Bout duration in high-intensity interval exercise modifies hematologic, metabolic and antioxidant responses.

Objective: This study compared hematologic, metabolic and antioxidant responses between three high-intensity interval exercise (HIIE) trials of different bout duration and a continuous exercise trial (CON), all with equal average intensity, total work, and duration. Methods: Eleven healthy young males performed four trials involving 20 min of cycling, either continuously (49% of power at VO2max, PPO), or intermittently with 48 10-s bouts (HIIE10), 16 30-s bouts (HIIE30) or 8 60-s bouts (HIIE60) at 100% PPO, with a 1:1.5 work-to-recovery ratio at 15% PPO. Venous blood was obtained before, immediately after, and 1 h post-exercise to evaluate hematologic, metabolic and antioxidant responses. Blood lactate concentration was measured in capillary blood during exercise, while urine lactate was measured before and 1 h post-exercise. Results: Post-exercise leukocyte count (mean ± SD; 9.7 ± 2.8 k µL-1), uric acid concentration (0.35 ± 0.10 mmol L-1), glucose concentration (6.56 ± 1.44 mmol L-1), and plasma volume change (-13.5 ± 4.4%) were greater in HIIE60 compared to all other trials (p < 0.05). One-hour post-exercise, lymphocytes decreased below pre-exercise values in all HIIE trials, and uric acid increased in the HIIE60 trial (p < 0.05). Urine lactate concentration 1 h post-exercise increased compared to pre-exercise only in HIIE60 (19-fold, p < 0.001), and this was related with the higher blood lactate concentration during exercise in that trial. Conclusions: These findings highlight the importance of bout duration, given that shorter bouts of HIIE (30 s or 10 s) induce lower blood cell perturbations, metabolic stress, and antioxidant responses compared to the commonly used 1-min bouts, despite equal total work, duration, and work-to-recovery ratio.

Physiological, perceptual and affective responses to high-intensity interval training using two work-matched programs with different bout duration in obese males.

Objectives: This study compared physiological, perceptual, and affective responses to high-intensity interval training (HIIT) between two work-matched programs with different bout durations in obese males. Methods: Sixteen low-to-moderately active obese men completed an eight-week cycling program of supervised HIIT (3 days/week) using either short bouts [48 × 10 s at 100% of peak power output (PPO) with 15 s of recovery (HIIT10)] or long bouts [8 × 60 s at 100% PPO with 90 s of recovery (HIIT60)]. Workload was progressively adjusted, to maintain high intensity (100% PPO), throughout training. Blood lactate (BLa), heart rate (HR), ratings of perceived exertion (RPE), and feeling scale ratings (pleasure/displeasure) were measured in each HIIT session. Results: Average HR decreased in the last 2 weeks of training in both groups by 2.2 ± 1.8% of peak HR (p < 0.001). Training resulted in a reduction in BLa during exercise by 28 ± 19% (p < 0.001) from the 10th min onward only in HIIT10. Similarly, during the last weeks of training, RPE decreased (by 1.0 ± 1.1 units, p < 0.05) and feeling scale ratings were improved only in HIIT10, while RPE remained unchanged and feeling scale ratings deteriorated in HIIT60 (from 3.0 ± 1.1 to 2.1 ± 0.9 units, p < 0.001). No differences in post-exercise enjoyment were found. Conclusion: Both HIIT formats induced similar HR adaptations, but improvement of BLa, perceptual and affective responses occurred only when bout duration was shorter. Our findings suggest that, in low-to-moderately active obese men, HIIT may be more effective in improving metabolic, perceptual, and affective responses when shorter, rather than longer, bouts of exercise are used.

Acute and delayed hormonal and blood cell count responses to high-intensity exercise before and after short-term high-intensity interval training.

The acute and delayed hormonal and blood cell responses to a high-intensity interval training (HIIT) session, were examined before and after a 3-week intervention (9 HIIT sessions of 4-6 × 30 s high-intensity cycling bouts) in eight recreationally active male volunteers (age: 24.3 ± 1.4 y, VO2max: 41.2 ± 3.2 ml/kg/min). Blood samples were collected before and 0.5, 24, 48 h following the first and last training session. Before training, the HIIT session induced acute increases in cortisol, prolactin and TSH concentration, while free-T4 peaked 24 h later (p < 0.001) and testosterone remained unchanged. White blood cell count was increased 0.5 h after exercise (p < 0.001), while lymphocyte percentage decreased 24 h post exercise (p < 0.01). After three weeks of HIIT, cortisol, WBC and lymphocyte responses were decreased by ~42% (p = 0.002), 8.6% (p = 0.032) and 9.6% (p = 0.039), respectively, despite an increase in total work. These findings show that short-term HIIT may induce rapid adaptations of the hypothalamic-pituitary-adrenal axis and may blunt exercise-induced immune responses.

High-intensity Interval Training Frequency: Cardiometabolic Effects and Quality of Life.

The effects of high intensity interval training (HIIT) frequency on cardiometabolic health and quality of life were examined in 35 healthy inactive adults (age: 31.7±2.6 yrs, VO2peak: 32.7±7.4 ml·: kg-1 ·: min-1). Participants were randomly assigned to a control (CON) and two training groups, which performed 10×60-s cycling at ~83% of peak power, two (HIIT-2) or three times per week (HIIT-3) for eight weeks. Compared with CON, both training regimes resulted in similar improvements in VO2peak (HIIT-2: 10.8%, p=0.048, HIIT-3: 13.6%, p=0.017), waist circumference (HIIT-2: -1.4 cm, p=0.048, HIIT-3: -2.4 cm, p=0.028), thigh cross-sectional area (HIIT-2: 11.4 cm2, p=0.001, HIIT-3: 9.3 cm2, p=0.001) and the physical health component of quality of life (HIIT-2: 8.4, p=0.001, HIIT-3: 12.2, p=0.001). However, HIIT-3 conferred additional health-related benefits by reducing total body and trunk fat percentage (p<0.05, compared with CON), total cholesterol and low-density lipoprotein-cholesterol (p<0.02, compared with CON) and by improving the mental component of quality of life (p=0.045, compared with CON). In conclusion, performing HIIT only twice per week is effective in promoting cardiometabolic health-related adaptations and quality of life in inactive adults. However, higher HIIT frequency is required for an effect on fat deposits, cholesterol and mental component of well-being.

Effects of chronic physical exercise on executive functions and episodic memory in clinical and healthy older adult populations: a systematic review and meta-analysis protocol.

BACKGROUND: Executive functions (EFs) and episodic memory are fundamental components of cognition that deteriorate with age and are crucial for independent living. While numerous reviews have explored the effect of exercise on these components in old age, these reviews screened and analyzed selected older adult populations, or specific exercise modes, thus providing only limited answers to the fundamental question on the effect of exercise on cognition in old age. This article describes the protocol for a systematic review and multilevel meta-analytic study aiming at evaluating the effectiveness of different types of chronic exercise in improving and/or maintaining EFs and long-term episodic memory in older adults. METHODS AND ANALYSIS: The study protocol was written in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Several databases will be searched. Randomized controlled trials (RCTs) conducted in older adults aged ≥ 60 years providing any kind of planned, structured, and repetitive exercise interventions, and EFs and/or episodic memory measures as outcomes, published in English in peer-reviewed journals and doctoral dissertations will be included. Two independent reviewers will screen the selected articles, while a third reviewer will resolve possible conflicts. The Cochrane risk-of-bias tool will be used to assess the quality of the studies. Finally, data will be extracted from the selected articles, and the formal method of combining individual data from the selected studies will be applied using a random effect multilevel meta-analysis. The data analysis will be conducted with the metafor package in R. DISCUSSION AND CONCLUSION: This review will synthesize the existing evidence and pinpoint gaps existing in the literature on the effects of exercise on EFs and episodic memory in healthy and unhealthy older adults. Findings from this meta-analysis will help to design effective exercise interventions for older adults to improve and/or maintain EFs and episodic memory. Its results will be useful for many researchers and professionals working with older adults and their families. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42022367111.

Chronic exercise effects on overall depression severity and distinct depressive symptoms in older adults: A protocol of a systematic and meta-analytic review.

INTRODUCTION: There is high evidence that chronic exercise benefits overall depression severity in older adults. However, late-life depression is characterized by considerable heterogeneity in clinical manifestation emphasizing the need for more individualized exercise intervention programs. Therefore, the objective of the proposed review is to investigate the effects of chronic exercise on overall depression severity and on different symptoms of depression in randomized controlled trials (RCTs) including older adults with a mean age of at least 60 years, and by considering the moderating effects of intervention characteristics and individual characteristics. METHODS: This protocol is guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P). We will use the Population-Intervention-Comparator-Outcomes-Study design (PICOS) criteria for study inclusion and will search the following database sources for relevant RCTs: Web of Science, Academic Search Complete, CINAHL, APA Psycinfo, SPORTDiscuss, Cochrane. Two independent reviewers will conduct the study selection, data extraction, and quality assessment. Disagreement will be solved by a third reviewer. Primary outcome will be changes in overall depression severity and secondary outcomes will encompass changes in symptoms of depression as defined by the DSM-5, such as sleep quality, fatigue, anxiety, mood, apathy, changes in weight, information processing speed, and executive functions, from baseline until the end of the intervention and to any available intermediary measurement or follow up. Meta-analysis will be undertaken to synthesize the effects of chronic exercise on primary and secondary outcomes. Subgroup analysis will investigate the moderating effects of intervention characteristics (frequency, intensity, duration, type of exercise, cognitive demand, social interactions, exercise supervision, behavioral change techniques, compliance, study design, dropout-rate, type of control group) and individual characteristics (age, sex, education, functional capacity, global cognition, population) on primary and secondary outcomes. Additionally, we plan to assess quality of evidence and publication bias, and to carry out sensitivity analysis. CONCLUSION: The results of the proposed review are anticipated to have a substantial impact on research and clinical practice. On the one hand, the review's conclusions could form the foundation for developing evidence-based recommendations for individualized exercise programs that alleviate depression in older adults. On the other hand, by revealing research gaps, the review results could encourage the formulation of research questions for further RCTs. PROTOCOL REGISTRATION NUMBER: This protocol has been published in the Prospero repository (PROSPERO 2022 CRD42022361418, available from: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022361418).

Shorter Versus Longer Durations of Rowing-Based Interval Exercise Attenuate the Physiological and Perceptual Response.

Purpose: This study compared physiological and perceptual variables between short and long durations of rowing-based high intensity interval exercise (HIIE). Methods: Fourteen active adults (age = 26.4 ± 7.2 yr) performed incremental rowing exercise to fatigue to measure maximal oxygen uptake (VO2max) and peak power output (PPO). The subsequent 20 min sessions required HIIE (eight 60 s efforts at 85%PPO with 90 s of active recovery at 20%PPO or 24 20 s efforts at 85%PPO with 30 s of active recovery at 20%PPO) or moderate intensity continuous exercise (MICE) at 40%PPO. During exercise, VO2, heart rate (HR), blood lactate concentration (BLa), rating of perceived exertion (RPE), and affective valence were measured. Results: Data show significantly (p < 0.001) higher peak VO2 (84 ± 7 vs. 76 ± 5%VO2peak, d = 0.99), peak HR (94 ± 4%HRpeak vs. 90 ± 4%HRpeak, d = 1.12), BLa (7.0 ± 2.5 mM vs. 4.1 ± 1.0 mM, d = 1.22), end-exercise RPE (12.8 ± 2.0 vs. 11.0 ± 1.7, d = 1.29), and lower affective valence (2.1 ± 1.6 vs. 2.9 ± 1.2, d = 0.61) with long versus short HIIE. Time spent above 85%HRpeak was significantly higher (p < 0.001) in short versus long HIIE (606 ± 259 vs. 448 ± 26 s, d = 0.91). Conclusion: Longer rowing-based intervals elicit greater cardiometabolic and perceptual strain versus shorter efforts, making the latter preferable to optimize perceptual responses to HIIE.

Association of Body Composition with Functional Capacity and Cognitive Function in Older Adults Living in Nursing Homes.

BACKGROUND: Older adults living in nursing homes have an increased risk of adverse outcomes. However, the role of body composition in vital health and quality of life parameters such as functional capacity and cognitive function is less studied in this group of older adults compared to community-dwelling counterparts. OBJECTIVE: The aim of the present study was to examine the association of body composition with functional capacity and cognitive function in nursing home residents. METHODS: Fifty-three older adults (82.8 ± 7.3 years) were enrolled in this study and they underwent body composition evaluation, functional capacity and cognitive function measurements. RESULTS: The results showed a high prevalence of obesity accompanied by functional capacity limitations and cognitive impairment in older adults living in nursing homes. Partial correlations, controlling for age, showed that body fat percentage was positively correlated with sit-to-stand-5 (r = 0.310, p = 0.025) and timed-up-and-go (r = 0.331, p = 0.017), and negatively correlated with handgrip strength test results (r = -0.431, p<0.001), whereas greater lean body mass was associated with better sit-to-stand-5 (r = -0.410, p = 0.003), handgrip strength (r=0.624, p<0.001) and cognitive function performance (r = 0.302, p = 0.037). CONCLUSIONS: These important associations reinforce the need to develop effective healthy lifestyle interventions targeting both lean mass and body fat to combat functional and cognitive decline in nursing home residents.

Exploring the Associations between Functional Capacity, Cognitive Function and Well-Being in Older Adults.

Background: The present study aimed to explore the associations between functional capacity and global cognition, executive function and well-being in older adults. Methods: Ninety-seven older adults (age 80.6 ± 8.2 years) were examined for global cognitive function (Mini-Mental State Examination), executive function (symbol cancellation test), functional capacity (sit-to-stand tests, 6 min walk test, timed up-and-go test and handgrip strength test) and well-being (quality of life, fatigue levels, sleep quality and daily sleepiness). Adjusted partial correlations were computed to examine the associations between variables. Mediation analyses were conducted to evaluate whether functional capacity would mediate the relationships between age and cognitive or executive function. Results: Greater levels of functional capacity were associated with better performance in cognitive and executive function tests (p < 0.05). Mediation analyses revealed that functional capacity partially mediated the effects of age on global cognition and executive function (indirect effect: ß = −0.11, 95% CI = −0.20 to −0.03; ß = 0.34, 95% CI = 0.13 to 0.57, respectively). Increased levels of functional capacity were also associated with higher quality of life (p < 0.05, r = 0.32 to 0.41), lower fatigue levels (p < 0.05, r = 0.23 to 0.37), and better sleep quality (p < 0.05, r = 0.23 to 0.24). Conclusions: Functional capacity can mediate the effects of age on global cognition and executive function in older adults and greater levels of functional capacity are associated with improved quality of life, better sleep quality, and lower fatigue levels.

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

PURPOSE: To compare the metabolic, cardiorespiratory and perceptual responses to three isoenergetic high-intensity interval exercise (HIIE) protocols of different bout duration and an isoenergetic continuous exercise protocol. METHODS: Eleven healthy males (age, 28 ± 6 yr) performed four 20-min cycling trials of equal mean power output 1 wk apart. Participants cycled either continuously (CON) or intermittently with 10 s (HIIE10), 30 s (HIIE30), or 60 s (HIIE60) bouts at intensities corresponding to 49% (CON) or 100% of power at peak oxygen uptake (V̇O2peak). Recovery intervals during the HIIE trials were 15, 45, and 90 s, respectively. RESULTS: Average V̇O2 was similar in the HIIE trials (2.29 ± 0.42, 2.20 ± 0.43, and 2.12 ± 0.45 L·min-1, for HIIE10, HIIE30, and HIIE60, respectively), whereas in CON (2.02 ± 0.38 L·min-1), it was lower than HIIE10 (P = 0.002) and HIIE30 (P = 0.043). Average pulmonary ventilation (VE) was higher in HIIE60 compared with HIIE10, HIIE30, and CON (75.8 ± 21.8 L·min-1 vs 64.1 ± 14.5 L·min-1, 64.1 ± 16.2 L·min-1, and 54.0 ± 12.5 L·min-1, respectively, P < 0.001). The peak values and oscillations of V̇O2 and VE in HIIE60 were higher compared with all other trials (P < 0.001). Blood lactate concentration was higher in HIIE60 compared with HIIE10, HIIE30, and CON from the fifth minute onward, reaching 12.5 ± 3.5, 7.2 ± 2.1, 7.9 ± 2.9, and 4.9 ± 1.6 mmol·L-1, respectively, at the end of exercise (P < 0.001). RPE was higher and affective responses were lower in HIIE60 compared with all other trials toward the end of exercise (P < 0.001). CONCLUSIONS: These findings highlight the importance of bout duration in HIIE, since shorter bouts resulted in attenuated metabolic and cardiorespiratory responses, lower RPE and feelings of displeasure compared with a longer bout, despite equal total work, duration, and work-to-recovery ratio. These results may have implications for the prescription of HIIE in various populations.