Effects of Short-term 3-Day Caloric Restriction on Cardiometabolic Health in Overweight and Obese Individuals

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The Effects of COVID-19 Restrictions on College Students Physical Activity and Mental Health

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EVALUATION OF INDIVIDUAL CARDIOVASCULAR REGULATION ADAPTATIONS FOLLOWING HIGH INTENSITY FUNCTIONAL TRAINING

Aidan Lewis1, Justin DeBlauw1, Derek A. Crawford2, Katie M. Heinrich1, FACSM 1Kansas State University, Manhattan, KS; 2University of Central Missouri, Warrensburg, MO Higher resting heart rate (RHR) is positively associated with higher all-cause mortality. Aerobic exercise training helps lower RHR. High intensity functional training (HIFT) has had similar effects in women, but is unexplored among men. Heart rate variability (HRV) monitoring can assess individual adaptation and allow for more precise HIFT prescription and beneficial cardiovascular adaptations. PURPOSE: To determine effects of HRV-modulated HIFT on RHR and HRV changes. METHODS: Healthy adults (N = 55) were randomly assigned to HIFT (n = 29, age = 24.1 ± 4.1 years, 41.4% men) or HIFT-HRV modulated (n = 26, age = 23.7 ± 4.5, 53.8% men) groups. Both groups completed 11-weeks of daily HRV recordings with a validated smart phone application and 6-weeks of HIFT (5 d·week-1) and were assessed pre and post for changes in RHR, HRV and coefficient of variance (CV) in HRV. Meaningful changes in resting HRV were used to modulate (i.e., reduce) HIFT-HRV participants’ exercise intensity. Linear mixed models were used with the Bonferroni post hoc adjustment to look at RHR, HRV, and CV in HRV. RESULTS: No significant main effects for group, sex, or time were found for change in HRV (ps = .09-.40) or for group or time for changes in the CV in HRV (ps = 0.38-0.75). However, there was a significant main effect for gender on the change in CV in HRV (F= 6.23; mean difference= 1.82 ± 0.73; 95% CI= 0.39, 3.25; p = 0.016) with men significantly greater than women. Main effects for group and sex were not significant for RHR change (ps = 0.060.93). However, there was a significant main effect for time (F= 4.89; mean difference= -3.25 ± 1.47; 95% CI= -6.14, -0.37; p = 0.035) with a reduction in resting HR being observed in both groups. CONCLUSION: HIFT training prescription, modulated by daily HRV, produced similar changes in RHR while producing a greater change in the CV in HRV for men. HRV modulated HIFT resulted in beneficial cardiovascular adaptations which has positive implications for reducing the all-cause mortality rate. ACKNOWLEDGEMENTS: This study was funded by the Mindlin Foundation and the Kansas State University Office of Undergraduate Research and Creative Inquiry

Validity, Reliability, and Application of the Session-RPE Method for Quantifying Training Loads during High Intensity Functional Training

The session rate of perceived exertion method (sRPE) has often been utilized in sports activities in which quantification of external training loads is challenging. The multi-modal, constantly varied nature of high intensity functional training (HIFT) represents a significant hurdle to calculate external work and the sRPE method may provide an elegant solution to this problem. However, no studies have investigated the psychometric properties of sRPE within HIFT interventions. Twenty-five healthy men and women participated in six weeks of HIFT. Rate of perceived exertion and heart rate were assessed within every training session throughout the duration of the intervention. Compared to criterion heart rate-based measures, we observed sRPE method is a valid tool across individual, group, and sex levels. However, poor reliability in participants’ abilities to correctly match rate of perceived exertion with the relative level of physiologic effort (i.e., percentile of maximum heart rate) currently limits the utility of this strategy within HIFT. When applied, the validity and reliability of the sRPE seem to improve over time, and future research should continue to explore the potential of this monitoring strategy within HIFT interventions

The effects of short‐term caloric restriction on cardiometabolic health in overweight/obese men and women: A single‐arm trial

Abstract Overweight and obesity (Ow/Ob) is a risk factor for cardiometabolic disease. Caloric restriction (CR) have been investigated but little is known about the acute effects of CR and often such diets are not standardized. Thus, we aimed to assess the impact of a new standardized 3‐day CR diet (590 kcal/d intake) on cardiometabolic health in weight‐stable Ow/Ob individuals. In a single‐arm design, 15 Ow/Ob men and women were assessed pre‐post a 3‐day standardized CR diet; specifically, body weight/composition (%body fat, visceral fat score (Vfs), blood pressure (BP), and vascular stiffness (VS), resting energy expenditure (REE), substrate utilization (respiratory quotient, RQ), and blood glucose/lipid profile). CR lowered body weight (93.1 ± 15.2 to 90.67 ± 14.4 kg, p  0.05). Blood glucose (86 ± 7 to 84 ± 11 mg/dL, p = 0.33) and lipids (total cholesterol (196 ± 49 to 203 ± 54 mg/dL, p = 0.16) and TC/HDL (4.9 ± 2.4 to 6.1 ± 4.7, p = 0.13)) were unchanged. RQ decreased with CR (0.84 ± 0.01 to 0.76 ± 0.00, p < 0.001, d = 1.9), though REE was unchanged (p = 0.83). The 3‐day CR diet significantly improved fat metabolism, body weight and composition, and vascular stiffness

Are Changes in Physical Work Capacity Induced by High-Intensity Functional Training Related to Changes in Associated Physiologic Measures?

High-Intensity Functional Training (HIFT) is a novel exercise intervention that may test body systems in a balanced and integrated fashion by challenging individuals’ abilities to complete mechanical work. However, research has not previously determined if physical work capacity is unique to traditional physiologic measures of fitness. Twenty-five healthy men and women completed a six-week HIFT intervention with physical work capacity and various physiologic measures of fitness assessed pre- and post-intervention. At baseline, these physiologic measures of fitness (e.g., aerobic capacity) were significantly associated with physical work capacity and this relationship was even stronger at post-intervention assessment. Further, there were significant improvements across these physiologic measures in response to the delivered intervention. However, the change in these physiologic measures failed to predict the change in physical work capacity induced via HIFT. These findings point to the potential utility of HIFT as a unique challenge to individuals’ physiology beyond traditional resistance or aerobic training. Elucidating the translational impact of increasing work capacity via HIFT may be of great interest to health and fitness practitioners ranging from strength/conditioning coaches to physical therapists

High-Intensity Functional Training Guided by Individualized Heart Rate Variability Results in Similar Health and Fitness Improvements as Predetermined Training with Less Effort

Heart rate variability (HRV) may be useful for prescribing high-intensity functional training (HIFT) exercise programs. This study aimed to compare effects of HRV-guided and predetermined HIFT on cardiovascular function, body composition, and performance. Methods: Recreationally-active adults (n = 55) were randomly assigned to predetermined HIFT (n = 29, age = 24.1 &plusmn; 4.1 years) or HRV-guided HIFT (n = 26, age = 23.7 &plusmn; 4.5) groups. Both groups completed 11 weeks of daily HRV recordings, 6 weeks of HIFT (5 d&middot;week-1), and pre- and post-test body composition and fitness assessments. Meaningful changes in resting HRV were used to modulate (i.e., reduce) HRV-guided participants&rsquo; exercise intensity. Linear mixed models were used with Bonferroni post hoc adjustment for analysis. Results: All participants significantly improved resting heart rate, lean mass, fat mass, strength, and work capacity. However, no significant between-groups differences were observed for cardiovascular function, body composition, or fitness changes. The HRV-guided group spent significantly fewer training days at high intensity (mean difference = &minus;13.56 &plusmn; 0.83 days; p &lt; 0.001). Conclusion: HRV-guided HIFT produced similar improvements in cardiovascular function, body composition, and fitness as predetermined HIFT, despite fewer days at high intensity. HRV shows promise for prescribing individualized exercise intensity during HIFT

Muscular Strength, Power, and Endurance Adaptations after Two Different University Fitness Classes

Physical activity (PA) classes help college students add weekly PA, which can help improve health and maintain body weight. Traditional weight training (TWT) can improve strength and aerobic capacity. High-intensity functional training such as CrossFit® (CF) provides time-efficient workouts with both muscle strengthening and aerobic exercises. Limited research has compared these classes for college students. We examined changes in muscular strength, power, and endurance as well as body composition. Participants were 85 healthy college students enrolled in TWT (n = 36, age 22.6 ± 4.1 years, 72.2% male) or CF (n = 49, age 21.8 ± 3.2 years, 55.1% male) classes meeting twice/wk for 8 weeks between October 2017 and May 2018. Baseline and posttest measurements included a vertical jump, grip strength, a 2 min push-up test, a 1 min squat test, height, weight, and a bioelectrical impedance analysis. Although no significant group × time interactions were found, there was a significant main effect of time for push-ups and squats (both p &lt; 0.001). Participants enjoyed the classes and most planned to continue. Both classes improved muscular endurance although no significant differences were found between them. Activity classes provide college students with an option for increasing their weekly PA and help maintain body composition. Future research should examine the benefits from longer or more frequent classes