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.

Perceived exertion is not a substitute for fatiguability in spinal muscular atrophy.

INTRODUCTION/AIMS: Fatiguability and perceived fatigue are common unrelated symptoms in ambulatory individuals with spinal muscular atrophy (SMA). Ratings of perceived exertion (RPE) measures the sense of effort during an activity and has been used as a proxy for fatigue. Relationships between perceived fatigue, fatiguability, and RPE have been described in healthy populations, but the relationship in SMA has not been examined. METHODS: Eighteen ambulatory individuals with SMA and 16 age-matched controls (age, 13 to 57 years; 26 [76.5%] males) performed the 6-minute walk test (6MWT) and cardiopulmonary exercise tolerance test (CPET) and completed the International Physical Activity Questionnaire---short form (IPAQ). RPE was collected during the CPET and 6MWT. Fatiguability was measured during the 6MWT. Physical activity (PA) volume was calculated using the IPAQ. Wilcoxon rank-sum tests were used to compare groups. Spearman correlation coefficients evaluated associations between variables. SMA subgroups were predetermined using 6MWT distances of over or under 300 meters. RESULTS: There were no significant associations between fatiguability and RPE or PA in SMA (P > .05). PA was strongly associated with 6MWT RPE (r = 0.71) in SMA individuals who walked fewer than 300 meters (n = 7). There were no significant associations between any variables in controls (P > .05). DISCUSSION: RPE is not associated with fatiguability in SMA. The possible association of PA and RPE may reflect the increased intensity of the 6MWT in weaker patients. RPE represents a sense of effort during exercise and should not be used as a substitute for fatiguability but may be a measure of patient experience during exercise.

Diminished muscle oxygen uptake and fatigue in spinal muscular atrophy.

OBJECTIVE: To estimate muscle oxygen uptake and quantify fatigue during exercise in ambulatory individuals with spinal muscular atrophy (SMA) and healthy controls. METHODS: Peak aerobic capacity (VO2peak ) and workload (Wpeak ) were measured by cardiopulmonary exercise test (CPET) in 19 ambulatory SMA patients and 16 healthy controls. Submaximal exercise (SME) at 40% Wpeak was performed for 10 minutes. Change in vastus lateralis deoxygenated hemoglobin, measured by near-infrared spectroscopy, determined muscle oxygen uptake (ΔHHb) at rest and during CPET and SME. Dual energy X-ray absorptiometry assessed fat-free mass (FFM%). Fatigue was determined by percent change in workload or distance in the first compared to the last minute of SME (FatigueSME ) and six-minute walk test (Fatigue6MWT ), respectively. RESULTS: ΔHHb-PEAK, ΔHHb-SME, VO2peak , Wpeak , FFM%, and 6MWT distance were lower (P < 0.001), and Fatigue6MWT and FatigueSME were higher (P < 0.001) in SMA compared to controls. ΔHHb-PEAK correlated with FFM% (r = 0.50) and VO2peak (r = 0.41) only in controls. Only in SMA, Fatigue6MWT was inversely correlated with Wpeak (r = -0.69), and FatigueSME was inversely correlated with FFM% (r = -0.55) and VO2peak (r = -0.69). INTERPRETATION: This study provides further support for muscle mitochondrial dysfunction in SMA patients. During exercise, we observed diminished muscle oxygen uptake but no correlation with aerobic capacity or body composition. We also observed increased fatigue which correlated with decreased aerobic capacity, workload, and body composition. Understanding the mechanisms underlying diminished muscle oxygen uptake and increased fatigue during exercise in SMA may identify additional therapeutic targets that rescue symptomatic patients and mitigate their residual disease burden.

Patterns of Sedentary Behavior in the First Month After Acute Coronary Syndrome.

Background Sedentary behavior is a key contributor to cardiovascular disease. Few data exist on the sedentary behavior patterns of patients with acute coronary syndrome. Methods and Results We characterized patterns of sedentary time and their correlates in 149 patients with acute coronary syndrome over the first month postdischarge, a critical period when lifestyle behaviors are formed. Sedentary time was measured by accelerometry for 28 days postdischarge. Group-based modeling at the day level was used to characterize sedentary patterns. Participants spent a mean of 9.7±2.0 hours per day sedentary during the 28 days postdischarge, with significant decreases in sedentary time observed in each consecutive week (P<0.01 for all). Three distinct sedentary patterns were identified: high (20.6% of participants), moderate (47.9%), and low (31.5%). The high and moderate sedentary groups spent a mean of 12.6±0.8 and 10.0±0.7 hours per day sedentary, respectively, and had only minimal decreases in their sedentary time (<3 minutes per day) over the 28 days. The low sedentary group spent a mean of 7.3±0.8 hours per day sedentary, with a rapid decrease in sedentary time (14 minutes per day) observed during the first week postdischarge followed by a relatively smaller decrease (≈5 minutes per day) that persisted until day 21 postdischarge. Non-Hispanic ethnicity, left ventricular ejection fraction <40%, lower physical health-related quality of life, and not having a partner were associated with an increased likelihood of being in the high sedentary group. Conclusions Survivors of acute coronary syndrome accrued high volumes of sedentary time during the first month postdischarge, with most showing little change over time. Interventions targeting reductions in sedentary time among survivors of acute coronary syndrome may be warranted, particularly for those with poor physical health and greater disease severity.

Long-term effects of a stage-based intervention for changing exercise intentions and behavior in older adults.

PURPOSE: We examined the efficacy of an intervention tailored to the individual's stage of change for exercise adoption on exercise stage of change, physical activity, and physical function in community-dwelling older adults. DESIGN AND METHODS: We randomized participants to a print and telephone intervention or a contact comparison group. Through the use of longitudinal analyses we examined the intervention's effectiveness in promoting stage progression, altering decisional balance and the processes of change, increasing self-efficacy and physical activity, and improving physical function among older adults who completed the 24-month study (N = 966). We conducted similar analyses that excluded individuals who were in maintenance at baseline and 24 months. RESULTS: At the end of the study, there were no differences in stage progression, self-efficacy, decisional balance, the processes of change, physical activity, or physical function by intervention assignment. When the analyses excluded those participants (n = 358) who were in the maintenance stage for exercise throughout the intervention, we found that, compared with the comparison group, a greater proportion of individuals who received the exercise intervention progressed in stage by 24 months. Conversely, more individuals in the comparison group remained stable or regressed in stage compared with the intervention group. IMPLICATIONS: Results indicate that a tailored intervention is effective in increasing motivational readiness for exercise in individuals who were in stages of change other than maintenance.

Screening, safety, and adverse events in physical activity interventions: collaborative experiences from the behavior change consortium.

Researchers who conduct physical activity (PA) intervention studies provide an invaluable opportunity to further the prevention science knowledge base for implementing and delivering PA programs. Despite recommendations that screening is important to increase patient safety, the specific screening criteria best suited for different community applications are unknown. To add to the limited knowledge base, we examined the screening procedures and the occurrence of adverse events among more than 5,500 participants from 11 diverse PA interventions participating in a trans-National Institutes of Health (NIH) collaborative known as the Behavior Change Consortium (BCC). Numerous adverse events occur in sedentary, chronically ill, or older populations, although few are attributed to activity/exercise interventions. No serious study-related adverse events (SRAEs) were reported across different screening practices, interventions, and/or populations. Relatively few minor SRAEs were reported (primarily musculoskeletal injuries), emphasizing the need to be aware of potential musculoskeletal sequelae during exercise interventions. One common characteristic of these studies is that they recommended "start low and go slow" strategies, with moderate intensity PA as the goal behavior. Recommendations to reframe the meaning and use of screening criteria to initiate PA in the community are discussed. Although we were unable to conduct generalizable quantitative analyses from our data, the combined experience of the BCC studies provides a unique opportunity to examine PA-related screening and safety issues across diverse populations, settings, and intervention programs.