle Group (quadriceps, hamstrings, glutes, latissimus dorsi, triceps) with repeated measures analysis of variance (ANCOVA) in 34 participants (21 males; aged 32.8 ± 8.6 years). The repeatability of FS and FAS ratings was assessed using two-way random-effects models, Intraclass Correlation Coefficients (ICC), and Bland-Altman plots. FS scores were higher following the stretching exercises, whereas FAS scores were lower, particularly in the vigorous intensity. In general, the inter-day repeatability for FS and FAS measurements was good across muscle groups. ICC tended to be higher at vigorous intensities. Ratings of core affect can be collected during static passive stretches using the FAS and FAS in ecologically valid settings. These results suggest that an adequate assessment of core affective responses to stretching activities should be performed during the exercises.