Changes in Body Composition and Strength after 12 Weeks of High-Intensity Functional Training with Two Different Loads in Physically Active Men and Women: A Randomized Controlled Study

The dose-dependent effect of caffeine supplementation on performance, reaction time and postural stability in CrossFit - a randomized placebo-controlled crossover trial

BACKGROUND

Caffeine (CAF) ingestion improves performance in a broad range of exercise tasks. Nevertheless, the CAF-induced, dose-dependent effect on discipline-specific performance and cognitive functions in CrossFit/High-Intensity Functional Training (HIFT) has not been sufficiently investigated. The aim of this study was to evaluate the effect of acute supplementation of three different doses of CAF and placebo (PLA) on specific performance, reaction time (RTime), postural stability (PStab), heart rate (HR) and perceived exertion (RPE).

METHODS

In a randomized double-blind placebo-controlled crossover design, acute pre-exercise supplementation with CAF (3, 6, or 9 mg/kg body mass (BM)) and PLA in 26 moderately trained CrossFit practitioners was examined. The study protocol involved five separate testing sessions using the Fight Gone Bad test (FGB) as the exercise performance evaluation and biochemical analyses, HR and RPE monitoring, as well as the assessment of RTime and PStab, with regard to CYP1A2 (rs762551) and ADORA2A (rs5751876) single nucleotide polymorphism (SNP).

RESULTS

Supplementation of 6 mgCAF/kgBM induced clinically noticeable improvements in FGBTotal results, RTime and pre-exercise motor time. Nevertheless, there were no significant differences between any CAF doses and PLA in FGBTotal, HRmax, HRmean, RPE, pre/post-exercise RTime, PStab variables or pyruvate concentrations. Lactate concentration was higher (p < 0.05) before and after exercise in all CAF doses than in PLA. There was no effect of CYP1A2 or ADORA2A SNPs on performance.

CONCLUSIONS

The dose-dependent effect of CAF supplementation appears to be limited to statistically nonsignificant but clinically considered changes on specific performance, RTime, PStab, RPE or HR. However, regarding practical CAF-induced performance implications in CrossFit/HIFT, 6 mgCAF/kgBM may be supposed as the most rational supplementation strategy.

Feasibility of Mobile Health App-Based Home Aerobic Exercise for Physical Performance in Healthy Young Adults

OBJECTIVE

To investigate the feasibility and effects of a mobile app-based home cycling exercise program compared to home cycling exercise without additional monitoring system. Compared with fitness facilities or outdoor exercise, home-based exercise programs effectively improve physical performance in an indwelling community. However, a flexible, informal environment may decrease motivation and impair adherence to physical exercise. Mobile devices for aerobic exercise and mobile applications provide real-time monitoring, immediate feedback, and encouragement to increase motivation and promote physical performance. We investigated the feasibility and effects of a mobile app-based home exercise program on body composition, muscular strength, and cardiopulmonary function.

METHODS

Between February and May 2023, 20 participants were randomly allocated to the intervention (mobile application with a tablet) and control groups, and they performed aerobic exercise using a stationary bicycle for ≥150 minutes per week for 6 weeks (≤30-minute exercise session, with 3-minute warm-up and 3-minute cool-down). Karvonen formula-based heartrate defined the weekly increase in exercise intensity. Outcome measures included body-composition parameters, isokinetic knee flexor and extensor strength tests, cardiopulmonary exercise test results, and rate of target heart rate (HR) achievement. Participants were assessed at baseline and after the intervention.

RESULTS

Unrelated personal events led two participants to drop out. The intervention and control groups had similar baseline characteristics. Compared with the control group, in the post-intervention isokinetic strength test, bilateral knee flexor and extensor power, and time to target HR achievement significantly increased each week in the intervention group.

CONCLUSION

Home-based exercise to achieve long-term cardiovascular fitness with portable electronic/mobile devices facilitates individualized exercise using real-time feedback to improve motivation and adherence.

The Acute and Chronic Effects of Resistance and Aerobic Exercise in Hemostatic Balance: A Brief Review

Hemostatic balance refers to the dynamic balance between blood clot formation (coagulation), blood clot dissolution (fibrinolysis), anticoagulation, and innate immunity. Although regular habitual exercise may lower the incidence of cardiovascular diseases (CVD) by improving an individual’s hemostatic profile at rest and during exertion, vigorous exercise may increase the risk of sudden cardiac death and venous thromboembolism (VTE). This literature review aims to investigate the hemostatic system’s acute and chronic adaptive responses to different types of exercise in healthy and patient populations. Compared to athletes, sedentary healthy individuals demonstrate similar post-exercise responses in platelet function and coagulatory and fibrinolytic potential. However, hemostatic adaptations of patients with chronic diseases in regular training is a promising field. Despite the increased risk of thrombotic events during an acute bout of vigorous exercise, regular exposure to high-intensity exercise might desensitize exercise-induced platelet aggregation, moderate coagulatory parameters, and up-regulate fibrinolytic potential via increasing tissue plasminogen activator (tPA) and decreasing plasminogen activator inhibitor (PAI-1) response. Future research might focus on combining different types of exercise, manipulating each training characteristic (frequency, intensity, time, and volume), or investigating the minimal exercise dosage required to maintain hemostatic balance, especially in patients with various health conditions.

Effects of a Six-Week International Tour on the Physical Performance and Body Composition of Young Chilean Tennis Players

In tennis, it is common for young male tennis players to spend several weeks away from their local training camps during the competition season, which could affect their performance. The purpose of the study was to analyze the effects of a six-week international tour on physical performance and body composition in young Chilean tennis players. Twenty-four men between the ages of 14 and 16 participated in this research. In body composition and anthropometric measurement, body weight, height, skinfolds, and perimeters were measured. Body fat percentage (BFP) and skeletal muscle mass (SMM) were calculated. For physical performance, 5-m and 10-m sprints, modified agility test (MAT test), countermovement jump (CMJ), and medicine ball throw (MBT) were evaluated. Results show that, in body composition, BFP and SMM significantly decreased post-tour (p < 0.05; effect sizes ranging from 0.23 to 0.33, respectively). In physical performance, agility and 5-m and 10-m sprints significantly decreased (p < 0.05, effect sizes ranging from −0.63 to 1.10). We conclude that after a six-week international tour, BFP, SMM, agility, and speed (linear sprint) tend to decrease significantly, with a greater effect in the sprint tests.

Effectiveness of either short-duration ischemic pre-conditioning, single-set high-resistance exercise, or their combination in potentiating bench press exercise performance

This study compared the effects of short-duration ischemic preconditioning, a single-set high-resistance exercise and their combination on subsequent bench press performance. Twelve men (age: 25.8 ± 6.0 years, bench press 1-RM: 1.21 ± 0.17 kg kg^-1 body mass) performed four 12 s sets as fast as possible, with 2 min of recovery between sets, against 60% 1-RM, after: a) 5 min ischemic preconditioning (IPC; at 100% of full arterial occlusion pressure), b) one set of three bench press repetitions at 90% 1-RM (PAPE), c) their combination (PAPE + IPC) or d) control (CTRL). Mean barbell velocity in ischemic preconditioning was higher than CTRL (by 6.6-9.0%, p < 0.05) from set 1 to set 3, and higher than PAPE in set 1 (by 4.4%, p < 0.05). Mean barbell velocity in PAPE was higher than CTRL from set 2 to set 4 (by 6.7-8.9%, p < 0.05), while mean barbell velocity in PAPE + IPC was higher than CTRL only in set 1 (+5.8 ± 10.0%). Peak barbell velocity in ischemic preconditioning and PAPE was higher than CTRL (by 7.8% and 8.5%, respectively; p < 0.05). Total number of repetitions was similarly increased in all experimental conditions compared with CTRL (by 7.0-7.9%, p < 0.05). Rating of perceived exertion was lower in ischemic preconditioning compared with CTRL (p < 0.001) and PAPE (p = 0.045), respectively. These results highlight the effectiveness of short-duration ischemic preconditioning in increasing bench press performance, and suggest that it may be readily used by strength and conditioning coaches during resistance training due to its brevity and lower perceived exertion.

The Addition of High-Load Resistance Exercises to a High-Intensity Functional Training Program Elicits Further Improvements in Body Composition and Strength: A Randomized Trial

The current study aimed to examine the effects of adding specific high-load resistance exercises to a high-intensity functional training (HIFT) program on healthy adults’ physical fitness and body composition. Twenty recreationally active volunteers (30 ± 4 y, 12 females, 8 males) were randomly assigned to either a HIFT-control (HIFT-C, n = 10) or HIFT-power (HIFT-P, n = 10) group and trained three times per week for eight weeks. The HIFT-C protocol included four rounds of an 8-exercise circuit (30:15 s work: rest, 2 min rest after the second round). The exercises used were clean-and-press, box jump, TRX chest press, wall ball throws, burpees, repeated 10 m sprints, sumo squat-and-upright row, and abdominal crunches. The HIFT-P-group replaced TRX chest press with bench press and squat-and-upright row with squat, both at an intensity of 80% 1 RM. Before and after the intervention, participants underwent an evaluation of body composition, cardiorespiratory fitness, vertical jump, 1 RM bench press, and the maximum number of abdominal crunches in 1 min. In both groups, cardiorespiratory fitness, squat jump, countermovement jump, bench press 1 RM, and percent body fat improved significantly after the intervention (p < 0.050), while a trend towards significant time x group interaction was found for bench press 1 RM (p = 0.076), indicating a superiority of HIFT-P over HIFT-C. Muscle mass significantly increased by 3.3% in the HIFT-P group, while abdominal muscle endurance improved by 16.2% in the HIFT-C group (p < 0.050). Short-term HIFT resulted in improvements in whole-body cardiorespiratory and neuromuscular fitness and reduction of body fat. The addition of high-load resistance exercises was well tolerated and resulted in increased muscle mass and upper body maximal strength. HIFT-P programs can be suitable for individuals seeking to enhance muscle mass and physical fitness in a short time.