High-Intensity Functional Training Improves Cardiorespiratory Fitness and Neuromuscular Performance Without Inflammation or Muscle Damage

Abstract

High-intensity functional training improves cardiorespiratory fitness and neuromuscular performance without inflammation or muscle damage. J Strength Cond Res 36(3): 615-623, 2022-We examined the effects of high-intensity functional training (HIFT) on cardiorespiratory and neuromuscular performance, as well as on inflammatory and muscle damage markers. Thirteen physically active healthy volunteers (aged 28.3 6 3.8 years, 5 men and 8 women) underwent 8 weeks of a group HIFT program performed 3 times per week. Each session consisted of 4 rounds of a 9-exercise circuit (30-second exercise and 15-second recovery). During the first and last weeks of training, venous blood was sampled daily to monitor changes in serum C-reactive protein (CRP) and creatine kinase (CK). After 8 weeks of HIFT, body fat decreased by 0.64 6 1.01 kg (p 5 0.041), maximal oxygen uptake improved by 1.9 6 2.2 ml•kg 21 •min 21 (p 5 0.009), countermovement jump by 2.6 6 1.5 cm (p 5 0.001), bench press 1-repetition maximum (1RM) by 4.5 6 3.8 kg (p 5 0.001), maximum number of bench press repetitions at 65% 1RM by 4 6 5 repetitions (p 5 0.03), and abdominal muscle endurance by 6 6 4 repetitions (p , 0.001). In both week 1 and week 8 of training, CK increased mildly in the morning after the first session of the week (main effect for day, p 5 0.008), whereas no significant changes were observed in CRP (p 5 0.31). During week 8, CK on all days was ;32% lower compared with week 1 (160 vs. 235 U•L 21 ; main effect of week 1 vs. week 8, p 5 0.027), whereas CRP remained unchanged (p 5 0.225). This HIFT program was effective in improving cardiorespiratory and neuromuscular physical fitness without causing significant inflammation or muscle damage in physically active subjects.

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

“…Both groups demonstrated statistically significant enhancements in LBM at the end of the HIFT training by +1.11 ± 0.65 (2.1 percent) and 1.25 ± 1.59 (2.2 percent) for the LL and ML groups respectively, both significantly different compared with the CON group. These findings are consistent with previous reports examining HIFT on similar-level trained individuals, such as recreationally active individuals by ~3.3% [ 37 ] or trained individuals by ~2.0% [ 19 ]. In contrast, Feito et al [ 17 ] demonstrated significant reductions in % of fat mass, but not in bone-free lean mass, after 16 weeks of CrossFit training, in relatively experienced individuals.…”

“…Even though it was expected that both groups would show improvements, it was hypothesized that the ML group would have greater improvements compared with the LL group in LBM and maximal strength. To our knowledge, only a few studies have previously examined the effect of HIFT training on body composition and maximal strength performance for a relatively long period of training (8–16 Weeks) [ 16 , 19 , 20 , 21 , 36 , 37 ]. In the present study we demonstrated that three HIFT sessions per week for 12 weeks (a total of 36 sessions), led to improvements in performance and overall body composition by reducing body fat mass and increasing LBM.…”

Effect of a 12-week training program on the anthropometric and physiological profiles of some participants registered in a fitness center in Douala, Cameroon

“…This time-dependent data on the improvement of biological parameters can evolve especially when taking into consideration nature, duration, and intensity. Several studies have reported the benefits of regular physical and sports activities for times of 12 weeks or less (Brisebois et al, 2018;Murawska-Cialowicz et al, 2015;Park et al, 2019;Posnakidis et al, 2020;Sun et al, 2019). These studies, which are mostly Caucasian, use a high-intensity functional training (HIFT) program.…”

High-Intensity Functional Training for Firefighters

“…Posnakidis et al (68) examined the effects of HIFT on cardiorespiratory and neuromuscular performance, as well as on inflammatory and muscle damage markers. Their participants underwent 8 weeks of a group HIFT, and the sessions consisted of 4 rounds of a functional exercise circuit including 9 exercises with a W:R of 30:15.…”

“…In an observational study involving Dutch firefighters, Bos et al (13) showed that skill-based tasks are performed over a wide range of durations, which suggests that work-to-rest ratios and exercise intensity need to be systematically varied when performing HIFT protocol for prolonged periods. However, individuals without any previous training experience are recommended to follow a work-to-rest ratio of 30 s:15 s or 20 s:10 s for 4–8 weeks (12,68). Training with these parameters will increase anaerobic capacity (12,38,84), while also inducing functional adaptations, which prepares participants for subsequent higher intensity efforts.…”