High-intensity functional training (HIFT) is an exercise modality that emphasizes functional, multi-joint movements that can be modified to any fitness level and elicit greater muscle recruitment than more traditional exercise. As a relatively new training modality, HIFT is often compared to high-intensity interval training (HIIT), yet the two are distinct. HIIT exercise is characterized by relatively short bursts of repeated vigorous activity, interspersed by periods of rest or low-intensity exercise for recovery, while HIFT utilizes constantly varied functional exercises and various activity durations that may or may not incorporate rest. Over the last decade, studies evaluating the effectiveness of HIIT programs have documented improvements in metabolic and cardiorespiratory adaptations; however, less is known about the effects of HIFT. The purpose of this manuscript is to provide a working definition of HIFT and review the available literature regarding its use to improve metabolic and cardiorespiratory adaptations in strength and conditioning programs among various populations. Additionally, we aim to create a definition that is used in future publications to evaluate more effectively the future impact of this type of training on health and fitness outcomes.

Background: Although regular exercise is recommended for preventing and treating overweight/obesity, the most effective exercise type for improving cardiometabolic health in individuals with overweight/obesity remains largely undecided. This network meta-analysis aimed to evaluate and rank the comparative efficacy of 5 exercise modalities on cardiometabolic health measures in individuals with overweight/obesity.Methods: A database search was conducted in MEDLINE, Embase, Scopus, and Web of Science from inception up to September 2020. The review focused on randomized controlled trials involving exercise interventions consisting of continuous endurance training, interval training, resistance training, combined aerobic and resistance training (combined training), and hybrid-type training. Exercise interventions aimed to improve somatometric variables, body composition, lipid metabolism, glucose control, blood pressure, cardiorespiratory fitness, and muscular strength. The Cochrane risk of bias tool was used to evaluate eligible studies. A random-effects network meta-analysis was performed within a frequentist framework. The intervention ranking was carried out using a Bayesian model where mean and SD were equal to the respective frequentist estimates.Results: A total of 4331 participants (59% female; mean age: 38.7±12.3 years) from 81 studies were included. Combined training was the most effective modality and hybrid-type training the second most effective in improving cardiometabolic health-related outcomes in these populations suggesting a higher efficacy for multicomponent exercise interventions compared to single-component modalities, that is, continuous endurance training, interval training, and resistance training. A subgroup analysis revealed that the effects from different exercise types were mediated by gender.Conclusions: These findings corroborate the latest guidelines on exercise for individuals with overweight/obesity highlighting the importance of a multicomponent exercise approach to improve cardiometabolic health. Physicians and healthcare professionals should consider prescribing multicomponent exercise interventions to adults with overweight/obesity to maximize clinical outcomes.Registration: URL:https://www.crd.york.ac.uk/PROSPERO/; Unique identifier: CRD42020202647

Numerous studies have established the usefulness of pedometers and accelerometers as objective activity monitors. Under laboratory conditions, some of these devices have been shown to provide accurate and reliable measures of steps. However, limited data exist on the performance of these devices under free-living conditions. This study aimed 1) to compare the effects of speed and body mass index (BMI) on the step count accuracy of five different accelerometer-based activity monitors and a pedometer during treadmill walking, 2) to compare the performance of these devices in a free-living environment, and 3) to compare the step counts of three generations of a single device (ActiGraph) against a criterion method. Fifty-six individuals wore six activity monitors while performing treadmill walking (40, 54, 67, 80, and 94 m·min⁻¹) and during 1 d of free-living activity. The criterion measure of steps during treadmill walking was investigator-determined steps, whereas the criterion measure of steps during the free-living condition was the StepWatch. BMI had no effect on step count accuracy during treadmill walking. The StepWatch, activPAL™, and the AG7164 were the most accurate across all speeds, whereas the remaining devices were only accurate at 67 m·min⁻¹ and faster. In the free-living environment, the AG7164 recorded 99.5% ± 27% (mean ± SD) of StepWatch-determined steps. We demonstrated that BMI does not affect the step output of commonly used activity monitors during walking. In addition, 67 m·min⁻¹ seems to be the minimum speed required for accurate step counting, at least for most waist-mounted activity monitors. Finally, the StepWatch, AG7164, and activPAL™ were the most accurate devices on the TM, but only the AG7164 yielded comparable step counts to the StepWatch in the free-living environment.

Background: High-intensity functional training (HIFT) is a new training modality that merges high-intensity exercise with functional (multijoint) movements. Even though others exist, CrossFit training has emerged as the most common form of HIFT. Recently, several reports have linked CrossFit training to severe injuries and/or life-threatening conditions, such as rhabdomyolysis. Empirical evidence regarding the safety of this training modality is currently limited. Purpose: To examine the incidence of injuries related to CrossFit participation and to estimate the rate of injuries in a large cross-sectional convenience sample of CrossFit participants from around the world. Study Design: Descriptive epidemiology study. Methods: A total of 3049 participants who reported engaging in CrossFit training between 2013 and 2017 were surveyed. Results: A portion (30.5%) of the participants surveyed reported experiencing an injury over the previous 12 months because of their participation in CrossFit training. Injuries to the shoulders (39%), back (36%), knees (15%), elbows (12%), and wrists (11%) were most common for both male and female participants. The greatest number of injuries occurred among those who participated in CrossFit training 3 to 5 days per week (χ² = 12.51; P = .0019). Overall, and based on the assumed maximum number of workout hours per week, the injury rate was 0.27 per 1000 hours (females: 0.28; males: 0.26), whereas the assumed minimum number of workout hours per week resulted in an injury rate of 0.74 per 1000 hours (females: 0.78; males: 0.70). Conclusion: Our findings suggest that CrossFit training is relatively safe compared with more traditional training modalities. However, it seems that those within their first year of training as well as those who engage in this training modality less than 3 days per week and/or participate in less than 3 workouts per week are at a greater risk for injuries.

The ActiGraph (AG) is the most commonly used research-grade physical activity monitor. Although several investigators have examined the effects of the "low-frequency extension" (LFE) on step counts in the free-living environment, a direct comparison with a valid criterion method is lacking. We sought to determine the accuracy of the AG's LFE to measure step counts during laboratory and free-living activities in two versions of the device (GT1M and GT3X). Twenty-four participants wore the StepWatch 3 and two versions of the AG, with the LFE turned on (GT1M-LFE and GT3X-LFE) and the LFE turned off (GT1M-N and GT3X-N), on different days. Direct observation of steps and the ankle-worn StepWatch 3 served as the criterion methods for the treadmill and free-living condition, respectively. All statistical analyses were performed on the percent difference between the devices as [(measured - actual)/actual]. During treadmill walking, the GT1M-N and GT3X-N underestimated steps by approximately 60% at 40 m·min (P < 0.001) and by 31% at 54 m·min (P < 0.001). With the LFE turned on, this underestimation was reduced to 7% and 4% for the GT1M and GT3X, respectively. Under free-living conditions, both the GT1M-LFE and GT3X-LFE overestimated steps by approximately 32% (P < 0.001) whereas the GT1M-N and GT3X-N steps were underestimated by 30% and 25%, respectively (P < 0.001). Turning the LFE on lessens the underestimation of steps recorded at walking speeds ≤54 m·min for both the GT3X and GT1M. However, the increased sensitivity provided by the AG's LFE results in overestimation of steps taken throughout the day, when compared with the criterion device. Meanwhile, failure to turn the LFE on results in an underestimation of steps taken throughout the day.

High Intensity Functional Training (HIFT) is a training modality, characterized by multimodal exercises performed at high-intensity. Little is known about the training adaptations that occur as a prolonged training program. The purpose of this study was to examine changes in body composition, bone metabolism, strength, and skill-specific performance over 16-weeks of HIFT. Twenty-six recreationally active adult males (n = 9; 34.2 ± 9.1 y; 91.5 ± 17.7 kg; 178.5 ± 5.4 cm) and females (n = 17 = 36.4 ± 7.9 y; 91.5 ± 17.7 kg; 162.9 ± 7.0 cm) completed pre and post training assessments of body composition (Dual-Energy X-Ray Absorptiometry) and performance measures. Performance was assessed using three HIFT workouts (WOD 1–3) to assess strength, skill, and metabolic performance. Aside from the body composition measurements, all assessments were carried out at the local training facility. Training included participation in HIFT a minimum of twice a week for 16-weeks. Repeated measures analysis of variance revealed a significant gender x time interaction in Bone Mineral Content (BMC) (p = 0.027), where improvements favored women (1.0% ± 1.1%, p = 0.004) over men (-0.1% + 0.8%, p = 0.625). Further, region-specific analysis indicated that women (2.5% ± 3.0%, p < 0.005) experienced greater improvements in the trunk compared to men (-0.3% ± 1.8%, p = 0.621), while changes in leg BMC were comparable between women (0.8% ± 1.0%, p < 0.001) and men (0.3% ± 0.6%, p < 0.001). Although no other interactions were observed, significant performance improvements were noted for all participants in WOD 1 (18.3% ± 16.8%), absolute 5RM (14.4% ± 9.7%), relative 5RM (15.4% ± 9.2%), WOD 2 (5.7% ± 6.5%), and WOD 3 (–17.3% ± 14.7%). These data indicate that 16-weeks of HIFT resulted in positive outcomes in strength, metabolic conditioning performance, and body composition.